Research Watch: Mercury presence

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tainty in Risk Assessments," /. Envi­ ron. Eng. 1999,125 (7), 660-666) TMDL calculations. A decision sup­ port system was developed to calcu­ late total maximum daily loads of various pollutants for water qualitylimited sections within a river basin. (Chen, C. W.; Hen, J.; Ziemelis, L.; Goldstein, R. A; Olmsted, L. "Deci­ sion Support System for Total Maxi­ mum Daily Load," /. Environ. Eng. 1999, 125 (7), 653-659)

MODELING Climate change. An atmospheric gen­ eral circulation model reveals greater cooling than the CLIMAP project in the equatorial current systems of the eastern Pacific and tropical Adantic Oceans. (Hostetier, S. W; Mix, A. C. "Reassessment of Ice-Age Cooling of the Tropical Ocean and Atmosphere," Nature 1999,399 (6737), 673-677) α-Hexachlorocyclohexane. In both model results and observations, the dramatic decrease in global emis­ sions of oc-hexachlorocyclohexane is reflected in rapidly decreasing con­ centrations in the atmosphere and seawater, except in the Arctic Ocean. (Wania, E; Mackay O.; Li, Y.-E; Bidleman, T. E; Strand, A. "Global Chemi­ cal Fate of a-Hexachlorocyclohex­ ane. 1. Evaluation of a Global Distribution Model," Environ. Toxi­ col. Chem. 1999,18 (7), 1390-1399) α-Hexachlorocyclohexane. Modeling results provide a comprehensive glo­ bal historical picture of the global be­ havior of a-hexachlorocyclohexane, which, after being used in huge amounts in the early 1980s, has since been essentially eliminated. (Wania, E; Mackay, D. "Global Chemical Fate of a-Hexachlorocyclohexane. 2. Use of a Global Distribution Model for Mass Balancing, Source Apportionment, and Trend Prediction," Environ. Toxi­ col. Chem. 1999 18 (7)) 1400-1407)

SOILS Mercury presence. It is proposed that erosion of deforested soils following human colonization constitutes a ma­ jor disturbance of the natural mercurv

Heavy metal accumulation Little is known about interactions of metals with individual benthic mi­ crobes in nature because of the technical difficulty of studying such small-scale processes in complex, heterogeneous sedimentary eco­ systems. T. Jackson and coworkers used energy-dispersive X-ray micro­ analysis (EDXM) and transmission electron microscopy (TEM) to inves­ tigate the accumulation of Cu and other elements by the cell walls, cytoplasm, cytoplasmic inclusions, fibrils and mineral coatings of indi­ vidual bacterial cells in the sedi­ ments of a lake polluted with heavy metals This represents the first aDDlication of modern EDXM and TEM techniques to the systematic quantitative analysis of statistically meaningful numbers of individual bap4.prj„l cpils \A/ith separate analv ses of snpcific cell components and assn riatpri nnnlii/ing

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cycle and may explain the increase of mercury burdens in Amazonian aquatic ecosystems in newly colo­ nized watersheds. (Roulet, M., et al. "Effects of Recent Human Coloniza­ tion on the Presence of Mercury in Amazonian Ecosystems," Water, Air, SoilPollut. 1999,112 (3-4), 297-313)

WASTEWATER Disinfection-resistant bacteria. It is suggested that the oxidation towers of a wastewater treatment plant in Wil­ liamsburg, Va., supported growth or recovery of fecal coliform bacteria and that this bacterial subpopulation seem­ ed to increase resistance to routine chlorine disinfection. (Scully, E E., Jr., et al. "Development of DisinfectionResistant Bacteria During Wastewater Treatment," Water Environ. Ress.999, 71 (3)) 277-281) Reuse practices. The status of wastewater reclamation and reuse around the Mediterranean basin is presented with a discussion of exist­

ing guidelines and regulations, as well as the possibility of developing uniform wastewater reuse standards. (Angelakis, A. N.; Marecos Do Monte, M.H.E; Bontoux, L.; Asano, T. "The Status of Wastewater Reuse Practice in the Mediterranean Basin: Need for Guidelines," Water Res. 1999,33 (10), 2201-2217)

WATER Contaminated fish. In a survey con­ ducted among anglers in New Jersey's Newark Bay Complex, it was found that although 60% of the anglers had heard about fish consumption adviso­ ries, they either did not believe them or were unconcerned about health effects from eating contaminated spe­ cies. (Pflugh, K. K.; Lurig, L.; Von Hagen L. A; Von Hagen; Burger, J. "Ur­ ban Anglers' Perception of Risk From Contaminated Fish" Sci. Total Envii 1999 228 (2-3), 203-218) Humic substances. Results from a variety of spectroscopic techniques suggest the incorporation of light carbon sources in the humification process, rather than 13C enrichment due to trophic effects. (Schulten, H.-R.; Gleixner, G. "Analytical Pyrolysis of Humic Substances and Dis­ solved Organic Matter in Aquatic Systems: Structure and Origin," Wa­ ter Res. 1999, 33 (11), 2489-2498) Membrane filtration. Transport mea­ surements of natural organic matter (NOM) rejection and flux are de­ scribed consistently using a resistances-in-series model that considers membrane characteristics and NOM properties. (Cho, J.; Amy, G; Pellegrino, J. "Membrane Filtration of Nat­ ural Organic Matter: Initial Compari­ son of Rejection and Flux Decline Characteristics With Ultrafiltration and Nanofiltration Membranes" Water Res. 1999 33 (11) 2517-2526) Pesticide contamination. In a study in which the ecological risks of mod­ ern pesticides related to different Eu­ ropean river/estuary systems are com­ pared, it is found that pesticides exert a significant pressure on the aquatic system. (Steen, R.J.CA., et al. "Ecologi­ cal Risk Assessment of Agrochemicals in European Estuaries," Environ. Toxi­ col. Chem. 1999,18 (7), 1574-1581)

NOVEMBER 1, 1999 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS » 4 7 1 A