Click on the image below to listen to the Academy's Dr. Ruth Patrick, recipient of the National Medal of Science, describe the importance of protecting the water of the Schuylkill River.

The Philadelphia Water Department does thousands of tests on the water that gets pumped from the Schuylkill to drinking water treatment plants every year, but Academy scientists have been studying the river below the Fairmount Dam to get a picture of what effect water from the Schuylkill may be having on the Delaware Estuary. The goal of their research is to better understand what pollutants are getting into the river and what happens to them as they move farther downstream.

"The river below the waterworks is very different from the part above the dam," says Dr. David Velinsky, "because there is very little natural riverbank, there’s a lot of industry, and it’s subject to tides. This section of the Schuylkill has never been studied this closely before. What happens along here can have serious implications for the Delaware Estuary."

Dr. Velinksy and his team have been collecting water samples at various stations along the river every month for the past two years. "It’s important to gather data over a long term, rather than take a single snapshot," says Dr. Velinsky, "because a river is constantly subject to change." There are all kinds of seasonal variations and things like floods, dry spells, and snow storms all affect what scientists find at any given time.

"One of the purposes of this project is to try to document what they call biogeochemical changes of nutrients and trace metals that are flowing from the urban environment into the tidal Schuylkill and into the Delaware Estuary," says Dr. Velinsky.

While scientists understand many of the processes that occur as these materials cycle through the river, they want to measure specific parameters such as nitrate, ammonia, and chlorophyll a to determine what is taking place at different times of the year. This information will help in the development of a water quality model and enable managers to set targets for things like total nutrient load.

Using miskin bottles, filtering devices, and cutting-edge clean sampling methods, scientists collect samples from various parts of the river.

Samples are returned to the lab for analysis using some very sophisticated equipment:

• Nutrients such as ammonia, nitrate, and phosphorous are measured on a continuous flow nutrient analyzer.
• Trace metals such as zinc, lead, and copper are measured on an Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) system.
• A Flourometer is used to measure chlorophyll a.

So, scientists have collected samples, analyzed them with expensive equipment, and come up with computer generated numbers and graphs. Then what do they do?

"We try to look at the data in a total framework," says Dr. Velinsky, "so we can make some assessments about what is actually happening out there in the Schuylkill. What are some of the processes that are affecting nutrients and trace metals in the river?" Researchers like Dr. Velinsky use a variety of techniques, such as spreadsheets and graphical interfaces, to visualize the system and compare what their monitoring data shows to the chemical and biological processes that they would expect to occur.

Looking carefully at a graph of chlorophyll a, says Dr. Velinsky, reveals that there was a significant bloom of phytoplankton in June, 2000, around the Walnut Street bridge. "As a result of a higher algal biomass (more algae)," says Dr. Velinsky, "one would expect that the nutrient uptake would be greater. That should actually lower the nutrient levels we find as we move down the river." Lower levels of nutrients downstream in the same time period, (June 2000), is exactly what researchers found.

By looking at the tidal Schuylkill over a long term, researchers are seeing the inputs of and changes brought about by nutrients, chemicals, and metals from throughout the watershed. "The real value of these long term studies," says Dr. Velinsky, "is that we can determine the processes that are going on in amongst the noise of daily and seasonal changes to the watershed. Once we know the ecological impacts of nutrients and trace metals on this system, we can take a holistic approach that considers the entire watershed. Ultimately, we want to better manage the sources to lessen the impact."

In the end, Dr. Velinsky reminds us, we all play a role. "Everybody has an effect," he says, "from throwing trash on the street to flushing their toilet, to spending time in their cars. Anything we do in the upper watershed will have some impact on this tidal part of the river, because all that material makes its way down here in some way, shape, or form. And from here, it goes right on to the Delaware Estuary and eventually out to the sea..."

Click on the image below to see Dr. Velinsky on the Schuylkill, describing how various activities in the watershed affect the Delaware Estuary.