Enhancement of PAH biomineralization rates by cyclodextrins under Fe(III)-reducing conditions

Amendment of a soil slurry with low concentrations of a cyclodextrin, hydroxypropyl-beta-cyclodextrin (HPCD), (0.05-0.5 g l(-1)) increased the phenanthrene mineralization rate of a microbial consortium by 25% under Fe(III)-reducing conditions. Although a higher concentration (5.0 g l(-1)) resulted in a faster initial rate of mineralization, mineralization ceased after 25 days with maximum mineralization 17% lower than the control (no HPCD). At lower HPCD concentrations, mineralization was still taking place at day 76. Although pH should affect Fe(III) solubility, mineralization rates at pH 6.0 and 8.0 were comparable. Decreasing the temperature reduced the extent and rate of mineralization, but mineralization rates at 10 degrees C were still 60% of that obtained at 30 degrees C.     

A SCALED HYDRAULIC MODEL OF THE PEACH BOTTOM ATOMIC POWER STATION DISCHARGE1

ABSTRACT: A scaled hydraulic model was used as a schematic representation of the Peach Bottom Atomic Power Station (PBAPS) discharge into Conowingo Pond during critically low river flows. The model approximated flow and temperature patterns and the degree of recirculation are assessed. Under normal operation the effluent is carried downstream and dissipated within about two miles. However, during dry weather years, river inflows can decrease substantially, resulting in unknown recirculation of effluent and flow patterns in Conowingo Pond. This study was conducted to investigate and predict flow patterns in Conowingo Pond under critically dry weather conditions. A threshold river flow is also identified that indicates a measure of the river's ability to maintain downstream advection of the effluent. The study suggests a number of unexpected current patterns, potential recirculation of the effluent, and changes in the dilution of the effluent.     

EFFECTS OF IMPROVED PRECIPITATION ESTIMATES ON AUTOMATED RUNOFF MAPPING: EASTERN UNITED STATES1

ABSTRACT: We evaluated maps of runoff created by means of two automated procedures. We implemented each procedure using precipitation estimates of both 5-km and 10-km resolution from PRISM (Parameter-elevation Regressions on Independent Slopes Model). Our goal was to determine if using the 5-km PRISM estimates would improve map accuracy. Visual inspection showed good general agreement among our runoff maps, as well as between our maps and one produced using a manual method. A quantitative uncertainty analysis comparing runoff interpolated from our maps with gage data that had been withheld showed slightly smaller actual and percentage interpolation errors for the 5-km PRISM-based maps. Our analyses suggest a modest region-wide improvement in runoff map accuracy with the use of PRISM-based precipitation estimates of 5-km (compared to 10-km) resolution.     

Calibration and Validation of ADAPT and SWAT for Field‐Scale Runoff Prediction1

Abstract: The pollutant reduction possible with a given agricultural best‐management practice (BMP) is complex and site‐specific. Water‐quality models can evaluate BMPs, but model results are often limited by the lack of calibrated parameters for a given BMP. This study calibrated runoff prediction of two models (ADAPT and SWAT) for individual field plots having one till and two no‐till management practices. The factors used for runoff calibration were curve number II (CN_II) and saturated hydraulic conductivity (Ksat) for ADAPT, and CN_II, Ksat, and available water capacity for SWAT. Results were evaluated using coefficient of determination (R²), Nash‐Sutcliffe efficiency (E_f), root‐mean square error, median‐based E_f, and sign tests. Results indicated that for ADAPT, the best‐fit CN_II was 66 for the NT/SB (no‐till plot with surface‐broadcast fertilizer) treatment, 68 for the NT/DB (no‐till with deep‐banded fertilizer) treatment, and 70 for the tilled plot, whereas for SWAT the best‐fit CN_II was much higher, 86, for all treatments. Neither agreed with the textbook CN_II, 78, for sorghum in silty clay loam soil. The best‐fit model parameters for both runoff calibration phases had excellent correlation to monthly totals and moderate correlation to individual events.     

Transforming China's coal mines: A case history of the Shuangliu Mine

China is the largest coal producer and the largest coal consuming country in the world. Approximately half of China's coal comes from small‐scale mines. The sustainability of China's coal industry would be improved if a greater share of the coal come from larger‐scale mines. This article presents a case history of the Shuangliu Mine in Shanxi Province and discusses the issues and benefits of the transformation of this mine. Significant gains were observed in worker safety and benefits, and in more efficient exploitation of the coal resource. Problems included loss of employment opportunities for local labourers, and reduced revenue for local townships. The wider implications of a shift of China's coal supply from small‐scale to large‐scale mining operations are discussed in relation to economic, social and environmental aspects.     

Escherichia coli loading at or near base flow in a mixed-use watershed

This study analyzed the occurrence of Escherichia coli in a mixed land-use watershed with human, cattle, and wildlife fecal inputs located in a karstic geologic region using synoptic monitoring (samples taken throughout the watershed system) during base-flow conditions. The objective of the study was to evaluate the occurrence of E. coli during base-flow conditions for several months at seven different main channel and nine different tributary sampling sites in the Stock Creek watershed, a 49.3-km(2) basin located in Knoxville, TN. Escherichia coli densities were measured using the Colilert (Defined Substrate Technology) method. The instantaneous loads for E. coli were determined from measured flow rates and E. coli densities, with the highest loading rates observed in the late fall. The study indicated a strong correlation between E. coli load rate (colony-forming units [CFU]/d), 7-d antecedent precipitation, and turbidity. Water quality data, however, also exhibited a spatial dependency; for example, the E. coli load rate was better correlated with turbidity in the slower draining basin tailwater sampling sites than in the faster draining upstream headwater sampling sites. In the headwater sites, the E. coli load rate was better correlated with 7-d antecedent precipitation than turbidity.     

The national GIS demonstrator of common lands for England and Wales

This paper describes the construction of a Geographical Information System (GIS) for common land tracts in England and Wales. In particular we highlight the problems inherent in combining data sets which have not been designed with GIS approaches in mind. The paper documents, through this case study, a number of key principles for researchers faced with developing databases of this nature and the limitations of the resulting database in the light of such concerns. In doing so, we draw attention to the types of techniques that can be developed to ensure users do not use the data in unwarranted situations and so guard against potential misuse. Such statements, it is concluded, are essential components in studies where data from several different sources are combined in a GIS environment to address rural planning issues.     

MATHEMATICAL GENERALIZATION OF STREAM TEMPERATURE IN CENTRAL NEW ENGLAND1

ABSTRACT: The empirical fit of an annual harmonic function to stream temperature measurements in central New England can be improved by considering a harmonic period of less than 365 days instead of 365 or 366 days. Generalized equations, developed using periodic temperature data from 27 streamflow stations, allow predictions of stream temperature at any site given (1) the mean basin altitude (E), in meters above mean sea level, and (2) station latitude (LAT), in degrees. Stream temperature t, in degrees Celsius, on day number d, in days starting with January 1, is estimated as: in which, M = 31.48 – 0.0025 (E) ? 0.4635 (LAT) with standard error of estimate of 0.62°C, and τ= 1228.88 – 21.01 (LAT) with standard error of estimate of 14.1 days.