Regional source identification using Lagrangian stochastic particle dispersion and HYSPLIT backward-trajectory models

The main objective of this study was to investigate the capabilities of the receptor-oriented inverse mode Lagrangian Stochastic Particle Dispersion Model (LSPDM) with the 12-km resolution Mesoscale Model 5 (MM5) wind field input for the assessment of source identification from seven regions impacting two receptors located in the eastern United States. The LSPDM analysis was compared with a standard version of the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) single-particle backward-trajectory analysis using inputs from MM5 and the Eta Data Assimilation System (EDAS) with horizontal grid resolutions of 12 and 80 km, respectively. The analysis included four 7-day summertime events in 2002; residence times in the modeling domain were computed from the inverse LSPDM runs and HYPSLIT-simulated backward trajectories started from receptor-source heights of 100, 500, 1000, 1500, and 3000 m. Statistics were derived using normalized values of LSPDM- and HYSPLIT-predicted residence times versus Community Multiscale Air Quality model-predicted sulfate concentrations used as baseline information. From 40 cases considered, the LSPDM identified first- and second-ranked emission region influences in 37 cases, whereas HYSPLIT-MM5 (HYSPLIT-EDAS) identified the sources in 21 (16) cases. The LSPDM produced a higher overall correlation coefficient (0.89) compared with HYSPLIT (0.55-0.62). The improvement of using the LSPDM is also seen in the overall normalized root mean square error values of 0.17 for LSPDM compared with 0.30-0.32 for HYSPLIT. The HYSPLIT backward trajectories generally tend to underestimate near-receptor sources because of a lack of stochastic dispersion of the backward trajectories and to overestimate distant sources because of a lack of treatment of dispersion. Additionally, the HYSPLIT backward trajectories showed a lack of consistency in the results obtained from different single vertical levels for starting the backward trajectories. To alleviate problems due to selection of a backward-trajectory starting level within a large complex set of 3-dimensional winds, turbulence, and dispersion, results were averaged from all heights, which yielded uniform improvement against all individual cases.     

Perceptions of disorder: Contributions of neighborhood characteristics to subjective perceptions of disorder

Theoretical explanations and empirical evidence of how disorder is perceived and its relation to independently observed measures of disorder are rare. In recent work, Sampson and Raudenbush [2004. Seeing disorder: Neighborhood stigma and the social construction of “Broken Windows”. Social Psychology Quarterly, 67(4), 319–342] investigated how individuals form perceptions of disorder and found that perceptions of disorder in Chicago neighborhoods are shaped not only by observable conditions of disorder, but also by neighborhoods’ racial and socioeconomic composition. In this paper, we investigate the bases for perceiving disorder with data from Baltimore using a methodology similar to that used by Sampson and Raudenbush (2004). Using surveys, systematic social observations, census data, and police records to investigate variations in individual perceptions of disorder at the individual and neighborhood levels, this study, consistent with the literature, finds that visual cues of disorder are not unambiguous and that perceptions of disorder are based not only on neighborhood observed disorder but also on individual characteristics of residents and neighborhood social structure. Additionally, our findings indicate that neighborhood poverty and not neighborhood racial composition affects perceptions of disorder in Baltimore. The fact that these findings are in contrast to the findings in Chicago suggests that the influence of racial segregation on perception of disorder is imbedded in the larger historical context.     

Ecological changes and local knowledge in a giant honey bee (<Emphasis Type="Italic">Apis dorsata</Emphasis> F.) hunting community in Palawan,Philippines

One of the traditional livelihood practices of indigenous Tagbanuas in Palawan, Philippines is wild honey hunting and gathering from the giant honey bee (Apis dorsata F.). In order to analyze the linkages of the social and ecological systems involved in this indigenous practice, we conducted spatial, quantitative, and qualitative analyses on field data gathered through mapping of global positioning system coordinates, community surveys, and key informant interviews. We found that only 24% of the 251 local community members surveyed could correctly identify the giant honey bee. Inferential statistics showed that a lower level of formal education strongly correlates with correct identification of the giant honey bee. Spatial analysis revealed that mean NDVI of sampled nesting tree areas has dropped from 0.61 in the year 1988 to 0.41 in 2015. However, those who correctly identified the giant honey bee lived in areas with high vegetation cover. Decreasing vegetation cover limits the presence of wild honey bees and this may also be limiting direct experience of the community with wild honey bees. However, with causality yet to be established, we recommend conducting further studies to concretely model feedbacks between ecological changes and local knowledge.     

Trends and applications of multi-criteria decision analysis: use in government agencies

Government agencies are responsible for making complex, high-stake decisions, which require them to balance political, technical, and economic considerations. Pressure from stakeholders and administrative requirements necessitate a traceable and transparent method for decision making. Multi-criteria decision analysis (MCDA) methods are available to decision makers to facilitate systematic treatment of the information and factors necessary to make informed and effective decisions in complex circumstances. A survey of gray and academic literature was conducted to gauge the level of application and awareness of MCDA methods by US government agencies and determine if the tools’ benefits are being realized. Results show an increase in awareness and consideration of MCDA from 2000 to the present, and that agencies are especially considering and using tools to engage with stakeholders. Government agencies would benefit from extending the application of MCDA to strategic planning and congressional engagement, as well as by standardizing MCDA use to better enable inter-agency collaboration and communication.     

Critical Review of Exposure and Effects: Implications for Setting Regulatory Health Criteria for Ingested Copper

Environmental Management - Decades of study indicate that copper oral exposures are typically not a human health concern. Ingesting high levels of soluble copper salts can cause acute...     

Compatibility of hydroxypropyl-beta-cyclodextrin with algal toxicity bioassays

Numerous reports have indicated that hydrophobic organic compound bioaccessibility in sediment and soil can be determined by extraction using aqueous hydroxypropyl-β-cyclodextrin (HPCD) solutions. This study establishes the compatibility of HPCD with Selenastrum capricornutum and assesses whether its presence influences the toxicity of reference toxicants. Algal growth inhibition (72 h) showed no significant (P > 0.05) difference at HPCD concentrations up to and including 20 mM. HPCD presence did not influence the toxicity of the inorganic reference toxicant (ZnSO₄), with IC50 values of 0.82 μM and 0.85 μM, in the presence and absence of HPCD (20 mM), respectively. However, HPCD presence (20 mM) reduced the toxicity of 2,4-dichlorophenol and the herbicides diuron and isoproturon. These reductions were attributed to inclusion complex formation between the toxicants and the HPCD cavity. Liberation of complexed toxicants, by sample manipulation prior to toxicity assessment, is proposed to provide a sensitive, high throughput, bioassay that reflects compound bioaccessibility.     

Estimating the spatial scale of herbicide and soil interactions by nested sampling, hierarchical analysis of variance and residual maximum likelihood

An unbalanced nested sampling design was used to investigate the spatial scale of soil and herbicide interactions at the field scale. A hierarchical analysis of variance based on residual maximum likelihood (REML) was used to analyse the data and provide a first estimate of the variogram. Soil samples were taken at 108 locations at a range of separating distances in a 9 ha field to explore small and medium scale spatial variation. Soil organic matter content, pH, particle size distribution, microbial biomass and the degradation and sorption of the herbicide, isoproturon, were determined for each soil sample. A large proportion of the spatial variation in isoproturon degradation and sorption occurred at sampling intervals less than 60 m, however, the sampling design did not resolve the variation present at scales greater than this. A sampling interval of 20-25 m should ensure that the main spatial structures are identified for isoproturon degradation rate and sorption without too great a loss of information in this field.     

Impact of Cathode Conditions on Coupled Electrochemical Treatment of Nitrate Brine Concentrates

Simulated concentrated nitrate brine waste was treated in a two-stage electrolysis process, where reduction of nitrate in a cathodic chamber was coupled with oxidation of ammonium (produced in the previous stage) in an anodic chamber. The influence of operating conditions such as applied potential, electrolyte composition, and initial concentration on conversion of nitrate to ammonium in the cathodic chamber was investigated. The effects of chloride and current density on the two-stage treatment process were also examined. More negative potential at the cathode (?2.0 vs. ?1.7 and ?1.5 V) and higher current density (33 vs. 22 and 13.9 mA/cm²) favored ammonium as the product of nitrate reduction at a copper cathode and increased the overall amount of nitrate conversion. Faster reduction was seen when nitrate concentration was lower (0.01 vs. 0.02 N), but total mass conversion of nitrate in the same time period was higher for 0.02 N. The reduction of nitrate was not sensitive to sulfate or chloride concentration in the ranges studied (0–2 and 1–1.5 mg/L, respectively), but the oxidation of ammonium was noticeably higher when chloride was present. Only small amounts of ammonium and nitrate remained in the second-stage effluent after coupled treatment.     

Effects of fifteen PBDE metabolites, DE71, DE79 and TBBPA on steroidogenesis in the H295R cell line

Polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol A (TBBPA) are brominated flame retardants that are produced in large quantities and are commonly used in construction materials, textiles, and as polymers in electronic equipment. Environmental and human levels of PBDEs have been increasing in the past 30 years, but the toxicity of PBDEs is not fully understood. Studies on their effects are relatively limited, and show that PBDEs are neurotoxins and potential endocrine disrupters. Hydroxylated (OH) and methoxylated (MeO) PBDEs have also been reported in the adipose tissue, blood and milk of wild animals and humans. In the present study, 15 PBDE metabolites, two BDE mixtures (DE71 and DE79), and TBBPA were studied individually to determine their effects on ten steroidogenic genes, aromatase activity, and concentrations of two steroid hormones (testosterone and 17beta-estradiol) in the H295R human adrenocortical carcinoma cell line. Exposure to 0.05 microM 2'-OH-BDE-68 significantly induced the expression of CYP11A, CYP11B2, CYP17, CYP21, 3betaHSD2, 17betaHSD1, and 17betaHSD4, and the expression of StAR was induced by 6-OH-BDE-90 at the three exposure concentrations. Exposure to DE71 and DE79 resulted in dose-dependent trend towards induction, but these effects were not significant. Exposure to 0.5 microM 2-OH-BDE-123 and 2-MeO-BDE-123 resulted in significantly greater aromatase activity. However, none of the compounds affected sex hormone production at the concentrations tested. Generally, OH-BDEs had a much stronger ability to affect steroidogenic gene expression than MeO-BDEs.