洱海沉积物重金属地球化学相及其污染历史研究

高原封闭、半封闭型湖泊是气候和环境演化的敏感指示器，其沉积物记录具有连续性、敏感性和高分辨率的特点。高原湖泊沉积记录在恢复和重塑各种短时间尺度（千年、百年、十年）的气候和环境演化序列上，具有其它自然历史记录无法替代的优势，尤其在揭示近代环境污染历史方面更有其独到之处。本文通过对洱海沉积物重金属地球化学相的研究，利用因子分析方法，识别了沉积物重金属的主要来源和影响其分布的主要因素，即：流域侵蚀作用、大气沉降作用、工业废水与生活污水的排放，以及早期成岩作用。同时，结合沉积物柱芯210PBex计年结果，本文初步评价了洱海150多年来的重金属污染历史：1958年以来．因为化石燃料使用量的增加．洱海湖区大气污染日趋严重；1982年后，由于西洱河水电站的建成运行和湖区植被的破坏，流域侵蚀作用显著加强，应当引起重视。

GEOCHEMICAL PHASES AND POLLUTION HISTORY OF HEAVY METALS IN SEDIMENTS OF LAKE ERHAI

The enclosed or semi-enclosed plateau lake, whose sediment records can provide us with plenty of fine and high resolution information, is a sensitive indicator of climaic and environmental changes. During the reconstruction of various short-time-scale(for example, thousand, hundred or ten years) climatic and environmental changes, the geochemical in plateau-lake sediments are superior to other naural files, especially in indicating recent pollution history. Based on the geochemical phases of heavy metals such as Fe, Mn, CU, Ni, Pb and Ce in the sediments of Lake Erhai in the Yunnan-Guizhou Plateau, this paper, using factor analysis, identifies the main sources of heavy meals in the sediments and factors affecing their distributions including catchment erosion, air deposition, discharge of indusrial wasewater and domesic sewage, and diagenetic modification. At the are time, the 210Pb method is used to calculate sediment accumulation rates and develop chronological information in the sediment core. On the basis of factor analysis and dating, this paper evaluates the changing dominant sources of heavy metals and reveals the pollution history of heavy metals in the area. The following results and conclusions are drawn.1. Catchment erosion is a decisive facor affecting the distribution of heavy metals in lake sediments.2. Afer 1958, air pollution became serious in the me because of burning of fossil fuels (oil, coal and naural gasee) on a large scale.3. As a result of the consruction of the Xierhe Hydroelectric Station and the destruction of vegtation,catchment erosion has been becoming stronger since 1982, to which more attention should be paid.4. Lake sedimentation is a continuous accumulation process, so we should be prudent in determining the time of the strongest diagenetic modification.