Question

Which of the following would be considered an example of bioremediation?

(A) adding nitrogen-fixing microorganisms to a degraded ecosystem to increase nitrogen availability

(B) using a bulldozer to regrade a strip mine

(C) reconfiguring the channel of a river

(D) adding seeds of a chromium-accumulating plant to soil contaminated by chromium

Short answer

(A) The option ‘Adding nitrogen-fixing microorganisms to a degraded ecosystem to increase nitrogen availability’ is false.

(B) The option ‘using a bulldozer to regrade a strip mine’ is false.

(C) The option ‘reconfiguring the channel of a river’ is false.

(D) The option ‘adding seeds of a chromium-accumulating plant to soil contaminated by chromium’ is true.

Step-by-step solution

Bioremediation

Bioremediation is a branch of biotechnology that focuses on restoring the soil and removing all polluted pollutants with the help of biological organisms. Microbes, such as bacteria and multi-cellular bryophytes, can be used for bioremediation.

It is an eco-friendly method for improvising the conditions of the degraded environment.

Explanation of option (A)

The addition of nitrogen-fixing microbes to any ecosystem that has been degraded due to disturbances cannot be considered bioremediation. It will enhance the nutrient level of the soil but will not remove polluting agents.

Thus, this statement does not describe a mechanism of bioremediation.

Therefore, the given option is false.

Explanation of option (B)

The usage of bulldozers for regrading a strip mine only refers to the slight restoration of the geographic condition of the mined area. It is not bioremediation as mining does not involve ecosystem degradation due to increased pollution, and its restoration is also not related to managing pollutants.

Thus, the recovery of mining sites through bulldozers is not a bioremediation technique.

Therefore, the given option is false.

Explanation of option (C)

The natural flow of water is managed to gain the most benefits from rivers, notably for hydroelectricity generation. This results in the destruction of the ecosystem linked with that river.

Ecologists restore the natural path of the river with the aim of ecological restoration.

Thus, the statement exemplifies ecological restoration.

Therefore, the given option is false.

Explanation of option (D)

Proper growth of plants requires a proportionate supply of both macro and micronutrients, which are obtained from the soil. If the nutrient concentration exceeds the optimal level, it becomes toxic.

The plan of depleting the chromium levels by adding seeds of a plant that accumulates chromium is bioremediation.

Thus, this statement accurately describes an example of bioremediation.

Therefore, the given option is true.