aggerated. Radiation-induced carcinogenesis theory assumes a linear, no-threshold extrapolation from high dose to low dose. If the theory is correct, then a strong positive correlation should exist between radon exposure and lung cancer, even at low doses. Using radon measurement data from about 1600 U.S. counties and cancer mortality rates, Cohen found the opposite. For radon concentrations up to 3 pCi/L, lung cancer mortality rates decreased with increasing radon concentration. These results suggest thcit the cur~ rent theory of radiation-induced cinoeenesis is too conservative (Risk Afi&l 1996 15(6) 645-53)
SEDIMENTS Nitrogen concentration B. E. Frazier and colleagues measured ammonia nitrogen concentrations in sediment pore water at various depths and times throughout the year in the upper Mississippi river. Ammonia nitrogen concentration increased with depth and varied seasonally; the greatest concentrations occurred in summer. Total ammonia nitrogen concentrations correlated positively with the silt and volatile solids content of die sediments but not with clay. The authors concluded that seasonal and depth variations of samples should be taken into account when conducting sediment toxicity studies ,Environ Toxicol Chem 1996 15(2) 92—991
SOILS Degradation rates Microbial degradation rates for organic compounds in soils generally are derived from surface soils at ambient temperatures, but these often are not the operating conditions in the field. R. H. Veeh and colleagues modeled degradation rates of 2,4-D at different soil temperatures and depths to determine the effective degradation rate in field soils. Microbial populations decreased with depth and correlated positively with degradation of 2 4-D. Degradation decreased with temperature indicating that degradation rates vary with climate The results suggested that degradation rates should be modified in models to account for depth
and temperature variations and more closely mimic degradation of organic compounds in field soils. (J. Environ. Qual. 1996, 25, 5-12)
SURFACE WATER Mine drainage Known to oxidize organic pollutants, the hydroxyl radical is formed in illuminated surface waters most commonly through nitrate photolysis. However, surface waters affected by acid mine drainage generally have conditions under which the photolysis of ferric ions is more important in forming hydroxyl radicals. J. M. Allen and colleagues studied the formation rate and steady-state concentrations of the hydroxyl radical in surface water samples receiving acid mine drainage They found formation rates two to three orders of magnitude greater than those reported in normal siirfarp w?iters attributing this to the photolysis of iron and Fenton-tvoe reactions The results inrlicatpH that organic polluta n t s c o u l d b e nYidi7pH p f f p r t i v e l y in
surface \Amters rpr*pi\Hncr a c i d
mine drainapp (Fnvirnn Toxicol Contributors to Research Watch are 199K I5{2\ 107-13) Brian Eitzer, Connecticut Agricultural Experiment Station, New Haven, CT; Stephen Geiger, Remediation Technologies, Inc., King of Prussia, PA; Vincent Hand, Miami University, Institute of Environmental Sciences, Oxford, OH; Richard Hurst, CHEMPET Research Corp., Moorpark, CA; Louis Kovach, Ecolife Associates, Wiimington, DE; Raewyn Town, the Queen's University of Belfast, Northern Ireland; and Margaret Whittaker, NSF Internationa, Ann Arbor MI.
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1996 Brand new edition of the musthave reference! The tenth edition of this comprehensive directory contains the most current information on more than 16,000 faculty members in chemistry, biochemistry, biotechnology, chemical engineering, chemical technology, medicinal chemistry, and related fields at universities, four-year, three-year, and two-year colleges in the United States and Canada. Information for each of the 1,800 departments listed includes the degrees offered and the name academic rank, highest degree earned, electronic-mail address, and major teaching field(s) of each faculty member. New to this edition is the inclusion of department fax number, electronic mail address, gopher address, and World Wide Web page address. 208 pages (1996) Paperbound ISBN 0-8412-3300-4 $94.95 (plus $3.00 handling)
Correction In the February Research Watch, p. 64A, an item titled "In situ concentrators" should have stated that the researchers concluded that the semipermeable membrane device was an excellent screening tool, whereas the approved method, negative chemical ionization mass spectrometry, was limited as a screening tool (Environ. Toxicol. Chem. 1995, 74(11), 1875-84).
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VOL. 30, NO. 5, 1996 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 1 8 7 A
