Water Quality Presented By Group 2 River Water

Water Quality Presented By: Group 2

River Water Quality �Dissolved Oxygen (mg O 2 /L) – is required to maintain a balanced community of organisms in lakes, rivers, and the ocean. �Deoxygenation – the rate at which oxygen is consumed in oxidizing an oxygen-demanding waste. �Reaeration – the rate at which the oxygen is resupplied from the atmosphere.

Oxygen Saturation and Deficit �Saturation concentration (DOsat) – the amount of oxygen that can be dissolved in water at a given temperature. �Henry’s law constant (Kh) – (1. 36 x 10 -3 moles/L-atm at 20°C) �Partial pressure of oxygen in the temperature (PO 2 ) – 21 percent or 0. 21 atm

Formula for DOsat: DOsat = Kh x PO 2 Formula for D: D = DOsat – DOact where: D = oxygen deficit DOact = ambient DO conc. from saturation

Example 8. 2 �Determine the saturation dissolvedoxygen concentration, Dosat at 20°C. Solution: Dosat = 1. 36 x 10 -3 mole/L-atm x 0. 21 atm = 2. 85 x 10 -4 mole / L Convert to mg O 2/L: Dosat = 2. 85 x 10 -4 mole/L x 32 g O 2/mole x 103 mg O 2 mole O 2 g O 2 = 9. 1 mg O 2 /L

Example 8. 3 �Determine the dissolved-oxygen deficit, D, at 20°C for a river with an ambient dissolved-oxygen concentration of 5 mg O 2/L. Solution: D = 9. 1 – 5 = 4. 1 mg O 2/L

Wetlands �A site may be characterized as wetland if it is: (1) Is inundated and saturated with water for at least part of the year. (2) Has hydric soils (3) Supports predominantly hydrophytic plants

Wetlands �Serve several important functions: - water storage and flood mitigation - filtration of water and removal of 1 suspended solids, bacteria, nutrients and toxic substances - wildlife habitat - biogeochemical cycling of materials - removes substances that may impair