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No description available.

Enzymes react quickly to environmental stress and can serve as sensitive indicators of environmental change. Microbial enzyme activities (MEA’s) can be a useful tool to evaluate the health of an aquatic ecosystem. In this study we compared the trends of MEA’s (µg/g) to total and fecal coliform concentrations (CFU/g) in sediments from a stream in Northeast Tennessee that had an approved fecal coliform Total Maximum Daily Load (TMDL). The comparisons were based on season and land use through which the stream flowed. Triplicate grab samples of stream sediments were collected monthly for 29 months at 14 sites located in agricultural, urban, and forest regions. Dehydrogenase, acid phosphatase, alkaline phosphatase, galactosidase and glucosidase activities were determined using specific colorimetric analyses. Total coliforms and fecal coliforms were determined using the membrane filtration method. There was significant positive correlation (p<0.05 Pearson) between the total coliform concentrations and all five enzyme activities in the winter (January, February and March). A positive correlation was also seen with alkaline phosphatase in the summer. Fecal coliform concentration was positively correlated with dehydrogenase activity in the winter and spring (April, May and June), and with galactosidase activity in the winter, spring and summer (July, August and September). Fecal coliforms were also positively correlated with acid phosphatase in the summer. Only those sediments located in the urban region showed a positive correlation between total coliforms and dehydrogenase, acid phosphatase, alkaline phosphatase and glucosidase. DHA also showed a positive correlation between total coliforms and the forest region. The only correlation between fecal coliforms and region was with acid phosphatase in the urban region. A strong inverse relationship existed with the ratio of each specific MEA over the fecal coliform concentration versus both the seasons and regions. These correlations show that elevated activities of these five microbial enzymes can serve as another indicator of stream impairment.

A total maximum daily load (TMDL), which is the calculated total amount of pollutant that a waterbody can receive from point and non-point sources, is established for streams that do not meet their designated use criteria. Physical, chemical, and biological water quality parameters are used to attempt to identify pollution sources. Microbial enzyme activity (mg/mL) is used to monitor the changes in the microbial community by identifying changes in their metabolism. The health of a stream can be monitored by the presence and absence of microorganisms due to the response of the microbial community to prolonged pollution exposure. To fully understand the metabolic activity, MEA data are compared to other factors including biochemical oxygen demand (BOD), nitrogen, phosphate, total coliform and Escherichia coli concentrations. Dissolved oxygen refers to the amount of oxygen used by microorganisms to degrade organic carbon, which reduces the survivability of aerobic organisms. Nitrogen and phosphate compounds from anthropogenic sources are readily dissolved into water and are limiting nutrients for microorganisms. Total coliforms and E. coli determine the fecal contamination in the waterbody. All of these factors are used to determine point and nonpoint pollution sources. From February 2014 to January 2016, water and sediment samples were collected monthly from 16 sites along Sinking Creek in Northeast Tennessee. During the two-year study, physical and field parameters were measured. Water samples were analyzed for chemical parameters including alkalinity, hardness, and BOD. Using an ion chromatograph, the concentration of phosphates and nitrates in the samples was measured. For biological parameters, the water sample was used to obtain total coliform and E. coli data using the Colilert enzyme substrate test. MEA data were collected from triplicate sediment samples collected at each site. These sediment samples were tested for acid and alkaline phosphatase, glucosidase, galactosidase, and dehydrogenase enzymes. The substrate for these enzymes was added to the respective sample, incubated for approximately 24 hours, and analyzed by colorimetric spectrophotometry to obtain absorbance. The enzyme concentration was calculated by comparing the absorbance to a generated standard curve. The results for the measured parameters were compared to identify correlation between the MEA concentrations and other biological and chemical parameters. The microbial activity should show a holistic view of changes in the waterbody, which should correlate with the other factors. A direct relationship between E. coli, total coliforms, nitrate, phosphate concentrations, and MEAs was expected. A correlation should be seen between MEAs and BOD data, due to an increase in oxygen demand during microbial metabolism. By examining multiple parameters together, the results would provide the necessary information to determine remediation efforts for the waterbody.