Internal Phosphorus Storage in Two Headwater Agricultural Streams in the Lake Erie Basin
Internal Phosphorus Storage in Two Headwater Agricultural Streams in the Lake Erie Basin
复制标题
伊利湖流域两条源头农业溪流磷的内部储量
DOI：
10.1021/acs.est.9b04232
复制
发表时间：
2020-01-07
影响因子：
11.4
通讯作者：
Covault, Alexandra J.
中科院分区：
文献类型：
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作者：
Casillas-Ituarte, Nadia N.;Sawyer, Audrey H.;Covault, Alexandra J.
沉积物中的内磷(P)在湖泊营养动态中起着重要作用，有时在外部负荷减少后很长一段时间内才发生。同样，尽管最佳管理措施旨在减少来自相邻田地的外部磷负荷，但内部磷来源可能会驱动流向较大河流和湖泊的小型农业溪流的营养动态。在这里，用顺序提取的方法对春季和夏季从伊利湖流域的两条农业小溪采集的岩芯进行了内部磷浓度的测量，伊利湖是一个正在经历SRP负荷增加的大型富营养化湖泊。春季和夏季的平均总可提取磷浓度在5%以内，但可移动的磷结合部分在夏季几乎翻了一番，这可能是由于亚缺氧、停滞的表层水体下有机质矿化或铁还原的加速所致。有一个站点的内部磷浓度长期高于25%-75%，尽管实施了最佳管理实践，如草地缓冲。在这两个季节，该地点也有更多的限制水流的水生植被，地表水中的溶解氧较少，沉积物中的有机质较多，这表明水文、沉积物成分和植被的变化影响了整个农业小溪中磷的滞留热点。
Internal phosphorus (P) in sediments plays an important role in the nutrient dynamics of lakes, sometimes long after external loads have been reduced. Similarly, internal P sources may drive the nutrient dynamics of small agricultural streams that drain to larger rivers and lakes, despite best management practices intended to reduce external P loads from adjacent fields. Here, internal P concentrations were measured with sequential extraction on cores collected in spring and summer from two small agricultural streams in the drainage basin of Lake Erie, a large, eutrophic lake experiencing increasing SRP loads. Average total extractable P concentrations were similar to within 5% during spring and summer, but mobile P binding fractions nearly doubled in summer, possibly due to accelerated rates of organic matter mineralization or iron reduction beneath suboxic, stagnant surface waters. One site had chronically greater internal P concentrations by 25-75%, despite the implementation of best management practices such as grass buffers. The site also had more aquatic vegetation that restricted the flow, less dissolved oxygen in surface water, and greater organic matter in sediments during both seasons, suggesting that variations in hydrology, sediment composition, and vegetation influence hot spots of P retention throughout small agricultural streams.