漳河上游流域沉积物中磷的空间分布特征及其影响因素

漳河上游地区众多的水利工程改变了流域水循环,同时也影响了河流泥沙和生源物质的循环过程。为揭示人类活动干扰下的沉积物中磷的赋存特征,采用改进后的连续化学萃取法分析了漳河上游沉积物中总磷(TP)和磷形态的空间分布特征及其影响因素。研究结果表明,漳河上游沉积物中的TP含量为405.94~899.98 mg/kg,低于我国其他主要河流,接近我国东部平原湖泊含量水平。漳河上游的TP富集指数(PEI)均值为1.15,表明漳河上游富营养化风险较高。可交换态磷(Ex-P)、铁锰螯合态磷(BD-P)、铁铝氧化态磷(NaOH-P)、钙结合态磷(HCl-P)分别占沉积物中TP含量的1.13%、33.96%、12.99%、35.05%。BD-P和HCl-P是沉积物中主要的磷形态,Ex-P的含量最低,NaOH-P的含量波动最大。漳河上游沉积物中,生物可利用磷(BAP)的含量约占TP含量的38.36%~52.04%,其中,清漳干流的BAP含量明显低于其他河段。清漳源头的水土流失及浊漳河的磷输入对漳河上游BAP含量的贡献较大。统计分析显示,漳河上游表层沉积物中,TP和磷形态的空间分布无显著差异,表明以水利工程建设为代表的强烈人类活动对漳河上游沉积物中磷的空间分布的影响不显著。相关性分析和冗余分析表明,沉积物中的NaOH-P含量与沉积物中黏土和粉土的占比有较高的相关性,BD-P和NaOH-P是控制沉积物中BAP构成的重要因素,Fe含量是沉积物中TP含量的主控因子。

Spatial Distribution Characteristics and Influencing Factors of Phosphorus in Surface Sediments of Zhanghe River Upstream Basin

Many water conservancy projects in the Zhanghe River upstream have changed the water cycle in the basin,and also affected the circulation process of sediments and biomass in the river.In order to reveal the occurrence characteristics of phosphorus (P) in the sediments disturbed by human activities,the spatial distribution characteristics and influencing factors of total phosphorus (TP) and P forms in the sediments of Zhanghe River upstream were studied by the improved continuous chemical extraction method.The research results showed that the TP content in the sediments of Zhanghe River upstream was 405.94-899.98 mg/kg,which was lower than other major rivers and closed to the lakes in the eastern plains of China.The average value of TP enrichment index (PEI) of Zhanghe River upstream was 1.15,indicating that its risk of eutrophication was high.Loosely bound P (Ex-P),reductant soluble P (BD-P),metal oxide bound P (NaOH-P) and calcium bound P (HCl-P) accounted for 1.13%,33.96%,12.99% and 35.05% of TP content in sediments,respectively.BD-P and HCl-P were the main forms of P in the sediments,among which Ex-P content was the lowest and NaOH-P had the largest change range.The content of bioavailable phosphorus (BAP) accounted for 38.36%-52.04% of TP,the content of BAP in the main stream of Qingzhang River was obviously lower than that in other rivers,and soil erosion at the headwaters of Qingzhang River and P input from Zhuozhang River contributed more to BAP of Zhanghe River upstream.The results of statistical analysis showed that there was no significant difference in the spatial distribution of TP and P forms in the surface sediments of the Zhanghe River upstream,indicating that the intense human activities represented by the construction of water conservancy projects had no significant impact on the P composition in the sediments.The results of correlation and redundancy analysis showed that the content of NaOH-P in sediments was highly correlated with clay and silt;BD-P and NaOH-P were important factors to control BAP composition;Fe was the main controlling factor affecting TP content.