洞庭湖区浅层地下水氧化还原分带规律

Redox zoning of shallow groundwater in Dongting Lake region

在收集洞庭湖区1258个浅层地下水样检测数据的基础上,利用地统计学克里金方法分析Eh的空间分布规律,并基于氧化还原敏感指标的浓度空间数据对湖区地下水系统开展氧化还原分带规律研究.结果表明,受地质构造、地层岩性特征、沼泽湿地与水稻田等因素的控制,自湖区外围山地和丘陵区至洞庭湖腹地,Eh值呈现逐渐减小的趋势,地下水环境逐渐由外围的氧化环境转为湖区腹地的还原环境;洞庭湖区地下水系统可分为硝酸盐稳定及还原带、锰(Ⅳ)还原带和铁(Ⅲ)还原带等3个氧化还原带.3个分带较好地反映了Eh的空间分布规律,但是在部分区域受含水层介质Mn元素富集的影响,氧化还原分带与Eh的空间分布存在错位现象.

Based on the 1258 shallow groundwater samples of Dongting Lake region,the spatial distribution of Eh was analyzed by geostatistical method,and the redox zoning of groundwater system in the lake region was carried out by using the concentration spatial data of redox sensitive indexes.The results show that,controlled by geological structure,stratigraphic lithology,swamp wetland and paddy field,spatial distribution of Eh in Dongting Lake region shows a decreasing trend from hilly areas to the hinterland of the lake,which reflects a fact that,groundwater environment gradually changes from relative oxidation to relative reduction.Groundwater system in Dongting Lake area can be divided into three redox zones,which arestable and reductive zone,manganese(IV)reductive zone and iron(III)reductive zone.In general,the three zones reflect the spatial distribution of Eh well,although the zones and Eh are not in synchronizationin some regions for Mn enrichment in aquifer media.