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UTSCEESA11H3MIDTERM EXAMSTUDY GUIDE
Lecture 7: Water Pollution Part 1The water cycle Sources and pathways of water pollution oAgriculture growing corpsoAgriculture animal operations oTimber-cutting operations oConstruction cities oCities/suburbs (paved surfaces) oIndustrial outfalls oMining operations Two major types of water pollution oPoint source specific spot (pipe, ditch, ship or smokestack)oNonpoint sources runoff across large areas, urban areas (streets, parking lots, roofs), rural (agriculture, logging, mining sites)Watershed oA watershed includes all the land that drains to a common body of water. oUsing a watershed-based approach to wetland protection ensures that the whole ecosystem is protected. oPolluted runoff can influence waters distant from its origin oWetlands oAquifers (groundwater)Sewage Pollution oSanitary sewer wastewater from homes/commercial places to a treatment plant oStorm sewer carries street runoffoCombined sewer carries both sanitary wastewater and storm runoffheavy storms (discharges into the water bodies)Atmospheric deposition upon land and water oNon-point source pollution PCBs (polychlorinated biphenyls) Metals (lead and mercury)Nitrogen oxides (NO3- Nitrate input)Conventional pollutions find more resources at oneclass.comfind more resources at oneclass.com
oBiochemical oxygen demand (BOD)Dissolved oxygen (DO) needed for microorganisms to decompose waste 14mg/L for low temperature and salinity 6mg/l of DO for high temperature and salinity Lots of sewage = high BOD= less oxygen available Hypoxic (low oxygen) conditions fish moves away but crabs and snails may die Total biochemical oxygen demand CBOD carbonaceous biochemical oxygen demand NBOD Nitrogenous biochemical oxygen demand Total BOD=CBOD+NBODBacteria are capable of oxidizing ammonia to nitrite and subsequently to nitrate (starts 6-7 days after CBOD)Lo= the amount of oxygen used to completely decompose or stabilize all the biodegradable organics in a given volume of water is called the ultimate BOD or BODLoNutrientsManufactured fertilizesContain concentrated reactive nitrogen and phosphorus (extra portion runs off into water bodies)Cascade effects stimulate plant growth in water bodies (algae), as the vegetation die it becomes BOD, bacteria also digest the fecal pellets of zooplankton Reactive nitrogen = bioavailable nitrogen (ammonia and nitrate) Oxygen sag downstream of an organic source (U.S.EPA)Clean zone Decomposition zone Septic zone Recovery zone Eutrophication Enrichment of body water Eutrophic lake oLots of nutrients oPoor light penetration oLow dissolved watersoShallow watersoHigh algal growth oSilt, sand, or clay bottonoCloudy water Oligotrophic lake oFewer nutrientsoGood light penetration oHigh dissolved oxygen oDeep waters oLow algal growth o