NATURALLY OCCURRING ARSENIC LEVELS: A METHOD COMPARISON

Occurring naturally in soil, water, air, and food, arsenic is a tasteless, odorless semi-metal that can be further introduced into the environment via anthropogenic pathways. Awareness of arsenic and the potential dangers of contamination have been steadily growing, and in January of 2006 the EPA passed legislature requiring public water systems to meet a maximum contaminate level of 10 ppb for drinking water. At this time the EPA is not in a position to monitor private drinking sources, such as wells, which supplies drinking water to 22% of Georgia residents. In 2009, fourteen well water samples were collected in the Carroll County area and tested for arsenic at the University of West Georgia using the non-EPA approved Hach powder testing kit. Two samples were found to have arsenic levels between 10 and 30 ppb, three samples had undetectable levels, with the majority detecting approximately 10 ppb. Twenty-three additional samples were collected from the Carroll County region within the last three years, however, analysis was conducted at the University of Georgia’s Laboratory of Environmental Analysis using EPA approved ICP-MS. Arsenic levels from the samples tested using ICP-MS ranged from 0.002 ppb to 1.497 ppb. A noticeable trend of higher arsenic levels detected using the Hach method was apparent; eight additional samples were collected from Carroll County, with two samples taken from each site, to compare the Hach and ICP-MS testing methods. A large discrepancy was found between the results of the two methods. Furthermore, results using the Hach method could not be replicated. Ions and elements that are known by the Hach company to interfere with results such as sulfide, selenium, antimony, tellurium, calcium carbonate, and iron were taken into consideration, however iron was the only element tested for and the concentration of the metal in the samples was not significant enough to obstruct results. Further research is required to determine the concentrations of all substances known to interfere with the Hach testing kit.