Tuesday Talk explores themes of caves and water sources

​University and research coordinator Sarah Bartle spoke to Chincoteague Bay Field Station staff, students currently taking college courses and professors teaching those courses on Tuesday evening about her research titled “Tracing Methods to Identify Recharge Sources and Quantify Discharge from a Submerged Spring.”
 
Sarah’s research began in 2011 at Shippensburg University, and it is still currently being conducted. To begin her presentation, she showed different examples of caves including carbonate, gypsum, quartz and marble, halite and wild caves.
 
She also explained how people’s fears of caves have changed over time. For example, people used to believe salamanders were actually baby dragons that lived in caves. Now, people are afraid of bats living in caves.
 
The significance of her research was that there is a lot of non-point source pollution in environments which means there is pollution that has no known source. Conduit streams which flow through caves have short residence times, or times that material is flowing through them, and they do not have enough time to get rid of the toxins that are flowing through. This also makes it difficult to know who is to blame for the toxins in the water.
 
For her research, Sarah mainly looked at Welsh Run where the stream seemed to trail off underground at one point and suddenly a spring appeared at another point. Sarah and her research group used dye dilution by time to determine the quantity of the sources of water that led to the spring.
 
“What goes down must come up again. So, if it goes underground, the water, the losing stream, it has to come back out at a spring and usually into a stream,” Sarah said.
 
The purpose of her research was to identify methods of locating connections between surface water and ground water and to find out if there are one or many sources that are contributing. She became interested in studying Welsh Run because there were cave fish, or surface fish, that were only there in the winter and not during the summer.
 
The group put Sulforhodamine B, or SRB, which is a non-toxic dye, into the stream that was detected on charcoal bags that were set up. This was used to determine if the stream flowed through the cave and out to the spring. The results were successful.
 
“That was a pretty good indicator that our hypothesis was correct that that little stream that was losing went to the cave and then to the spring,” Sarah said.
 
After, Sarah and her group did discharge measurement to figure out how much water was being lost in the stream swallet. The flow conditions played a large factor, and up to 50 percent of the water that was flowing through the cave was not from the stream swallet. The water could have been coming from a pond nearby.
 
The biological study found that the Welsh Run stream had a lot of algae, the pond had a lot of diatoms and the cave had both algae and diatoms. Because of this, her group continued on with the dye trace.
Sarah dumped the dye into the stream and an automatic water sampler was set up at the spring to take samples every 15 minutes. This found the quantity of water in the spring that came from the stream that flowed through the cave and out to the spring.
 
“[The study] showed a lot about how every site is site specific so it showed a lot about different methods you can use to trace water and determine sources based on quantity of water,” Sarah said.