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ENVE 3503 Environmental Engineering. Units of Concentration (the lingua franca of the field). Dr. Martin T. Auer MTU Department of Civil & Environmental Engineering. Why concentration?. driving force for - mass transport chemical reactions biotic effects nutrients toxicity.
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ENVE 3503 Environmental Engineering Units of Concentration (the lingua franca of the field) Dr. Martin T. Auer MTU Department of Civil & Environmental Engineering
Why concentration? • driving force for - • mass transport • chemical reactions • biotic effects • nutrients • toxicity
Onondaga Lake Syracuse, New York Mass concentration units: mass per mass.
Onondaga Lake, Syracuse, New York Bioaccumulation: Mass in Fish vs. Mass in Water
Mass concentration units: mole per volume. Molarity (M, moles per liter) is often used to report concentrations in water. The advantage here is that the units are consistent with the stoichiometry of the reaction. A mole is one gram molecular weight of a substance. A gram molecular weight is the mass of a substance, in grams, that is numerically equal to its molecular weight. Thus one mole of carbon, C, weighs 12g, one mole of oxygen, O2, weighs 32 grams and 1 mole of CO2 weighs 44g. A 1 molar solution of CO2 would contain 44g per liter. In environmental applications, we more typically encounter millimoles (mM) and micromoles (µM), i.e. based on mg/L and µg/L, respectively.
Other types of units: concentration as a common constituent.
Organic Matter. … what’s in here?
Carbohydrates (sugar and the polymers starch and cellulose) Proteins (polymers of amino acids) Fats (formed from glycerol and fatty acids) Organic Matter. Fats (
Organic Matter. Photosynthesis Respiration also …mineralization oxidation stabilization
Representation by Effect - Organic Matter. Respiration When organic matter is used as a substrate for respiration, … when it is oxidized … when it is mineralized … when it is stabilized it exerts a “biochemical oxygen demand” or BOD.
BOD - Representation by Effect. … impacts on lakes and rivers?