groundwater contamination

where do aquifers in southern Ontario come from

glaciofluvial deposits (sand, gravel)

where do aquitards in southern Ontario come from

glaciolacustrine deposits (silts and clays)

aquifer types

confined, unconfined

confined aquifer

impermeable layer on the top of the aquifer, no direct vertical connection to the surface (contamination can still occur, just very slow)

unconfined aquifer

no impermeable layer lying on top of the aquifer, direct vertical hydrological connection to surface

water pollution

considered polluted if unusable for a purpose

solutes

dissolved matters

suspended sediments

particulates that are within water bodies (lakes, rivers, etc); can impact water quality and organisms in water

total dissolved solids (TDS)

amount of inorganic and organic particles that are dissolved in water (can be used as an indicator of water quality)

surface runoff

overland flow, dilute solutes

throughflow

soil leachate, medium solutes

groundwater

concentrated solutes

point source pollution

discharged through a discrete identifiable location, easy to evaluate (pipe, ditch, factory smokestack)

non-point source solution

broad diffuse sources, difficult to identify and quantify (cities, farms, roads)

diffuse pollution

Pollution that arises from land activities spread across large areas that have no specific point of discharge (e.g. eutrophication from nitrates); policy issue in the Great Lakes Basin

sources of groundwater contamination

agricultural sewage

agricultural sewage

contamination by untreated agricultural sewage (responsible for walkerton crisis)

walkerton crisis

they relied on groundwater wells which was contaminated by E. coli (shallow aquifer, jointed bedrock, poor treatment)

Ontario greenbelt

provincially protected green space

best types of site for landfill

on thick, fine-grained sediment; no fractures; slow rates of groundwater movement; low permeability; prevent leachate movement

water scarcity

the point at which the total impact of all users affects the quantity or quality of water under prevailing institutional arrangements to the extent that the demand by all sectors cannot be satisfied fully

scarcity

both a social construct and the consequence of altered supply patterns stemming from climate change