Topic_14___Human_Impacts_Freshwater

Topic_14___Human_Impacts_Freshwater - Topic 14: Human...

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Unformatted text preview: Topic 14: Human impacts on the Hydrosphere Part I: Freshwater Lecture Outline I. Major Impact Issues: A. Types of impact of human activities: Water quality, quantity, sources B. Case studies: The American Southwest; The Edwards aquifer II. Solutions and Alternatives A. Conservation B. Water quality protection C. Increase supply D. Alternatives to solutions: New World Water? I. Major impact issues: Perturbation of biogeochemical cycles and the hydrologic cycle and sustainability of water resources The glass is half empty: The number of people without access to safe drinking water will jump from 1.4 billion today to 2.3 billion in 2025 unless governments step up action to address the problem. "Conflicts over water, both international and civil wars, threaten to become a key part of the 21 st century landscape."- Hans van Ginkel, rector of the UN University. (World Watch Institute) "Nine planets around the sun, only one does the sun embrace. Upon this watered one, so much we take for granted" - One Sweet World , Dave Matthews Band. A. Types of impact of human activities on aquatic environments 1. Water quality a. change in salinity - example: Colorado River ( Cadillac Desert ) b. increase in toxins: Human health and ecosystem health 1. organic chemicals - examples: Electronics insulation: PCBs and a Fish Advisory Pesticides: DDT dioxin: not a big problem dioxin: a nightmare Solvents: trichloroethylene Vehicle emissions and parking lot sealants: PAH's 2. inorganic chemicals: metals - examples: Mercury Lead Chromium-6 c. change in nutrient balance - example: eutrophication; example of Barton Creek d. poor sanitation - 25% of developing world remains without clean water and 66% lacks sanitation. Water borne diarrheal diseases, caused by poor water and waste management are the worlds leading cause of illness and the cause of 5 million deaths among children, most of whom come from poor urban families (Brown et al., World Watch Institute, 1999). 2. Water quantity a. Diversion, damming of flow Examples: Colorado River Aral Sea: Compare NASA space shuttle photos from 1985 & 1998 b. Over-withdrawal - examples: Mexico City subsidence of 1 ft/yr; Comanche Springs, TX; Ogalalla aquifer, north Texas 3. Sources of impacts on water quality/quantity a. By type of activity 1. Industrial - 30 % of total water use. How much water does it take to make a car? 2. Agricultural, livestock 65% of total use 3. Residential - < 10% of total use b. Point source vs. non-point source pollution c. By countries of the world. Guess how we, the U.S., stack up. Making waste Withdrawing water Use of pesticides & fertilizer (EPA) U.S. Annual Pounds of Pesticide Active Ingredient By Pesticide Type, 1980 - 1999 Industry/Commercial/Government Market Sector Guess how we, Texas, stack up.Guess how we, Texas, stack up....
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Topic_14___Human_Impacts_Freshwater - Topic 14: Human...

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