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E-M:/ Mysterious peaks in chemicals showing up in Great Lakes

Title: Mysterious peaks in chemicals showing up in Great Lake
Science News - December 11, 2003

Data reveals pulses of banned POPs

Mysterious sources of banned compounds, such as PCBs, are causing peaks in  air concentrations over the Great Lakes every six years, according to a novel  analysis of long-term air quality data posted to ES&T 's Research  ASAP website today ( 10.1021/es034699v ).  The study, conducted by Stephanie Buehler, Ilora Basu, and Ron Hites from Indiana  University, raises questions about whether more effort is needed to stop PCBs  from escaping into the environment.
Buehler and colleagues used data collected by the Integrated Atmospheric Deposition  Network (IADN), a joint U.S.-Canadian venture on the Great Lakes ( Environ.  Sci. Technol .2002 ,36 ,354A-359A ).  An earlier study with these data showed that PCB concentrations in the air around  the Great Lakes were declining and that the amount of pollutants deposited in  the lakes was less than the amount that volatilized into the atmosphere. "But  we could still see periodicity in the data and were curious about other effects  that could cause the air concentrations to change," Hites says.


 ...provided a rigorous way to look at periodicity in long-term  data sets, Hites explains. The analysis showed that both PCBs and the banned fungicide  hexachlorobenzene have peak concentrations in the air over the Great Lakes roughly  every six years, Buehler says. The increase was especially noticeable in 1998  and 1999, Hites adds.