Scientists observe that iron compounds are able to bind to nutrients in waterways experiencing eutrophication. Which change will most likely occur if iron compounds are added to a lake with an overabundance of nutrients?
Responses-
Fewer microorganisms will grow on the surface of the lake.
More areas of hypoxia will occur in the lake.
More contaminated water will reach the lake.
Less sunlight will reach aquatic plants in the lake
Less sunlight will reach aquatic plants in the lake.
If iron compounds are added to a lake with an overabundance of nutrients, the most likely change that will occur is:
More areas of hypoxia will occur in the lake.
To understand which change will most likely occur if iron compounds are added to a lake with an overabundance of nutrients, we need to understand the process of eutrophication and the role that iron compounds play in it.
Eutrophication is a natural process that occurs when there is an excess of nutrients, such as nitrogen and phosphorous, in a water body, typically caused by human activities like agriculture or sewage runoff. These excess nutrients promote the growth of algae and other aquatic plants, creating algae blooms and dense aquatic vegetation. As these plants die and decompose, bacteria consume oxygen, leading to a decrease in oxygen levels in the water. This decrease in oxygen, known as hypoxia, can be harmful to aquatic organisms.
Iron compounds, such as iron sulfate or iron chloride, can be added to waterways experiencing eutrophication to help mitigate its effects. When iron compounds are added, they act as a binding agent, forming insoluble iron-phosphate complexes. These complexes reduce the availability of phosphates, one of the key nutrients driving eutrophication, thereby limiting the growth of algae and aquatic plants.
With this background knowledge, let's evaluate the given responses:
1. Fewer microorganisms will grow on the surface of the lake: Since iron compounds limit the availability of nutrients, including phosphates, the growth of microorganisms, including algae and cyanobacteria, would likely be reduced. Therefore, this response is plausible.
2. More areas of hypoxia will occur in the lake: Adding iron compounds to the lake can reduce eutrophication and the subsequent decrease in oxygen levels. Therefore, this response seems unlikely.
3. More contaminated water will reach the lake: Iron compounds do not directly affect the inflow of contaminated water into the lake. They primarily target the nutrient concentrations already present in the water body. Therefore, this response is not directly related to the addition of iron compounds.
4. Less sunlight will reach aquatic plants in the lake: If iron compounds effectively reduce the growth of algae and other aquatic plants, less surface coverage of these plants could result in increased sunlight penetration into the water body. Therefore, this response is plausible.
Based on this evaluation, the most likely change that will occur if iron compounds are added to a lake with an overabundance of nutrients is that fewer microorganisms will grow on the surface of the lake and less sunlight will reach aquatic plants in the lake.