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Lecture 4

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BIOL 354
Bruce Greenberg

Lecture 4: Inorganic Pollutants Inorganic pollutants are one of the major classes of environmental pollutants Incude: -Metals: ie. Copper (Cu) -Metalloids: ie. Arsenic (As) -Non-metallic inorganics: ie. Ammonia -Inorganic gases: ie. CO2 Metals: Background -metals are elements: cannot be created/destroyed -lustrous appearance, malleable, good electrical conducters -metal bioavailability and toxicity affected by chemical speciation -metals can be required, toxic, or both: depends on metal and concentration Metals with greater density of iron Heavy metals -term still sometimes used -ie. Hg, Pb, Cd Metalloids are non-metallic elements -less lustrous, semi-conductors -ie. Se, As Metals/Metalloids of Concern -Aluminum, Arsenic, Antimony -Barium, Beryllium, Boron -Copper, Cadmium, Chromium, Cobalt -Iron, Lead, manganese, molybdenum -mercury, nickel, strontium -Selenium, Silver, Tin, Thallium, Vanadium, Zinc Normal Metal Functions in Biota -many metals are required by organisms (ie. Iron, Copper, Zinc//’D’.) -essential metals can be incorporated into macromolecules or .may act as enzyme cofactor Ie. Haemoglobin (Fe3+) or chlorophyll (Mg2+), mitochondria (Cu2+) Important metal ions include: -Na+ osmoregulation -K+ Membrane potential -Ca2+ Various functions, (ie. Muscle contraction) Classes of Metals -can classify metals other than on density -2 classes: A and B -classifications based on binding of metal to ligands Class A Metals -O>N>S -oxygen seeking (Ca2+, Na+, Mg2+, Pb) -associate with: Carboxyls, carbonyls, alcohols, phosphates Molecules they target Include: Phospholipids: Cell membrane Nucleic Acids: DNA, RNA ATP, ADP Class B Metals -S>N>>O -sulfur/nitrogen seeking (Cu2+, Cd2+, Hg2+) -associate with: Sulphydryls (-SH), disulphites (-S-S), thioethers (-S-R), and amines (-NH2) Molecules they target include: -amino acids -proteins -free nucleotides Metal Occurrence -naturally occurring -human activity greatly contributed to increase in metal levels in environment  metal more bioavailable (alters distribution and availability) anthropogenic activity ie. Metal mines, smelting Sources of Metal Pollution -because metals are not biodegradable they persist in the environment -ubiquitous in the environment in soil, sediment, surface water -low concentrations -weathering of metal-bearing rock and soil plays role in distribution -Anthropogenic sources of metal pollution: Industry: Metal mining, metal refining Yellowknofe’s Giant Mine clean up costs to double -giant mine operated as gold mine from 1940s to 2004 -to release gold, ore roasted at extremely high temperatures. This process released arsenic rich gas highly toxic by-product Arsenic Contamination -result of how gold was mined at the site during gold roasting process -evidence of substantial seepage from Giant Mine ponds into nearby environment -Arsenic trioxide (water soluble dust) considered carcinogenic, can cause kidney and liver failure and pulmonary edema. (lethal dose: 120mg) -cleanup plan is to freeze dust in place Sources of Metal Pollution Anthropogenic sources Urban waste: -disposal and leaching of metals from garbage, solid waste, human and animal waste with metals (processed sewage (sludge) can contain high Cd levels restrict use for agricultural land fertilizer) Agriculture metal based pesticides may contain mercury or arsenic Other Sources: -Ash, cinders: plants/animals take up metals  once burned metals remain in concentrated levels -Paints: lead and tin based paints used in the 60’s and 70’s (even today) – on toys, boats, etc. Natural Leach
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