Water Supply and Quality

Water is filtered while passing through soil, and soil organic carbon plays an important role in water purification through the retention of organic and inorganic pollutants. But no filter lasts forever, and no matter how strongly pollutants adsorb to soil organic matter, they will not be retained indefinitely and will eventually break through organic carbon-rich soil horizons and may reach the groundwater. Therefore, the organic pollutant biodegradation in soil by microorganisms is a most important complementary process to pollutant retention by sorption. Soil organic carbon also shapes soil microbial communities and activities as an important substrate and habitat, and forms the metabolic capabilities and activities leading to pollutant breakdown in soils. If released into soil pore water, dissolved or colloidal organic matter may cause problems for drinking water supply as a carrier of associated pollutants, by giving taste, odour or colour to water and through the formation of disinfection by-products. Furthermore, the release of dissolved organic carbon from soils may lead to oxygen depletion in seepage water and subsequent mobilization of metals.