Tracking America's exported air pollution - Environmental Science

Tracking America's exported air pollution. Paul D. Thacker. Environ. Sci. Technol. , 2004, 38 (18), pp 344A–345A. DOI: 10.1021/es040619r. Publicatio...
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says. And the midge has potential, but there’s still a long way to go. Midges have aquatic larval stages that are common in rivers and streams throughout the northern hemisphere. They tend to become relatively more abundant as streams become more contaminated, which indicates that either they are better able to detoxify certain pollutants, such as organic compounds, or they’re better able to

Scientists hope to use the midge flies commonly found hovering above rivers and streams in the northern hemisphere as sentinels of contamination for biomonitoring.

limit their exposure, says Charles Brandt, an ecologist at PNNL, which is part of the U.S. Department of Energy (DOE). With the help of a microarray system, he and his colleagues hope to use midges as sentinels to find out what contaminants are in a particular water body, assess exposure levels, and determine how the pollutants affect the insects. In this way, researchers

could detect pollutants before they became a problem. The one hitch, however, is that there is not yet a midge genome map. So the researchers have been substituting that of a distant relative—namely the thoroughly mapped fruit fly Drosophila—to do the exploratory work of finding environmental biomarkers, with the goal of eventually producing a midge-specific array. In controlled laboratory experiments, the PNNL researchers exposed the midges to various chemicals, extracted their messenger RNA, and tagged it with a fluorescent molecule. After flooding the Drosophila array with this RNA mixture, they obtained gene expression patterns specific to certain toxicants, in particular for the endocrine disruptor ethynylestradiol and the radionuclide strontium 90, a contaminant of great interest to the PNNL researchers because of their location near the DOE’s Hanford site on the Columbia River. Ultimately, they hope to catalogue gene expression patterns that match all major classes of pollutants, including heavy metals, polycyclic aromatic hydrocarbons, and pesticides. “We’ve had good success at discovering reliable up-regulated and down-regulated genes and identifying dose–response relationships for those genes,” Brandt notes. Because of microarray variabili-

Tracking America’s exported air pollution A consortium of 100 scientists from 6 countries has just completed a 6-week study of air pollution as it leaves the east coast of the United States, flows across the Atlantic Ocean, and hunkers down over Europe. Knowing the quantity of air pollution that America exports towards the east will help European Union officials set reasonable emissions goals for member nations and understand the health effects of this unwanted import. Alistair Lewis, a professor of chemistry at the University of York (U.K.), says that the heat wave in the

summer of 2003 made the deadly effects of air pollution all too clear. Elevated levels of ozone and PM10s are thought to have led to more than 800 deaths in London. While most of the air pollution was produced locally, little is know about how much was imported from abroad. “If you have ozone, it’s difficult to determine where it’s coming from: Some is local, some is regional, some is background,” says Lewis. Lewis and 40 other British researchers have positioned themselves in the Azores, a group of islands halfway between North


ty, the researchers want to further refine their experiments by normalizing the fluorescent signals, according to Jack Small, a PNNL scientist. Another open question involves studies to determine how gene expression changes over time and what concentrations organisms need to be exposed to before damage occurs. But the biggest part of the project is figuring out just how to use the data procured from the chips; this is still “very much a work in progress,” Small admits. The same holds true for related microarray experiments with rainbow trout, says Irv Schultz, an aquatic toxicologist with PNNL. Although the fish should also provide pollutant biomarkers and are of commercial interest, they’re not as promising a sentinel as midges because they are less common and aren’t as confined to a single area. “You may list the up- and down-regulated genes, showing how they altered in expression,” Schultz notes. In a more complex analysis, however, “you would look for sequence patterns that appear to be co-regulated in response to a chemical treatment. If you can identify enough sequences within a pattern, then it becomes a very distinctive signature for a particular toxicant that you might be able to recognize later when you work with an environmental sample, which is going to be much more complex.” —KRIS CHRISTEN

America and Europe. The Americans began tracking air masses as they left the northeast coast of the United States and then passed off the study to the British. The British then tracked the air to the coast of France, where French and German researchers followed the pollution as it traveled across Europe. Jim Meagher, air program manager for the National Oceanographic and Atmospheric Administration (NOAA), says that following a specific air mass is obviously quite difficult. But researchers hope that integrating computer weather models along with real time sampling from airplanes will yield high-quality results.


News Briefs Superfund site risks

The modified DC-8 airplane that NASA used to sample transatlantic air pollution carries dozens of onboard instruments that allow scientists to instantly analyze air samples for a broad range of different pollutants.

“It’s almost like a kinetic experiment in the lab where you’re watching the chemicals evolve over time: The gas converted to particles, and the nitrogen oxides and VOCs to ozone,” he says. During the study, research planes monitored this evolutionary process. Meagher says they will be able to track the same air mass by zeroing in on pollution signatures. For instance, one air mass was tracked because it contained acetonitrile. “This air mass was contaminated by fires in Alaska and Canada,” says Meagher. “Acetonitrile is a marker for biomass burnings.” Another air mass was found to contain sulfate aerosols. The planes performed real-time sampling every second for dozens of parameters, including ozone,

nitrogen oxides, and carbon oxides. Canisters of air were also collected for later measurements of hydrocarbons. Lewis says the hardest part of the project was calibrating all the equipment out in the middle of the Atlantic. “It’s tough because you have to get the two planes to meet in the air and then fly together for around an hour in the same air mass while checking all the instruments,” he says. Data gathering ended in August, and the teams plan to meet to discuss results sometime in January. The study will resume in the summer of 2006 when many of the same scientists will track air pollution from Asia as it treks across the Pacific to North America. —PAUL D. THACKER

Evaluating the safety of a nanofuture Nanoscience and nanotechnologies hold great promise, but much more risk assessment and research into health and environmental ramifications are needed, according to the United Kingdom’s Royal Academy of Engineering and the Royal Society. In a much-anticipated final report, experts ultimately saw “no case for the moratorium which some have advocated on the laboratory or commercial production of manufactured nanomaterials.” The group also believes that the current

European Union and U.K. regulations are “sufficiently broad and flexible to handle nanotechnologies at their current stage of development.” However, the report recommends taking certain precautions, such as limiting exposure and regarding free nanoparticles as hazardous materials, until more is known about their risk. Nanoscience and Nanotechnologies: Opportunities and Uncertainties, the final report released at the end of July, is at

The U.S. government is failing to protect people from exposure to health-threatening chemicals at 111 of the nation’s more than 1200 Superfund sites, charges a report released by the Sierra Club, a nonprofit advocacy group. The Bush Administration is the first in the program’s history to oppose the polluter-pays principle established for picking up the cleanup costs, thus forcing ordinary taxpayers to bear the full burden of remediating abandoned corporate sites, says the group. Since the late 1990s, the rate of completed cleanups has dropped by 50%, according to the report. It says that the U.S. EPA has insufficient data to determine whether human exposure is under control at another 158 Superfund sites, and it documents that migration of polluted groundwater is not under control at 251 Superfund sites. To access Communities at Risk, which was released in July, go to fund/report04/report.pdf.

Progress on pollution The number of cases of serious environmental pollution caused by industry in England and Wales dropped 12% to 613 in 2003, according to a United Kingdom Environment Agency report. The farming and waste management sectors made notable progress, cutting the number of cases by 27% and by 25%, respectively. But the July report says pollution incidents in the water industry rose by 25% and utility companies were the most frequent repeat offenders. The agency’s chief executive said fines for environmental offenses are still far too low to present any serious consequences to polluters. Spotlight on Business: Environmental Performance in 2003 is found at www. business/444255/833726.