Lake Sediments Record and the Catchment Environmental Changes in the Upper Reaches of the Hangbu River over the Past 50 Years
|School||East China Normal University|
|Keywords||Watershed environmental changes Hangbu River Lake sediments Chaohu SCP Analysis|
The watershed environmental change is a focus on hot issues of today's international research, eastern China, the Yangtze River downstream a monsoon climate significantly stronger areas of human activity to carry out research in this area. Specific river basin the selected Chaohu area the Hangbu River region, the basin surface soil samples and on the acquisition of the the swimming dragon estuary reservoir deposition column like (ALE), X-ray diffraction in the chamber, granularity, environmental magnetism, nutrient elements such as parameters The experimental analysis of the indicators, combined with hydrological data, the basin sediments record past environmental changes in the information collected in the history of literature combined, reconstructed the history of watershed environmental changes the River Hangbu nearly 50 years to explore human activities (agricultural activities) in the past 50 years building a database of watershed environmental impact, with a typical representative of the significance. Through research, the following conclusions and results: (1) analysis, particle size and SCP representative sediment column-like ALE combined the Anhui coal-fired power capacity and runoff data with granularity. The runoff successfully established year resolution to nearly 50 years of modern lake sediments CHRONOLOGIZING. (2) reservoir sediments can objectively record the evolution of the lake environment, combined with the magnetic parameters, the average particle size analysis, reconstruction and human activities in the basin history of environmental change in the past 50 years, and found that the sedimentary environment in the past 50 years can be divided into five stages, each stage of the following characteristics: the first phase (1958 to 1968), due to the combined effect of the relatively less precipitation and human blind reclamation, sediment particles are smaller, higher the x fd < / sub>% value, and an average particle diameter smaller, the lower the C / N value. The second phase (1968 to 1976), mainly due to human impact intensified, serious soil erosion, resulting in the deposition of the stage coarse particles, x significantly increased runoff terrigenous detritus carried warehousing C / N value is a high value. The third phase (1976 to 1979), the stage because of extreme drought, the deposition of particles is significantly less, due to strong evaporation concentrated, making the TN and TP have greatly increased as well as the content of magnetic minerals, are in the high-value segment. The fourth phase (1979 to 1992), due to the artificial remediation, soil erosion eased, a significant reduction of sediment entering the reservoir, terrigenous clastic material is also greatly reduced, the C / N ratio was significantly reduced. The fifth phase (1992 to 2003), the stage due to afforestation and reduction in soil erosion, but in economic development could not handle the waste to the emergence of new deposition sources, siltation phenomenon is still very serious. (3) rainfall and human activity is the main factor to affect the deposition of the basin of the basin's water supplies to rainfall, while the large interannual variability of rainfall in the past 50 years, rainfall appears Feng, low water-alternating change process: year rainfall runoff large, the sediment coarse particles in the reservoir area, terrigenous biodetritus substances more: On the contrary, the stage of low rainfall, the smaller particles, terrigenous biodetritus substances less.