Arsenic Appearance in Groundwater:A Forthcoming Danger in Agriculture

Arsenic is a semi-metallic element-although it is generally referred to as a heavy metal-that occurs naturally in the earth’s crust and has no perceptible taste or odor. In its pure element state, arsenic has a grey colour and is relatively solid. Arsenic is a chemical element with the symbol “As”. Arsenic is recognized as a poison and cancer causing substance (carcinogen). It occurs within organic compounds (combined with hydrogen and carbon), and within inorganic compounds (combined with sulphur, chlorine or oxygen). In water arsenic has no smell or taste and can only be detected through a chemical test. When arsenic combined with other elements in the environment, it changes to a powder form that is either white or colourless and is very difficult to distinguish. This, along with its lack of smell and taste, makes arsenic compounds in water, air, or on food extremely hard to detect. Traces of arsenic can be found in air, soil, water and food. Though naturally occurring arsenic in the soil is usually only found in very low concentrations, some regions of the world contain arsenic-heavy deposits, which have been estimated to tremendously increase arsenic levels in the ground. These arsenic-rich areas have frequently contaminated groundwater supplies, which are often the only source of drinking water for local communities. Arsenic contamination of groundwater is a form of groundwater pollution which is often due to naturally occurring high concentrations of arsenic in deeper levels of groundwater. It is a high profile problem due to the use of deep tube-wells for water supply in the Ganges Delta, causing serious arsenic poisoning to large numbers of people. A 2007 study found that over 137 million people in more than 70 countries are probably affected by arsenic poisoning of drinking water. Arsenic contamination of groundwater is found in many countries throughout the world, including USA.