Use of sulfur-oxidizing bacteria for assessment of chromium-contaminated soil

摘要

In recent years, biological toxicity tests have been conducted for soil assessment of environmental pollutants to evaluate the environmental risk due to heavy metals. In this study, batch tests were conducted with soils contaminated with hexavalent chromium (Cr~(6+)) using sulfur-oxidizing bacteria (SOB). For control soils (without Cr~(6+)), the electrical conductivity (EC) increased linearly over time in all samples, indicating that no toxic substances were present in the soil. The initial EC varied between 6 and 7.8 mS/cm, and the final EC varied between 22 and 27 mS/cm after incubation for 65 h. For batch tests performed using Cr~(6+)-contaminated soil, the EC increased slightly or remained stable in all the test samples after a few hours. Thus, the presence of toxic substance Cr~(6+) inhibited the SOB, which leads to no sulfuric acid formation and therefore, no change in EC. These results indicated that SOB can be employed as a test microorganism to assess the quality of heavy metal-contaminated soils.