The Seasonal Change And The Environmental Effects Of Dissolved Organic Carbon In Soil Of Mao Village

Dissolved organic carbon (DOC) is an important part of soil carbon pool. Because of its specialties of instability, easily being decomposed and oxidized and the environmental sensitivity, DOC has been the research focus of the global carbon cycling. It has the practical signification on the research of transference of soil nutrient,biochemistry procession of soil organic matter and pollution.To understand the dissolved organic carbon's seasonal dynamic change in the soil of karst and non-karst region , and the function of dissolved organic carbon to nutrient elements'character of release and supply in soil and to the process of karst erosion, we took the lime soil and red soil of Mao village, Chaotian, Lingchuan County, Guilin, Guangxi for research objects, observing the dynamic change in season and the environmental effects of dissolved organic carbon in the soil of karst and non-karst region., so as to provide some scientific foundation for future relational research and the soil melioration in karst region.Study methods: field inspection and simulate experiment in room were being done. Selected two sites with similar vegetation communities in lime soil from limestone (D3r) and in red soil from sandstone and shale containing iron ore (D2l), then made profile and buried carbon dioxide tubes in each point. Limestone normal test-slices were buried at the same time. Determined the concentration of carbon dioxide in soil, soil respiration, the content of water in soil and the soil pH twice every month. And the concentrations of DOC, DON, microbial carbon, nitrogen and N, P, K, Ca, Mg in soil sample were mensurated at the same time. Replaced the test-slices and measured their erosion rates every three months. The field survey persisted for one year. On simulate experiment in room, we made dissolution test in self-made equipment with the 0.25mmol/L solutions of several low molecular weight organic acids, including oxalic acid, formic acid, acetic acid, citric acid, lactic acid, pyruvic acid effecting on lime rock granule with diameter range from 0.45 to 1mm. The whole experiment were conducted at the temperature of 25℃.The study results showed that: 1. The DOC contents in lime soils were far less than in red soils due to high content of humus acid in organic matter, because humus acids react with the high...