Water Pollution:

Bacterial

Chemical

Industrial, municipal,

Organics, Pesticides

Inorganics, Heavy metals

Salts

Radionuclides

Sediments

Taste, color, odor

Organically bound metals and metalloids

Complexed or Chelated:

Organometallics

Metal bound to alkyl groups

eg: Tributyltin chloride

Metal Carbonyls

Nickel carbonyl

Metals bound to unsaturated organics such as ethylene or benzene

Inorganic Species

Cyanide

Ammonia

Hydrogen Sulfide

Nitrite ion

Sulfite ion

Carbon, Hydrogen, Oxygen all present in abundance--from air and water.

Potassium, Phosphorous, Nitrogen ---major nutrients usually furnished as fertilizers in agriculture

Other major nutrients, Mg, Ca, S present usually on minerals, soils

Eutrophication

Acidity, Alkalinity and Salinity

Pollutant acids

Mine drainage (Sulfides and bacteria ® sulfuric acid)

Alkalinity and high pH (often natural-- alkali flats of West)

Oxygen, Oxidizing agents, and Reducing agents

BOD and TOC-- What is measured and what’s the difference between these??

Sewage treatment: Oxygen demanding substances removed in primary and secondary treatments.

Salts, refractory organics, heavy metals not well removed.

Soaps, detergents, builders

Soaps--biodegradable, easily precipitated out by Ca ⁺², Mg⁺², (advantage in cleanup of waste, disadvantage in laundry!)

Alkyl sulfate

Alkyl benzene sulfonate (ABS)

Builders

polyphosphates

ion exchangers

sodium carbonate

sodium silicates

amide foam stabilizer, soil suspending agent carboxymethyl cellulose,

softeners, optical brighteners, fragrance, dye

Biorefractory Organics

Industrial synthetic organic chemicals

• Aromatics, including:
  benzene, alkylated and halogenated benzenes
  biphenyls
• Halogenated 1 and 2 carbon hydrocarbons
• Many others

How to remove?

• Carbon Adsorption
• Air stripping
• Ozonation
• Solvent extraction

Not all these methods are practical!

Pesticides

Insecticides

Molluscicides

Nematicides

Rodenticides

Herbicides, defoliants, and plant growth regulators

Fungicides

Bactericides

Slimicides

Algicides

365,000,000 kg pesticides used in agriculture in US each year

900,000,000 kg insecticides used in US for non agricultural purposes

Natural Insectides

Nicotine, Rotenone, Pyrethrins

Advantage: Being natural they are easily biodegraded

DDT and the Organichlorinated Insecticides

DDT

Chlordane, Aldrin, Dieldrin, Heptachlor, Lindane

Organophosphate Insecticides

Parathion, Malathion

Parathion more toxic, malathion can be deactivated by mammalian enzymes, which insects do not ahve

Generally quite biodegradable

Carbamates

Derivitives of Carbamic acid--Acetylcholinesterase inhibiters

Herbicides

Bipyridilium -- Diquat, Paraquat

Nitrogen heterocycle Herbicides

Chlorophenoxy Herbicides

Substituted Amides

Nitroanalines

Arsenic trioxide!

Important By-products of Pesticide Manufacture

Hexachlorobenzene (raw material for some processes)

Polychlorinated dibenzo dioxins

Not a serious water pollutant--low solubility

The Seveso Accident

Times Beach, MO

Polychlorinated Biphenyls

Very stable sediment pollutant in waterways, bioaccumulates in food chain,

Possible biodegradation--but very slow--Anerobic bacteria remove Cl from highly chlorinated forms, then aerobic bacteria degrade the 1 and 2 Cl forms.

Radionuclides

Emit ionizing radiation:

a Particle: 2 protons, 2 neutrons (Helium nucleus) Charge = +2, Mass = 4 AMU

Ionizes ~ 1/2 of the atoms it encounters. Path length is ~ 0.05 mm in water. Not a problem from outside body, can cause damage if ingested or inhaled

b particle: an energetic electron, b ^- (or positron, b ⁺), Mass is very small, and ionizes only 1/1200 atoms encountered. Path length is longer, ~ 3 cm in water.

g ray: Not a particle. Very energetic, probability of hitting another atom is lower, but when it does, it transfers much energy, and secondary ionizations are likely. Wide range of energies and penetration depths.

Current human exposure in US:

Natural radiation ~80%

Radon, cosmic rays, rocks and soil, ingested natural isotopes

Artificial ~20%

Medical, occupational, nuclear power emissions, weapons tests

Kinetics of Radioactive decay

Persistence vs. Intensity. Measured by

decay law:

or by activity

or by half life:

Units: Curie = 3.7 x 10¹⁰ disintegrations / sec

• What is the half life of an isotope which shows an activity of 87699 counts/min and 42231 exactly 2 hours later?

• A herbicide is put into a pond which is roughly circular and is 100 meters across. The pond is approximately 5 meters deep on average. If the herbicide will kill the weeds at a level of 30 ug/l, how much is required?