ENV100Y5 Lecture Notes - Lecture 43: Experimental Lakes Area, Ozone Depletion, Acid Rain
Module 4: July 3-13
Date: Thursday, July 12
SESSION 46: AIR POLLUTION AND STRATOSPHERIC OZONE DEPLETION (II)
Readings: Chapter 13
Acid Deposition is a Transboundary Pollution Problem
● Acidic deposition = acid or acid-forming pollutants moving from atmosphere to surface
○ Deposition (something deposited) includes both wet and dry fallout (particles)
○ Acid rain = wet deposition of acid
● Primary pollutants originate mainly from burning of fossil fuels
○ Releases sulphur dioxide and nitrogen oxides
○ Reacts with water in the atmosphere to form sulphuric and nitric acids
Sources of Acid Deposition: NOx and SOx
● Primary pollutants mix with water vapour and come out as a form of acidic deposition or
precipitation somewhere else.
History of Acid Rain in Sudbury
● Sudbury once had terrible acid rain
● Mining and refining in Sudbury generated high-SO2 emissions, leading to acid rain
○ 1972: 380-m superstack to disperse emissions - just displaced the problem
○ 1980s: Scrubbers installed to clean emissions (filter pollutants in chimney)
● Acidification and remediation studied at the Experimental Lakes Area* in NW Ontario
○ ELA was shut down by federal government in 2012 (“defunded” by Bill C-38),
after >40 years of critical long-term monitoring studies; saved by Province of
Ontario and International institute for Sustainable Development
Acid Deposition Affects Ecosystems
● Accelerates leaching of base cations (positively charged) from soil
○ Mobilizes Aluminum and other cations, many which are toxic to animals
● Causes accumulation of sulphur and nitrogen in soil
● Hinders plant uptake of water and nutrients
● Causes calcium to leach from needles of red spruce
● Increases tree mortality
● Acidifies lakes; kills fish
● Lowers lakes’ capacity to neutralize further acids
● Elevates aluminium levels in surface waters
● Negatively affects entire food webs
Acid Deposition Has Not Been Reduced as Much as Scientists had Hoped
● New technologies such as scrubbers have been helped
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ENV100Y5 Full Course Notes
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Document Summary
Session 46: air pollution and stratospheric ozone depletion (ii) Acidic deposition = acid or acid-forming pollutants moving from atmosphere to surface. Deposition (something deposited) includes both wet and dry fallout (particles) Acid rain = wet deposition of acid. Primary pollutants originate mainly from burning of fossil fuels. Reacts with water in the atmosphere to form sulphuric and nitric acids. Primary pollutants mix with water vapour and come out as a form of acidic deposition or precipitation somewhere else. Mining and refining in sudbury generated high-so2 emissions, leading to acid rain. 1972: 380-m superstack to disperse emissions - just displaced the problem. 1980s: scrubbers installed to clean emissions (filter pollutants in chimney) Acidification and remediation studied at the experimental lakes area* in nw ontario. Ela was shut down by federal government in 2012 ( defunded by bill c-38), after >40 years of critical long-term monitoring studies; saved by province of. Accelerates leaching of base cations (positively charged) from soil.
