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区域环境与生态

Phosphorus concentrations in surface runoff and subsurface flow from agricultural catchments by the Yuqiao Reservoir

摘要：选择天津市重要饮用水水源地于桥水库周边2个农业小流域,连续5a进行了磷素流失的实验研究.结果表明,地表径流总磷浓度以果园为最高,浓度超过10mg·L^-1;村庄次之;农田最低,浓度在3mg·L^-1左右.降雨后亚表层流中磷浓度以果园为最高,且变幅最大,菜园次之,农田最低.在流域出口处,曹各庄流域地表径流总磷浓度达到10.07mg·L^-1,而桃花寺流域为0.69mg·L^-1.土地利用类型格局和迁移廊道性质是造成2个流域磷素浓度差异的主要原因:曹各庄流域中村庄和果园同水库较近的距离(约200m),以及道路型季节性河流增加了磷素迁移到受纳水体的风险;桃花寺流域中村庄和果园离受纳水体较远(约1500m),在迁移过程中磷素被小石坝、植被过滤带和干塘等"汇"型结构所持留,从而减少了向受纳水体迁移的风险.

Abstract：Afield study on phosphorus loss characteristics was conducted over 5 years in two agricultural catchments by the Yuqiao Reservoir,the drinking water source area for Tianjin City.Total phosphorus concentration(TP) in the surface runoff of orchards was the highest among five kinds of land uses(mean concentration above 10 mg·L^-1),that of village was the second highest and that of cropland was the lowest at a level of about 3 mg·L^-1.The phosphorus concentration in subsurface flow of orchards was the highest,that of vegetable gardens was the second,and that of cropland was the lowest.TPin surface runoff at the outlet of the Taohuasi catchment amounted to 10.07 mg·L^-1,while that of the Caogezhuang catchment was 0.69 mg·L^-1.Different landscape spatial patterns and water transport pathways were responsible for this gap.The short distance(about 200 m) between the village and the receiving water and the "road" type transport pathway in the Caogezhuang catchment increased the nutrient discharge load.The longer distance(about 1500 m) from the village and orchard in the Taohuasi catchment to the receiving water increased the phosphorus transport pathway.And small stone dams,a vegetated filter strip and dry ponds within the ephemeral stream could retain nutrients in the Taohuasi catchment.

Key words：agricultural catchment phosphorus surface runoff subsurface flow concentration pathway