盐碱地稻田径流中磷素的动态变化特征及其潜在环境效应

摘要

[目的]研究盐碱地稻田径流中磷素的动态变化特征及其潜在环境效应.[方法]以松嫩平原苏打型盐碱地前郭灌区为研究对象,探讨了不同灌溉条件下稻田径流中磷素的动态变化规律及其潜在环境效应.[结果]盐碱地稻田表水呈碱性,土质分散,保肥能力差;土壤总磷在表层富集,增加了磷素随径流流失的风险.稻田磷素流失的主要时期为灌溉期及暴雨径流发生期,稻田径流中总磷、颗粒态磷、总溶解态磷和溶解性活性磷的浓度均随时间的推移呈下降趋势,磷素流失以颗粒态磷为主,而且磷素浓度均超过导致富营养化发生的临界值,直接影响下游查干湖的水质安全.各退水渠磷素浓度均随时间的推移而增大,并在高温时期出现不同程度的富营养化现象;各稻田表水与退水渠总磷浓度呈高度负相关,相关系数R2(α=0.05)分别为0.850 9、0.896 4和0.915 3.灌排条件最好的稻田磷素流失负荷较大,污染风险等级最高,应作为磷素输出的关键源区进行重点监控和防治.[结论]该研究为合理开发盐碱地资源、制定盐碱地最佳磷素管理措施、控制农田磷素流失和保护当地水资源提供了理论依据.%[ Objective] The aim was to study the dynamic variation characteristics of phosphorus in paddy field runoff in saline land and its potential environmental effect. [ Method ] Taking Qianguo irrigation district in soda-saline land in Songnen Plain as study object, the dynamic variation law of phosphorus in paddy field runoff under different irrigation conditions and its potential environmental effect were discussed.[ Result ] Surface water in paddy field was alkaline,and scattered soil had poor fertilizer conservation capacity, while total phosphorus (TP) accumulated in soil surface layer, which could increase the risk of phosphorus loss with runoff. Phosphorus loss in paddy field mainly occurred in irrigation period and rainstorm runoff period, and the concentration of TP, particulate phosphorus ( PP), total dissolved phosphorus (TDP) and dissolved reactive phosphorus (DRP) in paddy field runoff decreased with time, especially PP, while phosphorus concentrations exceeded critical values resulting to eutrophication, which affected water quality safety in Chagan Lake. Phosphorus concentrations in water recession canal increased with time, and eutrophication with different degrees appeared under high temperature; TP concentration in surface water in paddy field was highly negatively correlated with that in water recession canal, and the correlation coefficients R2 ( a = 0. 05 ) in three paddy fields were 0.850 9, 0.896 4 and 0. 915 3, respectively. The loss load of phosphorus in paddy field with the best irrigation condition was higher,and its pollution risk grade was the highest, so it should be monitored and controlled mainly as the critical source area of phosphorus loss.[ Conclusion ] The study could provide theoretical foundation for developing saline land rationally, establishing optimal management measure of phosphorus in saline land and controlling phosphorus loss in farmland to protect local water resources.