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The arsenic (As) cycle is the biogeochemical cycle of natural and anthropogenic exchanges of arsenic terms through the atmosphere, lithosphere, pedosphere, hydrosphere, and biosphere. Although arsenic is naturally abundant in the Earth's crust, long-term exposure and high concentrations of arsenic can be detrimental to human health. [1] [2]
Arsenic is a ubiquitous naturally occurring chemical element, and the 20th most common element on Earth. [13] Arsenic levels in the groundwater vary from around 0.5 parts per billion to 5000 parts per billion, depending on an area's geologic features, and possible presence on industrial waste.
Arsenic is a moderately abundant element in Earth's crust, and although many arsenic compounds are often considered highly toxic to most life, a wide variety of organoarsenic compounds are produced biologically and various organic and inorganic arsenic compounds are metabolized by numerous organisms.
Research has not been conducted to determine whether small amounts of arsenic may play a role in human metabolism. [17] [18] However, arsenic poisoning occurs in multicellular life if quantities are larger than needed. Arsenic contamination of groundwater is a problem that affects millions of people across the world.
Arsenate is the major arsenic form in oxidizing environments; however, in one study, bacteria from arsenic-contaminated soil at a smelter site was able to reduce As(+5) to As(+3) under anaerobic conditions at arsenic concentration as high as 75 mg/L. [3] Arsenate-respiring bacteria and Archaea have also recently been isolated from a diversity of natural environments, including freshwater ...
Gold mining can contaminate groundwater with arsenic, because the element typically occurs in gold-containing ores. Gold processing releases arsenic from mine tailings, and contaminated groundwater may be unsafe to drink for decades. [6] Arsenic that is naturally occurring can contaminate the soil, just as it does the groundwater.
Contaminated or polluted soil directly affects human health through direct contact with soil or via inhalation of soil contaminants that have vaporized; potentially greater threats are posed by the infiltration of soil contamination into groundwater aquifers used for human consumption, sometimes in areas apparently far removed from any apparent ...
Plants that cause illness or death after consuming them are referred to as poisonous plants. The toxins in poisonous plants affect herbivores, and deter them from consuming the plants. Plants cannot move to escape their predators, so they must have other means of protecting themselves from herbivorous animals.