Analysis of six relevant toxaphene congeners in biological samples using ion trap MS/MS

Farmed and wild Scottish Atlantic salmon were obtained from retail suppliers, producers, and Stirling University in Scotland during January, 1999, for determination of 17 2,3,7,8-C1-substituted PCDDs and PCDFs, and seven nonortho- and mono-ortho-PCBs. The study confirms previous reports of relatively high concentrations of PCDDs, PCDFs and, especially, PCBs in farmed Scottish salmon. The results indicate that high consumption of salmon, particularly by children under 5 years, could lead to intakes above the tolerable daily intake (TDI) and tolerable weekly intake (TWI) for these chemicals, especially the PCBs, when combined with mean or high level intakes from the typical UK diet. These results suggest further investigation of farmed salmon and salmon feed, including feed fortified with fish oil and feed fortified with selected vegetable oils, is warranted.     

Full-scale class A biosolids production by two-stage continuous-batch thermophilic anaerobic digestion at the hyperion treatment plant, Los Angeles, California.

The City of Los Angeles Hyperion Treatment Plant (HTP) (California) converted its anaerobic digesters to thermophilic operation to produce Class A biosolids. Phase IV tests demonstrated compliance of a two-stage, continuous-batch process with Alternative 1 of U.S. Environmental Protection Agency 40 CFR Part 503 (U.S. EPA, 1993), which defines the time-temperature requirement for batch treatment (T > or = 56.3 degrees C at 16-h holding). Fecal coliforms, Salmonella sp., viable helminth ova, and enteric viruses were not detected in biosolids in the postdigestion train, including the truck-loading facility and the farm for land application as the last points of plant control where compliance is to be demonstrated. The same results were achieved during Phase V tests, after lowering the second-stage holding temperature to 52.6 degrees C to reduce the elevated methyl mercaptan production that was observed during Phase IV. Hence, the Phase V process complied with Alternative 3 of 40 CFR Part 503. Currently, HTP operates its digesters under the same conditions as tested in Phase V. In 2003, monthly monitoring of the biosolids at the truck-loading facility and the farm for land application demonstrated consistent compliance with Alternative 3.     

A cation exchange model to describe Cs+ sorption at high ionic strength in subsurface sediments at Hanford site, USA

A theoretical and experimental study of cation exchange in high ionic strength electrolytes was performed using pristine subsurface sediments from the U.S. Department of Energy Hanford site. These sediments are representative of the site contaminated sediments impacted by release of high level waste (HLW) solutions containing 137Cs+ in NaNO3 brine. The binary exchange behavior of Cs+-Na+, Cs+-K+, and Na+-K+ was measured over a range in electrolyte concentration. Vanselow selectivity coefficients (Kv) that were calculated from the experimental data using Pitzer model ion activity corrections for aqueous species showed monotonic increases with increasing electrolyte concentrations. The influence of electrolyte concentration was greater on the exchange of Na+-Cs+ than K+-Cs+, an observation consistent with the differences in ion hydration energy of the exchanging cations. A previously developed two-site ion exchange model [Geochimica et Cosmochimica Acta 66 (2002) 193] was modified to include solvent (water) activity changes in the exchanger phase through application of the Gibbs-Duhem equation. This water activity-corrected model well described the ionic strength effect on binary Cs+ exchange, and was extended to the ternary exchange system of Cs+-Na+-K+ on the pristine sediment. The model was also used to predict 137Cs+ distribution between sediment and aqueous phase (Kd) beneath a leaked HLW tank in Hanfordd's S-SX tank using the analytical aqueous data from the field and the binary ion exchange coefficients for the pristine sediment. The Kd predictions closely followed the trend in the field data and were improved by consideration of water activity effects that were considerable in certain regions of the vadose zone plume.     

STEP WISE,MULTIPLE OBJECTIVE CALIBRATION OF A HYDROLOGIC MODEL FOR A SNOWMELT DOMINATED BASIN1

ABSTRACT: The ability to apply a hydrologic model to large numbers of basins for forecasting purposes requires a quick and effective calibration strategy. This paper presents a step wise, multiple objective, automated procedure for hydrologic model calibration. This procedure includes the sequential calibration of a model's simulation of solar radiation (SR), potential evapotranspiration (PET), water balance, and daily runoff. The procedure uses the Shuffled Complex Evolution global search algorithm to calibrate the U.S. Geological Survey's Precipitation Runoff Modeling System in the Yampa River basin of Colorado. This process assures that intermediate states of the model (SR and PET on a monthly mean basis), as well as the water balance and components of the daily hydrograph are simulated consistently with measured values.     

Distribution and speciation of metals in annual rings of black willow

Information on the spatial distribution and speciation of metals in nonhyperaccumulator plants is lacking. This study used synchrotron X-ray fluorescence (SXRF) compositional imaging to investigate the spatial distribution of Ni, Mn, Cu, Zn, and Fe in annual rings of black willow (Salix nigra L.) collected from a metal-contaminated area, and used X-ray absorption spectroscopy (XAS) to investigate Ni and Mn speciation in regions of the annual rings with elevated Ni concentrations. Annual rings were recollected in early 2003 from an individual known to be enriched with Ni from previous studies. Compositional imaging showed Ni and associated co-contaminants conservatively located in an annual ring. When compared with a corresponding photomicrograph, SXRF compositional images showed that metals were sharply constrained by the boundaries of the annual ring, indicating a sudden onset and cessation of uptake, and a lack of post-growth mobility of the metals. There was a particularly strong correlation between Ni and Mn in the metal-enriched annual ring (r = 0.8822), which suggested similar transport and binding behavior of these elements. X-ray absorption spectroscopy showed Ni and Mn to be present in the 2+ oxidation state. X-ray absorption near edge structure spectroscopy (XANES) fingerprinting of localized, highly Ni-enriched regions within the lumen of willow xylem vessels found similarities with Ni-pectic acid complexes, Ni-histidine, and NiSO4.     

SERENDIPITY: CAPTURING A DESIGN LEVEL PRECIPITATION EVENT1

ABSTRACT: On February 23–24, 1998, a frontal system moved across the U.S. Department of Energy's 3,500 km² Nevada Test Site (NTS) and resulted in significant depths of precipitation at all recording gages on the NTS. A preliminary analysis suggested that this precipitation event was of the magnitude and duration for which many flood mitigation structures have been designed. Given the data and field observations available and the potential implications of the event on the methodologies used to size flood mitigation structures throughout the West, a detailed analysis of this event was undertaken. The goals of this study were to compare this event with the regulatory design precipitation event, compare the estimated peak flow rates from the rainfall/runoff model used to size the flood mitigation structures at a radioactive waste management site with the estimated peak flows from the precipitation event, and examine if modification of the standard source of the design depths of precipitation is warranted.     

建筑和建造部门:可持续的要素

在全球社会为实现真正的可持续性所做的努力中,建筑和建造业比其他产业部门的潜力可能都要大.……     

Evaluation of US EPA Environmental Monitoring and Assessment Program's (EMAP)-Wetlands sampling design and classification

The United States Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) will monitor the nation's resources by evaluating the status and trends of selected indicators of condition using a probability-based sampling design. The EMAP-Wetlands program will monitor the condition of the nation's wetlands. The EMAP classification system is an aggregation of the many subclasses of the US Fish and Wildlife Service's National Wetlands Inventory (NWI) classification system. This aggregation results in fewer wetland classes with more wetlands per class than the NWI system. Aggregation of the NWI classification was based primarily on dominant vegetation cover, flooding regimes, dominant water source, and adjacency to rivers and lakes. We evaluated the EMAP classification system and sampling design using NWI digital wetlands data for portions of Illinois, Washington, North Dakota, and South Dakata. Relative numbers of wetlands, total areas, average areas, and common versus rare classes were compared between the EMAP and NWI classification systems. As expected, the EMAP classification provided fewer wetland polygons, each with larger areas, without altering total wetland area. Summary statistics comparing sample estimates to true population parameters (represented by the NWI data) demonstrated the effectiveness of the EMAP sampling design with the exception of rare EMAP classes in the selected regions. Although simple random sampling is inadequate for both large and small wetlands, the EMAP sampling design is readily adapted to provide better estimates for these categories. Aggregating the NWI classification to the EMAP classification provides fewer wetland classes, with more wetlands per class, for EMAP's annual reports and statistical summaries. The research in this report has been funded by the United States Environmental Protection Agency (EPA) under contracts 68-C8-0006 to ManTech Environmental Technology, Inc. and 68-03-3532 to The Bionetics Corporation. Mention of trade names does not constitute endorsement or recommendation for use.     

Groundwater flow, multicomponent transport and biogeochemistry: development and application of a coupled process model

A research tool for modeling the reactive flow and transport of groundwater contaminants in multiple dimensions is presented. Arbitrarily complex coupled kinetic–equilibrium heterogeneous reaction networks, automatic code generation, transfer-function based solutions, parameter estimation, high-resolution methods for advection, and robust solvers for the mixed kinetic–equilibrium chemistry are some of the features of reactive flow and transport (RAFT) that make it a versatile research tool in the modeling of a wide variety of laboratory and field experiments. The treatment of reactions is quite general so that RAFT can be used to model biological, adsorption/desorption, complexation, and mineral dissolution/precipitation reactions among others. The integrated framework involving automated code generation and parameter estimation allows for the development, characterization, and evaluation of mechanistic process models. The model is described and used to solve a problem in competitive adsorption that illustrates some of these features. The model is also used to study the development of an in situ Fe(II)-zone by encouraging the growth of an iron-reducing bacterium with lactate as the electron donor. Such redox barriers are effective in sequestering groundwater contaminants such as chromate and TCE.