摘要
在放射性核素137Cs和210Pb精确计年的基础上,建立了长江中游网湖近代沉积物年代序列。通过对沉积物中TOC、TN、TP、孢粉、重金属元素、粒度等指标的测定,结合相关文献资料,分析了百年来网湖沉积物中营养元素的分布特征,物源变化以及主控因子。结果表明:百年来网湖沉积物中TN和TOC含量显著相关,呈不断上升趋势,存在2个明显的演化阶段,主控因子为流域人类活动强度,气候波动对其有影响,但影响不大。TP的变化与TN和TOC明显不同,波动较大,规律不明显,主要受人类活动强度以及径流侵蚀输移入湖物质变化两大因子控制。
Sediment cores were collected in November 2007 from Wanghu Lake,a river connecting lake before 1960s,in the middle reaches of the Changjiang （Yangtze） River.Dating sequence of the core was established based on radioisotopes 137Cs and 210Pb.The samples of the core sediments were analyzed for total organic carbon （TOC）,total nitrogen （TN）,total phosphorus （TP）,heavy metal,grain-size and pollens.The results show that two stages were recognized according to vertical variation of TOC and TN concentrations.Before 1950,both TOC and TN concentrations were low and stable,reflecting that the TOC and TN of sediment were mainly from the natural of soil nutrient cycling in surrounding.After 1950,the concentrations of TOC and TN were increasing,the maximum appeared in the surface of sediment.The vertical changes of TP was different from TN and TOC,and it was more complex relatively.Before 1920,TP concentrations were low and sable,and in the period 1920-1950,TP concentrations were lower which were probably resulted from the decline of economy and population of the Yangxin County caused by war,Schistosomiasis and frequent floods.From 1950 to 1970,with the hydraulic engineering constructions,the development of industry and agriculture,the concentrations of TP in sediment were notable increased.Since Fuchi floodgate had been finished in 1967,the lake water exchange from the Changjiang （Yangtze） River was blocked,fine soil and particle phosphorus decreased into Wanghu Lake from Changjiang River,and the concentrations of TP in the sediment was declined.The results from Principal Component Analysis show that the concentrations of TOC and TN in sediment were mainly controlled by human activities and the changes of catchment land use,and climate had little impacted on them;the concentrations of TP were drove by two factors of human activities,erosion and transportation of runoff in catchment and the Changjiang River.
出处
《地理科学》
CSCD
北大核心
2010年第5期766-771,共6页
Scientia Geographica Sinica
基金
国家杰出青年科学基金(40825004)项目资助
关键词
网湖
营养元素
演化
影响因子
Wanghu Lake
nutrient element
evolution
influential factors
