Geochemical Sedimentary Records of Eutrophication and Change of Agro-ecological Environment in the Chaohu Lake, East China

  • Li Wu
Keywords: Lake Sediment, Geochemistry, Eutrophication, Agro-ecological environment, Chaohu Lake

Abstract

Samples of lake sediment core were collected from the western part of Chaohu Lake, East China. The
compositions of carbon and nitrogen isotope (δ13Corg and δ15N), total organic carbon (TOC), total nitrogen (TN)
and C/N ratios were then analyzed. By comparing of δ15N and C/N, this paper investigated the origin of
sedimentary organic matter and nitrogen at different depths, and then analyzed the evolution of lake productivity,
the eutrophic status and the change of agro-ecological environment in the Chaohu Lake. The results showed that
the total organic carbon matter was derived mainly from phytoplankton which living on dissolved CO2 from
water, of which the records reflect the flood events for the last 200 years on the basin significantly. Before
1960s, the level of TN was mainly affected by soil erosion, and later was more affected by human activities. In
addition, the sediment organic matter was mainly from the deposition of aquatic plants before 1960s. From
1960s to 1970s, primary productivity increased obviously and eutrophication started. From 1970s to the present,
because the construction of Chaohu Floodgate Station, the replacement of the semi-closed Chaohu Lake is more
slowly, and nutrients are accumulating more rapidly in the lake. These lead to the enhancement of lake
productivity and rapidly development of eutrophication. The reasons are mainly intensified human agricultural
activities and the increasing of exogenous substances input.

Published
2020-02-01