bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accumulation, Release, and Solubility of Arsenic, Molybdenum, and Vanadium in Wetland Sediments
Authors: Fox Patricia M. , Doner Harvey E. 
Published: June 2010

ABSTRACTThis study was undertaken to determine the fate of As, Mo, and V (trace elements, TEs) in the sediments of a constructed wetland in use for the remediation of potentially toxic trace element–contaminated agricultural drainwater. After three years of wetland operation, sediment cores were collected to determine changes in TE concentrations as a function of depth and the effects of varying water column depth. All TE concentrations were highest in the top 2 to 4 cm and decreased with depth. Molybdenum accumulated in the wetland sediments, up to levels of 32.5 ± 4.6, 30.2 ± 8.9, and 59.3 ± 26.1 mg kg−1 in the top 1 cm of sediment at water depths of 15, 30, and 60 cm, respectively. In the top 2 cm of sediment, As accumulated (28.2 ± 3.0 mg kg−1) only at the 60‐cm water depth. Below 2 cm, as much as 10 mg kg−1 of As was lost from the sediment at all water depths. In most cases, V concentrations decreased in the sediment. In this wetland system, the lowest redox potentials were found near the sediment surface and increased with depth. Thus, in general As, Mo, and V concentrations in the sediment were highest under more reducing conditions and lowest under more oxidizing conditions. Most of the accumulated Mo (73%) became water soluble on drying of samples. This has important implications for systems undergoing changes in redox status; for instance, if these wetland sediments are dried, potentially large amounts of Mo may be solubilized.
Impact of Genetically Modified Crops on Soil‐ and Plant‐Associated Microbial Communities
Authors: Dunfield Kari E. , Germida James J. 
Published: June 2010

ABSTRACTTransgenic or genetically modified plants possess novel genes that impart beneficial characteristics such as herbicide resistance. One of the least understood areas in the environmental risk assessment of genetically modified crops is their impact on soil‐ and plant‐associated microbial communities. The potential for interaction between transgenic plants and plant residues and the soil microbial community is not well understood. The recognition that these interactions could change microbial biodiversity and affect ecosystem functioning has initiated a limited number of studies in the area. At this time, studies have shown the possibility that transgenes can be transferred to native soil microorganisms through horizontal gene transfer, although there is not evidence of this occurring in the soil. Furthermore, novel proteins have been shown to be released from transgenic plants into the soil ecosystem, and their presence can influence the biodiversity of the microbial community by selectively stimulating the growth of organisms that can use them. Microbial diversity can be altered when associated with transgenic plants; however, these effects are both variable and transient. Soil‐ and plant‐associated microbial communities are influenced not only by plant species and transgene insertion but also by environmental factors such as field site and sampling date. Minor alterations in the diversity of the microbial community could affect soil health and ecosystem functioning, and therefore, the impact that plant variety may have on the dynamics of the rhizosphere microbial populations and in turn plant growth and health and ecosystem sustainability, requires further study.
Assessment of Crown Condition in Eucalypt Vegetation by Remotely Sensed Optical Indices
Authors: Coops Nicholas C. , Stone Christine , Culvenor Darius S. , Chisholm Laurie 
Published: June 2010

ABSTRACTLeaf and crown damage and discoloration characteristics are important variables when defining the health of eucalypt tree species and have been used as key indicators of environmental quality. These indicators can vary significantly over a few hectares, especially in mixed‐species forests, making field‐based environmental surveillance of crown condition an extremely expensive and logistically impractical task. Reflectance in narrow spectral wavelengths obtained from a field‐based spectroradiometer and a Compact Airborne Spectrographic Imager 2 (CASI‐2) were collected over eucalypt vegetation of varying condition in southeastern Australia and compared with leaf‐ and crown‐based attributes including percent red foliage discoloration, percent leaf damage, and crown density and crown foliage condition. Of the leaf attributes sampled, percent leaf damage was well correlated with a red‐green spectral index (r = 0.68, p < 0.01), and percent red discoloration was well correlated with the slope of the red‐edge for selected species (r = 0.89, p < 0.001). Within‐tree crown density was well correlated with the slope of the red‐edge (r = 0.77, p < 0.001) and a previously published index of plant stress with crown foliage condition (r = 0.88, p < 0.01) for selected species. Despite evidence of strong interspecific variability, a set of narrow spectral wavelengths in the visible and near‐infrared regions of the spectrum have been identified that will be useful in the development of forest ecosystem environmental quality indicators.
Reducing Phosphorus Runoff from Swine Manure with Dietary Phytase and Aluminum Chloride
Authors: Smith D. R. , Moore P. A. , Maxwell C. V. , Haggard B. E. , Daniel T. C. 
Published: June 2010

ABSTRACTPhosphorus (P) runoff from fields fertilized with swine (Sus scrofa) manure has been implicated in eutrophication. Dietary modification and manure amendments have been identified as best management practices to reduce P runoff from manure. This study was conducted to compare the effects of dietary modification and aluminum chloride (AlCl3) manure amendments on reducing P in swine manure and runoff. Twenty‐four pens of nursery swine were fed either a normal diet or a phytase‐amended diet. Each pen was connected to a separate manure pit, which was treated with AlCl3 to give final concentrations in the liquid manure of 0 (control), 0.25, 0.50, or 0.75% (v/v). Manure was collected and applied to plots cropped with tall fescue (Festuca arundinacea Schreb.), and simulated rainfall was applied at 50 mm h−1, sufficient to generate a minimum of 30 min of continuous runoff. Samples of manure and runoff were analyzed for P and Al concentrations. Phytase reduced manure soluble reactive phosphorus (SRP) by 17%, while AlCl3 reduced manure SRP by as much as 73% compared with normal manure. Phosphorus runoff was reduced from 5.7 to 2.6 mg P L−1 (a 53% reduction) using AlCl3 The mean SRP concentration in runoff from phytase diets without AlCl3 was 7.1 mg P L−1 during the first rainfall simulation. When phytase and AlCl3 were used together, both manure SRP and P runoff were reduced more than if either treatment were used without the benefit of the other. Use of AlCl3 did not increase soluble Al in manure or Al lost in runoff. Results from this study indicate that producers should use dietary manipulation with phytase and AlCl3 manure amendments to reduce potential P losses from fields fertilized with swine manure.
Hybrid Poplar and Forest Soil Response to Municipal and Industrial By‐Products: A Greenhouse Study
Authors: Cavaleri Molly A. , Gilmore Daniel W. , Mozaffari Morteza , Rosen Carl J. , Halbach Thomas R. 
Published: June 2010

ABSTRACTLittle research has been conducted in the Lake States (Minnesota, Wisconsin, and Michigan) to evaluate the effects of municipal and industrial by‐product applications on the early growth of short rotation woody crops such as hybrid poplar. Anticipated shortages of harvestable‐age aspen in the next decade can be alleviated and rural development can be enhanced through the application of by‐products to forest soils. This study was conducted to evaluate the effects of inorganic fertilizer, boiler ash, biosolids, and the co‐application of ash and biosolids application on tree growth and soil properties by measuring hybrid poplar clone NM‐6 (Populus nigra L. × P. maximowiczii A. Henry) yield, nutrient uptake, and select post‐harvest soil properties after 15 wk of greenhouse growth. Treatments included a control of no amendment; agricultural lime; inorganic N, P, and K; three types of boiler ash; biosolids application rates equivalent to 70, 140, 210, and 280 kg available N ha−1; and boiler ash co‐applied with biosolids. All of the by‐products treatments showed biomass production that was equal to or greater than inorganic fertilizer and lime treatments. A trend of increased biomass with increasing rates of biosolids was observed. Soil P concentration increased with increasing rates of biosolids application. None of the by‐products treatments resulted in plant tissue metal concentrations greater than metal concentrations of plant tissue amended with inorganic amendments. Biosolids, boiler ash, and the co‐application of biosolids and boiler ash together on forest soils were as beneficial to plant growth as inorganic fertilizers.
Laboratory Characterization of Phosphorus in Fresh and Oven‐Dried Organic Amendments
Authors: Ajiboye B. , Akinremi O. O. , Racz G. J. 
Published: June 2010

ABSTRACTThis study was performed to determine the forms of P and to examine the influence of oven‐drying on P forms in different organic amendments. Samples of biosolids, beef and dairy cattle manures, and hog manures from sow and nursery barns were used in this study. Both fresh and oven‐dried amendments were analyzed for inorganic (Pi), organic (Po), and total phosphorus using a modified Hedley fractionation technique. Water extracted about 10% of total biosolids P and 30 to 40% of total hog and cattle manure P. The amount of P extracted by NaHCO3 ranged from 21 to 32% of total P in all organic amendments except in the dairy cattle manure with 45% of total P. The labile P fraction (sum of H2O‐ and NaHCO3–extractable P) was 24% of biosolids P, 60% of hog manure P, and 70% of dairy cattle manure P. The residual P was about 10% in biosolids and cattle manures and 5 to 8% in hog manures. Oven‐drying caused a transformation in forms of P in the organic amendments. In hog manures, H2O‐extractable Po was transformed to Pi, while in the dairy manure NaHCO3–extractable P was converted to H2O‐extractable Pi with oven‐drying. Therefore, caution should be exercised in using oven‐drying for studies that evaluate forms of P in organic amendments. Overall, these results indicate that biosolids P may be less susceptible to loss by water when added to agricultural land.
An Environmental Threshold for Degree of Phosphorus Saturation in Sandy Soils
Authors: Nair V. D. , Portier K. M. , Graetz D. A. , Walker M. L. 
Published: June 2010

ABSTRACTThere is critical need for a practical indicator to assess the potential for phosphorus (P) movement from a given site to surface waters, either via surface runoff or subsurface drainage. The degree of phosphorus saturation (DPS), which relates a measure of P already adsorbed by a soil to its P adsorption capacity, could be a good indicator of that soil's P release capability. Our primary objective was to find a suitable analytical protocol for determining DPS and to examine the possibility of defining a threshold DPS value for Florida's sandy soils. Four farmer‐owned dairy sprayfields were selected within the Suwannee River basin and soil profiles were randomly obtained from each site, as well as from adjacent unimpacted sites. The soil samples were divided either by horizon or depth, and DPS was determined for each soil sample using ammonium‐oxalate (DPSOx), Mehlich‐1 (DPSM1), and Mehlich‐3 (DPSM3) extracts. All methods of DPS calculations were linearly related to one another (r2 > 0.94). Relationships between water‐soluble P and DPS indicate that the respective change points are: DPSOx = 20%, DPSM1 = 20%, and DPSM3 = 16%. These relationships include samples from Ap, E, and Bt horizons, and various combinations thereof, suggesting that DPS values can be used as predictors of P loss from a soil irrespective of the depth of the soil within a profile. Taking into consideration the change points, confidence intervals, agronomic soil test values, and DPS values from other studies, we suggest replacing Mehlich‐1 P values in the Florida P Index with the three DPS categories (DPSM1 = <30, 30–60, and >60%) to assign different P loss ratings in the P Index.
Variation in and Constraints upon the Decomposition of Woolscour Sludge
Authors: Kroening S. J. , Greenfield L. G. , Williamson W. M. 
Published: June 2010

ABSTRACTThe woolscouring (wool washing) industry has traditionally been viewed as highly polluting and, consequently, effluent treatment systems have been sought. The first stage in the current treatment system for woolscour wastewater, a chemical flocculation process (Sirolan CF), creates a sludge composed of soil and wool grease. We investigated the chemical and biological characteristics of this sludge. The sludge was found to be highly variable on a day to day basis in terms of its chemical composition and biodegradability; 0.8 to 27.8% of sludge total nitrogen was mineralized over 30 d at 37°C. The grease component of sludge (14–40% on a dry weight basis) may retard the decomposition of the sludge but the polyacrylamide flocculant used in its production and its pesticide content had no effect on the rate of decomposition. Our results suggest that variability in substrate quality may translate into variability in treatment performance and have important implications for the biological treatment of industrial wastes, including composting.
An Assessment of Nitrogen‐Based Manure Application Rates on 39 U.S. Swine Operations
Authors: Lory John A. , Massey Raymond E. , Zulovich Joseph M. , Hoehne John A. , Schmidt Amy M. , Carlson Marcia S. , Fulhage Charles D. 
Published: June 2010

ABSTRACTWater quality concerns and revised regulations are changing how confined animal feeding operations manage manure. Devising acceptable and feasible changes in manure practices requires a full understanding of the forces shaping current manure management decisions. Previous theoretical models have shown that a wide range of factors influence the lowest cost solution for manure management. We used a mechanistic model to characterize the manure management practices on 39 swine operations (20 unagitated lagoon and 19 slurry operations) in five states (Iowa, Missouri, North Carolina, Oklahoma, and Pennsylvania). Information was collected from each operation about animal numbers, feed and water use, manure handling and storage characteristics, field locations, crop rotation, fertilizer need, and equipment inventory and usage. Collected data were used as input and to validate results from a mechanistic model that determined acres required for manure application, manure application rate, time required for manure application, value of manure, and costs of manure management. The 39 farms had a mean of 984 animal units (AU) per operation, 18.2 AU ha−1 (7.4 AU acre−1), and manure application costs of $10.49 AU−1 yr−1 Significant factors affecting manure management included operation size, manure handling system, state, and ownership structure. Larger operations had lower manure management costs (r2 = 0.32). Manure value potentially exceeded manure application costs on 58% of slurry and 15% of lagoon operations. But 38% of slurry operations needed to apply manure off the farm whereas all lagoon operations had sufficient land for N‐based manure management. Manure management was a higher percentage of gross income on contract operations compared with independents (P < 0.01). This research emphasized the importance of site‐specific factors affecting manure management decisions and the economics of U.S. swine operations.
Application of a Slow‐Release Fertilizer for Oil Bioremediation in Beach Sediment
Authors: Xu R. , Lau N. L. A. , Ng K. L. , Obbard J. P. 
Published: June 2010

ABSTRACTA 105‐d field experiment was conducted to determine the potential of the slow‐release fertilizer, Osmocote (Scotts, Marysville, OH), to stimulate the indigenous microbial biodegradation of petroleum hydrocarbons in an oil‐spiked beach sediment on an intertidal foreshore in Singapore. Triplicate microcosms containing 80 kg of weathered sediment, spiked with 5% (w/w) Arabian light crude oil and 1.2% (w/w) Osmocote pellets, were established, together with control microcosms minus Osmocote. Relative to the control, the presence of the Osmocote sustained a significantly higher level of nutrients (NH4+–N, NO3−–N, and PO43−–P) in the sediment pore water over the duration of the experiment. The metabolic activity of the indigenous microbial biomass, as measured using an intracellular dehydrogenase enzyme assay, was also significantly enhanced over the duration of the experiment in amended sediments. The loss of total recoverable petroleum hydrocarbons (TRPH) and biodegradation of total n‐alkanes (C10–C33), branched alkanes (pristane and phytane), as well as total target polycyclic aromatic hydrocarbons (PAHs) (two‐ to six‐ring), in both the control and Osmocote‐amended sediments, followed a first‐order biodegradation model. The first‐order loss rate of total recoverable petroleum hydrocarbons was 2.57 times greater than that of the control. The hopane‐normalized rate constants for total n‐alkane, branched alkane, and total target PAH biodegradation in the Osmocote‐treated sediments were 3.95‐, 5.50‐, and 2.45‐fold higher than the control, respectively. Overall, the presence of Osmocote was able to significantly enhance and accelerate the biodegradation of aliphatics and PAHs in oil‐contaminated sediments under natural field conditions in an intertidal foreshore environment.
Tillage and Manure Application Effects on Mineral Nitrogen Leaching from Seasonally Frozen Soils
Authors: Gupta Satish , Munyankusi Emmanuel , Moncrief John , Zvomuya Francis , Hanewall Matt 
Published: June 2010

ABSTRACTLand application of manure is a common practice in the Upper Midwest of the United States. Recently, there have been concerns regarding the effect of this practice on water quality, especially when manure is applied during winter over frozen soils. A study undertaken on a Rozetta silt loam (fine‐silty, mixed, superactive, mesic Typic Hapludalfs) at Lancaster, WI, evaluated the effects of tillage and timing of manure application on surface and subsurface water quality. The daily scrape and haul liquid dairy manure was applied either in the fall (before snow) or in winter (over snow with frozen soil underneath) to be compared with no manure under two tillage systems (no‐till and chisel‐plowing). In this paper, we report results on the effects of the above treatments on mineral N leaching. Percolation and mineral N leaching during the nongrowing season were, respectively, 72 and 78% of the annual losses, mainly because of the absence of plant water and N uptake. Percolation was generally higher from no‐till compared with chisel‐plow but there was no significant effect of tillage on mineral N concentration of the leachate or mineral N losses via leaching. Mineral N leaching was statistically higher from the manure‐applied vs. no‐manure treatment, but there was no difference between winter‐applied manure and no‐manure treatments. There were significant tillage by manure interactions with fall manure application followed by chisel‐plowing resulting in highest N leaching losses. Averaged over the two years, N leaching rates were 52, 38, and 28 kg N ha−1 yr−1 from fall‐applied, winter‐applied, and no‐manure treatments, respectively. These results show that there is substantial N leaching from these soils even when no fertilizer or manure is applied. Furthermore, fall‐applied manure followed by fall tillage significantly increases N leaching due to enhanced mineralization of both soil and manure organic N.
In Situ Speciation Studies of Copper–Humic Substances in a Contaminated Soil during Electrokinetic Remediation
Authors: Liu S.‐H. , Wang H. Paul 
Published: June 2010

ABSTRACTSpeciation of copper–humic substances (HS) in the electrokinetic remediation (EKR) of a contaminated soil was studied by in situ extended X‐ray absorption fine structure (EXAFS) and X‐ray absorption near edge structure (XANES) spectroscopies. The least‐square fits of the XANES spectra suggested that the main Cu species in the contaminated soil were Cu–HS (50%), CuCO3(28%), Cu2O (11%), and CuO (11%). The Cu–HS in the contaminated soil possessed equatorial and axial Cu–O bond distances of 1.94 and 2.17 Å with coordination numbers (CNs) of 3.6 and 1.4, respectively. In the EKR process, the axial Cu–O bond distance in the Cu–HS complexes was increased by 0.15 Å, which might be due to a ligand exchange of the Cu–HS with H2O molecules in the electrolyte. After 180 min of EKR, about 50% of the Cu–HS complexes (or 24% of total Cu) in the soil were dissolved and formed [Cu(H2O)6]2+in the electrolyte, 71% (or 17% of total Cu in the soil) of which were migrated to the cathode under the electric field (5 V/cm). This work exemplifies the use of in situ EXAFS and XANES spectroscopies for speciation studies of Cu chelated with HS in the contaminated soil during EKR.
Spectroscopic Speciation and Quantification of Lead in Phosphate‐Amended Soils
Authors: Scheckel Kirk G. , Ryan James A. 
Published: June 2010

ABSTRACTThe immobilization of Pb in contaminated soils as pyromorphite [Pb5(PO4)3Cl, OH, F] through the addition of various phosphate amendments has gained much attention in the remediation community. However, it is difficult to fully determine the speciation and amount of soil Pb converted to pyromorphite by previously employed methods, such as selective sequential extraction procedures and scanning electron microscopy coupled with energy dispersive X‐ray spectroscopy, which often lead to erroneous results in these non‐equilibrated and heterogeneous systems. Statistical analysis by linear combination fitting (LCF) applied to X‐ray absorption fine structure (XAFS) spectroscopic data of Pb‐contaminated soil samples relative to known Pb reference material provides direct, in situ evidence of dominate Pb species in the amended soils without chemical or physical disruption to the Pb species as well as a weighted quantification output. The LCF–XAFS approach illustrated that pyromorphite concentration ranged from 0% (control soil) to 45% (1% phosphoric acid amendment, residence time of 32 mo) relative to the total Pb concentration. The Pb speciation in the nonamended control soil included Pb–sulfur species (galena + angelsite = 53%), adsorbed Pb (inner‐sphere + outer‐sphere + organic‐bound = 45%), and Pb–carbonate phases (cerussite + hydrocerussite = 2%). The addition of P promoted pyromorphite formation and the rate of formation increased with increasing P concentration (up to 45%). The supplemental addition of an iron amendment as an iron‐rich byproduct with triple superphosphate (TSP) enhanced pyromorphite formation relative to independent TSP amendment of like concentrations (41 versus 29%). However, the amendment of biosolids and biosolids plus TSP observed little pyromorphite formation (1–16% of total Pb), but a significant increase of sorbed Pb was determined by LCF–XAFS.