Question

a vacant lot in a neighborhood is planned to be developed into a community garden. the soil on this site has a layer of mercury - contaminated soil to a depth of 20 centimeters, which is toxic to humans and wildlife. the mercury must be reduced to safe levels before development can occur. three methods for removing mercury from the soil are described in the table below.

method description
removing the soil dig up the contaminated soil. transport it to a hazardous waste landfill.
washing the soil dig up the contaminated soil. wash the soil on - site with a water solution to remove the mercury. capture the solution containing the mercury compounds, treat it, and return the treated soil to the ground.
phytoremediation grow specific plants that absorb mercury from the contaminated soil. harvest the plants and safely dispose of the plant material. repeat several cycles until the mercury levels are reduced.

all of the treatment methods described will successfully reduce mercury to safe levels. each method has environmental advantages and disadvantages.

question: which human activity represents an advantage to using phytoremediation as a way to reduce the amount of mercury in the soil before developing the land? (use the information provided to help you answer the question.)
a) transporting the contaminated soil to a landfill, which can harm other ecosystems
b) using plants to absorb mercury, which reduces the need for transporting hazardous waste
c) applying chemicals to the soil, which can produce toxic runoff
d) ignoring the contamination

Explanation:

Phytoremediation uses plants to absorb mercury. This reduces the need for transporting hazardous waste, which is an advantage compared to other methods like removing the soil. Options A and C describe disadvantages of other methods, and D is not a valid solution method.

Answer:

B. Using plants to absorb mercury, which reduces the need for transporting hazardous waste