Chapter 11 Water Resources and Pollution Notes PDF

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Chapter 11 Water: Resources and Pollution Notes

1. Water Resources 1. Water 1. dissolves nutrients and distributes them to cells 2. regulates body temperature 3. supports cells 4. removes waste products 5. accounts for 60% of human body 2. Hydrologic Cycle 1. Solar energy constantly evaporates water 1. evaporated water condenses to liquid (rain, fog) or solid snow/ice when it cools 1. Precipitation- general term for falling liquid or solid water 1. most water precipitates somewhere distant from where it evaporated 2. Transpiration 1. evaporation of water from plant surfaces, especially through stomates 3. Evapotranspiration 1. combined processes of evaporation and transpiration 1. both processes more active in hot climates due to more solar energy 3. Residence Time 1. Residence Time 1. length of time a component (ie individual water molecule) spends in a certain compartment/location before moving on through certain process/cycle 1. avg. water molecule stays in the ocean for about 3000 years before it evaporates and starts through hydrologic cycle again 1. stays in atmosphere only about a week 2. Nearly all world's water is in oceans 1. crucial role in moderating earth's temp. 2. over 90% world's living biomass is contained in the oceans 3. Glaciers, ice caps and perennial snowfields contain nearly 90% world's fresh water 4. Climate change threatens these resources 4. Groundwater Storage Vast/Cycles Slowly 1. Soil moisture (soil water) in the top meter or less provides moisture for most plants 2. Water Table 1. top layer of zone of saturation 2. undulates according to surface topography and subsurface structure 3. Zone of Aeration 1. upper soil layers that hold air and water 4. Zone of Saturation 1. lower soil layers where all spaces are filled w/ water 5. Aquifers 1. porous water bearing layers of sand, gravel and rock below earth's surface 2. reservoirs for groundwater 3. below Aquifers relatively impermeable layers of rock/clay keep water from seeping out 1. instead water seeps horizontally through porous layer 1. known as artesian wells/springs 6. Recharge Zones

1. areas where surface water filters into an aquifer 5. Surface Water/Atmospheric Moisture 1. Rivers contain small amount of water at any one time 1. would dry up if not constantly replenished 2. size compared in terms of Discharge 1. amount of water that passes a fixed point in given amount of time 2. expressed as liters/cubic feet of water per second 2. Lakes-nearly 100 times as much water as all rivers/streams combined 3. Wetlands 1. bogs, swamps, wet meadows and marshes 2. play vital role in hydrologic cycle 3. lush plant growth stabilizes soil and holds back surface runoff 1. allows time for infiltration into aquifers and producing even, year long stream flow 4. atmosphere contains only 0.001% total water supply 1. most important mechanism for water redistribution worldwide 2. Water Use 1. Worldwide agriculture consumes ~75% water resources 1. Industry consumes another 20% 2. Domestic Use 5% 2. Virtual Water 1. Evaluating water consumption tricky due to variety of forms of exporting it 3. Industrial Uses 1. includes energy production 4. Domestic Use 1. ppl in developed countries consume ~10 times more water every day than those in developing nations 2. at least a billion ppl lack access to safe drinking water 1. 2.5 billion don't have adequate sanitation 3. Rural ppl often have less access to good water than city dwellers 3. Water Scarcity 1. ~1/3 world population lives in countries where water supplies don't meet everyon'e minimum essential water needs 1. withdrawl expected to continue to grow as more land is irrigated to feed expanding population 2. Groundwater Supplies 1. Groundwater 1. provides ~40% of fresh water for agricultural/domestic use in U.S 2. Subsidence 1. settling of ground surface caused by collapse of porous formations that result from withdrawal of large amounts of groundwater, oil, or other underground materials 3. Diversion Projects 1. > ½ world's 227 largest rivers have been dammed/diverted 1. of the 50000 largest dams, ~ ½ in China 1. justified in terms of flood control, water storage and electricity production 2. Costs 1. villages relocated 2. fertile farmlands/fishing grounds flooded

3. evaporation reduces water resources 4. regions downstream may be deprived of water altogether 1. leads to over pumping of groundwater, farm failures and economic strain 4. Water Conservation/Management 1. Healthy forests especially important for water conservation 1. protect moisture/keep sediment from clogging streams 5. Water Pollutants 1. any physical, biological, chem. change in water quality that adversely affects living organisms or makes water unsuitable for desired use is pollution 1. natural sources of water contamination like oil seeps or sedimentation from erosion 2. Pollution Point/NonPoint Sources 1. Pollution control standards and regulations usually distinguish point/nonpoint pollution sources 2. Factories, power plants, sewage treatment plants, underground coal mines and oil wells classified as point sources 1. discharge pollution from specific locations 1. I.e drainpipes, ditches and sewer outfalls 2. sources discrete and identifiable and relatively easy to monitor/regulate 3. Nonpoint sources are diffuse w/ no specific location where they discharge into certain body of water 1. harder to monitor/regulate 2. origins hard to identify 3. sources include runoff from farm fields/feedlots, golf courses, lawns/gardens, construction sites, logging areas, roads, streets and parking lots 4. often highly episodic 3. Biological Pollution 1. most serious water pollutants in terms of human health are pathogenic (disease causing) organisms 1. ex. typhoid, cholera, bacterial/amoebic dysentery, enteritis, polio, infectious hepatitis, schistosomiasis 2. main source of these pathogens is untreated/improperly treated human wastes as well as animal wastes from feedlots/fields near waterways/ food processioning factories w/ inadequate waste treatment facilities 3. Coliform Bacteria 1. detecting specific pathogens in water is hard, time consuming and costly 1. water quality described in terms of Coliform Bacteria 2. Any of the many types of bacteria living in the colon/intestines of humans or other animals 1. most common E. coli 3. If ANY are present in a water sample, infectious pathogens are assumed to be present as well and the water is considered unsafe for drinking 4. Dissolved Oxygen (DO) 1. amount og oxygen dissolved in given volume of water at given temp. and atmospheric pressure 2. usually expressed in parts/million (ppm) 3. good indicator o water quality and kinds of life it will support 4. Biochemical Oxygen Demand (BOD) 1. standard test for measuring amount of dissolved oxygen utilized by aquatic microorganisms

2. Chemical Oxygen Demand (COD) 1. measure of all organic matter in water 5. Oxygen Sag 1. oxygen decline downstream from pollution source that introduces material w/ high biological oxygen demands 4. Nutrient-Eutrophication 1. Water Clarity (transparency) 1. affected by sediments, chems. and abundance of plankton organisms 2. useful measure of water quality/pollution 3. Oligotrophic 1. condition of rivers/lakes w/ clear water and low biological productivity 2. usually clear, cold, infertile headwater lakes/streams 4. Eutrophic 1. rivers/lakes rich in organic material 2. Cultural Eutrophication 1. increase in biological productivity/ ecosystem succession caused by human activities 2. caused mainly by increased nutrient input into a water body 5. Inorganic Pollutants 1. some toxic inorganic chems. naturally released into water from rocks by weathering processes 1. mining, processing, using and discarding minerals are humans way of accelerating transfer rates in these cycles 2. Chems. of greatest concern: 1. heavy metals-mercury, lead, tin and cadmium 2. Supertoxic Elements- selenium and arsenic 3. Other- acids, salts, nitrates and chlorine 6. Organic Chems. 1. 2 principal sources of toxic organic chems. in water are: 1. improper disposal of industrial/household wastes 2. pesticide runoff from farm fields, forests, roadsides, golf courses and private lawns 7. Sediment one of the most abundants pollutants 1. fills lakes/reservoirs, obstructs shipping channels, clogs hydroelectric turbines and makes water purification more costly 2. smother gravel beds 3. blocks sunlight 4. Thermal pollution 1. artificially raising/lowering of temp. of a water body in a way that adversely affects biota or water quality 6. Persistent Challenges 1. sediment, nutrients, and pathogens= greatest impediments to improving water quality 1. esp. from nonpoint discharges of pollutants 2. ~ ¾ water pollution in U.S from soil erosion, fallout of air pollutants and surface runoff from urban areas, farm fields and feedlots 1. as much as 25% of fertilizer spread on farmland carried away by runoff 3. Groundwater Hard to Clean 1. ~ 4.5 trillion liters contaminated water seeps into ground in U.S from septic tanks, leaking underground storage tanks at gas stations, municipal/industrial landfills/waste disposal sites, surface impoundments, agricultural fields, forests and abandoned wells

1. waste disposal sites most toxic 2. Agricultural chems./wastes responsible for largest total volume of pollutants/area affected 4. Ocean Pollution has Few Controls 1. Toxic Chems, heavy metals, oil, sediment and plastic refuse affect most attractive/productive ocean regions 7. Water Treatment/Remediation 1. Cheapest/Most effective way to reduce pollution=avoid producing/releasing it in the first place 2. Non Point Sources require Prevention 1. Soil Conservation practices on farmlands aim to keep soil/contaminants on fields 1. precise application of fertilizer, irrigation water and pesticides saves money/reduces water contamination 2. preserving wetlands also protects surface/ground waters 2. Urban Areas 1. reducing waste that enters storm sewers essential 3. Municipal Treatment- 3 levels of Quality 1. Primary Treatment 1. process that removes solids from sewage before it is discharged/treated further 2. Secondary Treatment 1. bacterial decomposition of suspended particulates and dissolved organic compounds that remain after primary sewage treatment 3. Tertiary Treatment 1. removal of inorganic minerals and plant nutrients after primary/secondary treatment of sewage 8. Legal Protections for Water 1. Clean Water Act 1. goal to return all U.S surface waters to fishable and swimmable conditions 2. requires discharge permits and use of best practicable control tech. (BPT) 3. sets national goals of best available, economically achieveable tech. (BAT) 1. zero discharge goals for 126 priority toxic pollutants 2. CWA Permitting Systems 1. Total Max. Daily Load (TMDL) standards 1. for water bodies not meeting water quality goals 2. amount of a particular pollutant water body can receive from nonpoint/point sources...