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Lecture 4

Lecture 4 - Pollution & Clean Up.pdf

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McMaster University
Earth Sciences
Luc Bernier

PollutionClean Up1 Which BC mining company has recently admitted in Court polluting the Columbia River in Washington State for more than a century a Teck Resources Ltdb Taseko Mines Limited c Barrick Gold Corporation d Thompson Creek Metals Part 1Water Quality StandardsWater Pollution a global problemThis map illustrates the impact of water pollution on rivers shared by two or more countriesRedsevere impactThe problem of water pollution is distributed worldwide and has grown during the 20th centuryThis is attributed to population growth expansion of industry use of fertilizers and pesticides in agricultureWater use has increased six fold and there is more waste in the waterThis is a concern in 15 of the United Nations Environmental program RegionsThe major drainage basins Mississippi river Islands of Caribbean Indian ocean and the coral sea Water Pollution and Health ImpactsWater quality standards have been developed to protect human populations from pollutionThese standards have been developed with a strict focus on medical issuesThey are based on known medical effectsThey relate to drinking water for human consumption without considering the environmental contextThese standards need to be constantly revised in the face of new knowledge PollutionClean Up Water quality standards have not been developed with the protection of wildlife in mindThe effects of water pollutants on wildlife is more poorly understoodThe resistance of one species to a specific pollutant compared to another species varies greatlyThe impact of pollutants on behavior need to be taken into account Water Quality TestingAnother problem relies with the monitoring of water qualityIt is not practical to test water quality on a continuous basisTherefore only spot checks tend to be madeSometimes they are too infrequent to pick up a specific pollution eventCritical peaks of pollution may be missedSampling may be arranged to miss critical peaks in pollution on purposeFor example direct release of sewage into the environment stemming from treatment being bypassed in a wastewater treatment facility are predictableFecal pollution tends to be highest after rain eventsSampling could be devised to miss these days giving the false impression that the water being released meets environmental standards Part 2Agriculture and Water QualityWater Pollution and AgricultureAgriculture is the greatest source of water pollution in developed countriesLargely because of inadequate legislationEnvironmental protection agencies tend to focus on point discharges from industriesFor instance a specific pipe discharging a pollutant in a body of waterPollution from agriculture is harder to pinpoint because its distributed over a larger area eg multiple fieldsIn developing countries water pollution from agriculture has intensifies with the adoption of the practices of green revolution n the 1960s and 1970sFor instance the use of pesticides Nitrates an increasing threatNitrates derived from agricultural fertilizers have been affecting water quality due to a major increase in their use over the last 50 yearsThey now prohibit the phosphorus in certain countries as the fertilizer of choice for instance EnglandWHO limit 45 mgLMuch above the concentrations depicted on this map that illustrates the flow of nitrates in major bodies of water between 19912000The increased levels in major river systems in the world is problematic and leads to additional environmental consequences downstream for instance eutrophication
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