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It is not clear whether changes in mercury input will result in a linear change in mercury methylation [i.e., creating MeHg]. Computer models, such as one developed for the Florida Everglades, tend to predict a linear response, but there are little data to support the predictions…Chicago Tribune: Some recent research suggests that mercury levels in fish can drop significantly once emissions from nearby sources of the metal are reduced. For instance, after Florida imposed tough regulations on waste incinerators, the top source of mercury in that state, levels of the metal in largemouth bass and wading birds in the Everglades dropped more than 60 percent. The Blagojevich administration thinks the same thing could happen in Illinois, since about two-thirds of the mercury that falls in the state is estimated to come from coal plants and other sources within state borders. (January 5, 2006) Garbage in, Garbage out
Response:  Such unfounded claims are based almost exclusively on speculative computer modeling, not empirical findings. Secs. 5, 15 and 16 present the case that cutting all man-made sources of Hg emissions within Illinois would not change MeHg levels in albacore, yellowfin, skipjack tuna, sword fish, orange roughy, grouper, walleye or salmon consumed in Chicago. We refer again to the scientifically defensible work of the Illinois State Water Survey office which found that, “The hypothesis that most Hg in Illinois and the USA soils is of anthropogenic origin is rejected."To add context for Illinois deposition rates, total mercury deposition in the U.S. from emissions originating from U.S. utility generators has been estimated at 13.5 tons in 2001 (Fig. 21-A). This amount pales compared to the estimated deposition of 327 tons originating outside the U.S. and the naturally occurring amounts in situ available from aquatic and geological reservoirs. As is the case in Illinois, neither total mercury deposition nor total system burden is measured across the U.S. A Vital Need for Essential Answers
Before issuing costly state targeted mandates of 80 to 90% Hg reductions, it seems responsible for Illinois regulatory authorities to answer some fundamental questions regarding perceived objectives and methodology for targeted outcomes; similar questions should be required collectively or individually from Connecticut, Massachusetts, Minnesota, New Hampshire, New Jersey, North Carolina and Wisconsin, so say nothing of EPA itself. Put simply, what gain for all the pain? • How much total mercury is deposited and in situ within Illinois? Let’s examine in more detail the reliability of the rather affirmative premises for State action as reported by the CT (January 5, 2006). The two major premises are: (1) "About two-thirds of the mercury that falls in the state is estimated to come from coal plants and other sources within state borders,” and Illinois Hot Spots?
It appears the CT source material for these premises is the December 2003 Environmental Defense (ED) publication, "Out of Control and Close to Home." It states: "Local emissions of mercury are largely responsible for mercury deposition hot spots (locations where mercury deposition is high), providing an excellent opportunity for effective reductions. [A claim contradicted by results in Fig. 21-A] Recent modeling [by EPA's Dwight Atkinson whose results are shown and clarified in Fig. 21-B] suggests that at mercury hot spots pollution sources within the state can account for large portions of the deposition (Figure B). [Note: Figure B of the ED report shows the "top 8 worst hot spot states" in the order of MI, MD, FL, IL, SC, NC, PA and TX.] At hot spots across the United States, local sources often account for 50% to 80% of the mercury deposition. As shown in Figure B, for example, local pollution sources account for over 60% of the deposition in hot spots in Michigan, Maryland, Florida, and Illinois. [Confirmed to be 63% in the single (!) hot spot centered on the Chicago area clarified in Fig. 21-B] In another recent analysis in south Florida, dramatic reductions in mercury pollution from local incinerators were accompanied by a lowering of mercury concentrations in large mouth bass by 60-75%, indicating the importance of controlling local sources to reduce local contamination." (Emphases and [comments] added)  ED has relied on the modeling efforts distributed by EPA’s Dwight Atkinson. Another computer modeling analysis was carried out by Dr. Mark Cohen of the NOAA Air Resources Laboratory at Silver Spring, MD. However, to date, no credible simulations are suggesting that two-thirds of Illinois mercury deposition originates from in-state emissions sources. We say “no credible” quantification because Dr. Cohen's model assumed only man-made sources of mercury from U.S. and Canada is emitted into the modeled atmosphere. This is of course dubious because such a first-step assumption inexplicably and unjustifiably ignores enormous sources of atmospheric mercury from (1) other anthropogenic emissions, principally Asian (2) re-emissions from natural sources within the U.S. and Canada (see Fig. 5-B) and (3) other world-wide natural emissions from volcanoes and geological and oceanic reservoirs (see Fig. 5-A). Thus, it seems highly problematic to assert that any mercury emission cuts by the state of Illinois will lead to significant reductions in the deposition of mercury to Illinois soil and waters, the Great Lakes area or even regions further away. Fig. 21-B clarifies the misleading claim that two-thirds of Illinois deposition originates from in-state anthropogenic emissions. As shown in Atkinson’s re-scaled model, there is essentially only a single “hot spot” in Illinois, around Chicago (top left). Even this result may simply be an artifact of EPA’s model assumptions which may over-prescribe the role of dry atmospheric deposition relative to wet deposition. Other parts of the state are less impacted because about 81% of Illinois emissions are transported out of the modeling domain.  Even according to Atkinson’s results, only a tiny amount (i.e., 63 kg or no more than 0.1%) of Illinois' annual Hg emissions fall back to the Great Lakes. Also consider that only a fraction of that amount may be transformed into MeHg. This all raises serious doubts about claims for MeHg reductions in Great Lakes fish, even if Illinois emitted zero mercury from its coal-fired power generation plants. Swamped in Florida
What about the seemingly encouraging news for Illinois from the Florida Everglades study (i.e., the expectation that lowering mercury emissions from Illinois power plants can lead to a substantial reduction of MeHg in locally caught fish)? On p.12 of "Out of Control and Close to Home," ED states: "An ambitious analysis of mercury pollution, deposition and fish contamination in Florida provide on-the-ground evidence that corroborates the importance of local sources. Because of tighter standards on medical and municipal waste incinerators that took effect in mid-1992, South Florida's total estimated local emissions of mercury declined by about 93% between 1991 and 2000. During this same period, mercury deposited via rain and other precipitation declined in South Florida by about 25%. Concentrations of mercury in largemouth bass have also decreased significantly, 60-75% since the early 1990s. The data strongly suggest that reducing local mercury pollution will lower concentrations in local water bodies, and in turn reduce contamination in fish and the risk of human exposure." The “strong suggestion” is in serious doubt. A distinguished team of researchers led by the University of Maryland’s R. Mason recently issued a warning to decision makers’ about reliance upon unproven modeling efforts, such as in the Florida Everglades:
Mason’s warning seems to have proven out for Florida, raising serious questions about ED’s interpretations of the data. Has local deposition actually diminished in response to local emissions reductions? The answer is no. First, there was a sharp drop (Fig. 21-C) in mercury emissions from medical waste facilities from 1991 to about 1997. But a key question is, if the MeHg content in largemouth bass from the Everglades really decreased as an instantaneous consequence of the decline in south Florida medical waste emissions as described by ED, then prior to that time (between 1980 and 1991) when emissions were dramatically increasing did anyone report correlated large increases in MeHg levels for largemouth bass, or any area predator fish species? Secondly, recent wet deposition data from three Florida monitoring sites including the Florida Everglades (Fig. 21-D) strongly suggest that the sharp fluctuations over time are not consistent with or correlated to trends for industrial Hg emissions in South Florida. Note that deposition rates returned to sharply higher levels in 2003. Thus, the “hot spot” remediation hypothesis for South Florida as claimed by ED is neither convincing nor proven. This poses several questions for policy makers. First, if, as claimed, MeHg levels in largemouth bass declined in response to a mandated reduction of industrial emissions (Fig. 21-C), have mercury levels now sharply increased in any predatory fish in concert with the dramatic rebound in deposition rates (Fig. 21-D)? Secondly, if local emissions and deposition rates actually are tightly correlated, does the 2003 rebound in deposition (Fig. 21-D) point to a return of higher local man-made emissions? In other words, what’s again firing up the “hot spot” in the absence of those sharply curtailed incinerator emissions (Fig. 21-C)? Another puzzle is worth considering. Florida is ranked only 18th nationally in Hg emissions (about 1 ton) from coal-fired power plants, yet the levels of Hg wet deposited at several locations in Florida are among the highest in the U.S. By comparison, Texas ranks first nationally (5 tons), yet its Hg wet deposition rates are neither high nor especially alarming (Fig. 21-E). Also, the biggest signal in these data is a sharp decline in Hg wet deposition from the Gulf Coast to the Canadian border. The highest values are along the Gulf Coast, not in the Ohio Valley where coal-fired power plants are abundant. This further undermines ED’s “strong suggestion” that local emissions reductions guarantee consistent local deposition control. Contrary to ED’s assertions, when chemical, meteorological and climatic processes are accounted for, evidence is stronger that significant Everglades’s deposition sources are foreign, out of state and/or natural within the state. Another ED misstep is discounting the complexity of the cycling process for various species of mercury, especially methyl mercury. (See Sec. 5) It is well known that municipal and waste incinerators release mostly the oxidized or ionic form of mercury, which is water-soluble and easily rain-washed out into local rivers and lakes.  By contrast, elemental mercury emitted from coal-fired plants is not readily water-soluble. Also, power plant chimneys are typically higher than incinerator chimneys, generally aiding in wider dispersal away from a local point of origin. Conclusion
In conclusion, the proposed policy action by Illinois appears hasty, unscientific and ill-advised, apparently fueled by confusion and misinformation. There appears no convincing evidence for sketching a scenario whereby a mandated lowering of Illinois industrial Hg emissions would ultimately improve human health through a concomitant lowering of MeHg in local fish, let alone imported sea foods. Sadly, the most likely result will be a spectrum of unintended negative consequences, resulting in severely diminished public health and wellbeing. |
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“It is not clear whether changes in mercury input will result in a linear change in mercury methylation [i.e., creating MeHg]. Computer models, such as one developed for the Florida Everglades, tend to predict a linear response, but there are little data to support the predictions…. [D]ecision makers need more than mercury concentrations to be able to ensure defensible interpretation of the indicators, such as MeHg in fish. Other necessary information includes land use; food-web structure; the introduction of exotic species; point-source discharges; changes in climate, atmospheric chemistry, and acidic deposition; and hydrological regimes (e.g., retention time and water level fluctuation). ... Other factors, such as sulfate and organic matter that impact bacterial activity, could also possibly cause an increase in fish mercury concentration even as atmospheric deposition decreases.” [Emphasis added]| < Prev | Next > |
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