SULFATE CONCENTRATION OF SURFACE AND GROUNDWATER OF THE PIEDMONT OF WEST GEORGIA: VARIATIONS WITH ROCK TYPE, LAND USAGE, FLOW CHARACTERISTICS, AND HUMAN ACTIVITIES

The aqueous concentration of sulfate in surface and groundwater is mostly controlled by dissolution and deposition of mineral and amorphous solid phases, dissolved oxygen, atmospheric deposition, biological interactions, point and nonpoint sources from human activities. In the Piedmont of west Georgia naturally high sulfate concentrations are associated with pyrite-rich rocks. For example, fresh deep road cuts in graphite-pyrite-muscovite-quartz schist have resulted in continuous flow of water in a drainage ditch with a pH of 3.7, 113 - 191 mg/L sulfate, and 5-26 mg/L iron (Bergstrom and Hollabaugh, 1999). One deep flowing artesian well in Carroll County averages 9 mg/L sulfate. Our research concentrates on surface waters. The study initially analyzed sulfate at 70 sample stations on 38 streams in two counties in west Georgia. Many streams in the study have sulfate levels below our detection level of 1 mg/L. From the 70 sample stations the 24 with detectable sulfate concentrations were monitored 12 or 52 times during 2001. Range of all samples from all 24 sample stations vary from below detection level to over 80 mg/L sulfate. The highest average is 17.5 mg/L sulfate in a small stream that has treated sewage discharged into it. Other streams with high sulfate include one draining a swamp and a stream that heads in an urban area outside the study area. The highest measured sulfate of 86 mg/L occurs in the New River in Heard County (it ranges from 1 to 86 mg/L sulfate). The New River receives treated sewage and heads in an urban area of a county east of the study area. Mud Creek, a tributary of the Little Tallapoosa River in Carroll County, has sulfate levels ranging from below 1 mg/L to 65 mg/L. This creek heads in a cattle pasture and receives treated sewage.