Search results for "Sedimenti"

Turve- ja metsätalouden vaikutukset kahden metsäjärven surviaissääskiyhteisöihin : paleolimnologinen tutkimus

2015

Tutkielmassa selvitettiin turve- ja metsätalouden vaikutuksia Martinjärven ja Iso Kivijärven surviaissääskiyhteisöihin paleolimnologisen menetelmän avulla. Järvien sedimenttiprofiileita tarkasteltiin viimeisen 400 vuoden ajalta. Järvet ovat pieniä, matalia humusjärviä ja sijaitsevat Keski-Suomessa Keuruulla vierekkäisillä valuma-alueilla. Surviaissääskiyhteisöjen muutosten perusteella tutkittiin järvien rehevyystason ja humoosisuuden muutoksia ennen ja jälkeen metsätalouden ja turvetuotannon aloittamista. Soiden laajamittainen ojitus metsätalouden käyttöön alkoi 1960-luvulla molempien järvien valuma-alueilla. Martinjärven valuma-alueella aloitettiin lisäksi turpee…

Resistant ammonia-oxidizing archaea endure, but adapting ammonia-oxidizing bacteria thrive in boreal lake sediments receiving nutrient-rich effluents

2018

Climate change along with anthropogenic activities changes biogeochemical conditions in lake ecosystems, modifying the sediment microbial communities. Wastewater effluents introduce nutrients and organic material but also novel microbes to lake ecosystems, simulating forthcoming increases in catchment loadings. In this work, we first used 16s rRNA gene sequencing to study how the overall sediment microbial community responds to wastewater in six boreal lakes. To examine forthcoming changes in the lake biogeochemistry, we focused on the ammonia-oxidizing archaea (AOA) and bacteria (AOB), and examined their functional and compositional community response to wastewater. Although we found the l…

Toxicity of silver nanoparticles to Lumbriculus variegatus is a function of dissolved silver and promoted by low sediment pH

2018

Toxicity of silver nanoparticles (AgNPs) to benthic organisms is a major concern. The use of AgNPs in industry and consumer products leads to increasing release of AgNPs into the aquatic environment—sediments being the major sink. Effects of sediment pH on the toxicity of AgNPs to benthic oligochaeta Lumbriculus variegatus were studied in a 23‐d toxicity test. Artificially prepared sediments (pH 5 and 7) were spiked with varying concentrations of uncoated AgNP, polyvinylpyrrolidone (PVP)‐coated AgNP, and silver nitrate (AgNO3) as dissolved Ag reference. Number of individuals and biomass change were used as endpoints for the toxicity. The toxic effects were related to the bioaccessible conce…

Behaviour of sediment-associated silver nanoparticles and their toxicity to Lumbriculus variegatus

2017

The increasing use of silver nanoparticles (AgNPs) in industry and consumer products results in the increasing environmental concentrations of AgNPs. In the aquatic environment, sediment is the major sink for the AgNPs. The behaviour and toxicity of AgNPs in sediments is largely unknown, and therefore the potential risk to the benthic ecosystems is difficult to predict. The aim of this thesis was to study the toxicity and uptake of uncoated AgNPs (uc-AgNPs) and polyvinylpyrrolidone-coated AgNPs (PVP-AgNPs) to Lumbriculus variegatus in sediment exposures. Also, the association of AgNP-originated dissolved Ag with sediment components was studied using a sequential extraction method. Studies w…

Optical Monitoring of Microplastics Filtrated from Wastewater Sludge and Suspended in Ethanol.

2021

The abundance of microplastics (MPs) in the atmosphere, on land, and especially in water bodies is well acknowledged. In this study, we establish an optical method based on three different techniques, namely, specular reflection to probe the medium, transmission spectroscopy measurements for the detection and identification, and a speckle pattern for monitoring the sedimentation of MPs filtrated from wastewater sludge and suspended in ethanol. We used first Raman measurements to estimate the presence and types of different MPs in wastewater sludge samples. We also used microscopy to identify the shapes of the main MPs. This allowed us to create a teaching set of samples to be characterized …

Kemiallisen metsäteollisuuden uuteaineiden sedimenttihistoria ja sedimenttien riskinarviointi

2008

Exposure assessment of animals to sediments contaminated by pulp and paper mills

2007

Sellu- ja paperiteollisuuden jätevesillä on haittavaikutuksia kaloihin ja muihin vesieläimiin vielä senkin jälkeen, kun vierasaineet ovat hautautuneet vesistön pohjaan osaksi sedimenttiä eli järven pohjaan kerrostunutta ainesta. Vierasaineet voivat vapautua takaisin eliöille saatavaan muotoon, jos vesi sekoittuu voimakkaasti esimerkiksi ruoppauksen tai rajujen myrskyjen yhteydessä. Myös sedimentissä asustaviin pohjaeläimiin kertyy sellu- ja paperiteollisuuden vierasaineita. FM Päivi Meriläinen tutki väitöskirjassaan sellu- ja paperiteollisuuden saastuttamien sedimenttien altistamia vesieläimiä Etelä-Saimaan alueella. Sellu- ja paperiteollisuuden jätevesien haittavaikutuksia kaloihin ja muih…