In situ ammonia removal in bioreactor landfill leachate

Although bioreactor landfills have many advantages associated with them, challenges remain, including the persistence of NH(3)-N in the leachate. Because NH(3)-N is both persistent and toxic, it will likely influence when the landfill is biologically stable and when post-closure monitoring may end. An in situ nitrogen removal technique would be advantageous. Recent studies have shown the efficacy of such processes; however, they are lacking the data required to enable adequate implementation at field-scale bioreactor landfills. Research was conducted to evaluate the kinetics of in situ ammonia removal in both acclimated and unacclimated wastes to aid in developing guidance for field-scale implementation. Results demonstrate that in situ nitrification is feasible in an aerated solid waste environment and that the potential for simultaneous nitrification and denitrification (even under low biodegradable C:N conditions) in field-scale bioreactor landfills is significant due to the presence of both aerobic and anoxic areas. All rate data fit well to Monod kinetics, with specific rates of removal of 0.196 and 0.117 mgN/day-g dry waste and half-saturation constants of 59.6 and 147 mgN/L for acclimated and unacclimated wastes, respectively. Although specific rates of ammonia removal in the unacclimated waste are lower than in the acclimated waste, a relatively quick start-up of ammonia removal was observed in the unacclimated waste. Using the removal rate expressions developed will allow for estimation of the treatment times and volumes necessary to remove NH(3)-N from recirculated landfill leachate.     

Hot Spots of Perforated Forest in the Eastern United States

National assessments of forest fragmentation satisfy international biodiversity conventions, but they do not identify specific places where ecological impacts are likely. In this article, we identify geographic concentrations (hot spots) of forest located near holes in otherwise intact forest canopies (perforated forest) in the eastern United States, and we describe the proximate causes in terms of the nonforest land-cover types contained in those hot spots. Perforated forest, defined as a 0.09-ha unit of forest that is located at the center of a 7.29-ha neighborhood containing 60–99% forest with relatively low connectivity, was mapped over the eastern United States by using land-cover maps with roads superimposed. Statistically significant (P < 0.001) hot spots of high perforation rate (perforated area per unit area of forest) were then located by using a spatial scan statistic. Hot spots were widely distributed and covered 20.4% of the total area of the 10 ecological provinces examined, but 50.1% of the total hot-spot area was concentrated in only two provinces. In the central part of the study area, more than 90% of the forest edge in hot spots was attributed to anthropogenic land-cover types, whereas in the northern and southern parts it was more often associated with seminatural land cover such as herbaceous wetlands.     

ENHANCEMENTS OF NONPOINT SOURCE MONITORING OF VOLATILE ORGANIC COMPOUNDS IN GROUND WATER1

ABSTRACT: The U.S. Geological Survey (USGS) has compiled a national retrospective data set of analyses of volatile organic compounds (VOCs) in ground water of the United States. The data are from Federal, State, and local nonpoint‐source monitoring programs, collected between 1985–95. This data set is being used to augment data collected by the USGS National Water‐Quality Assessment (NAWQA) Program to ascertain the occurrence of VOCs in ground water nationwide. Eleven attributes of the retrospective data set were evaluated to determine the suitability of the data to augment NAWQA data in answering occurrence questions of varying complexity. These 11 attributes are the VOC analyte list and the associated reporting levels for each VOC, well type, well‐casing material, type of openings in the interval (screened interval or open hole), well depth, depth to the top and bottom of the open interval(s), depth to water level in the well, aquifer type (confined or unconfined), and aquifer lithology. VOCs frequently analyzed included solvents, industrial reagents, and refrigerants, but other VOCs of current interest were not frequently analyzed. About 70 percent of the sampled wells have the type of well documented in the data set, and about 74 percent have well depth documented. However, the data set generally lacks documentation of other characteristics, such as well‐casing material, information about the screened or open interval(s), depth to water level in the well, and aquifer type and lithology. For example, only about 20 percent of the wells include information on depth to water level in the well and only about 14 percent of the wells include information about aquifer type. The three most important enhancements to VOC data collected in nonpoint‐source monitoring programs for use in a national assessment of VOC occurrence in ground water would be an expanded VOC analyte list, recording the reporting level for each analyte for every analysis, and recording key ancillary information about each well. These enhancements would greatly increase the usefulness of VOC data in addressing complex occurrence questions, such as those that seek to explain the reasons for VOC occurrence and nonoccurrence in ground water of the United States.     

Evaluation and valuation of wildlife resources

Issues of resource conservation and development are essentially about choice between alternative uses of land. Resource evaluation in rural planning has usually been based on assessments of land quality or capability in relation to a variety of alternative uses. In the case of wildlife, choices have to be made as to whether the wildlife resource is worth conserving at all and if so, which sites should be used. Considerable efforts have been made to rationalise, improve and make explicit the way in which choices are made, and this paper reviews the current position and draws attention to issues and developments which could lead to improvements in current practice.     

Management and Limnology Interact to Drive Water Temperature Patterns in a Middle Rockies River‐Reservoir System

This study seeks to improve understanding of temperature patterns in reservoir outflows. We examined water temperatures in an irrigation storage reservoir, Island Park Reservoir, and its outflow, Henry’s Fork of the Snake River in eastern Idaho. Our objectives were to (1) quantify the extent to which daily temperature ranges in the reservoir outflow deviated from other reaches of the Henry’s Fork, and (2) test whether the reservoir’s net volume change during the summer — expressed as the volume of water remaining in the reservoir on September 1 — predicted mean summer temperature in the outflow. Two years of temperature data showed dampened diel temperature cycles in the reservoir outflow. Model selection with 17 years of climatic, hydrologic, and reservoir management variables found mean summer temperature in the outflow was best predicted by September 1 reservoir volume and average summer air temperature. Two years of weekly reservoir thermal profiles indicated large changes in reservoir volume eliminated cool hypolimnetic water and encouraged mixing, allowing warm epilimnetic water to be discharged into the outflow. Increases in future drought frequency and severity and increases in summer air temperatures could increase the frequency of occurrence of high mean summertime water temperatures in the outflow. Our study provides important information for local managers by quantifying influences on outflow temperatures and the downstream river ecosystem.     

Biodegradation of nitrogen-enriched lignite

Biodegradation of nitrogen-enriched lignite by soil bacteria previously acclimated in hydrogen peroxide-acetic acid lignitic substrate was carried out to assess the effects of nitrogen functional groups on the biodegradation of lignite. Chlorination, oxidation plus nitration, and ammoniation were applied in an attempt to modify the chemical structure of lignite so as to obtain a lignitic substrate that is more compatible to the enzymatical system of ordinary soil bacteria than that of unmodified lignite. Incorporation of nitrogen containing functional groups into lignite structure achieved 4.71 wt%, a value five times higher than that usually found in unmodified (raw) lignite. Data collected through a 16 day incubation time, monitoring production as well as depletion of both nitrate and organic acids, concluded that biodegradation was expedited by the incorporation of nitrogen into the structure of lignite. Twenty-eight compounds were identified based on the results from GC/MS analysis of the products.     

REAL-TIME SNOW SIMULATION MODEL FOR THE MONONGAHELA RIVER BASIN1

ABSTRACT: The Pittsburgh District, U.S. Army Corps of Engineers, is responsible for operating two multipurpose reservoirs in the 7384 square mile (19198 square kilometer) Monongahela Basin. A third reservoir, presently under construction, will soon be operating. The real-time forecasting of runoff for operational purposes requires simulation of snow accumulation and snowmelt throughout the Basin during the winter season. This article describes capabilities of SNOSIM, a model being developed for performing such simulation. The application of this model as part of a comprehensive system of water control software, and some initial simulation results are presented.     

Environmetrics to evaluate marine environment quality

The environmetric data analysis of analytical datasets from sediment and benthic organisms samples collected from different sampling sites along the coast of Black Sea near to City of Varna, Bulgaria has given some important indications about the bioindication properties of both type of samples. Various multivariate statistical methods like cluster analysis, principal components analysis, source apportioning modeling and partial least square (PLS) modeling were used in order to classify and interpret the parameters describing the chemical content of the coastal sediments (major components, heavy metals and total organic carbon) and benthic organisms (heavy metals). It has been shown that seriously polluted coastal zones are indicated in the same way by all benthic species, although some specificity could be detected for moderate polluted regions' e.g. polychaeta accumulated preferably Co, Cr, Cu, and Pb; crustacea - As, Cd, and Ni; mollusca - Zn. The identified latent factors responsible for the dataset structure are clearly indicated and apportioned with respect to their contribution to the total mass or total concentration of the species in the samples. The linear regression and PLS models indicated that a reliable forecast about the relation between naturally occurring chemical components and polluting species accumulated in the benthic organisms is possible.     

Geographic Variability in Radon Exhalation at a Rehabilitated Uranium Mine in the Northern Territory, Australia

In this study, dry season radon flux densities and radon fluxes have been determined at the rehabilitated Nabarlek uranium mine in northern Australia using conventional charcoal canisters. Environmental background levels amounted to 31± 15 milli Becquerel per m² per second (mBq m⁻² s⁻¹). Radon flux densities within the fenced rehabilitated mine area showed large variations with a maximum of 6500 mBq m⁻² s⁻¹ at an area south of the former pit characterised by a disequilibrium between ²²⁶Ra and ²³⁸U. Radon flux densities were also high above the areas of the former pit (mean 971 mBq m⁻² s⁻¹) and waste rock dump (mean 335 mBq m⁻² s⁻¹). The lower limit for the total pre-mining radon flux from the fenced area (140 ha) was estimated to 214 kBq s⁻¹, post-mining radon flux amounted to 174 kBq s⁻¹.Our study highlights that the results of radon flux studies are vitally dependant on the selection of individual survey points. We suggest the use of a randomised system for both the selection of survey points and the placement of charcoal canisters at each survey point, to avoid over estimation of radon flux densities. It is also important to emphasize the significance of having reliable pre-mining radiological data available to assess the success of rehabilitation of a uranium mine site.2006 Springer. The Australian Government's right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged.     

Standard purity and response factors of perfluorinated compounds

It has been reported that the relative response factors of isotopically labeled standards and unlabeled standards of the same perfluorinated compounds could be different. Individual (100 ng mL^?1) solutions of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) were analyzed using high-performance liquid chromatography tandem mass-spectrometry under negative-ion electrospray to detect any impurities present down to 0.5%–0.1% relative to the major component. Purity of the standards ranged from approximately 86% to ≥ 97%. Standard solutions of unlabeled and isotopically labeled materials were analyzed to compare the response factors of isotopically labeled analytes versus their nonlabeled counterparts in three different matrices at equivalent concentrations: organic solvent (methanol), serum extract, and water present individually and concurrently. Not all labeled analytes have the same response factor as their nonlabeled complement, and in at least one case the matrix in which the standard is present may cause significant suppression of response. Standard solutions of electrochemical fluorination produced PFOA and PFOS were quantified under multiple reaction monitoring mode, using calibration curves prepared from standards consisting primarily of linear standards only. The use of linear only standards may cause under-prediction of concentrations, and that the working range of these standards may be limited.