Chester River Ponar Grabs: Two GIS Interns Playing in the Mud
by Katherine Wares and Cara Murray
This past Thursday, we had the opportunity to assist on a field trip to map out contamination in the Chester River sediments and resident benthic organisms with Washington College Professor Dr. Kehm and CES Fellow Dr. Krahforst. We cruised down the Chester River using a NOAA chart and a hand-held GPS to guide us and record our collection sites which, for today, were in the Langford Creek area. (See circled area on the chart below.)
Before reaching our destination we stopped at an outcrop along the banks of the Chester River to see a fascinating outcrop of what we think is the Columbia aquifer. What was particularly interesting about this site is the groundwater discharge between bottom of this outcrop and a thick clay layer visibly entering the Chester. Afterwards, we reached the Langford Creek area and meandered up its various reaches, taking sediment grabs from as far up the various creeks as our boat would take us. At each stop we recorded the coordinates of the site and time of the grab and any important observations of the area as well as any significant characteristics of the sediment sample. After a successful grab we collected samples of the surface layer of the sediment (< 2 cm) as
well as any organisms found in the grab. We encounter a number of schooling
fish (either spot or menhaden, we think) in the shallow reaches of the upper
creeks and some ctenophores (cone jellyfish) that got trapped in our “sediment
grab” (which is called a Ponar Grab) in the lower reaches of Langford Creek.
During our trip we managed to see a lot of the wildlife the Chester River area has to offer including ospreys, a bald eagle, and blue herons. While at times we almost got stuck in the mud due to low tide, and some of us lacked the knack for getting a proper Ponar grab, we finished our journey with thirty-two more sediment samples to the cause and some great stories.