Drivers of biodiversity loss - II - Pollution

Drivers of biodiversity loss - II - Pollution

The five important drivers of biodiversity loss are

1.Habitat loss and degradation

2.Pollution

3.Invasive species

4.Overexploitation

5.Climate change associated with global warming 

Pollution

Pollutants are the waste products of human society which are dumped into air or water, or onto the land.

The Environmental Protection Agency (EPA) recognizes six major air pollutants: particulates, carbon monoxide, sulfur dioxide, nitrogen dioxide, lead and ozone (ozone is a pollutant in the lower atmosphere).  Air pollution results from the burning of fossil fuels such as oil, gas, and coal. Burning forests and slash-and-burn during agriculture, also produces pollutants. Air pollutants raise global temperature, destroy natural atmospheric processes and cause damage to the environment and human health.

Particulates are solid particles that are light enough to stay suspended in the air.

Ground-level ozone is a pollutant that comes from mixing of fossil-fuel exhaust with sunlight. Ozone slow down plant growth and the plants especially trees become susceptible to invasions by insects. Exposure to ozone may even result in the entire forest ecosystem since the ozone sensitive tress will be replaced by ozone-tolerant species.

Carbon monoxide is a problem where motor vehicle exhaust builds up, as in tunnels. This gas reduces oxygen delivery to organs and tissues and affects vision and motor skills in animals and is poisonous at higher concentrations.

Sulfur oxides inhibit growth of plants. Nitrogen pollutants also injure plants.  Nitrogen and sulfur oxides combine with water in the atmosphere to form acid fog or rain, which destroy an ecosystem.

Acid fog ruins the waxy coatings of leaves, adversely affecting gaseous exchange, undergo slow growth and are prone to injury, more vulnerable to pests or drought. Acid rain also strips off nutrients and metals such as Calcium from soil further harming plant growth. This ultimately affects the other organisms that depend on plant life. Birds and mammals that eat calcium-deficient plants may produce young ones with weak or stunted bones; mammals may produce less milk.

Acidity and run off metals from soil into aquatic bodies adversely affect aquatic organisms too. When a lake becomes so acidic, bacteria cannot survive and thus organic material decomposition will stop.

Sulfur and nitrogen oxides travel hundreds of miles through the atmosphere and create acid rain far away from their source.

Although ground-level ozone is a pollutant, ozone in the upper atmosphere protects life on Earth from some of the Sun’s high-energy ultraviolet radiation (UV).  Chlorofluorocarbons (CFCs) float into the upper atmosphere and release their chlorine ions, which break apart the ozone molecules. Ozone loss allows UV damage in trees and ocean phytoplankton. This results in lower productivity at the base of the food chain which reduce populations of consumers.

As per the Montreal Protocol, there is a worldwide decrease in the use of such chemicals and the rate of increase in the size of the ozone hole is declining.

Oil Leaks and Spills - Marine ecosystems are damaged by oil that spills from shipwrecks or other disasters. For the first day or two after a spill, hydrocarbons evaporate off the oil, killing the larvae and young of nearby aquatic organisms. In the next days and weeks, oil floating at the sea surface reduces the sunlight available for photosynthesis, which causes decrease in primary productivity. Floating oil coat seabird feathers and cause them to lose their buoyancy and insulation and they drown or die. Chemicals released by the oil induce genetic damage and malformations in some species

Nutrients are essential for all living things, but excess nutrients are pollutants. In a natural system, nitrogen is a nutrient when it is fixed or modified by bacteria and algae. Humans fix nitrogen in fertilizers and when fossil fuels are burned. The excess nitrogen and other nutrients when enter freshwater and coastal ecosystems, aquatic plants and algae flourish. When these organisms die, bacteria populations consume the tissue and use up all the water’s oxygen, and without oxygen, fish and other organisms die. This depletion of oxygen in an aquatic system is known as eutrophication.

Pathogens are disease-causing microbes such as bacteria, viruses, fungi, and parasites that infect living organisms. Pathogens may increase their range or their virulence when climatic conditions are abnormal.

Chemicals used as gasoline additives, pesticides, insecticides, solvents, flame retardants, etc are generally toxic. A few chemicals are toxic even in tiny amounts.

Toxic chemicals can lead to physiological and reproductive problems, such as infertility or miscarriage or neurological disorders in animals.

Some toxic chemicals bioaccumulate in the food web and cause problems for consumers. Dichlorodiphenyltrichloroethane (DDT) and Polychlorinated biphenyls (PCBs) are examples.

Heavy Metal is literally a metal with high weight. Iron and aluminum are important components of many rocks, and mercury and lead are present in volcanoes. Burning coal and fuel oils and steel and iron manufacturing releases heavy metals into the air which ultimately reach soil during raining. Eventhough plants and animals require tiny amounts of some heavy metals, all heavy metals are toxic in higher quantities. Mercury, lead, and cadmium are toxic even in tiny amounts.

Many heavy metals bioaccumulate. Mercury in organic form is easily absorbed through the skin, lungs, and guts of animals and is extremely toxic and in humans, organic mercury causes brain, liver, and kidney damage.

Other Pollutants such as sediment washes, Muddy waters, Plastic waste, etc also adversely affect plants and animals.

References

• Emerging Consequences of Biotechnology - Biodiversity Loss and IPR Issues, Krishna Dronamraju, World Scientific Publishing Co. Pte. Ltd.
• Biosphere - Ecosystems and Biodiversity Loss, Dana Desonie, Chelsea House