Research Watch: Data-derived uncertainty

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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

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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

CHAIR IN RESOURCE ENGINEERING University of Auckland New Zealand Department of Civil & Resource Engineering School of Engineering VACANCY 924EST The University of Auckland is the largest of the New Zealand universities with about 25,000 students. Auckland, the City of Sails, has an attractive living environment. This is a newly established Chair. A degree course in resource engineering has recently been introduced, which reflects the Department's commitment to produce graduates who will assist society to move towards a sustainable future. It contains wide ranging papers in environmental topics, water resources and mineral resources, which build on core engineering papers. Applications are sought from those with exceptional teaching, research and/or professional achievements in resource engineering, and or environmental engineering, who will provide leadership in education and research in resource and environmental engineering. Civil and Resource Engineering is one of five departments in the School of Engineering and has strong research interests in a wide range of areas. It has 24 academic staff and 13 technical and administrative staff. The undergraduate programmes contain strong design and laboratory activities, and the Department has close ties with New Zealand industry. Further information and Conditions of Appointment should be obtained from the Academic Appointments Office, telephone 64-9-373-7599 ext 5789, fax 64-9-373-7023, email: appointments© auckland.ac.nz, or from our website: www.auckland.ac.nz/ appointments/. If mailing your application three copies must reach the Academic Appointments Section, The University of Auckland, Private Bag 92019, Auckland, New Zealand, by 30 March 1998. Please quote Vacancy Number 924EST in all correspondence. ASSISTANT REGISTRAR, ACADEMIC APPOINTMENTS

levels. M. Dourson and colleagues surveyed risk assessment practices of government organizations. Results indicate that although default uncertainty factors are still predominantly used to assess risk, the frequency of use of data-derived uncertainty factors rather than default uncertainty factors is significant. EPA used dataderived uncertainly factors in developing 392 reference concentration and reference dose values. Case studies indicate underlying assumptions used in deriving nondefault uncertainty factors {Hum Ecol Risk Assess 1997 3 (4) 579-589)

TECHNOLOGY CFC destruction To protect the ozone layer and prevent greenhouse gas buildup, large stockpiles of CFCs must be destroyed. H. Ueno and co-workers examined the destruction of these compounds in a working cement kiln with a gas residence time of 6-7 seconds and an operating temperature of 1450 °C. Results indicate that CFCs can be completely destroyed under normal operating conditions. Hydrogen chloride and hydrogen fluoride produced by decomposition of CFC feedstocks were absorbed by the alkaline cement material. Monitoring of secondary pollutants such as phosgene and dioxins showed no significant increases during the destruction experiments (J Air Waste Assoc 1997 47 fill 1 pon_ i yyw

WASTEWATER Phosphorus removal During application of the enhanced biological phosphorus removal process, a technique widely used to remove phosphorus from wastewater, a relationship has been observed between sludge carbohydrate content and phosphorus removal performance. Y. Liu studied this relationship using two activated sludgesequencing batch reactors. Glucose and acetate were used as the main organic substrates. Phosphorus removal was excellent for sludge carbohydrate content between 8 and

1 4 8 A • MARCH 1, 1998 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS

10%, but it declined as the sludge carbohydrate content increased beyond this range. The study indicates that the sludge carbohydrate content is an important process control parameter. (Water Environ. Res. 1997, 69, 1290-1295)

Surfactant performance study Surfactants are often used to enhance the biodegradation of low-aqueoussolubility organic compounds at hazardous waste sites. L. Figueroa and colleagues evaluated the biodegradation of two non-ionic surfactants, Neodol 91-8 and Makon 12, at concentrations of 0.01%, 0.025%, and 0.05% in an activated sludgesequencing batch reactor. High rates of degradation were achieved for surfactant concentrations of