Measuring mining safety with injury statistics: lost workdays as indicators of risk

PROBLEM: Mining in the United States remains one of the most hazardous industries, despite significant reductions in fatal injury rates over the last century. Coal mine fatality rates, for example, have dropped almost a thousand-fold since their peak in 1908. While incidence rates are very important indicators, lost worktime measures offer an alternative metric for evaluating job safety and health performance. The first objective of this study examined the distributions and summary statistics of all injuries reported to the Mine Safety and Health Administration from 1983 through 2004. Over the period studied (1983-2004), there were 31,515,368 lost workdays associated with mining injuries, for an equivalent of 5,700 person-years lost annually. The second objective addressed the problem of comparing safety program performance in mines for situations where denominator data were lacking. By examining the consequences of injuries, comparisons can be made between disparate operations without the need for denominators. Total risk in the form of lost workday sums can help to distinguish between lower- and higher-risk operations or time periods. METHOD: Our method was to use a beta distribution to model the losses and to compare underground coal mining to underground metal/nonmetal mining from 2000 to 2004. RESULTS: Our results showed the probability of an injury having 10 or more lost workdays was 0.52 for coal mine cases versus 0.35 for metal/nonmetal mine cases. In addition, a comparison of injuries involving continuous mining machines over 2001-2002 versus 2003-2004 showed that the ratio of average losses in the later period to those in the earlier period was approximately 1.08, suggesting increasing risks for such operations. DISCUSSION: This denominator-free safety measure will help the mining industry more effectively identify higher-risk operations and more realistically evaluate their safety improvement programs. IMPACT ON INDUSTRY: Attention to a variety of metrics concerning the performance of a job safety and health program will enhance industry's ability to manage these programs and reduce risk.     

Light-mediated thresholds in stream-water nutrient composition in a river network

The elemental composition of solutes transported by rivers reflects combined influences of surrounding watersheds and transformations within stream networks, yet comparatively little is known about downstream changes in effects of watershed loading vs. in-channel processes. In the forested watershed of a river under a mediterranean hydrologic regime, we examined the influence of longitudinal changes in environmental conditions on water-column nutrient composition during summer base flow across a network of sites ranging from strongly heterotrophic headwater streams to larger, more autotrophic sites downstream. Small streams (0.1-10 km2 watershed area) had longitudinally similar nutrient concentration and composition with low (approximately 2) dissolved nitrogen (N) to phosphorus (P) ratios. Abrupt deviations from this pattern were observed in larger streams with watershed areas > 100 km2 where insolation and algal abundance and production rapidly increased. Downstream, phosphorus and silica concentrations decreased by > 50% compared to headwater streams, and dissolved organic carbon and nitrogen increased by approximately 3-6 times. Decreasing dissolved P and increasing dissolved N raised stream-water N:P to 46 at the most downstream sites, suggesting a transition from N limitation in headwaters to potential P limitation in larger channels. We hypothesize that these changes were mediated by increasing algal photosynthesis and N fixation by benthic algal assemblages, which, in response to increasing light availability, strongly altered stream-water nutrient concentration and stoichiometry in larger streams and rivers.     

Trait-mediated effects on flowers: artificial spiders deceive pollinators and decrease plant fitness

Although predators can affect foraging behaviors of floral visitors, rarely is it known if these top-down effects of predators may cascade to plant fitness through trait-mediated interactions. In this study we manipulated artificial crab spiders on flowers of Rubus rosifolius to test the effects of predation risk on flower-visiting insects and strength of trait-mediated indirect effects to plant fitness. In addition, we tested which predator traits (e.g., forelimbs, abdomen) are recognized and avoided by pollinators. Total visitation rate was higher for control flowers than for flowers with an artificial crab spider. In addition, flowers with a sphere (simulating a spider abdomen) were more frequently visited than those with forelimbs or the entire spider model. Furthermore, the presence of artificial spiders decreased individual seed set by 42% and fruit biomass by 50%. Our findings indicate that pollinators, mostly bees, recognize and avoid flowers with predation risk; forelimbs seem to be the predator trait recognized and avoided by hymenopterans. Additionally, predator avoidance by pollinators resulted in pollen limitation, thereby affecting some components of plant fitness (fruit biomass and seed number). Because most pollinator species that recognized predation risk visited many other plant species, trait-mediated indirect effects of spiders cascading down to plant fitness may be a common phenomenon in the Atlantic rainforest ecosystem.     

Imidacloprid residues in fruits,vegetables and water samples from Palestine

The aim of this work was to report on imidacloprid [IUPAC name 1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine] residues in some vegetables, fruits, and water samples collected from the West Bank, Palestine, in 1998 and 1999. Imidacloprid and its derivatives in the study samples were extracted by methanol/water and oxidized into 6-chloronicotinic acid and subsequently derivatized into 6-chloronicotinic acid trimethylsilyl ester before being determined by GC/MS. Imidacloprid residues were detected in more than half of the analyzed samples. The highest and lowest imidacloprid concentrations were found in eggplant (0.46 mg/kg) and green beans (0.08 mg/kg), respectively. An increase of 11–120% in imidacloprid concentration in the 1999 samples was observed when compared with those of 1998. This may suggest imidacloprid accumulation in the soil and/or increased use by local farmers. The imidacloprid residue concentrations in several crops were found to exceed the CODEX maximum residue limit.     

Monitoring Changes in Freshwater Macroinvertebrate Communities Along a Salinity Gradient Using Artificial Substrates

Scientists strive to develop efficient sampling protocols, reducing both the number of samples and processing time required, which can be adapted for use in a broad range of ecosystems. We investigated the accuracy and usefulness of artificial substrates in monitoring the impact of rising salinity on freshwater macroinvertebrate communities. We sampled seven sites along a salinity gradient (from 0.2gL^-1 to 2.6gL^-1) over a 19-km stretch of the Meurthe River, in northeastern France. All other parameters remained stable in this section of the river. Artificial substrate samples, each consisting of six liters of pebbles, were removed from the river at one-month intervals and examined. Results obtained indicated the same qualitative impairments as those found in samples collected using a Surber net. The use of artificial substrates was found to be a viable alternative method for assessing biological changes in river quality due to increasing salinity disturbance when Surber sampling cannot be performed.     

Antibiotic Transport via Runoff and Soil Loss

Research has verified the occurrence of veterinary antibiotics in manure, agricultural fields, and surface water bodies, yet little research has evaluated antibiotic runoff from agricultural fields. The objective of this study was to evaluate the potential for agricultural runoff to contribute antibiotics to surface water bodies in a worst-case scenario. Our hypothesis was that there would be significant differences in antibiotic concentrations, partitioning of losses between runoff and sediment, and pseudo-partitioning coefficients (ratio of sediment concentration to runoff concentration) among antibiotics. An antibiotic solution including tetracycline (TC), chlortetracycline (CTC), sulfathiazole (STZ), sulfamethazine (SMZ), erythromycin (ERY), tylosin (TYL), and monensin (MNS) was sprayed on the soil surface 1 h before rainfall simulation (average intensity = 60 mm h(-1) for 1 h). Runoff samples were collected continuously and analyzed for aqueous and sediment antibiotic concentrations. MNS had the highest concentration in runoff, resulting in the highest absolute loss, although the amount of loss associated with sediment transport was <10%. ERY had the highest concentrations in sediment and had a relative loss associated with sediment >50%. TYL also had >50% relative loss associated with sediment, and its pseudo-partitioning coefficient (P-PC) was very high. The tetracyclines (TC and CTC) had very low aqueous concentrations and had the lowest absolute losses. If agricultural runoff is proven to result in development of resistance genes or toxicity to aquatic organisms, then erosion control practices could be used to reduce TC, ERY, and TYL losses leaving agricultural fields. Other methods will be needed to reduce transport of other antibiotics.     

Bias of Tedlar bags in the measurement of agricultural odorants

Odor regulations typically specify the use of dynamic dilution olfactometery (DDO) as a method to quantify odor emissions, and Tedlar bags are the preferred holding container for grab samples. This study was conducted to determine if Tedlar bags affect the integrity of sampled air from animal operations. Air samples were collected simultaneously in both Tedlar bags and Tenax thermal desorption tubes. Sample sources originated from either a hydrocarbon-free air tank, dynamic headspace chamber (DHC), or swine-production facility, and were analyzed by gas chromatography-mass spectrometry-olfactometry (GC-MS-O). Several background contaminants were identified from Tedlar bags, which included the odorous compounds N,N-dimethyl acetamide (DMAC), acetic acid, and phenol. Samples from the DHC demonstrated that recovery of malodor compounds was dependent on residence time in the Tedlar bag with longer residence time leading to lower recovery. After 24 h of storage, recovery of C3-C6 volatile fatty acids (VFA) averaged 64%, 4-methylphenol and 4-ethylphenol averaged 10%, and indole and 3-methylindole were below the detection limits of GC-MS-O. The odor activity value (OAV) of grab samples collected in Tedlar bags were 33 to 65% lower following 24 h of storage. These results indicate that significant odorant bias occurs when using Tedlar bags for the sampling of odors from animal production facilities.     

Environmental and economic analysis of switchgrass production for water quality improvement in northeast Kansas

The primary objectives of this research were to determine SWAT model predicted reductions in four water quality indicators (sediment yield, surface runoff, nitrate nitrogen (NO(3)-N) in surface runoff, and edge-of-field erosion) associated with producing switchgrass (Panicum virgatum) on cropland in the Delaware basin in northeast Kansas, and evaluate switchgrass break-even prices. The magnitude of potential switchgrass water quality payments based on using switchgrass as an alternative energy source was also estimated. SWAT model simulations showed that between 527,000 and 1.27 million metric tons (Mg) of switchgrass could be produced annually across the basin depending upon nitrogen (N) fertilizer application levels (0-224 kg N ha(-1)). The predicted reductions in sediment yield, surface runoff, NO(3)-N in surface runoff, and edge-of-field erosion as a result of switchgrass plantings were 99, 55, 34, and 98%, respectively. The average annual cost per hectare for switchgrass ranged from about 190 US dollars with no N applied to around 345 US dollars at 224 kg N ha(-1) applied. Edge-of-field break-even price per Mg ranged from around 41 US dollars with no N applied to slightly less than 25 US dollars at 224 kg N ha(-1) applied. A majority of the switchgrass produced had an edge-of-field break-even price of 30 Mg(-1) US dollars or less. Savings of at least 50% in each of the four water quality indicators could be attained for an edge-of-field break-even price of 22-27.49 US dollars Mg(-1).     

Alternative scenarios to meet the demands of sustainable waste management

This paper analyses different alternatives for solid waste management that can be implemented to enable the targets required by the European Landfill and Packaging and Packaging Waste Directives to be achieved in the Valencian Community, on the east coast of Spain. The methodology applied to evaluate the environmental performance of each alternative is Life Cycle Assessment (LCA). The analysis has been performed at two levels; first, the emissions accounted for in the inventory stage have been arranged into impact categories to obtain an indicator for each category; and secondly, the weighting of environmental data to a single unit has been applied. Despite quantitative differences between the results obtained with four alternative impact assessment methods, the same preference ranking has been established: scenarios with energy recovery (1v and 2v) achieve major improvements compared to baseline, with scenario 1v being better than 2v for all impact assessment methods except for the EPS'00 method, which obtains better results for scenario 2v. Sensitivity analysis has been used to test some of the assumptions used in the initial life cycle inventory model but none have a significant effect on the overall results. As a result, the best alternative to the existing waste management system can be identified.     

Overland flow model for asphalt oil spills

Along the asphalt production line, the hot asphalt oil needs to undergo a cooling process that involves temporary storage in a tank. Safety is always a concern as to what if the tank is ruptured. Scenario studies of asphalt oil spills are required when designing the layout and open space for such a cooling process in the refinery yard. Applying the laminar flow theory to an asphalt oil spill, this paper presents an overland flow model to calculate the possible range of spread. The major parameters used in this model include fluid viscosity, ground slope, hydraulic conveyance, and asphalt oil volume. As a simplified model for a quasi-steady state flow condition, a hot asphalt oil spill for a typical case in a refinery yard can run approximately 400 to 600 feet before the asphalt mass cools down and becomes solid-like.