Lecture 9a - Geophysics for groundwater pollution

Flashcards on geophysical methods for waste management and groundwater protection, covering topics such as contaminated land, pollution sources, and geophysical techniques.

What is contaminated groundwater or land?

Water or land containing substances harmful to people or the environment, usually chemicals from human activity.

What is the most effective way to carry out mitigation?

To treat the source of the problem, not just the effect.

Why are geophysical techniques widely used for assessing groundwater and groundwater pollution issues?

They can investigate the subsurface efficiently with minimum disturbance, and many are sensitive to fluid-based properties.

What is an example of a broad or diffuse source of groundwater pollution?

Agricultural use of fertilizers and pesticides.

What is an example of a localized or point source of pollution?

Petrochemical spills or long-lived undetected leaks.

What is the groundwater forum?

A valuable resource for general information on groundwater and the threats to it in the UK.

Why is it important to protect groundwater quality?

To ensure high-quality groundwater and minimize the need for extensive treatment.

What does LNAPL stand for, and what is its density relative to water?

Light Non-Aqueous Phase Liquid, less dense than water.

What does DNAPL stand for, and what is its density relative to water?

Dense Non-Aqueous Phase Liquid, more dense than water.

What happens when LNAPL reaches the water table?

It ponds at the top of the water table.

What happens when DNAPL reaches the water table?

It continues to descend into the saturated ground below the water table.

What is the potential of using geophysical techniques to distinguish between pollution plumes and the surrounding saturated ground?

To map plume locations and forecast their future dispersion.

What information are we trying to determine at contaminated sites?

Identifying leaks or spills, their location, timescales, and effects.

What is the first task when dealing with abandoned or covered-over sites?

To determine the location of potential sources.

How can geophysical methods contribute to protecting groundwater resources?

Through their capabilities for characterizing subsurface properties related to hydrogeology and fluids, and assessing physical properties of aquifers.

What are the initial aims of geophysical investigations?

To map variations in groundwater quality and detect potential contaminants.

Why are boreholes valuable in geophysical investigations?

They provide valuable locations for direct subsurface measurements and sampling.

What is GIS and what's its role?

A geographical information system - an effective way to visualize different types and styles of data.

Which geophysical methods are dominantly used for water-focused investigations?

Electrical and electromagnetic methods, including GPR.

Why is seismic data particularly valuable?

They provide a strongly independent observation set for validation and verification.