亚热带典型农林流域磷持留时空特征及其影响因素

Spatial-temporal dynamics of phosphorus retention in subtropical agricultural and forestry watersheds:Influential factors and implications

由流域水文过程和地球化学循环所导致的污染物持留是造成面源磷污染治理效果改善缓慢且难以达到预期目标的主要原因.量化流域尺度面源磷持留效应及影响因素是科学实施流域水污染治理的前提.以金井河流域为研究区,利用长期水文、水质定位监测数据(2012—2019年),采用双端元混合模型(E-EMMA)和流量历史曲线法量化了研究区内9个集水区磷持留率(TPRP)时空变化特征.结果表明监测期内9个集水区的TPRP为14.39%~84.07%.不同水文阶段TPRP存在显著差异,表现为低流量阶段(55.07%~86.96%)>中流量阶段(35.45%~74.52%)>高流量阶段(32.54%~55.31%).此外,利用偏最小二乘回归分析方法(PLS),分析了流域特征因子(尺度、土壤、地形、景观格局)对于TPRP的影响作用.在中、低流量阶段,TPRP主要受流域地形和景观格局特征的影响;而在高流量阶段,影响磷持留的主要是流域尺度和景观格局特征.研究结果为洞庭湖磷污染控制与削减攻坚行动制定高效和科学的管控措施提供科学理论基础.

The persistent challenge in mitigating non-point source phosphorus(P)pollution stems from the interplay of hydrological processes and terraforming cycles in watershed,causing the difficulty in achieving the expected goals.Quantifying the non-point source phosphorus retention effect and its influencing factors at the basin scale is the premise of the scientific implementation of watershed water pollution control.In this study,the Jinjing River watershed was used as the research area.Using long-term hydrological and water quality positioning monitoring data(2012—2019),the spatiotemporal variation characteristics of phosphorus retention rate(TPRP)in nine catchment areas in the study area were quantified by using the twoterminal metamodel(E-EMMA)and flow history curve method.The results showed that the TPRP of the nine catchments during the monitoring period was 14.39%~84.07%.There were significant disparities across varied hydrological regimes,which were manifested as low flow(55.07%~86.96%),medium flow(35.45%~74.52%),and high flow(32.54%~55.31%).In addition,the influence of watershed characteristic factors(scale,soil,topography,and landscape pattern)on TPRP was analyzed using partial least squares regression analysis(PLS).In low and medium flow regimes,topography and landscape pattern characteristics of the watershed exerted significant influence on TPRP,whereas In high flow regime,watershed scale and landscape pattern emerged as primary factors.The findings provide a scientific theoretical basis for formulating efficient and scientific control measures for the control and reduction of P pollution in Dongting Lake basin.