bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interaction between Nitrous Oxide Formation and Methane Oxidation in Soils: Influence of Cation Exchange Phenomena
Authors: De Visscher Alex , Boeckx Pascal , Van Cleemput Oswald 
Published: July 2010

AbstractAmmonium (NH+) inhibits the microbial oxidation of methane (CH4), and gives rise to the formation of nitrous oxide (N2O) in aerobic soils. However, the NH+4 concentration in the soil water is not necessarily proportional to the total NH+4 concentration in the soil, due to cation exchange or fixation phenomena. It was found that introducing the concept of ion exchange or fixation in kinetic models on CH4 consumption and N2O formation can increase our knowledge on these processes in soils. A fit of these kinetic models with experimental data showed a standard deviation of slightly more than 10%. The effects of NH+4 on CH4 oxidation and N2O formation can only be compared in soils with the same cation exchange capacity (CEC).
Microbial‐Mediated Reduction of Perchlorate in Groundwater
Authors: Herman David C. , Frankenberger William T. 
Published: July 2010

AbstractPerchlorate has been widely used as a propellant in solid rocket fuel, and has recently been identified as a contaminant in both groundwater and surface waters. Perchlorate is recognized by the U.S. Environmental Protection Agency (USEPA) as a potential health risk, and the State of California has set a drinking water action level of 18 µg L−1. Incidents of groundwater contamination have been associated with industrial sites in California and Nevada that have been involved in the manufacturing or testing of solid rocket propellants. Microorganisms have been shown to be capable of reducing perchlorate (Cl O−4) to chloride (Cl−) and oxygen, thus transforming perchlorate into innocuous end‐products. Bioreactor processes for the remediation of perchlorate contaminated wastewater have previously been established. However, these systems were optimized for perchlorate concentrations in the grams per liter range, while groundwater contamination can be a million‐fold lower but still exceed the water quality action level. This literature review will focus on microbial‐mediated perchlorate reduction, and discuss issues of importance to the remediation of perchlorate‐contaminated groundwater.
Inorganic and Suspended/Dissolved‐Organic Nitrogen in Sierra Nevada Soil Core Leachates
Authors: Marcus J.A. , Miller W.W. , Blank R. R. 
Published: July 2010

AbstractWatershed disturbance has been suggested as a possible mechanism for accelerated nutrient input into Lake Tahoe, California/Nevada. However, little is known regarding how nutrient discharge is coupled to physicochemical watershed processes. Recent investigations in the Lake Tahoe Basin have suggested that suspended/dissolved‐organic nutrient transport may play an important role in lake and tributary water quality. The mobility of inorganic and suspended/dissolved‐organic N in soils of a Lake Tahoe watershed was assessed using constant head permeameter leaching experiments with intact soil cores. We evaluated the interaction of plot condition (riparian, nonforested, and forested) and soil depth (0–15 and 15–30 cm) on magnitude and form of N discharge. Incremental leachate discharge was analyzed for concentrations of inorganic (NH4‐N and NO3‐N) and suspended/dissolved‐organic N. Leachate from the riparian soil cores had significantly higher (P < 0.05) concentrations and total discharge NO3‐N than that from the nonforested or forested areas. Loading of NH4‐N was more consistent among vegetative cover types, but the riparian leachate again contributed a significantly (P < 0.05) greater amount. Suspended/dissolved‐organic N was mobile and the most dominant form of N for nonforested and forested soil cores with discharge loading ratios (suspended/dissolved‐organic:inorganic) of 17:1 and 7:1, respectively. Although the loading ratio was approximately 1:1 for the riparian soil cores, the amount of suspended/dissolved‐organic N discharged was greatest. The mobility and presence of significant amounts of suspended/dissolved‐organic N indicate that this once unrecognized nutrient form is an important component in at least one Sierra Nevada watershed, and should be more fully investigated elsewhere.
Assessment of the Folin and Ciocalteu's Method for Determining Soil Phenolic Carbon
Authors: Ohno Tsutomu , First Paul R. 
Published: July 2010

AbstractPrevious studies have shown that phenolic compounds are potentially allelopathic and present at low concentrations in soil solution. This study was conducted to evaluate the Folin and Ciocalteu's method for determining concentrations of phenolic C in aqueous and citrate extracts of soils containing 7.1 to 57.9 g kg−1 organic C. Soils were reacted for 18 h with a 0.3 mM phenolic acid mixture or DI‐H2O to serve as a control. Folin and Ciocalteu's reactive‐phenolic C content in the DI‐H2O control extracts suggested positive interference from dissolved organic matter rather than free phenolic compounds desorbed from the native soils. The absorptivity of the Folin and Ciocalteu's reduced complex was 1128 ± 25 L mol−1 cm−1 for the phenolic acid mixture and 45 ± 8 L mol−1 cm−1 for soluble organic matter ligands. Although the method has much higher sensitivity to phenolic acids than to organic matter, the higher concentration of organic matter results in substantial background positive interference. However, multiple regression equations of corrected Folin and Ciocalteu's absorbance (phenolic‐treated absorbance minus deionized water control absorbance) regressed with solution parameters had excellent fits (R2 > 0.97). This suggests that interference correction is possible in aqueous extracts. The Folin and Ciocalteu's reactive‐phenolic C concentration in the citrate extracts of the phenolic acid mixture‐amended soils were not significantly different from the DI‐H2O control soil extracts indicating that the Folin and Ciocalteu's method is not suitable for use with soil citrate extractions. The large quantity of organic matter extracted by citrate probably masks absorbance due to any extracted phenolic compounds.
Treatment of Dilute Piggery Effluent with Vertical Flow Reed Beds
Authors: Parkes M. E. , McBride A. D. , Waalkens A. 
Published: July 2010

AbstractWashwater from pig pens was led from a lagoon and treated in a series of vertical flow reed beds over 2 yr. A recirculation component was added in the second yr. Five‐day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), ammonium‐N (NH4‐N), and nitrate‐N (NO3‐N) were measured during the late winter/early spring periods for the 2 yr. Values of KBoD, to describe performance of horizontal flow reed beds, were determined for the vertical flow beds and compared with values derived from the literature. Maximum BOD5 removal was 96%, but averaged 65 and 61% over the first and second year periods, respectively. Performance of each stage, as indicated by percent removal of BOD5, was best described by an inverse logarithmic function of hydraulic load. Ponding was a problem, indicating a need for control of organic loading. Efficient nitrification was not achieved so that the treatment did not result in waste suitable for direct discharge to surface water.
Temperature Effect on Methyl Bromide Volatilization: Permeability of Plastic Cover Films
Authors: Wang Dong , Yates S. R. , Jury W. A. 
Published: July 2010

AbstractConventional methods of applying methyl bromide (MeBr) for soil fumigation can result in significant losses to the atmosphere, potentially contributing to the depletion of stratospheric ozone. It has been found that one of the major factors controlling MeBr volatilization is the permeability of the plastic cover films. Since the most commonly used agricultural film (i.e., polyethylene or PE) is not effective in containing MeBr, one practical method of reducing MeBr volatilization is to replace the PE film with one that is less permeable to MeBr. In this study, we document the temperature‐dependent permeability of standard PE and a new plastic film (Hytibar) that is considered to be virtually impermeable to MeBr. Functional relationships between temperature and the film permeability to MeBr were obtained from a calibration experiment under controlled conditions. A field experiment was conducted to determine MeBr volatilization dynamics from plots covered with the two different plastic films. diffusion‐based transport model was used to simulate the fate and transport of MeBr gas in the soil and volatilization into the atmosphere. In both the calibration and field experiment, the Hytibar film was found to be nearly impermeable to MeBr. Volatilization of MeBr was affected directly by temperature changes of the PE or Hytibar film in the calibration experiment. Under field conditions, MeBr emission was less affected by temperature, especially at large times after application. Model simulation predicted MeBr volatilization reasonably well for the PE covered field plot, but overpredicted the emission for the Hytibar plot.
Potential Sediment Denitrification Rates in Estuaries of Northern Gulf of Mexico
Authors: Flemer David A. , Lores Emile M. , Bundrick Charles M. 
Published: July 2010

AbstractThe three‐season average of sediment potential denitrification rates (PDRs) (i.e., NO−3 saturated; acetylene blockage method) for five study areas within urban bayous and bays in the Pensacola Bay area, Florida, ranged between 43 and 223 nmol of N g−1 h−1. Average PDRs extrapolated to a unit area basis approximated 500 to 1000 µmol of N m−2 h−1 that are relatively high values but comparable to those where conditions for denitrification are favorable. A regression model, based on a larger number of measured environmental factors for the spring than fall and winter indicated that NO−2 + NO−3 concentrations explained most of the total variability (R2: 27%; P < 0.003) in PDRs. The NO−2 + NO−3 concentrations were also predictive of PDRs (R2 ranged from 0.56–0.98; all P‐values <0.05) on four separate occasions for comparisons made within five study areas and three seasons. Sediment trace metal concentrations (e.g., Ni), based on published values, were high enough to cause reduction in PDRs through direct toxicity to denitrifiers at several stations. Sediment metals toxicities, based on published sediment quality guidelines, could occasionally cause a reduction in macrobenthic infaunal bioturbation and irrigation. Such a reduction could attenuate the flux of dissolved oxygen into sediments and cause a reduction in denitrification rates by limiting the coupled processes of nitrification and denitrification. Also, a reduction in the flux of NO−2 or NO−3, a substrate for denitrification, into sediments can directly limit denitrification rates.
The Quantitative Analysis of Sugar Maple Tree Rings by Laser Ablation in Conjunction with ICP‐MS
Authors: Watmough Shaun A. , Hutchinson Thomas C. , Evans R. Douglas 
Published: July 2010

AbstractThis study reports on the quantitative analysis of sugar maple (Acer saccharum Marsh.) tree rings by laser‐ablation ICP‐MS (LAS). Differences in ablation were corrected using 13C as an internal standard. Spatial variation in element distribution within individual tree rings was low, allowing individual tree rings to be used as calibration standards. The relative standard deviation (RSD) for element concentrations within tree rings were 15% for Mg, 15% for Ca, 9% for K, and 16% for Pb. This variation is likely due to element distribution and not the ablation process; the RSD for 13C was <4%. Tree cores were taken from three sugar maple trees adjacent to a major highway, 24 km east of Toronto. Concentrations of Ca, Mg, and K generally declined from pith to cambium, a feature commonly observed in tree boles. Peaks in Pb concentration, between 3 and 5 mg Pb kg−1, were found in tree rings formed between 1940 and 1970, although there was considerable year‐to‐year variation within each tree, and the timing and magnitude of the Pb peaks differed between trees. Lead concentrations decreased in wood formed after 1970 so that by the 1980s, Pb concentrations were around 1 mg kg−1, reflecting changes in Pb deposition into the woodland.
Controls on Fluxes of Trace Gases from Brazilian Cerrado Soils
Authors: Cofman Anderson Iris , Poth Mark A. 
Published: July 2010

AbstractTropical ecosystems play an important role in production or consumption of atmospheric trace gases including nitric oxide (NO), nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4). Here we describe field and laboratory experiments, performed during 1994, to determine the influence of fire on processes responsible for fluxes of gases from cerrado sites burned 17 and 45 d earlier, and a control site, last burned in 1974. Burning stimulated gross N mineralization but depressed nitrification rates; however, rates were sufficient to support NO fluxes observed in a 1992 study at the same site. Extractable nutrients and fluxes of NO and N2O from wetted and dry soils were measured prior to and for a 3‐d period following burning. Over this period NO2− declined to undetectable levels; NH+4 increased, and NO fluxes remained relatively constant, suggesting that nitrifiers replaced the NO2− reduced to NO. Soils at burned and unburned sites exhibited CH4 uptake, which was inhibited by CH3F, thereby converting soils from a strong sink to a weak source of CH4. Carbon dioxide fluxes did not increase, and there were no detectable fluxes of N2O following burning. In lab studies NO and N2O emissions were inhibited by autoclaving, suggesting that nitrification was key to their production. However, addition of NO2− to autoclaved soil resulted in large fluxes of NO but no detectable N2O, suggesting that chemodenitrification may have been responsible for NO but not N2O production. Further research is needed to determine whether NO is produced directly by nitrifier NO2− reduction or indirectly by chemodenitrification of NO2− produced by nitrifiers.
Selenium Uptake by Plants from Soils Amended with Inorganic and Organic Materials
Authors: Ajwa H. A. , Bañuelos G. S. , Mayland H. F. 
Published: July 2010

AbstractDepending on its concentration and chemical form, Se functions as an essential element or potential toxicant to humans, livestock, and waterfowl. Application of seleniferous organic materials to soils may increase plant‐available Se content and pose health hazards. This study assessed Se uptake by two successive plantings of canola (Brassica napus cv. Westar) and multiple clippings of tall fescue (Festuca arundinacea L. cv. Fawn) grown in soils [Hanford sandy loam (coarse‐loamy, mixed, thermic Typic Durixeralfs) and Panoche clay loam (fine‐loamy, mixed, superactive, thermic Typic Torriorthents)] amended with 1.5 mg Se kg−1 soil as inorganic selenate (Se O42−) or seleniferous organic materials [alfalfa (Medicago sativa L.), Astragalus praelongus, or cattle (Bos tauris) manure] under growth chamber conditions. Tissues of canola and tall fescue accumulated much greater concentrations of Se from the inorganic SeO42− treatment compared to the treatments with seleniferous organic materials. The addition of crop residue or animal manure to the SeO42−‐treated soils considerably reduced Se accumulation by both plant species. In soils amended with seleniferous organic materials, more than 80% of the Se remained in soils after two plantings of canola and all clippings of tall fescue. The slow release of plant‐available Se in soils amended with seleniferous organic materials suggests the use of these materials to control the concentrations of Se in crops grown on nonseleniferous soils.
Sewage Sludge and Mycorrhizal Effects on Secar Bluebunch Wheatgrass in Mine Spoil
Authors: Thorne M. E. , Zamora B. A. , Kennedy A. C. 
Published: July 2010

AbstractEstablishing vegetation on mine spoil often requires amendments to supply nutrients and microorganisms to re‐establish attributes associated with developed soil. Arbuscular‐mycorrhizal fungi (AMF) and composted sewage sludge (CSS) were evaluated as possible minespoil amendments to create a topsoil substitute for revegetation of the Midnite Mine, Stevens County, Washington. Most original topsoil was buried and existing spoil is low in nutrients and organic matter and not capable of supporting desired vegetation. Secar bluebunch wheatgrass [Pseudoroegneria spicata (Pursh) A. Love × Elymus lanceolatus ssp. lanceolatus (Scribn. & J.G. Sm.) Gould] was grown in nonsterile spoil amended with 0.0, 6.2, 12.4, 24.5, and 49.0 g dry CSS per liter of spoil‐sand mix for 16 wk in a glasshouse experiment. Arbuscular‐mycorrhizal fungi treatments were spores of Glomus mosseae [(Nicol. & Gerd.) Gerdemann & Trappe] collected from native bluebunch wheatgrass plants, non‐native spores of Glomus intraradices (Schenck & Smith) and Entrophaspora sp. (Ames & Schneider), or no added spores. In addition, Secar was grown in nonsterile, stockpiled topsoil with both AMF treatments to compare to AMF present in the topsoil. Each CSS rate increase produced increased above‐ground and belowground plant growth. Secar growth was enhanced by native AMF in CSS‐amended spoil. Composted sewage sludge appeared to reduce AMF colonization; however, hyphae levels in plants with native AMF were unaffected. Plant growth was not affected by AMF treatments in stockpiled topsoil but AMF colonization was greater in plants with the topsoil alone. Benefits from CSS and selection of an effective AMF culture are evident.
Mineralization of Norflurazon in a Cranberry Bog Soil: Laboratory Evaluations of Management Practices
Authors: Savin Mary C. , Amador José A. 
Published: July 2010

AbstractNorflurazon (4‐cldoro‐5‐(methylamino)‐2‐(α,α,α‐trifluoro‐m‐tolyl‐3(2H)‐pyridazinone) is a pre‐emergent herbicide used in cranberry (Vaccinium macrocarpon Air.) cultivation to control annual grasses, sedges, and broadleaf weeds. Cranberries are an economically important crop in New England, Wisconsin, and other parts of the northern USA. The biodegradation of norflurazon in the high organic matter, acidic soil characteristic of cranberry bogs has been shown to proceed slowly (Savin and Amador, 1998). The potential effects of cranberry cultivation practices—soil moisture control, fertilization, sand addition, and herbicide application rate—on mineralization of norflurazon in a bog soil were evaluated in a laboratory study. Optimal soil moisture for norflurazon mineralization was between 80 and 90% of water‐holding capacity (WHC) in soil from the Oi and A horizons. Saturating the soil reduced the rate of norflurazon mineralization significantly. By contrast, soil respiration was maximal at 25% of WHC in both horizons. Addition of inorganic P increased soil respiration, but did not affect norflurazon mineralization significantly. Addition of inorganic N plus P increased soil respiration in the A, but not Oi, horizon and significantly decreased norflurazon mineralization in the Oi horizon. Sand addition had no significant effect on norflurazon mineralization. Mineralization was affected by herbicide application rate, with the rate of mineralization increasing proportionally with increasing concentration from 0.75 to 7.5 mg norflurazon kg−1 soil. The mineralization of 14C‐norflurazon was slow for all of the agronomic practices evaluated, indicating that the potential for norflurazon to accumulate in cranberry bog soils may be high.
Decreases in Soil Microbial Function and Functional Diversity in Response to Depleted Uranium
Authors: Meyer Michael C. , Paschke Mark W. , McLendon Terry , Price David 
Published: July 2010

AbstractA soil microcosm experiment was used to analyze effects of depleted uranium (DU) on soil function, and the concomitant changes in bacterial functional diversity. Uranium treatment levels were 0, 50, 500, 5000, 10 000, and 25 000 mg DU kg−1 soil. Three measures of soil function were made. Overall soil biological activity was assessed via measurement of soil respiration. Decomposition was assessed by measurement of mass loss of four different plant litter types: wood sticks, cellulose paper, high‐N grass, and low‐N grass. Mineral N availability in the microcosms was estimated using ion‐exchange resin bags. Functional diversity of the microcosms was analyzed through the use of the Biolog‐system of sole‐C‐utilization patterns. Soil respiration was the most sensitive measure of functional changes, with significant decreases observed starting at the 500 mg kg−1 treatment. No differences in N availability were observed across the U treatments. Litter decomposition was significantly decreased (P < 0.05) at the 25 000 mg kg−1 level relative to the control for all litter types except the high‐N grass. Wood decomposition was reduced by 84% at the 25 000 mg kg−1 treatment, cellulose paper by 68%, and low‐N grass by 15%. Decreases in the functional diversity of the bacterial community were related to the observed decrease in soil respiration, and to the greater effect on decomposition of the lower‐quality litter types.
Atrazine Interactions with Soil Humic Substances of Different Molecular Structure
Authors: Piccolo Alessandro , Conte Pellegrino , Scheunert Irene , Paci Maurizio 
Published: July 2010

AbstractThe mode of atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] adsorption to humic substances is still uncertain, mainly because of the large heterogeneity of humus and its poor molecular characterization. In this study, four humic fractions were isolated from a peat and a volcanic soil by three different extraction mechanisms: charge repulsion (NaOH extraction), ligand exchange (pyrophosphate extraction, Na4P2O7), and hydrogen‐bonding disruption (extractions by aqueous mixture of acetone and dymethyl sulphoxide, DMSO). These four humic fractions showed consistent differences in molecular structure between the two soils. Humic fractions extracted by acetone had the largest content of aliphatic C, whereas those obtained by the pyrophosphate solution were richest in aromatic C. Sorption isotherms of 14C‐labeled atrazine conducted on the four humic fractions showed that, for both soils, the order of adsorption was acetone > NaOH > DMSO > Na4P2O7, whereas the order for desorption was the reverse. The relation between results of atrazine interaction and the molecular structure of humic matter indicates that the aliphatic C content of soil organic matter may be one of the parameters controlling atrazine adsorption to soils. Hydrophobic interactions and conformational flexibility in the aliphatic portions of humic matter controlled the adsorption of atrazine in the interior of humic self‐associated aggregates and the degree of desorption found both in water and methanol. Conversely, the conformational rigidity conferred to humic fractions by a large content of aromatic moieties appeared conducive only to surface adsorption and thus to easier herbicide desorption.