Geologic vs. geographic constraints on cement resources

This study evaluates the importance of geologic and geographic factors in constraining the location of limestone mining operations for the production of cement in the Great Lakes region of the United States. Cities and their infrastructure require abundant cement, which is manufactured from limestone and other quarry products, but expansion of cities limits the locations of these operations. Possible locations of limestone and cement operations are controlled by geologic factors including distribution and mineralogy of geologic formations as well as depth of overburden, and geographic factors including location of wetlands, cities, and other surface features that preclude development of quarries and manufacturing operations. Overlay analysis was used to evaluate the importance of these factors. Results show that, although limestone underlies about a third of the region, almost 50 percent of this limestone is unavailable for quarrying due to coverage by the built environment, protected natural areas, or excessive overburden thickness. When characteristics such as limestone quality are also accounted for, accessible resources shrink to as little as 2 percent of the total land area. Although the remaining 2 percent of land area may supply local needs for some years, geologic factors clearly must be included in long-term regional land use planning.     

Comparative study of hotplate wet digestion methods for the determination of mercury in biosolids

The re-use of biosolids is becoming increasingly popular for land applications. However, biosolids may contain elevated levels of metals and metalloids (including mercury) relative to background environmental concentrations. Consequently, reliable mercury analysis is important to allow classification of biosolids and to determine appropriate options for beneficial uses. This paper reports on a comparative study of 12 hotplate wet digestion methods for their suitability for the determination of mercury in biosolids. The methods were applied to mercury biosolids samples from four localities of two different sewage treatment plants in the State of Victoria, Australia. Samples were also spiked with methylmercury chloride and mercury sulphide to evaluate the Hg recovery in each hotplate digestion method. Aqua regia (HCl:HNO(3)=3:1), reverse aqua regia (HCl:HNO(3)=1:3), nitric, hydrochloric, sulphuric acid and their combinations with or without hydrogen peroxide were studied as wet digestion solutions. The method providing the best mercury recoveries was optimized. Under optimal conditions the corresponding analytical procedure consisted of 1h pre-digestion of 0.4 g biosolids sample with 10 ml reverse aqua regia with temperature increasing to 110 degrees C and 3h digestion at this temperature. In the last 10 min of the digestion step, 2 ml hydrogen peroxide were added to ensure complete decomposition of all mercury containing compounds. After filtering and dilution with deionised water (1:10), the concentration of mercury was determined by cold vapour atomic absorption spectrometry. It is expected, that the wet acid digestion method developed in this study will be also applicable to biosolids from other sewage treatment plants and to other types of solid mercury samples with elevated levels of organic matter.     

Membrane introduction/laser photoionization time-of-flight mass spectrometry

Two-photon resonance enhanced multiphoton ionization (REMPI) has been shown to be a unique ionization method for mass spectrometry, exhibiting both high sensitivity and chemical selectivity. Because REMPI is a gas-phase method, its applications have been limited either to direct analysis of vapor phase samples, or in conjunction with an initial laser desorption or other vaporization step. We describe here for the first time a combination of membrane introduction mass spectrometry (MIMS) and REMPI with time-of-flight mass spectrometry (TOF-MS), which allows for the direct analysis of trace amounts of organic compounds in water samples. The objective of our research was the detection of very low levels of aromatic contaminants, particularly benzene, toluene, and xylene (BTX), in aqueous solutions without interference due to the water. We have measured limits of detection (LOD) for selected aromatics in water below 1 part-per-trillion with an averaging time of less than 10 s using a continuous sample flow.     

Comparison of TNT removal from seawater by three marine macroalgae

Axenic plantlets derived from three species of marine macroalgae, the temperate green alga Acrosiphonia coalita, the temperate red alga Porphyra yezoensis, and the tropical red alga Portieria hornemannii, all possessed a similar metabolic route to remove the explosive compound 2,4,6-trinitrotolune (TNT) from seawater. At a biomass density of 1.2 g l(-1) and initial TNT concentrations of 10 mg l(-1) or less, TNT removal from seawater was 100% within 72 h for P. hornemannii and P. yezoensis. Specific rate constants for TNT uptake were 0.016-0.018 l g(-1)FWh(-1) for A. coalita filaments, 0.047-0.062 l g(-1)FW h(-1) for P. yezoensis blades, and 0.037-0.049 l g(-1)FW h(-1) for P. hornemannii microplantlets. Only trace amounts of TNT were found within the biomass. All species reduced TNT to 2-amino-4,6-dinitrotoluene and 4-amino-2,6-dintrotoluene, but these products never accounted for more than 20% of the initial TNT.     

Screening Technology Trains for DNAPL Remediation

The Department of Energy (DOE) is conducting a Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) mandated Remedial Investigation/Feasibility Study for a site contaminated with Dense Non-Aqueous Phase Liquid (DNAPL) pollutants. Three key efforts were a hydrogeological modeling approach, the generation of feasible sequences of technologies, and the screening of alternative technologies. This research uses a decision analysis process to provide a quantitative assessment of the candidate technologies. Decision analysis modeling was used to gain insight into each sequence of technologies. Sensitivity analysis was also conducted to assess the impact of key assumptions. The results provided the DOE with an objective and traceable rationale for screening and reducing all of the potential technology combinations to 58 technology combinations and a method for identifying the top scoring combinations. The approach has wide applicability to similar CERCLA remediation efforts.     

Tradition without social learning: scent-mark-based communal roost formation in a Neotropical harvestman (Prionostemma sp.)

Most models of habitat selection assume that individual animals choose and either reuse or abandon sites based on a constant reassessment of site quality. When survival is a function of the presence of conspecifics, however, the benefits of returning to traditional sites may override resource assessment. Many animals form roosting aggregations at what appear to be traditional sites. At our study site in Nicaragua, the harvestman Prionostemma sp. forms diurnal roosting aggregations on a small subset of the available spiny palm trees. With respect to physical characteristics and microclimate, the spiny palms used by the harvestmen resembled a random sample of those available, yet the same subset of trees was used in two different years (2001, 2003). This suggests that the location of aggregation sites is traditional, not a product of habitat limitation. Individual harvestmen were not faithful to particular roost sites, however, which raises the question of how the tradition could be maintained over time. In this paper, we present evidence, derived from a series of small-scale field experiments, that the harvestmen mark roosting sites chemically and enter marked sites preferentially when searching for places to roost. We also show that the harvestmen are sensitive to changes in site quality (the presence of spines) but will continue to use degraded traditional sites when no intact spiny palms are nearby. This system provides an example of how animal traditions could be maintained over multiple generations without learning. Site-labeling can be viewed as an external form of social memory.     

Adapting the bioblitz to meet conservation needs

When conservation strategies require new, field‐based information, practitioners must find the best ways to rapidly deliver high‐quality survey data. To address this challenge, several rapid‐assessment approaches have been developed since the early 1990s. These typically involve large areas, take many months to complete, and are not appropriate when conservation‐relevant survey data are urgently needed for a specific locale. In contrast, bioblitzes are designed for quick collection of site‐specific survey data. Although bioblitzes are commonly used to achieve educational or public‐engagement goals, conservation practitioners are increasingly using a modified bioblitz approach to generate conservation‐relevant data while simultaneously enhancing research capacity and building working partnerships focused on conservation concerns. We term these modified events expert bioblitzes. Several expert bioblitzes have taken place on lands of conservation concern in Southern California and have involved collaborative efforts of government agencies, nonprofit organizations, botanic gardens, museums, and universities. The results of expert bioblitzes directly informed on‐the‐ground conservation and decision‐making; increased capacity for rapid deployment of expert bioblitzes in the future; and fostered collaboration and communication among taxonomically and institutionally diverse experts. As research and conservation funding becomes increasingly scarce, expert bioblitzes can play an increasingly important role in biodiversity conservation.     

Associations of Decadal to Multidecadal Sea‐Surface Temperature Variability with Upper Colorado River Flow1

Abstract: The relations of decadal to multidecadal (D2M) variability in global sea‐surface temperatures (SSTs) with D2M variability in the flow of the Upper Colorado River Basin (UCRB) are examined for the years 1906‐2003. Results indicate that D2M variability of SSTs in the North Atlantic, North Pacific, tropical Pacific, and Indian Oceans is associated with D2M variability of the UCRB. A principal components analysis (with varimax rotation) of detrended and 11‐year smoothed global SSTs indicates that the two leading rotated principal components (RPCs) explain 56% of the variability in the transformed SST data. The first RPC (RPC1) strongly reflects variability associated with the Atlantic Multidecadal Oscillation and the second RPC (RPC2) represents variability of the Pacific Decadal Oscillation, the tropical Pacific Ocean, and Indian Ocean SSTs. Results indicate that SSTs in the North Atlantic Ocean (RPC1) explain as much of the D2M variability in global SSTs as does the combination of Indian and Pacific Ocean variability (RPC2). These results suggest that SSTs in all of the oceans have some relation with flow of the UCRB, but the North Atlantic may have the strongest and most consistent association on D2M time scales. Hydroclimatic persistence on these time scales introduces significant nonstationarity in mean annual streamflow, with critical implications for UCRB water resource management.     

An evaluation of the effectiveness of a baby walker safety standard to prevent stair-fall injuries

PROBLEM: During the early 1990s the number of baby walker injuries treated in U.S. hospital emergency departments averaged almost 25,000 annually; about 80% resulted from falls down stairs. After initiating a regulatory proceeding in 1994, the U.S. Consumer Product Safety Commission staff worked with industry to develop requirements to address the stair-fall hazard. This study evaluates the effectiveness of the stair-fall requirements, which became effective in 1997 as part of a revised voluntary standard. METHOD: Annual baby walker emergency department injury rates were constructed for the 1981-2002 study period. A multivariate negative binomial regression model was used to estimate the effectiveness of the stair-fall requirements in reducing the injury rate. RESULTS: The stair-fall requirements reduced the emergency department injury rate by an estimated 63% (95% CI, 52% to 71%). IMPACT ON INDUSTRY: Given the substantial reduction in walker injuries, and the high level of industry conformance with the stair-fall requirements, the Commission terminated its regulatory proceeding in May, 2002. The success of the baby walker project highlights the ability of government and industry to work together cooperatively to develop effective safety improvements for consumer products.     

Macro kinetic studies for photocatalytic degradation of benzoic acid in immobilized systems

Semiconductor photocatalytic process has been studied extensively in recent years due to its intriguing advantages in environmental remediation. In this study, a two-phase swirl-flow monolithic-type reactor is used to study the kinetics of photocatalytic degradation of benzoic acid in immobilized systems. Transport contributions into the observed degradation rates were determined when catalyst is immobilized. Intrinsic kinetic rate constants and its dependence on light intensity and catalyst layer thickness, values of adsorption equilibrium constant, internal as well as external mass transfer parameters were determined. The simultaneous effect of catalyst loading and light intensity and optimum catalyst layer thickness were also determined experimentally. Reaction rate constants and overall observed degradation rates were compared with slurry systems.