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Rx for Action

A blog devoted to helping people find local medicine take-back programs and highlighting current research findings and pending legislation.

BC Sampling03

Pharmaceuticals influence streams for long distances

Wastewater treatment plants (WWTPs) are one of the main sources for pharmaceuticals in the environment. Yet it is unknown how long these pharmaceuticals stick around in rivers or just how far downstream from the treatment plants they travel. A new study by a U.S. Geological Survey (USGS) team took on these questions and also looked at how other emerging contaminates, like fragrances or triclosan, behave in streams.

While it is impossible to tag a piece of water and watch it wash downstream, both stream discharge and transport time (the time it takes a tracing solution such as salt to travel from a WWTP to a downstream point) can be measured. The technique is known as Lagrangian sampling, which relies on following a certain unit of water through a stream. By sampling water at set times and locations, and using collected values and a lot of complicated math, scientists can find out how long water will travel through a stream and how quickly chemicals in the wastewater disappear.

The USGS crew collected water in two streams: an urban stream in Boulder, CO with a fairly large wastewater treatment plant; and a mostly agricultural stream in Ankeny, IA hosting a small wastewater treatment plant. Collections were taken both above and below the WWTPs and at several locations downstream. The downstream locations were chosen based on transport time tests and represent the estimated distance that WWTPs influence stream conditions, roughly between four and five miles. Sampling was done in the spring and summer so that seasonal low stream levels could be measured.

The study revealed that personal care products, such as triclosan and fragrances, were not only present in effluent at the wastewater treatment facility discharge sites, but also in the sample sites far downstream. In general, the chemicals attached themselves to sediment on stream bottoms, but they did not seem to be broken down by biological or chemical processes in the streams. Antibiotics, on the other hand, did breakdown in the stream, but carbamazepine, an anti-seizure medication, was still found even at the farthest sampling point.

The results suggest that some of these emerging contaminates could persist in streams for up to 62 miles below the wastewater treatment plants. This means that aquatic animals are being exposed to these chemicals even far downstream from the WWTPs. And, considering that downstream communities will use the water as their source of drinking water, this new information will be important for water managers to consider.

Barber, L.B., S. H. Keefe, G. K. Brown, E. T. Furlong, J. L. Gray, D. W. Kolpin, M. T. Meyer, M. W. Sandstrom, and S. D. Zaugg. 2013. Persistence and potential effects of complex organic contaminant mixtures in wastewater-impacted streams. Environmental Science and Technology 47: 2177–2188.

Written by Corrie Layfield

Photo: A USGS scientist collecting a water-quality sample from Boulder Creek, CO. Photo credit: Jennifer Beck, USGS


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Posted by Laura Kammin at 1:12PM on 7/11/2013
Categories: Latest Research