First of all, I wish to thank the Advances in Atmospheric Sciences (AAS) Editorial Board for recommending the publication of this original letter, summarizing my personal perspective on the reform of AAS, that was dis...First of all, I wish to thank the Advances in Atmospheric Sciences (AAS) Editorial Board for recommending the publication of this original letter, summarizing my personal perspective on the reform of AAS, that was distributed during its 19 December 2001 Board meeting. The letter has now been significantly improved by the incorporation of many helpful comments and suggestions from extensive email discussions conducted among over 60 foreign participants, including several board members of AAS, as well as from numerous personal communications (see the acknowledgements section).展开更多
Mercury (Hg) is a neurotoxin to humans and wildlife that has a quantitatively important gas phase that makes its atmospheric cycle an important part of exposure pathways to these organisms. The important atmospheric ...Mercury (Hg) is a neurotoxin to humans and wildlife that has a quantitatively important gas phase that makes its atmospheric cycle an important part of exposure pathways to these organisms. The important atmospheric forms are elemental Hg (Hg(0)), inorganic gas phase Hg (HgH gs ), and inorganic particulate Hg(HgIIp). Each form has different behavior depending on its chemical and physical properties. Generally, scientists have found with trace metal clean sampling and analytical techniques, that background Hg levels are 1—2 ng/m\+3 in air, 0.1—2 ng/L in surface waters, 5—25 ng/L in rainwater, and less than 0.1 μg/g in sediments remote from natural Hg minerals and wastewater sources. Values in excess of these concentrations generally indicate local anthropogenic influences or contaminated samples. Broad scale estimates of Hg inputs to the atmosphere suggest that annual anthropogenic fluxes to the atmosphere as Hg(0) are about 40 percent of the total global cycle, oceanic evasion is about 40 percent, and (by difference) the remaining input to the global cycle (20 percent) is evasion from terrestrial sources, largely via soils and vegetation. This paper summarizes recent data that will constrain estimates from these sources. For example, terrestrial sources could approach 40 percent and annual anthropogenic inputs be correspondingly less. Furthermore, a historic perspective is needed because Hg has cycled atmospherically over geologic time. In addition to the uncertainty in source quantification, methylation must be a focus of risk analysis, because this process is responsible for risks to human and ecosystem health for almost all modern day Hg exposures.展开更多
基金Acknowledgements. I am very thankful to many of my overseas colleagues and the foreign Board members of AAS for their interests and active email discussions on the improvement of this report. In particular, I am very in-debted to Drs. Ferd Baer, Ming Cai
文摘First of all, I wish to thank the Advances in Atmospheric Sciences (AAS) Editorial Board for recommending the publication of this original letter, summarizing my personal perspective on the reform of AAS, that was distributed during its 19 December 2001 Board meeting. The letter has now been significantly improved by the incorporation of many helpful comments and suggestions from extensive email discussions conducted among over 60 foreign participants, including several board members of AAS, as well as from numerous personal communications (see the acknowledgements section).
文摘Mercury (Hg) is a neurotoxin to humans and wildlife that has a quantitatively important gas phase that makes its atmospheric cycle an important part of exposure pathways to these organisms. The important atmospheric forms are elemental Hg (Hg(0)), inorganic gas phase Hg (HgH gs ), and inorganic particulate Hg(HgIIp). Each form has different behavior depending on its chemical and physical properties. Generally, scientists have found with trace metal clean sampling and analytical techniques, that background Hg levels are 1—2 ng/m\+3 in air, 0.1—2 ng/L in surface waters, 5—25 ng/L in rainwater, and less than 0.1 μg/g in sediments remote from natural Hg minerals and wastewater sources. Values in excess of these concentrations generally indicate local anthropogenic influences or contaminated samples. Broad scale estimates of Hg inputs to the atmosphere suggest that annual anthropogenic fluxes to the atmosphere as Hg(0) are about 40 percent of the total global cycle, oceanic evasion is about 40 percent, and (by difference) the remaining input to the global cycle (20 percent) is evasion from terrestrial sources, largely via soils and vegetation. This paper summarizes recent data that will constrain estimates from these sources. For example, terrestrial sources could approach 40 percent and annual anthropogenic inputs be correspondingly less. Furthermore, a historic perspective is needed because Hg has cycled atmospherically over geologic time. In addition to the uncertainty in source quantification, methylation must be a focus of risk analysis, because this process is responsible for risks to human and ecosystem health for almost all modern day Hg exposures.
