The Phosphorus Forms and Depositional History in Sediments of Lake Hongfeng, Guizhou Province

Abstract

采集了云贵高原深水湖泊红枫湖现代沉积物未受扰动的柱状样品,通过分析不同形态沉积磷在沉积剖面上的分布特征,并结合沉积物样品柱的²¹⁰Pb、¹³⁷Cs年代学研究结果,揭示了红枫湖现代沉积过程中不同形态沉积磷的早期成岩改造的时间变化序列,以及沉积磷外源输入负荷的历史变化.采用Ruttenberg法分析沉积磷的地球化学赋存形态,研究表明,红枫湖沉积物中有机磷和铁结合态磷是沉积磷的主要赋存形态,分别占沉积全磷的60%和28%.沉积磷在垂直剖面上的分布特征显示,红枫湖现代沉积过程中,沉积磷在最终埋藏前可能发生非常剧烈的形态转化和再迁移,尤其是有机磷和铁结合态磷的成岩改造可能是湖泊系统磷循环质量平衡的重要方面.年代学数据同时表明,近年的人为活动导致湖泊系统(包括沉积物)磷负荷的显著增加.;Phosphorus is one of the important limited elements to lake eutrophication.The regeneration of phosphorus from sediment may be an important phosphorus resource for lakes.Several undisturbed sediment cores have been sampled at the deepest area of a canyon-reservoir, Lake Hongfeng, on Guizhou Plateau, southwestern China.The concentration and distributions of various phosphorus forms in sediment cores have been studied.The chronology data have been obtained by means of ²¹⁰Pb, 13_Cs for the same sediment cores.The geochemical processes of various forms of sedimental phosphorus were mainly controlled by early diagenesis and anthrogenic disturbances on the phosphorus burial in sediment.In our study, the SEDEX method from Ruttenberg has been used to identify the various forms of phosphorus in sediment samples.The species of phosphorus include: loosely sorbed P, Fe-bound P, Ca-bound P, detrial-P and Organic-P.The results showed that the organic-P and Fe-bound P could been seen as two main sorts phosphorus in sediment of Lake Hongfeng, about 60% and 28% in total sediment phosphorus respectively.The forms and vertical distrubition profiles of sediment phosphorus implied that the sediment phosphorus could have strong ability of regeneration during the terminal burial in the bottom of Lake Hongfeng.Under certain conditions, the sediment of Lake Hongfeng could be regarded as the important resource of phosphorus for lake system rather than a sink.