Hyporheic processes during flooding and drying in a Sonoran Desert stream. I: Hydrologic and chemical dynamics
Hyporheic processes during flooding and drying in a Sonoran Desert stream. I: Hydrologic and chemical dynamics
复制标题
索诺兰沙漠溪流洪水和干燥过程中的潜流过程。
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
A. Boulton
中科院分区：
文献类型：
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作者：
E. Stanley;A. Boulton
我们在三个不同流动方式的地点研究了洪水和长时间干燥对索诺兰沙漠小溪潜流带间隙水化学的影响。采样在冬季洪水使原本干燥的溪流重新湿润后立即开始，并在170天后夏季山洪摧毁了许多采样井后结束。在研究初期，所有站点的硝态氮、可溶性活性磷(SRP)和溶解氧浓度较高，而氨氮浓度较低。随着流量的减少和干燥的开始，潜水(>；50厘米深)和洪积(活动河道侧面)亚系统中的营养盐和溶解氧浓度下降，而浅层(<；50厘米)样品保持良好的含氧量。缺乏地表径流的区域(干通道低孔道)的水化学成分因站点而异；硝态氮和溶解氧在一个站点减少，在另一个站点增加。随着持续干旱，潜水和冲积物生境变得极度缺氧(<；0.50 mg/L溶解氧)和低硝酸盐氮(<；0.02 mg/L)，这是由于表层和潜水之间的水文交换减少所致。缺氧面积的增加明显增强了潜水和冲积生境中的硝酸盐还原转化，因为间隙中的硝态氮浓度往往低于表面值；因此，干燥导致这种N限制的溪流中的功能转移，因为浅水区从硝酸盐源转变为硝酸盐汇。潜流亚系统的边界随着洪水和干旱的响应而波动很大，这突显了水文极端对地表水流和潜流带之间化学联系强度的重要性。
We examined the effects of flooding and prolonged drying on interstitial water chemistry in the hyporheic zone of a Sonoran Desert stream at three sites with different flow regimens. Sampling began immediately after a winter flood rewetted the previously dry stream, and ended when a summer flash flood destroyed many sampling wells 170 days later. Nitrate-N, soluble reactive phosphorus (SRP), and dissolved oxygen concentrations were high whereas ammonium-N was low at all sites at the beginning of the study period. As discharge declined and drying began, nutrient and dissolved oxygen concentrations declined in phreatic (>50 cm deep) and parafluvial (lateral to the active channel) subsystems while shallow hyporheic (<50 cm) samples remained well-oxygenated. Hyporheic water chemistry in areas lacking surface flow (the dry channel hyporheic) varied between sites; nitrate-N and dissolved oxygen decreased at one site but increased at another. With continued drying, phreatic and parafluvial habitats became extremely hypoxic (<0.50 mg/L dissolved oxygen) and low in nitrate-N (< 0.02 mg/L) due to reduced hydrologic exchange between surface and hyporheic waters. The increased area of hypoxia apparently enhanced nitrate-reducing transformations in phreatic and parafluvial habitats because interstitial nitrate-N concentrations often were lower than surface values; thus, drying caused a functional shift in this N-limited stream as the hyporheic zone changed from a nitrate source to a nitrate sink. Boundaries of hyporheic subsystems fluctuated considerably in response to flooding and drying, underscoring the importance of hydrologic extremes to the strength of chemical linkages between the surface stream and the hyporheic zone.