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受酸沉降和化肥施用等外源性酸输入的影响,三峡库区土壤面临着严重的酸化威胁。通过选取三峡库区两种典型土壤(紫色土和黄壤)作为研究对象,采用酸碱滴定法对土壤酸碱缓冲性能及其影响因素进行了研究。结果表明:在一定的p H范围内,紫色土(p H 6.5~2.5、6.2~11.5)和黄壤(p H 5.6~2.8、5.5~10.7)的p H变化与外源性酸、碱加入量均呈线性相关关系。通过分段拟合获取的缓冲容量结果显示,紫色土酸、碱缓冲容量分别为101.3、34.6 mmol/kg;而黄壤酸、碱缓冲容量分别为105.3、38.0 mmol/kg。黄壤和紫色土主要受碳酸钙与阳离子交换的缓冲作用;缓冲体系及初始p H、机械组成等土壤理化性质的不同是导致库区典型土壤酸碱缓冲容量差异的主要原因,总体表现为黄壤酸、碱缓冲性能略优于紫色土。此外,由于近年来酸沉降和氮肥用量的增加,使得库区土壤面临的酸化威胁呈上升趋势。该结果对库区土壤环境容量和典型土壤酸化潜势等研究具有参考价值,还可为区域外源性酸临界值评估以及应对策略制定提供理论依据。
Affected by acid deposition and exogenous acid inputs such as chemical fertilizers, soils in the Three Gorges reservoir area are under severe acidification threat. By selecting two typical soils (purple soil and yellow soil) in the Three Gorges Reservoir Area as the research object, the acid-base buffer method was used to study the acid-base buffer properties of soil and its influencing factors. The results showed that p H changes in purple soil (p H 6.5 ~ 2.5, 6.2 ~ 11.5) and yellow soil (p H 5.6 ~ 2.8, 5.5 ~ 10.7) All showed a linear correlation. The buffer capacity obtained by piecewise fitting showed that the purple earth acid and alkali buffer capacities were 101.3 and 34.6 mmol / kg respectively, while the yellow soil acid and alkali buffer capacities were 105.3 and 38.0 mmol / kg, respectively. Yellow soil and purple soil were mainly affected by calcium carbonate and cation exchange buffering effect. The difference of physical and chemical properties of soil such as buffer system, initial p H and mechanical composition was the main reason for the difference in acid-base buffer capacity of typical soil in the reservoir area, , Alkali buffer performance is slightly better than purple soil. In addition, due to the increase of acid deposition and nitrogen fertilizer in recent years, the acidification threat to the soil in the reservoir area is on the rise. The results have reference value for the research on soil environmental capacity and soil acidification potentiality in the reservoir area, and provide theoretical basis for the assessment of the exogenous acid threshold and the formulation of coping strategies.