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Unformatted text preview: Water Purification in Nature The natural water cycle purifies water in many ways Chemical Process o Inorganic such as precipitation o Biochemical reactions involving microbes Physical Processes o Dilution (diffusion & dispersion) o Sedimentation o Filtration o Aeration o Figure 15-2 Failure of Natural Purification Processes Increases in human populations & activities often overwhelm natural purification processes Some contaminants arent easily removed by natural filtration or sedimentation o Small particles (like viruses) o Dissolved contaminants Some contaminants are not easily broken down by chemical or biological processes o Synthetic chemicals, including pesticides, PCBs. Industrial solvents o Arsenic, heavy metals, & radionuclides Dilution becomes less effective as the number of pollutant sources increases o Figure 15.07...
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This document was uploaded on 02/01/2011.
- Spring '09