Groundwater contamination due to pesticide and its impact
Author: Saad, Habel parwaiz, Ayesha Siddique and Iqra
Department of Entomology University of Agriculture Faisalabad
Introduction
The term pesticide include different compound like insecticides, pesticides, herbicides, acaricides, rodenticides, molluscicides, plant growth regulator etc. Organochlorine was one of the most successful insecticide among all those pesticides. It helps in controlling malaria and typhus. It was banned in 1960’s because of their side effect on human beings and animals. Many other pesticides have toxin and hazardous effect on environment.
Ground water pollution is due to leaching of pesticides with water. According to USGS there is 143 different pesticides and 21 transformation products have been found/detected from ground water. These pesticides effecting the beneficial soil fauna and contaminating the fresh water. There is only 1% fresh water is available worldwide. During a survey in Pakistan, when taken sample from hand pumps and wells, 58% of drinking water were found contaminated with organochlorine compound. Many year take to clean water if it get contaminated with toxicity and it may by costly and complex if not impossible (Waskon 1994; o’Neil, 1998; US EPA, 2001). Mainly found chemicals are carbamate insecticides aldicarb and triazine and acetanilide herbicide
According to multi-university research team in Toronto, concludes, “people should reduce their exposure to pesticides”. The result of this study was coherent evidence of health risk
Entry of pesticides into ground water
1. Leaching
Leaching is defined as the movement of pesticides in water through the soil. Leaching take place downward, upward or side way. Leaching can be increase in the following way
· When soil is sandy
· When pesticide is water soluble
· Rain occur shorty after spraying pesticide
· When pesticide is not bond to soil properly
2. Drain flow
The pesticide effecting the water by drainage are soil texture, drainage system, site, weather, application rate, compound properties and season.
3. Spray drift
Spray drift defined as the movement of the spray droplet in air from a treatment site during application
4. Surface runoff
Runoff is defined as the movement of water over a sloping surface. The water carry pesticide dissolving in it. Runoff also take place when water is added to field faster than the absorbing capacity of soil. Pesticide can also runoff when it attach to soil particle.
Threat to marine life
Significant threat to aquatic ecosystem by the contamination of water bodies with pesticides. Pesticides can enter water bodies through diffuse or via point sources. Different pesticide have changed the quality of water that affect the fish and other aquatic organism.
Histophathological effects of pesticides have been studied in fishes. Mainly in liver, blood vessels, kidney, and gills pathological changes occur.
Kennedy et al described the pathological changes of large blood vessels caused by methoxychlor. Boyd found that abortions is cause by sublethal amount of several chorine insecticides.
Persistence of endrin in soil is up to twelve years. Endrin is very toxic to fishes. Sheepshead minnows hatch early when it exposed to high level of eldrin and die on the ninth day of their exposure.
Effect on human health
Ground water pollution is directly associated with human health risk. Many diseases i.e hepatitis, dysentery and poising etc caused by contamination from septic tank waste.
The toxin that have leached into ground water cause poisoning in human. Long term effect such as certain types of cancer may also cause by exposure to polluted water
How to reduce pesticide impact on ground water
Polluted groundwater can be treat or converting them in harmless product by a process called groundwater remediation
1) Implementation of integrated pest management
2) Only use those pesticides that are predetermined crop and pest
3) Considering soil texture and slope while spraying
4) Correcting application rate
5) Calibration of equipment
6) Consideration of weather while applying pesticide
7) Safe disposal of excessive pesticide
8) Prevent drift
9) Reducing chemical control and encourage biological control
List of persistent organic pollutants (pops)
1. Aldrin
2. Chordane
3. DDT
4. Dieldrin
5. Endrin
6. Heptachlor
7. Hexacholobenzene (HCB)
8. Mirex
9. Toxaphene
10. Polychlorinated biphenyls (PCB)
11. Polychlorinated dibenzofurans (PCDF)
12. Polychlorinated dibenzo-p-dioxins (PCDD)
