三峡库区消落带水淹初期土壤物理性质及金属含量初探

Study on the Soil Physical Properties and Metal Content in the Early Submerged Water-level-fluctuating Zone of Three Gorges Reservoir

选取三峡库区消落带内的两种植被类型,沿海拔梯度划分为已淹区段、未淹区段以及对比样带,对其土壤的物理性质和重金属含量进行研究。结果表明:水淹区段内,土壤含水量降低、土壤容重增加、土壤毛管孔隙度和非毛管孔隙度减少、土壤通气度较差,说明季节性水淹导致土壤结构被破坏、土壤质量逐渐变差;土壤pH值整体呈现微酸性,但水淹有使土壤pH值增大,且呈中性的趋势;水淹区段与未淹区段、对比样带相比较,全铜、全铁、全锰、全锌等重金属的含量分别降低了54.97%,2.19%,17.86%,35.29%和66.62%,11.29%,40.93%,18.41%,说明经过水淹后,土壤释放的重金属含量大于从水中吸附的含量,重金属元素流失严重;水淹区段的碱性金属如:全钙、全镁、全钠的含量分别比未淹区段升高了9.1%,8.0%,21.15%;全镁、全钠的含量比对比样带升高了4.5%,25.7%,全钙的含量降低了30.4%。方差分析表明,三峡库区土壤的理化性质随海拔梯度和土壤层次都没有表现出显著的差异性,并且没有形成一致的变化趋势。相关分析表明,4种重金属之间表现为极显著的正相关;3种碱性金属没有表现出相关性;pH值与重金属之间都表现出极显著的负相关。

Secondary bush and abandoned farmland in the backwater area of water-level-fluctuating zone of Three Gorges Reservoir were both divided into submerged area,non-submerged area and contrast area along altitudinal gradients.Soil physical properties and metal content of the different areas were studied.The results showed that soil water content,capillary porosity and non non-capillary porosity decreased while soil bulk density increased,soil aerated capability decreased in submerged area,which illustrated soil structure and quality has been degraded due to seasonal flood.Soil pH values of different areas presented tiny acidity,but it gradually increased and tended to be neutral in submerge area..The content of total copper,total iron,total manganese,total zinc decreased 54.97%,2.19%,17.86%,35.29% and 66.62%,11.29%,40.93%,18.41% by comparing submerged area with non-submerged area and contrast area,which illustrated the content of heavy metal released from soil was higher than that of adsorption from water in the submerged area.And in submerged area,total calcium,total magnesium,total sodium increased 9.1%,8.0%,21.15% comparing to that in non-submerged area.However,total magnesium,total sodium increased 4.5%,25.7%,total calcium decreased 30.4% comparing to that in contrast area.Variance analysis showed that soil physiochemical properties did not present obvious differences,and did not form consistent change trend along altitudinal gradients and soil depth in Three Gorges Reservoir.Correlation analysis showed that there were positive correlative significantly among the contents of four heavy metals while there were no correlative among the content of 3 alkaline metals.There was negative correlative more significantly between pH value and heavy metal content.