INVESTIGATING THE EFFECTS OF VARYING PH LEVELS ON THE PHYTOREMEDIATION OF IRON BY WATER HYACINTH (EICHHORNIA CRASSIPES)

Abandoned gold mines in northern Georgia have produced acid mine drainage, thus making iron a freshwater pollutant in Georgia waterways. Acid mine drainage results from exposing pyrite, commonly found in mine tailings, to air and water. The resulting decreased pH increases the solubility of other heavy metal contaminants and can be detrimental to flora and fauna, in addition to contaminating drinking water. Because of this water contamination, this study focuses on the effect pH has on the rate at which water hyacinth (Eichhornia crassipes) is able to phytoremediate iron. We chose pH as an independent variable because we want to determine if the efficiency of phytoremediation can be improved by adjusting the pH. This is a variable that has not been widely reported in the published literature as most studies focus on phytoremediation at a constant pH range. We hypothesize that testing the effectiveness of iron remediation at varying pH levels will be comparable to tests of copper phytoremediation by water hyacinth because of the similar chemical characteristics and behavior of the two metals. Water hyacinths were introduced to different aqueous solutions of 25 ppm of iron that were adjusted to different pH ranges — acidic (3.5 - 3.7), neutral (6.5 - 6.7), and basic (9.5 - 9.7). For each pH range, experiments were run in triplicate. In our previous study with remediating copper using water hyacinth, we found the greatest decrease in metal concentration in the first 20 minutes. Based on these results, we used three sampling time intervals in this investigation – every 5 minutes for the first 40 minutes, every 20 mins for an additional 140 minutes, and once 24 hours after the initial introduction of the plant to the iron solution. The iron concentration of each sample will be determined through visible light spectrophotometry, however, a preliminary visual assessment of the samples indicates that remediation did occur.