Particulate sulfur species in the water column of the Cariaco Basin

The biogeochemistry of iron sulfide minerals in the water column of the Cariaco Basin was investigated in November 2007 (non-upwelling season) and May 2008 (upwelling season) as part of the on-going CARIACO (CArbon Retention In A Colored Ocean) time series project. The concentrations of particulate sulfur species, specifically acid volatile sulfur (AVS), greigite, pyrite, and particulate elemental sulfur, were determined at high resolution near the O₂/H₂S interface. In November 2007, AVS was low throughout the water column, with the highest concentration at the depth where sulfide was first detected (260 m) and with a second peak at 500 m. Greigite, pyrite, and particulate elemental sulfur showed distinct concentration maxima near the interface. In May 2008, AVS was not detected in the water column. Maxima for greigite, pyrite, and particulate elemental sulfur were again observed near the interface. We also studied the iron sulfide flux using sediment trap materials collected at the Cariaco station. Pyrite comprised 0.2-0.4% of the total particulate flux in the anoxic water column, with a flux of 0.5-1.6 mg S m⁻² d⁻¹.Consistent with the water column concentration profiles for iron sulfide minerals, the sulfur isotope composition of particulate sulfur found in deep anoxic traps was similar to that of dissolved sulfide near the O₂/H₂S interface. We conclude that pyrite is formed mainly within the redoxcline where sulfur cycling imparts a distinct isotopic signature compared to dissolved sulfide in the deep anoxic water. This conclusion is consistent with our previous study of sulfur species and chemoautotrophic production, which suggests that reaction of sulfide with reactive iron is an important pathway for sulfide oxidation and sulfur intermediate formation near the interface. Pyrite and elemental sulfur distributions favor a pathway of pyrite formation via the reaction of FeS with polysulfides or particulate elemental sulfur near the interface. A comparison of thermodynamic predictions with actual concentration profiles for iron sulfides leads us to argue that microbes may mediate this precipitation.     

Emergency preparedness and planning for nuclear power plant accidents

The current level of emergency preparedness and planning for off-site releases of radioactivity from nuclear power plants in the United States and public reactions to it are reviewed. The major assumptions in these plans involving the responses of the public are highlighted and provide the context for a critique of such plans. Five major deficiencies in the planning efforts are discussed in detail. As currently developed, emergency response plans are far short of insuring maximum protection of the public health and safety of residents living around these facilities. More importantly, the plans simply may not work if implemented.     

Community resilience,natural hazards,and climate change: Is the present a prologue to the future?

ABSTRACT

The nexus of natural hazards, climate change, and community resilience poses both conceptual and methodological challenges. One key consideration is the underlying notion of dynamic change or transformation in the systems that affect community resilience—social systems, natural systems, technological systems—and the degree to which the interdependencies influence who is resilient, to what, where, and to whom. The article examines community resilience from the broad perspective of affluent societies and illustrates the considerable variability in both the temporal and spatial nature of community resilience to natural hazards in the short term, and climate changes in the longer term, especially in more affluent societies. The author finds that, given the rapidity of environmental, social, economic, political, technological, and cultural changes, present circumstances and remedies may not be adequate predictors or precursors of future conditions. She concludes that the challenges associated with community resilience, natural hazards, and climate change require transformational thinking and action if achievements are to be made in terms of significant disaster risk reduction and any semblance of a sustainable future when extreme weather events will be the norm, not the exception.     

THE NATIONAL PATTERN OF AIRBORNE TOXIC RELEASES

Incident-specific data reveal the spatial patterns of two major classes of acute toxic airborne releases in the United States (1982–86): rural agricultural and urban industrial. Rural (primarily truck transport) incidents dominate the distribution in the western US, while rail incidents and fixed site incidents dominate in the east. Using a combination of cartographic and statistical analyses, risk and mitigation measures were calculated to identify high-hazard and low-hazard states. Risk factors, primarily numbers of chemical firms and rail miles per state, best predict the frequency of incidents and their resulting spatial pattern.     

The forgotten casualties: women, children, and environmental change.

The author posits that women and children bear a disproportionate burden of environmental degradation and are in the worst position to mitigate the consequences of deteriorating environmental conditions. This article discusses the concept of environmental equity or fairness and its sociospatial impacts and the different adjustments made by women and children. Environmental equity is both an outcome and a process. Process equity includes the underlying causes of uneven distributions of resources. The 1992 Rio Declaration on Environment and Development defines 27 specific principles that broadly follow three forms of equity: social equity, generational equity, and procedural equity. Social equity is defined as the role of social, economic, and political forces in resource consumption and environmental degradation. Environmental risk is related to locational criteria such as cheap land and transportation access and by the social geography of places. Hazardous waste dumping is used to illustrate inequitable waste disposal in developing countries such as Brazil, Mexico, Nigeria, Lebanon, Syria, Venezuela, Zimbabwe, and South Korea. Generational equity is defined as fairness over time. The issue of permanent radioactive waste disposal is a current issue that has implications for future generations. Three strategies are important in assuring generational equity: the maintenance of natural and cultural diversity; a reduction in environmental degradation; and the provision of equal access to resources. Preservation of parkland is a positive strategy and lack of access to health services and reproductive health care is a negative strategy. Procedural equity is defined as the extent to which regulations are applied fairly. The example is given of higher fines for dumping waste in "nice White communities" compared to minority ones. Environmental law regulating hazardous waste exports has been minimally effective. Women and children are affected by particulate pollution and environmental toxins (lead and pesticides) in the air and water of urban areas and by a composite of poverty, development, and urbanization.     

Integrated Hazards Mapping Tool

The Disaster Mitigation Act of 2000 formally establishes a national program for pre‐disaster mitigation. As part of the mitigation planning effort, state and local governments are required to perform assessments of hazards vulnerability, including the development of multi‐hazard maps. However, the number of communities possessing the technology, expertise, and time to create multi‐hazard vulnerability maps is limited due to technical and resource constraints. The use of Internet mapping technology has the potential to overcome these hurdles because it does not require users to possess a high level of GIS expertise or costly software, and it standardizes the vulnerability mapping approach. This article describes the Integrated Hazards Assessment Tool, a web‐based multi‐hazard vulnerability mapping application for local and state hazard mitigation practitioners in the state of South Carolina. The initial findings suggest the application holds strong potential as a viable decision support tool for hazard mitigation planning.     

Analytical intercomparison results from the 1990 Intergovernmental Oceanographic Commission open-ocean baseline survey for trace metals: Atlantic Ocean

“Dissolved” (< 0.4 μm filtered) and “total dissolvable” (unfiltered) trace element samples were collected using “clean” sampling techniques from four vertical profiles in the eastern Atlantic Ocean on the first IOC Trace Metals Baseline expedition. The analytical results obtained by 9 participating laboratories for Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, and Se on samples from station 4 in the northeast Atlantic have been evaluated with respect to accuracy and precision (intercomparability). The data variability among the reporting laboratories was expressed as 2 × SD for a given element and depth, and was comparable to the 95% confidence interval reported for the NASS seawater reference standards (representing analytical variability only). The discrepancies between reporting laboratories appear to be due to inaccuracies in standardization (analytical calibration), blank correction, and/or extraction efficiency corrections.Several of the sampling bottles used at this station were not adequately pre-cleaned (anomalous Pb results). The sample filtration process did not appear to have been a source of contamination for either dissolved or particulate trace elements. The trace metal profiles agree in general with previously reported profiles from the Atlantic Ocean. We conclude that the sampling and analytical methods we have employed for this effort, while still in need of improvement, are sufficient for obtaining accurate concentration data on most trace metals in the major water masses of the oceans, and to enable some evaluation of the biogeochemical cycling of the metals.     

The importance of physical and biogenic structure to juvenile fishes on the shallow inner continental shelf

Fish-habitat relationships on the shallow inner continental shelf were quantified with video sled and metered beam trawl on Fenwick and Weaver shoals offshore of Maryland and Delaware, U.S. These areas provide megascale physical relief and habitat complexity, but for juvenile fishes, mesoscale and microscale habitat is very important particularly as refuge from predation. At these smaller scales, much of the relief on the inner continental shelf is contributed by bedforms or sand waves and biogenic structures such as tubes, shell beds, or pits. A quantitative association for juvenile fishes between and within benthic habitats was found and related primarily to bedform size and amount of biogenic structure. The incidence of fishes was about four-times higher for large bedforms (> 30 cm wavelength and about 10 cm crest height) relative to smaller bedforms (<30 cm wavelength and about 5 cm crest height). For biogenic structure, going from high patch-mat tube densities to lower densities or no biogenic structure increased fish incidence by 5.4 and 3.3 times, respectively. The significant relationships of fishes with bedform size and density of biogenic structure indicated that seemingly small differences in physical structure of a habitat can make the difference between unacceptable and essential habitat for juvenile fishes. Proximity of complex and simple habitats was important in the diel use of habitat and in balancing pressure of refuge from predation provided by complex habitats with foraging for increased resources available in simpler habitats. During the day, spatially complex habitats comprised ofDiopatra andAsabellides tube mats had about twice as many fishes relative to bare sandy habitats (8.3–9.9 versus 4.0–4.1 fishes 100 m⁻², respectively). At night, the pattern was reversed with more fishes present in the bare sandy habitats (12.4–13.5 versus 5.6–8.7 fishes 100 m⁻²). Some fish, such asAmmodytes spp., were very habitat specific and occurred only on dynamic coarser sands near the top of the shoals. Others, such asUrophycis regia, showed less habitat preference and occurred in all habitats during both day and night. Combining the effects of physical relief and biogenics, the habitat with the highest incidence of fishes had large bedforms with some biogenic structure. More emphasis needs to be placed on quantifying the relationship between fishes and their habitats for the fisheries management concept of essential fish habitat to develop into an effective tool on the inner continental shelf. The juvenile life history stages need to be emphasized because fish-habitat interactions are the strongest for these stages and may be the most ecologically important.