Effect of freshets on the flux of groundwater nitrate through streambed sediments
Effect of freshets on the flux of groundwater nitrate through streambed sediments
复制标题
淡水对地下水硝酸盐通过河床沉积物通量的影响
DOI：
10.1029/2007wr006488
复制
发表时间：
2008
影响因子：
5.4
通讯作者：
A. Mills
中科院分区：
文献类型：
--
作者：
Chuanhui Gu;G. Hornberger;J. Herman;A. Mills
洪水波通过桑迪河流沉积物时，可导致地下水向河流的排放发生变化，其范围从排放速率的瞬时降低到水流的逆转以及河流沉积物中河流水的临时储存。这些现象在具有完整岩芯的实验室研究中进行了检查，并通过数值建模来评估物理和生物过程对从受硝酸盐污染的地下水到溪流的硝酸盐通量的影响。通过富含有机物的沉积物的地下水流量与反硝化作用之间的平衡最终决定了硝酸盐向河流的流出。数值模型的结果表明，高洪水水位和低沉积物水力扩散率可能导致暴雨事件后地表水的过量硝酸盐负荷，而大沉积物水力扩散率，无论水流水位变化的大小如何，通过允许水在地下的更长停留时间，通过反硝化促进更大的NO3−去除。
The passage of a flood wave over sandy stream sediments can cause changes in the discharge of groundwater to the stream that range from a transient reduction in the discharge rate to a reversal of flow and temporary storage of stream water in the stream sediments. These phenomena were examined in laboratory studies with an intact core and by numerical modeling to assess the effect of both physical and biological processes on the nitrate flux from nitrate‐contaminated groundwater to a stream. The balance between the rates of groundwater flow through organic‐rich sediments and of denitrification ultimately determines the efflux of nitrate to the stream. The transient impact on nitrate loading suggested by results from the numerical model indicates that high flood stage and low‐sediment hydraulic diffusivity can result in excess nitrate loading to surface water following storm events, whereas large‐sediment hydraulic diffusivity, regardless of the size of stream stage changes, facilitates greater removal of NO3− by denitrification by allowing for a longer residence time of water in the subsurface.