Transcript Pesticides in the Environment

Pesticides in the
Environment
SOURCES OF CONTAMINATION
• Point-source pollution - comes from a
specific, identifiable place
– Clean-up, storage, disposal
– Most common source of pollution
SOURCES OF CONTAMINATION
• Non-point-source pollution - comes from a
wide area
SENSITIVE AREAS
Outdoors
• Ground or surface water
• High traffic areas
– Playgrounds
• Animal and insect habitats
– Honeybees
• Crops and gardens
SENSITIVE AREAS
Indoor
• Sensitive people
– Elderly, pregnant, children
• Domestic animals
– Pets
• Food storage - kitchen
SENSITIVE AREAS
• Buffer zone: an untreated area around
border of sensitive area
PESTICIDE MOVEMENT
Air
drift: movement away from target site via air
• Droplets
– Dusts and spray
• high pressure nozzles create small droplets
• Vapors
– fumigants
PESTICIDE MOVEMENT
Water
• Runoff
– Streams and ponds
• Leaching
– Percolating through soil into groundwater
PESTICIDE MOVEMENT
On or in Objects, Plants, or Animals
• Stick to clothes, animals, shoes
• Residues on crops and fruit
HARMFUL EFFECTS ON NONTARGET
Direct contact with non-target
• Drifting to non-target
• Runoff to aquatic
HARMFUL EFFECTS ON NONTARGET
Residue, causing later injuries
• Residue is the chemical that remains
• Pesticides turn into harmless by-products
over time
HARMFUL EFFECTS ON NONTARGET
Residue, causing later injuries
• Persistent pesticides
– Stay in environment long time
• ADV: fewer re-applications
• DISADV: later affect sensitive plants and
animals
– Biomagnification and accumulation, DDT
HARMFUL EFFECTS ON NONTARGET
Surfaces
• Pesticides can discolor or corrode surfaces
Special Environmental Concerns
• Ground water
– Especially
• Groundwater close to the surface
• Soil is sandy
• Endangered species
PROTECTING GROUND WATER
• Water in rock and
soil
– Located in soil pore
space
– Underground
streams flow
through limestone
-Aquifer: provide
well water
SOURCES OF GROUND WATER
• Rain, lakes and streams
• Water moves through the soil until
saturated zone: water table
Factors that affect pesticide
movement
Pesticide user
• Mixing, storage, and disposal
Factors that affect pesticide
movement
Water on treated surface
• Weather and irrigation practices
Factors that affect pesticide
movement
Pesticide factors
• Solubility - readily dissolved in water
• Adsorption - attachment to soil particles
– High adsorption lowers pesticide mobility
• Persistence - time to break down into byproducts
Factors that affect pesticide
movement
Soil factors
• Texture - proportions of sand, silt, and
clay
– Clay moves water and pesticides slower
– Sand moves faster
• Permeability - water move through soil
• Organic matter - pesticides will absorb to
OM
Factors that affect pesticide
movement
Geology
• Distance from the soil surface to the water table
– Spring and fall water table nearest
– Summer: high evapotranspiration rates, less rain
• Permeability of layers
– Gravel and limestone highly permeable
– Clay can be totally impermeable
PROTECTION OF ENDANGERED
SPECIES
• Plant or animal in danger of becoming
extinct
• Endangered Species Act - Federal law
• EPA ensures that endangered species are
protected from pesticides
• SC Endangered Species List
Importance of Protecting
Endangered Species
Maintain biological diversity
• Agriculture - large gene pool allows
development of resistant varieties
• Medicine - natural chemical compounds
– Penicillin
• Interdependence - complex relationship
cannot be predicted
– Predator/prey relationship
South Carolina Endangered
Species
• Most important reason, loss of habitat
• Birds most difficult to protect due to
migratory behavior and large areas of
habitat
Endangered Plants and
Animals
• Red-cockaded woodpecker
• Wood Stork