Publications by authors named "Thorjørn Larssen"

57 Publications

Improvement in municipal wastewater treatment alters lake nitrogen to phosphorus ratios in populated regions.

Proc Natl Acad Sci U S A 2020 05 8;117(21):11566-11572. Epub 2020 May 8.

Norwegian Institute for Water Research, 0349 Oslo, Norway;

Large-scale and rapid improvement in wastewater treatment is common practice in developing countries, yet this influence on nutrient regimes in receiving waterbodies is rarely examined at broad spatial and temporal scales. Here, we present a study linking decadal nutrient monitoring data in lakes with the corresponding estimates of five major anthropogenic nutrient discharges in their surrounding watersheds over time. Within a continuous monitoring dataset covering the period 2008 to 2017, we find that due to different rates of change in TN and TP concentrations, 24 of 46 lakes, mostly located in China's populated regions, showed increasing TN/TP mass ratios; only 3 lakes showed a decrease. Quantitative relationships between in-lake nutrient concentrations (and their ratios) and anthropogenic nutrient discharges in the surrounding watersheds indicate that increase of lake TN/TP ratios is associated with the rapid improvement in municipal wastewater treatment. Due to the higher removal efficiency of TP compared with TN, TN/TP mass ratios in total municipal wastewater discharge have continued to increase from a median of 10.7 (95% confidence interval, 7.6 to 15.1) in 2008 to 17.7 (95% confidence interval, 13.2 to 27.2) in 2017. Improving municipal wastewater collection and treatment worldwide is an important target within the 17 sustainable development goals set by the United Nations. Given potential ecological impacts on biodiversity and ecosystem function of altered nutrient ratios in wastewater discharge, our results suggest that long-term strategies for domestic wastewater management should not merely focus on total reductions of nutrient discharges but also consider their stoichiometric balance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1073/pnas.1920759117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7261127PMC
May 2020

Assessing Air-Surface Exchange and Fate of Mercury in a Subtropical Forest Using a Novel Passive Exchange-Meter Device.

Environ Sci Technol 2019 05 24;53(9):4869-4879. Epub 2019 Apr 24.

Norwegian Institute for Water Research , NO-0349 Oslo , Norway.

A novel passive exchange meter (EM) device was developed to assess air-surface exchange and leaching of Hg in a forest floor. Flux measurements were carried out in a subtropical forest ecosystem during a full year. Over 40% of the Hg fixed in fresh forest litter was remobilized in less than 60 days in warm and humid conditions as a response to rapid turnover of labile organic matter (OM). A two-block experiment including understory and clearing showed that losses of Hg covaried with seasonal conditions and was significantly affected by forest coverage. The process controlling the bulk loss of total Hg from the litter was volatilization, which typically represented 76-96% of the loss processes (F). The F ranges were 520-1370 and 165-942 ng m d in the understory and clearing, respectively. On a yearly basis, deposition of airborne Hg exceeded total losses by a factor of 2.5 in the clearing and 1.5 in the understory. The vegetation litter in this subtropical forest therefore represented a net sink of atmospheric Hg. This study provided a novel approach to Hg air-soil exchange measurements and further insights on the link between Hg remobilization and OM turnover along with its environmental drivers.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.est.8b06343DOI Listing
May 2019

Modelling Environmental Impacts of Cesium-137 Under a Hypothetical Release of Radioactive Waste.

Bull Environ Contam Toxicol 2019 Jul 1;103(1):69-74. Epub 2019 Apr 1.

Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences NMBU, P.O. Box 5003, 1432, Ås, Norway.

Waste tanks at the nuclear facility located at Sellafield, UK, represent a nuclear source which could release radionuclides to the atmosphere. A model chain which combines atmospheric transport, deposition as well as riverine transport to sea has been developed to predict the riverine activity concentrations of Cs. The source term was estimated to be 9 × 10 TBq of Cs, or 1% of the assumed total Cs inventory of the HAL (Highly Active Liquid) storage tanks. Air dispersion modelling predicted Cs deposition reaching 127 kBq m at the Vikedal catchment in Western Norway. Thus, the riverine transport model predicted that the activity concentration of Cs in water at the river outlet could reach 9000 Bq m in the aqueous phase and 1000 Bq kg in solid phase at peak level. The lake and river reaches showed different transport patterns due to the buffering effects caused by dilution and slowing down of water velocity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00128-019-02601-5DOI Listing
July 2019

Dynamic Modeling and Target Loads of Sulfur and Nitrogen for Surface Waters in Finland, Norway, Sweden, and the United Kingdom.

Environ Sci Technol 2019 05 8;53(9):5062-5070. Epub 2019 Apr 8.

Centre for Ecology & Hydrology , Bangor LL57 2UW , United Kingdom.

The target load concept is an extension of the critical load concept of air pollution inputs to ecosystems. The advantage of target loads over critical loads is that one can define the deposition and the point in time (target year) when the critical (chemical) limit is no longer violated. This information on the timing of recovery requires dynamic modeling. Using a well-documented dynamic model, target loads for acidic deposition were determined for 848 surface waters across Finland, Norway, Sweden, and the United Kingdom for the target year 2050. In the majority of sites ( n = 675), the critical ANC-limit was predicted to be achieved by 2050; however, for 127 sites, target loads were determined. In addition, 46 sites were infeasible, i.e., even a reduction of anthropogenic deposition to zero would not achieve the limit by 2050. The average maximum target load for sulfur was 38% lower than the respective critical load across the study lakes ( n = 127). Target loads on a large regional scale can inform effects-based emission reduction policies; the current assessment suggests that reductions beyond the Gothenburg Protocol are required to ensure surface water recovery from acidification by 2050.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.est.8b06356DOI Listing
May 2019

Weir building: A potential cost-effective method for reducing mercury leaching from abandoned mining tailings.

Sci Total Environ 2019 Feb 12;651(Pt 1):171-178. Epub 2018 Sep 12.

Norwegian Institute for Water Research, Gaustadalleen 21, 0349 Oslo, Norway.

To mitigate mercury (Hg) pollution and reduce Hg downstream transportation, a weir was designed by a river system that had been inflicted by leachate from the slagheap of the Yanwuping Hg mine in Wanshan Hg mining area. A whole year monitoring of Hg species was conducted, and the efficiency of Hg reduction by the weir application was evaluated. The Hg concentrations in the river water were significantly higher in the wet season than in the dry season. Waterflow was confirmed to be the main driving factor for Hg mobilization and transportation, and an episode study revealed that most Hg was released in times of storms. Increased monitoring and preventive maintenance measures need to be taken on barriers in advance of storms. A large proportion of the total Hg (THg) and methylmercury (MeHg) is associated to particles. During the study period, approximately 412 g THg and 4.04 g total MeHg (TMeHg) were released from the YMM slagheap, of which 167 g THg and 1.15 g TMeHg were retained by the weir. Annually, 40.4% THg and 38.4% TMeHg was retained by the weir. Weir construction is considered as a potential cost-effective measure to mitigate Hg in river water and should be promoted and extended in the future after optimization.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2018.09.150DOI Listing
February 2019

The organic pollutant status of rivers in Bosnia and Herzegovina as determined by a combination of active and passive sampling methods.

Environ Monit Assess 2018 Apr 15;190(5):283. Epub 2018 Apr 15.

Norwegian Institute for Water Research (NIVA), Oslo Centre for Interdisciplinary Environmental and Social Research (CIENS), Gaustadalléen 21, 0349, Oslo, Norway.

There is an overall lack of data concerning the pollution status of Bosnia Herzegovina, which is confounded by fragmented national environmental management. The present study aimed to provide some initial data for concentrations of priority substances in two major Bosnian Rivers, using two types of passive sampler (PS) as well as by using high volume water sampling (HVWS). Overall, concentrations of most persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs) and legacy pesticides, were shown to be low. However, around the town of Doboj on the Bosna River, concentrations of polycyclic aromatic hydrocarbons (PAH) breached European standards for several compounds and reached 67 ng L for freely dissolved concentrations and 250 ng L for total concentrations. In general, contamination was lower in the Neretva River compared to the Bosna, although for brominated diphenyl ethers (PBDEs), results suggested an active source of PBDEs at one location based on the ratio of congeners 47 and 99. Direct comparisons between the different sampling techniques used are not straightforward, but similar patterns of PAH contamination were shown by HVWS and PS in the Bosna River. There are both scientific and practical considerations when choosing which type of sampling technique to apply, and this should be decided based on the goals of each individual study.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10661-018-6667-6DOI Listing
April 2018

Mercury in fish from Norwegian lakes: The complex influence of aqueous organic carbon.

Sci Total Environ 2018 Jun 3;627:341-348. Epub 2018 Feb 3.

Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, N-0349 Oslo, Norway.

Mercury (Hg) concentrations in water and biota are often positively correlated to organic matter (OM), typically measured as total or dissolved organic carbon (TOC/DOC). However, recent evidence suggests that higher OM concentrations inhibit bioaccumulation of Hg. Here, we test how TOC impacts the Hg accumulation in fish in a synoptic study of Methyl-Hg (MeHg) in water and total Hg (THg) in perch (Perca fluviatilis) in 34 boreal lakes in southern Norway. We found that aqueous MeHg (r = 0.49, p < 0.0001) and THg (r = 0.69, p < 0.0001), and fish THg (r = 0.26, p < 0.01) were all positively related with TOC. However, we found declining MeHg bioaccumulation factors (BAF) for fish with increasing TOC concentrations. The significant correlation between fish THg concentrations and aqueous TOC suggests that elevated fish Hg levels in boreal regions are associated with humic lakes. The declining BAF with increasing TOC suggest that increased OM promotes increased aqueous Hg concentrations, but lowers relative MeHg bioaccumulation. A mechanistic understanding of the response from OM on BAF might be found in the metal-complexation properties of OM, where OM complexation of metals reduces their bioavailability. Hence, suggesting that MeHg bioaccumulation becomes less effective at higher TOC, which is particularly relevant when assessing potential responses of fish Hg to predicted future changes in OM inputs to boreal ecosystems. Increased browning of waters may affect fish Hg in opposite directions: an increase of food web exposure to aqueous Hg, and reduced bioavailability of Hg species. However, the negative relationship between BAF and TOC is challenging to interpret, and carries a great deal of uncertainty, since this relationship may be driven by the underlying correlation between TOC and MeHg (i.e. spurious correlations). Our results suggest that the trade-off between Hg exposure and accumulation will have important implications for the effects of lake browning on Hg transport, bioavailability, and trophodynamics.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2018.01.252DOI Listing
June 2018

Monitoring Effect of SO Emission Abatement on Recovery of Acidified Soil and Streamwater in Southwest China.

Environ Sci Technol 2017 Sep 22;51(17):9498-9506. Epub 2017 Aug 22.

State Key laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University , Beijing 100084, China.

Following Europe and North America, East Asia has become a global hotspot of acid deposition, with very high deposition of both sulfur (S) and nitrogen (N) occurring in large areas in southwest and southeast China. Great efforts have been made in reducing national emission of sulfur dioxide (SO) since 2006 in China. However, the total emission of nitrogen oxides (NOx) continued to increase until 2011. To evaluate the effects of SO and NOx emission abatement on acid deposition and acidification of soil and water, we monitored the chemical composition of throughfall, soil water, and streamwater from 2001 to 2013 in a small, forested catchment near Chongqing city in Southwestern China. The deposition of S decreased significantly, whereas N deposition increased in the recent years. This clearly showed the effect of SO abatement but not of NOx. Overall the rate of acid deposition was reduced. However, there was delay in the recovery of soil and surface water from acidification, probably due to desorption of previously stored sulfate (SO) and increase in nitrate (NO) leaching from soil. The average acid input by N transformations has greatly exceeded the H input directly by atmospheric deposition. The reversal of acidification with an increase in pH of soil water, requires additional abatement of emissions of both SO and NOx.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.est.7b01147DOI Listing
September 2017

Is surface water acidification a serious regional issue in China?

Sci Total Environ 2017 Apr 1;584-585:783-790. Epub 2017 Feb 1.

State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China. Electronic address:

Acidic deposition used to cause severe surface water acidification in Europe and the North America, but no damage of surface water acidification was reported under continuous heavy acid deposition in China. We present the first detailed study on regional surface water acidification in southern and northeastern China based on a survey of 255 forested headwater streams, which were investigated during 2010-2015 to explore the status and mechanism of surface water acidification. South China has a subtropical climate with high acid deposition, whereas northeast China is located in a cold temperature zone with relatively low acid deposition. High pH and acid neutralizing capacity (ANC) were observed for almost all of the streams, indicating that surface water acidification may not be a serious regional issue in China both at present and in the future. In northeast China, where soil types are similar in low weathering rate to those in Northern Europe and North America, the ANC of surface waters was lower than that in South China, indicating a higher acid-sensitivity of the surface water. In comparison, the high pH and ANC of streams in southwest China resulted from high soil weathering and atmospheric calcium (Ca) deposition, despite elevated atmospheric acid inputs due to the high sulfur (S) and nitrogen (N) deposition. Comparison of stream nitrate (NO) and sulfate (SO) concentrations with modeled N and S deposition showed significant N and possible S sinks in the catchments in south China, probably due to denitrification of NO in groundwater discharge zone and SO adsorption by acid soils respectively, which may also buffer the acidifying effect of S and N depositions. It seems that considerable NO leaching to stream waters does not occur in China unless N deposition is higher than 1.8keq·ha·yr (2.50g N·m·yr) (or greater values in certain regions).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2017.01.116DOI Listing
April 2017

A Holistic Perspective Is Needed To Ensure Success of Minamata Convention on Mercury.

Environ Sci Technol 2017 02 23;51(3):1070-1071. Epub 2017 Jan 23.

Norwegian Institute for Water Research, Oslo, 0349, Norway.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.est.6b06309DOI Listing
February 2017

Mercury Flows in China and Global Drivers.

Environ Sci Technol 2017 01 13;51(1):222-231. Epub 2016 Dec 13.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University , Beijing 100084, China.

Mercury (Hg) pollution control has become an urgent need at global and national scales. This study, for the first time, comprehensively examines Hg flows in Mainland China and uncovers domestic and external causal drivers of China's Hg emissions/releases. Results show that China's Hg input reaches 2643 t in 2010. China discharges 1368 t of Hg to the environment (to air, 633 t; water, 84 t; and land, 651 t). Embedded Hg transfers across production sectors via waste/byproduct flows reduce Hg releases to land, but lead to secondary Hg emissions to air. Such revelations of embedded Hg transfers adjusts China's comprehensive Hg control that would otherwise only tackle primary emitters. Domestic consumption causes 67% of China's Hg emissions/releases, and external consumption induces the remaining 33%. Besides traditional production-side Hg control measures, demand-side measures and international joint efforts are required to effectively combat Hg pollution. Uncovering embedded and embodied Hg flows within the global economy can assist a paradigm shift necessary to make real progress in global Hg control and the implementation of the Minamata Convention on Mercury.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.est.6b04094DOI Listing
January 2017

Atmospheric S and N deposition relates to increasing riverine transport of S and N in southwest China: Implications for soil acidification.

Environ Pollut 2016 Nov 30;218:1191-1199. Epub 2016 Aug 30.

Air Environmental Modeling and Pollution Controlling Key Laboratory of Sichuan Education Institutes, College of Resources and Environment, Chengdu University of Information Technology, Chengdu 610225, China.

Following Europe and North America, East Asia has become a global hotspot for acid deposition, with very high deposition of both sulfur (S) and nitrogen (N) occurring in large areas of southwest and southeast China. This study shows that the outflow flux of sulfate (SO) in three major tributaries of the Upper Yangtze River in the Sichuan Basin in southwest China has been increasing over the last three decades, which implies the regional soil acidification caused by increasing sulfur dioxide (SO) emissions. Since 2005, the outflow of SO to the Upper Yangtze River from the Sichuan Basin has even reached the atmospheric SO emission from the basin. In contrast to S emissions, the rapid increase in nitrogen (N) emissions, including nitrogen oxides (NOx) and ammonia (NH), have resulted in only a slight increase in nitrate (NO) concentrations in surface waters, indicating a large retention of N in the basin. Although N deposition currently contributes much less than S to soil acidification in this area, it is possible that catchments receiving a high input of N may be unable to retain a large fraction of the N deposition over long periods.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.envpol.2016.08.075DOI Listing
November 2016

Material Flow for the Intentional Use of Mercury in China.

Environ Sci Technol 2016 Mar 15;50(5):2337-44. Epub 2016 Feb 15.

Norwegian Institute for Water Research, Oslo, 0349, Norway.

Intentional use of mercury (Hg) is an important contributor to the release of Hg into the environment. This study presents the first inventory of material flow for intentional use of Hg in China. The total amount of Hg used in China increased from 803 ± 95 tons in 2005 to its peak level of 1272 ± 110 tons in 2011. Vinyl chloride monomer (VCM) production is the largest user of Hg, accounting for over 60% of the total demand. As regulations on Hg content in products are tightening globally against the background of the Minamata Convention, the total demand will decrease. Medical devices will likely still use a significant amount of Hg and become the second largest user of Hg if no proactive measures are taken. Significant knowledge gaps exist in China for catalyst recycling sector. Although more than half of the Hg used is recycled, this sector has not drawn enough attention. There are also more than 200 tons of Hg that had unknown fates in 2011; very little information exists related to this issue. Among the final environmental fates, landfill is the largest receiver of Hg, followed by air, water, and soil.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.est.5b04998DOI Listing
March 2016

Assessment of contaminant fate in catchments using a novel integrated hydrobiogeochemical-multimedia fate model.

Sci Total Environ 2016 Feb 8;544:553-63. Epub 2015 Dec 8.

Norwegian Institute for Water Research, NO-0349, Oslo, Norway.

Models for pollution exposure assessment typically adopt an overly simplistic representation of geography, climate and biogeochemical processes. This strategy is unsatisfactory when high temporal resolution simulations for sub-regional spatial domains are performed, in which parameters defining scenarios can vary interdependently in space and time. This is, for example, the case when assessing the influence of biogeochemical processing on contaminant fate. Here we present INCA-Contaminants, the Integrated Catchments model for Contaminants; a new model that simultaneously and realistically solves mass balances of water, carbon, sediments and contaminants in the soil-stream-sediment system of catchments and their river networks as a function of climate, land use/management and contaminant properties. When forced with realistic climate and contaminant input data, the model was able to predict polychlorinated biphenyls (PCBs) concentrations in multiple segments of a river network in a complex landscape. We analyzed model output sensitivity to a number of hydro-biogeochemical parameters. The rate of soil organic matter mineralization was the most sensitive parameter controlling PCBs levels in river water, supporting the hypothesis that organic matter turnover rates will influence re-mobilization of previously deposited PCBs which had accumulated in soil organic matrix. The model was also used to project the long term fate of PCB 101 under two climate scenarios. Catchment diffuse run-off and riverine transport were the major pathways of contaminant re-mobilization. Simulations show that during the next decade the investigated boreal catchment will shift from being a net atmospheric PCB sink to a net source for air and water, with future climate perturbation having little influence on this trend. Our results highlight the importance of using credible hydro-biogeochemical simulations when modeling the fate of hydrophobic contaminants.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2015.11.087DOI Listing
February 2016

Perfluoroalkyl substances (PFAS) in river and ground/drinking water of the Ganges River basin: Emissions and implications for human exposure.

Environ Pollut 2016 Jan;208(Pt B):704-13

Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, Oslo 0349, Norway; Research Centre for Toxic Compounds in the Environment (RECETOX), Masaryk University, Brno 62500, Czech Republic. Electronic address:

Many perfluoroalkyl substances (PFAS) are ubiquitous environmental contaminants. They have been widely used in production processes and daily-use products or may result from degradation of precursor compounds in products or the environment. India, with its developing industrialization and population moving from traditional to contemporary lifestyles, represents an interesting case study to investigate PFAS emission and exposure along steep environmental and socioeconomic gradients. This study assesses PFAS concentrations in river and groundwater (used in this region as drinking water) from several locations along the Ganges River and estimates direct emissions, specifically for PFOS and PFOA. 15 PFAS were frequently detected in the river with the highest concentrations observed for PFHxA (0.4-4.7 ng L(-1)) and PFBS (
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.envpol.2015.10.050DOI Listing
January 2016

Melting Himalayan glaciers contaminated by legacy atmospheric depositions are important sources of PCBs and high-molecular-weight PAHs for the Ganges floodplain during dry periods.

Environ Pollut 2015 Nov 24;206:588-96. Epub 2015 Aug 24.

Norwegian Institute for Water Research (NIVA), Gaustadalleen 21, Oslo, 0349, Norway.

Melting glaciers are natural redistributors of legacy airborne pollutants, affecting exposure of pristine proglacial environments. Our data shows that melting Himalayan glaciers can be major contributors of polychlorinated biphenyls (PCBs) and high-molecular-weight polycyclic aromatic hydrocarbons (PAHs) for surface water in the Gangetic Plain during the dry season. Glacial emissions can exceed in some cases inputs from diffuse sources within the catchment. We analyzed air, deposition and river water in several sections along the Ganges River and its major headwaters. The predominant glacial origin of these contaminants in the Himalayan reach was demonstrated using air-water fugacity ratios and mass balance analysis. The proportion of meltwater emissions compared to pollutant discharge at downstream sections in the central part of the Gangetic Plain was between 2 and 200%. By remobilizing legacy pollutants from melting glaciers, climate change can enhance exposure levels over large and already heavily impacted regions of Northern India.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.envpol.2015.08.012DOI Listing
November 2015

Pesticide levels and environmental risk in aquatic environments in China--A review.

Environ Int 2015 Aug 25;81:87-97. Epub 2015 May 25.

NIVA (Norwegian Institute for Water Research), Gaustadalléen 21, 0342 Oslo, Norway.

China is one of the largest producers and consumers of pesticides in the world today. Along with the widespread use of pesticides and industrialization, there is a growing concern for water quality. The present review aims to provide an overview of studies on pesticides in aquatic environments in China. The levels in the water, sediment and biota were scored according to a detailed environmental classification system based on ecotoxicological effect, which is therefore a useful tool for assessing the risk these compounds pose to the aquatic ecosystem. Our review reveals that the most studied areas in China are the most populated and the most developed economically and that the most frequently studied pesticides are DDT and HCH. We show maps of where studies have been conducted and show the ecotoxicological risk the pesticides pose in each of the matrices. Our review pinpoints the need for biota samples to assess the risk. A large fraction of the results from the studies are given an environmental classification of "very bad" based on levels in biota. In general, the risk is higher for DDT than HCH. A few food web studies have also been conducted, and we encourage further study of this important information from this region. The review reveals that many of the most important agricultural provinces (e.g., Henan, Hubei and Hunan) with the largest pesticide use have been the subject of few studies on the environmental levels of pesticides. We consider this to be a major knowledge gap for understanding the status of pesticide contamination and related risk in China. Furthermore, there is also a lack of studies in remote Chinese environments, which is also an important knowledge gap. The compounds analyzed and reported in the studies represent a serious bias because a great deal of attention is given to DDT and HCH, whereas the organophosphate insecticides dominating current use are less frequently investigated. For the future, we point to the need for an organized monitoring plan designed according to the knowledge gaps in terms of geographical distribution, compounds included, and risks.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.envint.2015.04.013DOI Listing
August 2015

Effects of photodemethylation on the methylmercury budget of boreal Norwegian lakes.

Environ Toxicol Chem 2015 Jun 9;34(6):1213-23. Epub 2015 Apr 9.

Norwegian Institute for Water Research, Oslo, Norway.

Methylmercury (MeHg) concentrations in freshwater fish from southeastern Norway continue to increase, highlighting the need for a comprehensive understanding of MeHg sources, cycling, and degradation in the aquatic environment. The authors assessed the importance of photodemethylation in the MeHg budget of 4 Norwegian lakes. Photodemethylation rates were determined using incubation experiments with MeHg-spiked natural lake water. The authors determined full-spectrum exposure rates at all study sites and waveband-specific rates (photosynthetically active radiation, ultraviolet-A radiation, and ultraviolet-B radiation) at 1 clear-water (Sognsvann) and 1 humic (Langtjern) site. No significant differences in photodemethylation rates between the sites were found, and the authors' observed rates agreed with available literature for lake and wetland waters. The authors paired experimentally derived photodemethylation rates with lake-specific incident irradiation, light attenuation, and MeHg concentrations to estimate MeHg loss through photodemethylation for the study sites. For Langtjern, losses through photodemethylation equalled 27% of total annual inputs, highlighting the importance of photodemethylation in the MeHg budget. Furthermore, the authors assessed how changes in terrestrial dissolved organic carbon (DOC) exported to freshwaters and climate-driven reductions in ice cover duration may affect MeHg losses through photodemethylation. Results suggest that future increases in DOC may lead to higher aqueous MeHg concentrations in boreal lakes due to increased DOC-associated MeHg inputs paired with significant decreases in the loss of MeHg through photodemethylation due to increased light attenuation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/etc.2923DOI Listing
June 2015

Mercury analysis in hair: Comparability and quality assessment within the transnational COPHES/DEMOCOPHES project.

Environ Res 2015 Aug 4;141:24-30. Epub 2014 Dec 4.

Norwegian Institute for Water Research (NIVA), Norway.

Human biomonitoring (HBM) is an effective tool for assessing actual exposure to chemicals that takes into account all routes of intake. Although hair analysis is considered to be an optimal biomarker for assessing mercury exposure, the lack of harmonization as regards sampling and analytical procedures has often limited the comparison of data at national and international level. The European-funded projects COPHES and DEMOCOPHES developed and tested a harmonized European approach to Human Biomonitoring in response to the European Environment and Health Action Plan. Herein we describe the quality assurance program (QAP) for assessing mercury levels in hair samples from more than 1800 mother-child pairs recruited in 17 European countries. To ensure the comparability of the results, standard operating procedures (SOPs) for sampling and for mercury analysis were drafted and distributed to participating laboratories. Training sessions were organized for field workers and four external quality-assessment exercises (ICI/EQUAS), followed by the corresponding web conferences, were organized between March 2011 and February 2012. ICI/EQUAS used native hair samples at two mercury concentration ranges (0.20-0.71 and 0.80-1.63) per exercise. The results revealed relative standard deviations of 7.87-13.55% and 4.04-11.31% for the low and high mercury concentration ranges, respectively. A total of 16 out of 18 participating laboratories the QAP requirements and were allowed to analyze samples from the DEMOCOPHES pilot study. Web conferences after each ICI/EQUAS revealed this to be a new and effective tool for improving analytical performance and increasing capacity building. The procedure developed and tested in COPHES/DEMOCOPHES would be optimal for application on a global scale as regards implementation of the Minamata Convention on Mercury.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.envres.2014.11.014DOI Listing
August 2015

Seasonal and year-to-year variation of mercury concentration in perch (Perca fluviatilis) in boreal lakes.

Environ Toxicol Chem 2014 Dec 22;33(12):2661-70. Epub 2014 Sep 22.

Norwegian Institute for Water Research, Oslo, Norway; Department of Chemistry, University of Oslo, Oslo, Norway.

The authors examined the seasonal and year-to-year variations of mercury (Hg) concentrations in populations of perch (Perca fluviatilis) from 2 boreal freshwater lakes in southeast Norway. Fish Hg concentrations were determined seasonally (spring, summer, and autumn) over 3 yr (2010, 2011, and 2012) to test the hypothesis that there are substantial changes in fish Hg concentrations during the year (seasonal variation) as well as annually. Concentrations were significantly (p < 0.0001) different in the 2 study lakes, with mean seasonal concentrations varying from 0.24 mg/kg to 0.36 mg/kg and from 0.29 mg/kg to 0.37 mg/kg, respectively. The Hg concentrations of both perch populations showed significant year-to-year (p < 0.0001) and seasonal variation (p < 0.01). The changing fish Hg concentrations were 25% and 28% (2010-2011) and 17% and 0% (2011-2012) in the 2 lakes over the 3 yr, respectively. The results demonstrate how the significant year-to-year increase is, among other variables, related to changes in trophic position, shown through stable nitrogen (δ(15)N) isotope data. The seasonal variation is related to summer growth dilution. The results highlight the clear need for yearly studies of fish Hg concentrations, rather than the 3-yr cycle suggested by current European policy through the Water Framework Directive. The lack of yearly sampling may result in erroneous conclusions regarding fish Hg concentration time trends.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/etc.2733DOI Listing
December 2014

The legal framework to manage chemical pollution in India and the lesson from the Persistent Organic Pollutants (POPs).

Sci Total Environ 2014 Aug 4;490:733-47. Epub 2014 Jun 4.

Norwegian Institute for water Research (NIVA), Gaustadalleen 21, Oslo 0349, Norway.

India's rapid agro-economic growth has resulted into many environmental issues, especially related to chemical pollution. Environmental management and control of toxic chemicals have gained significant attention from policy makers, researchers, and enterprises in India. The present study reviews the policy and legal and non-regulatory schemes set in place in this country during the last decades to manage chemical risk and compares them with those in developed nations. India has a large and fragmented body of regulation to control and manage chemical pollution which appears to be ineffective in protecting environment and human health. The example of POPs contamination in India is proposed to support such a theory. Overlapping of jurisdictions and retrospectively approached environmental policy and risk management currently adopted in India are out of date and excluding Indian economy from the process of building and participating into new, environmentally-sustainable market spaces for chemical products. To address these issues, the introduction of a new integrated and scientifically-informed regulation and management scheme is recommended. Such scheme should acknowledge the principle of risk management rather than the current one based on risk acceptance. To this end, India should take advantage of the experience of recently introduced chemical management regulation in some developed nations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2014.05.043DOI Listing
August 2014

Understanding the paradox of selenium contamination in mercury mining areas: high soil content and low accumulation in rice.

Environ Pollut 2014 May 13;188:27-36. Epub 2014 Feb 13.

Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, 0349 Oslo, Norway.

Rice is an important source of Se for billions of people throughout the world. The Wanshan area can be categorized as a seleniferous region due to its high soil Se content, but the Se content in the rice in Wanshan is much lower than that from typical seleniferous regions with an equivalent soil Se level. To investigate why the Se bioaccumulation in Wanshan is low, we measured the soil Se speciation using a sequential partial dissolution technique. The results demonstrated that the bioavailable species only accounted for a small proportion of the total Se in the soils from Wanshan, a much lower quantity than that found in the seleniferous regions. The potential mechanisms may be associated with the existence of Hg contamination, which is likely related to the formation of an inert Hg-Se insoluble precipitate in soils in Wanshan.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.envpol.2014.01.012DOI Listing
May 2014

Environment and human exposure to persistent organic pollutants (POPs) in India: a systematic review of recent and historical data.

Environ Int 2014 May 11;66:48-64. Epub 2014 Feb 11.

Norwegian Institute for Water Research, Gaustadalleen 21, Oslo 0349, Norway.

Persistent organic pollutants (POPs) have been used in a wide range of agricultural and industrial commodities, resulting in vigorous deterioration of environment and human health. A number of studies on the occurrence of POPs confirm their presence in various environmental compartments and human body. In order to deal with this global concern, India has recently prepared the National Implementation Plan (NIP) of the Stockholm Convention. Common beliefs point at India as a hot spot of POP contamination and human exposure; however no systematic analysis was ever performed so far considering all available past data on POP occurrence. This review aims to examine the distribution pattern of POPs in multicompartment environment and human samples, meta-analysis of time trends in exposure levels to environment and humans, and cross country comparison of POP contamination with China. Based on this review, it can be concluded that the Indian environment and human population are highly contaminated by DDTs and HCHs; however scarcity of data on other POPs makes it challenging to assess their nationwide human and environmental exposure. No evidence of a general decline in DDT and HCH residues in the environment and human body come out from the meta-analysis of time trend. While comparing contamination levels between India and China, tendency towards decline in POP contamination is visible in China, unlike India.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.envint.2014.01.022DOI Listing
May 2014

Environmental factors influencing mercury speciation in Subarctic and Boreal lakes.

Sci Total Environ 2014 Apr 26;476-477:336-45. Epub 2014 Jan 26.

Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, N-0349 Oslo, Norway.

Environmental drivers of total mercury (TotHg) concentrations, methylmercury (MeHg) concentrations, and MeHg fractions (a proxy for methylation potential, expressed as %MeHg) were assessed in a synoptic study of 51 lakes in southeast (Boreal) and northeast (Subarctic) Norway. Concentrations of TotHg and MeHg ranged between 0.5-6.6 ng/L and <0.02-0.70 ng/L, respectively. The lakes span wide ranges of explanatory environmental variables, including water chemistry, catchment characteristics, climate conditions, and atmospheric deposition of Hg, sulphur and nitrogen (N). Dissolved organic matter (DOM), measured as total organic carbon (TOC), was the variable most strongly correlated with TotHg (r(2)=0.76) and MeHg (r(2)=0.64) concentrations. Lakes in the Subarctic region had significantly lower TotHg and MeHg concentrations, and %MeHg than lakes in the Boreal region (p<0.01), implying a lower aquatic food web exposure of aqueous Hg species in Subarctic Norway than in the Boreal lakes. Statistical modelling (partial least squares) using data from the Boreal lakes produced models explaining 82%, 75% and 50% of the spatial variation of TotHg and MeHg concentrations and %MeHg, respectively. After TOC, the most significant explanatory variables were N availability, base cation status, and lake and catchment size. We conclude that a key process driving TotHg concentrations is DOM as a transport vector, while the role of DOM for MeHg and %MeHg is likely related to a combination of transport and DOM as a substrate for methylation. Also, negative correlations between MeHg, and catchment and lake size are consistent with in-lake and in-stream de-methylation processes. The statistical relationship suggests that N availability exerts a positive contribution on concentrations of MeHg and %MeHg.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2014.01.030DOI Listing
April 2014

New insights into traditional health risk assessments of mercury exposure: implications of selenium.

Environ Sci Technol 2014 Jan 8;48(2):1206-12. Epub 2014 Jan 8.

Norwegian Institute for Water Research (NIVA) , Gaustadalléen 21, 0349 Oslo, Norway.

There is increasing evidence that selenium (Se) has a significant effect on mercury (Hg) toxicology; however, Hg exposure risk assessments usually consider only the amount of Hg present in the environment or in food. On the basis of the present understanding of mechanisms of interaction between Se and Hg, the physiology/toxicology of Se, and the toxicology of Hg, we propose a new criterion for Se/Hg exposure assessment. This criterion, which is based on Se-Hg interactions, considers not only the toxicological consequences of Hg exposure but also the benefits and/or adverse effects of Se intake, especially the adverse effects related to a Se deficiency/excess. According to an illustrative assessment based on the new criterion and nine existing criteria, large knowledge gaps in the traditional assessments of exposure to Hg and/or Se were found, including those that assessed the interactions between Hg and Se. These results suggest that future assessments of Hg exposure (or Se intake) should include both Se and Hg.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/es4051082DOI Listing
January 2014

Atmospheric mercury inputs in montane soils increase with elevation: evidence from mercury isotope signatures.

Sci Rep 2013 Nov 25;3:3322. Epub 2013 Nov 25.

1] State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002, China [2] Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, 0349 Oslo, Norway [3].

The influence of topography on the biogeochemical cycle of mercury (Hg) has received relatively little attention. Here, we report the measurement of Hg species and their corresponding isotope composition in soil sampled along an elevational gradient transect on Mt. Leigong in subtropical southwestern China. The data are used to explain orography-related effects on the fate and behaviour of Hg species in montane environments. The total- and methyl-Hg concentrations in topsoil samples show a positive correlation with elevation. However, a negative elevation dependence was observed in the mass-dependent fractionation (MDF) and mass-independent fractionation (MIF) signatures of Hg isotopes. Both a MIF (Δ(199)Hg) binary mixing approach and the traditional inert element method indicate that the content of Hg derived from the atmosphere distinctly increases with altitude.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/srep03322DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3839031PMC
November 2013

First report of a Chinese PFOS alternative overlooked for 30 years: its toxicity, persistence, and presence in the environment.

Environ Sci Technol 2013 Sep 29;47(18):10163-70. Epub 2013 Aug 29.

State Key Joint Laboratory of Environment Simulation and Pollution Control (SKJLESPC), School of Environment, POPs Research Centre, Tsinghua University , Beijing 100084, P.R. China.

This is the first report on the environmental occurrence of a chlorinated polyfluorinated ether sulfonate (locally called F-53B, C8ClF16O4SK). It has been widely applied as a mist suppressant by the chrome plating industry in China for decades but has evaded the attention of environmental research and regulation. In this study, F-53B was found in high concentrations (43-78 and 65-112 μg/L for the effluent and influent, respectively) in wastewater from the chrome plating industry in the city of Wenzhou, China. F-53B was not successfully removed by the wastewater treatments in place. Consequently, it was detected in surface water that receives the treated wastewater at similar levels to PFOS (ca. 10-50 ng/L) and the concentration decreased with the increasing distance from the wastewater discharge point along the river. Initial data presented here suggest that F-53B is moderately toxic (Zebrafish LC50-96 h 15.5 mg/L) and is as resistant to degradation as PFOS. While current usage is limited to the chrome plating industry, the increasing demand for PFOS alternatives in other sectors may result in expanded usage. Collectively, the results of this work call for future assessments on the effects of this overlooked contaminant and its presence and fate in the environment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/es401525nDOI Listing
September 2013

Air-pollution emission control in China: impacts on soil acidification recovery and constraints due to drought.

Sci Total Environ 2013 Oct 27;463-464:1031-41. Epub 2013 Jul 27.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China. Electronic address:

The Chinese government has established compulsory targets to reduce sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions by 8% and 10%, respectively, during 2010-2015. In this study, the effect of the policy was evaluated by predicting the recovery of acidified forest soil in Chongqing, an area severely impacted by acid rain in southwest China. Since precipitation has decreased significantly in this area in recent years, the impact of drought on soil acidification was also considered. A dynamic acidification model, MAGIC, was used to predict future trends in soil chemistry under different scenarios for deposition reduction as well as drought. We found that the current regulation of SO2 emission abatement did not significantly increase soil water pH values, the Ca2+ to Al3+ molar ratio (Ca/Al), or soil base saturation to the level of 2000 before 2050. NOx emission control would have less of an effect on acidification recovery, while emission reduction of particulate matter could offset the benefits of SO2 reduction by greatly decreasing the deposition of base cations, particularly Ca(2+). Continuous droughts in the future might also delay acidification recovery. Therefore, more stringent SO2 emission control should be implemented to facilitate the recovery of seriously acidified areas in China.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2013.06.108DOI Listing
October 2013

Critical evaluation of a new passive exchange-meter for assessing multimedia fate of persistent organic pollutants at the air-soil interface.

Environ Pollut 2013 Oct 15;181:144-50. Epub 2013 Jul 15.

State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academic of Sciences, Guangzhou 510640, China.

A new passive exchange meter (PEM) to measure inter-compartment fluxes of persistent organic pollutants (POPs) at the interface between soil and the atmosphere is described. The PEM uses labeled reference compounds (RC) added in-situ to vegetation litter deployed in open cylinders designed to trap the vertical downward export of the RCs while allowing free exchange of POPs between litter and air. Fluxes of native compounds (bulk deposition, volatilization and downward export) are quantitatively tracked. One scope of the PEM is to investigate the influence of biogeochemical controls on contaminant re-mobilization. The PEM performance was tested in a subtropical forest by comparing measurements under dense canopy and in a canopy gap; conditions in which deposition and turn-over of organic matter (OM) occur at different rates. Significant differences in fate processes were successfully detected. Surprisingly, mobilization by leaching of more hydrophobic compounds was higher under canopy, possibly as a result of canopy mediated enhancement of OM degradation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.envpol.2013.06.020DOI Listing
October 2013
-->