Grain size partitioning of platinum-group elements in road-deposited sediments: implications for anthropogenic flux estimates from autocatalysts

Twelve road-deposited sediment samples were analyzed for platinum-group elements (PGEs) and Pb in the <63 microm fraction of an urban watershed in Hawaii. Three samples were further fractionated into five size classes, from 63-125 microm to 1000-2000 microm, and these were analyzed for PGEs and Pb. Concentrations in the <63 microm fraction reached 174 microg/kg (Pt), 101 microg/kg (Pd), 16 microg/kg (Rh), and 1.3 microg/kg (Ir). Enrichment ratios followed the sequence Rh>Pt=Pd>Ir. Iridium was geogenic in origin, while the remaining PGEs indicated significant anthropogenic contamination. Palladium, Pt and Rh concentrations and enrichment signals were consistent with PGE bivariate ratios and PGE partitioning in three-way catalysts. Size partitioning indicated that the <63 microm fraction had the lowest PGE concentrations and mass loading percentages. These data suggest that autocatalyst PGE flux estimates into the environment will be significantly underestimated if only a fine grain size fraction is analyzed.     

Reviewing the framework for dealing with urban environmental problems

It is now widely accepted that there are problems with the state of urban environments globally. This paper presents the commonly used approaches for dealing with environmental problems, which have been categorised into target, top-down, market-driven and participative. The problems with these approaches are discussed, and the significance of participative approaches in dealing with environmental problems at the local scale is highlighted. The paper questions the basis underlying these approaches, and concludes that a new framework is needed to provide fresh approaches for dealing with environmental problems.     

Toward pristine biomass: reef fish recovery in coral reef marine protected areas in Kenya.

Identifying the rates of recovery of fish in no-take areas is fundamental to designing protected area networks, managing fisheries, estimating yields, identifying ecological interactions, and informing stakeholders about the outcomes of this management. Here we study the recovery of coral reef fishes through 37 years of protection using a space-for-time chronosequence of four marine national parks in Kenya. Using AIC model selection techniques, we assessed recovery trends using five ecologically meaningful production models: asymptotic, Ricker, logistic, linear, and exponential. There were clear recovery trends with time for species richness, total and size class density, and wet masses at the level of the taxonomic family. Species richness recovered rapidly to an asymptote at 10 years. The two main herbivorous families displayed differing responses to protection, scarids recovering rapidly, but then exhibiting some decline while acanthurids recovered more slowly and steadily throughout the study. Recovery of the two invertebrate-eating groups suggested competitive interactions over resources, with the labrids recovering more rapidly before a decline and the balistids demonstrating a slower logistic recovery. Remaining families displayed differing trends with time, with a general pattern of decline in smaller size classes or small-bodied species after an initial recovery, which suggests that some species- and size-related competitive and predatory control occurs in older closures. There appears to be an ecological succession of dominance with an initial rapid rise in labrids and scarids, followed by a slower rise in balistids and acanthurids, an associated decline in sea urchins, and an ultimate dominance in calcifying algae. Our results indicate that the unfished "equilibrium" biomass of the fish assemblage > 10 cm is 1100-1200 kg/ha, but these small parks (< 10 km2) are likely to underestimate pre-human influence values due to edge effects and the rarity of taxa with large area requirement, such as apex predators, including sharks.     

ESTABLISHING WATERSHED MANAGEMENT IN LAW: NEW ZEALAND'S EXPERIENCE1

ABSTRACT: New Zealand is one of the first countries in the world to enshrine the concept of watershed management in law, through institutional arrangements and the Resource Management Act of 1991 ‐ a law constructed on a watershed management legacy begun in 1941. This paper outlines the development of New Zealand's Resource Management Act (as it applies to water management) and the lessons that have been learned in its implementation.     

Diving of the sea snakePelamis platurus in the Gulf of Panamá

Fifteen yellow-bellied sea snakes,Pelamis platurus, fitted with pressure-sensitive ultrasonic transmitters, were tracked in the Gulf of Panamá during 1983–1985. Snakes spent up to 99.9% ( = 87%) of the tracking time under water and dived to 50 m. The maximum voluntary submergence time observed was 213 min, and of 202 complete dives logged, 19 exceeded 90 min. Dive durations of tracked snakes were typically longer than expected, based upon their estimated body-oxygen stores, and some were even longer than the reported survival times of forceably submerged snakes. Snakes, however, dived repeatedly and did not spend long periods at the surface between dives, suggesting that they did not develop an oxygen deficit during diving. Diving snakes may be able to avoid anaerobiosis by having a reduced metabolic rate, an enhanced rate of cutaneous oxygen uptake, or both. Surface conditions and subsurface temperatures influence the diving behavior ofP. platurus. Laboratory experiments in Panamá indicated that a larger number of snakes were submerged when surface water was turbulent. During February and March, the period of dry season upwelling in the Gulf of Panamá, sea snakes were found to avoid cooler, subsurface water and to make significantly shallower dives: mean maximum depth 6:8 m (n=76) in contrast to a mean maximum depth of 15.1 m (n=147) during the wet season. The dives during the dry season tended to be of shorter duration, with 44% lasting less than 15 min, compared to only 19% of the dives recorded during the wet season being completed in less than 15 min. General avoidance of subsurface temperatures cooler than 19°C was confirmed by laboratory experiments in the 10 m-deep tank at Scripps Institution of Oceanography.     

Estimation and comparison of night-time OH levels in the UK urban atmosphere using two different analysis methods

Night-time OH levels have been determined for UK urban surface environments using two methods,the decay and steady state approximation methods.Measurement data from the UK National Environmental Technology Centre archive for four urban sites(Bristol,Harwell,London Eltham and Edinburgh) over the time period of 1996 to 2000 have been used in this study.Three reactive alkenes,namely isoprene,1,3-butadiene and trans-2-pentene were chosen for the calculation of OH levels by the decay method.Hourly measurements o...     

Quantifying sediment-associated metal dispersal using Pb isotopes: Application of binary and multivariate mixing models at the catchment-scale

In this study Pb isotope signatures were used to identify the provenance of contaminant metals and establish patterns of downstream sediment dispersal within the River Maritsa catchment, which is impacted by the mining of polymetallic ores. A two-fold modelling approach was undertaken to quantify sediment-associated metal delivery to the Maritsa catchment; employing binary mixing models in tributary systems and a composite fingerprinting and mixing model approach in the wider Maritsa catchment. Composite fingerprints were determined using Pb isotopic and multi-element geochemical data to characterize sediments delivered from tributary catchments. Application of a mixing model allowed a quantification of the percentage contribution of tributary catchments to the sediment load of the River Maritsa. Sediment delivery from tributaries directly affected by mining activity contributes 42-63% to the sediment load of the River Maritsa, with best-fit regression relationships indicating that sediments originating from mining-affected tributaries are being dispersed over 200 km downstream.