Arsenat

Arsenat, or arsenate, is the anion AsO4^3− derived from arsenic acid (H3AsO4) and the family of salts and esters of arsenic acid. In aqueous solution arsenates exist in several protonation states depending on pH, including H2AsO4−, HAsO4^2−, and AsO4^3−, with a tetrahedral arsenic center coordinated by four oxygens.

Common inorganic arsenates include salts such as sodium arsenate (Na3AsO4), calcium arsenate (Ca3(AsO4)2), and ammonium arsenate ((NH4)3AsO4). These compounds form when cations associate with the arsenate anion and are used in various industrial and agricultural contexts. Organic arsenates are esters of arsenic acid and carbon-containing groups; some have been used as pesticides or feed additives, though many such uses are now restricted due to toxicity concerns.

Toxicology and environmental aspects: Inorganic arsenates are toxic and can pose health and environmental risks. Arsenate can disrupt cellular energy metabolism by competing with phosphate in uptake and enzymatic reactions, which can impair ATP production and other phosphate-dependent processes. Chronic exposure to arsenic compounds is associated with adverse health outcomes, including cancer risk, cardiovascular and neurotoxic effects. Environmentally, arsenates can mobilize in water and soils and may accumulate in sediments; remediation strategies often aim to limit mobility and convert arsenate to less soluble forms or reduce it to arsenite for immobilization.

Biology and ecology: Some microorganisms can respire arsenate, using it as a terminal electron acceptor, while others reduce arsenate to arsenite as a detoxification mechanism. In natural waters and soils, arsenate interacts with minerals and organic matter, influencing its mobility and bioavailability.