Potentially Harmful Substances are Spread and Concentrated by: Chapter 3.1: Potentially Harmful Substances are Spread and Concentrated by: Air Water & Soil

Transport of Substances in Air Release of the chemical at the source Dispersion of the chemical in the atmosphere (scatter in various directions) Deposition of the chemical in the soil or water

Direction and Distance substances travel in air Determined by: Pollutant properties Wind speed and direction of prevailing winds Usually West to East in Alberta Precipitation Substance will be deposited closer to the source if carried to the ground by rain or snow

Issues: Substances can travel 1000s of Kilometers, and it’s often impossible to find the source Creates conflict when substances cross international boarders

Transport of Substances in Groundwater Water soaks into soil : Near the surface the soil contains both air and water The deeper you go, you find only water = GROUNDWATER The top of the GROUNDWATER zone is the water table where we get our well water

Groundwater Movement Groundwater can travel in all directions, but it travels much slower that rivers and streams Because of slow movement, some contaminants cannot be rid of quickly Can become concentrated over time Creates a problem if we need this water

Factors that can effect Groundwater movement: Connection of pores in soil Too tightly packed = No soil pore connections = extremely slow ground water movement Permeable soil has interconnected pores Pollutants will travel further in Groundwater running through permeable soil Groundwater pollutants occur naturally & as a result of human activity

Transport of Substances in Surface Water Substances can enter Surface water systems by air, groundwater, runoff from agricultural fields, sewage, etc. If substances dissolve they can travel great distances If NOT, they become attached to solids, sink, and become concentrated

They can build up at the bottom of lakes and rivers

Walkerton, Ontario Water supply became contaminated with E. coli bacteria from agricultural runoff into an adjacent well Causing bloody diarrhea, gastrointestinal infections and more With drinking water contaminated: 7 people died and about half the population fell ill (2500)

Transport of Substances in Soil Water hits soil  Moves downward  Dissolves substances in soil  Carries dissolved substances with it (leachate) Once it hits clay, it stops (impermeable) Organic molecules can also absorb chemicals and slow movement Naturally occurring substances can also neutralize chemicals - limestone

Page 242 3.1 Check and Reflect. Exclude question #3.