To meet the needs of the rapidly expanding human population, crop production has more than doubled due to the use of pesticides (Gupta S. and Gupta K. 2020). Pesticides used in agriculture might be sprayed on crops, sprayed on the field, injected into the field, or used to treat seeds.
Pesticide application depends on the crop stage, intended target, application technique, weather conditions, and distribution between soils. Since pesticides are deliberately sprayed on the environment to eradicate specific pests, managing them is difficult because they are present wherever there is human habitation. The absence of pesticides and agricultural chemicals may cause a one-third decrease in crop productivity, which would raise the cost of food. Concerns over soil contamination brought on by agricultural and industrial operations have grown recently (Ha et al., 2014).
Many contaminants that find their way into the soil or water provide a serious risk to both human health and the environment. Polycyclic aromatic hydrocarbons (PAHs), petroleum and its derivatives, pesticides, chlorophenols, and heavy metals are the main contaminants found in soil.
The amount of nutrients and minerals absorbed from the soil is reduced by these heavy metals. Pesticide residues are left on agricultural products and make their way into the food chain, where they progressively rise to higher echelons of the food web and endanger both human and animal health. To prevent the buildup of pesticides in the ecosystem and the harm they cause to living things, these practices must be restricted.
The process of the invasion of harmful organic compounds into the food chain is known as biomagnification. In the process of biomagnification, the xenobiotic compound concentration increases multiple times with consumption through food. This process of accumulation of xenobiotic compounds in small concentrations in the body is known as bioaccumulation. After being absorbed into the body, pesticides disrupt the biological processes of the pests and kill the targeted organisms.
Pesticides are sprayed on agricultural land and travel with water, running off to nearby water bodies. This affects the aquatic ecosystem and the animals consuming the water. Pesticides, mainly being organic compounds, are insoluble in water due to their polarity.
Pesticides can enter an animal's body through its food and drink, skin, exoskeleton, or respiratory system. Once pesticides enter the body, they pass through several barriers to reach bodily tissue. Because pesticides are not species-specific and impact other animals as well, they have unintentional environmental consequences.
Inhaling airborne particles or consuming food can also expose humans to pesticides. Due to bioaccumulation, pesticides can linger in the environment for years and pose a health risk. Pesticides in food can lead to a variety of health issues, including cancer, headaches, and endocrine and reproductive system dysfunction. Pesticide exposure is linked to poisoning, cancer, neurological issues, and infertility, according to the Centre for Science and Environment (CSE) (Tongo et al., 2021).
Bioremediation: A Natural Solution to the Environmental Problem
Research interest in the remediation of pesticide- and chlorophenol-contaminated soils is high. The application of bioremediation technology is one of the promising and economical ways to recover contaminated ecosystems. It is a financially viable, environmentally friendly, and sustainable approach. It's a sustainable method that uses biological processes to clean up contaminants by solubilizing or mineralizing them through biochemical processes. Different in-situ and ex-situ techniques are used, depending on specific conditions and concentration restrictions.
The synthesis of "biosurfactants," which are surface-active chemicals derived from microorganisms, is one of the environmentally benign processes mentioned above. A vast range of commercial uses is made possible by the low toxicity, excellent biodegradability, and environmental compatibility of biosurfactants, a broad class of varied substances generated by different microbes.
Microorganisms such as bacteria and fungi use pesticides as a source of carbon and energy. This microbial community is essential, as contaminants are effectively broken down by their combined action. Their deterioration is also influenced by pH, temperature, and organic content. Microbes have the ability to absorb DNA molecules and acquire the biochemical machinery needed to break down pesticides.
One of the natural processes of degradation is phytoremediation, whereby certain plants, such as water hyacinth, sunflower, and willow, hyperaccumulate and degrade heavy metal concentrations in their tissues. Its long-term sustainability and cost-effectiveness make it a crucial step in the biodegradation of heavy metals. Another method, called mycoremediation, uses fungi (white-rot fungi) and enzyme systems to break down organic contaminants like dyes and polycyclic aromatic hydrocarbons.
Despite being a cost-effective and nontoxic process, bioremediation faces various problems, such as a slow mechanism and nutrient availability. In some cases, it is essential to recognize the potential risks associated with the interplay between bioremediation and biomagnification, as intermediate processes like the formation of dichlorodiphenyldichloroethylene (DDE) during the incomplete breakdown of dichlorodiphenyltrichloroethane (DDT) may be more toxic than the original compound.
Recent focus is on genetically modifying these organisms to enhance the efficiency of bioremediation by targeting specific contaminants or operating in harsh conditions. Strains of Pseudomonas and Escherichia coli, when genetically modified, break down oil more efficiently and can metabolize heavy metals like mercury, cadmium, and lead.
Conclusion
The interaction between biomagnification and bioremediation presents ways to manage environmental pollution. However, what is the guarantee that bioremediation, while aiming to eliminate pollutants, does not inadvertently contribute to the very problem it seeks to solve—biomagnification? A deeper understanding and innovative strategies are required for a healthy and sustainable environment.
Bibliography
- Gupta S. and Gupta K. 2020. Bioaccumulation of Pesticides and Its Impact on Biological Systems. Wiley Online Library.
- Ha H., Olson J. R., Bian L., Rogerson P. 2014. Analysis of Heavy Metal Sources in Soil Using Kriging Interpolation on Principal Components. Environmental Science & Technology. Volume 48.
- Prabhat Kumar Srivastava, Vijay Pratap Singh, Anita Singh, Durgesh Kumar Tripathi, Samiksha Singh, Sheo Mohan Prasad, and Devendra Kumar Chauhan. 2020. Pesticides in Crop Production: Physiological and Biochemical Action. John Wiley & Sons Ltd.
- Srivastava, P. K., Singh, V. P., Singh, A., Tripathi, D. K., Singh, S., Prasad, S. M., & Chauhan, D. K. (Eds.). 2020. Pesticides in Crop Production.
- Tongo I., Onokpasa A., Emerure F., Balogun P. T., Enuneku A. A., Erhunmwunse N., Asemota O., Ogbomida E., Ogbeide O., & Ezemonye L. 2021. Levels, Bioaccumulation, and Biomagnification of Pesticide Residues in a Tropical Freshwater Food Web. International Journal of Environmental Science and Technology. Volume 19, Pages 1467–1482.
Authors
Vedant Sonar, Vipul Mahajan (B.Tech Biotechnology-Sem-VII) and Dr. Latika Shendre*, Assistant Professor
Microbial Diversity Research Center,
Dr. D. Y. Patil Biotechnology and Bioinformatics Institute,
Dr. D. Y. Patil Vidyapeeth, Tathawade, Pune - 411033, Maharashtra, India.