Future climate change decreases multi-pathway but increases respiratory human health risks of PAHs across China

Future climate change will affect the environmental fate of hydrophobic organic contaminants(HOCs)and associated human health risks,yet the extent of these effects remains unknown.Here,we couple a high-resolution environmental multimedia model with a bioaccumulation model to study the multimedia distribution of 16 priority polycyclic aromatic hydrocarbons(PAHs),a group of HOCs,and assess future PAH-related human health risks under varying climate change scenarios over China at a continental scale.After removing the effects of PAH emission changes,we find that the total PAH concentrations would decrease in the air,freshwater,sediment,soil,and organisms,while the high-molecular-weight PAH would increase in the air with climate warming from 1.5°C to 4°C.Consequently,the multi-pathway exposure human health risks predominately influenced by dietary ingestion are expected to decrease by 1.7%–20.5%,while the respiratory risks are projected to rise by 0.2%–5.8%in the future.However,the persistently high multi-pathway human health risks underscore the need for reducing future PAH emissions by 69%compared with 2009 levels in China.Our study demonstrates the urgency of limiting PAH emissions under future climate change for public health and highlights the importance of including the contribution of dietary ingestion in human health risk assessment.

Modeling historical budget for β-Hexachlorocyclohexane(HCH)in the Arctic Ocean:A contrast to α-HCH

The historical annual loading to,removal from,and cumulative burden in the Arctic Ocean for β-hexachlorocyclohexane(β-HCH),an isomer comprising 5e12%of technical HCH,is investigated using a mass balance box model from 1945 to 2020.Over the 76 years,loading occurred predominantly through ocean currents and river inflow(83%)and only a small portion via atmospheric transport(16%).β-HCH started to accumulate in the Arctic Ocean in the late 1940s,reached a peak of 810 t in 1986,and decreased to 87 t in 2020,when its concentrations in the Arctic water and air were~30 ng m^(-3)and~0.02 pg m^(-3),respectively.Even though β-HCH and α-HCH(60e70%of technical HCH)are both the isomers of HCHs with almost identical temporal and spatial emission patterns,these two chemicals have shown different major pathways entering the Arctic.Different from α-HCH with the long-range atmospheric transport(LRAT)as its major transport pathway,β-HCH reached the Arctic mainly through long-range oceanic transport(LROT).The much higher tendency of β-HCH to partition into the water,mainly due to its much lower Henry's Law Constant than α-HCH,produced an exceptionally strong pathway divergence with β-HCH favoring slow transport in water and α-HCH favoring rapid transport in air.The concentration and burden of β-HCH in the Arctic Ocean are also predicted for the year 2050 when only 4.4-5.3 t will remain in the Arctic Ocean under the influence of climate change.

Sources and environmental fate of pyrogenic polycyclic aromatic hydrocarbons(PAHs)in the Arctic

Polycyclic aromatic hydrocarbons(PAHs)are large class of hydrophobic,semi-volatile organic contaminants that may enter the environment from both natural sources and anthropogenic activities.Pyrogenic PAHs arise from the incomplete combustion of fossil fuels and organic matter and following dispersal via long-range transport and may subsequently deposit in surface waters,soils and sediments of remote regions,including the Arctic.The current review summarizes and discusses Arctic data that is available for combustion-derived PAHs between 2004 and early 2018,focusing largely on data collected from remote,unexploited Arctic regions and from studies that provide some evidence of a pyrogenic origin.The increasing use of attribution ratios,which aid in discriminating PAHs from petrogenic or pyrogenic sources,suggest PAHs found in Arctic marine waters and sediment predominantly originate from natural underwater seeps,while those measured in air,freshwater,and terrestrial environments are likely to have originated from atmospheric and combustion-derived sources.Modeling efforts indicate that atmospheric PAHs in the Canadian and Norwegian Arctic are likely to have originated in the northern hemisphere e predominantly from Western Russia,northern Europe,and North America.East Asia appears to be a minor source of PAHs to the Arctic,despite contributing more than 50%of global PAH emissions.In comparison to the growing data for atmospheric PAHs,environmental data for these compounds in terrestrial and freshwater environments remain scarce.PAHs have been detected in Arctic biota from terrestrial,freshwater and marine environments,indicating exposure,however,levels are generally low,as most organisms efficiently metabolize parent PAHs.Globally,PAH emissions are expected to decline in the future,however models suggest the Arctic may not experience the same magnitude of decline projected for other world regions.Furthermore,future changes in climate may contribute to a re-volatilization of environmental PAHs,providing a source of secondary emissions to the Arctic atmosphere,emphasizing the importance of future monitoring for understanding the sources,fate and impacts of PAHs in the Arctic.

Hexachlorobutadiene(HCBD)contamination in the Arctic environment:A review

Hexachlorobutadiene(HCBD)is a halogenated hydrocarbon that is primarily produced as an unintentional byproduct in the manufacture of chlorinated solvents.Similarities between HCBD and other persistent organic pollutants(POPs)led to its listing in 2015 for global regulation under the Stockholm Convention on POPs.HCBD's toxicity and propensity for long-range transport means there is special concern for its potential impacts on Arctic ecosystems.The present review comprehensively summarizes all available information of the occurrence of HCBD in the Arctic environment,including its atmospheric,terrestrial,freshwater and marine ecosystems and biota.Overall,reports of HCBD in Arctic environmental media are scarce.HCBD has been measured in Arctic air collected from monitoring stations in Finland and Canada,yet there is a dearth of data for other abiotic matrices(i.e.soils,sediments,glacier ice,freshwaters and seawater).Low HCBD concentrations have been measured in Arctic terrestrial and marine biota,which is consistent with laboratory studies that indicate that HCBD has the potential to bioaccumulate,but not to biomagnify.Available data for Arctic biota suggest that terrestrial birds and mammals and seabirds,have comparatively higher HCBD concentrations than fish and marine mammals,warranting additional research.Although spatial and temporal trends in HCBD concentrations in the Arctic are currently limited,future monitoring of HCBD in the Arctic will be important for assessing the impact of global regulations newly-imposed by the Stockholm Convention on POPs.

Levels and trends of current-use pesticides(CUPs)in the arctic:An updated review,2010-2018

Global regulations and many regional and national controls restrict the use of substances that exhibit the potential for environmental persistence and long-range transport.Nevertheless,many current-use pesticides(CUPs)continue to be newly discovered in remote regions,including the Arctic.The present review serves as an update,summarizing newly available information for CUPs in the Arctic environment and biota published from 2010 to 2018.Since 2010,at least seven new CUPs have been measured in Arctic media:2-methyl-4-chlorophenoxyacetic acid(MCPA),metribuzin,pendimethalin,phosalone,quizalofop-ethyl,tefluthrin and triallate.Considering the large number of pesticides in current use,the number measured in the Arctic is very limited,however,modelling studies have identified additional CUPs as potential Arctic contaminants that have yet to be investigated in the Arctic.Owing to their recent detection,reports of CUPs in the Arctic are limited,but growing.CUPs have been reported in a wide range of abiotic Arctic matrices,including air,snow,ice,freshwater and seawater,indicating their capacity for long-range atmospheric transport,however,concentrations are generally low in comparison to legacy pesticides and other persistent organic pollutants(POPs).Recent food-web studies indicate CUPs can enter Arctic terrestrial and marine food chains,however,in contrast to POPs,the highest concentrations of many CUPs were found in lower trophic-level organisms,and the lowest concentrations detected in animals at the highest trophic levels(i.e,ringed seals,polar bear,caribou,and wolves)indicating significant trophic dilution.The detection of CUPs in the remote Arctic ecosystem reinforces the need for continued monitoring of both known and potential Arctic pollutants to prevent impacts on human and environmental health as the global arsenal of pesticides used in agriculture continuously changes.

Chemicals of Emerging Arctic Concern:Preface

1.Preface The Arctic Monitoring and Assessment Programme(AMAP)was established as an international program for monitoring and assessing Arctic pollution in 1991,under the Arctic Environmental Protection Strategy[1].AMAP is now aWorking Group of the Arctic Council(http://www.arctic-council.org)responsible for monitoring and assessing a range of pollution-and climate change-related issues in the Arctic in order to“provide reliable and sufficient information on the status of,and threats to,the Arctic environment,and scientific advice on actions to be taken in order to support Arctic governments in their efforts to take remedial and preventive actions relating to contaminants and adverse effects of climate change”(see Ref.[2]).