Geology Reference
In-Depth Information
2.3 Confi ned aquifers
Confined aquifers, which have a low Redox Potential due to the
consumption of dissolved oxygen, then of nitrates, by oxidation reactions
with sulfur or with organic material, are sites where undesirable metals go
into solution (iron and manganese). If the reduction conditions are more
severe, ammonium, sulfi de, and methane can appear.
2.4 Natural organic material
Alluvial aquifers, where rivers have brought in various organic debris
(wood, leaves), can have elevated total organic carbon (TOC) or hydrocarbon
levels, of the same order of magnitude as those caused by low levels of
anthropogenic pollution.
3 ANTHROPOGENIC POLLUTION
Human activities produce gaseous, liquid, and solid wastes that are dumped
into the environment (atmosphere, surface water, soil, groundwater) and
which, directly (dumping) or indirectly, will affect groundwater. Vertical
(recharge) or lateral (limits on infl ows: riverbanks) infi ltration, and leaching
of the the atmosphere and of the soil, will all contribute to the degradation
in quality of resources.
3.1 Domestic pollution
The principal pollutants are salts (sodium chloride from ion-exchange
resin devices in water softeners, clothes irons, or dishwashers), surfactants
(borates, polyphosphates from detergents), bacteria ( Escherischia coli , fecal
coliforms), hormones (birth control pills). Aside from ions in solution,
domestic pollution also includes particles in suspension, particularly
organic material. In addition, there are do-it-yourself repair materials (paint
thinners, motor oil), and fertilizers and pesticides, which are heavily used
in private gardens.
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