A comparison of speciated atmospheric mercury at an urban center and an upwind rural location

Gaseous elemental mercury (GEM), particulate mercury (PHg) and reactive gaseous mercury (RGM) were measured every other hour at a rural location in south central Wisconsin (Devil's Lake State Park, WI, USA) between April 2003 and March 2004, and at a predominantly downwind urban site in southeastern Wisconsin (Milwaukee, WI, USA) between June 2004 and May 2005. Annual averages of GEM, PHg, and RGM at the urban site were statistically higher than those measured at the rural site. Pollution roses of GEM and reactive mercury (RM; sum of PHg and RGM) at the rural and urban sites revealed the influences of point source emissions in surrounding counties that were consistent with the US EPA 1999 National Emission Inventory and the 2003-2005 US EPA Toxics Release Inventory. Source-receptor relationships at both sites were studied by quantifying the impacts of point sources on mercury concentrations. Time series of GEM, PHg, and RGM concentrations were sorted into two categories; time periods dominated by impacts from point sources, and time periods dominated by mercury from non-point sources. The analysis revealed average point source contributions to GEM, PHg, and RGM concentration measurements to be significant over the year long studies. At the rural site, contributions to annual average concentrations were: GEM (2%; 0.04 ng m(-3)); and, RM (48%; 5.7 pg m(-3)). At the urban site, contributions to annual average concentrations were: GEM (33%; 0.81 ng m(-3)); and, RM (64%; 13.8 pg m(-3)).     

Utilization of Waste Lignin and Hydrolysate From Chromium Tanned Waste in Blends of Hot-Melt Extruded PVA-Starch

The demand for biodegradable plastic material is increasing worldwide. However, the cost remains high in comparison with common forms of plastic. Requirements comprise low cost, good UV-stability and mechanical properties, as well as solubility and water uptake lead to the preparation of multi-component polymer blends based on polyvinyl alcohol and starch in combination with waste products that are hard to utilize—waste lignin and hydrolysate extracted from chromium tanned waste. Surprisingly the addition of such waste products into PVA gives rise to blends with better biodegradability than commercial PVA in an aquatic aerobic environment with non-adapted activated sludge. These blends also exhibited greater solubility in the water and UV stability than commercial PVA. Tests on the processing properties of the blends (melt flow index, tensile strength and elongation at break of the films) as well as their mechanical properties showed that materials based on these blends might be applied in agriculture (for example as the systems for controlled-release pesticide or fertilizer) and, somewhat, in the packaging sector.     

COMPARISON OF STOCHASTIC AND DETERMINISTIC DYNAMIC PROGRAMMING FOR RESERVOIR OPERATING RULE GENERATION1

ABSTRACT: Two dynamic programming models — one deterministic and one stochastic — that may be used to generate reservoir operating rules are compared. The deterministic model (DPR) consists of an algorithm that cycles through three components: a dynamic program, a regression analysis, and a simulation. In this model, the correlation between the general operating rules, defined by the regression analysis and evaluated in the simulation, and the optimal deterministic operation defined by the dynamic program is increased through an iterative process. The stochastic dynamic program (SDP) describes streamflows with a discrete lag-one Markov process. To test the usefulness of both models in generating reservoir operating rules, real-time reservoir operation simulation models are constructed for three hydrologically different sites. The rules generated by DPR and SDP are then applied in the operation simulation model and their performance is evaluated. For the test cases, the DPR generated rules are more effective in the operation of medium to very large reservoirs and the SDP generated rules are more effective for the operation of small reservoirs.     

Migrating an incident reporting system to a CCPS process safety metrics model

A major chemical company established a formal incident investigation and reporting system several years ago. The original system focused heavily on worker-related injuries, illnesses, and near-misses and was used primarily to track statistics reportable to the Occupational Safety and Health Administration (OSHA). This Occupational Injury and Illness (OII) approach has been recognized to be an ineffective tool for measuring, predicting, and preventing process safety incidents. The Center for Chemical Process Safety (CCPS) recently published guidelines on how to establish safety metrics for the measurement and reduction of process safety incidents. The process safety metrics approach relies upon leading and lagging metrics to improve organization process safety. This paper is a case study of the analysis of one organization’s incident database, which represents approximately five years of data from over a dozen facilities. The aim of this investigation was to extract useful process safety metrics from the incident investigation and reporting system, which would be pertinent to the types of process units and process functions at these facilities. This paper will discuss the approach taken to extract process incident information from an OII-based database and present the difficulties of performing an analysis on such a database. This paper provides guidance on how to migrate an existing OII-based reporting system to a program that includes process safety metrics in accordance with industry best practices.     

Prevalence of alcohol among nonfatally injured road accident casualties in two level III trauma centers in northern Ghana

Background: Alcohol use is pervasive among motorists on the road in Ghana; however, we do not know the extent to which this behavior is implicated in road accidents in this country.

Objectives: The main objective of this research was to establish the prevalence of alcohol in the blood of nonfatally injured casualties in the emergency departments (EDs) in northern Ghana.

Method: Participants were injured road traffic crash victims, namely, pedestrians, cyclists, motorcyclists, and drivers seeking treatment at an ED. The study sites were 2 level III trauma centers located in Wa and Bolgatanga. Participants were screened for alcohol followed by breath tests for positive participants using breathalyzers.

Results: Two hundred and sixty-two accident victims visited EDs, 58% of whom were in Wa. Among the victims, 41% were hospitalized and 57% experienced slight injuries. The vast majority (76%) of the casualties were motorcyclists, 13% were pedestrians, 8% were cyclists, and 2% were drivers. Casualties who had detectable alcohol in their blood were predominantly vulnerable road users. In all, 34% of participants had detectable blood alcohol concentrations (BACs) and the mean BAC for all casualties who tested positive and could give definitive BACs was 0.2265 (226 mg/dl). The prevalence of alcohol use was 53% among cyclists, 34% among motorcyclists, 21% among pedestrians, and 17% among drivers. Male casualties were more likely to test positive for alcohol than females. In addition, the prevalence of alcohol was significantly higher among injured casualties in Bolgatanga compared to Wa.

Conclusion: There was a high prevalence of alcohol use among nonfatally injured casualties in northern Ghana and injury severity increased with BAC. AUDIT screening in the hospital, alcohol consumption guideline, road safety education with an emphasis on minimizing or eliminating alcohol consumption, and enhanced enforcement of the BAC limit among motorists are recommended.     

Dry and heat stress affects H2S production of Salmonella on selective plating media

The pH of Salmonella pre-enrichment media can become acidic (pH 4.0–5.0) when feeds/ingredients are incubated for 24?h. Salmonella in feed that have been stressed by heat and desiccation exhibit different pH tolerances than non-stressed cultures. Acidic conditions can result in cell injury/death and affect biochemical pathways. In this study, eight serotypes of Salmonella were grown in sterile meat and bone meal that was subjected to desiccation and heat stress. Cultures of non-stressed and stressed isolates were subsequently exposed to acidic pH from 4.0 to 7.0 in 0.5?pH increments (3 replicates/pH increment) in citrate buffer. At 6 and 24?h, serial dilutions were plated in duplicate on XLT-4 (xylose lysine tergitol-4) agar. Four serotypes showed an impaired ability to decarboxylate lysine on XLT-4. This inability to decarboxylate lysine was dependent on isolate, stress status, and incubation time. When the isolates’ ability to decarboxylate lysine was examined using biochemical tests, cultures were found to be able to decarboxylate lysine with the exception of S. Infantis. This suggests that XLT-4 contains a biochemical stressor(s) which affects the rate of decarboxylation by these Salmonella. These results suggest that acidic conditions may influence the detection and confirmation of Salmonella in feed.     

A Method for Ensemble Wildland Fire Simulation

An ensemble simulation system that accounts for uncertainty in long-range weather conditions and two-dimensional wildland fire spread is described. Fuel moisture is expressed based on the energy release component, a US fire danger rating index, and its variation throughout the fire season is modeled using time series analysis of historical weather data. This analysis is used to characterize the seasonal trend in ERC, autocorrelation of residuals, and daily standard deviation and stochastically generate artificial time series of afternoon fuel moisture. Daily wind speed and direction are sampled stochastically from joint probabilities of historical wind speed and direction for the date range of the fire simulation period. Hundreds or thousands of fire growth simulations are then performed using the synthetic fire weather sequences. The performance of these methods is evaluated in terms of the number of ensemble member simulations, one- versus two-dimensional fire spread simulations, and comparison with results from 91 fires occurring from 2007 to 2009. Simulations were found to be in consistent agreement with observations, but trends indicate that the ensemble average of simulated fire sizes were consistently larger than actual fires whereas the farthest extent burned by fires was underestimated.     

Herbivory by the Caribbean king crab on coral patch reefs

Caribbean coral reefs are increasingly dominated by macroalgae instead of corals due to several factors, including the decline of herbivores. Yet, virtually unknown is the role of crustacean macrograzers on coral reef macroalgae. We examined the effect of grazing by the Caribbean king crab (Mithrax spinosissimus) on coral patch reef algal communities in the Florida Keys, Florida (USA), by: (1) measuring crab selectivity and consumption of macroalgae, (2) estimating crab density, and (3) comparing the effect of crab herbivory to that of fishes. Mithrax prefers fleshy macroalgae, but it also consumes relatively unpalatable calcareous algae. Per capita grazing rates by Mithrax exceed those of most herbivorous fish, but Mithrax often occurs at low densities on reefs and its foraging activities are reduced in predator-rich environments. Therefore, the effects of grazing by Mithrax tend to be localized and when at low density contribute primarily to spatial heterogeneity in coral reef macroalgal communities.     

Signals for damage control: web decorations in <Emphasis Type="Italic">Argiope keyserlingi</Emphasis> (Araneae: Araneidae)

Orb web spiders of the genus Argiope are permanently located at the hub of the orb web and are thus vulnerable to changing environmental conditions. Severe damage to the web by non-prey animals can have a significant impact on survival, through the cost of producing expensive silk and the loss of foraging opportunities. Thus, selection should favor web protection mechanisms, and the conspicuous web decorations, typical of Argiope spiders, may play a role. Decorated webs suffer less damage than undecorated webs, consistent with the view that they advertise the presence of the web to non-prey animals that may damage the web. However, whether spiders respond to web damage by increasing investment in web decorations has not been investigated. We subjected adult St. Andrew's Cross spider (Argiope keyserlingi) females to three levels of web damage and recorded their subsequent web-decorating behavior. Mild damage, similar to that caused by impacting prey, did not affect either web building or decorating behavior. However, spiders subjected to substantial web damage both reduced the size of subsequent webs and increased investment in web decoration size. These data are consistent with an advertising role of web decorations.     

A practical method for quantification of phosphorus- and glycogen-accumulating organism populations in activated sludge systems.

Enhanced biological phosphorus removal (EBPR) from wastewater relies on the enrichment of activated sludge with phosphorus-accumulating organisms (PAOs). The presence and proliferation of glycogen-accumulating organisms (GAOs), which compete for substrate with PAOs, may be detrimental for EBPR systems, leading to deterioration and, in extreme cases, failure of the process. Therefore, from both process evaluation and modeling perspectives, the estimation of PAO and GAO populations in activated sludge systems is a relevant issue. A simple method for the quantification of PAO and GAO population fractions in activated sludge systems is presented in this paper. To develop such a method, the activity observed in anaerobic batch tests executed with different PAO/GAO ratios, by mixing highly enriched PAO and GAO cultures, was studied. Strong correlations between PAO/GAO population ratios and biomass activity were observed (R2 > 0.97). This served as a basis for the proposal of a simple and practical method to quantify the PAO and GAO populations in activated sludge systems, based on commonly measured and reliable analytical parameters (i.e., mixed liquor suspended solids, acetate, and orthophosphate) without requiring molecular techniques. This method relies on the estimation of the total active biomass population under anaerobic conditions (PAO plus GAO populations), by measuring the maximum acetate uptake rate in the presence of excess acetate. Later, the PAO and GAO populations present in the activated sludge system can be estimated, by taking into account the PAO/GAO ratio calculated on the basis of the anaerobic phosphorus release-to-acetate consumed ratio. The proposed method was evaluated using activated sludge from municipal wastewater treatment plants. The results from the quantification performed following the proposed method were compared with direct population estimations carried out with fluorescence in situ hybridization analysis (determining Candidatus Accumulibacter Phosphatis as PAO and Candidatus Competibacter Phosphatis as GAO). The method showed to be potentially suitable to estimate the PAO and GAO populations regarding the total PAO-GAO biomass. It could be used, not only to evaluate the performance of EBPR systems, but also in the calibration of potential activated sludge mathematical models, regarding the PAO-GAO coexistence.