洪湖历史时期人类活动的湖泊沉积环境响应

以洪湖北部和南部两个短柱钻孔(HN和HS)研究湖泊沉积，采用137Cs定年，沉积速率为0.155 cm/a。沉积物的总有机碳、总氮、磷以及元素和磁化率等指标分析表明：1840年前洪湖地区人类活动较弱，在湖泊沉积物中基本没有早期的人类活动信号的记录；1840年以后由于人口大量增加，人类活动增强，湖泊的营养水平有所增加，尤其是1950年以来沉积物中营养元素急剧增加；近50年来的湖泊营养程度的加重主要与流域内大量营养物质进入湖泊，以及大面积的围垦造成湖泊面积减小、自我调节能力降低有关。洪湖两孔的对比研究表明，不同区域之间存在着差异，可能与洪湖湖流作用及人类活动的影响差异有关。

HUMAN IMPACT RECORDED IN THE SEDIMENT OF HONGHU LAKE

Two short sedimentary cores were collected from Honghu lake named HN and HS. The total organic carbon, total nitrogen, phosphorus, susceptibilities, elements and partial size were analyzed. Combining with 137Cs dating, the results indicated that nutrient evolution succession of historical period can be divided into three stages. Before 1840 the lake was characterized with lower productivity, during about 1840~1950 there was an obvious increase of organic production because of population increase. Since 1950, human impacts have accelerated the lake′s trophic status. Large amounts of carbon, nitrogen, phosphorus have accumulated in the sediment. The accumulation of these nutrients is considered to be the discharge of sewage water from multiple sources and cultivation of the lake. The comparison of indices of the two cores shows that district difference does exist due to the inlet water flow, matter source and human impacts. It can be concluded that the human impacts have greatly disturbed the process of natural environmental evolution of Honghu lake.