bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cadmium in Australian Potato Tubers and Soils
Authors: McLaughlin M. J. , Maier N. A. , Rayment G. E. , Sparrow L. A. , Berg G. , McKay A. , Milham P. , Merry R. H. , Smart M. K. 
Published: July 2010

AbstractCadmium (Cd) has been identified as a potential contaminant in foods posing health risks to humans and, in Australia, potatoes (Solanum tuberosum L.) have been identified as contributing a large proportion of the average dietary Cd intake. To assess the concentrations of Cd in Australian potatoes and soil factors likely to lead to high Cd concentrations, commercial crops and soils were sampled at 352 sites throughout potato production areas in Australia. Across all states, fresh weight (FW) tuber Cd concentrations ranged from 0.004 to 0.232 mg kg−1 with an overall mean value of 0.041 and a median of 0.033 mg kg−1 (FW). Approximately 92 samples out of 359 (25.6%) exceeded the current maximum permitted concentration (MPC) of 0.05 mg kg−1 (FW) and 18 (5.0%) exceeded 0.1 mg kg−1 (FW). Concentrations of Cd (EDTA‐extractable) in topsoils ranged from 0.01 to 0.59 mg kg−1 with mean and median values of 0.14 and 0.10 mg kg−1, respectively. There was no relationship between Cd concentrations in soil and tubers. Stepwise forward multiple regression analysis of the data indicated that Cl and Zn concentrations in the topsoil, soil pH, and potato cultivar accounted for 57% of the variation in tuber Cd concentrations, with Cl being the dominant factor. Comparison of soil‐plant transfer coefficients (TCs) for Cd with limited international data sets suggests that TCs for Australian soils used for potato production are relatively high.
Mineralizable Nitrogen in Broiler Litter: I. Effect of Selected Litter Chemical Characteristics
Authors: Gordillo R. M. , Cabrera M. L. 
Published: July 2010

AbstractBroiler (chicken, Gallus gallus domesticus) litter is a mixture of manure and bedding material that is generated in large amounts by the broiler industry. This litter is typically applied to land as fertilizer, at rates estimated to supply adequate N. Estimation of rates is currently hampered by the lack of rapid methods to determine mineralizable N in BL. This study was conducted to compare the kinetics of N mineralization of 15 BL samples, and to evaluate selected chemical characteristics of the litter as predictors of mineralizable N. Broiler litter samples were mixed with samples of Cowarts soil (150 mg organic N kg−1 soil, −0.02 MPa) and incubated at 25°C for 112 d. Cumulative net N mineralized was fitted to a two‐pool, first‐order model, to determine the size of fast and slow pools of mineralizable N. The fast N pool varied from 116 to 569 g N kg−1 organic N (ON), and could be predicted from uric acid‐N concentration in the litter (R2 = 0.92). The size of the slow N pool did not vary significantly among BL samples; (309 ± 94 g N kg−1 ON). Total mineralizable N (fast + slow N pools) ranged from 465 to 868 g N kg−1 ON, and could be predicted from uric acid‐N and total N concentrations (R2 = 0.91), or from uric acid‐N concentration and C/N of the litter (R2 = 0.95). The simplicity of the chemical indices involved should make this approach attractive to estimate mineralizable N in BL.
Evaluation of Nitrate Leaching Potential in Minnesota Glacial Outwash Soils using the CERES‐Maize Model
Authors: Pang X. P. , Gupta S. C. , Moncrief J. F. , Rosen C. J. , Cheng H. H. 
Published: July 2010

AbstractThis study examined how the CERES‐Maize model could be used to identify N and irrigation management practices that minimize nitrate leaching as well as provide economical corn (Zea mays L.) yield in glacial outwash soils of Minnesota. The model was validated against 2 yr of experimental data on corn grain yield, N uptake, and nitrate leaching for control and three N fertilizer application rates under two irrigation schedules on a sandy loam soil at Staples, MN. Simulated values were close to the measured corn yield, and were within the range of differences for similar comparisons. Simulations using 31 yr of climatic data showed that an irrigation trigger deficit as low as 30% had little impact on corn yield but significant impact on reduced percolation and nitrate leaching. A procedure was developed to characterize the potential of nitrate leaching in outwash soils using the output from the CERES‐Maize model. We used this procedure to characterize nitrate leaching from soils in Wadena County, MN. As expected, the high risk soils had the lowest water holding capacity and the highest drainage coefficient. The factors affecting the risk of nitrate leaching are: irrigation schedule > climatic variability = N application rate. Linking a validated simulation model with a soil survey data base provides a valuable tool in site specific assessment and prescription of best irrigation and N management practices for the glacial outwash soils of the North Central region.
Fecal Coliform Transport through Intact Soil Blocks Amended with Poultry Manure
Authors: McMurry S. W. , Coyne M. S. , Perfect E. 
Published: July 2010

AbstractPoultry production in Kentucky increased almost 200% between 1991 and 1995. Their waste is typically land applied, and fecal pathogen runoff and infiltration may cause nonpoint source groundwater pollution. We looked at the preferential flow of fecal coliforms through undisturbed soil blocks since fecal bacteria typically infiltrate the soil profile to contaminate groundwater. Poultry manure was uniformly distributed on top of sod‐covered or tilled (upper 12.5 cm) soil blocks and the blocks were irrigated. Drainage was collected in 100 uniformly spaced cells beneath each block and analyzed for fecal coliform content and drainage volume. The spatial distribution of drainage and fecal coliforms through the soil blocks was not uniform. Fecal coliforms appeared where most drainage flowed. Drainage water from each soil block consistently exceeded 200 000 fecal coliforms per 100 mL and was as great as 30 million fecal coliforms per 100 mL of leachate collected. Fecal coliforms leached as a pulse, but the breakthrough of fecal coliforms through tilled blocks was delayed with respect to the breakthrough of fecal coliforms through sod‐covered blocks. Rainfall on a well‐structured soil will cause the preferential movement of fecal bacteria, even with unsaturated flow conditions, and could contribute to fecal coliform concentrations in shallow groundwater that exceed standards for domestic discharge and primary contact water in Kentucky (200 fecal coliforms/100 mL).
Decreasing Metal Runoff from Poultry Litter with Aluminum Sulfate
Authors: Moore P. A. , Daniel T. C. , Gilmour J. T. , Shreve B. R. , Edwards D. R. , Wood B. H. 
Published: July 2010

AbstractAluminum sulfate [Al2(SO4)3·14H2O] applications to poultry litter can greatly reduce P concentrations in runoff from fields fertilized with poultry litter, as well as decrease NH3 volatilization. The objective of this study was to evaluate metal runoff from plots fertilized with varying rates of alum‐treated and untreated (normal) poultry litter. Alum‐treated (10% alum by weight) and untreated litter was broadcast applied to small plots in tall fescue (Festuca arundinacea Schreb.). Litter application rates were 0, 2.24, 4.49, 6.73, and 8.98 Mg ha−1 (0, 1, 2, 3, and 4 tons acre−1). Rainfall simulators were used to produce two runoff events, immediately after litter application and 7 d later. Both concentrations and loads of water‐soluble metals increased linearly with litter application rates, regardless of litter type. Alum treatment reduced concentrations of As, Cu, Fe, and Zn, relative to untreated litter, whereas it increased Ca and Mg. Copper concentrations in runoff water from untreated litter were extremely high (up to 1 mg Cu L−1), indicating a potential water quality problem. Soluble Al, K, and Na concentrations were not significantly affected by the type of litter. Reductions in trace metal runoff due to alum appeared to be related to the concentration of soluble organic C (SOC), as well as the affinity of SOC for trace metals. Metal runoff from alum‐treated litter is less likely to cause environmental problems than untreated litter, since threats to the aquatic environment by Ca and Mg are far less than those posed by As, Cu, and Zn.
Reducing Soil Phosphorus Solubility with Coal Combustion By‐Products
Authors: Stout William L. , Sharpley Andrew N. , Pionke Harry B. 
Published: July 2010

AbstractIn the northeast USA, most soil samples analyzed for soil test P (STP) in 1990 exceeded P levels needed for plant production. Converting soil P to less soluble forms with applications of materials containing lime or Ca may reduce the release of soil P to runoff. We investigated the effect of several coal combustion by‐products on STP (Bray‐1 and Mehlich‐III), water extractable P, and equilibrium P concentration (EPC0) of high P soils. Three widely available by‐products were used: fluidized bed combustion fly ash (FBC), flue gas desulfurization by‐product (FGD), and pulverized coal flyash (PC). In a by‐product type and rate experiment, a Berks soil with high STP was incubated for 21 d with each by‐product (0, 10, 20, 40, and 80 g kg soil−1). The highest rates of FBC and FGD reduced Mehlich‐III P (45%), Bray‐I P (50%), water extractable P (72%) and EPC0 (37%). The PC had no effect on soil P solubility due to the addition of P with this by‐product. For eight soils ranging in physical and chemical properties, FBC at 10 g kg soil−1 reduced Mehlich‐III P 13%, and water‐extractable P 71%, while FGD reduced Mehlich‐III P 8% and water‐extractable P 48%. These reductions resulted from the conversion of readily desorbable soil P to less soluble Ca‐bound or Al‐ and Fe‐bound pools. Amending high P soils with FBC or FGD by‐products has the potential to reduce P enrichment of runoff by decreasing the solubility of soil P without reducing STP below optimum levels for plant growth.
Land Use and Soil Nitrogen Status in a Tropical Pacific Island Environment
Authors: Motavalli P. P. , McConnell J. 
Published: July 2010

AbstractThe rapid rate of land development in the Micronesian Region of the Pacific Ocean has raised public concern over the effects of land disturbance and land use on potential NO−3 pollution and other longterm impacts on soil properties. Our objective was to compare the soil N status and other soil chemical and physical properties of several land use sites on Guam, including an area under secondary forest vegetation, an area under continuous cultivation, an area recently cleared for agriculture, and an abandoned agricultural area. Continuous agricultural cultivation over a 7‐yr period increased soil bulk density and soil pH and lowered water‐holding capacity, organic C, total N, and N mineralization compared with soil in a forested site. Soil organic N fractions, including microbial biomass N and particulate organic matter N, were reduced by the mixing effects of tillage in the cultivated site. Initial clearing of vegetation increased bulk density and pH but did not decrease soil organic C and N compared with the forest site. Soil at an agricultural site that had been abandoned for an 11‐yr period did not return to levels of organic C, total N, and N mineralization observed in the forest and cleared sites. These results suggest that long‐term tillage has a significant impact on soil properties in this tropical island environment, including reducing active and stable N pools. However, the significance of these changes on NO−3 leaching is unclear because of alterations in soil properties affecting both soil water movement and other N processes.
Aquifer Denitrification as Interpreted from In Situ Microcosm Experiments
Authors: Bates H. K. , Spalding R. F. 
Published: July 2010

AbstractDenitrification of 40 mg L−1 NO3‐N groundwater in the vicinity of Central City, NE was stimulated with ethanol in in situ microcosms that were vibrated into the aquifer sediment and, thus, filled with a relatively undisturbed, saturated sand and gravel matrix. In microcosms receiving the 1.25 C/N ratio, nitrate disappeared within 40 h; however, NO2‐N accumulated and persisted after NO3‐N was depleted. Nitrite has been documented in groundwater redoxclines and is expected to be reported more frequently with increased use of ion chromatography and dense sampling networks. Dissolved oxygen was consumed to <2.0 mg L−1 within 15 h, and stoichiometric production of HCO−3 occurred. Average denitrification rate decreased from 28.5 to 19.3 and to 16 mg N L−1 d−1 for C/N ratios of 1.25, 2.5, and 5.0 mg L−1. Kinetic N‐isotope effects resulted in the δ15N enrichment of residual nitrate as denitrification progressed, thus, causing the initial δ15N value of ∼+6‰ to increase to > +20‰. The data support measuring additional parameters to prevent misinterpretations when using δ15N values in NO−3 source identification investigations. Apparent isotope‐enrichment factors, ε value, were derived from δ15N increases vs. NO−3 and NO3 plus NO−2 reduction. They ranged from −11 to −16‰ for δ15N vs. residual NO−3 plus NO−2 and from −2.5 to −9‰ for δ15N vs. NO−3 alone. Since NO−3 could not be resolved from NO−2 in the δ15N analysis, a δ15N depleted NO2 phase was not identified. Nevertheless, isotopically light enrichment factors are consistent with the presence of NO−2.
Minesoil and Site Properties Associated with Early Height Growth of Eastern White Pine
Authors: Andrews Jeffrey A. , Johnson James E. , Torbert John L. , Burger James A. , Kelting Daniel L. 
Published: July 2010

AbstractA study was established to investigate soil and site variables associated with early growth of eastern white pine (Pinus strobus L.) on reclaimed strip mines in southern West Virginia and Virginia. A total of 78 plantations were studied on 14 different mines, 5 to 9 yr following planting. Two‐year terminal height growth at ages 4 and 5 was selected as the growth variable in a multiple linear regression equation developed to show the relationship between tree growth and soil and site variables. Many soil/site variables were tested, but rooting depth, electrical conductivity, surface soil P and Mn, and slope were the dominant independent variables, accounting for 48% of the variability in growth. Soil depth had a standardized regression coefficient of 0.35, and was the most significant variable. Through proper reclamation, it is possible to establish a site that will not only provide for adequate early height growth to facilitate bond release, but also provide for future long‐term productivity of surface‐mined lands.
Geophysical Electromagnetic Survey Methods Applied to Agricultural Waste Sites
Authors: Eigenberg R. A. , Korthals R. L. , Nienaber J. A. 
Published: July 2010

AbstractThis paper reports the use of electromagnetic (EM) instrumentation for surveying agronomic and waste treatment sites at locations previously profiled by soil coring for evaluation of nutrients in the soil profile. Surveys were made using a geophysical EM instrument capable of measuring conductivity 3 to 6 m below the surface of the ground with horizontal or vertical polarization. Two specific sites were analyzed to evaluate the effects of management practices: (i) An animal waste composting site with one section in use since 1985 and with expanded operation to another section in 1989 and (ii) A waste storage pond (operational in 1973) holding precipitation runoff from a cattle feedlot. Correlation analysis between the EM conductivity measurements and chemical analysis at both sites (concentrations of NH+4, NO−3, CL−, and P) show significant (P < 0.05) correlations for the ions while P did not show a significant correlation. The EM measures were able to distinguish the 6‐yr‐old site from the 10‐yr‐old site (P < 0.05). The results indicate that EM methods provide useful information for shallow subsurface surveys of livestock waste management facilities.
Adsorption of Naphthalene onto Plant Roots
Authors: Schwab A. P. , Al‐Assi A. A. , Banks M. K. 
Published: July 2010

AbstractHigher plants are being used to enhance the remediation of soils contaminated with recalcitrant organic compounds, but the mechanisms of dissipation have not been established. One possible step in the phytoremediation process is adsorption of the organic contaminant onto the surface of the roots and subsequent uptake and/or degradation. To determine the affinity of plant roots for naphthalene, a polycyclic aromatic hydrocarbon, adsorption was quantified for tall fescue (Festuca arundinacea Schreber) and alfalfa (Medicago sativa Equilibrium adsorption for naphthalene was determined for fresh roots of each species at three growth stages. For both fescue and alfalfa, adsorption was described by the Freundlich isotherm. Adsorption increased by as much as a factor of four with later growth stage of the plants. Alfalfa roots had approximately twice the affinity for naphthalene than fescue roots, despite a greater surface area per unit mass of root for fescue. Alfalfa also had a greater lipid content than fescue (10 g lipid/kg dry root vs. 4.5 g/kg), indicating that lipid content is a controlling factor in adsorption of naphthalene onto plant roots.
Comparison of Closed‐Chamber and Bowen‐Ratio Methods for Determining Methane Flux from Peatland Surfaces
Authors: Chan A. S. K. , Prueger J. H. , Parkin T. B. 
Published: July 2010

AbstractMethane (CH4) is an important greenhouse gas, and it has been estimated that 50% of annual CH4 comes from terrestrial systems. Better and more accurate methods are needed to quantify CH4 flux from terrestrial environments. Two general methods commonly applied to measure trace gas fluxes are soil cover (chamber) techniques, and micrometeorology methods. Both of these methods has advantages and disadvantages, yet little information is available concerning the relative performance of the techniques. This study was conducted to compare CH4 flux measurements obtained by using a closed‐chamber soil cover technique and a micrometeorological method (Bowen‐ratio Energy Balance [BREB]). Methane flux rates obtained by both methods were compared using nine time points over 3 d at a peatland site in north central Minnesota. Mean CH4 fluxes obtained by both methods were of the same magnitude (2.43–5.88 mg CH4 m−2 h−1); however, differences were observed in the magnitudes of temporal variability as well as the detection sensitivities (minimum detectable flux). The minimum detectable flux for the closed‐chamber method was 9.32 × 10−2 mg CH4 m−2 h−1, while the minimum detectable flux for the BREB method ranged from 2.16 to 25.5 mg CH4 m−2 h−1. Due to analytical uncertainties associated with gas chromatographic determination of CH4 gradients, the BREB is not recommended.
Method for Estimating Bulk Density of Soft‐Bottom Sediment Cores
Authors: van Dokkum H. P. , van Leerdam M. E. , Anderson D. L. , Aalderink R. H. , Vermulst C. J. W. , Abbink Spaink A. P. 
Published: July 2010

AbstractSoft‐bottom highly porous sediment samples can be frozen to facilitate handling, preservation, and especially separation of sediment layers before laboratory analysis. Due to core expansion upon freezing, bulk density measurements are biased (underestimation of up to 8.9% for pure water), but bulk density in separate sediment layers can only be measured after freezing. Therefore, the objective of this study was to develop a methodology that allows the actual field bulk density to be estimated from measurements on frozen cores in the laboratory. Homogeneous soft‐bottom undisturbed sediment cores (single layer) were sampled with a transparent cylindrical device in the Everglades Agricultural Area. The bulk density of the undisturbed, unfrozen sediment cores (field bulk density) was calculated by measurement of the volume and weight of sediment cores. After freezing, the solids fraction and frozen bulk density on a wet‐basis were determined. From the collected data, the field (i.e., before freezing) bulk density could adequately be predicted from the frozen bulk density and the solids fraction. The method described in this paper allows field bulk density of separate sediment layers to be estimated from parameters easily measured on frozen sediment cores, and is therefore useful when different sediment layers require delineation.
The Role of Phosphorus in the Eutrophication of Receiving Waters: A Review
Authors: Correll David L. 
Published: July 2010

AbstractPhosphorus (P) is an essential element for all life forms. It is a mineral nutrient. Orthophosphate is the only form of P that autotrophs can assimilate. Extracellular enzymes hydrolyze organic forms of P to phosphate. Eutrophication is the overenrichment of receiving waters with mineral nutrients. The results are excessive production of autotrophs, especially algae and cyanobacteria. This high productivity leads to high bacterial populations and high respiration rates, leading to hypoxia or anoxia in poorly mixed bottom waters and at night in surface waters during calm, warm conditions. Low dissolved oxygen causes the loss of aquatic animals and release of many materials normally bound to bottom sediments including various forms of P. This release of P reinforces the eutrophication. Excessive concentrations of P is the most common cause of eutrophication in freshwater lakes, reservoirs, streams, and headwaters of estuarine systems. In the ocean, N becomes the key mineral nutrient controlling primary production. Estuaries and continental shelf waters are a transition zone, where excessive P and N create problems. It is best to measure and regulate total P inputs to whole aquatic ecosystems, but for an easy assay it is best to measure total P concentrations, including paniculate P, in surface waters or N/P atomic ratios in phytoplankton.
Organic Compound Sorption Enthalpy and Sorption Mechanisms in Soil Organic Matter
Authors: Borisover Mikhail D. , Graber Ellen R. 
Published: July 2010

AbstractSmall exothermic or even endothermic heats of sorption for organic compounds in soil organic matter (SOM) have been traditionally considered evidence for a partitioning mechanism into the bulk of SOM. This derives from considerations of solute transfer enthalpy (ΔHtr) from aqueous solution to organic solvent and partial molar enthalpies of solution in organic solvent (ΔHssol) and aqueous (−ΔHwsol) phases, where ΔHtr = ΔHssol − ΔHwsol. The dissolution of many solutes in organic solvents is accompanied by positive solution enthalpies and conforms to the condition ΔHtr > −ΔHwsol. It was suggested by analogy of SOM to organic solvents, that solute sorption enthalpies (ΔHi) in SOM that conform to the analogous condition (i.e., ΔHi > ΔHwsol) are consistent with partitioning into SOM. Systems that do not conform to this condition (i.e., ΔHi < ΔHwsol) were considered to be consistent with adsorption. The purpose of this analysis is to point out the fallacies associated with this reasoning and to demonstrate that sorption enthalpy cannot be used in this way as evidence for a particular sorption mechanism. It is shown that for partitioning of numerous organic solutes into different organic solvents, ΔHssol < 0, such that ΔHtr < −ΔHwsol. If SOM is considered the solvent phase, it is clear that ΔHi < −ΔHwsol cannot be taken to indicate surface adsorption. This is particularly true for systems that provide an opportunity for strong force specific interactions inside of SOM. Similarly, it is shown that systems involving adsorption of nonpolar organic compounds at mineral surfaces often conform to the condition suggested as evidence for partitioning.