Pesticides In The Environment

1. Introduction
1.1 Pesticides in the environment
Nowadays, pesticides are widely used in the agriculture sector to enhance crop productivity, minimize pest infestations and manage weeds. According to The United States Environmental Protection Agency, more than half a million tons of pesticide products were used each year in the United States and above three hundred thousands tons of active substances were sold each year in the European Union1. The application of pesticides in the agricultural sector cause some critical environmental issues due to the volatilization, and leaching of pesticides into the surroundings2,3.

One of the negative effects of pesticides on the environment is the potential contamination of surface water and groundwater

This process uses the ability of biological agents, mainly microorganisms, for example fungi, yeast or bacteria can degrade organic contaminants into simple and harmless compounds. Bioremediation is cost effective and more environmentally friendly compared to the conventional methods like thermal, physical and chemical processes4. However, bioremediation usually takes a longer time than conventional methods, because microorganisms need a longer regeneration time and grow slowly. Some of the intermediate steps may produce compounds that are also pollutants, which are sometimes more toxic than the original compound8.

Biodegradation occurs in the environment because of the interactions between species that define the structure of microbial communities and the environmental conditions11. Contaminants in the environment can provide carbon sources and electron donors for certain soil microorganisms, which establish a way for the treatment of pesticide-contaminated sites. Hence, monitoring the microbial community is important in monitoring natural attenuation since they might affect contaminant transformation and are sensitive to environmental

The pesticides are MCPP, bentazon, BAM and 2,4-D. According to Schipper et al. 200832, these pesticides are frequently found in Dutch groundwater and drinking water wells. They belong to different chemical groups with different physical and chemical properties33. For the redox conditions, absence of additional electron acceptor, nitrate reducing, sulfate reducing, and methanogenic conditions were simulated. In these experiments, batch experiment could be easily controlled, which was started with a certain amount of substrate that is continually depleted during the experiments. For column experiment, the groundwater condition was simulated with continual replenishment of substrate and removal of at least some of the metabolic