Water: A Fish’s Pharmacy

Written by: Tabitha King

Here you can see Lisa McAnulty and I weighing out sediment to begin the extraction stage of sample processing. We are and will be using an adaptation of a QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) method to process both our sediment and fish tissue samples.

What if I told you fish could potentially be ingesting caffeine, pain medicine, and other pharmaceuticals on a daily basis? You may be wondering how this is possible since fish do not regularly visit the pharmacy to pick up their prescriptions. However, there is a growing concern amongst scientists and other stakeholders that the very medications we are taking (even common allergy relievers) are not being removed during wastewater treatment. Current regulations placed on wastewater treatment plants do not require the removal of such substances. To make matters worse, if a treatment plant was to take on the task of removing pharmaceuticals from their customers’ sewage, there are new compounds made on a daily basis. Each chemical would require a unique form of effective removal to ensure at least a majority is removed before treated water is discharged into local waterways. It is currently not known at what amounts of these medications are making their way into our local waterways and accumulating in aquatic organisms and sediment.

As an Environmental Science major with a concentration in Conservation, I am participating in an OSCAR Summer Team Project investigating the presence of pharmaceutical micropollutants in Hunting Creek and Gunston Cove on the Potomac River.

What exactly is a micropollutant?

Synthetic drugs are designed for people to take a specified dosage for a given ailment. The human body is not able to utilize the entire amount of a given medication (pill, syrup, etc.), and so the remainder is expelled in our waste and flushed. As these chemicals are combined in sewers, pass through wastewater treatment plants, and eventually mix in with freshwater systems, they become diluted and dispersed throughout streams and rivers. However, even a very minute trace of a pharmaceutical can affect aquatic organisms in ways that are not yet entirely known.

My task, along with my partner Lisa McAnulty, is to analyze fish, water, and sediment we collect from the river for 77 chemicals. To accomplish this, my summer research consists of 10 weeks, jam-packed with sample collection on the rivers, laboratory work, and data analysis. Each component of my research has been, accompanied by unique and unexpected events. For example, we wear chest waders on what PEREC (Potomac Environmental Research and Education Center) faculty and students refer to as “fish trips”. These waders are designed to prevent water from coming in contact with your body from the chest down. In order to collect our fish, we hop off the side of the boat into the shallows of designated riverbanks. Two people then stand at opposite ends of a seine net (long and rectangular in shape), and pull it parallel to the shoreline for about 50 feet. The two ends are then brought together so that the fish inside can be identified, measured, and released or kept for later analysis.

Every three tubes of sediment represent three jars of mud taken from specific stations (pinpointed using GPS coordinates) on the Potomac River. These tubes contain mud from Hunting Creek stations located near Alexandria, Virginia across from the National Harbor.

On a separate occasion, I found myself spending an entire day in the SRIF (Shared Research and Instrumentation Facility) laboratory playing with slimy sediment collected from the bottom of the river. My day’s tasks consisted of thawing frozen mud, centrifuging mud, weighing mud, shaking mud, and vortexing mud over 40 times. Through a series of steps, we were able to use the variation of densities of the water, solvent, and sediment to extract our target chemicals. With each additional step of sediment sample processing, we could remove the top (least-dense) layer to concentrate and run through our LC-MS/MS instrument for analysis. On this particular day, a batch of our samples were being processed with samples collected separately as a part of the ongoing PEREC Hunting Creek study that analyzes water and sediment for hundreds of various chemicals annually in recent years.

Two members of our boat crew prepare to tie down the boat at Gunston Cove (near Mason Neck) before we set out on our team’s first fish sampling day.

Before the start of the OSCAR Summer Team Project, I was working in the SRIF lab with Dr. Huff on Mason’s SciTech campus to help process surface water samples collected during the summer of 2016. The water processing protocol was very similar to what is being used in our current OSCAR Summer Team Project, which allowed me to become familiar with the procedure ahead of time. Between sampling seasons, I also helped with the preparation of stock solutions of most of our target chemicals. This is essentially the first step in preparing the LC-MS/MS machine for detecting these compounds in actual samples collected in the field. From these stock solutions, the machine can be tuned and calibrated to recognize the unique ionic features of each target chemical. Stock solutions are also be combined with each other to create working mixes and surrogate standards to be added to samples to test how well our technique recovers the initial amount of each chemical in our samples. All of these preparatory steps for our project gave me insight into research method development. Many of the 77 chemicals being investigated this summer have not been looked at yet in the ongoing PEREC Hunting Creek study, but will be incorporated into the research from now on.

While the presence of these target chemicals is potentially detrimental to aquatic ecosystems, being able to successfully detect and quantify them would bring policies one step closer to updating current wastewater treatment regulations. You can follow our progress and see the results of our analysis, on George Mason University’s Potomac Environmental Research Center blog.


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