Units of Concentration the lingua franca of the

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

Metric prefixes … 1012 106 103 100 10 -3 terragram metric ton (megagram) kilogram milligram Tg MT kg g mg 10 -6 10 -9 10 -12 10 -15 microgram nannogram picogram femtogram µg ng pg fg

And if that’s not enough … 1024 yottagram Yg 10 -24 yoctogram yg

Mass concentration units: mass per mass. Onondaga Lake Syracuse, New York

Mass concentration units: mass per mass.

Mass concentration units: mass per mass.

Mass concentration units: mass per volume.

Bioaccumulation: Mass in Fish vs. Mass in Water Onondaga Lake, Syracuse, New York

Mass concentration units: mole per volume.

Mass concentration units: mole per volume.

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 12 g, one mole of oxygen, O 2, weighs 32 grams and 1 mole of CO 2 weighs 44 g. A 1 molar solution of CO 2 would contain 44 g per liter. In environmental applications, we more typically encounter millimoles (m. M) and micromoles (µM), i. e. based on mg/L and µg/L, respectively.

Mass concentration units: mass per volume.

Mass concentration units: mole per volume.

Other types of units: concentration as a common constituent.

Other types of units: particle concentrations.

Other types of units: representation by effect.

Other types of units: representation by effect.

Other types of units: representation by effect.

Organic Matter. … what’s in here?

Organic Matter. Carbohydrates (sugar and the polymers starch and cellulose) Proteins (polymers of amino acids) Fats (formed from glycerol and fatty acids)

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?