Correspondence/Rebuttal pubs.acs.org/est
Response to Comment on “Polychlorinated Biphenyls in Tree Bark near Former Manufacturing and Incinerator Facilities in Sauget, Illinois, United States”
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Following our Anniston study, Dr. Ronald Hites, asked for our PCB data which were used in a model to identify source regions. The result was published by Peverly et al.6 Their Figure 3D shows that the model identifies the South Landfill as part of a source area. That finding is clearly a result of the trend shown in Figure 2, ref 1. Recently, Dr. Hites used our Sauget PCB data to identify the source area to our tree bark samples using a model similar to what was used in Peverly et al.6 His conclusion is that the source of PCB to our samples is an area north from the WGK site and north, and downwind, from all of our sample sites (Hites Figure 1, top). The many documents produced from investigations of the Sauget area near WGK show no PCB sources north from the known sites, including Sites P, Q, and R. Based on modeling of PCB emissions from the WGK plant site by Weeks,5 the “far receptor” deposition area would be about 700 m south from the PCB source area identified by Hites. This far receptor corresponds to “Area 1” of soil sampling by USEPA in 2009.4 Hites additionally identifies a site of PCDD/PCDF emissions (his Figure 1 bottom) using data from the same samples.7 In our survey of possible sources of PCDD/PCDF in and around Sauget, nothing appeared in the source area identified by Hites. In a concluding statement, Hites notes that the PCB and PCDD/PCDF source sites in Sauget identified by the model are anomalous. He concludes that the PCB incinerator at WGK, emitting high above ground (height unknown to us and not specified in any literature we have seen) was responsible for distributing PCBs and PCDD/PCDF away from WGK, resulting in the identified source areas in his Figure 1. In fact, we calculated that the PCB incinerator apparently emitted only 5 kg total PCB (from 10 455 mt burned) during 6 years of operation (1971−1977), based on documents regarding incinerator performance that were available to us.3 The incinerator was never a significant source of atmospheric PCBs, a result confirmed by Weeks.5 Emissions of PCDD/ PCDF from this source are not known because measurements were not made at the time. There could have been several PCDD/PCDF sources at WGK: We note that the WGK site had a large coal-burning electric power plant on site well into the 1970s, that could have been a PCDD/PCDF source.7 Again, estimates of emissions and deposition from WGK made by Weeks5 do not show any deposition near the PCDD/PCDF source shown by Hites. The results of tree bark and soil analyses, and emissions estimates from Sauget3−5,7,8 do not suggest a single source of atmospheric PCB or PCDD/PCDF in the area. Instead, the sources of PCB and PCDD/PCDF are a complex of known sites, and some that may yet be unknown, especially
ree bark is a passive collector of atmospheric contaminants, with gas-phase organic compounds dissolving into bark lipids, and those associated with particles captured by the rough texture and high surface area of the bark. There is no “standard” for tree bark so high or low concentrations are based on comparisons to other sites. The results reveal the atmospheric contaminant exposure during the lifetime of the tree, with higher exposures indicating a nearby source. We used this approach when sampling and analyzing tree bark in Anniston, Alabama, the first site of polychlorinated biphenyl (PCB) manufacturing in the U.S.1 PCB results from Anniston showed a very strong and significant decline in tree bark concentrations (a high/low ratio of 4912) with increasing distance (up to 9 km) from the PCB plant site (see Figure 2 in ref 1). This plant site was about 380 m from the largest chemical waste disposal site, known as the South Landfill, on the northern flank of Coldwater Mountain, used for disposal of chemical waste from production at the Anniston Plant. The highest concentrations of ∑PCB in trees in this study were from specimens growing on a floodplain downstream from the South Landfill. Our bark results, and narratives from people living and attending community activities in the area,2 revealed extremely high concentrations of PCBs in bark, soils, and groundwater. The other PCB production site in the U.S. was in Sauget, Illinois at what is now known as the W. G. Krummrich plant (WGK). The WGK plant was large, covering an area of 71 ha (in comparison to 21 ha at Anniston), the result being that, unlike Anniston, the three chemical waste disposal sites used were at a distance up to 1.5 km from the plant. The Sauget site did not have a single atmospheric PCB source, which we observed at Anniston. The PCB waste disposal areas in Sauget are at what are now known as Sites P, Q, and R (see Figure S2 in Hermanson et al.3). The largest of these was Site R, used for PCB and other chemical production waste disposal from 1955 to the end of PCB production in 1977. Site R surface and groundwater drained off site into the Mississippi River taking some PCBs from the area. Analysis of tree bark samples from Sauget showed lower maximum ∑PCB values than in Anniston, likely a result of Site R draining to the river and not to a floodplain. The high/low ratio of ∑PCB concentration in Sauget was 12.5. A “distance vs. concentration” plot was never prepared for Sauget because there was no trend in the data. Instead we found that certain sites other than Site P, at various distances and directions (although mostly to the north) from WGK, showed relatively high PCB concentrations without any apparent single source. We concluded that these results showed emissions from soils near the tree, but how PCBs arrived in those soils is unknown. This conclusion is consistent with ∑PCB data from soils collected north from WGK in 2009 which vary by a factor of 56 over a distance of 225 m.4,5 © 2017 American Chemical Society
Published: June 27, 2017 8206
DOI: 10.1021/acs.est.7b01688 Environ. Sci. Technol. 2017, 51, 8206−8207
Environmental Science & Technology
Correspondence/Rebuttal
considering the geographic variability of tree bark and soil contaminant concentrations in the area.
Mark H. Hermanson* Hermanson & Associates LLC Minneapolis, Minnesota 55419 United States
Richard Hann Norwegian Technical and Natural Sciences University NO-7491 Trondheim, Norway
Glenn W. Johnson
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University of Utah Salt Lake City, Utah 84108 United States
AUTHOR INFORMATION
Corresponding Author
*Phone: 267-207-7895; +47 79023351 (Norway); e-mail
[email protected]. ORCID
Mark H. Hermanson: 0000-0002-3557-523X Notes
The authors declare no competing financial interest.
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REFERENCES
(1) Hermanson, M. H.; Johnson, G. W. Polychlorinated biphenyls in tree bark from a former manufacturing area in Anniston, Alabama. Chemosphere 2007, 68, 191−198. (2) Spears, E. G.. Baptized in PCBs: Race, Pollution, and Justice in an All-American Town; University of North Carolina Press: Chapel Hill, 2014. (3) Hermanson, M. H.; Hann, R.; Johnson, G. W. Polychlorinated biphenyls in tree bark near former manufacturing and incineration facilities in Sauget, Illinois, United States. Environ. Sci. Technol. 2016, 50, 13743−13748. (4) Gonzalez, J.; Fend, L.; Sutherland, A.; Waller, C.; Sok, H.; Hesse, R.; Rosenfeld, P. PCBs and dioxins/furans in attic dust collected near former PCB production and secondary copper facilities in Sauget, IL. Procedia Environ. Sci. 2011, 4, 113−125. (5) Weeks, D. A. Air Modeling Analysis of Potential Historical Releases at W. G. Krummrich Plant, Sauget, IL. Report; Risk Management & Engineering, Ltd.: Garland, TX, January 2011. (6) Peverly, A. A.; Salamova, A.; Hites, R. A. Locating POPs sources with tree bark. Environ. Sci. Technol. 2015, 49, 13743−13748. (7) Hermanson, M. H.; Johnson, G. W. Chlorinated dibenzo-p-dioxin and dibenzofuran congener and homologue distributions in tree bark from Sauget, Illinois, US. Environ. Sci. Technol. 2015, 49, 855−862. (8) Stratton, C. L.; Sosebee, J. B., Jr. PCB and PCT contamination of the environment near sites of manufacture and use. Environ. Sci. Technol. 1976, 10, 1229−1233.
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DOI: 10.1021/acs.est.7b01688 Environ. Sci. Technol. 2017, 51, 8206−8207
