A grass (Italian rye grass) experiment with complete design of three factors (Hg, grass and exposure) andtwo levels (with and without the factor tested) was carried out in Goteborg, Sweden from May to September,1995, ...A grass (Italian rye grass) experiment with complete design of three factors (Hg, grass and exposure) andtwo levels (with and without the factor tested) was carried out in Goteborg, Sweden from May to September,1995, toward understanding the effect of mercury deposition on plant Hg conteot and its distribution. It hasbeen foulld that besides the two general pathways of Hg absorption, i.e. root uptake and foliar absorption,mercury deposition can also significantly increase Hg content and total load in grass plant. Such effectsseem to be condned only within the above-ground parts of grass plant. Estimate has been made to makeclear of the contributions of different pathways to Hg content and total Hg load in the upper part of grass.Results showed that the coDtribution of Hg deposition accounted for 27%-32% of Hg content in the above-ground parts of grass plant without adding Hg to the soil, decreasing with the increase of soil and/or air Hgconcentrations. The increment of Hg load in the upper part of grass plant caused by Hg deposition duringan interval of two weeks varied between O.o1~O.o7 pg pot-1, contributing to 17%~48% of the total Hg loadin grass plant exposed.展开更多
We performed a comparison analysis of the variations .in Mercury ( Hg) concentrations and the precipitation proxies ( e. g. , 18 O values and 10 Be concentrations) in the Dome C ice core. The results showed that there...We performed a comparison analysis of the variations .in Mercury ( Hg) concentrations and the precipitation proxies ( e. g. , 18 O values and 10 Be concentrations) in the Dome C ice core. The results showed that there were significant correlations between Hg and δ 10O values, 10Be concentrations, indicating that the accumulation rate in Dome C is one of the key factors controlling the variations of Hg concentrations in the past 34 ,000 years, and implying that Hg concentrations in ice core can be used as another reliable proxy of precipitation rate in Antarctica. Based upon the high-resolution δ 18O values, we estimated the variations in mercury deposition flux to Antarctica over the past 34,000 years. The highest mercury deposition flux is about 3. 80 pg cm-2 yr-1 during the Last Glacial Maxium (LGM) as high as 3. 5 times of the mercury deposition flux ( about 1. 08 pg cm -2 yr -1) in Holocene due to the fluctuations in natural mercury emissions such as the oceanic biological emissions.展开更多
Heavy metals,one of the most toxic classes of pollutants,are resistant to degradation and harmful to the biological environment.The lakes that have developed on the Tibetan Plateau are ideal regions to investigate his...Heavy metals,one of the most toxic classes of pollutants,are resistant to degradation and harmful to the biological environment.The lakes that have developed on the Tibetan Plateau are ideal regions to investigate historic heavy metal pollution,particularly through the use of the reliable 210 Pb dating technique.Environmental magnetism has been successfully applied to estimate heavy metal pollution in different environmental systems due to its characteristics of simple processing steps,good sensitivity,and non-destructibility.However,it has not yet been applied to assess heavy metal pollution in lake sediments on the Tibetan Plateau.A series of environmental magnetic investigations of Qiangyong Co Lake sediments(southern Tibetan Plateau) was therefore conducted to explore the relationship between magnetic minerals and mercury(Hg) concentrations.The results showed that the magnetic mineral species in lake sediments remained stable,with similar levels of four different components from 1899 to 2011.However,the proportion of component 1(C1,hematite) increased continuously with the corresponding decrease in the proportion of C2(goethite),while the proportions of C3 and C4(magnetite) did not change significantly.As a result,the bulk magnetic signals(e.g.,SIRM and clf) were unsuitable for the evaluation of the Hg concentration;however,the proportion of hematite had a strong positive correlation with the Hg concentration.It is possible that the Qiangyong Glacier(the main water supply for Qiangyong Co Lake) has experienced faster melting with global and local warming,and the Hg trapped in cryoconite and ice was released.Hematite,with a large specific surface area,has a strong capacity for absorbing Hg,and both materials are ultimately transported to Qiangyong Co Lake.The proportion of hematite in a sample is therefore a suitable semi-quantitative proxy that can be used to evaluate the Hg concentration in Qiangyong Co Lake sediments.This study confirmed that the variation of magnetic minerals can provide a new method to estimate the variation of Hg concentrations and to study the process of Hg deposition in lakes in the southern Tibetan Plateau on the basis of a detailed environmental magnetic analysis.展开更多
Understanding atmospheric mercury(Hg) accumulation in remote montane forests is critical to assess the Hg ecological risk to wildlife and human health. To quantify impacts of vegetation, climatic and topographic facto...Understanding atmospheric mercury(Hg) accumulation in remote montane forests is critical to assess the Hg ecological risk to wildlife and human health. To quantify impacts of vegetation, climatic and topographic factors on Hg accumulation in montane forests, we assessed the Hg distribution and stoichiometric relations among Hg, carbon(C), and nitrogen(N) in four forest types along the elevation of Mt. Gongga. Our results show that Hg concentration in plant tissues follows the descending order of litter > leaf, bark > root > branch > bole wood, indicating the importance of atmospheric Hg uptake by foliage for Hg accumulation in plants. The foliar Hg/C(from 237.0 ± 171.4 to 56.8 ± 27.7 μg/kg) and Hg/N(from 7.5 ± 3.9 to 2.5 ± 1.2 mg/kg) both decrease along the elevation. These elevation gradients are caused by the heterogeneity of vegetation uptake of atmospheric Hg and the variation of atmospheric Hg ° concentrations at different altitudes. Organic soil Hg accumulation is controlled by forest types, topographic and climatic factors, with the highest concentration in the mixed forest(244.9 ± 55.7 μg/kg) and the lowest value in the alpine forest(151.9 ±44.5 μg/kg). Further analysis suggests that soil Hg is positively correlated to C( r^(2) = 0.66) and N( r^(2) = 0.57), and Hg/C and Hg/N both increase with the soil depth. These stoichiometric relations highlight the combined effects from environmental and climatic factors which mediating legacy Hg accumulation and selective Hg absorption during processes of organic soil mineralization.展开更多
The toxic heavy metal mercury(Hg)has significantly enhanced the global Hg cycle influenced by human activities over the last century.In this study,we presented a high-resolution Hg deposition history between∼1780 and...The toxic heavy metal mercury(Hg)has significantly enhanced the global Hg cycle influenced by human activities over the last century.In this study,we presented a high-resolution Hg deposition history between∼1780 and 2015 AD in a sediment core from Xincun Lagoon,located in the southeastern Hainan Island,South China,and analyzed it in conjunction with geochemical elements,grain-size distribution,organic matter,and HYSPLIT backward trajectory simulation.The objective was to investigate the influencing factors affecting historical Hg deposition in relatively remote regions and assess the extent of the effects of natural background and human activities.The results showed that the Hg in the sediment was deposited primarily through atmospheric deposition,which was closely related to regional and even global human activities.Anthropogenic Hg contamination increased gradually from the 1830s to 1850s,possibly due to Hg emissions from Opium Wars I and II occurring in southeastern China.High broad peaks of anthropogenic Hg were observed during the 1910s to 1950s and in the 1980s,likely associated with the two world wars and modern Chinese wars.In addition,a further sharp increase in anthropogenic Hg from the mid-1970s to the present occurred,likely originating from the intense industrial activities in China triggered by the reform and opening-up policy of China in 1978 and some countries in Southeast Asia.展开更多
The gaseous or particulate forms of divalent mercury(HgⅡ) significantly impact the spatial distribution of atmospheric mercury concentration and deposition flux(FLX). In the new nested-grid GEOS-Chem model, we try to...The gaseous or particulate forms of divalent mercury(HgⅡ) significantly impact the spatial distribution of atmospheric mercury concentration and deposition flux(FLX). In the new nested-grid GEOS-Chem model, we try to modify the HgⅡ gas-particle partitioning relationship with synchronous and hourly observations at four sites in China. Observations of gaseous oxidized Hg(GOM), particulate-bound Hg(PBM), and PM 2.5 were used to derive an empirical gas-particle partitioning coefficient as a function of temperature( T) and organic aerosol(OA) concentrations under different relative humidity(RH). Results showed that with increasing RH, the dominant process of HgⅡ gas-particle partitioning changed from physical adsorption to chemical desorption. And the dominant factor of HgⅡ gas-particle partitioning changed from T to OA concentrations. We thus improved the simulated OA concentration field by introducing intermediate-volatility and semi-volatile organic compounds(I/SVOCs) emission inventory into the model framework and refining the volatile distributions of I/SVOCs according to new filed tests in the recent literatures. Finally, normalized mean biases(NMBs) of monthly gaseous element mercury(GEM), GOM, PBM, WFLX were reduced from-33%–29%, 95%–300%, 64%–261%, 117%–122% to-13%–0%,-20%–80%,-31%–50%,-17%–23%. The improved model explains 69%–98% of the observed atmospheric Hg decrease during 2013–2020 and can serve as a useful tool to evaluate the effectiveness of the Minamata Convention on Mercury.展开更多
The potentiostatic deposition of cadmium-rich CMT films onto Ti, Mo, Ni substrates from an aqueous bath was carried out. The photoelectrochemical properties of film electrodes were investigated when used in a solid-li...The potentiostatic deposition of cadmium-rich CMT films onto Ti, Mo, Ni substrates from an aqueous bath was carried out. The photoelectrochemical properties of film electrodes were investigated when used in a solid-liquid junction photoelectrochemical cell (PEC). A.C. capacitance was determined.展开更多
文摘A grass (Italian rye grass) experiment with complete design of three factors (Hg, grass and exposure) andtwo levels (with and without the factor tested) was carried out in Goteborg, Sweden from May to September,1995, toward understanding the effect of mercury deposition on plant Hg conteot and its distribution. It hasbeen foulld that besides the two general pathways of Hg absorption, i.e. root uptake and foliar absorption,mercury deposition can also significantly increase Hg content and total load in grass plant. Such effectsseem to be condned only within the above-ground parts of grass plant. Estimate has been made to makeclear of the contributions of different pathways to Hg content and total Hg load in the upper part of grass.Results showed that the coDtribution of Hg deposition accounted for 27%-32% of Hg content in the above-ground parts of grass plant without adding Hg to the soil, decreasing with the increase of soil and/or air Hgconcentrations. The increment of Hg load in the upper part of grass plant caused by Hg deposition duringan interval of two weeks varied between O.o1~O.o7 pg pot-1, contributing to 17%~48% of the total Hg loadin grass plant exposed.
基金sppoted by the Natinal Natral Sience Founda tion od China(No 407602)The Comoweal Siene Fundation fom Minsay of Science and Technloy(No.20DLA50040-09).
文摘We performed a comparison analysis of the variations .in Mercury ( Hg) concentrations and the precipitation proxies ( e. g. , 18 O values and 10 Be concentrations) in the Dome C ice core. The results showed that there were significant correlations between Hg and δ 10O values, 10Be concentrations, indicating that the accumulation rate in Dome C is one of the key factors controlling the variations of Hg concentrations in the past 34 ,000 years, and implying that Hg concentrations in ice core can be used as another reliable proxy of precipitation rate in Antarctica. Based upon the high-resolution δ 18O values, we estimated the variations in mercury deposition flux to Antarctica over the past 34,000 years. The highest mercury deposition flux is about 3. 80 pg cm-2 yr-1 during the Last Glacial Maxium (LGM) as high as 3. 5 times of the mercury deposition flux ( about 1. 08 pg cm -2 yr -1) in Holocene due to the fluctuations in natural mercury emissions such as the oceanic biological emissions.
基金National Natural Science Foundation of China,No.41506075,No.41430962,No.41574036,No.41705132。
文摘Heavy metals,one of the most toxic classes of pollutants,are resistant to degradation and harmful to the biological environment.The lakes that have developed on the Tibetan Plateau are ideal regions to investigate historic heavy metal pollution,particularly through the use of the reliable 210 Pb dating technique.Environmental magnetism has been successfully applied to estimate heavy metal pollution in different environmental systems due to its characteristics of simple processing steps,good sensitivity,and non-destructibility.However,it has not yet been applied to assess heavy metal pollution in lake sediments on the Tibetan Plateau.A series of environmental magnetic investigations of Qiangyong Co Lake sediments(southern Tibetan Plateau) was therefore conducted to explore the relationship between magnetic minerals and mercury(Hg) concentrations.The results showed that the magnetic mineral species in lake sediments remained stable,with similar levels of four different components from 1899 to 2011.However,the proportion of component 1(C1,hematite) increased continuously with the corresponding decrease in the proportion of C2(goethite),while the proportions of C3 and C4(magnetite) did not change significantly.As a result,the bulk magnetic signals(e.g.,SIRM and clf) were unsuitable for the evaluation of the Hg concentration;however,the proportion of hematite had a strong positive correlation with the Hg concentration.It is possible that the Qiangyong Glacier(the main water supply for Qiangyong Co Lake) has experienced faster melting with global and local warming,and the Hg trapped in cryoconite and ice was released.Hematite,with a large specific surface area,has a strong capacity for absorbing Hg,and both materials are ultimately transported to Qiangyong Co Lake.The proportion of hematite in a sample is therefore a suitable semi-quantitative proxy that can be used to evaluate the Hg concentration in Qiangyong Co Lake sediments.This study confirmed that the variation of magnetic minerals can provide a new method to estimate the variation of Hg concentrations and to study the process of Hg deposition in lakes in the southern Tibetan Plateau on the basis of a detailed environmental magnetic analysis.
基金funded by the National Natural Science Foundation of China (Nos. 41977272 and 42007307)。
文摘Understanding atmospheric mercury(Hg) accumulation in remote montane forests is critical to assess the Hg ecological risk to wildlife and human health. To quantify impacts of vegetation, climatic and topographic factors on Hg accumulation in montane forests, we assessed the Hg distribution and stoichiometric relations among Hg, carbon(C), and nitrogen(N) in four forest types along the elevation of Mt. Gongga. Our results show that Hg concentration in plant tissues follows the descending order of litter > leaf, bark > root > branch > bole wood, indicating the importance of atmospheric Hg uptake by foliage for Hg accumulation in plants. The foliar Hg/C(from 237.0 ± 171.4 to 56.8 ± 27.7 μg/kg) and Hg/N(from 7.5 ± 3.9 to 2.5 ± 1.2 mg/kg) both decrease along the elevation. These elevation gradients are caused by the heterogeneity of vegetation uptake of atmospheric Hg and the variation of atmospheric Hg ° concentrations at different altitudes. Organic soil Hg accumulation is controlled by forest types, topographic and climatic factors, with the highest concentration in the mixed forest(244.9 ± 55.7 μg/kg) and the lowest value in the alpine forest(151.9 ±44.5 μg/kg). Further analysis suggests that soil Hg is positively correlated to C( r^(2) = 0.66) and N( r^(2) = 0.57), and Hg/C and Hg/N both increase with the soil depth. These stoichiometric relations highlight the combined effects from environmental and climatic factors which mediating legacy Hg accumulation and selective Hg absorption during processes of organic soil mineralization.
基金Under the auspices of the National Natural Science Foundation of China(No.42071108,41671194)。
文摘The toxic heavy metal mercury(Hg)has significantly enhanced the global Hg cycle influenced by human activities over the last century.In this study,we presented a high-resolution Hg deposition history between∼1780 and 2015 AD in a sediment core from Xincun Lagoon,located in the southeastern Hainan Island,South China,and analyzed it in conjunction with geochemical elements,grain-size distribution,organic matter,and HYSPLIT backward trajectory simulation.The objective was to investigate the influencing factors affecting historical Hg deposition in relatively remote regions and assess the extent of the effects of natural background and human activities.The results showed that the Hg in the sediment was deposited primarily through atmospheric deposition,which was closely related to regional and even global human activities.Anthropogenic Hg contamination increased gradually from the 1830s to 1850s,possibly due to Hg emissions from Opium Wars I and II occurring in southeastern China.High broad peaks of anthropogenic Hg were observed during the 1910s to 1950s and in the 1980s,likely associated with the two world wars and modern Chinese wars.In addition,a further sharp increase in anthropogenic Hg from the mid-1970s to the present occurred,likely originating from the intense industrial activities in China triggered by the reform and opening-up policy of China in 1978 and some countries in Southeast Asia.
基金supported by the National Natural Science Foundation of China (No. 21625701 )the Major State Basic Research Development Program of China ( 973 ) (No. 2013CB430001 )+1 种基金the Youth Project of National Natural Science Foundation of China (No. 21607090 )the Shuimu Tsinghua Scholar Program (No. 2021SM017)。
文摘The gaseous or particulate forms of divalent mercury(HgⅡ) significantly impact the spatial distribution of atmospheric mercury concentration and deposition flux(FLX). In the new nested-grid GEOS-Chem model, we try to modify the HgⅡ gas-particle partitioning relationship with synchronous and hourly observations at four sites in China. Observations of gaseous oxidized Hg(GOM), particulate-bound Hg(PBM), and PM 2.5 were used to derive an empirical gas-particle partitioning coefficient as a function of temperature( T) and organic aerosol(OA) concentrations under different relative humidity(RH). Results showed that with increasing RH, the dominant process of HgⅡ gas-particle partitioning changed from physical adsorption to chemical desorption. And the dominant factor of HgⅡ gas-particle partitioning changed from T to OA concentrations. We thus improved the simulated OA concentration field by introducing intermediate-volatility and semi-volatile organic compounds(I/SVOCs) emission inventory into the model framework and refining the volatile distributions of I/SVOCs according to new filed tests in the recent literatures. Finally, normalized mean biases(NMBs) of monthly gaseous element mercury(GEM), GOM, PBM, WFLX were reduced from-33%–29%, 95%–300%, 64%–261%, 117%–122% to-13%–0%,-20%–80%,-31%–50%,-17%–23%. The improved model explains 69%–98% of the observed atmospheric Hg decrease during 2013–2020 and can serve as a useful tool to evaluate the effectiveness of the Minamata Convention on Mercury.
文摘The potentiostatic deposition of cadmium-rich CMT films onto Ti, Mo, Ni substrates from an aqueous bath was carried out. The photoelectrochemical properties of film electrodes were investigated when used in a solid-liquid junction photoelectrochemical cell (PEC). A.C. capacitance was determined.
