Soil arsenic surveys of New Orleans: localized hazards in children’s play areas

Arsenic (As) ranks first on the 2005 and 2007 hazardous substances priority lists compiled for the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). This study describes two New Orleans soil As surveys: (1) a survey of composite soil samples from 286 census tracts and (2) a field survey of soil As at 38 play areas associated with the presence of chromated-copper-arsenate (CCA)-treated wood on residential and public properties. The survey of metropolitan New Orleans soils revealed a median As content of 1.5 mg/kg (range <0.2–16.4) and no distinctive differences between the soils of the city core and outlying areas. Play area accessible soils associated with CCA-treated wood (N = 32) had a median As of 57 mg/kg and 78% of the samples were ≥12 mg/kg, the Louisiana soil As standard. The field survey of play areas for CCA-treated wood (N = 132 samples at 38 sites) was conducted with a portable energy-dispersive X-ray fluorescence (XRF) analyzer. Seventy-five of 132 wood samples (56.8%) were deemed CCA-treated wood. Of the 38 play areas surveyed, 14 (36.8%) had CCA-treated wood. A significant association (Fisher’s exact p-value = 0.348 × 10⁻⁶) was found between CCA-treated wood and soil As (N = 75). At one elementary school CCA-treated woodchips (As range 813–1,654 mg As/kg) covered the playgrounds. The situation in New Orleans probably exists in play areas across the nation. These findings support a precautionary program for testing soils and wood for hazardous substances at all play areas intended for children.     

Geospatial analysis of vulnerable beach-foredune systems from decadal time series of lidar data

Time series of lidar data, acquired over the past decade along the North American East Coast, provide opportunities to gain new insights into 3D evolution of barrier islands and their beach and dune systems. GIS-based per grid cell statistics and map algebra was applied to time series of Digital Surface Models representing two sections of North Carolina barrier islands to quantify elevation change trends, map dynamic and stable locations, identify new and lost buildings, measure relative volume evolution in the beach and foredune systems and analyze shoreline dynamics. Results show a relatively small stable core in both study areas, with beaches and the ocean side of the dunes exhibiting systematic high rates of elevation loss while areas landward from the dunes increase slightly in elevation. Significant number of new homes have been built at locations with very small core surface elevation, and homes built within the shoreline dynamics band have already been lost. The raster-based methodology used in this study can be applied to perform similar analyses in other coastal areas where time series of lidar data are available.     

Bioenhancement of NAPL pool dissolution: experimental evaluation

Experiments were conducted to quantify nonaqueous phase liquid (NAPL) pool dissolution and its enhancement by in situ biodegradation. The experiments were performed using square cross-section, glass-bead packed column reactors with a small pool of a toluene-in-dodecane mixture (toluene mole fraction, X(tol) approximately 0.02 or 0.09). Experimental quasi-steady-state toluene dissolution fluxes were determined using a 14C-carbon mass-balance approach during water flushing with and without biodegradation. The experiments demonstrated a statistically significant bioenhancement of the toluene dissolution flux of up to roughly twofold at average pore water velocities of approximately 0.1 and 1 m/day when the toluene mole fraction was low ( approximately 0.02); however, little or no bioenhancement was observed with the higher mole fraction ( approximately 0.09). Although it cannot be determined conclusively, the weight of evidence based on biomass measurements and model analyses suggests that the reduced bioenhancement for the high mole fraction was due to higher dissolved toluene concentrations, which may have caused toxicity effects. Importantly, even though NAPL dissolution was not bioenhanced in every case, the biodegradation reduced toluene concentrations to low levels in the reactor effluents.     

SAGE: A NEW PARTICIPANT-VALUE METHOD FOR ENVIRONMENTAL ASSESSMENT1

SAGE, a proposed method for environmental assessment, focuses on eliciting and incorporating value weights in multiple-objective decision making. In this method, the value weights are inferred from the tradeoffs that people make in choices about alternatives. These weights are applied to scaled scores for accounts based on measurable attributes of each objective. In order to indicate the political ramifications of decisions and to facilitate sensitivity analysis, the values held by various groups are presented in matrix from arrayed by group affiliation or by judgment types that share common values. Results of a trial application of SAGE to a land use/watershed management problem in a growing urban area are presented.     

Natural resource economics: Relevance in planning and management

This article provides an overview of natural resource economics. It begins with a summary of historical and current views on resource scarcity. It then discusses economic models for optimal management of non-renewable and renewable resources at the micro and macro levels and evaluates their usefulness in planning, management and policy making.     

Mechanical separation-oriented characterization of electronic scrap

The ever-increasing amount of electronic scrap and the steadily-decreasing contents of the precious metals used in electronics, as well as the ever-growing environmental awareness, challenges such conventional precious-metal-oriented recycling techniques as pyrometallurgy. Separation and beneficiation of various materials encountered in electronic scrap might provide a correct solution ahead. In this context, mechanical separation-oriented characterization of electronic scrap was conducted in an attempt to evaluate the amenability of mechanical separation processes. Liberation degrees of various metals from the non-metals, which are crucial for mechanical separation, were analyzed by means of a grain counting approach. It is found that the metallic particles below 2 mm achieve almost complete liberation. Particle shapes were also quantified through an image processing system. The results obtained show that the shapes of the particles, as a result of shredding, turn out to be heterogeneous, thereby complicating mechanical separation processes. In addition, separability of various materials was ascertained by a sink–float analysis. It has been shown that density-based separation techniques shall be viable in separating metals from plastics, light plastics (ABS, PS and PVC, etc.) from glass fiber reinforced resins and aluminum from heavy metals. Specifically, a high quality copper concentrate can be expected by density-based separation techniques. Moreover, FT-IR spectra of plastics pieces from the light fractions after the sink–float testing show that PC scrap primarily contains ABS, PS and PVC plastics with the density range of +1.0–1.5 g/cm³, whereas PCB scrap mainly contains glass fiber reinforced epoxy resins plastics with the density range of +1.5–2.0 g/cm³.     

The effectiveness of home-study driver education compared to classroom instruction: the impact on student knowledge and attitudes

PROBLEM: Home-study driver education programs exist in several states, but none have been scientifically evaluated to determine if such courses are as effective as classroom courses for teaching driver education. METHOD: Over 1,300 students were randomly assigned to classroom instruction, or CD ROM, workbook, or Internet/workbook home-study courses and compared on proctored exit examination knowledge and attitude scores, and written knowledge test outcomes. RESULTS: Few differences were found on exit examination knowledge and attitude scores, but they tended to favor the CD and Internet/workbook home-study courses over the classroom or workbook courses. Differences favoring the classroom on written knowledge test outcomes likely reflect a bias in classroom courses toward teaching test-specific material. DISCUSSION: The findings present no compelling evidence that home-study courses are less effective than classroom courses for teaching driver education. IMPACT ON INDUSTRY: The findings could result in more widespread use of home-study courses. Also, the use of low-cost home-study courses as the first course of a two-stage driver education and training system could make integrating such programs with graduated driver licensing more feasible and acceptable to the public.     

Low Levels of Sodium and Potassium in the Water from Wetlands in Minnesota that Contained Malformed Frogs Affect the Rate of Xenopus Development

Water samples were collected between 1999 and 2000 from wetlands in Minnesota that contained malformed frogs. The water samples were analyzed for 14 minerals/ions and screened for the presence of biologically active compounds using Xenopus laevis. Results indicated that water from two sites, CWB and ROI2, induced severe retardation with embryo lengths reduced 20% after 96 hr of development. The developmental delay observed with water from ROI2 was alleviated by supplementation with sodium, while both sodium and potassium alleviated the developmental delay observed with water whose mineral content mimicked that of CWB. Seasonal fluctuations in the sodium and potassium content at ROI2 and NEY correlated with changes in the rates of Xenopus development. Xenopus embryos reared on water from ROI2 for 120 hr displayed gut malformations not present in embryos reared on a synthetic media designed to mimic the mineral content of the water from ROI2. Embryos reared on water from ROI2 supplemented with minerals at levels comparable to that routinely employed in the rearing of Xenopus were neither retarded nor malformed. It is proposed that climate driven hydrology may influence the mineral composition at selected wetlands and delay development which may alter window(s) of susceptibility towards biologically active agents and the occurrence of malformed frogs.     

Radiocarbon behaviour in seawater and the brown algae Fucus serratus in the vicinity of the COGEMA La Hague spent fuel reprocessing plant (Goury)--France

Extensive studies of the radiocarbon (14C) distribution and transfer in the marine environment of the North-Cotentin peninsula and along the English Channel have been carried out. The main aims of these studies have been to estimate the spatial and temporal variation of the 14C concentration in seawater and to calculate 14C concentration factors for some biological species. Such information will be helpful in order to calculate precisely radiation doses to humans. First results obtained in the vicinity of the COGEMA La Hague nuclear plant (Goury) indicate a 14C labelling of the dissolved inorganic carbon (DIC) in seawater (8.0-26.2 Bq.m(-3)) and a tight relationship between the 14C in the liquid releases from the plant and the 14C concentrations in DIC. The particulate organic carbon (POC) is also labelled. The concentration factor calculations for the brown algae (Fucus serratus) sampled from Goury, and also along the English Channel, give 14C values around 3000 Bq.kg(-1) fresh weight / Bq.L(-1).     

Direct measurement of octanol-water partition coefficients of some environmentally relevant brominated diphenyl ether congeners

Octanol-water partition coefficients (K(OW)) of nine environmentally relevant brominated diphenyl ether (BDE) congeners present in two technical mixtures were directly measured using a slow-stir technique. LogK(OW) values of tri- to heptabrominated BDE congeners ranged from 5.74 to 8.27, and were related to bromine content by the equation logK(OW)=0.621(#Br)+4.12(R(2)=0.970). The directly determined K(OW) values were generally lower than those calculated using fragment constant methods, particularly at higher levels of bromine substitution. The quasi-experimental approach of using fragment constants to modify a "backbone" compound of known K(OW) was much more successful than using the fragment constants to "build" the entire molecule. The tri- and tetrabrominated congeners are in the range of optimum bioaccumulation potential.