The ever-magnifying peril of Biomagnification and Bioremediation as its salvation.

  In this so called modern world, due to the ever-increasing use of synthetic and  unwanted substances and introduction of hazardous environmental pollutants to the ecosystem, our mother Earth is tending towards inhabitability slowly but surely.

 The pollutants or the contaminants of the environment generally include Persistent Organic Pollutants (POPs) such as DDT, Polychlorinated Biphenyls (PCBs), Furans, Dioxins, Aldrin, Chlordane, etc. and heavy metals like mercury, lead, arsenic, cadmium, etc. Due to their low water soluble and lipophilic  nature, low digestibility and degradability and their ability to travel long distances, the POPs concentrate in the fat tissues of organisms that consume them i.e. in the food chain which is called Bioaccumulation. These contaminants not only accumulate in a single lower trophic level of organisms but also get transferred across the food chain with increased concentration from lower to higher trophic level. This phenomenon is known as Biomagnification. The ability of such pollutants to bioaccumulate and biomagnify to cause toxicity in the biological systems(i.e. humans, animals, microorganisms and plants) is a serious and important issue of concern that needs immediate addressing for environmental health and safety in the modern world. These pollutants donot emerge themselves from nowhere but are produced in our day to day household and industrial activities.

How does Biomagnification occur?

The initial concentration of these pollutants during their release into the seas, land and air may seem to be very low but eventually when they are consumed and absorbed by lower organisms in the food chains such as fish, earthworms, and plants, they bioaccumulate in their fat tissues and when they are eaten by other organisms of higher trophic levels over the periods of time, they accumulate and Biomagnification occurs. Let me explain with an example: 

Very low concentrations of the toxic chemicals and pollutants are released to the seas. Phytoplanktons - the small plants that float in the seas absorb the toxins and as the toxins donot get broken down or excreted, stay in their tissues. With time, those toxins increase in concentration in the cells. When more and more of these phytoplanktons are eaten by the zooplanktons, the concentrations of these toxins increase in them at a higher rate than the phytoplanktons. Still the toxic effects of the pollutants may not be seen in them. But when they are eaten by the small fishes and the small fishes by the Big fishes, the build up rate of the toxins increases even more. Consequently, when the organisms of the top level like Dolphins, sea birds, and humans consume the large fish, the levels of the concentrations of the toxins are at the highest levels. The toxins may have some serious impacts specially to the top level consumers due to the highest concentration. They can be affected in various ways such as animal's fertility, make them vulnerable to diseases interfering their normal functioning of vital organs, etc.

Causes of Biomagnificatiion:

Obviously all the causes are directly or indirectly related to activities of humans in the environment. Some of the major causes are:

 Agricultural activities: The POPs and heavy metals containing agricultural insecticides, fungicides, herbicides and chemical fertilizers when used haphazardly and indiscriminately, gradually make their way into the environmental bodies like land, water, and air leading to Biomagnification.

 Industrial activities: Every industries when they produce something release byproducts that may contain the pollutants that when released into the environment make their way into the food chains of different terrestrial and aquatic ecosystems causing bioaccumulation and biomagnification.

 

Plastic Pollution: Research shows that plastic contains a harmful chemical called Bisphenol A which is regarded as one of the major contaminant released to water bodies. It not only directly affects the aquatic organisms but also the other terrestrial organisms of the higher trophic levels that consume them. What they say about Karma is indeed true. What we throw into the sea comes to us and harm us through the fishes we eat ultimately.

 Mining operations: The mining operations of certain metals like zinc, copper, lead, cobalt, etc. facilitate the introduction of these mineral deposits to the adjacent environmental systems which get bioaccumulated and biomagnified at various trophic levels.

 Air pollution: Release of toxic gases to the environment via various vehicles and industries are directly and indirectly involved in Biomagnification. Direct way by being directly inhaling and absorbing from air by the plants and animals and indirectly being due to acid rain caused by dissolving of the toxic chemicals in rainwater and entering the food chain via land and water bodies.

 Effects of Biomagnification:

As it is directly related to the ecosystem and every living beings being connected to the ecosystem one or the other way, there is no plant or animal Biomagnification does not have an impact on. The impact however may be major or minor depending upon the concentration of the toxins and even the species of the organisms.

The major effects of Biomagnification can be discussed under the following headings:

 Effect on Human Health: Because of their high degree of toxicity, mercury, cadmium, lead, arsenic and chromium rank among the priority metals that are of public health significance and are considered systemic toxicants that are known to induce multiple organ damage, even at lower levels of exposure. ( Tchounwou et al., 2012). As a result of these and some other pollutant chemicals when consumed by any means, humans are susceptible to cancers, liver and kidney failure, respiratory disorders, birth defects in pregnant women, brain damage, and heart diseases. Excessive exposure to polycyclic aromatic hydrocarbons (PAHs) often results in lung cancer. ( Moorthy et al., 2015) and they are mutagenic, and/or toxic for reproduction ( Crone and Tolstoy, 2010).

 Impact on Aquatic/marine creatures: Reproductive failure in fish-eating birds has been associated with the presence of very high levels of DDT, dieldrin and PCB in many parts of the world.(Portman, 1975). In many cases the failure is attributed to egg-shell thinning of fish-eating birds like brown pelican, sea eagle, etc. causing egg-shell collapse during incubation. Other cases that result from contamination of water bodies with toxic chemicals such as selenium and mercury include damage to the reproduction systems of fish.

 Impact in the Food chains: The process of Biomagnification involves the transfer of toxic chemicals from lower to higher food chains. Due to introduction of such toxins, some groups of organisms may die and disrupt the natural flow of food which may cause a long term effect if not in the short term. 

 Another effect may be the destruction of coral reefs compromising the survival of several other aquatic creatures due to use of cyanide in leaching gold and in fishing.

 Enough about all the causes and effects. As it is said where there's a problem, there's always a solution, some of the remedial measures can be discussed as follows:

-Industries should work on innovative strategies to eliminate mercury and other heavy metal emissions and prohibition and ban policies should be strictly applied to the emission of the toxic substances

-Proper treatment and decontamination of identified polluted areas must be carried out.

-Usage of lead paints and PVC must be reduced or completely avoided if possible to prevent contamination of drinking water.

-Cooking oils, grease, household chemicals, medications, etc. must be disposed properly.

-Arsenic containing chemicals like CCA and ACZA additives to prepare furnitures.

 

Bioremediation, besides all these remedial measures, is found to be more reliable and sustainable to solve the problem of Biomagnification. 

Bioremediation is the process of using biotechnology to degrade hazardous environmental pollutants into non-toxic or less toxic substances especially by utilizing microorganisms like bacteria, fungi, and yeast. Microorganisms contain enzymes that can degrade the environmental pollutants by using them as food and degrade them into less or non toxic forms. As bioremediation can be effective only where environmental conditions permit microbial growth and activity, its application often involves the manipulation of environmental parameters to allow microbial growth and degradation to proceed at a faster rate.(Kumar et al., 2011). The technology is principally based on biodegradation and refers to complete removal of organic toxic pollutants in it to harmless or naturally occuring compounds like carbon dioxide, water, inorganic compounds which are safe for human, animal, plant and aquatic life.(Jain and Bajpai, 2015) Some of the microorganisms used in bioremediation are Penicillium chrysogenum, other species of Penicillium, Aspergillus niger, Gleophyllum striatum, Cyanobacteria, Corynebacterium propinquum, etc. Bioremediation is of two types namely Insitu and exsitu. Insitu bioremediation involves introduction of MO to the area of contamination itself whereas exsitu involves excavation of the pollutants from the area of pollution.

Why go too deep or far to understand the basic concept of bioremediation when the compost which we prepare at our homes, homegarden or agricultural field is also a perfect example of it. 

The impacts of most of the newer man made chemicals are still unknown. God knows what extreme consequences they may bring in the future to the biological systems. Its not enough to discuss the impacts human activities on the environment, what's lacking the understanding how deeply we are connected to the nature. Only when we come to love and respect nature will the planet have any hope of the surviving the current 6th mass extinction i.e. The Holocene/Anthropocene extinction.

 References:

-    Abatenh. E, Gizaw. B, Tsegaye. Z, and Wassie. M. 2017. The Role of Microorganisms in Bioremediation- A Review. Open J Environ Biol 2(1): 038-046.  doi:http://10.17352/ojeb.000007

-  https://www.conserve-energy-future.com/causes-effects-    solutions-    biomagnification.php

-  https://www.eartheclipse.com/ecosystem/causes-effects-     process-of-  biomagnification.html

-    http://www.hawaii.edu/abrp/biordef.html

-   Kumar. A, Bisht. B S, Joshi. V D, Dhewa. T. 2011. Review on Bioremediation of Polluted Environment: A Management Tool. international journal of environmental sciences 1: 1079-1093. Link: https://goo.gl/P6Xeqc

-   Moorthy, Bhagavatula, Chu, Chun, and Carlin, Daniel J. 2015. Polycyclic Aromatic Hydrocarbons: From Metabolism to Lung Cancer. Toxicol Sci., Published online. 145(1): 5–15. doi: http://10.1093/toxsci/kfv040

-    Portmann, J.E. 1975. Ministry of Agriculture, Fisheries and Food, Fisheries Laboratory, Burnham-on-Crouch, Essex. B. 189, 291-304. https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.1975.0058

-   Jain. Pankaj Kumar, and Bajpai. Vivek. 2012. Biotechnology of bioremediation- a review. International journal of environmental sciences 3. 535-549. Link: https://goo.gl/EhLwbz