Water Quality and Pollution

Trees planted along sewage system to absorb waste water.

Water containing pollutants is termed wastewater, which requires treatment before safe discharge or reuse. Pure water is free of contaminants, potable water is safe for drinking, and salty water refers to high mineral content - none of these describe pollutant-containing water.

Metals are the inorganic impurity in the waste water.

Nitrogen and phosphorus are inorganic Impurities in the sewage water.

Fruit and vegetable waste is an organic impurity present in waste water.

Hydroponics is a cultivation method where plants grow in nutrient-rich water solutions instead of soil. The term is derived from 'hydro' (water) and 'ponos' (labor). It allows precise control over nutrients and is used in commercial greenhouses.

Yes, temperature changes the state of water. E.g. If we boil the water at high temperature, water changes in to vapours and like wise if we freeze water at very low temperature, water changes in to ice, which is solid.

1. Nutrients leaching from agricultural land into water courses, can lead to algal blooms and eutrophication. An algal bloom is a rapid increase or accumulation in the population of algae (typically microscopic) in an aquatic system. Eutrophication is the ecosystem response to the addition of artificial or natural substances, such as nitrates and phosphates, through fertilizers or sewage to an aquatic system.
   1. The Nationwide Urban Runoff Program (NURP) is a research project conducted by the US Environmental Protection Agency (EPA) between 1979 and 1983. It was the first comprehensive study of urban stormwater pollution across the United States.

Reason: The practice of growing four to five fish species in a single fish pond is known as composite fish culture. In such systems, these species are selected so that there does not exist any competition for food among them as they possess different types of food habits. E.g. catlas are surface feeders, rohus feed in the middle zone of the pond, mrigals and common carps are bottom feeders and grass carps feed on the weeds. These species when together can use all the food in the pond without competing with one another. This increases the fish yield from the pond. Thus option (C) and (D) are incorrect as both are advantages of composite fish culture. One problem with such composite fish culture is that many of these fish breed only during monsoon. Even if fish seed is collected from the wild, it can be mixed with that of other species as well. So, a major problem in fish farming is the lack of availability of good quality seed (i.e. option B). To overcome this problem, ways have been worked out to breed these fishes in ponds using hormonal stimulation. This has ensured the supply of pure fish seed with desired quantities. Weeds are the unwanted plants which compete for nutrients with the main crop. So, option (A) is incorrect with respect to the disadvantage of composite fish culture. 

Eutrophication is the ecosystem response to the addition of artificial or natural substances, such as nitrates and phosphates to an aquatic system.

Biological oxygen demand (BOD) is the amount of oxygen consumed by microbes to decompose organic matter. It is least in pure water.

Due to eutrophication, biological oxygen demand increases.

Phosphorus causes uncontrolled growth of aquatic plants and bloom forming algae in natural waters.

Amoeba is generally seen in stagnant water.

When a freshwater plant is transferred to marine water, it dies due to exosmosis.