Research M Watch Mercury pollution on the rise in Greenland
According to the researchers, long-range atmospheric transport does not account for this observed European scientists report a longgeography-dependent concentration term trend of increasing mercury levgradient. Other factors must be conels in lake sediments in Greenland. tributing, such as the influence of meteorological conditions near 50˚ Inland 53˚ Kangerlussuaq the margin of Greenland’s inland Ice 24 19 Lake 70 25 ice sheet on mercury enrichment 67˚ 5 6 4 in area lakes, but there is consid69 48 91 Sisimiut 66 erable uncertainty. An improved 89 46 58 63 Nunatak 40 rd Lake understanding of localized geo★ fjo 39 m 44 rø logical and climatological conSt re d Lake 53 n 66˚30´ ditions and effects is essential for Sø 51 describing how pollutants are se0 50 km Sukkertoppen questered in the Arctic, say the Ice Cap scientists (Environ. Sci. Technol. 2001, 35 (9), 1736–1741). Lake sedimentsnearGreenland’sinland ice sheetaccumulate more mercurythan lake sedimentsnearGreenland’scoast. Their research suggests that the rise may have begun as early as the 17th century and points to industrial and preindustrial contaminant sources. Lead author Richard Bindler at Umeå University in Sweden and a team of scientists from Sweden, Denmark, and the United Kingdom report that their data indicate a threefold enrichment of mercury over natural background levels in Arctic sediment samples. Pollution occurring since the mid-19th century is ascribed to long-distance, atmospheric transport of mercury to Greenland from industrial centers to the south, in Europe, and elsewhere. Mercury mining in southern Europe is suggested as a possible source of contamination occurring before 1800. The authors note that although such pollution of the Arctic by longrange transport of mercury is documented, severe knowledge gaps remain, and some observations cannot yet be fully explained. For example, in the present study, it was found that throughout an extended period of time, spanning centuries, much more mercury accumulated in sediments in a lake near the inland margin of Greenland’s ice sheet than in lakes nearer to Greenland’s coastal regions. 234 A
I
Ozone hole recovery linked to climate change Changes in greenhouse gas (GHG) concentrations during the first half of the 21st century will produce atmospheric effects that accelerate the removal of ozone-destroying chlorofluorocarbons (CFCs) in the stratosphere, say two British scientists. They predict that as a result of GHG buildup, recovery of stratospheric ozone to levels currently predicted to occur in 2050 and 2080, will instead occur in 2045 and 2070, respectively. The shortened timeframe for ozone hole recovery occurs, according to Neal Butchart and Adam Scaife of The Met Office in Berkshire, England, because increasing concentrations of GHGs in the troposphere facilitate rapid transport of ozone-depleting compounds such as CFCs from the troposphere to the lower stratosphere. There, CFCs are rapidly photolyzed, and the whole process of CFC removal is sped up. The researchers’ findings are based on the use of a global climate model and assumptions about the GHG concentrations for the time period studied. The predicted effects have not previously been quantified in other climate change analyses. Tests of the model’s
ENVIRONMENTAL SCIENCE & TECHNOLOGY / JUNE 1, 2001
sensitivity to possible variations in selected parameters did not substantially alter the outcome predicted to occur over the long time scales studied. The authors of the study also note that their findings have ramifications for GHGs in general, as the same processes that transport CFCs to the stratosphere also act on other GHGs, which could then similarly be decomposed if they are susceptible to photolytic attack in the stratosphere (Nature 2001, 410, 799–802).
Grabbing CO2 out of the air Researchers at Los Alamos National Laboratory and the University of California–Irvine suggest that a good way to limit the buildup of CO2 in the atmosphere is to pull it out of the air with engineered scrubber ponds. Scrubber ponds capitalize on a simple reaction. At room temperature, aqueous calcium hydroxide reacts with CO2 to form solid calcium carbonate, or limestone. Heating the calcium carbonate produces CO2 gas and calcium oxide (CaO). Solid CaO is then recycled back into the scrubber pond, and the CO2 gets pressurized and reacted with magnesium-rich rock to create magnesium carbonate rock. To scrub the atmosphere, Hans Ziock, Scott Elliott, Klaus Lackner, and colleagues rely on the wind to sweep air over the ponds. Atmospheric mixing processes should ensure that CO2 reductions affect the entire lower atmosphere, says Ziock. The scientists estimate that an enormous scrubber with an area several hundred thousand square kilometers would remove nearly all of the anthropogenic CO2 produced annually in the world—about 7 gigatonnes. Increasing the active surface area by building scrubber walls or fences would reduce the amount of land that would need to be devoted to the project. The researchers’ scrubber pond proposal is aimed at capturing CO2 emissions from the transportation
Recycling plant risks As the number of recycling plants grows worldwide, so do concerns about health and safety risks at these facilities. A recent analysis of three recycling plants in Canada confirms that workers there are exposed to unacceptable health and safety risks. The study, which was performed by two Canadian researchers, reveals that concentrations of bacteria, molds, and chemical contaminants exceed workplace standards. They also note excessive job-related injuries and illnesses compared with the average for the service sector. Biologist Jacques Lavoie of the Québec Occupational Health and Safety Research Institute and Serge Guertin, an industrial engineer with Québec-based Ergo-Norme, Inc., suggest that plant designers and managers need to understand these issues, so that when trying to solve one problem, more are not created. Recycled materials are a valuable resource, but their recovery should not be accomplished at the expense of creating worker health and safety problems. The scientists largely attribute the elevated concentrations of microorganisms to the storage and handling of recyclable materials and find less of a problem in receiving and shipping operations. Problems with microorganism exposures occurred primarily in the summer months. Carbon monoxide, which is associated with forklift operation, is the principal chemical contaminant of concern. Noise pollution was also confirmed by the study. Ergonomic risks were mainly associated with worker movements, posture, and the effort required to sort materials (J. Air Waste Manage. Assoc. 2001, 51, 352–360).
Phthalates abundant in the house Phthalates appear to occur in house dust and indoor air at levels that are an order of magnitude higher than other contaminants such as polycyclic aromatic hydrocarbons (PAHs), according to researchers who are investigating possible environmental triggers for breast cancer and other diseases. The finding is Researcherprebased on a pilot paresto collect study that was conindoordustsamducted by environplesbyinserting a collection thim- mental toxicologist ble into the exten- Ruthann Rudel at Silent Spring Instision piece ofa vacuum cleaner. tute in Newton, MA, and colleagues at the Southwest Research Institute in San Antonio, and Harvard University School of Public Health in Boston. The scientists analyzed indoor air and dust for 86 chemicals, including phthalates, pesticides, alkylphenols, bisphenols, PAHs, and polychlorinated biphenols (PCBs). These chemicals have a potential role in breast cancer etiology because they either cause mammary tumors in animals or disrupt the human endocrine system. The researchers analyzed six dust samples from different locations in three houses and one office. Seven air samples from homes, workplaces, and an 11-hour shopping trip that included stops at a hardware, garden supply, office supply, toy, and department store, were collected using a personal sampling pump. Phthalates were found at the highest levels in dust (0.3–524 µg/g) and air (0.005–2.8 µg/g) samples. Although adults are not significantly exposed to dust, it may provide a useful record of past indoor chemical use and exposure, the authors state. For children, dust is a potentially important exposure pathway. The scientists found 33 out of the 86 tested compounds in house dust and 24 out of 57 in air. In addition to phthalates, they found detectable levels of 12 pesticides in dust and 7 in air samples. Nonylphenol and its breakdown products were prevalent in dust (0.82–14 µg/g), as were estrogenic phenols such as bisphenol A. The analytical methods developed for this pilot study are currently being TANYA SWANN
sector, says Ziock. Transportation accounts for just over one-third of annual worldwide CO2 emissions; however, with millions of small sources, a method to collect the gas is difficult to devise, says Ziock. The cost of grabbing CO2 using scrubber ponds would not be very high compared with the price of gasoline. It would cost about 20¢ per gallon to extract CO2 and convert it to a gas stream and slightly less to create the magnesium carbonate rock (Geophys. Res. Lett. 2001, 28, 1235–1238).
used in a study that will examine ~120 homes for the relationship between indoor air and dust measurements and urinary biomarkers (J. Air Waste Manage. Assoc. 2001, 52, 499–513).
Platinum group metals in airborne particulates A study performed by German researchers reveals that although concentrations of platinum and rhodium in airborne particulate matter have increased over the past decade, current amounts remain far below levels expected to cause observable health effects in humans. The analysis also indicates that fine particulate matter (
