咸水区湿地沉积物磷的吸附与解吸研究

Desorption and sorption of phosphorus in marshland sediments

采用恒温培养法研究美国纽约Pelham Bay Park四种典型湿地沉积物中P的吸附与解吸行为,及其等温吸附曲线与拟合方程。结果表明:在溶液初始P浓度0～100 mg/L时,各沉积物的P吸附量跟初始浓度具有显著的正相关关系;各沉积物的P释放量比较有限,每千克沉积物释P量在0～30 mg之间。用Langmuir和Freundlich等温方程拟合沉积物的P吸附程度,都达到显著水平,R2值分别在0.9372～0.9974和0.9001～0.9915。各沉积物的EPC0大小次序为S2(0.86μg/L)>S1(0.10μg/L)>S3(0.04μg/L)>S4(0.03μg/L)。沉积物的除P能力可根据沉积物最大吸附P量和吸附解吸附平衡浓度(EPC0)来衡量,除P能力大小顺序为S4>S3>S1>S2。原因可能是S4和S3位于咸性水区(pH>7),S1位于酸性(pH=4.1)水区,S2不含有机质。与酸性水区的沉积物相比较,咸性水区具有较强的P吸附能力,同时湿地沉积物释放P量比较有限,因此沉积物释放P而引起区域水体P富营养化的风险性较小。

The objective of this study was to determine the capacity of sorption and release of phosphorus（P） in the marshlands sediments.The sorption characteristics and kinetics equations were obtained by incubating sediments collected from four marshland sites in Pelham Bay Park,New York,USA.The results showed that there was a significant relationship between sorption and original P contamination level in the solution,and the capacity of P desorption in the sediments was limited,which ranged from 0 to 30 mg per kilogram sediment.The adsorption isotherm curves were fit to Langmuir equation as well as Freundlich equation.The EPC0 of the four marshland sediments ranged from 0.03 to 0.86 μg/ L in order of S2（0.86 μg /L）S1（0.10 μg/ L） S3（0.04 μg/ L）S4（0.03 μg/ L）.The capacity of different sediments to sorption P was in order of S4S3S1S2.The difference in sorption capacity might be explained by fact that there is not the organic matter in S2 sediment,and S1 was located in acid area（pH=4.1）,while S3 and S4 were located in alkaline area（pH7.0）.In conclusion,the sediments in alkaline area have the strong ability to sorption P from the solution;the ability to desorption P was comparatively limited.The risk of eutrophic water body caused by P desorption of marshlands sediments in alkaline area was low.