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NATURAL ARSENIC IN GROUNDWATER: OCCURRENCE, REMEDIATION AND MANAGEMENT - CHAPTER 34 (end)

Asen vượt quá giới hạn cho phép từ nước giếng ống đã được báo cáo từ các tiểu lưu vực sông Yamuna, bước đầu đã đem lại cho nước uống. Vị nước giếng ống an toàn bằng cách sử dụng phần mềm MODFLOW có thể cung cấp cho khắc phục lâu dài. Hydrostratigraphy của lĩnh vực nghiên cứu là khái niệm độ sâu 140 m và ba nhóm trầm tích chủ yếu được xác định tức, đất sét, cát, và cát sỏi. Nghiên cứu này chỉ ra rằng nồng độ asen trong trầm tích và nước ngầm không tiết lộ. | Natural Arsenic in Groundwater Occurrence Remediation and Management -Bundschuh Bhattacharya and Chandrasekharam eds 2005 Taylor Francis Group London ISBN 04 1536 700 X Prerequisite studies for numerical flow modeling to locate safe drinking water wells in the zone of arsenic polluted groundwater in the Yamuna sub-basin West Bengal India Soumyajit Mukherjee Department of Earth Sciences Indian Institute ofTechnology Roorkee Roorkee Uttaranchal India ABSTRACT Arsenic beyond permissible limit from tube-well water has been reported from Yamuna sub-basin which was initially giving potable water. Locating safe water tube-wells using MODFLOW software can give long-term remedy. Hydrostratigraphy of the study domain is conceptualized up to a depth of 140 m and three principal sediment groups were defined viz. Clay Sand and Sand and Gravel. This study indicates that the arsenic concentration in sediment and groundwater does not reveal depth-wise trend. Deviation Factor DF indicates irregular trend of concentration levels in sediment as well groundwater depth-wise. Statements on acquisition of arsenic free groundwater are site-specific. These necessitate modeling based decision making for safe well location. Secondly all the DF values are negative which means that arsenic in sediments is depleted with respect to their world average values. To locate safe drinking water wells in the Yamuna sub-basin the modeler should incorporate depth specified hydro-stratigraphy and field constraints. This will be followed by calibration of other hydrological parameters to simulate observed arsenic spreading responsible for its sporadic nature. 1 INTRODUCTION In the Bengal Basin in has been reported that even the deeper aquifers have been contaminated with arsenic above the permissible limit Muralidharan 1998 Mukherjee et al. 1999 Burgess et al. 2000 Bhattacharya et al. 2002a b Ahmed et al. 2004 . The importance of numerical modeling in locating deep aquifers free from arsenic contamination