Groundwater Quality

Introduction and Overview

Jenny Webster-Brown

UNESCO 2000

Natural Resources Canada. http://geoscape.nrcan.gc.ca/h2o/okanagan

Unsaturated zone

Unconfined aquifer

Confined aquifer

Well 1Well 2

River

Unconfined aquifer

Confined aquifer

River

Groundwater Quality

Function of:

• Host rock composition (high water:rock ratio)

• Depth and age

• Composition of recharge & infiltration from unsaturated zone1

• “Mobility” of particular chemicals2

1. Problem contaminants include:

– Soluble ions and metals (e.g., nitrate, boron, zinc and arsenic in absence of oxygen)

– Microorganisms from sewage

– Soluble organic substances

2. Depends on ability to adsorb onto mineral surfaces, which retards access to, and movement in, groundwater

Contaminants with more limited mobility include:

– lead – phosphate– arsenic in presence of oxygen

1850 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990

Emergence of water quality problems related to human activity