水流扰动强度对农村沟渠底泥磷释放的影响

The Effect of Water Flow Disturbance Intensity on Phosphorus Release from Sediment in Rural Ditches

采用自制模拟装置的方式,通过设置沟渠水体不同的水流扰动强度(静置、5、15、30、60 L/h),探析在不同水流扰动强度下底泥磷形态的迁移转化规律及水体磷浓度的变化差异。结果表明:静置至15 L/h的水流扰动强度促进底泥磷释放,30~60 L/h的水流扰动强度抑制磷释放,其中15 L/h的水流扰动强度下,水体总磷释放量、释放速率最大;在水流扰动影响下,底泥全磷、弱吸附态磷、可还原态磷及钙结合态磷,均在一定程度上释放,全磷释放量随扰动强度加强呈现先增大后减小的规律,3种磷形态释放规律各不相同,其中水体总磷与第30天的可还原态磷、钙结合态磷具有极显著正相关(P<0.01);底泥中磷形态受水流扰动影响,由活性磷向非活性磷转化趋势明显,磷活性比随水流扰动强度的增大表现出先减小至15 L/h后增加的趋势。因此,15 L/h的水流扰动强度一定程度上可以治理沟渠底泥P污染、降低沟渠底泥生态风险。

Simulator was adopted to set different water flow disturbance strengths(0,5,15,30,60 L/h),analyzes the migration and transformation of P forms and the changes of P concentration in the sediments under different water disturbance intensity.The results showed that the water flow disturbance intensity of 0-15 L/h promotes the release of P from the sediment,and 30-60 L/h inhibits the release of P,15 L/h of water disturbance intensity caused the maximum release amount and release rate of TP in water.Under the influence of water disturbance,the TP,weakly adsorbed phosphorus(Labile-P),reducible phosphorus(RSP)and calcium-bound phosphorus(Ca-P)of the sediment were released to some extent,and the TP release increased first then decrease with the disturbance intensity,and the release patterns of the 3 P forms were different,and the TP in the water was significantly positively correlated with the RSP and Ca-P on the 30th day(P<0.01).The P form in the sediment is affected by the water flow disturbance,and the conversion trend from active P to inactive P is obvious.The P activity ratio decreases firstly then increases in the 15 L/h water flow disturbance intensity.It showed that the water flow dis-turbance intensity could control the P pollution of the ditch and reduce the ecological risk of the ditch sediment to a certain extent.