|
PROJECT DESCRIPTIONS Changes in Carbon Dioxide Concentration in Headwater Streams Garrecht Metzger, an Earth and Environmental Science major (class of
2009), studied the flux of carbon dioxide from first-order streams in
northern Greenville County, including a small stream in the Furman Forest.
In collaboration with Dr. Brannon Andersen (Earth and Environmental
Sciences Department) and Dr. Greg Lewis (Biology Department), Garrecht
collected water samples along stream transects and measured conductivity,
pH, dissolved oxygen, temperature, and concentrations of major ions
and dissolved organic carbon. The partial pressure of CO2 (pCO2) was
highest at the source spring in all streams and was between 141 to 3317
times atmospheric pCO2. This CO2 probably originated from respiration
by soil biota. Concentrations of CO2 declined rapidly downstream, faster
in forest streams than in urban streams. Modeling conducted by Garrecht
suggests that out-gassing of CO2 from the stream water to the atmosphere
could account for most of the observed decline in stream pCO2. These
headwater streams may be important biogeochemical "hotspots"
for CO2 degassing within watersheds.
Emily Tripp, a Biology major (class of 2010), studied the occurrence
of antibiotic-resistant bacteria (ARB) in streams draining watersheds
with predominantly urban or forest land cover beginning in the summer
of 2009. This research was conducted under the supervision of Drs. Greg
Lewis and Min-Ken Liao. Other Furman students involved in the project
included Jordan Lyerly and Steve McCauley (both class of 2012). Two
streams at the Blue Wall Preserve were among the forest streams sampled.
We quantified abundances of ARB from streams in 5 watersheds with mostly
commercial land cover, 5 watersheds with mostly residential land cover,
and 5 watersheds with mostly forest cover. Water samples were filtered
through 0.45 µm membranes that were placed on nutrient agar with
different antibiotics, and the numbers of bacterial colonies on filters
were determined. Concentrations of fecal indicator bacteria and major
stream solutes also were determined for all samples. Bacteria resistant
to ampicillin, chloramphenicol, kanamycin, and tetracycline were most
abundant in commercial watersheds. With the exception of tetracycline-resistant
bacteria, ARB were least abundant in forest streams. Streams draining
commercial watersheds also had higher electrical conductivity and sulfate
concentrations than did streams in residential or forested watersheds.
In all samples, ampicillin-resistant bacteria were more abundant than
were other ARB by up to 5 orders of magnitude. Our research suggests
that urban streams often have higher abundance of ARB than do forest
streams.
|
 
|