and sediments spiked with copper sulfate. Sediments spiked with methyl parathion were unaffected. Results show that using this bioassay for toxicity testing on the solid phase of sediments of differing particle size distributions requires extreme cau tion. [Environ. Toxicol. Chem. 1995, 24(3), 411-14)
Dioxins and furans Current methods for analyzing diox ins and furans in effluents require both the Soxhlet extraction for fil tered particulates and liquid-liquid extraction for filtrate with both ex tracts. Κ. Ζ. Taylor and colleagues tested a method using solid-phase extraction (SPE) disks for direct anal ysis of both fractions together. A lay ered filtering medium on top of the SPE disk allowed analysis of a 1-L effluent sample without clogging the disk; the medium and SPE disk were diluted together. The authors com pared dioxin and furan extraction from effluents, using the SPE disks with conventional methods, and found no statistical difference in the analysis. Moreover, the SPE method reduced sample preparation time 20%, reduced solvent use 70%, and completely eliminated the need for dichloromethane. (Anal. Chem. 1995,67(7), 1186-90)
MODELING PAH degradation Can two- or three-phase equilibrium partitioning models explain the ob served concentrations of polycyclic aromatic hydrocarbon (PAH) com pounds in sediment pore waters? S. E. McGroddy and J. W. Farrington studied pore waters in Boston Har bor sediments, which are heavily contaminated by PAH compounds. Results indicated that pore water PAH concentrations were signifi cantly lower than predicted by the equilibrium partitioning model. For example, only a fraction of phenanthrene concentrations in sediment (0.2-5%) readily partitioned into pore waters. Although different com pounds exhibited varying degrees of partitioning, total sediment PAH concentrations clearly were seques tered in a physicochemical form that is not readily available to equilib rium partitioning for 30-50 years. The authors suggest that PAH com pounds delivered with soot particles
A watershed approach to mercury transport J. P. Hurley and colleagues address the influence of watershed charac teristics on mercury transport mech anisms in Wisconsin river systems. They stress the importance of clean chemistry protocols in analyzing aqueous trace metal concentrations, especially when the results are used to evaluate contaminant levels in river systems. Using a Geographic Information System, the authors se lected watersheds with unique, ho mogenous characteristics. Total mean mercury concentrations gener ally were higher in spring than in fall—7.94 versus 3.45 ng/L, respec tively. Grouping by land use affected total mercury concentration yields. For example, in wetlands and for ested watersheds, total mercury fluxes were concentrated in the fil tered phase, but in agricultural wa tersheds, total mercury fluxes were related to particle loading. Monomethyl mercury yields were elevated in the wetlands/forested watersheds relative to those in agricultural sites. Yields also were correlated positively to percent wetlands surface area. (Environ. Sci. Technol., this issue, 1867-75)
are less available to partitioning into pore waters than petroleum-derived PAHs. (Environ. Sci. Technol. 1995, 29(6), 1599-1606)
RISK Societal decision making L. R. Keller and R. K. Sarin investi gated societal decision making in volving various risks and benefits. They evaluated the decision making on the final site choice of a hypo thetical hazardous waste facility by test subjects from three groups: arbi trators, negotiators, and jurors. Each group used distinct risk and benefit preferences to choose among several possible sites with different risk and benefit distributions. The negotiator and juror groups tended to balance community preferences whereas the arbitrator group balanced risks and benefits. The authors conclude that societal backgrounds affect decision making. (Risk Anal. 1995, 75(1), 4959)
Ecological risk tools Poorly managed ecological risk as sessment projects often resemble open-ended research studies and produce vague, unrelated results. B. K. Hope calls for application of project management tools to ecolog ical risk assessment. One manage ment tool integrates ecological risk assessment tasks from the scoping phase through completion of a base line risk assessment. A second tool incorporates ecological risk assess ment into remedy assessment and selection. Such management tools, Hope concludes, can produce practi cal, consistent risk assessments within budget and on schedule. (En viron. Professional 1995, 77(1), 9-19)
POLICY Environmental quality A society's environmental quality often declines with economic devel opment and later begins to improve as development progresses. A. S. Forrest drew on World Bank re search to identify a turning point in development for improved environ mental quality. Instead of a clear turning point, three factors—the economy's size, productive and consumptive capacities, and pollu tion control techniques—influence environmental quality. Forrest rec ommends manipulating the econ omy and requiring specific preven tion technologies to improve environmental quality without im peding development. (Environ. Fo rum 1995, 12(2), 24-31)
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SEDIMENTS Quality guidelines Sediment quality guidelines gener ally are more difficult to establish than water quality guidelines. E. R. Long and colleagues compared 89 sediment toxicity studies to deter mine guideline values for seven trace metals and 13 polynuclear aro matic hydrocarbons. Though less successful with two metals, two pes ticides, and PCBs, their method offers a rapid approach for developing guidelines from models, bioassays, and field surveys. The method is being used in Canada as a basis for develop ing regulatory guidelines. (Environ. Manage. 1995, 29(1), 81-97)
