NEWS
SOCIETY Mexico City aquifer depletion degrading water quality Mexico City faces a depleted potable-water aquifer that "is becoming increasingly vulnerable to contamination," according to a joint committee of the U.S. National Research Council (NRC) and the Mexican Academies of Science and Engineering, which released a preliminary report in March. The high level of economic development and industrialization and increasing urbanization have outpaced the government's ability to expand and repair water supplies and treat drinking water, sewage, and wastewater. According to Gary Krauss, study director for the committee, the aquifer system that supplies Mexico City is deep, but the water quality diminishes with depth. The aquifer lies within the Basin of Mexico. Mexico City covers about 3700 km 2 of the southern portion of the 9000 km 2 Basin. The city draws heavily on the Basin, which, although geologically distinct is linked hydrologically. Groundwater levels in the southern section are dropping at about 1 m per year. The decreasing aquifer level under Mexico City is resulting in unstable land. Some areas are sinking as much as 5 cm per year, Krauss said. The direction of
groundwater flow has changed because of the changing pressures caused by overpumping, he said. Overpumping also has resulted in the drying and cracking of the clay layer above the aquifer, making the aquifer more permeable and susceptible to contamination, Krauss said. At the same time, the lack of wastewater treatment is a growing concern. Urbanization and industrialization have increased faster than the city can build facilities to treat sewage and industrial effluents. The economy is not robust enough yet to make treatment facilities affordable. Direct exposure to untreated wastewater and potential contamination of the drinking water threaten public health. One option that has been explored is groundwater recharge, which thus far has been in limited use mostly for storm water runoff, Krauss said. "There are lots of different activities going on such as pilot projects and feasibility studies . . . but [Mexico City] does not have any largescale recharge project," he said. Injection also could be used to diminish the subsidence problem, he said. Efficient management of water resources is necessary if Mexico
Depletion of the Mexico City aquifer has caused the ground to subside an average of 5 cm per year. This well casing, about 100 years old and now closed, was originally just a few centimeters tall but now stands at more than 7 m.
City is to sustain the region's water while equitably providing for the needs of the citizenry, the joint committee said. The committee calls for price controls, public education, conservation, and water reuse programs. The committee also has recommended installing a water metering system for all but the poorest consumers, Krauss said. This would give the large industrial consumers incentive to conserve water. —DANI SHANNON
ACS approves undergraduate environmental chemistry program The University of Delaware's chemistry department has become the first to receive approval by the American Chemical Society for its undergraduate program in environmental chemistry. Though the program was just approved by ACS, two seniors graduated with environmental chemistry degrees this spring. John Burmeister, associate chair of the department, exulted in having the first approved program, though he said he was not surprised. Having been instrumental in establishing several other specialty chemistry tracks at Delaware, including a bio-
chemistry program, Burmeister said, "I feel kind of like a father in all this." The environmental chemistry course requirements include those necessary for a B.S. degree in chemistry plus a two-semester sequence in basic geology, biology, or geography. The geography courses include a semester of climate and life science and a semester of meteorology. Two semesters of advanced courses in ecology, civil engineering, climatology, atmospheric science, environmental geology, oceanography, or soil chemistry would be required, Burmeister said.
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Requiring nonchemistry courses that are currently offered enables students to obtain chemistry-based environmental expertise without the university immediately adding environmental chemistry faculty, Burmeister said. Last year, the ACS Committee on Professional Training established criteria for approving undergraduate environmental chemistry programs. According to Cathy Nelson of ACS's professional training division, a few other universities have submitted proposals that are under consideration. —DANI SHANNON
