National Core Manual - Chapter Seven Flashcards
Pesticides in the Environment
Solubility
measure of the ability of a pesticide to dissolve in a solvent; usually water
Adsorption
process whereby a pesticide binds to soil particles - attraction between the chemical and soil particles
Persistence
ability of a pesticide to remain present and active in its original form for an extended period before breaking down
Half-Life
description of persistence; comparative measure of the time needed for the chemical to degrade - longer the half-life; more persistent the chemical
Residue
pesticide that remains in the environment after an application or spill
Types of Pesticide Breakdown
chemical degradation, microbial action, photodegradation
Chemical Degradation
breakdown of chemicals that do not involve living organisms, usually by a chemical reaction with water
Microbial Action
breakdown of chemicals by soil microorganisms, such as fungi or bacteria
Photodegradation
breakdown of chemicals in reaction to the sunlight
Volatility
tendency of a pesticide to turn into a gas or vapor; increases as temps and wind increase, more likely in low humidity
Volatility Increase Factors
high temps, high winds, low humidity
Drift
pesticide movement away from the application site by wind or air current
Runoff
pesticide movement in water by surface movement off the treated site
Leaching
pesticide movement by downward flow through the soil
Runoff / Leaching Risk Factors
applying or spilling too much, too much rainwater or irrigation, use of highly soluble or persistent pesticides
Spray Drift
off target movement of a pesticide during a liquid application
Avoiding Spray Drift
pay attention to spray droplet size, wind direction and wind speed
Decreasing Outdoor Drift
spray in winds less than 10 mph, spray downwind from sensitive areas, use proper nozzles and pressure, use drift control additive where possible, lower boom height, leave an untreated buffer area in the downwind target area
Temperature Inversions
can cause extensive drift over long distances, air at ground level is cooler than the air above it - causes sideways air movement and therefore longer drift (often seen in the early evening)
Vapor Drift
the movement of pesticides as gaseous vapors from the target area; volatilization caused by hot weather creating drift
Particle Drift
AKA Dust Drift; the movement of solid particles from the target area in the air during or just after application
Point-Source Pollution
comes from a specific, identifiable location
Nonpoint-Source Pollution
comes from a widespread area
Saturated Zone
the layer of soil, sand, gravel or fractured bedrock in which all available spaces are filled with water
