NUTRIENT LEVELS AND VARIATION OF STREAMS IN THE LITTLE TALLAPOOSA WATERSHED CARROLL COUNTY, GEORGIA

The West Georgia Watershed Long Term Monitoring project is a follow up to an intense watershed assessment performed on the lakes, streams, and tributaries of the west Georgia region in 2001. Since that time and on-going, the Center for Water Resources has maintained a long term monitoring program on fifty sample stations, with monthly sampling of 20 water quality parameters. Students are employed in all aspects of the project, from field and laboratory duties to database management. Nutrients play a critical role in a watershed and are necessary for life, but there can be too much of a good thing. Phosphorus can limit plant productivity and can lead to eutrophication, while excess amounts of nitrogen can result in groundwater contamination and secondarily lead to eutrophication.

Nutrient parameters examined during the monitoring project were total phosphorus and nitrogen as nitrite-nitrate-N, ammonia-N, and TKN (Total Kjeldahl Nitrogen – the sum of ammonia nitrogen and organic nitrogen). Both ammonia and phosphorus samples were analyzed within 24 hours and TKN & NNN samples were acidified for preservation. All nutrients were analyzed using a Hach DR/2010 spectrophotometer. Total phosphorus was measured by acid persulfate digestion, using the Hach PhosVer3 Test ‘N' Tube procedure. Ammonia was determined using the Hach Nessler method. Nitrite-nitrate-N was determined by a cadmium reduction tube. Nitrate is reduced to nitrite while in contact with cadmium in a reduction tube and the nitrite is measured calorimetrically. TKN samples are first digested at 380oC to convert the organic amino nitrogen and free ammonia to ammonium, and then the ammonia is distilled and measured using the Nessler method. Results show that nutrient levels are generally low except where streams are affected by sewage discharge and runoff from farmland. For example, a site that is affected by sewage discharge, runoff from a cattle pasture, and an industrial site can reach nitrite-nitrate-N of 1-4 mg/L and total phosphorus of 1.3 mg/L. High ammonia-N levels of 1-1.5 mg/L are produced at the bottom of Sharpes Creek Reservoir during summer stratification.