Sapropelis un tā izmantošanas iespējas

2014

Sapropelis ir ar organiskajām vielām bagāti nogulumi, kas nogulsnējas ūdenstilpēs. Sapropeļa izplatība un plasas izmantosanas iespējas padara to par nozīmīgu dabas resursu, ko var izmantot lauksaimniecībā, dārzkopībā, mežsaimniecībā, lopkopībā, ķīmijas un celtniecības industrijā, balneoloģijā un kosmetoloģijā. Kopējie sapropeļa resursi Latvijā sastāda aptuveni 2 miljardus m3. Sī raksta mērķis ir aplūkot sapropeļa klasifikāciju, veidosanās apstākļus un izmantosanas jomas.

Metals in sediments of lakes in Latvia

1995

Abstract The concentrations and speciation forms of Pb, Cu, Ni, Cd, Zn, and Mn have been determined in sediments from 49 lakes thoroughout Latvia to study the impact of different pollutant sources and to estimate the background pollution level. Regional variation in pollutant distributions of Pb, Cu, and Cd concentrations is due to anthropogenic load. The enrichment of metals in the top layer of sediments is an estimate of the environmental pollution level. In regions with no known pollution sources, this enrichment was not typical. Another factor that determines metal concentrations in sediments is the organic matter production and sedimentation in eutrophic water bodies.

Klimats un ilgtspējīga attīstība

2016

Changes in soil organic matter and soil humic substances following the afforestation of former agricultural lands in the boreal-nemoral ecotone (Latv…

2019

Abstract Abandonment of agricultural land is a widespread process in Northern Europe, which is associated with changes in content and distribution of organic matter in soil, including C stocks. There is insufficient information on changes in soil organic matter properties during afforestation of these lands. The aim of the study was to determine and describe the influence of afforestation on organic carbon (CORG) content and properties of soil organic matter (SOM) in mineral topsoil in the boreo-nemoral ecotone in Latvia. We studied soils in 4 model territories that represented abandoned farmlands and territories where mixed or coniferous forests were established at different times on forme…

Humic substances as catalysts in condensation reactions

2001

Humic substances (HS) demonstrate appreciable impact on the rate of the condensation reactions as shown in the example of the reaction between hydrazine and 4-(dimethylamino)-benzaldhyde in an aquatic environment. The catalytic activity of HS has also been demonstrated in Knoevenagel and Claisen-Schmidt reactions for condensation of carbonyl compounds with CH acids. The aquatic fulvic acids are the most active in these reactions. The velocity of the studied reactions also depends on pH, temperature, the concentration and origin of HS used. A possible micellar and acid-base catalysis mechanism in aquatic media has been suggested.

Stabilization and Solidification Technology Implementation in Latvia: First Studies

2012

Soil and groundwater are environmental compartments that are primarily affected by industrial development with increasing amount of industrial wastes and inadequate dumping of them. A special attention should be paid to heavy metal contamination at least 56 contaminated territories of National priority are known as contaminated with heavy metals in different amount and concentration in Latvia. The stabilization / solidification technology refers to binding of waste contaminants to a more chemically stable form and thus diminishing leaching of contamination. In order to choose the remediation method the pre-investigation in industrial case study area was done in stages: data analysis of prev…

Kūdras resursi un to izmantošanas iespējas

2014

Latvijā un pasaulē kūdra tiek izmantota un iegūta daudz mazākā apjomā nekā tas būtu ekonomiski pamatoti, neapdraudot dabas vērtības un to aizsardzībai paredzētās teritorijas. Rakstā novērtēti Latvijas purvi un kūdras resursi, kā arī to izmantosanas jomas. Tiek sniegts ieskats purvu un kūdras klasifikācijā, kūdras veidosanās procesā un to ietekmējosajos faktoros.

Quality of Lake Ecosystems and its Role in the Spread of Invasive Species

2021

Abstract Lake ecosystems are important elements of hydrological regime, the quality of these ecosystems is affected by anthropogenic actions, and therefore, a variety of organisms, living in these habitats depend on the applied management solutions. Due to human activities freshwater ecosystems suffer from loss of biodiversity and increased eutrophication. Therefore, important aspects related to lake management include knowledge about the water quality, ecosystem response to climate change as well as increased risks of appearance and spreading of invasive species. Water quality, content of oxygen, nutrients, phytoplankton and distribution of macrophytes, including invasive species were anal…

Inhibition of NF-κB pathway in LPS-stimulated THP-1 monocytes and COX-2 activity in vitro by berry pomace extracts from five Vaccinium species

2020

BACKGROUND: Berry processing residues called pomaces are rich in polyphenols, sugars, organic acids, and minerals. Polyphenols are reported to reduce the risk of non-communicable diseases, including cardiovascular diseases, cancer, and diabetes mellitus, owing to their anti-inflammatory activity. OBJECTIVE: We aimed to assess the anti-inflammatory properties of five Vaccinium spp. berry pomace extracts using LPS-stimulated THP-1 monocytes and a COX-2 inhibition assay. METHODS: THP-1 monocytes were pre-incubated with chemically characterized bilberry, blueberry, American cranberry, bog cranberry, and lingonberry pomace extracts following LPS stimulation. NF-κB nuclear translocation was asses…

Sapropeļa kūdras, sapropeļa kokskaidu siltumizolācijas plāksnes un to īpašības

2014

Siltumizolācijas materiāli, kuros par pildvielu tiktu izmantoti vietējie biomasas produkti, bet par saistvielu kalpotu dabiskas izcelsmes saistvielas, piemēram, sapropelis, uzskatāmi par inovatīviem un to pielietošana sekmētu ekoloģiskās būvniecības nozares attīstību. Šādu risinājumu izstrāde ir aktuāla, jo Latvijā ir ievērojami sapropeļa resursi, kuru izmantošanu kavē to nepietiekama izpēte un ekoloģiskās būvniecības nozares intensīva attīstība. Pētījuma mērķis ir iegūt sapropeļa-koksnes, kūdras-koksnes siltumizolācijas plāksnes, noteikt optimālās plātnes sastāva attiecības un raksturot iegūto plātņu īpašības. Veikto pētījumu rezultātā tika noteiktas siltumizolācijas materiālu paraugu mehā…

Development of Peat Processing Methods for Production of Innovative Products

2020

Synthesis or humification of humic substances (HSs) is the second widely applied organic compound transformation process after photosynthesis. Peat decomposition process results in a production of a HSs which has a high demand in agriculture, forestry, and gardening areas. Addition of the KOH is good option for environmental protection and K+ belongs to the nitrogen, potassium and phosphorous (NKP) mineral component. A homogenization process in a customize for commerce, where peat treatment technology was improved with the help of the cavitation effect. This effect was provided with the help of the high-speed mixer-disperser (HSMD) developed at Riga Technical University. Mechanical cavitati…

Clay-Humic Substance Composites for Removal of Pharmaceuticals from Water

2020

Humic substances are the main component of soil organic matter and they actively interact with substances in soils, including pollutants. Humic acid-clay mineral composite materials can be considered as prospective and low-cost sorbents for contaminant removal. The aim of this study is to develop clay mineral and humic acid composite materials and to characterise their possible applications. For this research, montmorillonite, kaolinite and bentonite were saturated with three types of humic substances: technical humic acid from lignite, humic substances extracted from raised bog peat (Latvia) and technical K humate from lignite. Obtained sorbents were characterized using FTIR. The sorption …

The Impact of Humic Substances as Remediation Agents to the Speciation Forms of Metals in Soil

2013

Abstract Humic substances (HS) are the most widespread group of organic substances in natural environment and have high stability. The main terrestrial reserves are found in the form of naturally occurring ore, peat or lignite. The aim of this paper is to study possibilities to use HS as agents for remediation of contaminated with heavy metals soil and impacts of HS of metal speciation forms in it. It has been proved that HS are able to bind to metal ions and change their speciation forms in soils. The ability to form complexes with metal ions depends on the type of soil, type of metal, as well as concentrations of HS in soil. The study was carried out in experimental conditions and analyti…

Sapropel as a Binder: Properties and Application Possibilities for Composite Materials

2015

Recent development trends largely look for possibilities of a wider use of natural materials and local resources. In this perspective, the use of organic rich lake sediment - sapropel - as a binding material in line with other environmentally friendly filling materials can be considered as a challenge. Sapropel itself is a valuable resource with multiple areas of application, for example, medicine, veterinary, agriculture, livestock farming, balneology, cosmetic applications, construction, and its application options have been widely studied in the 20th century in the Baltic countries, Ukraine and Russia. Birch wood fibre and sanding dust, hemp shives, 'Aerosil' are used as a filler and thr…

Dynamics and Impacting Factors of Ice Regimes in Latvia Inland and Coastal Waters

2016

Abstract The sea ice regime is considered to be a sensitive indicator of climate change. This study investigates long-term changes in the ice regimes of the Gulf of Riga along the coast of Latvia in comparison with those of inland waters. The ice regime of the studied region indicates the impact of climate change related to increasing air and sea water temperatures. Ice cover duration on both the sea and inland waters has decreased during recent decades. In addition, long-term records on ice break in the studied region exhibit a pattern of periodic changes in the intensity of ice regime, while trends of the sea ice regime are not consistent between periods of time. Alternating mild and seve…

Evaluation of furanocoumarins from seeds of the wild parsnip (Pastinaca sativa L. s.l.).

2018

Abstract Although the wild parsnip (Pastinaca sativa L. s.l.) fruits are known to contain linear and angular furanocoumarins, the individual components of the seeds have not been fully identified and quantitated, and, in the case of immature seeds, reported. In view of this, the main furanocoumarin compounds were extracted using pyridine, and were isolated using semi-preparative high-performance liquid chromatography. The structural elucidation of isolated compounds was done based on detailed spectral analysis conducted by liquid chromatography–electrospray ionization–mass spectrometry (LC–ESI/MS), 1H and 13C NMR and, where possible, by gas chromatography–mass spectrometry (GC–MS). The quan…

Antimona(V) sorbcijas izpēte uz modificētiem biomateriālu sorbentiem

2014

Antimona(V) savienojumu sorbcijai veikta bioloģiskas izcelsmes sorbentu modificēsana ar dzelzs savienojumiem. Izmantojot dažādas fizikālķīmiskās metodes, noteikti sorbentus raksturojosie parametri. Veikti antimona sorbcijas eksperimenti, izmantojot modificētus – kūdras, skaidu, sūnu, salmu, niedru un smilsu sorbentus, noteikta iegūto rezultātu atbilstība gan Lengmīra, gan Freindliha teorētiskajiem sorbcijas modeļiem. Pētīta sorbcijas atkarība no temperatūras un veikti termodinamisko parametru aprēķini. Konstatēts, ka labākais antimona(V) savienojumu sorbents ir modificēta kūdra, sorbcijas process ir spontāns un endotermisks.

Metal accumulation in sediments and benthic invertebrates in lakes of Latvia

1998

The concentrations of cadmium, lead, nickel and copper in waters, sediments (total metal concentrations and their speciation forms) and benthic macroinvertebrates in 11 lakes of Latvia were determined using atomic absorption spectroscopy. Metal concentrations in lake waters, sediments and biota were compared with water chemistry. Compared to total concentrations, metal speciation forms in sediments were better correlated with respective metal concentrations in invertebrates. Therefore, the evaluation of potential metal bioaccumulation should consider metal speciation. The mean concentrations of trace metals in benthic invertebrates in Latvia were much lower than in other countries, which ca…