有机质和低相对分子质量有机酸对沉积物中磷吸附/解吸行为的影响

Effects of Organic Matter and Low Molecular Weight Organic Acids on Sorption and Desorption of Phosphorus on Sediments

研究了水体表层沉积物对磷的吸附特性,以及不同有机质和低相对分子质量有机酸含量对沉积物吸附/解吸磷的行为的影响.结果表明:表层沉积物对磷的吸附行为属于Langmuir型,交换态磷、铁结合磷和钙磷含量在吸附过程后都显著增加;有机质对沉积物中磷的释放有明显的促进作用,相对于腐殖酸,蓝藻更容易促进磷的释放,这可能是因为腐殖酸在释放与Fe、Al等阳离子结合的PO43-、SO42-等阴离子的同时,与部分PO43-发生了作用;当低相对分子质量有机酸浓度为0.01 mol/L时,沉积物的磷解吸量最大,由于低分子量有机酸能活化铁结合磷和钙磷从而提高沉积物中磷的可利用性,所以铁结合磷和钙磷含量明显降低.

Characteristics of phosphorus sorption on surface sediments and effects of organic matter and low molecular weight organic acids on phosphorus sorption/desorption were studied. The results show that phosphorus sorption on surface sediments is well fitted by Langmuir isotherm equation and the content of exchangeable phosphorus （Ex-P）, Fe-bound phosphorus （Fe-P）and Ca-bond phosphorus （Ca-P）increases after sorption. Organic matter significantly accelerates the phosphorus desorption, and the influence of cyanobacteria is more obvious than that of humic acids. The reason is probably that humie acids partly react with PO43- when humic acids release anions （e, g. PO43 and SO42-） combined with cations （e. g. Fe and Al）. Sediments reach the highest phosphorus desorption at 0.01 mol/L low molecular weight organic acids. Because low molecular weight organic acids can increase the availability of phosphorus through activation of Fe-P and Ca-P, the contents of Fe-P and Ca-P decrease.