Accumulation of organic and inorganic contaminants in shellfish collected in estuarine waters near Pensacola, Florida: contamination profiles and risks to human consumers

We conducted a screening level assessment of contaminants in blue crabs (Callinectes sapidus) and oysters (Crassostrea virginica) from bays and bayous in the Pensacola, FL area. Tissue samples were analyzed for 17 dioxins/furans, 12 dioxin-like PCB (DL-PCBs) congeners, mercury, and various metals. Contaminant levels were compared to screening values (SV) calculated using U.S. EPA recommendations for establishing consumption advisories. All sampling locations exceeded the SV (0.098pgg(-1)) for dioxins/furans/DL-PCBs, based on a Florida-specific consumption rate (46gday(-1)). Arsenic (inorganic), mercury, cadmium, and zinc levels exceeded SVs in samples from select locations, and with the exception of mercury, these locations were generally downstream of known contaminated areas. We also assessed potential human health risks from consumption of these species. Risks to human health were greatest from consumption of crab hepatopancreas, suggesting that consumption of hepatopancreas, whether directly or indirectly, from crabs collected anywhere in the Pensacola Bay region should be avoided.     

An experimental study of flame acceleration and deflagration to detonation transition in representative process piping

The paper summarizes the results of experimental tests and accompanying analyses to investigate the factors that govern flame acceleration and potential transition to detonation in a relatively long unobstructed piping system. The overall aim of the work was to obtain sufficient experimental data so as to be able to develop and evaluate methodologies for classifying and predicting potential detonation flame acceleration and deflagration to detonation transition (DDT) hazard in industrial process pipes and mixtures. The present results show that the flame acceleration process in an unobstructed pipe exhibit three distinct phases: an initial establishment phase; a second rapid acceleration phase and a final transition to detonation phase. Test results with ethylene indicate that the acceleration process is not sensitive to initial pressure (all other parameters remaining constant) but can be sensitivity to initial pipe wall temperature or possibly mixture humidity. The presence of bends increases the local rate of turbulent combustion, an effect attributed to the additional turbulence generated downstream of the bend. For straight pipes, detonation was only observed to develop for hydrogen–air and ethylene–air mixtures. Detonation was not observed with methane, propane or acetone as fuel in the present piping apparatus.     

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.     

What's the difference between reengineering and tqem?

Reengineering has become the latest corporate management buzzword, replacing, in many cases, total quality management as the panacea for industrial ills. How different are reengineering and total quality management (TQM), if at all, and how does each apply to environmental management? In this article the authors examine the concepts of reengineering and TQM as they apply to environmental management.     

Release of nitrogen and trace metal species from field stacked biosolids

Concerns over elevated nitrate (NO3-) levels found in groundwater near former biosolid stockpiling locations resulted in the Maine Department of Environmental Protection (MDEP) imposing stricter regulations governing the stockpiling of biosolids in October 2002. The goals of this study were to measure the amount and speciation of nitrogen (N) and trace metals leaving stockpiled biosolids and travelling through the soil column. The biosolids were placed on plastic-lined cells to collect all leachate. Ammonium (NH4+), ranging from 2000 to 4900 mg L(-1), was the dominant N species (90% of total N) in the leachate from the Class B lime-stabilized biosolids in the lined cell experiment. Nitrate (NO3-) and nitrite (NO2-) concentrations were negligible, remaining below 0.25 and 0.1 mg L(-1), respectively. Dissolved organic carbon (DOC) concentrations as high as 8900 mg L(-1) and chemical oxygen demand (COD) as high as 37 000 mg L(-1) were measured in the leachate leaving the lined cell. Fifteen zero-tension pan lysimeters (ZTP-lysimeter) were installed in a 90 m2 plot at depth intervals of 30, 60, and 100 cm. Leachate passing through the soil column underlying the biosolids stockpile was collected in the ZTP-lysimeters. The average ZTP-lysimeter NH4+ concentrations ranged from 1400 mg L(-1) at 60 cm depth to 145 mg L(-1) at 90 cm depth. The average ZTP-lysimeter DOC concentrations ranged from 2000 mg L(-1) at 60 cm to 525 mg L(-1) at 90 cm. Trace metal determinations of the leachate collected from the lined cell and ZTP-lysimeters showed arsenic loading rates exceeded the state limits of 0.5 kg ha(-1) year(-1) by an order of magnitude. Arsenic concentrations were in excess of several thousand milligrams per litre in the lined-cell leachate and several hundred milligrams per litre in the ZTP-lysimeters as deep as 90 cm under the biosolid stockpile. Phosphorus, iron and manganese in excess of several thousand milligrams per litre were observed in both the lined-cell leachate and ZTP-lysimeters. Significant concentrations of other trace metals were found at depth in the zero-tension ZTP-lysimeter plot. Trace metals were largely mobilized by the DOC from the biosolids and due to the presence of anaerobic environment, especially in the underlying soil.