Impacts on Biodiversity

Landfills release pollutants into the soil, water and air, even after site closure. Depending on the pollutants present, it can take anywhere from decades to millennia for landfill stabilization (1). Landfills are environmentally damaging and lead to a loss of biodiversity in two ways:

1. They require clearing wild areas and pollute surrounding habitats through leachates, leading to habitat loss and degradation.

Many old landfills lack liners and proper drainage that prevents leachate from getting into ground water (2). Leachate will occur when surface water, such as rainfall running through waste, extracts toxic solutes with it. Leachate can run along the ground surface far away from the landfill to ponds and lakes damaging the habitat for the organisms that use the water source, as well as poison drinking ground water for human use. Many of the toxins found in leachate come from the improper disposal of household products such as pesticides, solvents, oil, lubricants, and cooling fluids (2), and polystyrene, often found in disposable cups, is also toxic. An experiment done to assess the toxicity of leachate in ground water found increased cancer risk to be the same between leachate from a municipal solid waste landfill and an industrial toxic waste landfill (2).

An example of the effects of landfill leachates on an organism is damage of root tips in plants. In China, it was discovered that leachate concentrations that are often found in areas close to landfills contributed to damage in the roots of the common crop, barley (3). This has important implications for all plants surrounding landfill sites.

 

2. They release landfill gas that contributes to climate change. 

Biodegrading waste produces landfill gas, a mixture of the greenhouse gases carbon dioxide and methane. Landfills comprise the principal source of anthropogenic methane emissions and are estimated to account for 3–19% of anthropogenic methane emissions globally (4). Although the current total rate of methane emission is less than the carbon dioxide emission rate, it is increasing at four times the rate, in part due to landfill emissions (5). Both carbon dioxide and methane trap thermal energy in the atmosphere and cause an increase in temperature at the Earth’s surface and atmosphere. Ultimately, the landfill gas production potential of a landfill is determined by the quality and quantity of waste it holds (5). If we can reduce the amount of waste entering landfills, we can reduce landfill gas emissions and slow climate change.

Due to the global nature of climate change, landfill gases released from local landfills have the ability to affect the biodiversity on the other side of the world. The global impact of climate change on biodiversity is enormous. However, due to the great diversity of organisms on the earth, it is hard to predict exactly how ecosystems, communities and individual species will respond to rising temperatures, precipitation and sea levels. What we do know is that during warming episodes, extinction of species, changes in the composition of communities and a reduction of species richness can occur (6). Species’ will be pushed out of their thermal tolerance ranges, forced to vacate degrading habitats and subjected to intense weather events.

An example of the effects of climate change on biodiversity is the destruction of the coral reefs. Coral reefs cover an area of over 280,000 kmand support thousands of marine species (7). They also protect shores from the impacts of waves and storms, and provide benefits to humans in the form of food and medicine (7). Coral reefs are being subjected to coral bleaching, meaning organisms that provide nutrients to coral ecosystems are being destroyed because of a reduction in photosynthetic pigments caused by increasing temperatures (8). If, and when, coral reefs are completely destroyed, they will take with them about one-third of the world’s marine biodiversity (9). When this occurs, a domino effect will cause changes in other ecosystems and the impacts will be far reaching (9).

But why should we care about biodiversity?

There are many reasons why biodiversity is important. For one, we are a part of biodiversity; the same things that affect other organisms, such as water and air quality, have the ability to affect us as well. Not only that, but we enjoy the benefits of its services, such oxygen production by plants and pollination of crops by insects. It is estimated that of the 300 commercial crops, 84% are  insect pollinated, and insects are responsible for 80–85% of all pollinated commercial hectares (10). Estimated replacement of these services is estimated to be in the hundreds of millions each year (10). Additionally, we require biodiversity for resource exploitation, such as food, construction materials and medicine. Of the 150 most prescribed drugs in the US, 115 are derived from plants (11). Thousands of undiscovered plants that may hold potential medicinal properties may soon face extinction. In fact, a huge number of species present on our planet today may go extinct before we even get a chance to discover them.

(1)  Lisk, D.J. (1991) Environmental effects of landfills. The Science of the Total Environment 100: 415-468.
(2) Schrab, G.E., Brown, K.W., and K.C. Donnelly. 1993. Acute and genetic toxicity of municipal landfill leachate. Water, Air, and Soil Pollution 69: 99-112.
(3) Sang, N. and G. Li. (2006) Municipal landfill induces cytogenic damage in root tips of Hordeum vulgare. Ecotoxicology Environmental Safety. 63(3):469-473.
(4) Park, J-W. and H-C. Shin. (2001) Surface emission of landfill gas from solid waste landfill. Atmospheric Environment 35(20): 3445-3451.
(5) Gardner, N., B.J.W. Manely and J.M. Pearson. (1993) Gas emissions from landfills and their contributions to global warming. Applied Energy 44: 165-174.
(6) Barnosky, B.D., E.A. Hadley and C.J. Bell. (2003) Mammalian response to global warming on varied temporal scales. Journal of Mammology 84(2): 354-368.
(7) Coral Reefs: Ecosystems of Environmental and Human Value. Global Issues. (Accessed March 23rd, 2012):<http://www.globalissues.org/article/173/coral-reefs&gt;
(8) Coral Reef Bleaching. Odyssey Expeditions. (Accessed March 23rd, 2012): <http://www.marinebiology.org/coralbleaching.htm&gt;
(9) Climate Change Affects Biodiversity. Global Issues. (Accessed March 23rd, 2012): <http://www.globalissues.org/article/172/climate-change-affects-biodiversity&gt;
(10) Allsopp, M.H., W.J. de Lange and R. Veldtman. (2008) Valuing insect pollination services with cost of replacement. Plos One 3(9).
(11) What is biodiversity and why should we care? Crex Group. (Accessed March 24th):<http://crexgroup.blogspot.ca/2011/09/biodiversity-what-is-it-and-why-should.html&gt;

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