The lacustrine sedimentary records of coal-burning atmospheric pollution

Based on the studies on diatom, ostracods and magnetism on a core acquired from lacustrine sediments, as well as correlation analysis between concentration of acid diatom and the instantaneous lowest pH value, the processes of environment evolution in Lake Yangzonghai were reconstructed. The lacustrine environment was favorable in the 1950s, and began to be polluted by a coal-burning power plant since 1960. During 1965-1980, the instantaneous lowest pH value of lake water decreased to 5-6 when heavily polluted. There was a decrease trend in the pollution from 1983 to 1999, but coal-burning atmospheric pollution was still a main problem for environmental retrieving. As acid precipitated, acid-tolerant species overspread, and shellfish disappeared, as well as ferromagnetic particulates dissolved because of the consequent change of pH-Eh values in the interface of water and soil, which results in the change of environmental proxies versus depth. Thus, the environmental evolution of Lake Yangzonghai is reconstructed in this paper based on the inferences mentioned above.