when assessing the soil-to-indoor-air exposure pathway. They suggest that the treatment of soil moisture behavior can be simplified if accurate soil moisture data are used. (Environ. Toxicol. Chem. 1997, 16, 25972604)
MEASUREMENTS Pesticide detection method The analysis of trace amounts of pesticide residues in natural waters and sediments requires sensitive, selective measurement methods. I. Ferrer and colleagues report the detection of part-per-trillion levels of pesticides in sediments and natural waters using low preconcentration volumes and on-line coupling of immunosorbents with liquid chromatography/atmospheric pressure chemical ionization mass spectrometry. A test of the method used sample preparation cartridges prepacked with silica and anti-atrazine or antichlorotoluron antibodies to extract several triazine and phenylurea herbicides from water samples The absence of sample matrix interferences
Soil organic matter controls sorption The ability of soil organic matter to sorb anthropogenic organic pollutants may be limited by competition from naturally occurring, low molecular weight organic compounds. In studies of natural soil suspensions, B. Xing and J. Pignatello showed that sorption of naturally occurring aromatic acids and anthropogenic chlorinated compounds are both characterized by nonlinear sorption isotherms. This implies that soil organic matter controls sorption. Natural and anthropogenic compounds exhibited direct competition for sorption sites These results suggest that naturally occurrinc- low molecular weight organic compounds can increacp the mnhility and bioavailability of anthmnnnenic organic nnllutants in the
environment iFnviron Tprhnnl ,his issue ,in 611-619)
to higher production of methylmercury at greater water depth. [Environ. Toxicol. Chem. 1997, 16 (12), 2489-2493)
indicated good selprtivity from the immunosorbents An interlabo ratory study was donp to valiHatp the mpthod (Anal Chem 1197 fi9 f??)
MODELING PCB partition coefficients
METALS Mercury deposition Mercury concentrations in historical samples obtained from land-based sites, such as lake sediments, reflect global and regional deposition trends. Reasoning that seabirds from remote islands are affected only by global atmospheric deposition trends, L. Monteiro and R. Furness analyzed recent and historical seabird feather samples for mercury content. The analysis included measurements of mercury concentrations in the birds over the past 100 years and results indicated an increase in mercury concentrations in feathers Avian species that feed primarily on fish from middle depths showed a higher rate of increase than birds that feed on near-surface fish The authors attribute this rp^ult
Prediction of the environmental fate of semivolatile organic chemicals requires knowledge of how they partition to environmental compartments. The octanol-air partition coefficient, ^TOA, is used as a measure of partitioning between chemicals in the gas phase and the terrestrial environment. P. Komp and S. McLachlan used a fugacity meter to investigate partitioning by PCBs between air and 1-octanol. Measured values of K exponentially proportional to the reciprocal temperature were higher than valcalculated from the octanolwater partition coefficient and Henry's law constants and they were used to calculate the enthalDV of phase chanffp which ranapH from 71 to 93 kj/mol Results of this research enable reliable nrerliction of K for all PCB ronppners (Fnvrrnn Tnrirnl Chpm 1997 16(^?^ 2433-?4371
Bioconcentration ratios A bioconcentration ratio—the ratio of the concentration of a compound in plants or animals to its concentration in an environmental medium— can be predicted by various estimation methods. D. Dowdy and T. McKone compared the reliability of the molecular connectivity index (MCI) and the octanol-water partition coefficient as predictors of bioconcentration ratios. Results reveal that the MCI is more precise, easy to use, and cost-effective for predicting bioconcentration of compounds from soil to above-ground vegetation The T^CI Wcis slightly better than the octanol-water coefficient for predicting soil solution to plant root uptake and was less precise for predicting the uptake of compounds into plants from than was thp octanol-water coeffirient or thp nrtanol-air nartition m pfficipnt (Fnuirnn Tnrirnl Chem 1997 16 ?44R-?4c>fil
RISK Views on ecorisk Knowledge of how stakeholders view ecological risk assessment may provide a basis for improving the technique. M. Power and S. Adams solicited, assembled, and summarized six evaluations of ecological risk assessment written by practitioners, advocates, and critics. A major concern is whether methodological simplifications required for regulatory and practical reasons lead to inaccurate assessments and incorrect management decisions. Most respondents agreed on a need for increased validation better definition of problems and scope and general improvements in the underlying knowledge base An ecological risk assessment matrix that relates 13 key issues to resnondents' views indicates the diversp nature of stakeholder views 1997
803-
830)
Data-derived uncertainty The use of default uncertainty factors in the dose-response assessment of noncancer toxicity is common practice, but data-derived uncertainty factors increasingly are being used to establish safe dose
MARCH 1, 1998 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 1 4 7 A
