ES&T’s Best Papers of 2006
n 2006, ES&T published nearly 1100 papers on a wide range of topics. But which ones were the top papers—the best of the year? Our associate editors and assistant editor nominated papers that they felt were of the highest caliber—those expected to make a large and long-lasting impact on the field. I chose a subcommittee from our editorial advisory board to pore over the nominations and narrow the list to about five papers in each category: environmental science, policy, and technology. As Editor-in-Chief, I had the Solomon’s task of trying to choose the best among the best. We hope this is a way to bring special recognition to you, our authors, and focus attention on your high-quality papers. The Best Paper Awards are an annual event announced online in February or March of the following year. Each author receives a certificate of award and our heartiest congratulations. —JERALD L. SCHNOOR
Courtesy of Meg L ayese
ENVIRONMENTAL SCIENCE Top paper: Foundations of mercury in the environment
“Complexation of Mercury(II) in Soil Organic Mat ter: EXAFS Evidence for Linear Two-Coordination with Reduced Sulfur Groups” by Ulf Skyllberg and Jin Qian, Department of Forest Ecology, Swedish University of Agricultural Sciences; Paul R. Bloom and Chung-Min Lin, Department of Soil, Water and Climate, University of Minnesota, St. Paul; and William F. Bleam, Department of Soil Science, University of Wisconsin, Madison, 2006, 40 (13), 4174–4180. Ulf Skyllberg says it felt as though he did not sleep during the entire week that he and his colleagues collected the initial data that eventually became the basis for their winning ES&T paper. Their results, which show how mercury binds to natural organic matter (NOM), have the potential to trickle through the entire mercury community. Ensconced at the Brookhaven National Laboratory in 1999, Skyllberg spent days tending to the extended X-ray absorption fine structure (EXAFS) synchrotron machinery, which the team used to analyze samples from forest peatlands in Minnesota. Skyllberg had worked in Paul Bloom’s lab at the University of Minnesota, St. Paul, as a postdoctoral fellow in 1995–1996. He made the temporary move from Sweden with the intention to study aluminum in soils. Instead, Bloom persuaded him that mercury 2080 n EnVIronmental Science & Technology / april 1, 2007
Ulf Skyllberg (left) and Paul Bloom became fast friends after they began working together on mercury binding to reduced sulfur groups in organic material.
would be much more interesting. Bloom had a hunch that the binding of mercury to thiol ligands in organic matter would control the chemistry. He recalls saying at the time, “It’s gotta be reduced sulfur sites. Nobody is thinking that way; we gotta correct this!” After talking to Will Bleam of the University of Wisconsin, Madison, about some ideas, the group settled on synchrotron measurements. “There was not a lot of foresight in the beginning,” Bloom says. “Things just kind of fell together.” Their collaboration ultimately resulted in images of mercury interacting with NOM at the most fundamental structural level, showing that sulfur is © 2007 American Chemical Society
the key to binding, says Laura Sigg of Eawag (Switzerland). That information could help in determining how much mercury is available to microbes for methylation of the toxic metal. But the sleepless week in Brookhaven was not enough to confirm what the team was seeing. Skyllberg eventually traveled to Grenoble, France, to take advantage of a more powerful synchrotron, which allowed him to get more spectroscopic data. “I think we were very lucky,” he says. “The beam line has to be optimized; it varies from one day to another.” Meanwhile, several years passed and other work encroached, Skyllberg says. That time also gave Skyllberg the experience he needed to interpret the data, Bloom says. The additional measurements from Grenoble allowed Skyllberg “to explain some peaks we couldn’t explain” with only the Brookhaven data, he continues. “It made everything fall together, and we got some really good data.” “I think it’s very difficult to work with natural organic matter in general” because of its hetero
geneity, Sigg says. Applying EXAFS is “really quite new” and “technically difficult”, she adds. In addition to the expense and resources necessary for EXAFS, Sigg says, the “interpretation is also quite tricky. It requires quite a lot of insight to properly interpret these spectra. It seems this group has the expertise to do that.” Skyllberg says that this is the first time any researchers have been able to examine mercury complexation at environmentally relevant concentrations. Previous work at relatively high concentrations was published in ES&T by his group (Environ. Sci. Technol. 1999, 33, 257–261) and another (Environ. Sci. Technol. 2001, 35, 2741–2745). Skyllberg says that his group continues its research linking mercury geochemistry to ecological effects. But he will always remember that first week of measurements: “For some reason, you work hard, you are excited—everything is running around in your head,” he says. That state of mind contributed to his fruitful, sleepless nights that week, many years ago. —NAOMI LUBICK
“Compound Class Specific 14C Analysis of Polycyclic Aromatic Hydrocarbons Associated with PM10 and PM1.1 Aerosols from Residential Areas of Suburban Tokyo” by Hidetoshi Kumata, Eisuke Sakuma, Tatsuya Uchida, Kitao Fujiwara, and Mikio Tsuzuki, Tokyo University of Pharmacy and Life Science; Masao Uchida, Japan Agency for Marine-Earth Science and Technology (JAMSTEC); and Minoru Yoneda and Yasuyuki Shibata, National Institute for Environmental Studies (Japan), 2006, 40 (11), 3474–3480. Combustion-derived PAHs are important aerosol pollutants that have been linked to cancer in humans, but it is unclear exactly where these PAHs originate in cities, where their concentrations can be high. Are they mainly formed during fossil-fuel burning, or does biomass burning contribute as well? To answer those questions, Hidetoshi Kumata and colleagues turned to a technique for analyzing 14C that was originally developed for the analysis of marine sediments by Masao Uchida of JAMSTEC. Kumata and Uchida first had to adapt Uchida’s method to analyze atmospheric particles. 14C has a half-life of more than 5000 years, which makes it an ideal tracer for distinguishing between combustion products from fossil fuels (14C-free) and those from modern biomass (contemporary 14C). “In 2002, no paper on 14C analysis of atmospheric PAHs existed, so we thought we could be the very
Te tsuo Ak ashi
First runner-up: PAHs in Tokyo aerosols
Hidetoshi Kumata (second from left) and his students sample aerosols from a residential area in suburban Tokyo.
first to approach this question,” Kumata recalls. However, the work proved much more tedious and difficult than the researchers had expected. After 3 years, they finally got some results. The team collected aerosol samples at a site in suburban Tokyo with no direct source from industrial input. The goal was to learn more about how PAH sources vary depending on the season and particle size: fine particles of