bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sorption of Polychlorobiphenyl (PCB) Congeners by Residual PCB‐Oil Phases in Soils
Authors: Sun Shaobai , Boyd Stephen A. 
Published: July 2010

AbstractIn this report we show that residual polychlorobiphenyl (PCB) oil present in soils heavily contaminated with PCB mixtures (Aroclors) functions as a highly effective partitioning medium accounting for the sorptive uptake of 2‐chlorobiphenyl from water. A PCB‐oil normalized partition coefficient (KPCB) was evaluated from the experimental sorption data of 2‐chlorobiphenyl onto four PCB‐oil contaminated soils which had PCB‐oil contents ranging from 2.17 g/kg to 7.67 g/kg (2170 ppm‐7670 ppm). This KPCB value (114 000) indicates that the residual PCB‐oil phase in soils, as a partitioning medium for 2‐chlorobiphenyl, is approximately 67 times more effective per unit mass than natural soil organic matter (KOM = 1700) and 3.5 times more effective than octanol (KOW = 32 400). Our results suggest a threshold PCB concentration in soil of about 0.1% (w/w), above which the PCB mixture forms a separate sorptive phase. The threshold concentration may correspond to the solubility of the liquid PCB mixture in natural soil organic matter. Because of its greater surptive effectiveness, the PCB‐oil phase, once formed, will primarily determine the soil‐water distribution of individual PCB congeners. Accurate prediction of the soil‐water distribution of PCB congeners in such soils can be obtained by considering the additive sorptive effects of the anthropogenic and natural organic matter phases.
Design and Performance of Branch Chambers Suitable for Long‐Term Ozone Fumigation of Foliage in Large Trees
Authors: Teskey R. O. , Dougherty P. M. , Wiselogel A. E. 
Published: July 2010

AbstractFumigation chambers for exposing branches of mature trees to ozone (O3) were developed and used in a 2‐yr field study. The performance compared very favorably with that of open‐top chambers. The branch chambers were cylindrical, with dimensions of 1.5 by 0.5 m. To examine the effects that the chamber alone might have on branch or foliage physiology and phenology, six chambers were placed on the branches of trees that had no additional treatments (i.e., no charcoal filtration or O3 amendments). These chambers produced no significant effects on the growth of the branches or foliage within them, as compared with adjacent, nonchambered branches. Hourly net photosynthetic rates were also very similar. The air in the chambers was exchanged 10 times per minute, which resulted in nearly identical air temperatures, relative humidities, and CO2 concentrations inside and outside the chambers. Only light levels were significantly lower within the chambers, which was due primarily to the light transmission properties of the PVC plastic covering the chambers. This approach allows long‐term fumigations to be made on mature tissue of large trees, providing an alternative to the use of seedlings in studies of the effects of O3 or other gases on forest species.
Sorbed Chemical Transport in Overland Flow: I. A Nutrient and Pesticide Enrichment Mechanism
Authors: Ghadiri H. , Rose C. W. 
Published: July 2010

AbstractMechanisms of sediment detachment by rainfall and transport by runoff were studied to seek explanation for the enrichment of sorbed chemicals in eroded sediment compared with the original soil. Experiments were carried out in which the outer coats of structurally stable aggregates were peeled away and the peeled material and inner core analyzed separately for chemical concentrations. Results showed that the material removed from the outer layers of the aggregate had higher concentrations than the inner core of organic matter, N, and six different sorbed pesticides. Aggregates of the same soil were exposed in a flume to constant‐rate simulated rainfall for two periods of 30 and 50 min. As a result of such exposure, the concentration of N, organic matter, and pesticides decreased for large aggregates and increased for finer particles. It appears that upon impact, raindrops not capable of totally breaking down stable aggregates remove their outer coat, converting it into fine particles that are richer in sorbed chemicals than any size fraction, including those of similar size in the original soil. This generation of fine particles by the peeling action of raindrops yields eroded sediment with finer size characteristics than the original soil. Thus, the hypothesis examined in this article is that the differential concentration of sorbed chemicals within the soil aggregate, coupled with the peeling action of raindrops, is one reason why eroded sediment is finer and richer in sorbed chemicals than the soil from which it originates. This hypothesis was supported by the results of both peeling and flume experiments carried out in this study. Provided raindrop impact does not lead to the total collapse of aggregates, stripping by raindrops can be the major cause of chemical enrichment in the eroded sediment.
Development of a Database and Model Parameter Analysis System for Agricultural Soils
Authors: Carsel Robert F. , Imhoff John C. , Kittle John L. , Hummel Paul R. 
Published: July 2010

AbstractAn interactive computer program was developed for obtaining soils data for geographic analyses and estimation of soil water retention data for simplistic and classical water flow models. The soils data base contains 8080 soil series identified from the USDA‐SCS. The data are organized in sequential files that contain textural, morphological, crop support, and geographical location (at a county level) and density (ha/county). The computer program allows the exploration of the database, clarifying the impact of data on modeled processes, screening geographically based data to identify potential sits for model application or testing, and developing initial guidance on alternative water quality management strategies. The program allows the display of data in the form of generated reports and production of geographic maps and plots of soil water functional reintionships. Indirect methods are used in the program for estimating soil water retention characteristics using textural information from the soil data base. Estimates of variability can be developed within a soil series or among series by using reported ranges for textural information on each series contained in the soil database.
Soil Microbial Activity at High Levels of Carbon Monoxide
Authors: Hendrickson O. Q. , Kubiseski T. 
Published: July 2010

AbstractSoils are an important sink for atmospheric carbon monoxide (CO) via microbial uptake. In this study, the disappearance of CO during a 24‐h period was used to quantify potential CO uptake rates (Vmax) for various soils and treatments. When 2.0 kPa CO was added to the gas phase above forest soil, amounts of this gas declined linearly for 24 h, suggesting a zero‐order or saturated reaction. Amounts of CO remained constant over autoclaved soil. Rates for forest, lawn, and garden soils ranged from 0.56 to 7.41, 0.39 to 0.80, and 0.17 to 0.19 mg CO‐C kg−1 dry soil h−1, respectively. Ability of roadside soil to consume CO was significantly reduced by a 19‐d incubation at ambient CO levels, but was increased tenfold by repeated exposures to 2 kPa CO. This positive effect of long‐term CO exposure indicated that autotrophic organisms (carboxydobacteria) were active in roadside soil, but did not exclude the presence of heterotrophic organisms, which oxidize CO by cometabolic processes. A strong relationship between CO consumption and soil organic matter content or soil respiration suggested that high potential rates of soil CO consumption in unpolluted environments may reflect microbial exposure to endogenous CO arising from abiotic oxidation of soil C compounds. Forest soils with intact surface organic horizons may be particularly active CO sinks.
Reclamation Effects on Mycorrhizae and Productive Capacity of Flue Gas Desulfurization Sludge
Authors: Wilson G. W. T. , Hetrick B. A. D. , Schwab A. P. 
Published: July 2010

AbstractTen years after portions of a dewatered flue‐gas desulfurization sludge pond has been reclaimed by seeding and fertilizing, the productive capacity of reclaimed sites was higher than abandoned sites. Mycorrhizal symbiosis may be partly responsible for the increased productive capacity of the reclaimed sites, as indicated by the observation that the reclaimed sites had 2.4 times the number of mycorrhizal spores, 5.1 times the root colonization, and 2.2 to 28 times the inoculum potential of the abandoned sludge. In reclaimed sludge, 82 to 100% of all plants became mycorrhizal compared with 30 to 67% of plants in abandoned sludge. Through regression analysis, it was predicted that the reclaimed sludge sites would have a greater productive capacity than the abandoned sludge sites, even if all plants were mycorrhizal. To determine whether these differences in productive capacity were caused by differences in inoculum level, ecotypic variation in inocula, or host plant adaptation to the indigenous inoculum, inocula from an undisturbed soil, pot culture, and the sludges were compared on five host plants grown in the sludges and a prairie soil. While host, soil, and mycorrhizal status (with or withouot mycorrhizae) did affect herbage yield, inoculum source did not. In undisturbed soil, reclaimed sludge, and abandoned sludge, mycorrhizal C3 plants were 7, 71, and 90% larger, and C4 plants were 1300, 1100, and 600%6 larger than nonmycorrhizal plants, respectively. These studies demonstrate that reclamatio6n efforts stimulate recovery and productive capacity of disturbed sites, and that mycorrhizal symbiosis is an integral component in site recovery from disturbance.
Influence of pH, Sodium Adsorption Ratio, and Salt Concentration on Settling Kinetics of Suspended Solids in Coal‐Mine Ponds
Authors: Evangelou V. P. , Karathanasis A.D. 
Published: July 2010

AbstractColloidal particle‐settling experiments were conducted in the laboratory to test the influence of pH and dissolved solids on the kinetics of settling of suspended solids in a coal‐mine spoil sample obtained from western Kentucky. Potentiometric titrations suggested that the pH range of colloid coflocculation for the sample tested was around 4.2. Repulsive diffuse double layers at pH above 4.2 appeared to control‐suspended solid behavior. The rate of settling of suspended solids decreased as the pH of the suspension increased. This rate was highly influenced by the ionic strength, sodium adsorption ratio (SAR) and type of divalent cation (Ca or Mg). With Ca as the saturating cation and SAR values below 1, the suspended solids dropped below the required 35 mg/L limit within a 2–h period. At SAR values above 4 and pH near and/or above 7 suspended solids exceeded those required by law. When the divalent cation was Mg, the coal‐mine spoil solids appeared to be less dispersive. For sedimentation ponds neutralized with NaOH, this type of kinetic information is necessary to improve sediment trapping efficiency and design ponds with appropriate water detention times.
Acid‐Base Chemistry of Dissolved Organic Matter in Aqueous Leaf Extracts: Application to Organic Acids in Throughfall
Authors: Brown Aaron D. , Sposito Garrison 
Published: July 2010

AbstractElemental composition data were obtained for bulk precipitation and throughfall samples and for aqueous extracts of the leaves 6of three woody plant species common in the subalpine Sierra Nevada range, California: chinquapin (Chrysolepis sempervirens Hjelmqvist), western white pine (Pinus monticola Dougl.), and willow (Salix orestera Schneider). The acid‐base equilibria of the extracts were characterized by potentiometric titration and proton formation functions were computed. The latter then were modeled assuming four classes of quasiparticle acidic functional groups, yielding negative logarithms of conditional protonation constants in the range 4.8 to 5.0, 6.1 to 6.6, 7.4 to 7.7, and 9.1 to 9.4. The relative concentration of a given acidic functional group class varied markedly among the three woody species, but the conditional protonation constants were very similar. The model parameters, along with dissolved organic C concentration and pH values, were used to estimate net anion deficits in throughfall samples collected from the same sites as the leaf samples. On average, the calculated charge concentration of free organic anions in the western white pine extract matched the throughfall anion deficit, whereas the deficits in the chinquapin and willow throughfall samples were not accounted for by free anion concentrations. Metal complexation and in situ, species‐dependent leaf surface processes may account for these latter differences. In general, the anion deficit and, therefore, organic acids were an important component of rainfall and throughfall charge balance.
Microbial Populations in an Agronomically Managed Mollisol Treated with Simulated Acid Rain
Authors: Miller Kathleen W. , Cole Michael A. , Banwart Wayne L. 
Published: July 2010

AbstractA fertile well‐buffered mollisol (Flanagan silt loam, fine montmorillonitic mesic Aquic Argiudoll) under cultivation with corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] was subjected to simulated rain of pH 5.6, 4.2, and 3.0, while moisture‐activated rain exclusion shelters provided protection from ambient rain. Soil was sampled to a depth of 3 cm on four dates throughout the 1985 growing season. The following microorganisms were enumerated by plate counts or most probable number: general heterotrophic bacteria, general soil fungi, free‐living N‐fixing bacteria, fluorescent pseudomonads, autotrophic ammonium‐oxidizing, nitrite‐oxidizing, and thiosulfate‐oxidizing bacteria. The ANOVA was used to determine the combined and individual effects of rain treatments, crop field, and sampling date. Crop field and sampling date affected microbial numbers more than rain treatments. Overall, rain treatment effects were limited to nitrite‐oxidizing bacteria; lower numbers occurred in the corn field in subplots treated with rain of pH 4.2 and 3.0, and in the soybean field treated with rain of pH 3.0. The trend was strongest in June and July. In the corn field in subplots treated with rain of pH 3.0, numbers of thiosulfate‐oxidizing bacteria were higher and numbers of general heterotrophic bacteria were lower; however, these trends were comparatively weak. Rain treatments caused essentially no decrease in soil pH, suggesting that acid rain constituents affect certain microbial populations without causing overt changes in pH. Because they appear to be unusually sensitive, nitrite‐oxidizing bacteria could be used as experimental indicators of changes in soil microbial communities subjected to acid rain.
Phosphorus and Nitrogen Export from Forested Stream Catchments in Central Ontario
Authors: Dillon P. J. , Molot L. A. , Scheider W. A. 
Published: July 2010

AbstractThe ability to predict export of algal nutrients from forested stream catchments is essential to estimate background levels of nutrients in lakes and therefore gauge the effects of anthropogenic activities on the trophic status of Ontario lakes. Data from 32 forested stream catchments in the Muskoka‐Haliburton area of central Ontario collected during the 8‐yr period 1976–1977 to 1983–1984 were used to develop empirical regression models of long‐term average NH4, NO–3, TON, and TP export employing mathematical transformations of geology, physiography, hydrology, and annual meteorological data. At least 6 consecutive years of sampling were necessary to avoid poor fits due to anomalous years and to produce regression models able to make reliable (R2 > 0.70) long‐term average predictions of TP export. Atmospheric deposition of algal nutrients typically exceeded catchment export. Total annual phosphorus (TP) export was variable with outputs from two catchments exceeding atmospheric inputs. Total organic nitrogen (TON) export was also variable with annual export from 22 catchments exceeding atmospheric inputs, although total N (TN) export never exceeded input. Peat deposits or beaver (Castor canadensis Kuhl) ponds in most of these catchments were the likely sources of the high TP and TON export. Nitrate retention (defined as the fraction of annual deposition retained by the catchment) was high in most catchments, exceeding 0.74 in 26 of the 32 catchments. Low NO–3 retention was observed primarily in those catchments with steep grades (>5.9%). Ammonium retention was very high (>0.87) in all catchments.
Phosphorus Geochemistry in the Sediment‐Water Column of a Hypereutrophic Lake
Authors: Moore P. A. , Reddy K. R. , Graetz D.A. 
Published: July 2010

AbstractThe role of sediment biogeochemistry on diffusive flux of inorganic P was examined under laboratory conditions using intact sediment cores obtained from a subtropical hypereutrophic lake. The effect of light and dark conditions in the water column on soluble P flux from sediments was measured over a period of 1 yr. Soluble reactive P (SRP) level in the overlying water column was low (<0.01 mg P L–1) under light conditions, while values under dark conditions steadily increased. This suggests algal uptake under light conditions. Diffusive flux of soluble P from sediments as calculated by measuring the increase in concentration of the overlying water in the dark was 2.71 mg P m–2 d–1. Flux of this magnitude could increase lake water SRP levels by approximately 0.5 mg P L–1 yr–1. Soluble reactive P concentrations were roughly equivalent to dissolved P concentrations, both for the water column and for the sediment porewater. Porewater SRP increased with depth to a maximum of 6.0 mg P L–1 at 40 cm. Phosphorus flux as calculated from prewater SRP gradients averaged 1.69 mg P m–2 d–1. Sediment P fractionation indicated that water soluble P, KCl extractable P, and Fe and Al‐bound P decreased with depth, whereas the amount of Ca‐bound P increased. Calcium‐bound P was the dominant fraction, comprising over 50% of the total P content. Ion activity products (IAP) calculated using GEOCHEM indicated that the sediments were supersaturated with respect to apatite, beta tricalcium phosphate and whitlockite, with the latter expected to be the phase controlling PO–34 activities.
The Transport of Bioavailable Phosphorus in Agricultural Runoff
Authors: Sharpley Andrew N. , Smith S.J. , Jones O.R. , Berg W.A. , Coleman G.A. 
Published: July 2010

AbstractBioavailable P (BAP) in agricultural runoff represents P potentially available for algal uptake and consists of soluble P (SP) and a variable portion of participate P (PP). Evaluation of the impact of agricultural management on BAP in runoff will aid assessment of the resultant biological productivity of receiving water bodies. Soluble P, PP, and bioavailable PP (BPP) (estimated by NaOH extraction) were determined over a 5‐yr period in runoff from 20 unfertilized and fertilized, grassed, and cropped watersheds in the Southern Plains. Soluble P, BPP, and BAP loss in runoff was reduced by practices minimizing erosion and runoff, with respective mean annual amounts ranging from 237 to 122, 1559 to 54, and 1796 to 176 g P ha−1 yr−1 (for peanut‐sorghum [Arachis hypogaea L.‐Sorghum bicolor (L.) Moench] and native grass watersheds, respectively). However, as vegetative cover improved, BAP (SP plus BPP) comprised a larger portion of total P (TP) loss (29% for peanut‐sorghum and 88% for native grass). This results from an increasing contribution to BAP of SP (13% for peanut‐sorghum and 69% for native grass watersheds) and BPP to PP (26% for peanut‐sorghum and 69% for native grass watersheds). Clearly, P bioavailability is a dynamic function of physiochemical processes controlling erosion, particle size enrichment, P desorption‐dissolution reactions, and plant residue breakdown, in addition to soil and fertilizer P management. Hence, the change in trophic state of a water body may not be adequately reflected by TP inputs only. To more reliably evaluate the biological response of a water body to agricultural P inputs, particularly from conservation tillage practices, it may be necessary to determine BAP in runoff.
Effect of Surface Application of Polyvinyl Alcohol on Phosphorus Losses in Runoff and on Corn Growth
Authors: Marsh M.H. , Groenevelt P.H. 
Published: July 2010

AbstractPhosphorus loading in surface water bodies due to runoff from cropland is a major concern with respect to water quality. Losses of water, soil, and different forms of P, from five runoff plots treated with polyvinyl alcohol (PVA), were comparet do losses from five untreated plots. The plots were on a loam soil with 6.5 to 9.5% slopes. The effect of a single application of PVA was observed over 2 yr under natural rainfall. During the first year after application of PVA, runoff and soil losses were reduced by 56 and 80%, respectively. Extractable P, total P, and dissolved molybdate‐reactive P (DMRP) losses were reduced by 79, 75, and 64%, respectively. Corn (Zea mays L.) grain yield on the treated plots was 12% higher than on the control plots. All the above differences were statistically significant. During the second year, in which no tillage occurred and no PVA was applied, total P and DMRP losses were reduced by 42 and 40%, respectively, by the PVA treatment of the previous year. Although runoff and soil loss were lower for the treated plots, these differences were not significant at P = 0.05 (P values were 0.11 and 0.10, respectively.
Vegetative Filter Treatment of Dairy Barnyard Runoff in Cold Regions
Authors: Schellinger G. R. , Clausen J. C. 
Published: July 2010

AbstractA vegetative filter strip was installed to treat barnyard runoff from an active dairy farm in Vermont. Runoff from a concrete surfaced barnyard flowed through a detention pond, then onto a vegetative filter strip measuring 22.9 m by 7.6 m with a 2% slope. The water input and surface and subsurface outputs for the strip were continuously monitored from December 1984 through May 1986. Of the total barnyard runoff entering the strip, 65% left as surface runoff and 27% was measured as subsurface outflow. The average hydraulic loading rate was 14.7 cm wk−1 and the average overland flow detention time was 15 min. The filter strip did not significantly (P < 0.05) reduce solids, P, N and bacteria concentrations in the surface output. Over the period of study the mass retention was 33% total suspended solids, 12% total P and 18% total Kjeldahl N. Mass retention was highest during the growing season and was poorest during snowmelt periods. It was concluded that poor filter strip performance was due to an excessive hydraulic loading rate resulting in an inadequate detention time for proper treatment. A preferential flow path from the level lip spreader to the subsurface drain tiles may have contributed to the poor subsurface treatment performance.
Nitrogen Fixation in Soybean Treated with Nitrogen Dioxide and Molybdenum
Authors: Gupta Gian , Narayanan Radhika 
Published: July 2010

AbstractSoybean plants were treated with Mo (0.0 or 2.0 mg kg−1, soil dry wt.) and exposed to NO2 (0.0, 0.05, or 0.1 µmol mol−1) at flowering stage. Specific root nodule activity (SNA), chlorophyll‐a (Ch‐a), chlorophyll‐b (Ch‐b), leaf N, number of pods, seeds per pod, weight of seeds, and shoot dry weight were measured. Compared with control, SNA did not change on the addition of 2 mg Mo to the soil, but increased by 65% on exposure to 0.1 µmol mol−1 NO2 and by 106% on treatment with both NO2 and Mo. Both Ch‐a and Ch‐b increased significantly on exposure to 0.1 µmol mol−1 NO2 and the amount of this increase with 0.05 µmol mol−1 NO2 and 2 mg MO was almost the same as with 0.1 µmol mol−1 NO2 alone. Leaf‐N increased by 46% on exposure to NO2 but did not change on the addition of Mo. Pod number, seed number and weight, and shoot dry weights showed significantly higher values on exposure to 0.1 µmol mol−1 NO2 and 2 mg Mo.