Characterization of Humic Acids from Raised Bog Peat

2014

Abstract Humic substances form most of the organic component of soil, peat and natural waters, but their structure and properties are very much dependent on the source. The aim of this study was to characterize humic acids from raised bog peat to evaluate the homogeneity of humic acids isolated from the bog bodies and to study peat humification impact on the properties of humic acids. Peat humic acids (HA) have an intermediate position between the living organic matter and coal organic matter, with their structure formed in a process where the relatively labile moieties (carbohydrates, amino acids, etc.) are destroyed, and thermodynamically more stable aromatic and polycyclic structures eme…

Immobilisation of humic substances

2002

Attempts were made to immobilise humic substances (HS) by grafting them onto different carriers (styrene-divinylbenzene copolymers, cellulose and silica) as well as by their crosslinking with formaldehyde. Reaction with Merrifield resin was used for the immobilisation of HS, coupling by means of water-soluble carbodiimides to carriers containing amino-groups. Crosslinking of HS with formaldehyde (also in presence of other substances able to enter polycondensation reactions with formaldehyde) was shown to be an efficient method for their insolubilisation. Properties of the obtained immobilised HS were studied, including their potential use as sorbents for several metal ions and organic subst…

Impact of catchment properties on aquatic chemistry in the rivers of Latvia

2010

The relationships between land use characteristics and aquatic chemistry (nutrient concentrations, major inorganic ions and indicators of organic matter concentrations) were analyzed to determine factors controlling the runoff of dissolved substances, spatial variability of water chemical composition and possible impacts of pollution sources in Latvia. Groups of factors were found to determine the variability of nutrient, organic matter and major inorganic ions concentrations. Bedrock geology and weathering of soil minerals affect the concentrations of inorganic ions, but the nature of the relationships between nutrient concentrations and those of land use are good indicators of human impac…

The role of higher education institutions in sustainability initiatives at the local level

2019

FNEGE 2, HCERES B, ABS 2; International audience; Universities are central players and important economic actors in many regions, and many of them are, in general, nationally and internationally active in respect of matters related to sustainable development. But there is a paucity of research which examines their contributions towards sustainability efforts at the local level, i.e. in the places they are situated. This paper addresses this need, by reporting on a qualitative study deploying a Matrix, which allows an analysis and reporting of regional sustainable development initiatives of a set of 22 universities in industrialised and developing countries. Recommendations to enhance their …

Flood pattern changes in the rivers of the Baltic countries

2015

Estimation of both the frequency and variation of spring floods is a key issue for the assessment and management of flood risks. Changes in river floods in Estonia, Latvia and Lithuania have been investigated in few national studies. However, there are no studies of the changes of flood patterns by using a common methodology for the rivers of this region. In this study flood pattern changes in the rivers of the Baltic countries were estimated applying trend and frequency analysis for the periods of 1922–2010, 1922–1960, 1961–2010 and 1991–2010, i.e. for the whole spring flood data sets, periods before and after 1960 (this year was considered as the beginning of the remarkable climate change…

The role of governance in realising the transition towards sustainable societies

2016

It is widely known that governance is central to the successful implementation of sustainable development policies and measures. Yet, there is a paucity of research which explore the links between governance and sustainability. This paper attempts to address this research need by providing an analysis of the role of governance in enabling - and to some extent - fostering a transition towards sustainable societies. A set of indicators for assessing the capacity for and willingness and commitment to transition to a more sustainable society is presented, enabling identification of direction of change. This paper presents the results of a study, in the context of which sustainability governance…

Biochar from Waste Derived Fuels as Low-Cost Adsorbent for Waste Hydrocarbons

2020

Abstract The aim of this study is to prove technical feasibility of combined refuse derived fuel (RDF) torrefaction and oily wastewater treatment approach by using RDF derived biochar as a sorption media. Biochars prepared from refuse derived fuels in torrefaction, carbonization and pyrolysis modes were analysed as fuels and as hydrocarbon sorbents. Changes of elemental composition and properties of material during thermal treatment and subsequent washing process have been analysed. Experimental evaluation of sorption behaviour of toluene and diesel fuel on obtained biochar performed. Our results show that torrefaction/carbonization of RDF coupled with the subsequent washing of biochar is a…

Biomass Waste Processing into Artificial Humic Substances

2021

Abstract To address the biomass waste processing problem and transform it into refractory forms of carbon, recently suggested hydrothermal carbonization (HTC) of biomass in alkaline environment can be considered as a prospective and climate neutral approach. Biomass HTC provides possibilities to obtain form of biochar (hydrochar) and artificial humic substances, however the conditions of the HTC have not been much studied. Optimization by Response Surface Methodology of the HTC using microwave treatment with three experimental variables (treatment temperature, length of microwave treatment, amount of biomass per volume) provides the possibility to significantly increase the yield of humic s…

Reconstruction of the Holocene palaeoenvironmental conditions accordingly to the multiproxy sedimentary records from Lake Pilvelis, Latvia

2015

Abstract Reconstruction of the Holocene palaeoenvironment conditions in Southeastern Latvia is based on multiproxy records from Lake Pilvelis: pollen, plant macrofossil and microfossil analysis; loss-on-ignition (LOI) measurements; 14 C dating; humic substances content; humification index; and elemental composition of gyttja organic mass. The data complex obtained in the result of multiproxy studies of sediments in Lake Pilvelis indicates significant changes in the depositional environment during the lake development. Data from Lake Pilvelis show that the start of organic-rich sediments formation before approximately 9750 cal BP, when birch–pine forest dominated in the surrounding landscape…

Decadal oscillations of the aquatic chemistry of river waters in Latvia

2018

Abstract. Water quality changes of surface waters can be used to assess human impact intensity, but of importance is to consider also impacts of climate change/variability and naturally occurring changes of environmental quality. In Latvia, during the recent decades a major reduction of anthropogenic pressure has happened due to restructuring of economy and industrial production, resulting in major decrease of loading of many groups of pollutants. However, trends and driving factors for other groups of substances have not been much studied. Long term (1980–2012) results of hydrochemical monitoring, performed in rivers of Latvia, are analysed during this study in connection with long-term se…

Arsenic Sorption onto Peat and Iron Humates

2012

Environmental pollution with arsenic is a global problem; therefore, new remediation methods are needed. Peat modified with iron compounds and iron humates were prepared and tested for sorption of arsenic compounds. The highest sorption capacity was observed when iron-modified peat was used. Sorption of different arsenic speciation forms onto iron-modified peat sorbents was investigated as a function of pH, reaction time and temperature. Sorption capacity increases with temperature and was spontaneous and endothermic.

Assessment of the changes of COD and color in rivers of Latvia during the last twenty years

1998

Analysis of long-term records of the concentrations of water color and chemical oxygen demand for nine river sites in Latvia is reported. The period of observations lasted for the last 20 years. Characteristic features of data include non-normal distributions, serial correlation, seasonality and presence of mostly significant downward trends. In Latvia, the main water quality changes could be explained by the changes of anthropogenic impact and the type of catchment management over the last 20 years.

Highlighting inconsistencies regarding metal biosorption.

2015

Thousands of articles have been devoted to examine different types of biosorbents and their use in cleaning polluted waters. An important objective of some studies has been the identification of the biosorption mechanisms. This type of investigation is not always performed, as it can only be done if scientists are aware of all mechanisms that, at least theoretically, control the removal of the target substances. Mistakes are often made, even in highly cited review articles, where biosorption mechanisms are named and/or grouped. The aim of this article is to highlight errors and inaccuracies as well as to discuss different classification systems of the biosorption mechanisms. This article se…

Valorisation of Berry Pomace: From Waste to Bioactive Compounds

2018

Fruits and berries are amongst the essential food components and their processing is a major direction of food industry.

Normative Principles for Adaptation to Climate Change Policy Design and Governance

2012

Recognising climate change as a highly complicated and basically unstructured problem, the purpose of this paper is to suggest a theoretical frame supplemented with practical elements for adaptation to climate change policy design in the context of the requirements of sustainable development normative principles and criteria. The paper attempts to break the business-as-usual approach to policy design and decision-making practice concerning complicated and unstructured problems. The first recommendation for achieving that purpose is the application of a systemic and analytical approach to the elaboration process of adaptation policy, required by the United Nations’ Framework Convention on Cl…

Immobilized humic substances as sorbents

2005

A new method was developed for the immobilization of humic substances. Humic acids (HA) immobilized onto different carriers were studied as sorbents for organic and inorganic substances. The sorption isotherms of 4-aminoazobenzene, Crystal Violet, Methylene Green, and flavine mononucleotide on immobilized HA show that pH and salt concentration have a significant effect on the sorption process, largely depending on the properties of polymeric matrix. Humic acids from different sources showed differing sorption capacity for the studied groups of substances.

Effects of malvidin, cyanidin and delphinidin on human adipose mesenchymal stem cell differentiation into adipocytes, chondrocytes and osteocytes.

2019

Abstract Background Anthocyanidins are plant phytochemicals found at high concentrations in berries, vegetables and flowers. Anthocyanidins have been extensively investigated due to their antioxidative, antidiabetic and anti-inflammatory effects. Few studies show that anthocyanidins decrease obesity and improve bone density. However, the effects of anthocyanidins on tissue regeneration have not been sufficiently clarified. Human mesenchymal stem cells (MSCs) are multipotent adult stem cells responsible for the regeneration of fat, bone and cartilage. Although MSCs are often used for screening of biologically active compounds, so far, the effect of anthocyanidins on MSC differentiation has n…

Refuse Derived Fuel Gasification Possibilities in Small Scale Units

2018

Fossil fuels use reduction and waste recycling are two great challenges facing our society nowadays. A concept intended to solve both problems is Waste-to-Energy (WtE) approach (Brunner and Rechberger in Waste Manag 37: 3–12, 2015). The routes to the energy recovery can be grouped as thermo-chemical and biochemical approaches and the selection of the WtE technologies also depends on the waste composition. Waste sources can be industrial and agricultural production and urban regions but growing attention is paid to municipal solid waste in OECD countries (Hoornweg and Bhada-Tata in What a waste: a global review of solid waste management. World Bank, Washington, DC 2012) consisting dominantly…

On the way to ‘zero waste’ management: Recovery potential of elements, including rare earth elements, from fine fraction of waste

2018

Abstract Existing schemes of solid waste handling have been improved implementing advanced systems for recovery and reuse of various materials. Nowadays, the ‘zero waste’ concept is becoming more topical through the reduction of disposed waste. Recovery of metals, nutrients and other materials that can be returned to the material cycles still remain as a challenge for future. Landfill mining (LFM) is one of the approaches that can deal with former dumpsites, and derived materials may become important for circular economy within the concept ‘beyond the zero waste’. Perspectives of material recovery can include recycling of critical industrial metals, including rare earth elements (REEs). The…

Optimization of microbial biopreparations for soil quality improvement: Testing new formulations

2015

Data on physical and chemical characterization of wood combustion products derived at cogeneration power plants

2021

The data presented in this article are related to the research paper “Granulation of fly ash and biochar with organic lake sediments – A way to sustainable utilization of waste from bioenergy production” [1] in the context of waste material investigation and possible valorization instead of disposal. This article provides a comprehensive chemical and physical characterization of wood combustion products – fly ashes, bottom ashes, mixed ashes and biochar. Multiple analytical techniques and methodology were exploited to investigate the composition of wood combustion products, among them a loss on ignition, potentiometry, colorimetry, X-ray diffractometry, X-ray fluorescence spectrometry, indu…

Development of national climate and adaptation policy in Latvia

2009

PurposeThe purpose of this paper is to analyse the development and character of climate policy in Latvia with a special emphasis on policy instruments.Design/methodology/approachIn order to implement policies and measures effectively and monitor progress in achieving its mitigation targets, Latvia uses a wide mix of policy instruments, including regulations (e.g. environmental impact assessment procedures, environmental permits and standards, restrictions and prohibitions), economic and fiscal instruments (the natural resources tax, the excise tax for energy resources, user's charges), and voluntary agreements, also raising public awareness.FindingsThe combination of the policy instruments …

Evaluation of plankton communities in small highly humic bog lakes in Latvia

1998

This paper reports the results of a study performed at the Teici State Reserve in Latvia The results indicated that algal communities in brown water lakes were formed by species that were tolerant to a low pH and high humic substance concentration. The composition of the species of phytoplankton and zooplankton was comparatively simple. A significant correlation was found between the number of species of phytoplankton, zooplankton, and the pH value. Similarly there was a clear relationship between the taxonomic composition of phytoplankton, zooplankton, and the trophic state of the lakes. Dyseutrophic lakes were characterized by comparatively higher biodiversity of planktonic communities th…

Sorption of V and VI group metalloids (As, Sb, Te) on modified peat sorbents

2016

AbstractThe present work investigates arsenic, antimony and tellurium sorption using iron modified peat. The results were obtained using batch tests and the sorption was studied as a function of initial metalloid concentration, pH and sorption time, as well as the presence of competing substances. The obtained results indicate that modification of peat with Fe compounds significantly enhances the sorption capacity of the sorbents used for sorption of arsenic, antimony and tellurium. The optimal pH interval for the sorption of Sb(III) is 6.5–9 and for As(V) and Sb(V) – 3–6, while As(III) and tellurium sorption using Fe-modified peat is favourable in a wider interval of 3–9. The presence of c…

Environmental Quality of Groundwater in Contaminated Areas—Challenges in Eastern Baltic Region

2020

The lack of water in the future will force society to find more sophisticated solutions for treatment and improvement of groundwater wherever it comes from. Contamination of soil and groundwater is a legacy of modern society, prevention of contaminants spread and secondary water reuse options shall be considered. The aim of the book chapter is to give oversight view on problems and challenges linked to groundwater quality in Eastern Baltic region whilst through case studies explaining the practical problems with groundwater monitoring, remediation and overall environmental quality analysis. The reader will get introduced with case studies in industry levels as credibility of scientific fund…

Decontamination of Seawater in a Harbor: Case Study of Potential Bioterrorism Attack

2021

Bioterrorism attack to large harbors is likely, simply by the discharge of intentionally infected ship’s ballast water. Therefore, the ships must be equipped with the control probes of extensive microbial growth in the ballast water tanks to avoid such a scenario. In case of intentional discharge of ballast water containing Bacillus anthracis, a two-dimensional disinfection of the harbor’s seawater surface can be made using hydrophobic or surface-active disinfectant, by using humic acid with trimethylammonium groups, concentrating in the monomolecular layer on water–air interphase. It will prevent the formation and dispersion of the deadly bioaerosol to atmosphere after a bioterrorism attac…

Behaviour of Nanomaterials in the Environment: A Study of Interaction between Humic Acids and Fullerene C60

2010

Interaction between buckminsterfullerene and humic substances of different origin was investigated using fluorescence spectrometry as function of concentration of humic substances, pH and ionic strength. Binding constants of humic substances and buckminsterfullerene were calculated. It can be suggested that the complexation was driven by hydrophobic interaction depending on properties of the interacting compounds. Hydrophobic interaction model was indicated by linear Stern–Volmer plot, and high Kd values characterized interaction between buckminsterfullerene and humic acids. The results of this study support the development of understanding of fate of nanomaterials in environment as well as…

Education for Sustainable Development: A University Perspective

2021

Universities have a number of functions in developing Education for Sustainable Development (ESD): conducting study/teaching process themselves, participation in the development of study materials for other fields of studies, involvement in the development of study methods, as well as a responsibility for Sustainable Development Science. An equally important role of universities in the ESD process is the “training of trainers”—preparation of new teachers, who are aware of the need to promote the sustainable development process, are equipped with a systemic understanding of processes in the society and natural world, and know the local culture and traditions. The Aichi-Nagoya Declaration on …

Catalytic activity of humic substances in condensation reactions

1998

Abstract Humic substances (HS) have considerable impact on the fate of organic xenobiotics in natural environments. This paper reports on the catalytic activity of HS in condensation reactions of carbonyl compounds with active methylene compounds, using Knoevenagel and Claisen-Schmidt reactions as examples. Of the HS, the aquatic fulvic acids are the most active, but the velocity of condensation reactions depends also on the temperature, concentration and form of HS (free or salt) used, and the solvent.

Analysis of composition, morphology, and biosynthesis of cuticular wax in wild type bilberry (Vaccinium myrtillus L.) and its glossy mutant

2021

Abstract In this study, cuticular wax load, its chemical composition, and biosynthesis, was studied during development of wild type (WT) bilberry fruit and its natural glossy type (GT) mutant. GT fruit cuticular wax load was comparable with WT fruits. In both, the proportion of triterpenoids decreased during fruit development concomitant with increasing proportions of total aliphatic compounds. In GT fruit, a higher proportion of triterpenoids in cuticular wax was accompanied by a lower proportion of fatty acids and ketones compared to WT fruit as well as lower density of crystalloid structures on berry surfaces. Our results suggest that the glossy phenotype could be caused by the absence o…

Composition, sun protective and antimicrobial activity of lipophilic bilberry (Vaccinium myrtillus L.) and lingonberry (Vaccinium vitis-idaea L.) ext…

2021

Abstract Berries of the genus Vaccinium found in bogs and forest of Northern Europe are a valuable source of biologically active substances containing sterols, unsaturated fatty acids, flavanoids, anthocyanins. The presence of these compounds provides various health benefits of berry use – treatment of urinary tract inflammation, controls levels of sugar in the blood, improves cardiovascular health and reduces negative effects of oxidative stress caused by free radicals. The studied bilberry (Vaccinium myrtillus L.) and lingonberry (Vaccinium vitis-idaea L.) lipids were fractionated using normal-phase chromatography and they were found to contain fatty acids (oleic, linoleic acid), sterols …

FeOOH and Mn8O10Cl3modified zeolites for As(V) removal in aqueous medium

2017

BACKGROUND Arsenic in drinking water poses serious potential health risks in more than 30 countries with total affected population of around 100 million people. The present study is devoted to the development of innovative sorbents based on zeolite materials for As(V) sorption by modifying raw materials with iron oxyhydroxide and manganese oxychloride. Natural clinoptilolite and synthetic zeolite A were modified in order to obtain improved sorption of As(V). Sorption properties of newly developed sorbents were studied. Zeolites containing natural clinoptilolite are chosen due to relatively low cost and their broad use in industrial production as well as characteristic large surface area. RE…

Antioxidative, hypoglycaemic and hepatoprotective properties of five Vaccinium spp. berry pomace extracts

2019

Field-portable X-ray fluorescence spectrometry as rapid measurement tool for landfill mining operations: comparison of field data vs. laboratory anal…

2015

Landfill mining applied in reclamation at the territories of old dump sites and landfills is a known approach tended to global economic and environmental benefits as recovery of metals and energy i...

Properties and structure of raised bog peat humic acids

2013

Abstract Humic substances form most of the organic components of soil, peat and natural waters, and their structure and properties differ very much depending on their source. The aims of this study are to characterize humic acids (HAs) from raised bog peat, to evaluate the homogeneity of peat HAs within peat profiles, and to study peat humification impact on properties of HAs. A major impact on the structure of peat HAs have lignin-free raised bog biota (dominantly represented by bryophytes of different origin). On diagenesis scale, peat HAs have an intermediate position between the living organic matter and coal organic matter, and their structure is formed in a process in which more labil…

THE EVALUATION OF STABLE ISOTOPIC RATIOS 13C AND 15N IN HUMIC ACIDS ALONG A FEN PEAT PROFILE

2019

Mires are known as consistent environmental archives, but humic acids are the fraction of peat that is most recalcitrant and refractory to organic matter degradation, thus data on environmental changes during mire development can be recorded into them. This work was focused on the studies of stable isotopic ratios delta carbon-13 and delta nitrogen-15, and their distribution in humic acids within fen peat layers of different depths and peat composition. The variations in delta carbon-13 reflect isotopic variations in peat-forming plants over time and can be considered as a function of photosynthetic pathway that is being used to fix carbon dioxide. At the same time, variations in delta nitr…

Immobilised Humic Substances as Low-Cost Sorbents for Emerging Contaminants

2021

Environmental pollution with contaminants of emerging concern (CECs) is a worldwide problem that is receiving increasing attention. Although these substances have been released in the aquatic environment for a long time, wastewater treatment plants are still incapable of removing emerging contaminants completely. Consequently, trace metals, metalloids and pharmaceuticals, as well as surfactant leftovers, are often found in environmental samples. Environmentally friendly and cost-effective sorbents such as humic substances can be used for purification if their sorption properties are increased by immobilization. To our knowledge, immobilized humic substances have not been widely studied as s…

Climate Change Education in the Curricula of Technical and Classical Universities

2010

Climate change education is becoming an integral part of the education in study programs at universities in Latvia offering environmental education study programs. In this article, a comparison of approaches of climate change education in classical (University of Latvia) and technical (Riga Technical University) are discussed. Requirements of the labour market are the key factors influencing study content and study methods. Therefore, consultations with major stakeholders and with academics involved in environmental education (e.g. the Council of Environmental Education and Science), may be some of the main tools to implement new concepts.

Reviewing the role of ecosystems services in the sustainability of the urban environment: A multi-country analysis

2020

The urban environment is characterised by many pressures caused by population growth, transport (and its related emissions), and the damage to green areas. Yet, there is a variety of ecosystem services available in urban areas, which may be deployed to ameliorate the current problems and foster their sustainability. This paper reviews the role of ecosystem services as tools for sustainability, based on an urban setting. It also describes a series of multi-country case studies, where an assessment of their functions using a set of benefits valuation approaches such as health benefits, economic benefits, social benefits and benefits to climate resilience, are provided, along with an appraisal…

Nexus of Electrospun Nanofibers and Additive Processing—Overview of Wearable Tactical Gears for CBRNE Defense

2021

Due to complex nature of twenty-first century battlefield, soldiers must perform multiple tasks to protect nations while maintaining their own safety. Advances in technological innovations are critical to support such functionalities to enhance safety and security. Using nexus of electrospinning and additive processing, we present how recent developments can be used to produce new generation of protective fabrics with integrative force protection, sensing/detection of chemical, biological, radiological, nuclear, and high yield explosives (CBRNE), and biomedical functionalities. Although electrospinning has been in use for some time, the special blends and configurations of nanofibers, as de…

The chemistry of Cr(VI) adsorption on to poly(p-phenylenediamine) adsorbent

2019

Abstract Water pollution due to industrial processes has necessitated and spurred robust research into the development of adsorbent materials for remediation. Polyphenylenediamines (PPD) have attracted significant attention because of their dual cationic and redox properties. They are able to reduce Cr(VI) to Cr(III) in solution. Interrogation of the chemical processes involved in the Cr(VI) adsorption on para-PPD was primarily by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectroscopy. It was confirmed that the underlying oxidation of the amino groups to imines during the reduction of Cr(VI) to Cr(III) was irreversible. This process occurred at both acidi…

Accumulation of metals and changes in composition of freshwater lake organic sediments during the Holocene

2020

Abstract The distribution of metals in the strata of sediments deposited in the freshwater environment formed during the Holocene in the territory of Latvia has been studied rather insufficiently. Considering the large volume of accumulated organic matter in sediments, studies on the content of metallic elements in sediments can help to determine the peculiarities of the metal accumulation process in limnic systems and the biogeochemical cycling of metals. Lake Pilvelis, which is located in the eastern part of Latvia (the northern part of Europe), was selected as the main study site. Lake Pilvelis is a small lake of a glacial origin, and >90% of its depression is filled with organic-rich se…

Surface Activity of Humic Substances Within Peat Profile

2012

Humic substances are able to reduce the surface tension of their solutions and thus can act as surface-active substances in natural environment and possibly also for industrial applications. The ability to influence the surface tension of humic substance solutions depends on their origin. The objective of this study is a comparison of the ability of humic substances from peat profile to influence the surface tension of their solutions and identification of the structural characteristics of peat humic acids, determining their surfactant properties. Humic acids isolated from peat demonstrated significant impact of the surface tension of their solutions – they act as weak surfactants. The surf…

Fen peat in environmentally friendly technologies

2018

Abstract Using peat as an energy source is currently incompatible with Environmental Policy Strategy of Latvia and 2030 Climate and Energy Package of European Union. The European Commission is looking at cost-efficient ways to make European economy more climate-friendly and less energy consuming. Although, fen peat alongside raised bog peat is categorized as fossil fuel, it is not traditionally used as fuel or growth substrate or for any other significant purposes in reasonable amounts. Large areas of fens are neglected where fen peat is slowly mineralizing and emitting greenhouse gases, such as carbon dioxide and methane, that are ones of the main triggers for the Climate Change. Thus, to …

Hydrophilic Ionic Liquids in the Synthesis of Hantzsch Ester

2011

Hydrophilic Ionic Liquids in the Synthesis of Hantzsch Ester Hantzsch ester synthesis was investigated using (2-hydroxyethyl)-ammonium carboxylates, polar and hydrophilic ionic liquids possessing low toxicity and high biodegradability. The reaction rates and yields of the products in ionic liquids were greater than those in common organic solvents. The relationship between the structure of the ionic liquid used and the structure of the heterocyclic compound was investigated.

Peat humic acid properties and factors influencing their variability in a temperate bog ecosystem

2013

Studies of the properties of soil organic matter are essential for understanding the humification reactions and soil diagenesis processes. The aim of this study is to analyse properties of peat and peat humic acids as well as factors influencing their variability. Humic acids isolated from an ombrotrophic bog peat profile were used as study objects. Relations among peat age, decomposition and humification degree, botanical composition, and properties of peat humic acids (elemental, functional composition, spectral characteristics) were studied. The variability of peat properties was found to be less significant than the differences in the properties of peat-forming living matter, which indi…

Characterisation of humic acids in fen peat

2020

Fens store significant amounts of organic matter and thus are of high importance from the perspective of the organic carbon biogeochemical cycle. Fen peat comprises moderately to highly decomposed higher plant remains with relatively high mineral matter content. Humic acids form the major part of fen peat organic matter; they are also the most refractory and recalcitrant natural substances to degradation, and thus they contain essential information regarding mire and peat development over large periods of time as well as the organic carbon biogeochemical cycle. Moreover, humic substances in fen peat are a prospective resource for applications in agriculture and other sectors. The aim of thi…

A novel peat-based biosorbent for the removal of phosphate from synthetic and real wastewater and possible utilization of spent sorbent in land appli…

2015

AbstractRemoval of potentially harmful phosphorus compounds from wastewater by adsorption onto biosorbents is a cost-effective alternative to the conventional treatment methods. Raw peat and peat modified with iron(III) hydroxy ions were used in this study to remove phosphate ions from synthetic solution and household wastewater. Interaction of iron(III) ions with carboxylic groups of peat occurred during peat modification, which was confirmed by the FTIR technique. The effect of the initial phosphate concentration, pH, contact time, temperature, and ionic strength was studied in batch experiments. It was found that the sorption capacity increased with the increasing temperature, i.e. the m…

Bentonite-ionic liquid composites for Congo red removal from aqueous solutions

2021

Abstract Clay-organic composites have attracted great interest due to their ability to remove various contaminants from wastewater. The surfactants are the most commonly used organic compounds for clay modification. However, cationic surfactants are toxic and can be environmentally hazardous. Ionic liquids are a new promising alternative to the cationic surfactants due to lesser toxicity and appropriate thermal stability. The research aim is to prepare an environmentally friendly new class of clay sorbents modified with ionic liquids for potential applications in wastewater treatment from the textile industry. Imidazolium-based ionic liquids with different lengths of alkyl chains were inter…

FeOOH-modified clay sorbents for arsenic removal from aqueous solutions

2019

The presence of arsenic (As) in natural and anthropogenic soils causes severe pollution of groundwater due to its harmful carcinogenic effects. The present work describes the research activities for searching of appropriate innovative sorbents based on clay material for As sorption using iron oxy-hydroxide modification. Natural and manufactured clay was chosen for comparison of modification efficiency in order to obtain best sorption results for As(V). The results of pilot testing were obtained and the sorption was studied as a function of initial arsenic concentration. Obtained results indicate that modification of clay with Fe compounds significantly improves the sorption capacity of a ne…

Impact of the process of isolating humic acids from peat on their propertiesA paper submitted to the Journal of Environmental Engineering and Science.

2009

Humic substances (HS) can be isolated in preparative quantities from low rank coal, peat, and soil. Traditionally, treatment with solutions of NaOH, KOH, or metal salts (K4P2O7) has been used for their isolation. The aim of this article is to study the effectiveness of different technologies in extracting HS from peat as well as the impact of the different extractive technologies on the properties of the isolated HS. Yields of HS depend very much on the extraction process (extractant, temperature, pretreatment procedures, solvent, mixing intensity); however, the properties of the substances obtained (molecular mass, number of functional groups, spectral characteristics) differ significantly…

Coping with the impacts of Urban Heat Islands A literature based study on understanding urban heat vulnerability and the need for resilience in citie…

2018

The urban heat island (UHI) is a phenomenon whereby temperature levels in urban areas are higher than in surrounding rural settings. Urban heat islands are a matter of increasing concern, since they can affect communities by exacerbating air pollution and greenhouse gas emissions (due to the greater use of air conditioning) and the occurrence of heat-related illness, and may lead to higher levels of mortality. This paper provides a description of the phenomena of (UHI) and an analysis of how cities are vulnerable to it. It highlights the need for resilience and the variety of means by which the UHI can be tackled. It describes a set of trends in two regions in Germany and Australia, which i…

Authentication of berries and berry-based food products.

2021

Abstract Berries represent one of the most important and high-valued group of modern-day health-beneficial “superfoods” whose dietary consumption has been recognized to be beneficial for human health for a long time. In addition to being delicious, berries are rich in nutrients, vitamins, and several bioactive compounds, including carotenoids, flavonoids, phenolic acids, and hydrolysable tannins. However, due to their high value, berries and berry-based products are often subject to fraudulent adulteration, commonly for economical gain, but also unintentionally due to misidentification of species. Deliberate adulteration often comprises the substitution of high-value berries with lower valu…

Food and Environment: Trace Element Content of Hen Eggs from Different Housing Types

2013

AbstractEleven trace elements (Ba, Cu, Fe, Mn, Ni, Pb, Rb, Se, Sr, V, Zn) were quantitatively determined in hen egg samples collected from different poultry housing types (large-scale poultry farms, organic farms and domestic farms) over the territory of Latvia. Samples were wet digested and quantitatively analysed by total reflection X-ray fluorescence spectrometry (TXRF). The accuracy of analytical method was verified with analysis of certified reference material NCS ZC73017 (GSB-10)-Apple. The most variable range of concentrations and the highest content of elements were determined for hen egg samples derived from organic farms, while egg samples from domestic farms and poultry farms mos…

Thermal decomposition study of major refuse derived fuel components

2018

Abstract Refuse Derived Fuel (RDF) composed on biomass, paper, textiles, wood, synthetic polymers and other combustible materials is an alternative energy resource to implement Waste-to-Energy strategy. The aim of this study is to investigate the thermal decomposition characteristics of materials forming RDF by thermogravimetric analysis. Thermogravimetric (TG) analysis of RDF components demonstrates major differences in processes behind the thermal decomposition processes of waste components. Biomass decomposition can be divided into two distinct stages for wood, cotton, cotton wool and other biomass samples whereas three distinct stages can be distinguished for cardboard and paper samples…

A route to simple nonionic surfactants

2016

AbstractA method for the synthesis of nonionic surfactants – N-alkyl-O-(2-hydroxyethyl) carbamates is proposed by acylation of fatty amines with ethylene carbonate without any solvent or catalyst. The surface tension of the prepared surfactants was measured, toxicity and biodegradability were determined for the surfactant with n-dodecyl as a hydrophobic group and N-monosubstituted amide and hydroxyl groups for their hydrophilic part.

Analysis of biosynthesis and composition of cuticular wax in wild type bilberry (Vaccinium myrtillus L.) and its glossy mutant

2020

AbstractCuticular wax plays an important role in fruits in protection against environmental stresses and desiccation. In this study, biosynthesis and chemical composition of cuticular wax in wild type (WT) bilberry fruit was studied during development and compared with its natural glossy type (GT) mutant. The cuticular wax load in GT fruit was comparable to WT fruit. In both fruits, triterpenoids were the dominant wax compounds with decreasing proportion during the fruit development accompanied with increasing proportion of aliphatic compounds. Gene expression studies supported the pattern of compound accumulation during fruit development. GenesCER26-like, FAR2, CER3-like, LTP, MIXTA, andBA…

Remediation of Soil Contamination with Heavy Metals by Using Zeolite and Humic Acid Additives

2012

- Soil remediation at contaminated sites very often needs customized approach, because of the different content of pollutants. Various technologies from simple soil excavation and transporting to hazardous waste landfills to different kinds of remediation by vitrification and the use of additives can be used for the treatment of soil. A series of remediation experiments using zeolites and humic acids were applied to soil contaminated with copper. Remediation can be performed with easily available additive materials of natural origin found near the place of application, in order to diminish the leaching of contaminants. Soils contaminated and spiked with copper were mixed with additives, and…

Characterization of interaction between tricyclic structures containing pharmaceuticals, their models and humic substances.

2011

Their persistence and wide consumption identify pharmaceuticals as “emerging pollutants”. The complexation of pharmaceuticals containing adamantine ring structures and their model substances with humic acids (HA) of different origins was compared using fluorescence spectroscopy as a function of pH, humic acid concentration, ionic strength, and molecular mass of HA. Binding constants between the studied pharmaceuticals and humic acids were calculated. A combination of dynamic and static quenching processes as indicated by nonlinear Stern-Volmer plots and high Kd values were positively correlated with the concentration of carboxyl groups in the studied humic acids. For basic functional group-…

Small Scale Gasification Application and Perspectives in Circular Economy

2018

Abstract Gasification is the process converting solid fuels as coal and organic plant matter, or biomass into combustible gas, called syngas. Gasification is a thermal conversion process using carbonaceous fuel, and it differs substantially from other thermal processes such as incineration or pyrolysis. The process can be used with virtually any carbonaceous fuel. It is an endothermic thermal conversion process, with partial oxidation being the dominant feature. Gasification converts various feedstock including waste to a syngas. Instead of producing only heat and electricity, synthesis gas produced by gasification may be transformed into commercial products with higher value as transport f…

Chemical speciation of metals from marine sediments : assessment of potential pollution risk while dredging, a case study in southern Sweden

2020

Abstract Contamination associated with metals is a critical concern related to their toxicity, persistence, and bio-accumulation. Trace elements are partitioned into several chemical forms, which some are more labile during fluctuations in the environment. Studying the distribution of metals between the different chemical fractions contributes to assess their bioavailability and to identify their potential risk of contamination to surrounding environments. This study concerns the speciation of metals (Pb, Cr, Ni, Zn and Fe) from sediments coming out from Malmfjarden bay, Sweden. The aim was to assess the potential risk of metal pollution during present and future dredging as well as while u…

Trace Element Concentration and Stable Isotope Ratio Analysis in Blueberries and Bilberries: A Tool for Quality and Authenticity Control

2021

Vaccinium genus berries—wild bilberries (Vaccinium myrtillus L.) and cultivated highbush blueberries (Vaccinium corymbosum L.)—are consumed worldwide, and their consumption has a trend of stable increase. Thus, considering their wide use in ethnomedicine, for juice and jam production, as functional food, as well as their use in preparations of extracts which have application potential in pharmaceutical and cosmetics industries, studies regarding the composition of these berries are of special importance. The aim of this study is to characterise the elemental and isotopic composition, as well as variation in element concentration in bilberries gathered from different sites in Northern Europe…

Microbiological Stability of Bio-Based Building Materials

2021

The aim of this paper was to study the microbiological stability of bio-based composite building materials, which are made using organic-rich lake sediments (further – sapropel) with lime and magnesium cement as binders and hemp shives as filler. The microbial stability properties of the obtained composite materials were investigated and compared to similar composites. Because of their high organic content, these materials are prone to biodegradation; therefore, they were coated with ALINA LIFE TM organoclay coating, which helps to extend the product life, reducing the rate of biodegradation compared to the biocides used in industry. The effect of the coating on the resistance to decay by t…

Sorption of thallium(I) ions by peat.

2013

The increasing industrial use of thallium has raised the need for removal of this highly toxic element from wastewater. Thallium is more toxic than cadmium, copper, zinc, lead and mercury and as it is easily accumulated in humans, animals and plants, it poses a threat to both the environment and human health. Peat has been used as an effective, relatively cheap and easily available sorbent to treat waters containing heavy metals. In this study, peat was characterized and used as sorbent for the removal of Tl(I) ions from aqueous solution. The effect of initial Tl(I) concentration, pH, contact time, temperature and ionic strength was studied in batch mode. The maximum sorption capacity of pe…

Sedimentary humic substances from lakes in Latvia

1997

Humic and fulvic acids, isolated from sediments of lakes in different trophic states (Latvia) were studied. The humic substances (HS) were characterized by their elemental and functional composition, their spectral properties, and molecular mass. The humus properties strongly depend on the origin of the sedimentary HS. Substantial similarity between sedimentary HS from oligotrophic and dystrophic water bodies was found, unless the biology of these lakes greatly differs. Humic molecules from sediments of oligotrophic and dystrophic lakes are smaller, more uniform, and contain lower amounts of carboxyl- and hydroxyl-groups than HS from meso- and eutrophic water bodies. On the other hand, sedi…

Natural organic matter export from boreal catchments (the Salaca River basin, Latvia) and its influencing factors

2012

A noteworthy increase in the organic matter concentration and export, as well as water colour, in the catchments of the Salaca River has been observed during the last decades. This study investigates factors behind this increase: the impact of climate, land use and human loading changes on the concentrations and export of the organic matter in the Salaca River/Lake Burtnieks catchments. Proportion of wetlands in the river basin, type of land use, and runoff regime can be considered as the main factors influencing the organic carbon loadings. Despite a steady overall tendency of increase, considerable oscillations of organic matter loadings influenced by the changes in the river discharge re…

Valorization of Wild Apple (Malus spp.) By-Products as a Source of Essential Fatty Acids, Tocopherols and Phytosterols with Antimicrobial Activity

2018

The amplified production of fruit as well as burgeoning demand for plant-made food products have resulted in a sharp increase of waste. Currently, millions of tons of by-products are either being discarded or utilized rather ineffectively. However, these by-products may be processed and further incorporated as functional ingredients in making high-value food products with many physiological and biochemical effects. The chemical analysis of pomace oils using gas chromatography-mass spectrometry (GC/MS) and reversed-phase-liquid chromatography coupled with fluorescence detector (RP-HPLC/FLD) systems led to the identification and quantification of 56 individual lipophilic compounds including u…

Sorption of Hydrocarbons on Peat, and Possibilities for Using Peat-Based Oil Sorbent for Treatment of Polluted Areas

2017

The growing use and transport of crude oil and oil products has led to an increasing amount of spillages of various scales. In the event of an oil spill, it is important to stop the spill from spreading and to clean up the polluted environment. One of the possible ways of treating the polluted areas is the use of oil sorbents. The sorbents used for collecting oil in case of oil spills are mostly synthetic, which limits the possibilities of their disposal. The aim of our study is to investigate the possible use of peat and its modification products for oil and other hydrocarbon sorption. Peat is a prospective material for oil sorption because it has such advantages as low cost, biodegradabil…

Metals and Organochlorine Compounds in Fish from Latvian Lakes

1998

Organochlorines and metals have high toxicity and worldwide distribution in the aquatic environment. They are known to accumulate in sediments. In mollusks and fishes, they are bioconcentrated, even when released in minute quantities into the environment. This is important, as these chemicals have an adverse impact on species diversity, and accumulate in humans when seafood is consumed (Jaffar et al. 1988; Ruiter 1995). The nature and extent of accumulation and impact of persistent xenobiotics in water bodies depend on their sources; i.e. whether they are from industry, agricultural activities, transboundary transport with air masses (Sharif et al. 1993), geochemically determined elevated c…

Thermogravimetric analysis as express tool for quality assessment of refuse derived fuels used for pyro-gasification

2019

The development of pyro-gasification technologies makes necessary the development of new express analytical methods that are able to deal with the variability of feedstock and problems arising from it. Thermogravimetric proximate analysis of refuse derived fuels is a very fast, cheap and simple method for the determination of proximate and fractional composition. Development of this analytical approach may result in a very cost-effective method to describe wholesome composition and characteristics of feedstock used for pyrolysis and gasification processes in real time. The aim of this study was the development of such analytical method. Refuse derived fuel samples produced in Latvia and Est…

MODIFICATION OF HUMIC SUBSTANCES FOR DEVELOPMENT OF MATERIALS FOR ENVIRONMENTAL TECHNOLOGIES

2019

Humic substances are high molecular weight refractory polycationites formed during decay of living organic matter and through biosynthesis of low molecular weight organic substances (metabolites or decay products of living organisms). Presence of many functional groups in the structure of humic substances determines their ability to interact with metal ions forming stable complexes and influencing metal ion speciation in the environment and mobility, behaviour and speciation forms in the environment. Presently humic substances are a product of industrial scale and quantities in amounts of hundreds of tons are produced. The aim of this study is to analyse derivatization possibilities of humi…

Berry press residues as a valuable source of polyphenolics: Extraction optimisation and analysis

2018

Abstract Vaccinium genus berries (bilberries, blueberries, lingonberries, cranberries) are gathered in the wild as well as cultivated on an industrial scale for use in the food industry. Extraction of juices from these berries produces press residues (pomace) as a waste product. Berry press residues are an excellent source of phenolic compounds and have a potential of use as a polyphenol-rich material. The aim of the present study was to optimise the method of extraction of polyphenols (anthocyanins specifically) from berry press residues of American cranberry using the response surface method and to validate the optimal polyphenol/anthocyanin extraction conditions also for other Vaccinium …

Different Type Clay Amendments for Lead Immobilization in Contaminated Soils

2014

Contamination with lead in soil is a crucial problem in industrial and military sites. Immobilization of lead by natural and modified clay as soil amendment can be an effective solution to this problem. Quaternary and Devonian clays were chosen for modification with NaCl, CaCl2, FeOOH and Ca10(PO4)6(OH)2 in different proportions of Ca/P equimolar ratio to test and compare immobilization efficiency of lead (II) on raw and modified clays by using a batch leaching test. The aim of the study is to compare different types of raw and modified clays as soil amendments by lead immobilization properties.

Compositional and morphological analyses of wax in northern wild berry species.

2019

Accepted manuscript version, licensed CC BY-NC-ND 4.0. Aerial surfaces of plants are covered by a waxy cuticle protecting plants from excessive water loss and UV light. In the present study, composition and morphology of cuticular waxes of northern wild berry species bilberry (Vaccinium myrtillus L.), lingonberry (V. vitis-idaea L.), bog bilberry (V. uliginosum L.) and crowberry (Empetrum nigrum L.) were investigated. Scanning electron microscopy (SEM) revealed differences in epicuticular wax morphology, and gas chromatography–mass spectrometry (GC–MS) analysis confirmed variation in chemical composition of cuticular waxes between the berry species. The dominant compounds in bilberry and li…

Climate change policies and agendas: facing implementation challenges and guiding responses

2020

Climate policies are essential to mitigate climate change and to develop successful adaptation processes. However, there is a paucity of international studies that analyse the status of climate change policies. This paper reports on research undertaken in a sample of 13 highly diverse countries, in regards to their geography, socioeconomic development, vulnerability elements, adaptation, and climate-risks. The results draw attention to the global spread and standardisation of climate change policies, namely through the adoption of comprehensive National Adaptation Plans/Strategies (NAPs/NASs) that include mitigation measures and evaluation mechanisms. Although NAPs tend to take into account…

Characterisation of humic substances by acid catalysed transesterification

2002

Abstract The chemical composition of low molecular weight moieties linked to the core structures of humic substances (HS) are of substantial importance for the understanding of the chemical structures and mode of interactions of HS with other substances in the environment. In this study a novel approach to characterise certain low molecular weight compounds bound to HS is suggested. The method includes transesterification (TE) of ester and amide bound structures, and esterification (E) of free carboxylic groups using acid catalysed methanolysis followed by gas chromatography (GC)–mass spectrometry (MS) and GC-FID analysis. Methanolysis of five HS of different origin, demonstrated the presen…

Complex-forming properties of peat humic acids from a raised bog profiles

2013

Abstract Humic substances (HS) belong to the most powerful complex-forming agents, significantly affecting major and trace element speciation in natural environment. Several authors have focused on humic–metal interactions, using differing methods and comparing humic substances on different sources. However, the intrinsic differences among the HS of different origin and the impact of humification degree on the complex formation between humic substances and metals have not received the necessary attention until now. The aim of this study is to determine the Cu(II) complexing capacity and stability constants of Cu(II) complexes of humic acids (HA) isolated from two well-characterized raised b…

Sorption of humic substances on aquifer material at artificial recharge of groundwater

2003

Experiments in batch equilibrium system were carried out to evaluate the importance of physical and chemical factors determining the sorption efficiency of humic substances (HS) on aquifer material, which has been used for artificial recharge of groundwater (ARG) in drinking water production. Results showed that an increase of the amount of clay in the aquifer material and a decrease of pH in water increased the sorption efficiency. The sorption of higher molecular weight, more hydrophobic and aromatic HS (Aldrich and forest soil humic acids) were greater than the sorption of acidic HS (river fulvic acids), either on the aquifer material or to its representative sorbing phases, clay and org…

The role of transformation in learning and education for sustainability

2018

Education research has acknowledged the value of transformation, which offers an opportunity for researching and rethinking how appropriate and successful educational practices may be. However, despite the role of transformation in higher education and particularly in sustainability learning, there is a paucity of studies which examine the extent to which transformation and learning on matters related to sustainable development may be integrated. Based on this perceived research need, the purpose of this article is to present how transformation in learning in education for sustainability requires the commitment of Faculty and the engament of students. To do this, a set of qualitative case s…

Long-term changes of river discharge regime in Latvia

2008

The study of changes in river discharge is important for regional climate variability characterization and for development of an efficient water resource management system. The hydrological regime of rivers and their long-term changes in Latvia were investigated. Four major types of river hydrological regimes, which depend on climatic and physicogeographic factors, were characterized. These factors are linked to the changes observed in river discharge. Periodic oscillations of discharge, and low- and high-water flow years are common for the major rivers in Latvia. A main frequency of river discharge regime changes of about 20 and 13 years was estimated for the studied rivers. A significant …

Spectrofluorimetric study of dissolved organic matter in River Salaca (Latvia) basin waters

2012

Dissolved organic matter (DOM) in surface waters influences mineral weathering, nutrient cycling, aggregation of particulate matter and photochemical reactions in waters and aquatic communities. In this study, the effectiveness of UV and fluorescence measurements in distinguishing the origin of DOM and processes within the river basin were analyzed using the River Salaca basin as an example. The basin of River Salaca is characterized by low anthropogenic pressure, however, the water color during the last few decades has increased (an effect known as brownification). As tools to study the composition of dissolved organic substances in waters of the River Salaca and its tributaries the use of…

Potential of Baltic Region Peat in High Added-value Products and Environmentally Friendly Applications - A Review

2021

The present review is dedicated to using of peat on the example of fen peat in high added-value products and applications. Mainly, but not limited, last decade literature was analysed from the perspective of innovation potential of peat applications in environmental technologies on examples of studies from the Baltic Sea region. Paper covers a wide range of applications of peat products started from agriculture to medicine and cosmetics. A separate chapter is devoted to the deep-processed peat product - humic substances (humate, humic and fulvic salts and acids). Generalised dependence of product extraction rate and its properties, depending on the process parameters are provided. Widely ar…

Formation and Changes of Humic Acid Properties during Peat Humification Process within Ombrotrophic Bogs

2012

Studies of the living organic matter humification process are essential for understanding the carbon biogeochemical cycle. The aim of this study is to analyze relations between the properties of peat, peat humic acids and peat humification degree. The analysis has been done on samples of humic substances extracted from peat profiles in two ombrotrophic bogs and relations between peat age, decomposition and humification degree, botanical composition and properties of peat humic acids (elemental, functional composition) were studied. The found variability of peat properties is less significant than differences in the properties of peat-forming living matter, thus revealing the dominant impact…

Cuticular Wax Composition of Wild and Cultivated Northern Berries

2020

The outer-most layer of plant surface, the cuticle, consists of epi- and intra-cuticular wax. It protects the plant from dehydration, extreme temperatures and UV radiation, as well as attacks from pests such as molds and bacteria. Berry cuticular waxes are studied to understand the metabolism character (factors affecting wax layer composition in different berry species) and increase the microbial resistance and shelf life of berries. The aim of this study was analysis of the surface wax composition of nine species of wild and cultivated berries from Northern Europe. Cuticular wax analysis were done using gas chromatography-mass spectrometry. A total of 59 different compounds were identified…

Well water quality in Latvia

1996

A total of 2500 water samples from drinking water shallow wells and boreholes in rural areas of Latvia were collected. The samples were analyzed for 20 parameters. Well waters in Latvia can be characterized by a high content of organic (humic) substances. Mean values for analyzed water parameters are: 0.17 mg/1 NH4, 0.016 mg/1 NO2, 2.90 mg/1 NO3, 0.028 mg/1 PO4, 25.53 mg/1 Cl, 0.12 mg/1 Fe, 7.4 pH, 784 μ/cm conductivity, 24 degrees in PtCo scale color, 7.5 mgequiv/1 total hardness. Comparison with water quality criteria adopted in the USA and European Communiy indicate that water quality is often unsatisfactory. For example, nitrate concentrations exceed standards in nearly 20% of the surve…

Major and trace element distribution in the peat from ombrotrophic bogs in Latvia.

2011

This study was undertaken to analyse major and trace elements and the nature of their accumulation in peat, with a particular emphasis on peat properties and the impact of local and regional pollution sources on the character of element accumulation in ombrotrophic bogs in Latvia. The element concentration values in peat from Latvia reflect the local processes that affect element concentrations in the peat mass, indicating accumulation of trace elements – apparently of anthropogenic origin (Pb, Cd, Co, Ni and others) – in the upper layers of the peat profiles. In addition, they indicate accumulation of several elements (for example, As, Cr and others) in deeper layers of bog, possibly due t…

A study of weathered coal spectroscopic properties

2017

Abstract Current coal industry causes significant environmental pollution and the most air pollution deaths in the world, making the development of new eco-friendly applications one of the top priorities. Coal contains up to 50 % humic substances (HS), the majority of which is humic acid (HA). HA is well known for its beneficial properties and thus compounds extracted from coal can be used to develop new applications. To address this issue, we assessed structural composition of coal HS by measuring their spectroscopic properties. As the result, obtained spectra can be used to identify information about the molecules and thus allowing describing the composition of HS. The purpose of this stu…

A study of major and trace element accumulation in humic acids

2015

It has been widely studied recent as well as historic accumulation of elements in peat profiles depending on intensity of anthropogenic pollution and thereby peat profiles serve as archives for research of environmental change. Peat ability to accumulate major and trace elements depends on the character of element supply, potency of metal ions to bind functionalities in the peat structure, pH reaction, oxygen presence, presence of complexing compounds, inorganic ions and many other factors. The aim of this study is to assign major and trace element distribution in humic acids (HA) for two well characterized ombrotrophic peat profiles of Eipurs and Dzelve Bog and analyse factors affecting el…

Granulation of fly ash and biochar with organic lake sediments – A way to sustainable utilization of waste from bioenergy production

2019

Abstract The main waste generated during the thermochemical processes of biomass burning used for bioenergy production in cogeneration plants are ash and biochar which can be used as fertilizers in forestry and agriculture. However, several difficulties are attributed to possibilities of practical exploitation of ash and biochar due to the transporting, handling and mode of application. Granulation of energy generation waste has been shown in some circumstances as a cost-effective and environmentally friendly method. Production of granules (pellets) from wood ash and biochar leads to improved recycling and logistics of waste as well as helps to control and avoid undesirable environmental ef…

Characterization of Interaction Between Humic Acids and Buckminsterfullerene Using Flourescene Spectroscopy

2017

The interaction between buckminsterfullerene C60 and humic acids (HA) of different origins was compared using fluorescence spectroscopy as a function of pH, humic acid concentration, ionic strength. Binding constants between fullerene and humic acids were calculated. It can be suggested that the complexation was driven by hydrophobic interactions depending on the properties of the interacting compounds. Hydrophobic interaction model as indicated by linear Stern-Volmer plots and high Kd values is characterizing the interaction between buckminsterfullerene C60 and humic acids The results of this study support the development of an understanding of the fate of nanomaterials in the environment …

Humic acid reduces gonadotropin activity and hormonal sensitivity of frog oocytes

2005

The specific stimulatory effect of sturgeon Acipenser güldenstädti Br. gonadotropic hormone (GTH) on frog Rana temporaria L. oocyte maturation in vitro was investigated in relation to humic acid (HA) concentrations from 12.5 to 50 mg/l. HA was observed to bind to both the follicular membrane of the oocytes and the GTH molecule, reducing the oocytes' hormone sensitivity and maturation ability. It was also shown that HA inactivated GTH, lowering its specific ability to stimulate oocyte maturation.

Remote Sensing Observations of Thunderstorm Features in Latvia

2017

AbstractThunderstorms are the most hazardous meteorological phenomena in Latvia in the summer season, and the assessment of their characteristics is essential for the development of an effective national climate and weather prediction service. However, the complex nature of convective processes sets specific limitations to their observation, analysis and forecasting. Therefore, the aim of this study is to analyse thunderstorm features associated with severe thunderstorms observed in weather radar and satellite data in Latvia over the period 2006–2015. The obtained results confirm the applicability of the selected thunderstorm features for thunderstorm nowcasting and analysis in Latvia. The …

A circular economy: an analysis of the businesses awareness level in the Baltic Sea Region countries

2018

Circular economy is a model of production and consumption, which involves sharing, leasing, reusing, repairing, refurbishing and recycling existing materials and products as long as possible. In this way, the life cycle of products is extended. Unlike the traditional linear economic model based on a ‘take-make-consume-throw away’ pattern, a circular economy is based on the notion that all wastes can be considered as valuable resources in an almost closed loop, where products and the materials they contain are highly valued. In practice, it implies reducing waste to a minimum. Examination of the current knowledge and performance on resource efficiency and circular economy of industrial enter…

Long-term changes of precipitation in Latvia

2010

This study investigated long-term variability and trends in Latvia's annual, seasonal, monthly and daily precipitation using data from 10 meteorological stations for the period 1925–2006 and from station Riga University for the period 1850–2006. The obtained results indicate that during the 20th century a significant increase in precipitation has occurred in the cold season while the warm period showed a decreasing tendency. The annual precipitation totals showed a slight decrease, at half of the studied stations, due to opposite tendencies in cold season and warm season. The long-term trend in the annual precipitation in Riga (from 1850) was positive with large interannual and interdecadal…

Local Knowledge and Resources as Driving Forces of Sustainable Bioeconomy

2018

A major driving force to promote the idea of sustainable bioeconomy could be local experiences, skills and knowledge in respect to the use of local and natural materials (at first, biomaterials). Sustainable bioeconomy is a concept under development, and as such it requires argumentation and demonstration of efficiency. The aim of this chapter is to study the local knowledge of the Baltic region in terms of the applicability of local biomaterials in production. In the context of bioeconomy, there is an evident need to identify the possibilities for the use of natural and local materials as well as the knowledge to manage these resources. Natural materials of the Baltic region, such as hemp,…

Use of peat-based sorbents for removal of arsenic compounds

2013

Abstract It is important to apply sorbent materials for purification of water from arsenic contamination due to serious arsenic pollution worldwide. We have developed new sorbents based on natural materials that provide a cheap and environmentally friendly alternative. For the first time, peat modified with iron compounds and iron humates were tested for sorption of arsenic compounds. The highest sorption capacity was found in peat modified with iron compounds. We have found that sorption of different arsenic speciation forms was strongly dependent on solution pH, reaction time and temperature. Calculations of the sorption process using thermodynamic parameters indicate the spontaneity of s…

Development of a new peat-based oil sorbent using peat pyrolysis

2013

The growing use and transport of crude oil and oil products has led to increasing numbers of oil spillages of various scales. Oil sorbents have been extensively used for remediation of the consequences of such accidents. The aim of this study is to investigate the possible use of peat and its thermal treatment products for oil sorption. Peat as an oil sorbent has poor buoyancy characteristics, relatively low oil sorption capacity and low hydrophobicity. However, thermal treatment (low-temperature pyrolysis and synthesis of peat-based activated coal) helps to significantly improve its sorptive characteristics. Peat is a potential material for oil sorption because it has such advantages as lo…

COMPOSITION OF REFUSE DERIVED FUELS IN LATVIA AND ESTONIA IN COMPARISION WITH WORLDWIDE AVERAGE VALUES

2019

Information about composition of RDF worldwide was collected using literature analysis. RDF samples produced in Latvia and Estonia were collected, those fractional and elemental composition analyzed using standard methods. Comparing obtained results with worldwide data we have found that the quality of local RDFs in general is higher than typical values, while elevated content of chlorine must be mentioned as a problem. Results also show that majority of chlorine in studied samples exists in organic form. Recommendations to overcome this problem have been developed. 

Metal–Organic Frameworks (MOFs) Containing Adsorbents for Carbon Capture

2022

This research was funded by the European Regional Development Fund project “Innovation of the waste‐to‐energy concept for the low carbon economy: development of novel carbon capture technology for thermochemical processing of municipal solid waste (carbon capture and storage from waste—CCSW)”, grant number 1.1.1.1/19/A/013.

Heavy metals in rivers of Latvia☆

2000

Abstract Total heavy metal concentrations in waters and sediments (HNO 3 digestible Pb, Cu, Co, Ni, Mn, Zn) and their speciation forms in sediments (exchangeable, carbonate bound, iron–manganese oxide bound, organic matter bound and residual) in major and common small watercourses (31 sampling stations) along their flow in Latvia were determined. The metal loads entering the Baltic Sea from Latvia were calculated. Increased metal concentrations were found only in lower reaches of the largest rivers and locally around known industrial pollution sources. Differences in metal concentrations and loads in rivers from different regions of Latvia were related to natural geochemical processes. Meta…

Devonian Clay Modification for the Improvement of Heavy Metal Sorption Properties

2013

Contamination with heavy metals is an important problem as bioaccumulation effects of those are creating direct and indirect hazards to environment and human health. Contaminated soil remediation can be done by various technologies and using of soil amendments is the one. Clay modification experiments were done to study heavy metal sorption from spiked solutions and leaching from contaminated soils. The aim of this paper is to give an overview of Devonian clay modification possibilities in order to improve heavy metal sorption capacity and immobilization options. Modification was done by using Ca, Na salts, HNO 3 (protonated forms), Fe-oxyhydroxide. Research has shown better sorption due to…

Water quality in cutaway peatland lakes in Seda mire, Latvia

2011

Remediation of industrially-milled peatland is an important task in the sustainable management of natural resources. Several approaches for wetland restoration, depending on local climatic and hydrological conditions, topography, physico-chemical properties of peat, as well as peat mining techniques, have been developed worldwide. However, most of the restoration activities include regulation of hydrological regime and surface topography in order to reintroduce typical bog vegetation, especially, Sphagnum cover, and to restore the peatland’s ecosystem close to its original conditions (Gorham and Rochefort, 2003; Farrell and Doyle, 2003; Lamers et al., 2002). In many countries, a significant…

Paradigms on landfill mining: From dump site scavenging to ecosystem services revitalization

2017

For the next century to come, one of the biggest challenges is to provide the mankind with relevant and sufficient resources. Recovery of secondary resources plays a significant role. Industrial processes developed to regain minerals for commodity production in a circular economy become ever more important in the European Union and worldwide. Landfill mining (LFM) constitutes an important technological toolset of processes that regain resources and redistribute them with an accompanying reduction of hazardous influence of environmental contamination and other threats for human health hidden in former dump sites and landfills. This review paper is devoted to LFM problems, historical developm…

Alkylation of ambident indole anion in ionic liquids

2007

AbstractAlkylation of indole salts in different ionic liquids is reported. Ionic liquids increase the alkylation reaction rate of ambident indole anion and reduce the effects of counter ions and/or additives, the alkylation reaction rates being independent of the presence of small amounts of protic solvents or water.

Composite clay sorbents for immobilisation of biomolecules and cells

2015

Genesis of Peat Humic Acid Structure and Properties Within Bog Profiles

2012

Studies of living organic matter humification process are essential for understanding of carbon biogeochemical cycle, and considering this, the aim of this study is to analyse relations between properties of the peat, peat humic acids (HAs) and humification degree on example of analysis of two bog profiles in ombrotrophic bogs to identify the links between peat age, decomposition and humification degree, botanical composition and properties of peat humic acids (elemental, functional composition). The found variability of peat properties is much less than the significant differences in properties of peat-forming living matter, thus stressing the dominant impact of humification process on pea…

Humic Substances for Agricultural Applications: Properties and Challenges

2021

Nowadays, humic substances, the main organic components of soils and many fossil sediments, are becoming a material of wide application in agriculture and many technologies. Elemental, functional and spectral (UV, fluorescence, FTIR, 13C NMR spectra) analysis of industrially produced, as well as reference humic substances demonstrate significant differences in properties of humic substances depending on their origin, and thus, their potential application in agriculture. For authentication of humic substances’ origin, their elemental composition, as well as stable isotope (δC, δN, δO) ratios can be used.

Radioaktivitāte

2023

Mācību grāmatas mērķis ir iepazīstināt lasītāju ar radioaktivitātes fenomenu, jautājumiem par atoma kodola stabilitāti, radioaktīvo elementu, starojuma iedarbību un izmantošanas iespējām. --///-- Šis ir nekomerciāls izdevums, un visi ievietotie attēli ir tikai iepazīšanās,mācīšanās un pētniecības mērķiem, tādi, kurus neaizsargā autortiesības (Public Domain) vai arī kuru autori tos klasificējuši atbilstoši CC BY-NC-SA 4.0 licences lietojumam.

Decarboxylation and alkaline colour fading reactions in presence of humic substances.

2002

Humic substances (HSs) can substantially influence velocity of reactions in the environment as shown on example of decarboxylation and alkaline colour (e.g., malachite green and crystal violet) fading reactions. In colour fading and decarboxylation reactions of 6-nitrobenzisoxazole-3-carboxylic acid HS act as inhibitors, but additions of surfactants change the pattern of reaction. The inhibitory activity of HSs much depends on their origin. The velocity of studied reactions depends also on pH, temperature and concentration of HS used. Possible micellar catalysis mechanism has been suggested.