Effects of Point Source Loadings, Sub-basin Inputs and Longitudinal Variation in Material Retention on C, N and P Delivery from the Ohio River Basin
Effects of Point Source Loadings, Sub-basin Inputs and Longitudinal Variation in Material Retention on C, N and P Delivery from the Ohio River Basin
复制标题
DOI：
10.1007/s10021-005-0044-3
复制
发表时间：
2005-10
期刊：
影响因子：
3.7
通讯作者：
P. Bukaveckas;D. Guelda;Jeffrey D. Jack;R. Koch;Tim Sellers;J. Shostell
中科院分区：
文献类型：
--
作者：
P. Bukaveckas;D. Guelda;Jeffrey D. Jack;R. Koch;Tim Sellers;J. Shostell
大流域内物质通量的空间变异性可能源于点源输入、子流域的不同贡献以及物质转化和滞留的纵向变化。通过测量整个俄亥俄河流域的瞬时通量，我们能够推断这些因素在决定C、N和P从该流域的总体出口中的重要性。我们的研究跨越了俄亥俄河下游645公里的范围，包括在俄亥俄河与密西西比河汇合处贡献了至少1%俄亥俄河流量的所有支流。精耕细作的北部次流域(沃巴什河)为进入俄亥俄河的氮和磷贡献了很大一部分。在南部次流域(田纳西河和坎伯兰河)，蓄水和不那么密集的耕作似乎减少和推迟了物质输送，特别是在N。南部河流在低流量条件下占进入密西西比河的水的比例较大，这一比例在过去50年中有所增加。研究河段的上游部分被发现是Chla和DOC的净来源和无机N的净汇，这表明该部分河流为自养生产提供了总体上有利的环境。NH4的点源负荷是上游河段的重要输入，但在溶解无机氮的总体预算中所占的比例相对较小。
Spatial variability in material fluxes within large river basins may arise from point source inputs, variable contributions from sub-basins and longitudinal variation in material transformation and retention. By measuring instantaneous fluxes throughout the Ohio River basin, we were able to draw inferences about the importance of these factors in determining the overall export of C, N and P from the basin. Our study spanned the lower 645 km of the Ohio River and included all tributaries that contributed at least 1% of the volume of the Ohio River at its confluence with the Mississippi. The intensively cultivated northern sub-basin (Wabash River) contributed a large fraction of N and P entering the Ohio River. In the southern sub-basins (Tennessee and Cumberland Rivers), impoundments and less intense cultivation appear to diminish and delay material delivery particularly with respect to N. The southern rivers account for a proportionately larger fraction of the water entering the Mississippi River during low discharge conditions and this fraction has increased during the past 50 years. The upper portion of the study reach was found to be a net source of CHLa and DOC and a net sink for inorganic N suggesting that this portion of the river provided a generally favorable environment for autotrophic production. Point source loadings of NH4were significant inputs to the upper sub-reach but a relatively small component of the overall budget for dissolved inorganic N.