ABSTRACT

Arsenic is potentially toxic to all lives. Inorganic arsenic exists in the environment in several oxidation states: arsenide (−3), elemental arsenic (0), arsenite (+3) and arsenate (+5) but the latter two are the abundant inorganic forms found in environmental samples. Arsenite [As (III)] is generally regarded as more mobile and 100 times toxic than Arsenate [As(V)] (Knowles & Benson 1983). Arsenic induces both acute and chronic toxicity to the human and animal body. Acute toxicity signs include anaemia, diarrhoea and gastrointestinal discomfort which have been reported in many areas, including Argentina, Taiwan, West Bengal (India) and Bangladesh (Guha-Mazumder et al. 1992). Chronic exposure to inorganic arsenic may trigger a number of adverse health effects including

1 INTRODUCTION

Groundwater arsenic contamination is presently recognised as a worldwide epidemic affecting millions of people in several countries. A large number of aquifers in parts of Argentina, Bangladesh, Chile, northern China, Hungary, India (West Bengal), Mexico, Romania, Taiwan and many parts of the USA have been identified with arsenic contamination at concentrations above the WHO recommended concentration limit for drinking water (10 μg/L). Since the first detection of arsenic in groundwater of Bangladesh in 1993, the country has experienced the biggest arsenic catastrophe in human history in terms of its magnitude, complexity and severity (Khan et al. 2003). Groundwater arsenic mitigation is one of the leading challenges in the twenty first century, especially for developing and poor countries due to resource and other limitations. As the arsenic crisis is largely a natural incident and no protective measures can usually be taken, remediation technologies could be one of the alternatives to curtail the adverse effects.