西洞庭湖湿地Eh与pH空间变异特征及影响因子分析

Spatial Variability Characteristics of Eh and pH in West Dongting Lake Wetland and Analysis of Their Impact Factors

湿地氧化还原电位（Eh）和酸碱度（pH）空间分布特征是探讨湿地污染物存在形态、迁移和转化机理的基础。在湖南省西洞庭湖区澧水和沅水入湖口湿地分别布设2个监测断面共12个钻孔,孔深8.0~14.0m。通过现场和室内试验研究湿地演替带Eh和pH的分布格局和空间变异特征,并对其影响因子进行探讨。结果表明：西洞庭湖湿地演替带监测剖面Eh介于-57.8~238mV之间,平均值为124.67mV,pH值为5.1~9.1,平均值为7.4,属于弱碱性弱还原环境;Eh和pH的变异系数分别为49.60%、11.66%,均表现出中等变异强度;Eh和pH剖面分布特征复杂,均呈夹带斑块的层带状分布;土壤类型、地下水位、含水率和温度均对Eh有重要影响,pH主要受土壤类型和地下水位的制约,温度与含水率对pH的影响不显著。

The spatial distribution characteristics of Eh and pH are the basis of studying contaminant existing form,migration and transformation mechanism in wetland.12 drilling holes of the two monitoring sections are deployed in the estuary wetlands of Li River and Yuan River of the West Dongting Lake,Hunan Province,and the depths of holes are 8.0-14.0m.Distribution pattern and spatial variability of Eh and pH were studied by the site and laboratory tests in the wetland hyporheic zones,and the impact factors were discussed.The results show that the Eh values are-57.8-238 mV with the average of 124.67 mV,and the pH values are 5.1-9.1with the average of 7.4;the hyporheic zone of West Dongting Lake wetland is weak alkaline and reduction environment;the variable coefficients of Eh and pH are 49.60% and 11.66%respectively,and belong to medium intensity variation;the complex profile distribution characteristics of Eh and pH are layer distribution with patches;soil type,underground water level,moisture and temperature have important influences on Eh;pH is mainly affected by soil type and underground water level,whereas temperature and moisture are not significant.