lect 18 part 1 Flashcards
what is the outline?
chapter 7: water pollution
-the following information will be left as a reading assignment
-this information will be drawn upon in the follow-up chapter on water treatment in chapter 8 in next lecture
what is the markers and biomarkers of water pollutants?
markers of water pollution that show presence of pollution sources
-herbicides indicate agricultural runoff
-fecal coliform bacteria indicate sewage sources
-pharmaceutical metabolites in domestic wastewater
biomarkers of water pollution are organisms that indicate pollution
-may accumulate pollutants that appear in analysis
-may show effects from pollutant exposure
-fish lipid tissue accumulates persistent organic pollutants
-osprey at top of aquatic food web is a good biomarker
what are elemental pollutants?
trace elements (harmful at a few parts per million or less) (in table 7.2)
-heavy metals are among the most harmful: cadmium, mercury, lead (most are sulfur seekers)
-metalloid may be significant water pollutants: most important is arsenic but selenium and antimony can also be harmful
what is table 7.2 of trace elements in natural waters?
what are heavy metals?
cadmium
-highly toxic
-chemically very similar to zinc
-from mining and industrial wastes (especially metal plating)
lead
-widely used and distributed in the past
-plumbing (lead pipe, solder) used to be a major source
-uses (such as in gasoline) have been greatly curtailed
mercury
-highly toxic
-minimata bay incident
-mobilized by bacterial methylation- HgCH3+, Hg(CH3)2
what are important metalloids?
arsenic is the most significant
-from coal combustion
-occurs with phosphate minerals
-byproduct of copper, gold, lead refining
-natural occurrence in some groundwaters
-formerly in pesticides: Pb3(AsO4)2, Na3AsO3, Cu3(AsO3)2
-Bangladesh tube well poisonings may have affected millions
what happened in the tube wells in bangladesh?
what are organically bound metals and metalloids?
have metal (metalloid) bonded to carbon
-alkyl groups such as ethyl in Pb(C2H5)4
-pi electron donors such as ethylene, C2H4
-carbonyls with bound CO
-tetraethyllead, C2H4, in gasoline introduced large quantities of lead into the environment until it was banned
-methylation of mercury by anoxic bacteria mobilized otherwise insoluble inorganic mercury
organotin compounds were widely used as marine biocides in ship and boat paints
-tributyltin chloride commonly used industrial biocide
-endocrine disruption in shellfish and oysters
-uses now being phased out
what are some inorganic species?
-cyanide
-ammonia
-free carbon dioxide
-hydrogen sulfide
-nitrite ion
-sulfite ion
-perchlorate ion
-asbestos
what is cyanide?
HCN, CN-
-extremely toxic
-industrial uses including metal cleaning, electroplating
-produces by coke ovens
-water pollution and fish kills from mineral processing
-concern for terrorist attacks on water supplies
what is ammonia?
generally as NH4+, NH3 at high pH
-added to drinking water for residual disinfection from chlorination
what is free carbon dioxide, CO2?
-in water from decay of organic matter and geochemical sources
-makes water corrosive, harmful to aquatic life (due to pH)
what is hydrogen sulfide?
H2S
-from industrial sources, decay of organosulfur compounds, geochemical sources
-foul odor, very detrimental to water quality, very toxic
-precipitates heavy metals
what is nitrite, sulfite, perchlorate ion?
nitrite ion: NO2, intermediate in reduction of NO3-
very toxic but rare water pollutant
sulfite ion: SO32-
-added to water as O2 scavenger
perchlorate ion: ClO4-
-industrial pollutant in some cases
-recognized as pollutant fairly recently
what is asbestos?
-causes cancer when inhaled, but unknown effects in water
-asbestos-like fibers in lake superior, reserve mining
what are algal nutrients and eutrophication?
eutrophication means “well nourished”
eutrophication in excess is detrimental causing heavy growth of biomass followed by decay
-consumes O2
-fills shallow water bodies
of numerous algal nutrients (table 7.3) phosphorus is generally limiting and is controlled to control eutrophication
what s acidity, alkalinity, and salinity?
acid
-pollutant acids generally strong acids
-one of the most common is acid mine water (H2SO4)
-potential industrial sources of pollution
alkalinity
-generally due to NaHCO3
-from natural geological sources
-can be worsened by irrigation practices
salinity
-salts such as NaCl and Na2SO4
-increased in municipal water systems
-increased by irrigation
-major problem, especially in heavily irrigated areas
what is oxygen, oxidants and reductants?
dissolved oxygen, DO, is important in water
-depleted by oxidation of NH4+, Fe2+, SO32- and especially biodegradation of biomass {CH2O}
{CH2O}+O2->CO2+H2O
-biochemical oxygen demand, BOD, refers to amount of oxygen consumed in a volume of water by the biodegradable organic matter in it
-total organic carbon, TOC, is often substituted for BOD
what is the bioaccumulation of organic pollutants?
bioconcentration factor (BCF):
BCF=substance conc in organism/conc in water
bioaccumulation factor, BAF, considers a pollutant concentration in food as well as sewage
-contains many pollutant including pathogenic microorganisms, detergents, salts, solids (table 7.4)
-most significant pollutant in sewage is biodegradable organic material ({CH2O}) manifested as biochemical oxygen demand (BOD)
-main objective of wastewater treatment is elimination of BOD
what is the graph of the settling of solids from an ocean-floor sewage discharge?
what are soaps?
what does alkyl polyethoxylate surfactants act as?
what are naturally occurring chlorinated and brominated compounds?
produced mostly by marine organisms
-chemical defense agents
detected in arctic samples
-air, fish, seabird eggs, marine mammals, human milk
what are microbial toxins in water? (toxins from aquatic bacteria and protozoa)
many such as cylindrospermopsin from cyanobacteria
protozoal dinoflagellata toxins cause many maladies
-gastrointestinal, respiratory, skin disorders in humans
-mass kills of marine mammals
-sometimes fatal paralytic conditions from eating infested shellfish
red tides from explosive growth of dinoflagellates
-turn water red, yellow, olive-green
-kill marine organisms
-make sea spray very irritating to humans
what are pesticides in water?
numerous kinds of compounds added to soil and plants
-insecticides, herbicides, molluscicides, fungicides, bactericides, slimicides, avicides (birds), piscicides (fish), plant growth regulators, plant defoliants, plant desiccants
-insecticides and fungicides most important for human exposure because of application near harvest time
-herbicides most important water pollutants because of widespread application directly onto soil
what are main chemicals of concern for water pollution?
- highly biodegradation resistant compounds
- known or probable carcinogens
- substances with adverse reproductive or developmental effect
- neurotoxins including cholinesterase inhibitors
- acutely toxic substances
- known groundwater contaminants
what are the natural product of insecticides?
-nicotine from tobacco
-rotenone from some legume roots
pyrethrins
-products such as pyrethrum I from chrysanthemum varieties grown in Kenya
-used in China 2000 years ago
pyrethroids are synthetic analogs of pyrethrins
-allethrin
-fenvalerate
-cypermethrin
what is DDT and organochloride insecticides?
organochloride insecticides have been mostly phased out of use because of persistence, harm to birds
-endosulfan one of the last to be eliminated
what are organophosphate insecticides?
though biodegradable and not generally environmentally harmful, some very toxic effects (acetylcholinesterase inhibitors)
what is malation?
malathion is a commonly used organophosphate because mammals can hydrolyze it to non-toxic products
what are carbamates?
esters of carbamic acid
-biodegradable
-acetylcholinesterase inhibitors but not unduly toxic
what are fungicides?
what are herbicides?
herbicides applied to millions of acres of cropland worldwide to control weeds
herbicides commonly occur in surface water and groundwater, especially in intensely cropped areas
-especially common are atrazine simazine, and cyanazine used for weed control on corn and soybeans
-although widely used to control weeds on crops genetically engineered to resist it, glyphosate has a very strong affinity for soil and rarely gets into water
what are the two major bipyridilium herbicides?
what is common in corn-growing areas?
triazine herbicides of which atrazine is especially common in water in corn-growing areas
what is chlorophenoxy herbicides?
what are some other miscellaneous herbicides?
what are pollutants from pesticide manufacture?
what are polychlorinated biphenyls (PCBs)?
-very high chemical, thermal and biological stability
-had many uses, especially in electrical equipment
-highly persistent and found in water, sediments, bird and fish tissues
-contamination of hudson river sediments from electrical manufacture
-now banned
what are the emerging water pollutants, pharmaceuticals and household wastes?
emerging water pollutants are relatively new substance coming into use that may get into water and that may have undiscovered pollution effects
-nanomaterials composed of very small particles with many developing uses including pharmaceuticals
-siloxanes (silicones) used in cosmetic products, water-repellant windshield coatings, detergents
-disinfection byproducts (trihalomethanes)
-household wastes including surfactants, flame retardants, and plasticizers (bisphenol-A)
what are pharmaceuticals and partial degradation products?
what are bactericides in water?
used in soaps, shampoos, deodorants, lotions, other
-triclosan and its methyl derivative found in swiss waters
what are estrogenic substances in wastewater?
disrupt endocrine gland activities regulating metabolism and reproductive functions of organisms
aquatic organisms (fish, frogs, alligators) exhibit:
-reproductive dysfunction
-altered sex characteristic
-abnormal serum steroid levels
substances include
-oral contraceptives
-hormonal treatments
-cancer treatments
nonionic surfactant polyethoxylates are estrogenic substances
-much less potent than hormonal substances
-but released in enormous quantities
what are biorefractory organic pollutants?
-poorly biodegradable organics
-also called persistent organic pollutants (POPs)
-include prominently chlorinated hydrocarbons
-examples are benzene, chloroform, tetrachloroethylene
-biorefractory compounds are not well removed by biological treatment and may require physical means such as carbon adsorption
what are some radionuclides in the aquatic environment?
what are some radionuclides that may be in water?
carbon-14 from cosmic processes
radium-226 from uranium
-especially significant water pollutant in some areas
fission products important in health
-strontium-90 that substitutes for calcium in bone
-iodine-131 that affects thyroid
-cesium-137 that substitutes for sodium
radionuclides are characterized by half-lives in which had of the radioisotopes decay
radiation from radionuclides damages living organisms by breaking bonds in biological macromolecules
-bone marrow may be damaged in acute cases
-genetic effects (damage to DNA) is of particular concern
