Chemical Degradation of Pesticides Using Alkalinity
One bioremediation option is to chemically denature the pesticides by using alkaline water or soil. The carbamates and organophosphates are generally more susceptible to this type of degradation than hydrocarbons or pyrethroids. For the organophosphate Diazinon, a chemical most stable at a pH of 7 with a half-life of 10weeks, a pH 5 will reduce the half-life to 2 weeks.
Microbial Degradation of Pesticides
This is a process usually occurring in the soil whereby the pesticides are broken down into a less active, less toxic compounds by fungi, bacteria and other microorganisms that use the chemical as a food source. There are many soil conditions that strongly influence the effectiveness of the reaction, such as moisture, temperature, aeration, pH, and the amount of organic matter. If the pesticide is applied more to a given area, rapid microbial degradation is more likely to occur as the repeated applications can stimulate a buildup of the microorganisms.
Photodegradation of Pesticides
Pesticides during this process are broken down by sunlight in the air, foliage and soil surface. The intensity of the sunlight highly influences the rate of pesticide break down.
Soil
Inoculation of soil with active organisms can be used to spur bioremediation of contaminated soil. Herbicide degradation tends to occur faster in cultivated soil suggesting the possibility for rhizosphere enhanced phytoremediation.
Atrazine in Groundwater
Atrazine is an s-triazine herbicide that controls weeds by inhibiting photosynthesis and is used on farms all over the world. Atrazine in soil usually breaks down within several months, however once atrazine enters the water supply it is much more recalcitrant. Atrazine has been shown to cause liver, kidney, and heart damage in animal tests, however atrazine’s health effects for humans are still unclear.
Bioremediation for contaminated water supplies has been achieved by adding atrazine metabolizing species to the water supply [Mirgain]. Complete degradation of atrazine requires communities of microorganisms, as no one organism has been found with the ability to metabolize atrazine completely.