Which sampling approach is most appropriate for defining the dissolved contaminant plume in an aquifer?

Which sampling approach is most appropriate for defining the dissolved contaminant plume in an aquifer?

• A. Groundwater sampling to characterize dissolved plumes and aquifer transport
• B. Soil sampling of surface soils only
• C. Air sampling of the vadose zone
• D. Sampling vegetation tissue

Answer: (A)

Defining a dissolved contaminant plume in an aquifer requires measuring contaminant concentrations directly in the groundwater, since the plume consists of dissolved chemicals carried with pore water in the saturated zone. Groundwater sampling using monitoring wells or piezometers provides spatial coverage across the plume, capturing how concentrations vary with distance from the source, depth, and along flow paths, and it reveals the transport properties of the aquifer that shape plume movement. Sampling soil from surface soils would not reveal the dissolved plume within the saturated zone, and would miss how contaminants move through the aquifer. Air sampling of the vadose zone targets contaminants in unsaturated zone air and does not reflect dissolved concentrations in groundwater. Sampling vegetation tissue shows uptake and accumulation rather than the actual dissolved plume in the aquifer. Therefore groundwater sampling is the most appropriate approach to define the dissolved contaminant plume.

Defining a dissolved contaminant plume in an aquifer requires measuring contaminant concentrations directly in the groundwater, since the plume consists of dissolved chemicals carried with pore water in the saturated zone. Groundwater sampling using monitoring wells or piezometers provides spatial coverage across the plume, capturing how concentrations vary with distance from the source, depth, and along flow paths, and it reveals the transport properties of the aquifer that shape plume movement. Sampling soil from surface soils would not reveal the dissolved plume within the saturated zone, and would miss how contaminants move through the aquifer. Air sampling of the vadose zone targets contaminants in unsaturated zone air and does not reflect dissolved concentrations in groundwater. Sampling vegetation tissue shows uptake and accumulation rather than the actual dissolved plume in the aquifer. Therefore groundwater sampling is the most appropriate approach to define the dissolved contaminant plume.