bluuebunny/crossref_metadata_2025_split huggingface dataset:
A hybrid empirical-mechanistic modeling approach for extrapolating biota–sediment accumulation factors and bioaccumulation factors across species, time, and/or ecosystems
Authors: Burkhard Lawrence P. , Cook Philip M. , Lukasewycz Marta T. 
Published: July 2006

AbstractAn approach is presented for extrapolating field-measured biota–sediment accumulation factors (BSAFs) and bioaccumulation factors (BAFs) across species, time, and/or ecosystems. This approach, called the hybrid bioaccumulation modeling approach, uses mechanistic bioaccumulation models to extrapolate field-measured bioaccumulation data (i.e., BSAFs and BAFs) to new sets of ecological conditions. The hybrid approach predicts relative differences in bioaccumulation using food web models with two sets of ecological conditions and parameters: One set for the ecosystem where the BSAFs and/or BAFs were measured, and the other set for the ecological conditions and parameters for which the extrapolated BSAFs and/or BAFs are desired. The field-measured BSAF (or BAF) is extrapolated by adjusting the measured BSAF (or BAF) by the predicted relative difference, which is derived from two separate solutions of the food web model. Extrapolations of polychlorinated biphenyl BSAFs and BAFs for lake trout (Salvelinus namaycush) from southern Lake Michigan to Green Bay of Lake Michigan (Green Bay, WI, USA) walleye (Stizostedion vitreum) and brown trout (Salmo trutta), as well as Hudson River largemouth bass (Micropterus salmoides) and yellow perch (Perca flavescens), resulted in generally better agreement between measured and predicted BSAFs and BAFs with the hybrid approach.
Dietary accumulation of hexabromocyclododecane diastereoisomers in juvenile rainbow trout (Oncorhynchus mykiss) I: Bioaccumulation parameters and evidence of bioisomerization
Authors: Law Kerri , Palace Vince P. , Halldorson Thor , Danell Robert , Wautier Kerry , Evans Bob , Alaee Mehran , Marvin Chris , Tomy Gregg T. 
Published: July 2006

Abstract
Juvenile rainbow trout (Oncorhynchus mykiss) were exposed to three diastereoisomers (α, β, γ) of hexabromocyclododecane (C12H18Br6) via their diet for 56 d followed by 112 d of untreated food to examine bioaccumulation parameters and test the hypothesis of in vivo bioisomerization. Four groups of 70 fish were used in the study. Three groups were exposed to food fortified with known concentrations of an individual diastereoisomer, while a fourth group were fed unfortified food. Bioaccumulation of the γ-diastereoisomer was linear during the uptake phase, while the α- and β-diastereoisomers were found to increase exponentially with respective doubling times of 8.2 and 17.1 d. Both the β- and the γ-diastereoisomers followed a first-order depuration kinetics with calculated half-lives of 157 ± 71 and 144 ± 60 d (±1 × standard error), respectively. The biomagnification factor (BMF) for the α-diastereoisomer (BMF = 9.2) was two times greater than the β-diastereoisomer (BMF = 4.3); the large BMF for the α-diastereoisomer is consistent with this diastereoisomer dominating higher-trophic-level organisms. Although the BMF of the β-diastereoisomer suggests that it will biomagnify, it is rarely detected in environmental samples because it is present in small quantities in commercial mixtures. Results from these studies also provide evidence of bioisomerization of the β- and γ-diastereoisomers. Most importantly, the α-diastereoisomer that was recalcitrant to bioisomerization by juvenile rainbow trout in this study and known to be the dominant diastereosiomer in fish was bioformed from both the β- and the γ-diastereoisomers. To our knowledge, this is the first report of bioisomerization of a halogenated organic pollutant in biota.
Behavior of B, Cr, Se, As, Pb, Cd, and Mo present in waste leachates generated from combustion residues during the formation of ettringite
Authors: Saikia Nabajyoti , Kato Shigeru , Kojima Toshinori 
Published: July 2006

Abstract
The behavior of B, Cr, Se, As, Pb, Cd, and Mo in the leachates generated from two combustion residues, coal-fired power plant fly ash and municipal solid waste incineration ash, during precipitation of ettringite is presented. Experiments also were performed using modeled waste leachates as well as controlled solutions containing all the investigated elements. Moreover, to determine the possible effect of pH, lime treatment was conducted using the waste and modeled leachates. Results indicated the removal of B, Se, and Cr from the leachates because of incorporation of their oxyanions in the ettringite structure. The removal of B could further be explained by considering the structure of ettringite and monosulfoaluminate. The removal of Pb also occurred, probably because of lime-induced precipitation of Pb(OH)2. Similarly, the removal of As was observed as a result of lime-induced precipitation of Ca3(AsO4)2 and incorporation into the ettringite structure. On the other hand, the precipitation of ettringite did not reduce the concentrations of Mo and Cd because of the complex nature of these elements in the leachates. The results also suggest that the presence of high amounts of constituents such as Cl−, an alkali metal in the solution, also affected ettringite precipitation behavior. Moreover, elemental speciations as well as the presence of other constituents in the solution affected the incorporation by ettringite.
Economic Feasibility of No‐Tillage and Manure for Soil Carbon Sequestration in Corn Production in Northeastern Kansas
Authors: Pendell Dustin L. , Williams Jeffery R. , Rice Charles W. , Nelson Richard G. , Boyles Scott B. 
Published: July 2006

ABSTRACTThis study examined the economic potential of no‐tillage versus conventional tillage to sequester soil carbon by using two rates of commercial N fertilizer or beef cattle manure for continuous corn (Zea mays L.) production. Yields, input rates, field operations, and prices from an experiment were used to simulate a distribution of net returns for eight production systems. Carbon release values from direct, embodied, and feedstock energies were estimated for each system, and were used with soil carbon sequestration rates from soil tests to determine the amount of net carbon sequestered by each system. The values of carbon credits that provide an incentive for managers to adopt production systems that sequester carbon at greater rates were derived. No‐till systems had greater annual soil carbon gains, net carbon gains, and net returns than conventional tillage systems. Systems that used beef cattle manure had greater soil carbon gains and net carbon gains, but lower net returns, than systems that used commercial N fertilizer. Carbon credits would be needed to encourage the use of manure‐fertilized cropping systems.
Soil Organic Carbon and Nitrogen Accumulation in Plots of Rhizoma Perennial Peanut and Bahiagrass Grown in Elevated Carbon Dioxide and Temperature
Authors: Allen Leon Hartwell , Albrecht Stephan L. , Boote Kenneth J. , Thomas Jean M. G. , Newman Yoana C. , Skirvin Katherine W. 
Published: July 2006

ABSTRACTCarbon sequestration in soils might mitigate the increase of carbon dioxide (CO2) in the atmosphere. Two contrasting subtropical perennial forage species, bahiagrass (BG; Paspalum notatum Flügge; C4), and rhizoma perennial peanut (PP; Arachis glabrata Benth.; C3 legume), were grown at Gainesville, Florida, in field soil plots in four temperature zones of four temperature‐gradient greenhouses, two each at CO2 concentrations of 360 and 700 μmol mol−1 The site had been cultivated with annual crops for more than 20 yr. Herbage was harvested three to four times each year. Soil samples from the top 20 cm were collected in February 1995, before plant establishment, and in December 2000 at the end of the project. Overall mean soil organic carbon (SOC) gains across 6 yr were 1.396 and 0.746 g kg−1 in BG and PP, respectively, indicating that BG plots accumulated more SOC than PP. Mean SOC gains in BG plots at 700 and 360 μmol mol−1 CO2 were 1.450 and 1.343 g kg−1, respectively (not statistically different). Mean SOC gains in PP plots at 700 and 360 μmol mol−1 CO2 were 0.949 and 0.544 g kg−1, respectively, an increase caused by elevated CO2 Relative SON accumulations were similar to SOC increases. Overall mean annual SOC accumulation, pooled for forages and CO2 treatments, was 540 kg ha−1 yr−1 Eliminating elevated CO2 effects, overall mean SOC accumulation was 475 kg ha−1 yr−1 Conversion from cropland to forages was a greater factor in SOC accumulation than the CO2 fertilization effect.
Greenhouse Gas Emissions from Forestry Operations
Authors: Sonne Edie 
Published: July 2006

ABSTRACTMost forest carbon assessments focus only on biomass carbon and assume that greenhouse gas (GHG) emissions from forestry activities are minimal. This study took an in‐depth look at the direct and indirect emissions from Pacific Northwest (PNW) Douglas‐fir [Pseudotsuga menziesii (Mirbel) Franco] forestry activities to support or deny this claim. Greenhouse gas budgets for 408 “management regimes” were calculated using Life Cycle Assessment (LCA) methodology. These management regimes were comprised of different combinations of three types of seedlings (P + 1, 1 + 1, and large plug), two types of site preparation (pile and burn, and chemical), 17 combinations of management intensity including fertilization, herbicide treatment, pre‐commercial thinning (PCT), commercial thinning (CT), and nothing, and four different rotation ages (30, 40, 50, and 60 yr). Normalized to 50 yr, average direct GHG emissions were 8.6 megagrams (Mg) carbon dioxide equivalents (CO2e) ha−1, which accounted for 84% of total GHG emissions from the average of 408 management regimes. Harvesting (PCT, CT, and clear cutting) contributed the most to total GHG emissions (5.9 Mg CO2e per 700 m3 harvested timber), followed by pile and burn site preparation (4.0 Mg CO2e ha−1 or 32% of total GHG emissions) and then fertilization (1.9 Mg CO2e ha−1 or 15% of total GHG emissions). Seedling production, seedling transportation, chemical site preparation, and herbicide treatment each contributed less than 1% of total GHG emissions when assessed per hectare of planted timberland. Total emissions per 100 m3 averaged 1.6 Mg CO2e ha−1 over all 408 management regimes. An uncertainty analysis using Monte Carlo simulations revealed that there are significant differences between most alternative management regimes.
Free‐Air Carbon Dioxide Enrichment of Soybean
Authors: Prior S. A. , Torbert H. A. , Runion G. B. , Rogers H. H. , Ort D. R. , Nelson R. L. 
Published: July 2006

ABSTRACTElevated atmospheric CO2 can result in larger plants returning greater amounts of residue to the soil. However, the effects of elevated CO2 on carbon (C) and nitrogen (N) cycling for different soybean varieties have not been examined. Aboveground residue of eight soybean [Glycine max (L.) Merr.] varieties was collected from a field study where crops had been grown under two different atmospheric CO2 levels [370 μmol mol−1 (ambient) and 550 μmol mol−1 (free‐air carbon dioxide enrichment, FACE)]. Senesced residue material was used in a 60‐d laboratory incubation study to evaluate potential C and N mineralization. In addition to assessing the overall effects of CO2 level and variety, a few specific variety comparisons were also made. Across varieties, overall residue N concentration was increased by FACE, but residue C concentration was only slightly increased. Overall residue C to N ratio was lower under FACE and total mineralized N was increased by FACE, suggesting that increased N2 fixation impacted residue decomposition; total mineralized C was also slightly increased by FACE. Across CO2 levels, varietal differences were also observed with the oldest variety having the lowest residue N concentration and highest residue C to N ratio; mineralized N was lowest in the oldest variety, illustrating the influence of high residue C to N ratio. It appears (based on our few specific varietal comparisons) that the breeding selection process may have resulted in some varietal differences in residue quality which can result in increased N or C mineralization under elevated CO2 conditions. This limited number of varietal comparisons indicated that more work investigating varietal influences on soil C and N cycling under elevated CO2 conditions is required.
Carbon Accounting Rules and Guidelines for the United States Forest Sector
Authors: Birdsey Richard A. 
Published: July 2006

ABSTRACTThe United States Climate Change Initiative includes improvements to the U.S. Department of Energy's Voluntary Greenhouse Gas Reporting Program. The program includes specific accounting rules and guidelines for reporting and registering forestry activities that reduce atmospheric CO2 by increasing carbon sequestration or reducing emissions. In the forestry sector, there is potential for the economic value of emissions credits to provide increased income for landowners, to support rural development, to facilitate the practice of sustainable forest management, and to support restoration of ecosystems. Forestry activities with potential for achieving substantial reductions include, but are not limited to: afforestation, mine land reclamation, forest restoration, agroforestry, forest management, short‐rotation biomass energy plantations, forest protection, wood production, and urban forestry. To be eligible for registration, the reported reductions must use methods and meet standards contained in the guidelines. Forestry presents some unique challenges and opportunities because of the diversity of activities, the variety of practices that can affect greenhouse gases, year‐to‐year variability in emissions and sequestration, the effects of activities on different forest carbon pools, and accounting for the effects of natural disturbance.
Assessing Alternatives for Mitigating Net Greenhouse Gas Emissions and Increasing Yields from Rice Production in China Over the Next Twenty Years
Authors: Li Changsheng , Salas William , DeAngelo Benjamin , Rose Steven 
Published: July 2006

ABSTRACTAssessments of the efficacy of mitigation of greenhouse gas (GHG) emissions from paddy rice systems have typically been analyzed based on field studies. Extrapolation of the mitigation potential of alternative management practices from field studies to a national scale may be enhanced by spatially explicit process models, like the DeNitrification and DeComposition (DNDC) model. Our objective was to analyze the impacts of mitigation alternatives, management of water, fertilizer, and rice straw, on net GHG emissions (carbon dioxide, methane, and nitrous oxide fluxes), yields, and water use. After constructing a GIS database of soil, climate, rice cropping area and systems, and management practices, we ran DNDC with 21‐yr alternative management schemes for each of the approximately 2500 counties in China. Results indicate that, despite large‐scale adoption of midseason drainage, there is still large potential for additional methane reductions from Chinese rice paddies of 20 to 60% over 2000–2020. However, changes in management for reducing CH4 emissions simultaneously affect soil carbon dynamics as well as N2O emissions and can thereby reorder the ranking of technical mitigation effectiveness. The order of net GHG emissions reduction effectiveness found here is upland rice > shallow flooding > ammonium sulfate > midseason drainage > off‐season straw > slow‐release fertilizer > continuous flooding. Most of the management alternatives produced yields comparable to the baseline; however, continuous flooding and upland rice significantly reduced yields. Water management strategies appear to be the most technically promising GHG mitigation alternatives, with shallow flooding providing additional benefits of both water conservation and increased yields.
Root Penetration of Sealing Layers Made of Fly Ash and Sewage Sludge
Authors: Neuschütz Clara , Stoltz Eva , Greger Maria 
Published: July 2006

ABSTRACTFly ash and sewage sludge are suggested materials for constructing sealing layers covering mine tailings impoundments. Little is known, however, of their effect on vegetation or resistance to root penetration. We investigate: (i) the ability of different plant species to grow in sealing layers comprising fly ash and sewage sludge, (ii) the impact on plant growth of freshly hardened fly ash compared to aged and leached ash, and (iii) the plant stress response to fly ashes of different properties. A 6‐mo greenhouse study using birch (Betula pendula Roth.), Scots pine (Pinus sylvestris L.), Kentucky bluegrass (Poa pratensis L.), and willow (Salix viminalis L.) demonstrated that no roots could grow into a compacted layer consisting only of ash, while a 6:4, ash–sludge mixture admitted roots into the upper part and a 1:9, ash–sludge mixture was totally penetrated (to 15 cm in depth) by roots of willow and Scots pine. Freshly hardened ash prevented root growth more effectively than aged ash did, as was observed in tests using reed canarygrass (Phalaris arundinacea L.) and pea (Pisum sativum L.). Furthermore, extracts of highly alkaline ash were more toxic to pea in a 48‐h toxicity test than less alkaline ash was. However, stress responses to diluted ash extracts of lower pH, measured as enzyme capacities in dwarf bean (Phaseolus vulgaris L.), were more related to the metal and ion contents. Root penetration of sealing layers is most effectively prevented if little sewage sludge is added, and if ash of high alkalinity is chosen.
Distance and Flow Effects on Microsphere Transport in a Large Gravel Column
Authors: Close Murray E. , Pang Liping , Flintoft Mark J. , Sinton Lester W. 
Published: July 2006

ABSTRACTConsumption of microbially contaminated ground water can cause adverse health effects and the processes involved in pathogen transport in aquifers need to be understood. The influences of distance, flow velocity, and colloid size on colloid transport were examined in homogenous pea‐gravel media using an 8‐m column and three sizes (1, 5, and 10 μm) of microspheres. Experiments were conducted at three flow rates by simultaneously injecting microspheres with a conservative tracer, bromide. Observed concentrations were simulated with CXTFIT and analyzed with filtration theory. The results demonstrate that colloid concentration is strongly log‐linearly related to transport distance (as suggested by filtration theory) in coarse gravels, similar to our previous field studies. In contrast, the log‐linear relationship is often reported to be invalid in fine porous media. The observed log‐linear relationship is possibly because straining is negligible in the coarse gravels investigated. This has implications in predicting setback distances for land disposal of effluent, and suggests that setback distances in gravel aquifers can be estimated using constant spatial removal rates (f). There was an inverse relationship between transport distance and colloidal concentration, but not with temporal attachment rate (katt) and collision coefficient (α). Increases in flow velocity result in increasing colloidal recovery, katt and α but decreasing f Increases in sphere size result in decreasing colloidal recovery with increasing katt, f, α, and velocity enhancement. Diffusion is the dominant collision mechanism for 1‐μm spheres (81–88%), while settling dominates for 5‐ and 10‐μm spheres (>87%), and interception is very small for all spheres investigated.
Microbial Populations Identified by Fluorescence In Situ Hybridization in a Constructed Wetland Treating Acid Coal Mine Drainage
Authors: Nicomrat Duongruitai , Dick Warren A. , Tuovinen Olli H. 
Published: July 2006

ABSTRACTMicroorganisms are an integral part of the biogeochemical processes in wetlands, yet microbial communities in sediments within constructed wetlands receiving acid mine drainage (AMD) are only poorly understood. The purpose of this study was to characterize the microbial diversity and abundance in a wetland receiving AMD using fluorescence in situ hybridization (FISH) analysis. Seasonal samples of oxic surface sediments, comprised of Fe(III) precipitates, were collected from two treatment cells of the constructed wetland system. The pH of the bulk samples ranged between pH 2.1 and 3.9. Viable counts of acidophilic Fe and S oxidizers and heterotrophs were determined with a most probable number (MPN) method. The MPN counts were only a fraction of the corresponding FISH counts. The sediment samples contained microorganisms in the Bacteria (including the subgroups of acidophilic Fe‐ and S‐oxidizing bacteria and Acidiphilium spp.) and Eukarya domains. Archaea were present in the sediment surface samples at <0.01% of the total microbial community. The most numerous bacterial species in this wetland system was Acidithiobacillus ferrooxidans, comprising up to 37% of the bacterial population. Acidithiobacillus thiooxidans was also abundant. Heterotrophs in the Acidiphilium genus totaled 20% of the bacterial population. Leptospirillum ferrooxidans was below the level of detection in the bacterial community. The results from the FISH technique from this field study are consistent with results from other experiments involving enumeration by most probable number, dot‐blot hybridization, and denaturing gradient gel electrophoresis analyses and with the geochemistry of the site.
Nitrogen and Phosphorus Attenuation within the Stream Network of a Coastal, Agricultural Watershed
Authors: Ensign Scott H. , McMillan Sara K. , Thompson Suzanne P. , Piehler Michael F. 
Published: July 2006

ABSTRACTStreams alter the concentration of nutrients they transport and thereby influence nutrient loading to estuaries downstream; however, the relationship between in‐stream uptake, discharge variability, and subsequent nutrient export is poorly understood. In this study, in‐stream N and P uptake were examined in the stream network draining a row‐crop agricultural operation in coastal North Carolina. The effect of in‐stream nutrient uptake on estuarine loading was examined using continuous measurements of watershed nutrient export. From August to December 2003, 52 and 83% of the NH4+ and PO43− loads were exported during storms while concurrent storm flow volume was 34% of the total. Whole‐ecosystem mass transfer velocities (Vf) of NH4+ and PO43−, measured using short‐term additions of inorganic nutrients, ranged from 0.1 to 25 mm min−1 Using a mass balance approach, this in‐stream uptake was found to attenuate 65 to 98% of the NH4+ flux and 78 to 98% of the PO43− flux in small, first‐order drainage ditches. For the larger channel downstream, an empirical model based on Vf and discharge was developed to estimate the percentage of the nutrient load retained in‐stream. The model predicted that all of the upstream NH4+ and PO43− load was retained during base flow, while 65 and 37% of the NH4+ and PO43− load was retained during storms. Remineralization from the streambed (vs. terrestrial sources) was the apparent source of NH4+ and PO43− to the estuary during base flow. In‐stream uptake reduced the dissolved inorganic N to dissolved inorganic P ratio of water exported to the N‐limited estuary, thus limiting the potential for estuarine phytoplankton growth.