Paper No. 11
Presentation Time: 10:45 AM
HIGH ARSENIC IN ALLUVIAL AQUIFERS IN VARIED CLIMATIC REGIME: HYDROGEOCHEMICAL COMPARISON BETWEEN HUHHOT BASIN, INNER MONGOLIA, PR CHINA AND BENGAL BASIN, INDIA AND BANGLADESH
BHATTACHARYA, Prosun1, MUKHERJEE, Abhijit
2, SHI, Fei
1, XIE, Zheng Miao
3, MUKHERJEE, Arun B.
4, SRACEK, Ondra
5, ZHU, Yongguan
6, BUNDSCHUH, Jochen
7 and JACKS, Gunnar
8, (1)KTH-International Groundwater Arsenic Research Group, Department of Land and Water Resources Engineering, Royal Institute of Technology (KTH), Teknikringen 76, Stockholm, SE-10044, Sweden, (2)Bureau of Economic Geology, Jackson School of Geosciences, University of Texas at Austin, 10100 Burnet Road, Austin, TX 78758, (3)Department of Environmental Science and Engineering, Hangzhou Dianzi University, Xiasha Higher Education Garden, Street No. 2, Hangzhou, 310018, China, (4)Dept. of Biological and Environmental Sciences, University of Helsinki, P.O. Box 27, University of Helsinki, FIN-00014, Finland, (5)Institute of Geological Sciences, Faculty of Science, Masaryk University, Kotlárská 2, Brno, 611 37, Czech Republic, (6)Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing RD, Beijing, 100085, China, (7)Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan City, 70101, Taiwan, (8)KTH-International Groundwater Arsenic Research Group, Dept of Sustainable Development, Environmental Science and Engineering, KTH Royal Institute of Technology, Teknikringen 76, Stockholm, SE-10044, Sweden, prosun@kth.se
Presence of elevated arsenic (As) in the alluvial aquifers of the Ganges-Brahmaputra-Meghna river basin (Bengal basin) and Yellow river basin (Huhhot basin) are well known for about last two decades. The geogenic contamination in both the areas has been largely attributed to the hydrodynamics, including the recharge pattern and hydrochemical cycling. However, while the Bengal basin (BB) is located at low latitude, humid climate (annual mean 1400 mm precipitation) condition, Huhhot basin (HB) is located at the mid latitudes, arid to semi-arid environment (400 mm), indicating a basic difference in the recharge and hence the pattern in hydrological and geochemical cycles. Moreover, BB is comprised of fluio-detlaic deposits derived from Himalayas and the Indian craton in contrast to the Da-Quing Mountain derived fluvio-lacustrine sediments of HB. But interestingly, most of the numerous studies undertaken in BB and limited number of studies done in HB all suggests that microbially catalyzed reductive dissolution of metal oxides and hydroxides present in the organic matter affluent Holocene sediments possibly leads to the mobilization of the As.
The present study tries to understand the nuances of As mobilization in similar redox conditions under a different climatic regime and geologic setting. While BB shows prolific recharge from meteoric and non-meteoric sources, HB probably has a limited recharged, closed inland basin. Arsenic concentrations [mostly As(III)] are higher in the shallow depths of both the dominantly Ca-HCO3- type groundwater of BB and Na-HCO3-Cl water of HB, although the relative percentage of contaminated deeper wells is much higher than in the HB than BB. The maximum concentrations of Fe, Mn, and As are much lower in HB in contrast to BB, which shows a better correlations between As and other redox sensitive related solutes (e.g. Fe, Mn, HCO3), probably indicating a difference in desorption mechanism and metal cycling. This is further suggested by the difference in depth-wise distribution of the solutes in the two regions. Future comparative studies are expected to illustrate the differences between the two locations in greater details with enumeration of the cause for similar mobilization mechanisms.
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