Quantification of seasonal sediment and phosphorus transport dynamics in an agricultural watershed using radiometric fingerprinting techniques

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• 作者：Natalie L. H. Huisman (1)
  K. G. Karthikeyan (2)
  Jasmeet Lamba (2)
  Anita M. Thompson (2)
  Graham Peaslee (3)
  
• 关键词：Fallout radionuclides ; Phosphorus ; Sediment fingerprinting ; Sediment sources
• 刊名：Journal of Soils and Sediments
• 出版年：2013
• 出版时间：December 2013
• 年：2013
• 卷：13
• 期：10
• 页码：1724-1734
• 全文大小：
• 作者单位：Natalie L. H. Huisman (1)
  K. G. Karthikeyan (2)
  Jasmeet Lamba (2)
  Anita M. Thompson (2)
  Graham Peaslee (3)
  
  1. Department of Chemistry, Union College, Schenectady, NY, 12308, USA
  2. Department of Biological Systems Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
  3. Department of Chemistry, Hope College, Holland, MI, 49422, USA
  
• ISSN：1614-7480

文摘

Purpose Phosphorus (P) is a limiting nutrient for most US Midwestern aquatic systems and, therefore, increases of P, through point or non-point sources (NPS) of pollution such as agriculture, causes eutrophication. Identifying specific NPS contributions (e.g., upland vs. stream channels) for sediments and P is difficult due to the distributed nature of the pollution. Therefore, studies which link the spatial and temporal aspects of sediment and P transport in these systems can help better characterize the extent of NPS pollution. Materials and methods Our study used fingerprinting techniques to determine sources of sediments in an agricultural watershed (the North Fork of the Pheasant Branch watershed; 12.4km2 area) in Wisconsin, USA, during the spring, summer, and fall seasons of 2009. The primary sources considered were uplands (cultivated fields), stream bank, and streambed. The model used fallout radionuclides, 137Cs, and 210Pbxs, along with total P to determine primary sediment sources. A shorter-lived fallout radioisotope, 7Be, was used to determine the sediment age and percent new sediments in streambed and suspended sediment samples (via the 7Be/210Pbxs ratio). Results and discussion Upland areas were the primary source of suspended sediments in the stream channels followed by stream banks. The sediment age and percent new sediment for the streambed and suspended sediments showed that the channel contained and transported newer (or more recently tagged with 7Be) sediments in the spring season (931days sediment age), while relatively old sediments (16518days) were moving through the channel system during the fall season. Conclusions Upland areas are the major contributors to in-stream suspended sediments in this watershed. Sediment resuspension in stream channels could play an important role during the later part of the year. Best management practices should be targeted in the upland areas to reduce the export of sediments and sediment-bound P from agricultural watersheds.