Match the environmental remedlation method to Its description.
soil vapor extraction
air sparging
bioventing
natural attenuation
Air is bubbled through groundwater to
remove volatile organic pollutants.
Natural processes break down the
pollutants.
Air is circulated through perforated
pipes in the contaminated soil.
Air is pumped into or out of soil to
supply oxygen to microbes.

1. Soil vapor extraction  - 3

2. Air sparging  - 1

3. bioventing  - 4

4. Natural attenuation -2

Explanation:

Soil vapor extraction - Soil vapor extraction (SVE) is the method in which  perforated pipes are used into the soil and air is injected through the pipes. Contamination in soil then removed through perforation in pipes and disposed into an off-gas treatment unit.

Air sparging  - In air sparging process air is injected in bubble form that remediates groundwater by volatilizing contaminants and enhancing biodegradation.

Bioventing  - In bioinventing process low air flow rates are used that provide enough oxygen to sustain microbial activity in the soil and remove other contamination form the soil.

Natural attenuation - Natural attenuation is a natural process of  environmental remediation which reduce the toxicity, mass, or concentration of contaminants in soil without human intervention.

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