Hydrochemistry of High-Arsenic Thermal Groundwater of Low-Temperature in the Guide Basin in Qinghai, China
详细信息
- 责任者：Liao Yuan (State Key Lab. of Biogeology and Environmental Geology ; Wuhan 430074 ; China) ; Ma Teng
- 刊名：Hydrogeology and Engineering Geology
- 出版年：2013
- 卷期：40(4)
- 关键词：地下热水 ; geothermal water ; 水化学 ; hydrochemistry ; 青海 ; Qinghai Province
- 页码：p.121-126
- 图表：illus., 1 table, 14 refs.
- 分类号：1005
- issnNo：ISSN1000-3665
- isbnNo：CN11-2202/P
摘要
High-arsenic geothermal groundwater with low temperature is defined as the groundwater containing arsenic of greater than 10 μg/L and having temperature of higher than mean annual temperature and less than 90℃.Since research on the high-arsenic thermal groundwater with low temperature is rare,the Guide basin in Qinghai is selected as a study area to analyze the characteristics of hydrochemistry,arsenic content and isotopic compositions of hydrogen and oxygen.Results indicate that(1) because of Mesozoic Indosinian period granite magma waste heat,the temperature in the thermal arsenic groundwater ranges from 16.3 to 68.5℃ while the content of arsenic is in the range of 10.4~35.4 μg/L;(2) the thermal arsenic groundwater is in an alkaline reductive environment and the pH is higher than 8.The hydrochemical type is complex,in which the main cations are(Na++K+) and Ca2+,and the main anion is HCO-3.(3) The values of δ18O and δD in geothermal arsenic water range from-10.90‰ to-12.32‰ and from-70.1‰ to-84.4‰,respectively,and the d-excess is in the range of 12.78‰ to 15.02‰,which means that the groundwater is mainly recharged by modern precipitation.(4) Compared to high-arsenic groundwater in the Hetao plain in Inner Mongolia and high-arsenic geothermal groundwater in Tengchong in Yunnan,this high-arsenic thermal groundwater of low-temperature is also in a reducing environment,but with low TDS and the different hydrochemistry characteristics,which is be attributed to the different geological backgrounds.(5) The geothermal anomaly not only promotes the horizontal and vertical migration of arsenic in groundwater,the reduction of alkaline environment with the high temperature also promotes the release of arsenic in groundwater,eventually leading to the increase in concentration of arsenic in water.