An Analysis of Microbial Life and the Effects on Water Chemistry and Microenvironment In a Karst Spring, Southern Eddy County, New Mexico

Several springs found in southern Eddy County, New Mexico, seem to produce hydrogen sulfide, as evidenced by the ‘rotten egg' odor observed near them. The water and sediments downstream from one of these springs were analyzed in an attempt to determine the source of the hydrogen sulfide. Water chemistry and culturing to test for sulfur-oxidizing bacteria were performed.

Dissolved oxygen, pH, hydrogen sulfide, sulfate, alkalinity, and hardness were tested at six locations downstream from the spring. At each location, a sample of the water and a sample of filaments or growth on the stream bottom were taken and analyzed for bacteria.

Bacteria were plated according to different growth media and observed to determine if bacteria existed within the stream at the six locations. Tests were performed to determine what type or types of bacteria were present in the stream.

Colonies from the plating demonstrated increasing bacterial growth downstream from the vent region to the end of the studied portion of the stream. Chemical tests, as well as analysis of the plated bacteria, indicate that sulfate-reducing bacteria are utilizing sulfates in the spring water, resulting in the production of hydrogen sulfide.