Terrestrial life would become impossible with change in atmosphere permitting all solar radiations to reach lithosphere. Solar radiations are essential for food preparation that supports the aquatic life.

Aerosols decrease primary productivity by reducing rate of photosynthesis of autotrophic organisms, which are primary producer of ecosystem of any kind of habitat.

Dichlorodiphenyltrichloroethane (DDT) is chemically an organochlorine that was used an insecticide. It is a stable compound that shows high solubility in the fatty tissues. When it is released in the water via the agricultural field surface run-off, it is ingested by the aquatic organisms like phytoplankton that are main producers in an aquatic food chain. From these, DDT continues rising up the food chain. Because successive consumers at the successive trophic level consume more food, it accumulates at the higher trophic level in greater amounts. This is called biomagnification. Sea/gulls and birds are the top consumers in an aquatic food chain, they will show the highest accumulation.

Hence, the correct answer is 'Sea Gull/Birds '.

Fertilizers added to fresh water increase the nutrients that cause growth of large number of microbes in water that leads to eutrophication.

The concentration of DDT increase with increase in trophic levels. Phytoplankton being producer have minimum concentration of DDT. Human being consume large number of fish so, concentration will be maximum due to biomagnifications.

DDT or dichloro-diphenyl trichloroethane was the first important synthetic pesticide (organo chlorine) discovered in 1939 by a Swiss chemist Paul Muller. It was toxic to wide range of insect pests ("broad spectrum ") yet appeared to have low toxicity to mammals. It was persistent and didn ’t break down rapidly in the environment, so that it didn ’t have to be reapplied often. DDT was so effective at killing pests and thus boosting crop yields and was so inexpensive to make that its use quickly spread over the globe. Farmers used more and more DDT throughout the 1950s and 1960s to get an increased yield of crop,

Bioremediation is a waste management technique that involves the use of organisms to remove or neutralize pollutants. Bioremediation of phenol is carried out using earthworms and bacteria.

Mercury is inert and when swallowed remain non-toxic but becomes severely toxic when inhaled in volatile form. It enters the respiratory system and riches to lungs to cause lung cancer.

Bioremediation method is used to remove oil spill containments in water bodies. In this method large number of bacteria outcompete other organisms for oxygen creating a dead zone.

Global warming due to green house effect melts the glaciers and ice caps that increase the water level of oceans. The countries like Maldives and Bangladesh are in danger of submersion due to increasing ocean water level.

Global warming is caused by green house effect in which temperature of inner atmosphere increases that result into melting of ice caps and glaciers. The melting results into rise in levels of oceans.

Ozone layer in upper atmosphere is being destroyed by chlorofluorocarbon. CFC ’s breaks the molecular  O₃  into  O₂  and O. thus layer of ozone get thinner and not able to prevent UV radiations.

The two main reasons for increase in CO₂ gas are destruction of forest and excessive combustion of fossil fuels. Forests help in decreasing CO₂ gas by photosynthesis process.

Concentration of green house is increasing due to deforestation, increased use of refrigerators and increased combustions of coal and petroleum. Deforestation causes increased level of  CO₂ gas, refrigerators releases CFC ’s gas and burning of fossil fuels also increases carbon dioxide level in atmosphere.

Deforestation generally decreases rainfall. Plants release water vapour in form of water vapour in the process of transpiration. The water vapour contribute in cloud formation to bring rains.