WATER POLLUTION
Chapter 11
WATER POLLUTION
Any contamination of water that lessens its value to humans
and other species, aquatic and non aquatic.
Classification:
By the source
By the chemical
POLLUTION ROUTES
• Surface water
• Bodies of water that have direct contact with the atmosphere
• Ground Water
• Water found in the ground, either in saturation or deep
deposits
POINT SOURCE
• Well defined location (a point)
• Sewage treatment or factory/plant waste
• Discharges straight into surface or ground water
NONPOINT SOURCE
• Do not come from distinct points
• Comes from farmland area where pesticides and artificial
fertilizer are used
• Chemicals can drain/leach into ground water or into surface
water
CHEMICAL TYPE CLASSIFICATIONS
• Sediment
• Inorganic nutrients
• Thermal pollution
• Disease-producing microorganisms
• Toxic organic chemicals
• Heavy metals
• Oxygen-demanding organic wastes
SEDIMENTATION
• Sand, silt, and clay eroded from soils and washed from
roadways
• 0.9 billion metric tons of soil are washed into our aquatic
systems in the US annually
• The Mississippi River carries 210 million metric tons into the
Gulf of Mexico each year
WHERE DOES SEDIMENT COME FROM
• Natural stream bank erosion
• Wind erosion
• Farmland
• Construction sites
• Timber harvesting
• Strip Mining
HARMFUL EFFECTS OF SOIL EROSION
• Sediment will damage turbines in hydroelectric plants
• Harbors and river channels must be dredged periodically
• Soil can often times carry chemicals and pesticides
• Suspended solids block sunlight which kill algae
• Reduces oxygen
• Kills bacteria
CONTOUR FARMING
• Plowing, seeding, cultivating and harvesting at a right angle
to the direction of the slopes
• Jefferson practiced this method
• Most farming years ago went up and down slopes
STRIP CROPPING
• Growing crops that different types of tillage (one row crop
alternated with one cover crop)
• Crops are sown along contours or across the prevailing wind
direction to decrease soil erosion by water & wind
• Example:
• Row crop (corn, potatoes, tobacco)
• Cover crop (hay, soybeans)
TERRACING
• Practiced by Incas and Peru and by the ancient Chinese
• Limited land space due to populations
• Tilled into the mountains
• Allows the whole surface to be farmed
• Benched terraces can allow water to stay on a surface
• Rice fields
GULLY RECLAMATION
• Gullies are erosion channels too large to be erased by
ordinary farming operations
• They are active when their walls are free of vegetation
• Must be plowed and seeded at first notice
CONSERVATION TILLAGE
• Plowing with different types of blades to reduce soil erosion
• No till practices
• Leave at least 30% of the crop residue
• Farmers are encourage to practice this method