Environmental t News High levels of particulate pollution in Chinese megacities MINGTUO CHEN
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he most comprehensive study yet of organic pollutants in Chinese urban air is published in this issue of ES&T (pp 4619–4625). Conducted by a team of researchers from China and Japan, the study is the first to compare levels of organic aerosol particles in China’s newly developing midwestern cities with levels in older megacities such as Beijing, Hong Kong, and Shanghai. The research confirms that most of the 14 cities studied have much higher levels of air pollution than cities in developed countries. Particulate matter (PM) is made up of a complex mix of inorganic and organic compounds, dust, and soil. Fine particles 31 million, an increase of 30% from 2004. The study collected the first nationwide data on phthalates in Chinese aerosols, Wang says. Although very high levels of phthalates were found in all of the studied cities in both seasons, the levels were highest during the summer. The higher summertime concentrations can probably be explained by the elevated ambient temperatures, which facilitate evaporation, he says. PM aerosols are also associated with environmental problems both within and beyond China: “High levels of carbonaceous aerosols have been linked to the increase
The researchers expected to find high soil levels of DDT in this field because large amounts had been applied before 1972 and the soil’s high organic content is a magnet for fat-loving DDT, says Perihan KurtKarakus, an environmental scientist at Lancaster University (U.K.) and lead author of the study. However, the scientists were stunned when they estimated that by evaporation alone it would take 200 years for half the DDT in the soil to dissipate, Bidleman says. Fortunately, other mechanisms, such as breakdown by microbes, bring the actual dissipation rates of DDT in soil down to the order of decades, not centuries, he says. In contrast, two surveys of southern U.S. agricultural soils that were done within the past 10 years found that only 1 out of 100 sampled soils exceeded 0.7 mg/kg. Southern U.S. farm soils, which are low in organic matter, are calculated to have a DDT half-life of 5–20 years, Bidleman says. “The concentration of DDT in soil can vary 1000-fold depending on the past application rate, organic matter content, and cultivation practices,” he says. The researchers would like to repeat the study on other soil types, then combine the data with GIS (geographic information system) maps of land use to predict soil residues and evaporation of
PERIHAN KURT-K AR AKUS
Environmentalt News
Measurements of temperature gradients and the vertical component of wind speed in the top 2 m above this farm field helped to show that DDT will be evaporating off the soil for a long time.
DDT over large geographic areas. The Organisation for Economic Co-operation and Development is currently adopting models to assess the long-range transport potential of chemicals, Blais says. “We can draw from our DDT experience to learn and ultimately place this information in the models and use DDT to [verify the accuracy of] the models,” he adds. “This study and others like it indicate that we will be exposed to a sea of chemicals in the atmosphere
Drop in EU carbon prices baffles analysts April and May were a roller-coaster ride for the EU’s flagship CO2 emissions trading scheme. Carbon prices dropped by more than half in the first week of May, from €32/tCO2 to 99% of allowances allocated. The shortfall was ~25% in Estonia, with other countries reporting
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for quite a while to come,” says Mary Jane Incorvia Mattina, an analytical chemist with the Connecticut Agricultural Experiment Station. In most cases, environmental exposures to individual contaminants involve relatively small concentrations, but the sum total of exposure to banned pesticides, such as DDT, chlordane, and toxaphene, on top of the smorgasbord of new chemicals on the market, may be impinging on our overall health, she says. —JANET PELLEY
8–15% fewer emissions than anticipated. In France, this amounted to ~19 million t of surplus allocations. The trading scheme, which covers electricity producers and energy-intensive manufacturers, relies on polluting companies to buy and sell CO2 emission allowances, which are handed out by the government. One allowance allows the owner to emit 1 t of CO2. Companies that limit their emissions to below their allocation can sell surplus allowances to companies that emit more than they are allowed. Several possible reasons exist for the recent surge in surplus allowances. One explanation, fa-
nies have less incentive to cut their emissions to free up credits that can be sold. Tangen has already observed a halt in investments in environmental projects in developing countries. Because companies can easily buy emissions credits at home on the market, they don’t look for ways to generate extra credits by investing in reduction schemes in other countries. Before carbon prices dropped, he says, the scheme had a large impact in developing countries. All eyes are now focusing on the scheme’s second trading period, which covers 2008–2012, when the EU must meet its targets under Kyoto. The deadline for member states to submit new emissions allocation plans to the EC for this phase was June 30. These plans, which must be approved by the EC, help set the total permitted level of CO2 emissions from facilities. EU Environment Commissioner Stavros Dimas has said that he will be tough but fair when judging the new plans, in an effort to make sure that over-allocation won’t happen again. Despite market uncertainty, Tangen predicts that few companies will drop out of the trading program. “It has gained momentum,” he says, “and companies now have established trading units. This dynamic will continue, but with prices so low, companies will be focusing more on the long term.” —MARIA BURKE
Tires and lead: A weighty issue Tires crunch against street curbs or come to a screeching halt when drivers stop or swerve suddenly. In the process, one or more of the weights clipped to the wheels to balance the tires—2.5 oz/car wheel on average—may get thrown off onto the roadway. In 2003 alone, ~2000 t of lead may have been lost from vehicles in this fashion, according to estimates released in May by the U.S. Geological Survey (USGS).
The USGS study tracks the flow of lead-based wheel weights from their manufacture, through their use, recycling, and disposal. In 2003, ~28,000 t of lead were used in the production of wheel weights in the U.S., and ~65,000 t were attached to the 232 million registered cars, light trucks, and commercial vehicles traversing U.S. roadways, the analysis shows. Given those figures, the 3% lost
News Briefs Pyrethroids pollute urban runoff
Commonly used pesticides have been found at toxic levels in the sediments of urban streams. The results were released in April by the Urban Pesticide Pollution Prevention Project, a public–private partnership studying the San Francisco Bay Estuary. Now that household use of organophosphate pesticides has been phased out, pyrethroids have come to dominate the market in residential pesticides. They are the most common active ingredient in bug sprays. Multiple pyrethroids were detected, but bifenthrin contributed the most to the toxicity. The levels that cause acute toxicity to tiny shrimp-like animals called amphipods are only slightly above current analytical detection limits. Go to http://www.up3project.org/up3_ index.shtml for more information.
Nanosponges go commercial
Nanosponges will soon be sopping up pollutants from coal-fired power plants and other industries, according to the U.S. Department of Energy’s Pacific Northwest National Laboratory, which developed the technology. Also known as self-assembled monolayers on mesoporous supports (SAMMS), the nanosponges capture and immobilize contaminants like mercury from a wide variety of industrial wastes. Because these contaminant-loaded SAMMS can be disposed of like ordinary waste, the developers claim that their potential to reduce industrial costs is “huge”. The initial market will be coal-fired power plants, but companies intend to develop technologies to remove mercury from fly-ash byproducts, such as concrete or gypsum. One company predicts that SAMMS could benefit mining, pulp and paper processing, municipal waste operations, and chemical plants.
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vored by analyst Kristian Tangen of Point Carbon in Oslo, is that the allocations were based on poor historical emissions data. Another possible, though less likely, reason, says Tangen, is that companies reduced emissions more than expected. Whatever the explanation, the market calmed down after a week, with carbon prices stabilizing at €15–18/t-CO2. “But the market remains very volatile,” adds Tangen. “Very few people understand what’s happening at the moment.” The EU’s flagship climate policy is now in danger of stalling, warns Matthias Duwe, the director of Climate Action Network Europe, an environmental group. He accuses European governments of responding to pressure from industries and blatantly ignoring the aims of the trading scheme. “Figures show that . . . generous emission allowances granted to companies are causing the decline in carbon prices and distorting the market. This also reduces the credibility of the emissions trading scheme.” Stephan Singer, the director of the European Climate and Energy Policy Unit of WWF, an environmental group, adds that this could undermine the credibility of the EU in the negotiations for new Kyoto Protocol targets after 2012. One thing is clear: Low carbon prices are bad news for the EU’s efforts to reduce greenhouse gas emissions. As prices fall, compa-
Environmentalt News The USGS study is important because “it’s the first [official] attempt to try and get a grasp on what the inventory is and what the scope of the potential problem is,” says Jeff Gearhart, campaign director for the ECOLOGY CENTER
along roadways may not seem like much, especially when spread out across the entire continental U.S. But much of it is probably concentrated in urban environments, where most of the stop-and-go traffic occurs, notes Donald Bleiwas, a USGS minerals and materials specialist and author of the report. Additionally, lead wheel weights have been used on vehicles for nearly 70 years, so the cumulative amount of lead dispersed in the environment in this way could be significant. How big an environmental problem that poses depends on what happens to the weights after they fall off. Do they get ground up by traffic? Do the abraded particles become airborne? Does storm water wash them off roads? Do they make their way into nearby soils, or get transported into urban ponds and groundwater? Do they get picked up by street sweepers? Do hobbyists pick them up and mold them into other items, such as lead weights used by anglers? “I can’t answer that side of the equation,” Bleiwas admits, but wheel weights “could contribute to the presence of residual lead content in some soils in urban environments.” Historically, the main source of lead in U.S. soils was emissions from leaded gas, and they have decreased substantially since it was phased out beginning in 1973.
The USGS estimates that in 2003 alone, 2000 t of lead may have been dispersed into the environment from automotive lead wheel weights.
Ecology Center, an environmental organization. His group sponsors a project looking at toxic materials in vehicles. “Wheel weights are the second largest use of lead in vehicles after lead–acid batteries, and they’re the one use that continues to be dispersed into the environment more than any of the other uses,” Gearhart points out. The EU began banning the use of lead wheel weights last year on new vehicles and replacement tires because of environmental concerns about losses along road-
More than just perchlorate? The presence of perchlorate in foods has attracted widespread attention because of the chemical’s ability to interfere with iodide uptake by the thyroid. But other chemicals found in food can also inhibit the uptake of iodide, an essential component of the thyroid hormones that direct brain development. Researchers are now looking beyond perchlorate at other iodide blockers, including thiocyanate and nitrate, to determine
whether they are cause for concern. “The question of the impact of multiple sources of perchlorate and multiple iodine blockers is not known,” says Gregory Brent, a medical professor at the University of California, Los Angeles. Chief among these other iodide blockers are thiocyanate and nitrate, says John Gibbs, medical director at former perchlorate manufacturer Kerr-McGee. To get a better handle on overall iodide availability, Benjamin
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ways and inappropriate disposal by tire retailers and scrap processors. No federal regulatory controls currently govern the use of lead wheel weights in the U.S., but car manufacturers, including most U.S. companies, are slowly moving toward other materials, Gearhart notes. Zinc and steel are the most common alternatives. However, the vast majority of wheel weights (~80%) go into replacement tires, Gearhart says. Ironically, even though you might buy a new car with lead-free weights, lead will go back in once you put new tires on. The U.S. EPA encourages tire dealers to begin using lead-free weights under a voluntary initiative, but the agency rejected a petition by the Ecology Center last year to ban the use of lead weights, saying more research is required. Nevertheless, a growing number of states, cities, and private fleets are moving in that direction because of environmental concerns. In 2004, Minnesota became the first state to begin replacing lead weights on its state fleet with leadfree alternatives. “Our approach to this whole thing is pollution prevention,” says John Gilkeson, a principal planner for the Minnesota Pollution Control Agency. “We know lead’s a problem; we know it comes off wheels. If we’ve got an alternative, let’s do it.” —KRIS CHRISTEN
Blount and colleagues at the U.S. Centers for Disease Control and Prevention recently published a new method for quantifying iodide and its blockers, perchlorate, thiocyanate, and nitrate, in human amniotic fluid. “We know that you need perchlorate and iodide exposure data to get a good picture of iodide to the thyroid—that’s critical,” says Blount. “These other chemicals may also affect the picture,” he adds. In developed countries, the main source of exposure to thiocyanate is cyanide in tobacco smoke, which is
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Nitrate levels in leafy vegetables are many thousands of times higher than perchlorate levels. The two chemicals may have an additive effect in inhibiting the uptake of iodide by the thyroid.
ter. Using Gibbs’s potency factors to convert nitrate to perchlorate equivalents, Sanchez and colleagues found that, in most green leafy vegetables, nitrate has >100× the iodide-inhibiting effect of perchlorate. Sanchez has also measured thiocyanate in broccoli and found 15,000 g/kg. This would be equivalent to 30,000 g/kg perchlorate, if Gibbs’s potency factors are correct. Gibbs’s potency factors are a good first step, says Herschman, but they can’t really be applied to food. “To determine whether particular foods and chemicals in them alter human thyroid hormone production, the steps necessary are cell studies, animal studies, and then carefully controlled human studies,” he says. One of the few investigations of nitrate’s ability to block iodide uptake in humans, a 2000 study conducted at the Netherlands National Institute for Public Health and the Environment, suggests that nitrate is not likely to significantly inhibit iodide uptake. The scientists gave 10 healthy human volunteers 15 mg NaNO3/kg body weight for 28 d. At the end of the exposure period, no change had occurred in the iodide uptake of the volunteers, even though the volunteers were on an iodine-restricted diet. The researchers also found no effect on thyroid hormone levels in the volunteers’ blood. Regulators in California and Massachusetts, states that have established some standards for perchlorate, acknowledge that nitrate and other iodide inhibitors may play a role in determining the risk of perchlorate exposure. They qualitatively allow for this possibility in their uncertainty estimates and in their assumptions for the amount of perchlorate that comes from food as opposed to drinking water. To reduce that uncertainty, “We will need to have epidemiologic studies that integrate all forms of exposures with thyroid function to determine the cumulative effects,” says Brent. —REBECCA RENNER
News Briefs Clarke Prize
The National Water Research Institute (NWRI) will award its prestigious Athalie Richardson Irvine Clarke Prize to Philip C. Singer, an environmental engineering professor at the University of North Carolina (UNC) at Chapel Hill. In addition to his teaching and research, Singer, a former ES&T Associate Editor, currently serves as director of UNC’s Drinking Water Research Center, which he worked to establish in 1998. In awarding the Clarke Prize to Singer, NWRI noted his work on ozone chemistry, which laid the foundation for oxidation processes as a means to purify water. Singer has also studied disinfection byproducts, which are created when chlorine reacts with organic matter during water purification. The institute’s annual prize comes with $50,000, which will be bestowed at a ceremony this summer.
Bioenergy: Fuel of the future
A report from the European Environment Agency concludes that the EU can produce enough energy from waste and agriculture to support renewable energy goals without putting pressure on biodiversity or soil and water resources. The study projects that by 2010, the biomass from agriculture, forestry, and waste should equal 190 Mt of oil, enough to meet the EU’s renewable energy targets. The energy in biomass is measured in oil equivalent or Mtoe. By 2030, the EU expects to produce 295 Mtoe, which will supply 15% of its energy needs. This switch to biomass also would reduce CO2 emissions by 400–600 Mt. Waste will provide the most bioenergy in the short term, but biomass from agriculture will eventually dominate the market.
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metabolized in the body to thiocyanate, a relatively potent iodide uptake inhibitor. “Smoking has been shown to reduce the amount of iodide in breast milk because thiocyanate interferes with iodide uptake,” says University of California, Los Angeles, medical center endocrinologist Jerome Hershman. Cruciferous vegetables such as broccoli, cabbage, and Brussels sprouts are also a source of thiocyanate. Unless properly processed, cassava, eaten as a starch in tropical regions, can contain large amounts of cyanogens, which are metabolized in the body to thiocyanate. Nitrate is present in many common foods, often at much higher levels than perchlorate. In leafy vegetables, nitrate levels are ~10,000× greater than perchlorate levels. In 2004, Gibbs and colleagues published a paper on in vitro experiments to evaluate the relative potency of thiocyanate and nitrate. They exposed Chinese hamster ovary cells expressing the human protein that controls iodide uptake to individual inhibitors at various doses and to combinations of inhibitors. Perchlorate is 250× more potent than nitrate and 15× more effective than thiocyanate. “We confirmed previous work on the relative potency and showed that over a wide range of exposures the effect of the three is additive,” says Gibbs. Most leafy vegetables have relatively high nitrate values, says Charles Sanchez, a soil scientist at the University of Arizona’s Yuma Agricultural Research Cen-
Environmentalt News PERSPECTIVE
Swedish cottagers were greeted by a foot-thick scum of rotting algae on coastal island shores last summer as the Baltic Sea heaved up one of its worst cyanobacteria blooms ever. Sweden’s inability to rein in the algal blooms, despite a world-class nutrient-control program, has elicited criticism of the government’s tough policy of cutting both nitrogen and phosphorus. Now, a panel of five eminent North American scientists has released a report that supports Sweden’s stand on phosphorus, but they remain deadlocked over how to handle nitrogen. Eutrophication of Swedish Seas calls for aggressive reductions in phosphorus inputs to alleviate algal blooms and oxygen-starved “dead zones” in the Baltic Sea and inlets along Sweden’s east coast. The report, which was released on March 20, explains that algae thrive on both nitrogen and phosphorus. Moreover, when the ratio of nitrogen to phosphorus is below a unique threshold, growth is limited by nitrogen, but when the ratio is high, phosphorus controls the growth rate. The experts, who were called in by the Swedish EPA, agree that Baltic algae are being fed too much phosphorus, but they differ on whether nitrogen has a special role to play. The debate holds lessons for resource managers worldwide who are struggling with the growing problem of nutrient over-enrichment of brackish coastal waters, says Fred Wulff, a marine ecologist at Stockholm University. “The case for phosphorus reductions has been well demonstrated,” says Robert Hecky, an aquatic ecologist at the University of Waterloo (Canada) and a coauthor of the report. Sweden cut phosphorus inputs to the Stockholm archipelago by 90% from 1970 to 1980, slashing algal production by 50% by the mid-1980s, according to the report.
NASA
Do nitrogen cuts benefit the Baltic Sea?
Current phosphorus concentrations in the Baltic Sea are extremely high. If sunny, windless days prevail, toxic blue-green algal blooms, like this record-breaker seen from space on July 13, 2005, could recur this summer.
In 2004, Sweden contributed ~13% of the excess phosphorus dumped in the Baltic each year from sewage treatment plants and farm runoff, according to the Helsinki Commission, a coalition of 9 Baltic countries. Additionally, the 9 member countries of the Helsinki Commission have a nonbinding agreement to reduce phosphorus emissions by 50% from 1989 levels by 2005, but not all have reached the target, says Roger Sedin, director of the zero eutrophication program at the Swedish EPA. However, the main reason that Sweden’s phosphorus removal program hasn’t had much impact on the Baltic is because of inaction by other countries, especially former members of the Soviet Union. Scientists have seen no substantial reduction in overall phosphorus loading over the past 25 years, Hecky says. Great opportunity exists for improvement, beginning
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with removing phosphorus from detergents and from point sources, the report concludes. Sweden began to invest in nitrogen reduction from farms and sewage treatment plants in the mid-1990s as a response to mandatory goals set by the EU’s Water Framework Directive as well as research suggesting that nitrogen cuts could reduce algal blooms, Sedin says. In the waters of the Stockholm archipelago, nitrogen loads dropped by ~50% after 1998 compared with the 1980s, and algal production declined by ~15–40% in the summer, according to the report. Whereas the spring algal bloom is still limited by phosphorus, by summertime the algae are short of nitrogen and this is when the declines in production are seen, demonstrating the efficacy of nitrogen removal, says Ragnar
Elmgren, a marine ecologist at Stockholm University. “We’re seeing different things,” Hecky says. The nitrogen-removal technology extracted ammonia and organic matter, both of which remove oxygen from the water as they decompose, he explains. By reducing the biological oxygen demands associated with the excess ammonia and organic matter, the technology boosted oxygen concentrations in the bottom waters. Because phosphorus that has accumulated in the sediments over many years can be released to the water under low-oxygen conditions, the nitrogen removal technology—by elevating oxygen levels—may have also reduced phosphorus inputs from the sediment, thereby driving down algal production, Hecky says. Experiments show that algal growth in the waters of the Stockholm archipelago is limited by both nitrogen and phosphorus, similar to estuaries on the U.S. east coast, says Don Boesch, a biological oceanographer at the University of Maryland and a coauthor of the report. Because algal growth in the archipelago is limited by nitrogen in the summer, the nitrogen cuts are decreasing summertime algal production; this reduces organic matter inputs to the bottom and elevates oxygen levels, helping to keep phosphorus locked in sediments, he says. However, the effect of the nitrogen cuts on the open Baltic has been far less clear. The debate has focused on data showing that cyanobacteria, blue-green algae, “fix”, or absorb, 300,000–600,000 t of nitrogen from the air every year, a level that makes it the single largest source of the nutrient to the Baltic. The findings led critics in the Swedish EPA and the Swedish scientific community to charge that controlling nitrogen is fruitless because the cuts from sewage and farming will instead favor the growth of cyanobacteria. When phosphorus concentrations are high, algal growth is
limited by nitrogen, which gives cyanobacteria a competitive edge over other algae in midsummer because they can supply themselves with nitrogen from the air, Hecky explains. In the Baltic, algal production is still tuned to phosphorus, and if nitrogen is removed too fast, it could create favorable conditions for cyanobacteria, he cautions. These toxic blooms then defeat any cuts by Sweden or the EU by fixing nitrogen from the air, Sedin says. However, the springtime bloom is dominated by other algal species, such as diatoms, which thrive on the nitrogen-rich water that is brought up from the bottom of the Baltic in spring, Elmgren says. When the spring bloom dies and sinks, it ultimately robs the bottom water of oxygen, triggering release of phosphorus in the sediment that feeds the cyanobacteria bloom in midsummer, he says. “Both nitrogen and phosphorus should be controlled,” says Daniel Conley, a nutrient biogeochemist at the National Environmental Research Institute (Denmark). Studies show that hypoxia in the Baltic is responsible for releasing 50,000– 80,000 t of phosphorus from the sediment every year, far more than the 15,000 t from external sources, he says. Phosphorus release from sediments and the accompanying cyanobacteria blooms will continue until the low-oxygen zones are eliminated, and that will require cuts in both phosphorus and nitrogen, he says. This analysis appears to be borne out by a model developed by Wulff. It shows that if all the Baltic countries removed 95% of the phosphorus and 70% of the nitrogen from sewage treatment plants, then the oxygen-poor dead zone would decline by ~25%, and cyanobacteria blooms would dramatically decrease. The Swedish EPA is evaluating the report and is likely to put more emphasis on phosphorus removal while maintaining current nitrogen-reduction measures, Sedin says. —JANET PELLEY august 1, 2006 / Environmental Science & Technology n 4539
