China and America Air/Sea Experiments

人们日益认识到，大气运输从地球化学角度将大量微量物质输送到遥远的大气和内陆水域、各区域的沿海水域以及公海。在过去的10至20年中，人们对微量物质的大气运输和沉积的兴趣显著增加，部分原因是这一途径现在被认为是在整个环境中分散化学污染物的重要手段。事实上，各种微量物质的自然生物地球化学循环在各个地区都受到空气污染物的改变，但中华人民共和国大气中气体和颗粒的组成是独特的。这种独特性是源自人为来源和自然来源的材料的结果。中国大气污染物的主要来源是煤炭的燃烧和中国农业的密集发展。自然产生的微量物质，包括矿物粉尘颗粒，是大气的重要组成部分，现在已知自然产生的和人为产生的物质之间的化学反应是重要的。由于中国中西部干旱地区矿物颗粒的风成运输，中国在春夏初出现了高浓度的大气沙尘。了解亚洲沙尘的化学、大气输送和海气交换是生物地球化学研究的一个重要课题。中美大气和海洋科学合作研究的目标是：(1)表征亚洲气溶胶颗粒和雨水的化学成分，确定矿物气溶胶、微量元素、硝酸盐、磷酸盐和硫酸盐浓度的区域和时间变化；(2)确定这些物质向沿海水域的综合大气沉降速率；(3)评估中国的人为排放，特别是燃煤排放对北太平洋西部大气和水体化学的影响程度；(4)通过气象分析确定矿尘可能的源区。本文将在中华人民共和国沿海的三个地点和中国中部黄土高原的一个地点测定来自近对流层的气溶胶颗粒样品和大气沉积样品中选定的微量元素（Al、As、Br、Ca、Cd、Cl、Co、Cr、Cu、Fe、I、Mn、Na、Pb、Sb、Sc、Se、Sn、Th、V和Zn）的浓度。硫酸盐、硝酸盐和磷酸盐的浓度也将由中国科学家在等分样品中测定，并由美国的分析进行验证

There is growing awareness that atmospheric transport delivers geochemically significant quantities of trace substances to the remote atmosphere and to inland waters, coastal waters of various regions and the open ocean. Interest in the atmospheric transport and deposition of trace substances has increased significantly in the past 10 to 20 years in part because this pathway is now recognized as an important means for dispersing chemical contaminants throughout the environment. The natural biogeochemical cycles of a variety of trace substances have, in fact, been altered by air pollutants in various regions, but the composition of gases and particles in the atmosphere of the People's Republic of China is unique. This uniqueness is a result of material derived from anthropogenic sources as well as those from naturally occurring sources. The major source of air pollutants in China is the combustion of coal and intense agricultural development in China. Naturally occurring trace substances, including mineral dust particles, are important components of the atmosphere, and chemical reactions between naturally occurring and anthropogenic materials are now known to be important. High concentrations of atmospheric dust occur in China during the spring and early summer due to the eolian transport of mineral particles from arid regions in central and western China. Understanding the chemistry, atmospheric transport, and air/sea exchange of Asia dust is an important biogeochemical research issue. The objectives for the cooperative atmospheric and ocean science studies between the U.S. and China are: (1) to characterize the chemical composition of aerosol particles and rainwater from Asian and determine the areal and temporal variability in the concentrations of mineral aerosol, trace elements, nitrate, phosphate, and sulfate; (2) to determine the integrated atmospheric deposition rates of these substances to coastal waters; (3) to evaluate the extent to which anthropogenic emissions from China, particularly those that result from the combustion of coal, affect the chemistry of the atmosphere and waters of the western North Pacific; and (4) to identify probable source areas for mineral dust through meteorological analyses. The concentrations of selected trace elements (Al, As, Br, Ca, Cd, Cl, Co, Cr, Cu, Fe, I, Mn, Na, Pb, Sb, Sc, Se, Sn, Th, V, and Zn) will be determined in aerosol particle samples and atmospheric deposition samples from the near surface troposphere at three sites along the coast of the People's Republic of China (PRC) and at one site in the Central Loess Plateau in China. The concentrations of sulfate, nitrate, and phosphate also will be determined in aliquots of the samples by scientists from China and verified by analyses in the U.S.