[Mission 2023] STATIC QUIZ, 29 October 2022 – Environment

Solution: b)

Biomagnification
Biomagnification refers to the tendency of pollutants to concentrate as they move from one trophic level to the next.
Thus in biomagnification there is an increase in concentration of a pollutant from one link in a food chain to another.
In order for biomagnification to occur, the pollutant must be: long-lived, mobile, soluble in fats, biologically active. If a pollutant is short-lived, it will be broken down before it can become dangerous.
If it is not mobile, it will stay in one place and is unlikely to be taken up by organisms. If the pollutant is soluble in water, it will be excreted by the organism. Pollutants that dissolve in fats, however, may be retained for a long time.

Solution: a)

The higher amounts of waste increases the rates of decomposition and O2 consumption, thereby decreases the DO content of water. The demand for O2 is directly related to increasing input of organic wastes and is expressed as biological oxygen demand (BOD) of water.

Water pollution by organic wastes is measured in terms of Biochemical Oxygen Demand (BOD). BOD is the amount of dissolved oxygen needed by bacteria in decomposing the organic wastes present in water. It is expressed in milligrams of oxygen per litre of water.

The higher value of BOD indicates low DO content of water. Since BOD is limited to biodegradable materials only. Therefore, it is not a reliable method of measuring pollution load in water.

Chemical oxygen demand (COD) is a slightly better mode used to measure pollution load in water.

It is the measure of oxygen equivalent of the requirement of oxidation of total organic matter (i.e. biodegradable and non-biodegradable) present in water.

Solution: c)

The London Convention: Its objective is to promote the effective control of all sources of marine pollution and to take all practicable steps to prevent pollution of the sea by dumping of wastes and other matter.

Solution: b)

Dissolved oxygen:
In aquatic ecosystems oxygen is dissolved in water, where its concentration varies constantly depending on factors that influence the input and output of oxygen in water.
In fresh water the average concentration of dissolved oxygen is 0.0010 per cent (also expressed as 10 parts per million or 10 ppm) by weight, which is 150 times lower than the concentration of oxygen in an equivalent volume of air.
Oxygen enters the aquatic ecosystem through the air water interface and by the photosynthetic activities of aquatic plants.
Therefore, the quantity of dissolved oxygen present in an ecosystem depends on the rate at which the aforesaid two processes occur.
Dissolved oxygen escapes the water body through airwater interface and through respiration of organisms (fish, decomposers, zooplanktons, etc).
The amount of dissolved oxygen retained in water is also influenced by temperature. Oxygen is less soluble in warm water. Warm water also enhances decomposer activity. Therefore, increasing the temperature of a waterbody increases the rate at which oxygen is depleted from water.
When the dissolved oxygen level falls below 3-5 ppm, many aquatic organisms are likely to die.

Solution: c)

In situ bioremediation techniques
It involves treatment of the contaminated material at the site.
Bioventing – supply of air and nutrients through wells to contaminated soil to stimulate the growth of indigenous bacteria. It is used for simple hydrocarbons and can be used where the contamination is deep under the surface.
Biosparging – Injection of air under pressure below the water table to increase groundwater oxygen concentrations and enhance the rate of biological degradation of contaminants by naturally occurring bacteria
Bioaugmentation – Microorganisms are imported to a contaminated site to enhance degradation process.

Solution: d)

“Biodiversity Heritage Sites” (BHS) are well defined areas that are unique, ecologically fragile ecosystems – terrestrial, coastal and inland waters and, marine  having rich biodiversity comprising of any one or more of the following components: richness of wild as well as domesticated species or intra-specific categories, high endemism, presence of rare and threatened species, keystone species, species of evolutionary significance, wild ancestors of domestic/ cultivated species or their varieties, past pre-eminence of biological components represented by fossil beds and having significant cultural, ethical or aesthetic values and are important for the maintenance of cultural diversity, with or without a long history of human association with them.