Grundvattenplumes

Grundvattenplumes, or groundwater plumes, are zones of groundwater that contain contaminant concentrations significantly higher than the surrounding aquifer. They originate from a localized source such as a leaking storage tank, improper waste disposal, agricultural runoff, or industrial spills, and migrate with the flow of groundwater through the saturated zone.

Movement and spreading are controlled by advection with the groundwater flow, and by dispersion and diffusion that smear the plume. Chemical processes such as sorption to mineral surfaces retard contaminant transport, while degradation and dilution reduce concentrations. The plume's shape and extent depend on the aquifer's heterogeneity, hydraulic conductivity, and redox conditions. Contaminants can be organic solvents, petroleum hydrocarbons, nitrates, or heavy metals. Plumes can be classified as light plumes (LNAPLs) which tend to float at the water table, dense non-aqueous phase liquids (DNAPLs) that sink and form separate phases, or dissolved plumes that are fully mixed in groundwater.

Characterization involves mapping the plume using wells and sensors to measure concentrations and hydraulic parameters. Modelers use this data to predict plume migration and assess remediation options. Monitoring includes installation of monitoring wells, sampling programs, and sometimes tracer tests.

Remediation aims to protect drinking water and ecosystems and may include monitored natural attenuation, pump-and-treat, in-situ chemical oxidation, bioremediation, air sparging, barriers, or combinations. Plumes may persist for years to decades, especially in heterogeneous or low-permeability aquifers. Understanding plume behavior supports risk assessment and land-use planning.