Cultivation of plants each for meals and financial functions has for a very lengthy length been the primary pastime for the human population. The human populace has additionally grown and the dwelling requirements increased, consequently demand for meals has additionally increased. To meet this demands, there is a want for enlargement and intensifying agricultural activities. The use of pesticides has come to be a frequent exercise in most components of the worlds, and in accordance to Wyoming, Department of Agriculture and U.S. Geological Survey, 5.2 billion kilos of pesticides are used global per year. However, alongside with their tremendous mitigation of the pests, there are quite a few issues that have accompanied the use of pesticides and their likely adverse effects on the well-being and the environment. The greatest concern on the use of the pesticide has been the unintended adverse effects through contamination of the Earth’s hydrologic systems. These systems play a vital role in supplying water for both natural ecosystems and mankind. This paper discusses the effects of contamination of these hydrologic systems by pesticides.
According to U.S. Geological Survey (1), about 12 percent of the world’s total land area is under cultivation. This percentage represents 1.5 billion hectares of cultivated land with 277 million hectares under irrigation (U.S. Geological Survey, 1). In irrigation, most of the water used is from surface water storage such as reservoirs, river diversions, and other water distribution systems. However, in some parts of the world, aquifers are an important part of the irrigation system where they provide groundwater. Groundwater irrigates about 100 million hectares (Molden, 4). About half of the U.S. population depend on groundwater for drinking water. Groundwater is located below the surface in spaces within sand, soil, rocks, sediment, and gravel. The groundwater was found to contain pesticides as the soil was found not to prevent pesticides and other chemical compounds from reaching groundwater.
A pesticide is a toxic chemical substance or a mixture of substances that are released into the environment to deter, control, and kill unwanted organisms. All pesticides are commonly used to control insects, weeds, and other organisms in both agricultural and non-agricultural settings throughout the world. These pesticides are chemically designed to be toxic and they have helped significantly increase food production in the world along with several other benefits. However, concerns about the environmental effects of these pesticides have risen and they focus on protecting non-target species in the ecosystem. A new concern has come up in the past decade concerning the effect of pesticide use in groundwater. Water becomes one of the main media through which pesticides from their area of use are transported to other locations in the environment. In the 1970s, traces of aldicarb were discovered in almost 100 wells in Long Island. In California, 2000 wells were found to contain di bromochloropropane (DBCP). More studies led to the discovery of pesticide traces in South Carolina, Arizona, and Maryland in 1980 (Thorburn et al, 49).These discoveries have led to the focus on how to control pests without contaminating the groundwater.
Contamination of ground water by pesticide is now a worldwide issue since groundwater serves an important role in the ecosystems. Groundwater is used as drinking water by a majority of the world’s population. Therefore, an alarm about pesticides contained in groundwater is a critical issue specifically in agricultural zones where most of these pesticides are used and where the population here depend on groundwater for drinking. Groundwater contamination can come from applications to crops, leaching from contaminated surface water, accidental spills and leaks, and improper storage and disposal. It can also occur through runoff from fields after rain, melted snow or irrigation water. Not all pesticides have been found to leach into groundwater, so it is important to understand the chemical-physical properties of a pesticide in order to predict its potential for contaminating groundwater. In the mid-1970s, the soil was thought to filter and prevent infiltration of contaminants into the groundwater. However this was found not be true, and the pesticides dissolved into the groundwater. In addition to the agricultural areas where pesticides infiltrate the ground water, pesticides can be released into the environment through accidental spills and leaks or through improper disposal. Developing countries use only a small proportion of the total world pesticides produced. However, this number has been increasing significantly especially due to the growing economies. Pesticides usage has increased in the cultivation of crops such as maize, wheat, sugarcane, coffee, cocoa, oil palm, bananas, and pineapple. Vegetable application of pesticides is also increasing. In the article by Ghanem (429) a lecturer at Bir Zeit University, Palestine, Subhi working at Palestinian Water Authority, Palestine, Erick a lecturer at Polytech Lille, France and Wasim lecturer at Karlsruhe Institute of Technology, Karlsruhe, Germany, the application rates for pesticides are generally in a range of between 0.2kg/ha to 10 kg/ha.
Contamination of groundwater by a pesticide may take several years depending on the physical, chemical, and biological composition of a contaminant. The contaminant moves within a water aquifer the same manner that ground water moves. Therefore, it is easier to predict that these contaminants move along with ground water flow depending on the topological direction in an area. Soils that are permeable and porous transport certain types of contaminants with ease to aquifers below. Contaminants present in ground water tend to remain concentrated due to the slow movements of ground water. This concentrated area of contaminants is called plume. Ground water along with contaminants are capable of moving through rock fractures, root systems, animal burrows, abandoned wells, and other systems of cracks on the surface. In recent studies in the United States, pesticides and their resultant products have been detected in groundwater. In a research by U.S. Geological Survey (2) at least 143 pesticides and 21 transformation products have been detected in 43 states. These pesticides and their transformation products are present at low concentrations in agricultural areas dissolved in ground water. These traces of pesticides and their transformation products can lead to chronic health complications such as liver and kidney damage, cancer, genetic mutations, and fetal deformation.
Groundwater contamination has several effects including the quality of drinking water becomes poor, there is the possibility of loss of the water supply, degraded surface water systems that get their water from aquifers below, high cleanup costs, and health problems. The pesticides that cause contamination of underground water may also end up being banned from use. The effective use of pesticides while maintaining a good quality of ground water poses a challenge. Water-soluble pesticides enter the ecosystem through dissolution in water and enter groundwater and surface water. These dissolved pesticides end up causing harm to untargeted species in the ecosystem.
Pesticides have a very slow decay rate and, therefore, last very long in groundwater. The pesticides through the groundwater find its way into water bodies with fish and other aquatic animals. Due to their toxic nature, the long period of time they last in water, their high concentration, the fish are exposed to these chemicals and they end up dying. Also due to sub-lethal effects of pesticides, the aquatic animals experience repeated exposure and therefore their survival rate is greatly reduced. The survival rate is reduced as an indirect effect of the pesticides such as they are forced to abandon their nest and brood, their resistance to disease is lowered, body hormones change, and reduced egg production.
Pesticides also help serve an important part in agriculture. Plant diseases, weeds, and other pests cause about 40 percent of agricultural produce to be lost annually (Sailus, 7). Therefore, the use of pesticide leads to a significant increase in crop production and an increased economic profits. Another indirect advantage of the pesticides is that they help keep the food prices under control. Crop production would decline if pesticides would not be put into use. The decline in food production would, in turn, create food shortage that would result in high prices of food commodities.
To ensure the safety of pesticides use, registration of a pesticide before it is released into the market is important. The process of registration involves detection of potential effects on both human and the environment associated with the use of a pesticide. This process ensures the safety of the components used in the manufacturing of the pesticide. To be able to manage the effects of pesticides, registration plays an important role and ensures pesticide product released in the market are authorized and used for their intended purpose.
To protect groundwater, several factors may be considered which determine whether a pesticide will filtrate into ground water. The chemical components of a pesticide need to be studied, the depth of groundwater in areas of application, and good pesticide management practices need to be put into use. Pesticides with a high solubility property need to be handled with care and so are pesticides that do not adsorb rapidly to soil particles, and those that stick in the soil for a long time. Through the Environmental Protection Agency, a list of allowed pesticides needs to be established and pesticides considered to be leechers should also be studied. Farmers can also help reduce contamination of groundwater by applying pesticides to only target areas and avoid water surfaces. They also should follow the storage, use, and disposal of pesticides. In areas with clay soil, the farmers need to avoid a surface runoff.
Contamination of ground water from pesticides has emerged as a key factor in the manufacture, registration, and the use of pesticides. Pesticides that dissolve into groundwater are impossible to clean up and they cause contamination of the water. These pesticides may last in the groundwater for a long period and can move to other areas before they can decay. Therefore, agricultural and non-agricultural use of pesticides faces a challenge on how to control pests without allowing contamination of groundwater with these pesticides. Governmental and non-governmental agencies together with the pesticide users can take actions to help safeguard groundwater from contamination.
Ghanem, Marwan, Subhi Samhan, Erick Carlier, and Wasim Ali. “Groundwater Pollution Due to Pesticides and Heavy Metals in North West Bank.” Journal of Environmental Protection. 2.4 (2011): 429-434. Print.
Molden, David. Water for Food Water for Life: A Comprehensive Assessment of Water Management in Agriculture. London: International Water Management Institute: Earth Scan, 2007. Print.
Sailus, Martin. Pesticides and Groundwater: A Guide for the Pesticide User. Ithaca, N.Y: Northeast Regional Agricultural Engineering Service, Cooperative Extension, 2003. Print.
Thorburn, P J, J S. Biggs, K L. Weier, and B A. Keating. “Nitrate in Groundwaters of Intensive Agricultural Areas in Coastal Northeastern Australia.” Agriculture Ecosystems and Environment. 94.1 (2003): 49-58. Print
U.S. Geological Survey. Pesticides in Ground Water: Current Understanding of Distribution and Major Influences. Sacramento, CA: U.S. Geological Survey, 2006. Print.
Wyoming. Department of Agriculture.; Geological Survey (U.S.). Pesticides in Ground Water: Sheridan County, Wyoming, 1999-2000. Reston, Va.?: U.S. Dept. of the Interior, U.S. Geological Survey, 2001. Print.