Review Water Pollution

Major Water Pollutants Human wastewater: sewage & gray water Decomposition of organic waste → Huge O2 demand Excess nutrients (N & P)  eutrophication Disease-causing organisms (esp. E. Coli & Cholera) Metals (Pb, Hg, As, Cd) Acid – rain, deposition, runoff Synthetic Organics (pharma; pesticides; Military & Industrial compounds) Oil Solid Waste (especially plastic!) Sediment - erosion - turbidity Thermal & Noise pollution

Water Pollution: Point Sources - Discharge pollution from specific locations (single point). EASY TO MONITOR/REGULATE Effluent Factories, power plants, oil wells Non-Point Sources - Scattered or diffuse, having no specific location of discharge. HARDER TO CONTROL!! Agricultural fields, feedlots, golf courses

Disinfect: Chlorine Ozone U.V. light Primary sewage treatment: a physical process that uses screens and a grit tank to remove large floating objects and allows settling. Secondary sewage treatment: a biological process in which aerobic bacteria remove as much as 90% of dissolved and biodegradable, oxygen demanding organic wastes. . Tertiary Step Usually not present Expensive Added to remove specific pollutant usually N & P

Water Quality Indicators Know your list – be able to give examples / sources / causes / effects N & P Biodiversity: macroinvertebrates, fish, plants, amphibians, algae, bacteria DO / BOD / CO2 Fecal coliform – indicator Temp Turbidity Heavy metal / pH – how linked? Color / odor Synthetic Organic Compounds – Pesticides Gender benders Pharmaceuticals – antibiotics, hormones Ammonia Chlorine Hardness

Eutrophication Natural vs. Cultural Oligotrophic: nutrient-poor water Eutrophic: nutrient-rich water Sources - agricultural runoff (fertilizer, feedlots), detergents (P only), disturbed soil, products of decomposition (so any organic matter) Indicators - Elevated N and P levels Decreased DO levels, increased BOD levels Cloudy water: from algae and cyanobacteria Effects – Eutrophication  nutrients ↑, algae grows, blocks sunlight, dies and decomposes, O2 ↓ Dead zones

Gulf of Mexico Dead Zone Worst in summer Affects fish & shrimp harvests

Milk Lab Be able to describe in detail what happened & why Farm or animal feedlot Be able to describe impact of runoff

Oxygen Sag Curve Clean Zone DO high BOD low Pollution enters stream Decomposition Zone DECOMPOSITION increases to break down pollution OXYGEN decreases as it is used up by decomposers Septic zone – DEAD ZONE - Hypoxic dissolved oxygen levels are very low and very few species can survive Recovery Zone Waste concentrations decrease DO , BOD  DO is high, BOD is low and normal biodiversity levels are present. demand

Clean Water Act - 1977 EPA to set water quality standards for industry and for all contaminants in surface waters regulates discharges of pollutants in the US - point sources Requires a permit to discharge any pollutant into a navigable waterway. Goal: Make lakes & streams fishable & swimmable sets daily limits for total pollutant discharges Total Maximum Daily Load (TMDL)

Safe Drinking Water Act - 1974 established to protect the quality of drinking water in the U.S All waters designed for drinking use - above ground or underground sources EPA sets Maximum Contaminant Levels (MCLs) for drinking water Standards for dozens of contaminants