Department of Civil & Environmental Department of Civil & Environmental EngineeringEngineering

University of UtahUniversity of Utah

Sediment Oxygen Demand & Nutrient Flux Studies in Jordan

River

Dr. Ramesh GoelDr. Ramesh GoelAssistant ProfessorAssistant Professor

Civil & Environmental EngineeringCivil & Environmental EngineeringUniversity of UtahUniversity of Utah

CONCEPT ON SEDIMENT OXYGEN DEMAND (SOD)

Sediments

WaterO2Nutrients

Organics etc

SEDIMENT OXYGEN DEMAND

SOD is a combination of all of the oxygen-consuming processes that occur at or just below the

sediment-water interface.

Most of the SOD at the surface of the sediment is due to the biological decomposition of organic

material and the microbially facilitated nitrification of ammonia

SOD several centimeters into the sediment is often dominated by the chemical oxidation

HowHow to Measure SOD?to Measure SOD?

PumpPump

DOT = Sediments + Water column DOW = Water column only

SOD = DOT – DOW

Methodology

Schematic of SOD Chamber

CONTROL

ANALYSIS

Equation used for the SOD rate:

SOD t = sediment oxygen demand rate (g/m2d)b = slope of the oxygen-depletion curve (mg/L-min)V = the volume of the chamber (L)A = the area of bottom sediment covered by the chamber (m2)1.44 = units-conversion constants

SOD20 = the rate at 20°C t = in °C

Source: Parkhill and Gulliver, 1997

SOD Rate Estimation

SOD- 2300S site

Slope of SOD 1 = 0.0065 mg/L-min

Slope of Control =0.0005 mg/L-min

Net SOD = 0.0065-0.0005 =0.0060= 0.006 * 1.44 * 240 =2.073 g/m2-day

Initial linear data is used

SOD RatesLocation

CoordinatesTemperatu

re(0 C)

SOD rate

(g/m2-day)

SOD20oC(g/m2-day)

980 S, 900 W (Peace Gardens)

19.78 7.56 7.66

280 N, 1460 W 22.27 1.93 1.67

4800 S, 580 W 19.83 2.18 3.77

Legacy Nature Preserve

22.13 3.9 2.89

9000 S ,900 W 16.02 1.54 1.20

Difficulties

Bed-sediment heterogeneities Measurement errors

Possible disturbances during chamber placements

Sampling errorsControl chamber data

fluctuations

Acknowledgements Mr. James Harris, Utah Department

of Water Quality Mr. Carl Adam- Utah DWQ Leland Myers- Great inspiration The whole water quality personnel

Questions???

Thank You!!!