bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nutrient Cycling in Forests of Walker Branch Watershed, Tennessee: Roles of Uptake and Leaching in Causing Soil Changes
Authors: Johnson D. W. , Todd D. E. 
Published: July 2010

AbstractPrevious studies showed that subsoil exchangeable Ca2+ and Mg2+ decreased over the period 1971 to 1982 in several plots on Walker Branch Watershed. It was hypothesized that wood accumulation (i.e., uptake and sequestering in both living and dead tree biomass) was the dominant cause of the exchangeable Ca2+ decreases, whereas atmospheric deposition‐induced leaching was the dominant cause of the exchangeable Mg2+ decreases. As hypothesized, wood accumulation far exceeded leaching of Ca2+ in those plots where soil exchangeable Ca2+ decreased. The hypothesis regarding causes of exchangeable Mg2+ decrease was neither accepted nor rejected from the data on hand. Leaching exceeded wood accumulation of Mg2+ in three of the four plots studied (pine, Pinus; yellow‐poplar, Liriodendron tulipifera; and chestnut oak Quercus prinus). Cation leaching in these three plots was balanced by SO2−4, and input‐output balances indicated that soil solution SO2−4 originated primarily from atmospheric deposition. Thus, the trends toward decreased subsoil exchangeable Mg2+ in those particular plots (while not all statistically significant at the 95% level), are attributable primarily to atmospheric S deposition. However, leaching was minimal in the fourth plot (oak hickory, Quercus‐Carya spp.) due to very low soil solution SO2−4 concentrations, yet subsoil Mg2+ decreases were significant at the 95% level. In the latter case, wood uptake was the dominant mechanism of Mg2+ removal from the soil. The importance of slope position in determining nutrient cycling patterns and the long‐term changes in nutrient status is also discussed.
Runoff of Sulfometuron‐Methyl and Cyanazine from Small Plots: Effects of Formulation and Grass Cover
Authors: Wauchope R. Don , Williams Randall G. , Marti Luz. R. 
Published: July 2010

AbstractTo determine the effects of application rates, grass cover, and formulation type on herbicide losses in runoff, we applied 4.5 kg/ha cyanazine (2‐[(4‐chloro‐6‐(ethylamino)‐1,3,5‐triazin‐2‐yl)] amino]‐2‐methylpropanenitrile) with 0.4 kg/ha sulfometuron‐methyl (methyl‐2[[[[(4,6‐dimethyl‐2‐pyrimidinyl)amino] carbonyl] amino] sulfonyl] benzoate) to 1.2 by 2.4 m plots, using suspension concentrate (SC) and dispersible granule (DG) formulations of cyanazine, and SC and emulsifiable concentrate (EC) formulations of sulfometuron‐methyl. The plots were established on a Tifton loamy sand soil (fine‐loamy, siliceous, thermic Plinthic Paleudults) and had 3% slope. The plots were bare or covered with a mixed stand of common Bermudagrass [Cynodon dactylon (L.) Pers.] and Bahiagrass (Paspalum notatum Flugge var. suarae Parodi). On the day after the herbicides were applied, we simulated rainfall events of 69 mm/h intensity until 2 mm of runoff occurred. The runoff was analyzed for sediment and herbicides. The bare plots required one‐third less rain to produce the same amount of runoff and yielded twice as much sediment as the grassy plots. However, losses of all formulations were 1 to 2% of the amounts applied regardless of grass cover and even though cyanazine rates were 11 times that of sulfometuronmethyl. Total losses of all formulations were sensitive to the length of time between rainfall initiation and runoff initiation, indicating that leaching made herbicide unavailable for runoff. These results suggest that, for these formulations under conditions of similar runoff volumes, losses of pesticides are a fairly constant fraction of the amounts applied, with or without grass cover. For intense storms where the amount of rainfall is similar, chemical runoff from the grassed plots was predicted by computer simulation to be less than half of that from bare soil.
Nitrate‐Nitrogen Concentrations in Percolate from Lysimeters Planted to a Legume‐Grass Mixture
Authors: Owens L. B. 
Published: July 2010

AbstractGrowing concern that N from agricultural sources is a major pollutant of groundwater has stimulated research on NO3‐N concentrations in groundwater under crops receiving N fertilizer. Knowledge of the effects of legumes on groundwater quality and their potential for reducing NO3‐N concentrations is limited. Three Coshocton monolith lysimeters (Y‐102A, B, and C) containing a well‐drained silt loam soil on a 13% slope, and four lysimeters (Y103A, B, C, and D) containing a moderately well‐drained silt loam soil on a 6% slope were used to study the effects of a legume‐grass mixture on groundwater quality. Between experiments with corn (Zea mays L.), an alfalfa‐orchard grass mix (70% Medicago sativa L. + 30% Dactylis glomerata L.), was grown for 2 yr and 3 yr on the Y102 and Y103 lysimeters respectively. The corn, some of which received high rates of N fertilizer, produced NO3‐N concentrations in percolate ranging from 15 to 40 mg/L. Under alfalfa, NO3‐N concentrations in leachate often were less than 5 mg/L, especially on the moderately well‐drained lysimeters. The highest NO3‐N percolate concentrations under all treatments occurred during the winter/early spring months.
Oxygen Transport through Aquatic Macrophytes: The Role in Wastewater Treatment
Authors: Reddy K. R. , D'Angelo E. M. , DeBusk T. A. 
Published: July 2010

AbstractLaboratory experiments were conducted to determine the effectiveness of three floating and six emergent aquatic macrophytes in improving domestic wastewater quality, based on their capacities for O2 transport into the effluent. Oxygen transport into the rooting zone of the plants created an oxidized microenvironment, thereby stimulating C and N transformations critical to wastewater treatment. Plants were cultured in flasks containing deoxygenated primary and secondary sewage effluent for an 8‐d period. Oxygen transport by the plants was measured in terms of both O2 consumed by the effluent (biological O2 demand reduction—BOD5) and increased effluent dissolved O2. Two floating plants, pennywort (Hydrocotyle umbellata L.) and waterhyacinth [Eichhornia crassipes (Mart.) Solms], and the emergent plants pickerelweed (Pontederia cordata L.) and common arrowhead (Sagittaria latifolia L.), were superior in improving primary sewage effluent quality, by reducing BOD5 up to 88%, NH4‐N up to 77%, and increasing dissolved O2 up to 6.1 mg L−1. Nitrification rates in pennywort‐ and water hyacinth‐based water treatment systems were calculated to be in the range of 12 to 47 kg NH4‐N ha−1 d−1. Oxygen transport through plants accounted for up to 90% of the total O2 transported into the effluent. In separate batch experiments, the effectiveness of diffuse mechanical aeration (5 and 50 mL air min−1) and of biological aeration (O2 transport by selected plants including pennywort, waterhyacinth, pickerelweed, and common arrowhead) on the rate of contaminant removal from deoxygenated primary sewage effluent were compared for a 26‐d period. Biological and mechanical aeration effected similar BOD5 removal. First‐order reaction rate constants for BOD5 removal were from 0.0066 to 0.0079 h−1 and from 0.0041 to 0.0051 h−1 for biological and mechanical aeration, respectively. Rate constants for NH4‐N removal were from 0.0024 to 0.0107 h−1 for the plant treatments. Virtually complete BOD5 removal occurred in biological and mechanical aeration treatments within 20 d. Complete nitrification of NH4‐N had occurred within 12 d after mechanical aeration was initiated, but subsequent N‐loss by denitrification was inhibited. In the biological aeration treatments, negligible effluent (NO3 + NO2)‐N levels were measured, but 65 to 100% NH4‐N loss occurred both by plant assimilation and by sequential nitrification‐denitrification reactions.
Processes of Iron and Manganese Retention in Laboratory Peat Microcosms Subjected to Acid Mine Drainage
Authors: Henrot Jacqueline , Wieder R. Kelman 
Published: July 2010

AbstractDespite increasing use of constructed wetlands for treatment of metal‐enriched acid coal mine drainage (AMD), the biotic and abiotic mechanisms of metal retention in such wetlands are poorly understood. The present study was conducted to evaluate the processes responsible for Fe and Mn retention in peat and the effects of microbial activity, pH, temperature, and metal concentration in AMD on these processes. Experimental units consisted in 30 g (wet wt.) of fresh Sphagnum peat, which was repeatedly flushed with synthetic AMD at pH 3.5. Of the four major processes of metal cation retention in peat (cation exchange, complexation with peat organics, precipitation as oxides, and precipitation as sulfides), Fe oxidation and Fe binding on peat organics were predominant, with Fe oxides and organically bound Fe making up, respectively, 62 and 22% of the total Fe in the peat at the end of the experiment. Whereas Fe complexation was a finite process, reaching saturation at 12 mg Fe g−1 dry peat, Fe‐oxide concentration in peat increased steadily throughout the experiment. At pH 3.5, Fe‐oxide precipitation was depressed by the addition of an antiseptic (formaldehyde) to AMD, suggesting that the process was microbially mediated. Iron oxide precipitation was higher at pH 5.5 than 3.5 and less depressed at pH 5.5 than 3.5 by the presence of formaldehyde in AMD. The efficiency of peat to remove Fe from AMD was diminished at low temperature (<15°C) and high Fe concentration in AMD (>100 mg L−1). Manganese retention in peat was small compared with that of Fe, and Mn was retained in peat almost exclusively as exchangeable Mn2+. Retention of Fe2+ in peat was not affected by the presence of Mn2+ in AMD. Iron oxides that had accumulated in peat subjected to AMD were not readily resolubilized by any of three processes investigated: photoreduction, microbial Fe(III) reduction under reducing conditions, and exposure to simulated acid precipitation. These findings suggest that constructed wetlands may be an appropriate technology to remove Fe from AMD with low soluble Fe concentration, but are inadequate for treating drainage waters rich in soluble Mn.
Field Corn Response to Acid Rain‐Drought Stress Interaction
Authors: Banwart W. L. , Ziegler E. L. , Porter P. M. 
Published: July 2010

AbstractTwo studies were conducted in 1988 to examine the effects of simulated acid rain in combination with various levels of drought stress on the grain yield of field grown corn (Zea mays L., ‘B73 × Mo17’ and ‘FS854’). In both studies corn was treated with twice weekly applications of simulated rainfall of pH 5.6 or 3.0 at amounts that totaled 100% (30 cm), 50% (15 cm), and 25% (7.5 cm) of the seasonal average for Champaign‐Urbana, IL. In addition to those treatments, in one of the studies the plants were subjected to daily wetting with the appropriate simulated rain from tassel emergence through pollination and fertilization. In both studies, reduced moisture levels resulted in significant reduction in grain yield but simulated rain of pH 3.0 had no effect on yield at any of the moisture levels studied. For both cultivars in both studies, reducing rainfall application from seasonal average to one‐half of the normal decreased yields by approximately 30%. When only one‐fourth of the seasonal rainfall amount was applied, yields were decreased between 40 and 55% compared to the yield for plants receiving the seasonal average rainfall. Results from these studies suggest that application of simulated acid rain of pH 3.0 has little or no negative effect on grain yield of the corn cultivars evaluated, even when relatively severe moisture stress was present, and when plants were subjected to daily wetting from tassel emergence through fertilization.
Beryllium in Selected Southeastern Soils
Authors: Anderson Michael A. , Bertsch Paul M. , Miller William P. 
Published: July 2010

AbstractData regarding the distribution and lability of beryllium (Be) in soils is limited. An interest in the dynamics of Be in soil and aquatic systems prompted this evaluation of the distribution of Be within selected soils of the Piedmont and Coastal Plain physiographic regions of the southeastern USA. Water‐soluble soil Be was below detection limits (<0.2 µg L−1) for all series and depths. Exchangeable Be ranged from <0.1 to 2.2 µmolckg−1, was consistently higher in the Piedmont relative to the Coastal Plain soils, and comprised only 0.0003 to 0.0083% of CEC. Total Be ranged from 0.3 to 30.5 mg kg−1 and, as with exchangeable Be, was consistently higher in the Piedmont soils. No significant correlation between exchangeable and total Be was found (r = 0.28). Exchangeable Be was weakly negatively correlated with depth, however (r = −0.36, significant at 0.10), while total Be tended to increase with depth (r = 0.44, significant at 0.05). Exchangeable Be was also weakly associated with CEC (r = 0.45, significant at 0.05) and exchangeable Ca and Mg (r = 0.39 and 0.38, respectively, both significant at 0.10). Though Al has been previously suggested as a model for Be in soils, no significant association between exchangeable Be and Al was found (r = 0.21). Given the weak association with exchangeable Ca and Mg and the lack of correlation with Al, neither Al nor Ca or Mg appears to serve as an adequate model for Be in southeastern soils.
Cadmium Speciation in Soil Solutions
Authors: Hirsch D. , Banin A. 
Published: July 2010

AbstractTotal Cd concentration was measured in the saturation extract of three unpolluted arid‐zone forest soils to which Cd was added as Cd(NO3)2 solution (0.1 mg Cd kg−1 soil). The ratio of free to total Cd (Cd2+/Cdt) in the extracted soil solution was measured using a Cd selective electrode by an addition method. A chemical equilibrium model including the major complexation reactions of Cd with anionic llgands was used to estimate Cd speciation in solution and was validated by the agreement between the calculated and measured Cd2+/Cdt ratios. Free Cd2+ and CdHCO+3 were each estimated to constitute 35% to 45%, respectively, of total soluble Cd in the calcareous soil solutions studied, which had pH values between 7.5 and 8.5. Agreement between measured and calculated Cd2+/Cdt ratios improved slightly after destruction of organic matter by UV irradiation of the extracted solutions. Organo‐Cd complexes were shown to be present in relatively minor amounts in these soils.
Kinetics of Mercuric Chloride Retention by Soils
Authors: Amacher M. C. , Selim H. M. , Iskandar I. K. 
Published: July 2010

AbstractA nonlinear multireaction model was used to describe kinetic data for HgCl2 retention by five soils. A three‐parameter version of the model consisting of a reversible nonlinear (nth order, n < 1) reaction and an irreversible first‐order reaction was capable of describing HgCl2 retention data for Cecil (clayey, kaolinitic, thermic Typic Kanhapludult) and Windsor (mixed, mesic Typic Udipsamment) soils at all initial solution Hg concentrations, and data for Norwood, [fine‐silty, mixed (calcareous), thermic, Typic Udifluvent], Olivier (fine‐silty, mixed, thermic Aquic Fragiudalt), and Sharkey (very‐fine, montmorillonitic, nonacid, thermic Vertic Haplaquept) soils at initial solution Hg concentrations below 5 mg/L. A five‐parameter version of the model, with an added reversible nonlinear reaction, provided a more accurate description of the retention data for the Norwood, Olivier, and Sharkey soils at initial solution Hg concentrations above 5 mg/L. The second reaction needed to describe the data at higher Hg concentrations suggests the presence of a second type of sorption sites, or a precipitation or coprecipitation reaction not encountered at lower Hg concentrations. Release of Hg from the soils was induced by serial dilution of the soil solution, but not all the soil Hg was reversibly retained. This was also indicated by the model. Release of soil Hg depended on the concentration of retained Hg with significant Hg release occurring only at high concentrations of retained Hg. A multireaction model is needed to describe Hg retention in soils because of the many solid phases that can remove Hg from solution.
Nutrient Export in Stormflow following Forest Harvesting and Site‐Preparation in East Texas
Authors: Blackburn W. H. , Wood J. C. 
Published: July 2010

AbstractIn December 1979 nine small (2.57 to 2.79 ha) watersheds in East Texas were instrumented to determine the effects on stormflow water quality of: (1) clearcutting, shearing, windrowing and burning; (2) clearcutting, roller chopping, and burning; and (3) undisturbed control. Nutrient losses and concentrations, pH, electrical conductivity, and turbidity were not significantly different for all pre‐treated watersheds. The first year following harvesting and site preparation, most nutrient losses and concentrations were greater from the sheared and chopped watersheds than from the undisturbed watersheds. Most nutrient losses and concentrations during the second and third post‐treatment years were not significantly different from the chopped and undisturbed watersheds, but continued to be significantly greater from the sheared watersheds than from chopped or undisturbed watersheds. During the fifth post‐treatment year all nutrient levels except for K+ losses were not significantly different for all treatments. Although nutrient losses from all treatments were small, shearing and windrowing had the greatest impact on nutrient export. Roller chopping as applied in this study had a minimal impact on stormflow nutrient losses and should not degrade water quality.
Influence of Water Chemistry on Suspended Solids in Coal‐Mine Sedimentation Ponds
Authors: Evangelou V. P. 
Published: July 2010

AbstractIn Kentucky, water quality in coal‐mine sedimentation ponds is lowered by high concentrations of suspended solids. Spoil samples from surface mine sites in eastern and western Kentucky were equilibrated with distilled water to evaluate their effects on suspended solids. The results demonstrate that small changes in salt concentration have large effects on suspended solid concentration. Furthermore, it was determined that for the ranges of water chemistry encountered in such environments, there is a linear relationship between the repulsive index [RI = (0.014 EC)−1/2] and suspended solids. Increasing the electrical conductivity (EC) reduces RI and increases the rate of settling.
Internal and External Proton Load to Forest Soils in Northern Germany
Authors: Bredemeier M. , Matzner E. , Ulrich B. 
Published: July 2010

AbstractBoth external and internal proton sources contribute to total H+ load of the soil in terrestrial ecosystems. The most important internal net proton production (INP) processes are (a) accumulation of a surplus of inorganic cations over anions in organic matter, (b) net production and protolysis of organic acids, (c) dissociation of carbonic acid from root and decomposer respiration, (d) net nitrification of organic N, (e) uptake of a surplus of deposited NH+4 over deposited NO−3 or nitrification of deposited NH+4, (f) buffering of deposited H+ in the canopy and recharging of foliar buffer systems with subsequent H+‐release to the soil. Processes (a) through (d) are proton production processes due to ecosystem state and site conditions; (e) and (f) are due to atmospheric deposition and must be regarded as part of acid deposition. The sum of the rates of all processes plus free acidity (H+) flux in throughfall constitute total proton load (TPL) to a soil. Rates of INP and TPL were evaluated for six experimental forests in northwestern West Germany, which had been monitored in long‐term studies. Internal sources are relevant contributors to total proton load. At five of the six sites, however, H+ load due to atmospheric deposition exceeds 70% of TPL. Total acidity budgets show that soils in the aluminum‐buffer‐range become acid exchangers (3H+ → Al3+), i.e., they almost quantitatively transfer the incoming amount of acid (TPL) to deeper layers of the seepage conductor and eventually the hydrosphere. A comparison of the evaluated TPL rates with maximum rates of buffering by silicate weathering reported in the literature indicates that all carbonate‐free soils will further acidify and reach the Al buffer range.
Evaluating Time‐Dependent Tree Ring and Climate Relationships
Authors: Van Deusen P. C. 
Published: July 2010

AbstractTechniques for estimating dynamic tree ring and climate relationships with the Kalman filter have been recently introduced to the field of dendroecology. These methods have been used to evaluate effects of long‐term climate change or pollution impacts on tree growth, thereby enhancing the value of tree rings as a historical data source. The verification of time‐varying trends, however, should be based on replication of results, historical knowledge of the forest, and statistical testing to the extent possible. This article introduces several useful statistical tests for model verification and parameter time‐dependency based on prediction errors and maximum likelihood information criteria.
Copper Fertilization to Prevent Molybdenosis on Retorted Oil Shale Disposal Piles
Authors: Stark John M. , Redente Edward F. 
Published: July 2010

AbstractPlants growing on retorted oil shale disposal piles often have Mo concentrations high enough (>8 mg kg−1) and Cu/Mo ratios low enough (<2.0) to cause molybdenosis in grazing ruminants. High Mo concentrations are present in some plant species in spite of 90 cm of topsoil cover. Copper sulfate was broadcast at rates of 0, 8, 16, and 32 kg Cu ha−1 on plots with 30 and 90 cm of topsoil over Paraho retorted oil shale to determine if Cu fertilization can increase Cu/Mo ratios in plants so that molybdenosis is no longer a hazard. Of the plant species studied winterfat [Eurotia lanata (Pursh) Moquin], northern sweetvetch (Hedysarum boreale Nutt.), alfalfa (Medicago sativa L.), native grasses [Agropyron smithii Rydb., A. inerme (Scribn. and Smith) Rydb., A. dasystachium, (Hook.) Scribn. and Poa ampla Merr.], and introduced grasses [A. desertorum (Fisch.) Schult., A. intermedlum (Host Beauv.), and Bromus biebersteinii Roem. & Schult.], all except alfalfa showed increased tissue Cu concentrations during the first growing season. Because of high Mo concentrations, however, only winterfat under high fertilization rates developed Cu/Mo ratios sufficient to prevent molybdenosis (i.e., >2.0). By the end of the second growing season, increases in Cu concentrations due to fertilization had declined approximately 30%. These results indicate that although Cu fertilization can be used for short‐term improvements in Cu/Mo ratios, it should not be relied upon as the sole technique for preventing molybdenosis on retorted shale disposal piles. Instead, maximum feasible topsoil thicknesses should be used and plant species known to concentrate Mo should be eliminated from seeding mixtures.