The test temperature should be recorded and factored for temperature correction at a specific temperature.SOD curves can be plotted showing the accumulated DO used (y-axis) versus elapsed time (x-axis). SOD curves resemble first-order carbonaceous BOD curves to a great extent; however, first order
kinetics are not applicable to the Upper Illinois Waterway’s data. For the most part, SOD is caused by bacteria reaching an “unlimited” food supply.
Consequently, the oxidation rates are linear in nature. The SOD rates, as taken from SOD curves, are in linear units of milligrams per liter per minute (mg/(L . min)) and can be converted into grams per square meter per day (g/(m2 . d)) for practical application. A bottle sampler SOD rate can be formulated as:
where SOD = sediment oxygen demand, g/(m2 . d)
S = slope of stabilized portion of the curve, mg/(L . min)
V = volume of sampler, L
A = bottom area of sampler, m2