Distribution characteristics of organic phosphorus in the sediments of rivers entering the Lake Hongze and the effects of exogenous substances on their fraction transformation

Abstract

为探究洪泽湖入湖河流沉积物有机磷的空间分布及外源输入对其形态转化的影响，本文利用Ivanoff法开展有机磷形态特征研究，并通过实验室添加常见外源有机质和铁离子，深入探讨外源物质对沉积物有机磷形态变化的长期影响.研究结果表明，洪泽湖入湖河流沉积物有机磷含量范围为34.8~398.6 mg/kg，占总磷的7.7%~36.9%，其中非活性有机磷（NOP） > 中活性有机磷（MLOP） > 活性有机磷（LOP）.濉河沉积物LOP平均占比为19.4%，高于其他河流，而成子河NOP平均占比最高，为56.41%，表明有机磷的空间分布不均匀.总体而言，安河和濉河沉积物中总氮、总磷和有机磷含量显著高于成子河和淮河，显示前两条河流有较高的污染水平.冗余分析表明河流沉积物有机磷形态明显受到其理化性质影响，而不同污染程度沉积物的影响因素有所不同.外源物质添加能够活化沉积物的有机磷，促使NOP向LOP和MLOP转化，有机质输入引起的沉积物有机磷形态变化要大于铁元素输入，而外源物质输入对污染较重河流沉积物的有机磷转化作用更为显著.因此，减少入湖河流周边的外源污染排放是减少湖泊生物可利用磷的有效途径.;In order to explore the spatial distribution of organic phosphorus in the sediments of the rivers entering Lake Hongze and the effects of exogenous inputs on its fraction transformation, we used the Ivanoff method to study the fraction characteristics of organic phosphorus in these sediments. The long-term effects of exogenous substances on the fraction changes of organic phosphorus in sediments were also investigated by adding organic matter and iron ions in the laboratory. The results showed that the contents of organic phosphorus in the sediments of the rivers entering Lake Hongze ranged from 34.8 mg/kg to 398.6 mg/kg, accounting for 7.7% to 36.9% of the total phosphorus, and which showed non-active organic phosphorus (NOP) > middle-active organic phosphorus (MLOP) > active organic phosphorus (LOP). The average proportion of LOP in the sediments of Suihe River was 19.4%, which was higher than that of other rivers. The average proportion of NOP in Chengzi River was 56.41%, which indicated that the spatial distribution of organic phosphorus was uneven. Overall, the contents of total nitrogen, total phosphorus and organic phosphorus in sediments of Anhe and Suihe rivers were significantly higher than those of Chengzi and Huaihe rivers, indicating that the former two rivers had a higher pollution level. Redundancy analysis showed that the fractions of organic phosphorus in river sediments were affected by their physicochemical properties, indicating the different influencing factors for different pollution levels of sediment. The addition of exogenous substances can mineralize organic phosphorus in sediments and promote their transformation from NOP to LOP and MLOP. The change range of organic phosphorus fraction caused by organic matter was greater than that caused by iron, and the transformation effect of exogenous substances on organic phosphorus in heavily polluted sediments was more significant. Therefore, it is an effective way to reduce the bioavailable phosphorus of Lake Hongze by reducing the discharge of exogenous pollutants around rivers.