广东典型稻田系统磷素径流流失特征

摘要

Three experimental paddy fields located in the city of Zengcheng,Qingyuan and Gaozhou in Guangdong Province were selected to monitor the runoff losses of phosphorus from the year of 2008 to 2012.The results showed that runoff event in paddy field occurred mainly in the early rice season.The runoff concentration of total phosphorus(TP)under conventional fertilization treatment was in the range of 0.02~1.56 mg·L-1.It was recorded that TP concentration in 11%~18%of the total runoff samples exceeded the grade Ⅴof the national surface water environmental quality(0.4 mg·L-1). Peak concentration of different phosphorus forms[TP, dissolved total P(DTP)and particulate P (PP)]were observed within 14 days after fertilization,which indicated the high environmental pollution risk of phosphorus during this period. Application of phosphorus fertilizer increased runoff load of DTP in paddy field and showed no effect on that of PP and TP.The annual runoff loads of 0.63~4.05,0.33~2.91 kg·hm-2and 1.10~6.68 kg·hm-2for DTP,PP and TP,respectively,were recorded under conventional fertilizer model. Runoff load of phosphorus exhibited wide spatial and temporal variation during experimental period. Runoff coefficient of 0.06%~6.81%of phosphorus was recorded.It was observed that DTP dominated the phosphorus runoff load.Phosphorus runoff losses from paddy field was affected by a variety of natural and human factors,and fertilization,precipitation and runoff volume were identified as the main factors.%选择位于广东省增城、清远和高州地区的3个稻田试验点,于2008—2012年对稻田磷径流损失进行动态监测.结果表明,稻田径流事件主要发生在早稻季.常规施肥模式下稻田总磷径流浓度为0.02~1.56 mg·L-1,11%~18%的径流样品总磷浓度超过地表水Ⅴ类水标准(0.4 mg·L-1),施磷后14 d内降雨易导致稻田不同形态磷浓度出现峰值,具有一定环境污染风险.施磷不同程度增加稻田可溶性总磷径流负荷,对颗粒磷和总磷流失负荷无规律性影响.稻田磷径流负荷时空变化较大,常规施肥条件下可溶性总磷、颗粒磷、总磷年径流负荷分别为0.63~4.05、0.33~2.91、1.10~6.68 kg·hm-2.本地区稻田磷流失系数为0.06%~6.81%,可溶性总磷是稻田磷径流流失主要形态.施肥量和降雨、径流量是影响本地区稻田磷径流损失的主要因子.