Define the following Eutrophication

Eutrophication can be best defined as a form of water pollution in which nutrient-rich fertilizers run off along with water and cause excessive algal growth in water bodies. This process results in rapid plant growth in water and depletion of oxygen due to the presence of excessive nutrients in the lake. This causes the death of animals and results in the dysfunction of the ecosystem.

What is biomagnification? Write two effects of biomagnification.

Biomagnification or biological magnification is a gradual increase in the concentration of toxicants at successive trophic levels. This happens because a toxic substance accumulated is not metabolised or excreted by the organism and is passed on to the next higher trophic level. The effects of biomagnification are as follows: Marine life: The various toxic elements get accumulated in the vital organs of the various aquatic creatures, thus affecting their reproduction, development and growth. Human health: Humans become more susceptible to cancers, liver and kidney failure, respiratory disorders, birth defects in pregnant women, brain damage.

Dobson unit is used to measure the thickness or concentration of the ozone layer. It is used to measure the amount of ozone in a vertical column from the ground to the top of the Earth's atmosphere. It is equal to 2.69 10 16 molecules of ozone per square cm.

Define BOD. What is its significance in an aquatic ecosystem?

BOD or biochemical oxygen demand is the amount of dissolved oxygen required for the complete degradation of organic matter in the water by aerobic microorganisms at a particular time and temperature. The main significance of BOD are: It is an indication of organic pollution in the aquatic ecosystem. It can be used as an indicator of the level of environmental pollution. It determines the amount of organic matter present in the water. This affects the aquatic plants and animals in the water body. The greater BOD indicates high pollution. The wastewater treatment plants aim to lower the BOD of water before discharging into the river or other water bodies.

State any four measures to control noise pollution.

Noise pollution is loud disturbing sounds dumped into the ambient atmosphere without caring for the adverse effects it may have. The following are some control measures of noise pollution: Green muffler or Green belt vegetation: It is the rows of trees and shrubs grown and maintain to serve as noise absorbers. It also reduces air pollution by absorbing carbon dioxide and causing the settling of suspended particulate matter. Green muffler or green belt vegetation is specially planted along roads and rails to absorb noise. Earplugs or earmuffs: Traffic police personnel and factory workers exposed to high noise pollution should be provided with earplugs and earmuffs. Decibel metres should be installed at different places in order to monitor the level of noise pollution. Loudspeakers and crackers: The volume of loudspeakers should be kept low. It should not be used beyond the permitted time. There is a permissible sound level and time limit for using crackers during festivals.

List any four effects of global warming.

Global warming is the increase in heat in the atmosphere. This is due to the effect of greenhouse gases that trap heat and do not allow it to escape into space. This has an adverse effect on the environment. Some of them are: Effect on atmosphere: Warming of the troposphere is accompanied by cooling of the upper strata of the atmosphere. Cooling of the stratosphere will tend to increase the size of ozone holes. Effect on weather and climate: Odd climate changes like El Nino become common. Precipitation will increase at higher latitudes both in summer and winter and in southern as well as Western Asia is in summer. Change in sea level: Melting of ice and snow leading to rising ocean levels. This causes submerging of low-lying islands and coastal areas. Effect on the range of species: Rise in temperature of 2-5 0 C will push the temperate range by 250-600 km pole-wards. Many tree species and other plants that are sensitive to temperature will die out.