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Published byMildred Garrett Modified over 9 years ago
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The Urban Watershed Unit 1, Topic 1
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1 Urban vs. Suburban vs. Rural
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2 The value of vegetation »Ecosystem services »Oxygen production »Pollution absorption »Natural cooling »Erosion control »Wildlife habitats »Aesthetic value
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3 Heat island effect © censam.mit.edu
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4 Air pollution »Urban areas have higher levels than rural areas, why? »Increased combustion »Industrial processes »Development »Tall buildings »Less vegetation »How could cities reduce local air pollution?
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5 Impervious surfaces and water
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6 Watersheds © NJ Water Supply Association
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7 What is water quality? Assessment based on abiotic and biotic parameters Reflects land use activities and air quality in the watershed Assessment based on abiotic and biotic parameters Reflects land use activities and air quality in the watershed
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8 What can be in the water? Point source pollutants Non-point source pollutants Sewage Industrial waste Oil spills Agricultural waste Sewage Litter Household chemicals Oil and gasoline Industrial particulates Air pollution Pesticides, herbicides, etc… Lawn fertilizers
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9 Land use and water quality
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Abiotic water quality parameters
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11 Dissolved oxygen measure of how much oxygen gas is dissolved in a body of water Measured in parts per million (ppm) 1 ppm = 1 milligram of substance (mg) dissolved in 1 liter (l) of water >6.0 ppm: lots of animals can survive in the water <4.0 ppm: animals begin to stress out, bigger that require more oxygen may begin to die <2.0 ppm: animals cannot survive for more than a short period
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12 Factors that affect DO Oxygen demanding wastes Plant nutrients Turbulence Turbidity Temperature Oxygen demanding wastes Plant nutrients Turbulence Turbidity Temperature
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13 Temperature Varies by season and time of day Affected by surrounding landscape Organisms have temperature tolerance ranges Temperature affects metabolic rates and DO levels Varies by season and time of day Affected by surrounding landscape Organisms have temperature tolerance ranges Temperature affects metabolic rates and DO levels
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14pH measure of the acidity or alkalinity of a liquid pH scale ranges from 0 (most acidic) to 14 (most basic); 7 is completely neutral, pure water (H 2 O) What can extreme pH levels do to proteins? Most organisms have an optimal pH range of 6.5-8
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15 Aquatic acidification Results in decreased biodiversity Sources: Acid deposition Sources: Acid deposition Sulfur based Nitrogen based Sulfur based Nitrogen based Industrial and mining discharge Organic acid from logging and landfills How can acidification be avoided?
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16 Alkalinity Measure of the buffering capacity Carbonate, bicarbonate, hydroxide concentrations limestone Measure of the buffering capacity Carbonate, bicarbonate, hydroxide concentrations limestone
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17 Nitrate (NO 3 - ) Naturally occurring nitrogen- containing nutrient needed by plants Aquatic nitrogen cycle
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18 Phosphate (PO 4 3- ) Naturally occurring phosphorus nutrient needed by plants Usually a limiting factor for plant growth Naturally occurring phosphorus nutrient needed by plants Usually a limiting factor for plant growth
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19 Nitrate and phosphate pollution Human activities add nitrates and phosphates to aquatic systems (cultural eutrophication) These act as fertilizers and result in "blooms" of algae This starts a process that may end in a mass die-off of animal life.
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20 Mass die-off of fish in Narragansett Bay due to anoxia.
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21 Chloride Toxic to freshwater organisms at higher than natural levels Why? (hint: think back to BIO I Honor tonicity lab) How does excess salt get into fresh water bodies? Toxic to freshwater organisms at higher than natural levels Why? (hint: think back to BIO I Honor tonicity lab) How does excess salt get into fresh water bodies?
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22 When is water quality at risk? DO < 5 ppm or mg/L pH < 6.5 Nitrate >1.0 ppm Phosphate > 0.1 ppm Chloride > 1000 ppm (1 ppt…point of reference the ocean averages 34 ppt) DO < 5 ppm or mg/L pH < 6.5 Nitrate >1.0 ppm Phosphate > 0.1 ppm Chloride > 1000 ppm (1 ppt…point of reference the ocean averages 34 ppt)
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