1. The Effect of Chromium on Algal Populations Peter Chekan Central Catholic High School Pittsburgh

2. Surface Runoff Flow of water from rain or snow melting Soil's saturation level is filled to capacity Water goes into rivers and lakes Water picks up dangerous chemicals Pesticide, insecticides, and chromium

3. Chromium Runoff Because of its solubility, it poses a threat to aquatic life. It is often used in paints, dyes, and chrome plating.

4. Chromium 24 th element in the periodic table. Heavy metal Soluble in water Breaks up into ions Hexaaquachromium or [Cr(H2O)6]3+. Potassium Chromate

5. K 2 CrO 4 Yellow Powder form Soluble in water Used as a solution in experiment

6. Euglena Protist Single celled algae Lives in fresh water Oval shaped Between 20-300μm long Bottom of the food chain Used as an experimental algal model

7. Materials Spectrophotometer Test Tubes Test Tube Rack Potassium Chromate Euglena sp. Macro Pipettes Micro Pipettes Pipette tips Spring Water

8. Purpose Determine if chromium inhibits the growth of aquatic life To estimate the minimum concentration of potassium chromate detrimental to euglena

9. Hypothesis The potassium chromate concentrations will not significantly affect euglena population growth

10. Procedure The following experimental tubes were created

11. Procedure Continued The test tubes were placed in a dark room with a controlled source of light for 12 hours All tubes were mixed by inversion prior to spectrophotometry The absorbance of algae was measured everyday by a spectrophotometer using a wavelength of 430nm Absorbance was recorded everyday for 20 days

13. P=0.02227 P=.0067 P=.00676 P=.0041 P=.0068 P=.0052

15. Conclusion The Statistical analyses allow a rejection of the null hypothesis, indicating that potassium chromate can significantly effect euglenas population growth All tested potassium chromate concentrations resulted in significant changes in the euglena populations

16. Limitations/Extensions Use lower concentrations of chromium Use larger sample sizes Test different types of algae Test natural aquatic systems

17. References http://en.wikipedia.org/wiki/Euglena http://en.wikipedia.org/wiki/Chromium http://topsoil.nserl.purdue.edu/nserlweb/weppmain/ overview/runoff.html http://topsoil.nserl.purdue.edu/nserlweb/weppmain/ overview/runoff.html http://en.wikipedia.org/wiki/Surface_runoff http://www.chemguide.co.uk/inorganic/transition/chr omium.html http://en.wikipedia.org/wiki/Potassium_chromate http://www.jtbaker.com/msds/englishhtml/p5642.ht m