Temperature

What is Temperature? Temperature is the measure of the average kinetic energy in a system. May be measured in Celsius (°C) or Fahrenheit (°F).

How is Temperature Measured? Traditional thermometers Digital Thermometers

What affects temperature? Natural factors influence temperature. -Sunlight -Flow -Depth of water - Color and Turbidity -Inflow of surface water -Inflow of groundwater

Human Factors? Human factors affect temperature. -Removal of vegetation -Soil erosion -Stormwater runoff -Changes in the stream morphology -Cooling water discharges

Why is Temperature Important? Temperature can influence: -Dissolved oxygen and other gases -Rate of photosynthesis -Metabolic rate -Sensitivity of organisms to environmental factors -Biological clocks

How does temperature affect fish? SpeciesOptimal Growth Short-term Maximum Spawning (mean) Embryo Survival(max) Bluegill32°C35 °C25 °C34 °C Carp21 °C33 °C Channel Cat32 °C35 °C27 °C29 °C Largemouth Bass 32 °C34 °C21 °C27 °C Rainbow Trout 19 °C24 °C9 °C13 °C Sockeye Salmon 18 °C22 °C10 °C13 °C State Water Resources Control Board-Citizen Monitoring

Dissolved Oxygen

What is Dissolved Oxygen? Dissolved oxygen, O 2, is a requirement biological respiration in the aquatic community. It is commonly measured in mg/L (ppm). The amount of dissolved oxygen is dependent upon a number of physical and biological factors.

What Affects Dissolved Oxygen? Physical factors –Increased water temperature decreases DO. –Turbulence increases DO. –Increases in salinity decrease DO. –Oxidizing chemicals decrease DO –Altitude decreases DO Biological factors –Increased photosynthesis increases DO. –Decomposition of organic matter increases respiration and decreases DO.

How is DO measured? Colorimetric methods –Chemet system based on the oxidation of Indigo Carmine. –Rhodazine D Titration –Winkler method An iodometric method more precise than colorimetric

How is DO measured? Digital meters use a membrane system that gives more precise values than colorimetric. Based on the rate of diffusion of O 2

What is Oxygen Saturation? Dissolved oxygen can also be expressed in % saturation. This is a measure of how much oxygen the water should be able to hold. Saturation is temperature dependent. A nomograph shows the relationship.

Using a nomograph or ppm

How Do Dissolved O 2 and Temperature relate? Values are for fresh water at sea level. Derived from: Standard Methods for the Examination of Water and Wastewater.

What is BOD? Biochemical oxygen demand is a measure of how much potential biological or chemical load is in the water that may use up oxygen over a period of time. Microbes that decompose material increase BOD and thus can decrease DO over time.

How is BOD Measured? Use one sample bottle for the water sample from which you measure initial DO (DO initial ) Use another sample bottle with no air bubbles to store in the dark for 5 days Sample this bottle for the end DO (DO 5day ) DO initial – DO 5day = BOD

Oxygen Sag Curve

Dissolved Oxygen SEE HANDOUT Using probes Using titration (Winkler) method