Agriculture Reference
In-Depth Information
12 Water Supply and Quality
David Werner* and Peter Grathwohl
Abstract
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 comple-
mentary 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 pol-
lutants, 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 seep-
age water and subsequent mobilization of metals.
Introduction
particles, the entrapment of suspended par-
ticles, including bacteria and viruses in the
soil's pore space and the mineralization of
biodegradable matter by soil microorgan-
isms. Soil organic carbon is an important
sorbent matrix for dissolved water contam-
inants, and also an important substrate for
soil biota and a soil habitat-shaping factor. It
is thus an important determinant of a soil's
water filtration capacity. The release of soil
organic matter into soil pore water may,
however, also complicate drinking water
treatment or mobilize pollutants.
Soils are the most important buffer and filter
for water. Water tends to get cleaned and fil-
tered while passing through soil. When
comparing different raw water sources as
potential intakes for drinking water treat-
ment and supply purposes, groundwater
usually provides the better raw water qual-
ity than surface water in terms of colour, tur-
bidity and counts of coliform bacteria. The
soil's water purification capacity depends
on dissolved contaminant sorption by soil
 
 
 
 
Search WWH ::




Custom Search