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Organic Matter in Water, Nonspecific Tests |
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Test |
Description |
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BOD |
Biochemical oxygen demand. Measures the ability of common bacteria to digest organic matter, usually in a 5-day incubation at 2O0C, by analyzing depletion of oxygen. This measures biodegradable organic matter. Expressed as O2. |
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CCE |
Carbon-chloroform extract. Organics adsorbed on an activated carbon |
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cartridge are extracted from the carbon by chloroform. The extract |
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is weighed or further analyzed. |
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CAE |
Carbon-alcohol extract. Organics adsorbed on an activated carbon |
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cartridge are extracted from the carbon by ethyl alcohol. (This is |
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performed after the chloroform extraction of the same column.) |
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COD |
Chemical oxygen demand. Measures the ability of hot chromic acid |
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solution to oxidize organic matter. This analyzes both |
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biodegradable and nonbiodegradable (refractory) organic matter. |
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Expressed as O2. |
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Color |
Color. This is a rough measure of tannin, lignin, and other humic |
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matter in surface waters and certain wastes, such as kraft pulping |
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wastes. Reported in APHA units, related to platinum standard. |
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IDOD |
Immediate dissolved oxygen demand. Measures the presence of strong reducing matter in wastes which would have an immediate |
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effect in reducing the oxygen level of receiving streams. Determined by measuring reduction in oxygen 1 5 min after dilution of sample with an O2-saturated water. Expressed as O2 |
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LOI |
Loss on ignition. In this determination, the water sample is first |
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evaporated to dryness, then weighed. The solids are then heated to |
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a dull red heat and reweighed. The difference in the two weights is |
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loss on ignition. The firing step burns off organic matter, but it also |
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affects mineral composition, as in the breakdown of carbonates to |
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oxides, so the loss is not all organic. |
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O2 consumed |
Oxygen consumed from permanganate. Measures the susceptibility of |
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organic matter in sample to oxidation by KMnO4. Not as strongly |
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oxidizing as chromic acid. Preceded the COD test and still a useful |
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control test. Reported as O2. |
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Solvent |
Extractables. Measures the organic matter directly extractable from |
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extractables |
water, usually using hexane, although CCl4 and CHCl3 are also |
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used. |
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TOC |
Total organic carbon. Measures the CO2 produced from organics when a water sample is atomized into a combustion chamber. |
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The CO2 equivalent to the alkalinity may be removed first, or this equivalent may be subtracted from the total CO2 to determine organic carbon reported as C |
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