Search results for "kasautuminen"

Environmental and biological factors are joint drivers of mercury biomagnification in subarctic lake food webs along a climate and productivity gradi…

2021

Subarctic lakes are getting warmer and more productive due to the joint effects of climate change and intensive land-use practices (e.g. forest clear-cutting and peatland ditching), processes that potentially increase leaching of peat- and soil-stored mercury into lake ecosystems. We sampled biotic communities from primary producers (algae) to top consumers (piscivorous fish), in 19 subarctic lakes situated on a latitudinal (69.0-66.5 degrees N), climatic (+3.2 degrees C temperature and +30% precipitation from north to south) and catchment land-use (pristine to intensive forestry areas) gradient. We first tested how the joint effects of climate and productivity influence mercury biomagnific…

Assessing the influence of confounding biological factors when estimating bioaccumulation of PCBs with passive samplers in aquatic ecosystems

2017

Passive samplers are promising surrogates for organisms, mimicking bioaccumulation. However, several biological characteristics disturb the passive partitioning process in organisms by accelerating or restraining bioaccumulation, resulting in species-specific body residues of hydrophobic organic contaminants (HOCs). In addition to site-specific characteristics and HOC concentrations, age, sex, diet, biotransformation capability and habitat-specific characteristics may affect body residues. Two passive sampler types, polyethylene (PE) and polydimethylsiloxane (PDMS) were deployed in a PCB-contaminated freshwater lake water and sediment, respectively, to assess their bioaccumulation predictio…

Empirical Estimation of Accumulation-Induced Change in Gill Net Catchability: Mind the Observation Errors

2015

We analyzed cumulative catches for 24 h gill net exposures divided into 4*6 h, 2*12 h and 1*24 h soak time treatments to estimate the reduction in its catchability due to accumulation of fish. The effects of loss of catch during net lifting, disturbance effect and fouling were eliminated as far as possible to reveal the true effect of accumulation. First we applied simple nonparametric and parametric tests in comparison of treatments. As expected, considerable reduction in catchability took place along with the increase in soak time, indicated by significantly lower total 24 h catches from longer soaks in comparison with shorter ones. The reduction was more pronounced for roach than for per…

Blackfly Larvae (Simulium spp.) Can Intensify Methylmercury Biomagnification in Boreal Food Webs

2020

AbstractGlobal pollution of mercury (Hg) threatens ecosystem and human health. We measured total Hg (THg) and monomethylmercury (MMHg) concentrations in filter-feeding blackfly (Simulium spp.) larvae in the inflows and the outflows of six boreal lakes with no Hg point source pollution. THg in the larvae ranged from 0.03 to 0.31 mg kg−1 dw and MMHg between 0.02 and 0.25 mg kg−1 dw. The proportion of MMHg in the larvae was 74 ± 0.16% and ranged from 43 to 98% of THg, the highest proportions being comparable to those typically found in aquatic predatory insects and fish. We compared the larvae MMHg concentrations to river water quality, catchment land-use, and to size-adjusted lake pike THg da…

Aluetaloustieteen menetelmät liikennejärjestelmän kehittämisen vaikutustarkastelussa

2020

Tässä selvityksessä on arvioitu, voidaanko aluetaloudellisilla tarkasteluilla selvittää liikenneinfrastruktuurien kehittämiseen sekä liikenteen hinnoitteluun ja sääntelyyn liittyvien toimenpiteiden vaikutuksia yrityksille, kuluttajille ja julkiseen talouteen aluetalouksien tasolla. Tulosten mukaan se voidaan tehdä aluetalousmalleilla, joilla kuvataan ja lasketaan kokonaisvaltaisesti talousjärjestelmässä toisistaan riippuvien vaikutusketjujen muutoksia. Liikennejärjestelmän muutosten suorista käyttäjähyödyistä ja -haitoista seuraa välillisesti laajempia taloudellisia vaikutuksia eri markkinoiden välisen vuorovaikutuksen dynamiikassa. Nämä vaikutukset toteutuvat kasautumiseen, työmarkkinoihin…

Poverty, inequality and the Finnish 1860s famine

2016

Perhe, työttömyys ja lama

2002

Huono-osaisuus työmarkkinoilla kasautuu perheisiin. Näin ollen voidaan kärjistetysti sanoa perheen olevan joillekin ongelma. Työttömyyden kasautumisen ongelman alkua on vaikea osoittaa, mutta kyse ei ole yksinomaan ympäristötekijöistä kuten paikalliset työmarkkinat. Perhe olennaisena sosialisaation ja identiteetin muotoutumisen viitekehyksenä levittää tavalla tai toisella myös työttömyysriskiä, toteaa Ilkka Virmasalo väitöstutkimuksessaan. Virmasalo tarkasteli tutkimuksessaan kotitalouteen ja perheeseen liittyvien tekijöiden sekä työttömyyden keskinäistä riippuvuutta erilaisissa taloudellisissa olosuhteissa vuosien 1980-1995 välillä.

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…