Relatively high concentrations of 3,3'-dichlorobiphenyl (PCB-11) have been reported in water and air, and it has been suggested that this compound did not come from commercial PCB products. We report here data on atmospheric partial pressures of PCB-11 and of total PCBs at five sites around the Great Lakes and demonstrate that both total PCBs and PCB-11 track human population density. In addition, we show that with the exception of Chicago, the PCB congener pattern at our sampling sites is best represented by Aroclor 1242; in Chicago, the pattern is best represented by a 1:1 mixture of Aroclors 1242 and 1254. With the possible exception of Sturgeon Point New York, the levels of PCB-11 in air have not changed between January 2004 and December 2007. The source of PCB-11 may be related to yellow pigments, to the degradation of more highly chlorinated PCB congeners, or to both.

A series of experiments were conducted among the laboratories participating in the Integrated Atmospheric Deposition Network (IADN) monitoring program to evaluate comparability of the reported persistent organic pollutant concentrations. This quality assurance activity is essential because a variety of methods are currently used for sample collection, extraction, and analysis by the IADN laboratories. The experiments included analyses of a common reference standard (CRS), analyses of split samples, and analyses of samples collected with co-located samplers at the Point Petre IADN measurement station. The analytes included polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), and polychlorinated biphenyls (PCBs). For virtually all compounds, the laboratories produced generally comparable results for the CRS samples, the split samples and the co-location samples, although some differences were observed. Analysis of the methods may pinpoint areas where variations in the methods will result in the differences observed in the reported data. These differences can be due to the field sampling process, the analytical method, field blank values, or a combination of all these factors. This study points out the importance of QA activities at every step of an environmental monitoring process so that areas where improvements may be needed or where inconsistencies may exist can be identified.

For years, the Illinois Institute of Technology (IIT) at Chicago has served as the only urban sampling site for the Integrated Atmospheric Deposition Network. Atmospheric concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides, and polycyclic aromatic hydrocarbons (PAH) in the vapor phase have been measured at this site every 12 days since 1993. These data have been used as representative urban regional concentrations, but these measurements may not be characteristic of the entire urban region. Thus, a second site at the University of Illinois at Chicago (UIC), which is closer to the downtown area than the IIT site, was operated from February through October 2002 to evaluate the possible urban source-influenced concentrations of these compounds. The average PCB concentrations at UIC are higher than that at IIT by a factor of ∼2; the PCB concentrations range from 670–4,600 pg/m3 at UIC and 310–3,000 pg/m3 at IIT. The pesticide and PAH concentrations at these two sites are in general agreement except for higher aldrin concentrations in some samples at IIT.

The Great Lakes Water Quality Agreement stipulates that the Governments of Canada and the United States are responsible for restoring and maintaining the chemical, physical and biological integrity of the waters of the Great Lakes Basin Ecosystem. Due to varying mandates and areas of expertise, monitoring to assess progress towards this objective is conducted by a multitude of Canadian and U.S. federal and provincial/state agencies, in cooperation with academia and regional authorities. This paper highlights selected long-term monitoring programs and discusses a number of documented ecological changes that indicate the present state of the open and nearshore waters of the Great Lakes.