Soil Contamination & Remediation Flashcards

Which soil parameter most directly controls the bioavailability of heavy metals to plants?

Answer: Soil pH

Soil pH is the single most influential factor controlling heavy metal solubility and plant bioavailability, with most metals becoming more soluble and bioavailable under acidic conditions.

Pump-and-treat systems for groundwater contamination are often criticized primarily because:

Answer: Contaminant rebound occurs after pumping ceases

Pump-and-treat systems frequently exhibit contaminant rebound, where concentrations rise back toward original levels when pumping stops, making complete aquifer restoration difficult.

In the context of soil remediation, 'monitored natural attenuation' (MNA) relies on which of the following processes?

Answer: Natural physical, chemical, and biological processes to reduce contaminant concentrations

MNA relies on naturally occurring processes such as biodegradation, dispersion, dilution, sorption, and volatilization to achieve remediation goals without engineered intervention.

What is the primary mechanism by which phytoremediation using hyperaccumulator plants removes metals from soil?

Answer: Plants translocate metals from roots to above-ground biomass which is then harvested

Hyperaccumulators translocate metals from roots through the xylem to shoots and leaves, and the metal-laden biomass is harvested and processed to remove the contaminant.

The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) established which key fund for hazardous waste site cleanup?

Answer: Superfund

CERCLA established the Hazardous Substance Superfund, commonly known as 'Superfund,' to finance cleanup of sites where responsible parties cannot be identified or are unable to pay.

Soil vapor extraction (SVE) is most effective for remediating contaminants with:

Answer: High Henry's Law constant and high vapor pressure

SVE works by drawing air through the unsaturated zone, so it is most effective for volatile contaminants characterized by high vapor pressure and a high Henry's Law constant (tendency to volatilize from water).

Which of the following best describes the 'source zone' in a contaminated site conceptual site model (CSM)?

Answer: The area containing concentrated contaminant mass driving continued plume migration

The source zone is the area where concentrated contaminant mass, such as NAPLs or highly sorbed chemicals, acts as a long-term reservoir that sustains the dissolved-phase plume.