2. Water Quality ESI

3. Stream Water Mass after collecting by filtration Evaporate water after filtering, determine mass of residue TDS by conductivity since common solids are ions soluble insoluble Cause of turbidity or cloudiness of stream water Suspended solids or sediment Total Dissolved Solids (TDS) Mostly salts - ions Particles settle out

4. Suspended Sediment Does suspended sediment vary with stream discharge? Data from http://va.water.usgs.gov/chesbay/RIMP/conc.htmlhttp://va.water.usgs.gov/chesbay/RIMP/conc.html mean Mean discharge 60,000 cfs based on 34 years of data

5. How can we control suspended sediment? Use of silt fence at construction sites Settling ponds for stormwater runoff Riparian Forest buffers along streams and rivers No till/contour plowing agriculture

6. Suspended Sediment Wades in until his feet disappear! Source: www.mdp.state.md.us/info/patux.htmwww.mdp.state.md.us/info/patux.htm Late 1980’s Late 1990’s The GOAL

7. Turbidity and Light Penetration What is the biological importance of light penetration to submerged aquatic vegetation (SAV)? As turbidity increases, light penetration decreases. SAV

8. http://www.dnr.state.md.us/bay/sav/past_present.html Recovery of bay grasses has occurred! How has the area of SAV’s in the Bay region varied?

9. The importance of bay grasses Produce O 2 by photosynthesis Disperse wave energy, decrease turbidity and erosion Absorb nutrients from the water Provide food and shelter for many organisms http://www.dnr.state.md.us/bay/sav/importance.html

10. Total Dissolved Solids (TDS) Mostly dissolved mineral salts as ions (cause of conductivity) Na + Cl - Ca ++ SO 4 -2 Organic compounds Examples: rain <10 mg/L drinking water <500 mg/L rivers 100 – 2000 mg/L seawater 35,000 mg/L

11. Water Temperature How does temperature vary over a year? 200220012000 http://www.dnr.state.md.us/bay/conditions/le11.html

12. Dissolved oxygen (DO) 012345678910 mg O 2 /L water oxichypoxic anoxic Stressful Severely stressful or lethal Healthy Required by higher organisms!

13. What is the source of dissolved oxygen in stream water? Oxygen, O 2, from air (79%N 2 /20%O 2 ) dissolves in water – added by turbulence in stream flow Produced by photosynthesis by organisms such as algae CO 2 + H 2 O  (CH 2 O) x + O 2

14. Solubility of oxygen gas (O 2 ) How does the solubility change when temperature increases? Temperature, o C Solubility, mg/L Is this your prediction?

15. Now consider both the dissolved oxygen and temperature data over an annual cycle. Mean values from http://www.dnr.state.md.us/bay/conditions/pot1830.htmlhttp://www.dnr.state.md.us/bay/conditions/pot1830.html How does the solubility change when temperature increases?

16. DO is an indirect function of temperature.

17. Dissolved Oxygen in the Chesapeake Bay Monthly for 1998 August levels for 1984 to 1998 Images from http://noaa.chesapeakebay.net/data/interp1.htmhttp://noaa.chesapeakebay.net/data/interp1.htm mg O 2 /L

18. Oxygen Demand Substances that use oxygen in reactions: organic compounds + O 2  products STELLA dissolved oxygen model Lower the dissolved oxygen of streams. Once reaction is over, DO levels can recover.

19. pH 23456789101112 neutral @ 25 o C (H + ) = (OH - ) distilled water acidic (H + ) > (OH - ) basic or alkaline (H + ) < (OH - ) natural waters pH = 6.5 - 8.5 normal rain (CO 2 ) pH = 5.3 – 5.7 acid rain (NO x, SO x ) pH of 4.2 - 4.4 in Washington DC area 0-14 scale for the chemists fish populations drop off pH < 6 and to zero pH < 5

20. Nutrients nitrate (NO 3 - ) – very soluble phosphate (PO 4 -3 ) – soluble at low levels part of TDS cause excessive biological growth, which consumes DO

21. fertilizers acid rain wastewater animal feedlots detergents phosphate rock Nutrient Sources in the Environment Banned in Bay watershed Not found in Bay watershed sources of both nutrients

22. Judging Water Quality Using Macroinvertebrate Organisms in Bottom Sediments high medium low Water quality Increasing species diversity POORFAIRGOOD Organism Tolerance to Environmental Stress Wide-range tolerance Intermediate tolerance Clean water only