Characterisation of potentially genotoxic compounds in sediments collected from United Kingdom estuaries

The mutagenic activity bioassay Mutatox was used to assess the mutagenic activity associated with sediments collected from five UK estuaries. Assays were performed on extracts of sediment pore water and residual particulate material isolated from sediment samples collected from the rivers Tyne, Tees, Mersey, and Thames as well as Southampton Water. No mutagenic activity was associated with the pore water extracts, however, 7 of the 28 organic solvent extracts of sediment particulate material contained potential genotoxins. By using Mutatox in association with bioassay-directed fractionation, attempts were made to identify the mutagenic compounds present in the extracts. The fractionation procedure used normal phase solid phase extraction, C18 reverse phase HPLC and cyano/amino bonded silica normal phase HPLC. GC-MS (EI and NICI) analysis was used to identify polycyclic aromatic hydrocarbons (PAH), alkyl substituted PAH, nitro-polycyclic aromatic compounds (nitro-PACs), polycyclic aromatic ketones, oxygenated-PACs, and other known mutagens contributing to the genotoxicity measured in the samples. Some potentially genotoxic compounds remain unidentified.     

Tibial hemimelia syndrome: Prenatal diagnosis by real-time ultrasound

The tibial hemimelia syndrome is a rare autosomal dominant condition associated with limb deficiencies. We recently diagnosed this condition in a pregnancy at 16·5 weeks' gestation by ultrasound and a positive family history. To our knowledge, this represents the first case to be detected prenatally.     

Toxic equivalency factors for PAH and their applicability in shellfish pollution monitoring studies

Fish and shellfish are exposed to a wide range of polycyclic aromatic hydrocarbons (PAH) following oil spills at sea, and can become contaminated as a result. Finfish have a more effective mixed-function oxidase enzyme system than shellfish, and are therefore able to metabolise and excrete PAH more effectively than the invertebrates. Thus, contamination by high-molecular weight PAH, including those with carcinogenic potential and so of concern with regard to human consumers, is therefore usually observed in shellfish, and particularly in bivalve molluscs. Oil spills are not the sole source of PAH, however, as parent compounds are also generated by a wide range of combustion processes. In this paper, consideration is given to monitoring data gathered following recent oil spills (both of crude oil and diesel fuel), alongside data from other studies. These include studies conducted around a former gasworks site and downstream of an aluminium smelter in the UK, and from mussel monitoring studies undertaken in the UK and the USA (including the Exxon Valdez oil spill and the National Status and Trends programme), and in other countries in Europe. For comparative purposes the PAH concentrations are summed and also expressed as benzo[a]pyrene equivalents, their relative concentrations being weighted in relation to the carcinogenic potential of individual PAH compounds using toxic equivalency factors (TEF). Our aim was to assess the utility of this approach in fishery resource monitoring and control following oil spills. Certainly this approach seems useful from the data assessed in this study. and the relative ranking of the various studies seems to reflect the relative degree of concern for human consumers due to the differing contamination sources. As a simple tool for control purposes it is equally applicable to PAH derived from oil spills, and from industrial and combustion sources.     

Synergy or substitution? The interactive effects of insiders' fairness and support and organizational socialization tactics on newcomer role clarity and social integration

Drawing on fairness heuristics theory (Lind, 2001) and cue consistency theory (Maheswaran & Chaiken, 1991; Slovic, 1966), we test a moderated mediation model that examines whether the institutionalization of organizational socialization tactics enhances or constrains the beneficial effects of supervisory and coworker‐referenced justice and support on newcomer role clarity and social integration. The findings of a three‐wave study of 219 French newcomers show that although institutionalized tactics strengthen the positive indirect effects of supervisory interpersonal and informational justice on role clarity, via perceived supervisor support, it also acts as a substitute that weakens the positive indirect effect of coworker‐referenced interpersonal justice on social integration, via perceived coworker support. Implications of the findings for socialization research and practice are discussed.     

Ambient Air Arsenic Levels Along the Texas-Mexico Border

The Texas-Mexico border region Is one of the most rapidly developing areas in the state. Unprecedented economic and demographic growth Is placing stress on a system already overburdened with air, water, waste, and public health problems. This paper reports the results of an initial survey of the past and present ambient air levels of arsenic along the Texas side of the border. Ambient air arsenic levels have increased over time, exhibit seasonal variations, and are higher In specific areas when compared to the rest of the state. Five of the 20 areas in Texas having the highest 24-hour levels of arsenic are found along the border. In areas where emissions have been significantly reduced at the source, arsenic levels remained high In the environment for over two years. This provides a potential continuum for human exposure. The results of this study emphasize the need for bi-national development and implementation of air quality control programs along the Texas-Mexico border.     

Diurnal variation in chlorophyll fluorescence of Thalassia testudinum seedlings in response to controlled salinity and light conditions

Diurnal variability in chlorophyll fluorescence caused by dynamic irradiance conditions is an important issue when using pulse amplitude modulation fluorometry to measure physiological conditions of plants at the landscape scale. We examined the use of slopes and y-intercepts of diurnal effective photochemical efficiency of photosystem II (PSII) (ΔF/F _m′) versus photosynthetically active radiation (PAR) regressions in addition to direct measurements of maximum photochemical efficiencies of PSII (F _v/F _m) values to assess physiological status of Thalassia testudinum seedlings in a controlled mesocosm study. Seedlings were exposed to two light treatments (full sun and 50–70 % light reduction) and three salinity treatments (20, 35, and 50). Measurements were taken at 0600, 0900, 1200, 1500, 1800, and 2100 hours in order to assess the diurnal variation in photochemical efficiency of PSII and PAR, with measurements at 2100 providing F _v/F _m. Results indicated significant effects of light and salinity on regression y-intercepts and measured F _v/F _m values. Shaded seedlings had higher values for both parameters, suggesting low-light acclimation. The highest salinity treatment resulted in significant reductions for both parameters, suggesting stress. Stress was also indicated by significant reductions in both seedling leaf growth and mean differences between seedling leaves and media osmolalities in the hypersaline treatments (152.0 ± 26.4 vs. 630 ± 40.2 mmol kg^?1 for the control treatments). Slopes of ΔF/F _m′ versus PAR significantly differed with varying light treatments, with full sun seedlings exhibiting shallower slopes than shaded seedlings, indicating higher efficiency of dissipation of excess energy (photoprotection). These experimental results confirm field data suggesting that diurnal ΔF/F _m′ versus PAR regressions are responsive to changes in the physiological status of T. testudinum and that the y-intercepts of diurnal regressions may be used as a proxy for F _v/F _m.     

From Management to Negotiation: Technical and Institutional Innovations for Integrated Water Resource Management in the Upper Comoé River Basin, Burkina Faso

This study focuses on the potential role of technical and institutional innovations for improving water management in a multi-user context in Burkina Faso. We focus on a system centered on three reservoirs that capture the waters of the Upper Comoé River Basin and servicing a diversity of users, including a sugar manufacturing company, a urban water supply utility, a farmer cooperative, and other downstream users. Due to variable and declining rainfall and expanding users’ needs, drastic fluctuations in water supply and demand occur during each dry season. A decision support tool was developed through participatory research to enable users to assess the impact of alternative release and diversion schedules on deficits faced by each user. The tool is meant to be applied in the context of consultative planning by a local user committee that has been created by a new national integrated water management policy. We contend that both solid science and good governance are instrumental in realizing efficient and equitable water management and adaptation to climate variability and change. But, while modeling tools and negotiation platforms may assist users in managing climate risk, they also introduce additional uncertainties into the deliberative process. It is therefore imperative to understand how these technological and institutional innovations frame water use issues and decisions to ensure that such framing is consistent with the goals of integrated water resource management.     

Swimming behavior of juvenile anchovies (<Emphasis Type="Italic">Anchoa</Emphasis> spp.) in an episodically hypoxic estuary: implications for individual energetics and trophic dynamics

Diel swimming behaviors of juvenile anchovies (Anchoa spp.) were observed using stationary hydroacoustics and synoptic physicochemical and zooplankton profiles during four unique water quality scenarios in the Neuse River Estuary, NC, USA. Vertical distribution of fish was restricted to waters with DO greater than 2.5 mg O₂ l⁻¹, except when greater than 70% of the water column was hypoxic and a subset of fish were occupying water with 1 mg O₂ l⁻¹. We made the prediction that an individual fish would select a swim speed that would maximize net energy gain given the abundance and availability of prey in the normoxic waters. During the day, fish adopted swim speeds between 7 and 8.8 bl s⁻¹ that were near the theoretical optimum speeds between 7.0 and 8.0 bl s⁻¹. An exception was found during severe hypoxia, when fish were swimming at 60% above the optimum speed (observed speed = 10.6 bl s⁻¹, expected = 6.4 bl s⁻¹). The anchovy is a visual planktivore; therefore, we expected a diel activity pattern characteristic of a diurnal species, with quiescence at night to minimize energetic costs. Under stratified and hypoxic conditions with high fish density coupled with limited prey availability, anchovies sustained high swimming speeds at night. The sustained nighttime activity resulted in estimated daily energy expenditure over 20% greater than fish that adopted a diurnal activity pattern. We provide evidence that the sustained nighttime activity patterns are a result of foraging at night due to a lower ration achieved during the day. During severe hypoxic events, we also observed individual fish making brief forays into the hypoxic hypolimnion. These bottom waters generally contained higher prey (copepod) concentrations than the surface waters. The bay anchovy, a facultative particle forager, adopts a range of behaviors to compensate for the effects of increased conspecific density and reduced prey availability in the presence of stratification-induced hypoxia.