China and America Air/Sea Experiments

人们越来越认识到，大气传输向遥远的大气层、内陆水域、不同区域的沿海水域和公海输送了大量的地球化学痕量物质。在过去10至20年里，人们对痕量物质在大气中的传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散布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已经被各个地区的空气污染物改变了，但共和国中国大气中的气体和颗粒物的组成是独一无二的。这种独特性是来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燃煤和中国紧张的农业发展。自然产生的痕量物质，包括矿物粉尘颗粒，是大气的重要组成部分，现在已知自然发生的物质和人为物质之间的化学反应很重要。由于中国中西部干旱地区矿物颗粒的风沙输送，春季和初夏期间，中国的大气沙尘浓度较高。了解亚洲沙尘的化学、大气输送和大气/海洋交换是一个重要的生物地球化学研究问题。美国和中国合作的大气和海洋科学研究的目标是：(1)表征亚洲气溶胶粒子和雨水的化学成分，并确定矿物气溶胶、微量元素、硝酸盐、磷酸盐和硫酸盐浓度的区域和时间变异性；(2)确定这些物质向沿海水域的大气综合沉积速率；(3)评估中国的人为排放，特别是燃煤产生的排放，对西北太平洋大气和水的化学成分的影响程度；及(4)通过气象分析确定矿物粉尘的可能来源区域。对中国沿海3个采样点和中国黄土高原中部1个采样点的气溶胶粒子样品和大气沉积样品中的Al、As、Br、Ca、Cd、Cl、Co、Cr、Cu、Fe、I、Mn、Na、Pb、Sb、Sc、Se、Sn、Th、V和Zn等元素的含量进行了测定。硫酸盐、硝酸盐和磷酸盐的浓度也将由中国的科学家在一分之一份的样品中测定，并经美国的分析验证。

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.