Trace Metal Pollution in the Environment

Trace metals introduced to the environment from fuel combustion, incineration, and industrial emission sources are causing increasing concern to air pollution researchers. Several metals in urban air, including lead and vanadium, are associated with particles in the predominantly submicrometer diameter range thereby presenting an inhalation threat. There is also growing evidence that some metals emitted from stationary sources are concentrated in submicrometer sized particles which may pass through emission control devices. This report summarizes the concentration and size of trace metals in urban air, the concentration ranges found in selected fuels and emission sources, and describes the areas where further studies are needed.     

Summary of POHC Audit Results Using VOST and Bag Methods During RCRA Trial Burns

Audit materials containing Principal Organic Hazardous Constituents (POHCs) have been developed by EPA for use by Federal, State, and Local agencies or their contractors to assess the accuracy of measurement methods used during RCRA trial burn tests. Audit materials are currently available for 27 gaseous organics in five-, six-, seven-, and nine-component mixtures at ppb levels (7 to 10,000 ppb) in compressed gas cylinders in a balance gas of nitrogen. The logic used in selecting 27 gaseous organic compounds as audit materials and how these audit materials are successfully used in performance audits is described. Stability studies indicate that all of the organics tested (with the exception of ethylene oxide and propylene oxide below 10 ppb levels) are stable enough to be used as reliable audit materials. As of January 1990, 215 performance audits have been conducted to assess the accuracy of Volatile Organic Sampling Train (VOST) and bag measurement methods during or prior to RCRA trial burn tests. A summary of the audits conducted for each POHC, the measurement system audited, and the frequency of audits is described. The audit results obtained with audit gases are generally within ±50% of the audit concentrations.     

Connectivity between marine reserves and exploited areas in the philopatric reef fish Chrysoblephus laticeps (Teleostei: Sparidae)

‘No-take’ marine protected areas (MPAs) are successful in protecting populations of many exploited fish species, but it is often unclear whether networks of MPAs are adequately spaced to ensure connectivity among reserves, and whether there is spillover into adjacent exploited areas. Such issues are particularly important in species with low dispersal potential, many of which exist as genetically distinct regional stocks. The roman, Chrysoblephus laticeps, is an overexploited, commercially important sparid endemic to South Africa. Post-recruits display resident behavior and occupy small home ranges, making C. laticeps a suitable model species to study genetic structure in marine teleosts with potentially low dispersal ability. We used multilocus data from two types of highly variable genetic markers (mitochondrial DNA control region and seven microsatellite markers) to clarify patterns of genetic connectivity and population structure in C. laticeps using samples from two MPAs and several moderately or severely exploited regions. Despite using analytical tools that are sensitive to detect even subtle genetic structure, we found that this species exists as a single, well-mixed stock throughout its core distribution. The high levels of connectivity identified among sites support the findings of previous studies that have indicated that inshore MPAs are an adequate tool for managing overexploited temperate reef fishes. Even though dispersal of adult C. laticeps out of MPAs is limited, the fact that the large adults in these reserves produce exponentially more offspring than their smaller counterparts in exploited areas makes MPAs a rich source of recruits. We nonetheless caution against concluding that the lack of structure identified in C. laticeps and several other southern African teleosts can be considered to be representative of marine teleosts in this region in general. Many such species are represented in more than one marine biogeographic province and may be comprised of regionally adapted stocks that require individual management.     

Growth pattern of the sea urchin, Loxechinus albus (Molina, 1782) in southern Chile: evaluation of growth models

The growth pattern of Loxechinus albus in southern Chile was studied using size-at-age data obtained by reading growth bands on the genital plates. The scatter plots of sizes-at-age for samples collected in three different locations indicated that growth is linear between ages 2 and 10. Five different growth models, including linear, asymptotic and non-asymptotic functions, were fitted to the data, and model selection was conducted based on the Akaike information criteria (AIC) and the Bayesian information criteria (BIC). The AIC identified the Tanaka model as the most suitable for two of the three sites. However, the BIC led to the selection of the linear model for all zones. Our results show that the growth pattern of L. albus is different from the predominantly asymptotic pattern that has been reported for other sea urchin species.     

MODELKEY

The EU Water Framework Directive (WFD) requires the achievement of good ecological and chemical status in European river basins. However, evidence is increasing that a majority of European water bodies will not achieve this goal. Nutrient emissions and related eutrophication together with hydromorphological alterations have been suggested as the major driving forces of this insufficient ecological status. MODELKEY (511237 GOCE, FP6) provides strong evidence that toxic chemicals also affect the ecological status of European rivers. This was demonstrated in the case study rivers Elbe, Scheldt and Llobregat on different scales. This paper summarises key findings of MODELKEY including recommendations for WFD implementation. We ? provide evidence of toxic stress in aquatic ecosystems, ? provide evidence that impairment of ecological status results from impact of multiple stressors, ? suggest a tiered approach to assess impact of chemicals on ecological status, ? suggest a new approach for deriving candidate compounds for monitoring and prioritisation, ? call for consideration of bioavailability and bioaccumulation in chemical status assessments, ? suggest improvements for WFD water quality monitoring programmes, ? provide new integrated tools for basin-scale risk assessment and decision making, ? developed a Decision Support System to support river basin management. These key results will be presented in a series of ten integrated sections; for the scientific details please refer to publications listed on the MODELKEY website (http://www.modelkey.org/). This article also looks beyond MODELKEY and proposes a combination of MODELKEY diagnostic tools with recent ecological methods to further improve effectiveness of river basin management.     

Effects of rising temperature on pelagic biogeochemistry in mesocosm systems: a comparative analysis of the AQUASHIFT Kiel experiments

A comparative analysis of data, obtained during four indoor-mesocosm experiments with natural spring plankton communities from the Baltic Sea, was conducted to investigate whether biogeochemical cycling is affected by an increase in water temperature of up to 6?°C above present-day conditions. In all experiments, warming stimulated in particular heterotrophic bacterial processes and had an accelerating effect on the temporal development of phytoplankton blooms. This was also mirrored in the build-up and partitioning of organic matter between particulate and dissolved phases. Thus, warming increased both the magnitude and rate of dissolved organic carbon (DOC) build-up, whereas the accumulation of particulate organic carbon (POC) and phosphorus (POP) decreased with rising temperature. In concert, the observed temperature-mediated changes in biogeochemical components suggest strong shifts in the functioning of marine pelagic food webs and the ocean’s biological carbon pump, hence providing potential feedback mechanisms to Earth’s climate system.