Correct Option (D)
The analogy of wetlands as the "kidneys of the Earth" highlights their crucial role infiltering and purifying water. Similar to how kidneys remove waste products and excess substances from the blood, wetlands perform a vital function incleansing water bodies. Aquatic plants within wetland ecosystems are particularly effective inabsorbing various pollutants, including heavy metals and excess nutrients such as nitrogen and phosphorus, from the water. This natural process ofabsorption and sequestrationeffectively detoxifies and purifies the water, directly reflecting the filtering and cleansing function implied by the "kidney" metaphor.
Incorrect Options
Option 1: The water cycle in wetlands involves surface runoff, subsoil percolation and evaporation.
This statement describes the hydrological processes that occur within wetlands and their contribution to the broader water cycle. While wetlands are integral to water cycling, this function does not specifically represent the "kidney-like" role of filtering and purifying water from pollutants, which is the essence of the given analogy.
Option 2: Algae form the nutrient base upon which fish, crustaceans, molluscs, birds, reptiles and mammals thrive.
This option describes the ecological role of algae as primary producers, forming the base of the food web and supporting a diverse range of aquatic and terrestrial life in wetlands. It pertains to trophic relationships and biodiversity rather than the specific function of filtering or removing pollutants and excess nutrients from water, which is implied by the "kidneys of the Earth" analogy.
Option 3: Wetlands play a vital role in maintaining sedimentation balance and soil stabilization.
Wetlands do contribute significantly to sedimentation control by trapping sediments and to soil stabilization, thereby preventing erosion and maintaining the physical integrity of shorelines and riverbanks. However, this function primarily relates to physical processes of sediment retention and structural support. While important, it does not directly align with the "kidney-like" function of chemical filtration and detoxification of water from dissolved pollutants and excess nutrients as directly as the absorption by aquatic plants.