Have you ever wondered what the marsh was like many years ago? Probably not, but we (scientists) have a way of determining how much sediment has been collected on the marsh surface over long periods of time (also known as accretion). Recently, we collected three sediment cores within the St. Jones Reserve as part of a long term bio-monitoring project. In order to collect these cores, we used a large tri-pod to help pull up a PVC pipe that was pushed into the marsh to collect and hold the sample. This may sound simple, but there needs to be the right amount of suction to keep the core sample inside of the PVC pipe as we lift it up. Sometimes this process can take multiple tries! After each core is collected we put rubber caps on each end until the soil sample is ready to be processed. Analyses of these core samples for lead-210 and cesium-137 helps determine accretion rates and the age of various depths within the sediment over the past 50-100 years.
Processing the cores can be a messy and smelly job, but it is fun to work with marsh mud. Thankfully, we can open the windows to help reduce the smell. The first part of the processing requires the sediment core to be cut up into 2cm sections and dried in a scientific oven. Then the samples are sent to the University of Delaware campus in Lewes, DE for the final analysis.