Beaver dams along an agricultural stream in southern Ontario, Canada: their impact on riparian zone hydrology and nitrogen chemistry
Beaver dams along an agricultural stream in southern Ontario, Canada: their impact on riparian zone hydrology and nitrogen chemistry
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DOI：
10.1002/hyp.7249
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发表时间：
2009-04-30
影响因子：
3.2
通讯作者：
Duval, Tim P.
中科院分区：
文献类型：
--
作者：
Hill, Alan R.;Duval, Tim P.
比较了加拿大安大略南部一条农业河流在建造河狸坝沿着前后河岸带的水文和氮素地球化学特征。河狸织补增加了表面洪水，并通过LIP将河岸地下水位提高到1.0 m。增加水力梯度内陆从流限制进入富氧硝酸盐的地下水从邻近的农田。渗透性河岸沉积物覆盖密集直到保持饱和在夏季和秋季的几个月，而大坝建设之前，大面积的河岸带是不饱和的，在这些季节，每年。比弗坝的建设产生了显着的变化，河岸地下水化学。中位溶解氧浓度较低的河岸地下水大坝建设后（0.9-2.1毫克L-1）比在大坝前的时期（2.3-3.9毫克L-1）。秋季和春季NO3-N浓度中位数也低于母鼠后期（0.03-0.07 mg L-1）与母鼠前期（0.1-0.3 mg L-1）。与此相反，在秋季和春季的中位数NH 4-N浓度较高的大坝建设后（0.3-0.4毫克L-1）比建设前（0.13-0.14毫克L-1）。结果表明，河狸坝可以增加流入河岸区，限制地下水位下降，并增加饱和河岸土壤的深度，变得更加厌氧，这些地下水文和化学的变化有可能影响运输和转化的硝酸盐通量从邻近农田的农业景观。版权所有（C）2009约翰威利父子有限公司
The hydrology and nitrogen biogeochemistry of a riparian zone were compared before and after the construction of beaver dams along an agricultural stream in southern Ontario, Canada. The beaver darns increased surface flooding and raised the riparian water table by LIP to 1.0 m. Increased hydraulic gradients inland from the stream limited the entry of oxic nitrate-rich subsurface water from adjacent cropland. Permeable riparian sediments overlying dense till remained saturated during the summer and autumn months, whereas before dam construction a large area of the riparian zone was unsaturated in these seasons each year. Beaver dam construction produced significant changes in riparian groundwater chemistry. Median dissolved oxygen concentrations were lower in riparian groundwater after dam construction (0.9-2.1 mg L-1) than in the pre-dam period (2.3-3.9 mg L-1). Median NO3-N concentrations in autumn and spring were also lower in the post-dam (0.03-0.07 mg L-1) versus the pre-dam period (0.1-0.3 mg L-1). In contrast, median NH4-N concentrations in autumn and spring months were higher after dam construction (0.3-0.4 mg L-1) than before construction (0.13-0.14 mg L-1). Results suggest that beaver dams can increase stream inflow to riparian areas that limit water table declines and increase depths of saturated riparian soils which become more anaerobic, These changes in subsurface hydrology and chemistry have the potential to affect the transport and transformation of nitrate fluxes from adjacent cropland in agricultural landscapes. Copyright (C) 2009 John Wiley & Sons, Ltd.