Safe to say, Marsha Black has made some rather important discoveries during her accomplished scientific career.

She’s published groundbreaking research on the impact of pharmaceutical drugs on the ecological health of our waterways, and her work is helping to connect the dots regarding the impact of industrial sites on downstream pollution.

For all of those remarkable discoveries, however, it’s the potential cumulative impact of all her findings that gives her the most concern.

“What is the joint effect of all these chemicals we’re putting in the water?” said Black, an associate  professor in Environmental Health Science with the University of Georgia’s College of Public Health. “We’re running laboratory tests with one chemical, maybe two. We have no clue what will happen if you add Prozac to the heavy metals like zinc, copper and cadmium.”

For her, the best way to begin to answer that question is through methodical studies, sifting through her research and data to find those tiny threats to our water supplies. In some instances, such as her work with pharmaceuticals, those contaminants sometimes defy the traditional notion of what a pollutant is.

What Black and her team uncovered was that minute accumulations of Prozac and Zoloft were making their way through wastewater treatment facilities and into the water. The initial tests were conducted on water fleas, and they didn’t reveal any worrisome signs.

Likewise, tests on mosquito fish yielded results that were expected in that the fish grew lethargic under heavy dosage. However, when the focus shifted to the African clawed frog, Black found that the presence of even the smallest amounts of anti-depressants had the potential to undermine the ecosystem.  The frogs simply ate less and, because they ate less, they were significantly smaller.

“This is significant because when the frogs are smaller, it takes a smaller organism to eat them,” she said. “They have an increased susceptibility to predators. A smaller size also typically means fewer mates and fewer progeny. Needless to say, size is an important thing in the animal world.”

Another study offered a glimpse of a possible connection between land use and river contamination. Long regarded as one of the cleanest water systems in the region, the Altamaha River recently drew the interest of state regulators in Georgia after the system’s mussel population, once very robust, began to decline.

Mussels are recognized as a sentinel species in that they have the ability to offer a glimpse into the environmental health of their geographic surroundings. They live in the water for the entire duration of their life span, processing hundreds of gallons of water per day, meaning they have the potential to accumulate chemicals and pathogens that exist in the water.

Black focused her study on finding trace metals in Asian clams, an invasive, non-native species, and she started in the Oconee River and worked her way south to where the Altamaha enters the Atlantic Ocean in South Georgia.

Their findings weren’t surprising, but they were somewhat alarming. In areas downstream of industrial sites, there were instances of elevated minerals. For example, in Little Commissioner’s Creek just below a kaolin processing facility, there were elevated levels of cadmium, copper and mercury. Downstream from a tire plant, there were higher levels of zinc, while increased levels of chromium were downstream from a nuclear power plant and paper mill.

Black said there wasn’t enough evidence to directly connect the higher levels to their proximity to the industrial sites, but it was a logical assumption. “We do not have proof obviously but, where we find (these minerals is) downstream of these places,” she said.

“We don’t find them upstream, so ergo, the assumption is that some part of their process contributed to the elevated levels in the sediments.”

In addition, the research yielded a new process of using statistical procedures that was able to distinguish the metal levels in the sediments and mussels from the natural contributions to the river from bed rock and soils.

The data gathered from those experiments proved invaluable to the Georgia Environmental Protection Division, and one of her upcoming projects promises to offer more vital information to policymakers.  Working with other researchers, Black obtained funding from the Georgia Sea Grant Program to examine the state’s coastal waters and the influence of leaking septic tanks on water quality.

Black said her team recently put out “spat sticks,” which are PVC rods that are coated in concrete and will attract colonies of oysters. While the oysters will be able to show signs of accumulations of certain pharmaceuticals, the research will also enable scientists to track what types of bacteria and viruses are seeping into the coastal waters as a result of septic contamination.

“The notion is that if these oysters accumulate (sufficient amounts) over time, that perhaps this method  could be used as a remediation tool,” Black said. “It’s not going to work in large bodies of water, but maybe in small tidal creeks it could.”

While each new discovery made by Black and her colleagues reveals new information to be used, the real challenge is connecting those seemingly unconnected findings to help paint a broad picture of the health of   our water systems. Being able to piece that puzzle together is crucial for other scientists, as well as  policymakers, as they work to keep our waterways safe.

“That to me is the biggest problem and, scientifically, that’s the more difficult one to solve because there   are infinite combinations of contaminants,” she said. “It’s difficult to put your finger on what causes what, but, (if you’re a regulator), you do want to put your finger on it because then you can go back and regulate the substance better. Teasing that information out of these studies is very difficult, but it’s something we have to do.”

– Johnathan McGinty

Posted April 25, 2011.