Major Determinants of Water Quality and the Impact or Availability of Water Pollutants Organisms Solubility Oxygen pH Nutrients (N, P) Metals (Hg, Pb, As) Organic Chemicals (PCBs, Dioxins)
Nutrients: Nitrogen and Phosphorus Both are limiting to primary productivity Excess amounts can severely alter ecosystems Sources: fertilizers, manures, wastewater discharge Availability in the environment is controlled by Oxygen pH Organisms
Nitrogen Dominant Forms: NH4+ and NO3- Forms are controlled by organisms NH4+ is converted to NO3- by aerobic bacteria NO3- is much more mobile in the environment than NH4+ Forms are controlled by Organisms Oxygen pH
Surface Water and Nitrates the highest density of point sources in the entire St. Johns River. Within this area, the river receives about 30 percent of its total amount of nitrate and ammonia nitrogen and 33 percent of its phosphate Large, prolonged high tides can cause water to reverse its flow in the river as far upstream as Lake George. This delays the dispersal of pollutants. The roughly 30,000 acres of row crop agriculture in this area of the river basin supplies 40 percent of the spring season inorganic nutrients that enter the river between Palatka and Green Cove Springs. Algae typically peak in this area. Wastewater Treatment Agriculture Slow Flow of contaminants As the lower St. Johns River widens downstream of Palatka, the speed of water flow decreases, making the river lake-like and making conditions favorable contaminant accumulation. St. Johns
Lower Suwannee River Watershed • residential and commercial septic systems in rural areas • about 300 row crop and vegetable farms • 44 dairieswith more than 25,000 animals • 150 poultryoperations with more than 38 million birds Nitrates NO3 Drinking water standard: 10 ppm
Phosphorus Availability and pH Low pH High pH Aluminum and Iron phosphates Calcium Phosphates Insoluble solids There is a limited ability of soils to immobilize phosphorus If the capacity is exceeded, phosphorus becomes mobile Mobile phosphorus can contaminate surface and groundwater
Phosphorus loading to S. Florida Ecosystem Dairy/Beef Inputs North and South of Okeechobee Agriculture (EAA) Kissimmee Basin
Everglades Agricultural Area Organic soils possessing high natural fertility Historically flooded
Water restricts the movement of oxygen The diffusion of oxygen through water is about 1000 times slower than diffusion through air Flooded Marsh Under flooded conditions, oxygen levels tend to be low Anaerobic heterotrophs: live in low-oxygen environments
Aquatic Plants and Algae Die Heterotrophic microorganisms decompose tissues Aerobic heterotrophic organisms use oxygen Oxygen becomes depleted in water; it cannot diffuse fast enough to support aerobic heterotrophs Anaerobic heterotrophs become dominant
Anaerobic respiration is less efficient and produces less energy. e- C6H12O6 + 6O2 → 6CO2 + 6H2O 2880 kJ C6H12O6 + 3NO3- + 3H2O = 6HCO3- + 3NH4+ 1796 kJ C6H12O6 + 3SO42-+ 3H+ = 6HCO3- + 3HS- 453 kJ Therefore, anaerobic decomposition is much slower than aerobic decomposition.
Buildup of Organic soils Organic matter decomposes slowly when submerged in water. (anaerobic decomposition) Soils throughout the glades historically have been submerged. (anaerobic conditions) Led to vast amounts of organic matter accumulation, sometimes >20 ft. thick. Organic matter continues to accumulate as long as flooded conditions persist.
Drainage EAA Drainage exposes soils to oxygen and decomposition by aerobic heterotrophic organisms which can more efficiently decompose organic matter
Subsidence of Organic soils Greater than 10 feet
Heavy Metals and Metalloids Arsenic Erosion of natural deposits; pesticide waste, runoff from glass & electronics production wastes, treated lumber, groundwater Mercury Erosion of natural deposits; discharge from refineries and factories; runoff from landfills, coal burning Lead Corrosion of household plumbing systems; natural deposits, paint, fuels, electronics
Mercury, Arsenic, and Lead Lead found in blood sample from 1 of 10 Washingtonians Arsenic found in urine samples from 4 of 10 Washingtonians Mercury found in hair samples from 10 of 10 Washingtonians
Wonderland Mercury Nitrate Symptoms included tremors, emotional instability, insomnia, dementia and hallucinations
Lead (Plumbum) Father of all metals Possible cause of the dementia which affected Roman Emperors and Citizens. -lead pipes -lead acetate sugar of lead sweetener for wine Contemporary Sources: Paint, ceramics, glass, soils, pipes, Solder, brass faucets, gasoline
India 21 million backyard tube wells Failure of 246 surface irrigation projects $600 electric pumps (1% of GDP) 95 % water table falling by 20 feet per year What do you do when your water table falls?
Deeper Wells and Fluoride Naturally occurring element in Granite which dissolves into the groundwater Water near the surface is generally unaffected Lowering water tables = deeper wells Deep groundwater can contain high fluoride levels Fluoride in water can be a cumulative poison
Intentional Fluoridation of Water in the U.S. Fluoridation became an official policy of the U.S. Public Health Service in 1951. By 1960 water fluoridation had become widely used in the U.S. reaching about 50 million people. By 2006, 69.2% of the U.S. population on public water systems were receiving fluoridated water.
How does it work? Tooth enamel is made of a mineral called hydroxyapatite Ca5(PO4)3OH Bacteria in the mouth create acids (H+) Hydroxyapatite is subject to dissolution by acids (H+) Fluoridation changes the chemical composition of hydroxyapatite to a crystal less subject to acid dissolution
NaF Na+ + F- Sodium fluorosilicate (Na2SiF6) Sodium fluoride (NaF) Ingestion of fluoridated water increases the F- concentration in saliva F- replaces OH in hydroxyapatite making fluoroapatite F- Ca5(PO4)3 OH Fluoroapatite is less soluble in acid than hydroxyapatite
Fluoride concentrations In U.S. tap water 0.5 – 1.1 mg/L Lower values in warm climates
Dental Fluorosis Fluoride levels > 1.5 mg/L Intake: 1.6 to 6.6 mg/day Colorado Brown Stain Permissible fluoride limit in India is 1.2 mg/L Fluoride levels between 5-25 mg/L have been found
Skeletal Fluorosis Fluoride levels > 10 mg/L Intake 9 mg/day to 12 mg/day Fluorosis has risen from 1 million to 25 million and threatens 60 million people in India.
Arsenic is Naturally Occurring occurs primarily in association with sulfur-containing minerals Natural waters, in general, contain low levels of total arsenic Mobilization of arsenic in the environment arises from anthropogenic activities related to mining and ore processing, metallurgy, agriculture, wood preservation, and industry.
Inorganic Forms of Arsenic AsO4-3 AsO3-3 Arsenite Arsenate High Oxygen Low Oxygen Arsenite is more toxic than arsenate, interfering with enzyme activities which catalyze metabolic reactions Arsenite compounds are also more mobile in the environment due to higher solubility compared to arsenate compounds Both arsenate and arsenite are chronic accumulative toxins
Bangladesh and W. India ranked among the world's 10 poorest countries
Floodplain and Delta of the Ganges and Brahmaputra Rivers. Himalayas Floodplain: area paralleling a river that is periodically inundated Ganges-Brahmaputra Delta Deltas are formed from the deposition of sediment carried by the river as the flow leaves the mouth of the river Accumulation of thick muds in the floodplains and deltas
Bangladesh Prior to 1970s One of the highest infant mortality rates in the world Principally due to waterborne disease. Ineffective water and sewage systems Periodic monsoons and floods water-borne pathogens cholera, dysentery Deaths Due to Surface water contamination: 250,000/yr
Deaths Due to Surface water contamination: 250,000/yr The Solution: Tap groundwater resources • easy • inexpensive First 1 million wells were sunk with aid from World Governments UNICEF World Bank
12 million hand-operated tube wells deliver water to over 80% of the rural village population Infant mortality and diarrheal illness reduced by 50%
Wells in Floodplain and Delta Sediments Natural erosion of arsenic to water- bearing units. Well depths between 20m and 100 m Water Bearing Muds
WHO/U.S limit: 10 ppb Bangladesh limit: 50 ppb Some wells contain 500 - 1000 ppb Majority of wells > 50 ppb arsenic
Exposure Estimates Above 10 ppb: 57 million people Above 50 ppb: 35 million people Accumulative Toxin Early Symptoms: Skin lesions and thickening Strong skin pigmentation Long-term Exposure breathing problemsdeath if exposed to high levelslung and skin cancerperipheral nervous system
83 million people Bihar: 40% wells contaminated
Red River Delta 11 million people First wells sunk 7 years ago
Mercury Got Fish?
Mercury Advisories 70% of states Where does it come from?
Enters water bodies principally from the atmosphere Mercury is naturally occurring (coal, volcanism, rock weathering) The number 1 anthropogenic source is the combustion of coal 48 tons of elemental mercury to the atmosphere each year.
Mercury The drinking water standard for Mercury is 0.002 mg/L. 1 gram annually Electrical products such as dry-cell batteries, fluorescent light bulbs, switches, and other control equipment account for 50% of mercury used.