Fate of 1,2,3,4,6,7,8-heptachlorodibenzofuran and pentachlorophenol during laboratory-scale anaerobic mesophilic sewage sludge digestion

The possibility of the formation of PCDDs and dechlorination of PCDFs during the anaerobic digestion of sewage sludge in laboratory scale digesters was investigated. Digesters were spiked with 1,2,3,4,6,7,8-HpCDF-13C(6) (240 ng/g organic matter (OM)) and pentachlorophenol (PeCP)-13C(6) (24 microg/g OM) and the output sludge monitored for 60 days. No dechlorination or formation of the labelled or native PCDD/Fs was observed. The detectable 1,2,3,4,6,7,8-HpCDF-13C(6) dechlorination yield was 0.0008-1% depending on homologue group and the detectable formation of OCDD yield was 0.00042% PeCP-13C(6). Preferential respiration of other, more bioavailable, substrates is suggested as the most plausible explanation for the lack of dechlorination. Formation of PCDDs from PeCP has been observed in aerobic environments but this study provides further evidence that it is not a precursor for formation during anaerobic digestion.     

Estimating the benefits of recreation under conditions of congestion congestion

In a recent issue of J. Environ. Econ. Manag. Wetzel showed that the standard travel cost technique will understate recreation benefits under congested conditions because changes in entry fee lead to lowered congestion levels. This comment indicates that benefit projections derived from the travel cost procedure may theoretically overstate the true value of recreation if rising income levels shift the demand curve upwards but fail to account for the contrary effect of increased congestion. The magnitude and direction of the bias that results from omission of a congestion variable is, however, indeterminate when standard econometric techniques are used to develop benefit projections.     

Polymodal foraging in adult female loggerheads (Caretta caretta)

To determine whether loggerhead turtles (Caretta caretta) nesting in southeastern USA exhibit polymorphic foraging strategies, we evaluated skin samples for stable isotopes of carbon (δ¹³C) and nitrogen (δ¹⁵N) from 310 loggerheads from four locations on the east coast of Florida and epibionts from 48 loggerheads. We found a dichotomy between a depleted δ¹³C cluster and an enriched δ¹³C cluster. Epibionts from oceanic/pelagic or neritic/benthic habitats were largely consistent with this dichotomy. The bimodal distribution of δ¹³C could reflect a bimodal foraging strategy or—because of the potential for confounding among four gradients of δ¹³C in marine environments—a polymodal foraging strategy. We integrate our results with results from other stable isotope studies, satellite telemetry, and flipper tags to evaluate potential foraging strategies. Understanding foraging strategies is essential for development of management plans for this endangered species that has suffered a 43% population decline over the last decade.     

Observations on the short-term movements and behaviour of whale sharks (Rhincodon typus) at Ningaloo Reef, Western Australia

The short-term movements and behaviour of whale sharks (Rhincodon typus Smith, 1828) during March 1994 and April 1997 are reported from data collected by acoustic tracking and archival tags at Ningaloo Reef on the north west coast of Western Australia. Sharks were tracked for up to 26 h and generally swam slowly at ≃0.7 m s⁻¹ parallel to the reef edge; occasionally they swam in a wide arc adjacent to passes in the reef. All tracked sharks made regular dives through the water column, mostly from the surface to near the bottom. These dives did not appear to be related to hydrographic features, and the sharks were probably searching the water column for food. Most sharks were accompanied by other fishes, usually the golden trevally Gnathanodon speciosus. Received: 19 January 1999 / Accepted: 22 June 1999     

Assessing Linkages in Stream Habitat,Geomorphic Condition,and Biological Integrity Using a Generalized Regression Neural Network

Watershed managers often use physical geomorphic and habitat assessments in making decisions about the biological integrity of a stream, and to reduce the cost and time for identifying stream stressors and developing mitigation strategies. Such analysis is difficult since the complex linkages between reach‐scale geomorphic and habitat conditions, and biological integrity are not fully understood. We evaluate the effectiveness of a generalized regression neural network (GRNN) to predict biological integrity using physical (i.e., geomorphic and habitat) stream‐reach assessment data. The method is first tested using geomorphic assessments to predict habitat condition for 1,292 stream reaches from the Vermont Agency of Natural Resources. The GRNN methodology outperforms linear regression (69% vs. 40% classified correctly) and improves slightly (70% correct) with additional data on channel evolution. Analysis of a subset of the reaches where physical assessments are used to predict biological integrity shows no significant linear correlation, however the GRNN predicted 48% of the fish health data and 23% of macroinvertebrate health. Although the GRNN is superior to linear regression, these results show linking physical and biological health remains challenging. Reasons for lack of agreement, including spatial and temporal scale differences, are discussed. We show the GRNN to be a data‐driven tool that can assist watershed managers with large quantities of complex, nonlinear data.     

On the potential of iPhone significant location data to characterize individual mobility for air pollution health studies

● We evaluated the accuracy of iPhone data in capturing time-activity patterns. ● iPhone data captured the most important microenvironments and time spent in them. ● iPhone data also accurately captured daily exposure to ambient PM pollution. ● A considerable fraction of the population in the USA may have iPhone data available. ● iPhone data has great potential in air pollution health studies. In many air pollution health studies, the time-activity pattern of individuals is often ignored largely due to lack of data. However, a better understanding of this location-based information is expected to decrease uncertainties in exposure estimation. Here, we showcase the potential of iPhone’s Significant Location (iSL) data in capturing the user’s historical time-activity patterns in order to estimate exposure to ambient air pollutants. In this study, one subject carried an iPhone in tandem with a reference GPS tracking device for one month. The GPS device recorded locations in 10 second intervals while the iSL recorded the time spent in locations the subject visited frequently. Using GPS data as a reference, we then evaluated the accuracy of iSL data in capturing the subject’s time-activity patterns and time-weighted air pollution concentration within the study time period. We found the iSL data accurately captured the time the subject spent in 16 microenvironments (i.e. locations the subject visited more than once), which was 93% of the time during the study period. The average error of time-weighted aerosol optical depth value, a surrogate of particle pollution, is only 0.012%. To explore the availability of iSL data among iPhone users, an online survey was conducted. Among the 349 surveyed participants, 72% of them have iSL data available. Considering the popularity of iPhones, iSL data may be available for a significant portion of the general population. Our results suggest iSL data have great potential for characterizing historical time-activity patterns to improve air pollution exposure estimation.     

Habitat inventory at a regional scale: a comparison of estimates of terrestrial Broad Habitat cover from stratified sample field survey and full census field survey for Wales, UK

Estimates of terrestrial Broad Habitat cover for Wales from the Countryside Survey 2000 stratified sample field mapping programme in Britain are compared with the findings of a full census field mapping project, the Habitat Survey of Wales. The Countryside Survey sampling regime comprised a stratified random sample of 1 km squares [corrected] covering <0.5% of the land surface. Comparative assessment indicates that although few of the sample-derived estimates for individual Broad Habitats are within 30% of the full census survey results, relative extents accord with data from the complete census survey for all Broad Habitats apart from Arable & Horticultural. The accuracy of this estimate is improved when the national boundary of Wales is taken into account in the sample stratification scheme. It is suggested that cultural land-use differences between countries render cropland habitat extent less predictable from physical environmental parameters than semi-natural habitat extent. It is also shown that the precision of sample-derived cover estimates is influenced by habitat pattern: the error term associated with habitats of broadly equal extent is greater for those with the most clumped distributions.     

Closing the gap: a research agenda to accelerate the adoption and effective use of proven older adult fall prevention strategies

IntroductionTo make an impact on the public's health, evidence-based interventions must be disseminated broadly, supported by training and technical assistance, adopted widely, and implemented as designed. Many effective older adult fall prevention interventions have been identified, but too few have gained wide community acceptance and little is known about the best ways to encourage their broader use. Therefore, as in many other fields, fall prevention suffers from a wide gap between scientific discoveries and their everyday use.MethodThis article articulates the key activities embedded in Step 4 of the public health model—specifically translation and dissemination to ensure widespread adoption and use—in order to illuminate critical research needs in older adult fall prevention.ConclusionsThese needs, if addressed, will help close the gap between research and practice.     

Addressing the Impact of Atmospheric Nitrogen Deposition on Western European Grasslands

There is a growing evidence base demonstrating that atmospheric nitrogen deposition presents a threat to biodiversity and ecosystem function in acid grasslands in Western Europe. Here, we report the findings of a workshop held for European policy makers to assess the perceived importance of reactive nitrogen deposition for grassland conservation, identify areas for policy development in Europe and assess the potential for managing and mitigating the impacts of nitrogen deposition. The importance of nitrogen as a pollutant is already recognized in European legislation, but there is little emphasis in policy on the evaluation of changes in biodiversity due to nitrogen. We assess the potential value of using typical species, as defined in the European Union Habitats Directive, for determining the impact of nitrogen deposition on acid grasslands. Although some species could potentially be used as indicators of nitrogen deposition, many of the typical species do not respond strongly to nitrogen deposition and are unlikely to be useful for identifying impact on an individual site. We also discuss potential mitigation measures and novel ways in which emissions from agriculture could be reduced.