Increasing eolian dust deposition in the western United States linked to human activity
Increasing eolian dust deposition in the western United States linked to human activity
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DOI：
10.1038/ngeo133
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发表时间：
2008-03-01
影响因子：
18.3
通讯作者：
Reynolds, R. L.
中科院分区：
文献类型：
--
作者：
Neff, J. C.;Ballantyne, A. P.;Reynolds, R. L.
来自沙尘的矿物气溶胶对气候以及海洋和陆地生物地球化学循环具有重要影响。这些气溶胶是由地表土壤的风蚀产生的。因此，沙尘排放的数量会受到改变地表沉积物的人类活动的影响。然而，在过去两个世纪人类人口和聚居地迅速扩张之后，区域和全球尺度的沙尘通量变化尚未得到很好的理解。在这里，我们测定了美国西部内陆地区过去5000年高山湖泊沉积物的沉积速率和地球化学性质。我们发现，在19世纪美国西部定居点增加之后，沙尘负荷水平比全新世晚期平均值增加了500%。我们认为，沙尘沉积增加是由20世纪初牲畜放牧的扩张引起的。较大的沙尘通量一直持续到21世纪初，导致高山生态系统中钾、镁、钙、氮和磷的输入增加了五倍多，这对地表水碱度、水生生产力和陆地养分循环都有影响。
Mineral aerosols from dust are an important influence on climate and on marine and terrestrial biogeochemical cycles. These aerosols are generated from wind erosion of surface soils. The amount of dust emission can therefore be affected by human activities that alter surface sediments. However, changes in regional- and global-scale dust fluxes following the rapid expansion of human populations and settlements over the past two centuries are not well understood. Here we determine the accumulation rates and geochemical properties of alpine lake sediments from the western interior United States for the past 5,000 years. We find that dust load levels increased by 500% above the late Holocene average following the increased western settlement of the United States during the nineteenth century. We suggest that the increased dust deposition is caused by the expansion of livestock grazing in the early twentieth century. The larger dust flux, which persists into the early twenty-first century, results in a more than fivefold increase in inputs of K, Mg, Ca, N and P to the alpine ecosystems, with implications for surface-water alkalinity, aquatic productivity and terrestrial nutrient cycling.