Organochlorine compounds and the biogeochemical cycle of chlorine in soils: A review

Abstract

Chloride ions in soil may interact with soil organic matter and form organochlorine compounds in situ. The biotic chlorination of soil organic substances takes places under aerobic conditions with participation of H₂O₂ forming from peroxidases released by soil microorganisms (in particular, by microscopic fungi). The abiotic chlorination results also from the redox reactions with the participation of Fe³⁺/Fe²⁺ system, but it develops several times slower. Chlorination of soil organic substances is favored by Cl^– coming to soil both from natural (salinized soil-forming rocks and groundwater, sea salt) and anthropogenic sources of chlorides, i.e., spills of saline water at oil production, road deicing chemicals, mineral fertilizers, etc. The study of the biogeochemical chlorine cycle should take into account the presence of organochlorine compounds in soils, in addition to transformation and migration of chloride ions.