bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship of the Nature of Suspended Clay Minerals to Hydrologic Conditions
Authors: Laird David , Harward M. E.
Published: July 2010

The clay mineralogy of sediments in suspended transport and their relationship to soils of a small agricultural watershed in western Oregon were evaluated. The clay fraction (<2 µm) was separated from suspended sediment and watershed surface soil samples by centrifugation in distilled water. Half of the clay fraction of each sample was Mg2+‐saturated and the other half was K+‐saturated. Slides of both the Mg2+‐ and K+‐saturated fractions were prepared and subjected to a sequence of characterization treatments. After each treatment the samples were analyzed using copper k‐alpha radiation on a Norelco x‐ray diffractometer.

It was initially anticipated that the characteristics of sediments would change with progression of the rainfall season as downcutting began to erode material from the upper B horizon. However, no general seasonal trend in the nature of suspended clays was observed. Rather, the character of the entrained clay minerals was dependent on the type of hydrologic event. During high‐energy hydrologic conditions, the clay mineralogy of suspended sediments was similar to that of the upper horizons of the watershed soils. In low‐energy hydrologic conditions, the suspended sediments were enriched with well‐organized kaolinite and smectite and depleted of chloritic intergrades. Selective dispersion combined with preferential settling of “nondispersed” materials are thought to be the mechanisms involved with this phenomenon.
Fluoride‐Induced Mobilization and Leaching of Organic Matter, Iron, and Aluminum
Authors: Polomski Janina , Flühler H. , Blaser P.
Published: July 2010

In order to demonstrate the effects of F‐induced leaching of organic matter, Al, and Fe, different soil samples were percolated under laboratory conditions at constant flow with distilled water and various solutions containing F or Cl, applied as NaF, KF, Na5Al3 F14, KCl, and NaCl, respectively.

The three sets of experiments focus on the following questions: (i) Are the observed leaching losses primarily F‐induced? (ii) How do they relate to the F concentrations of the solutions? and (iii) To what extent are calcareous soils resistant to and acid soils prone to F‐induced leaching?

Total organic carbon (TOC), Fe, and especially Al were leached more effectively when the percolating solution contained F instead of Cl. The cationic composition of the solution was definitely less important than the concentration of dissolved F. For instance, the F‐induced Al leaching loss from an acid clay soil was nine times larger than that of an equimolar NaCl solution. In the concentration range of 0 to 50 µg mL−1 dissolved F the peak concentrations of Al in the outflow samples varied from 0.2 to 26.0 µg Al mL−1. The leaching losses from the acid soil were significantly higher than those from the two calcareous soils. However, TOC leaching with distilled water was highest in the case of the severely F‐contaminated calcareous soil.
Accumulation of Airborne Fluoride in Soils
Authors: Polomski Janina , Flühler H. , Blaser P.
Published: July 2010

Soil contamination by atmospheric fluorides was studied in the vicinity of an aluminum smelter. Soil profiles at various distances from the emission source were sampled and the samples analyzed for total and water‐extractable F. Both measurements, in particular the water‐extractable fraction, reflected the gradient of F exposure. The F concentration of the soil solution exhibited a similar dependence upon distance from the emission source. Over a distance of 8.8 km the total F concentration decreased from 2,700 to 616 µg F g−1, the water‐extractable fraction from 292 to 10 µg F g−1, and the F concentration in the soil solution from 8.2 to 0.3 µg F mL−1.

Within an extensively sampled profile, the total F concentration was more‐or‐less constant, whereas the water‐extractable fraction increased significantly with depth.

A soil column experiment was conducted in the field in order to estimate the rate of F accumulation and translocation. The F fluxes into and out of the main root zone were estimated to be in the order of 7.7 ± 3.5 and 5.4 ± 2.1 g F m−2 year−1, respectively, which is roughly an equivalent of 5% of the F stored in a comparable uncontaminated profile.
Plutonium Contents and Fluxes in a Soybean Crop Ecosystem Near a Nuclear Fuel Chemical Separations Facility
Authors: Adriano D. C. , Pinder J. E. , Mc Leod K. W. , Corey J. C. , Boni A. L.
Published: July 2010

A soybean (Glycine max) crop was grown in fields within 1 km of a nuclear fuel chemical separations plant at the Savannah River Plant, S.C. Aerial releases of 238Pu and 239,240Pu have been occurring at various rates during the past 25 years and have produced characteristic Pu isotopic ratios (ISR) in various environmental matrices. This unique situation, along with pot studies and a farm site receiving only global fallout, provided the opportunity to study various biological and physical processes that determine Pu contamination of ecosystems and their components.

Contamination of the external surfaces of the soybeans contributed more to Pu contamination than did root uptake and translocation. Contamination of beans harvested with a combine was also mostly surficial, indicating that physical processes are more important than biological processes in this “real‐world” situation. Pu‐bearing particles directly deposited from the point source (62‐m stack) and soil‐surface resuspendible materials were the primary contaminants for the vegetation, while resuspension and transfer of Pu‐bearing particles from vegetative surfaces were the dominant ones for the harvested beans. The Pu input from this particular chemical separations facility to the foodstuff (soybean beans) contributed little to radiation dose to humans compared with the natural background radiation.
Bioavailability of Phosphorus Inputs to Lakes
Authors: Sonzogni W. C. , Chapra S. C. , Armstrong D. E. , Logan T. J.
Published: July 2010

Interpretation of the potential bioavailability of phosphorus forms and fractions indicates some of the P entering lakes may have a limited effect on lake productivity. Some P sources, such as land runoff, are often high in particulate P, significant portions of which cannot be utilized in the growth of algae and higher plants. Based on existing information (mostly from Great Lakes studies), potentially bioavailable P in tributaries generally does not exceed 60% of the total P and is often considerably less. Potentially bioavailable P is shown to correspond to the dissolved reactive P (DRP) plus the fraction of particulate inorganic P obtained by extraction with 0.1N NaOH. Whether potentially bioavailable particulate P actually becomes available in a receiving water depends on factors such as the receiving‐water DRP concentration and the position (location) of the particle in the water. A mathematical model, combining two classical modeling approaches, is used to illustrate the importance of positional limitation. Consideration of bioavailability in eutrophication‐control strategies should lead to more cost‐effective management.
A Proposed Classification System for Coal Fly Ash in Multidisciplinary Research
Authors: Roy W. R. , Griffin R. A.
Published: July 2010

A classification system for coal fly ash has been developed to provide the basis for a uniform nomenclature that can be used by investigators in different disciplines to describe samples of coal fly ash. This system is based on chemical composition, hydration pH, and particle‐size distribution. Seven taxonomic groups are generated by the distribution of the sialic (SiO2 + Al2O3 + TiO2), ferric (Fe2O3 + SO3), and calcic (CaO + MgO + Na2O + K2O) components of the fly ashes. Prefixes and suffixes denoting hydration pH, elevated trace and minor element concentrations, and texture are added to the group names to further describe the sample. Classifications of several samples reported in the literature are included and possible applications of the classification system are discussed.
Form and Availability of Copper and Zinc in a Rhodic Paleudult Following Long‐Term CuSO4 and ZnSO4 Applications
Authors: Mullins G. L. , Martens D. C. , Gettier S. W. , Miller W. P.
Published: July 2010

Copper and zinc frequently are incorporated into agricultural soils as fertilizers, pesticides, and waste materials. Field data are needed to determine rates of cumulative Cu and Zn applications that cause yield decreases or accumulations of the micronutrients in plant tissue. This 15‐year field experiment was conducted on a Davidson silty clay (clayey, kaolinitic, thermic Rhodic Paleudult) to determine tolerable levels of Cu and Zn applications for corn (Zea mays L.) and to evaluate soil distribution and form of the applied Cu and Zn. Neither corn grain nor silage yields were affected by 15 years of applications of various levels of Cu and Zn sulfates, which provided a cumulative total of 171.7 kg Cu/ha and 290.4 kg Zn/ha. Copper concentrations in ear leaves sampled at the early silk growth stage generally were unaffected by the Cu applications, whereas Zn concentrations in the ear leaves varied directly with levels of Zn application. Likewise, the Cu concentrations in corn grain were unaffected by the Cu applications, but the Zn concentrations in corn grain were increased by the Zn applications. The DTPA‐extractable Cu and Zn in soils sampled in the 13th year of the study indicated an accumulation of Cu and Zn in the Ap horizon, with little downward movement of the applied Cu and Zn. Sequential extraction data indicated that the applied Cu and Zn were distributed among both potentially plant‐available and ‐unavailable soil fractions.
Spatial and Temporal Patterns of Lead Accumulation in the Forest Floor in the Northeastern United States
Authors: Johnson A. H. , Siccama T. G. , Friedland A. J.
Published: July 2010

In light of the relatively large amounts of anthropogenic Pb deposition from the atmosphere, a regional study of forest floor Pb was undertaken. The current Pb content averages 1.1 ± 0.1 g m−2 and 148 ± 5 µg g−1 of forest floor. Factors that control forest floor Pb levels include precipitation rate, distance from the urban corridor, elevation, proximity to Pb‐emitting industries, forest floor age, and nature of the underlying mineral horizon. Analysis of buried organic horizons from windthrow mounds indicates that the Pb content of the forest floor may have increased five‐ to 10‐fold in the past century.
Application of Sewage Sludge to Soils High in Organic Matter
Authors: King Larry D. , Dunlop Willard R.
Published: July 2010

In a greenhouse study corn (Zea mays L.) was grown in four soils (1.4, 19, 38, and 72% organic matter) that received sewage sludge from Philadelphia, Pa., (PS) at rates to supply 0, 2, 4, and 8 kg Cd/ha. Corn and soybeans (Glycine max. L.) were grown in 1.4 and 19% organic matter (OM) soils that received sewage sludge from Wilmington, N.C., (WS) at rates to supply 0, 2, 4, and 6 kg Cd/ha. The pH of the 1.4% OM soil was adjusted to 6.5 with CaCO3. The higher OM‐content soils received recommended rates of CaCO3 to increase the pH to 5.0–5.5, the desired range for crop production on these soils. Actual resulting pH values were 5.5, 4.9, and 4.6 for the 19, 38, and 72% OM soils respectively.

Corn yields were depressed by PS but enhanced by WS. Soybean yield was enhanced by WS on the 19% OM soil but depressed on the 1.4% OM soils. Both sludges caused increases in concentrations of Cd, Cu, and Zn in the plant tissue, but concentrations were not high enough to be responsible for the observed yield depressions. The PS was more effective in raising Cd and Zn concentrations in plant tissues than was WS. The type of soil had a varying effect on metal concentrations in the plants. The expected reduction in heavy metal uptake with higher soil OM content was confounded by the low pH of the soils with high OM content. The large quantity of OM added via WS masked the effect of soil OM.

Since the bulk densities of the soils varied from 0.45 to 1.35 g/cm3, regression equations describing Cd concentration in corn stover as a function of OM and cation exchange capacity (CEC) were more precise when OM and CEC were expressed on a volume basis and when OM was determined by a procedure designed to estimate humus rather than total oxidizable OM.
The Effect of Cattle Grazing on Nutrient Losses in a Pacific Northwest Setting
Authors: Jawson M. D. , Elliott L. F. , Saxton K. E. , Fortier D. H.
Published: July 2010

Nutrient deliveries in runoff from a cattle‐grazed and a nongrazed (check) watershed were measured for 3 years in the Pacific Northwest to determine nutrient contributions from each. Few runoff events occurred when animals were grazing during the 3‐year study, since this is a winter‐precipitation‐summer‐grazing area.

Total nitogen (TN) losses in runoff from the grazed watershed for water years 1977, 1978, and 1979 ranged from < 1 to 4 kg ha−1 year−1. During the same period TN losses from the check area were < 0.5 kg ha−1. Generally, TN received in precipitation was equal to or greater than N lost in runoff from the grazed watershed. Nitrate‐N levels in the runoff were normally < 1 mg L−1. Total phosphorus (TP) losses in runoff from the grazed watershed during water years 1977, 1978, and 1979 ranged from 0.1 to 1.3 kg ha−1 year−1 and from < 0.1 to 0.17 kg ha−1 year−1 from the check area for the same period. Though grazing appeared to cause an increase in TN, TP, total organic carbon (TOC), chemical oxygen demand (COD), and chloride (Cl) losses in runoff, the quantities would not seem to be a significant threat to downstream water.
Evaluation of Sampling Methods for Detecting Aflatoxin Contamination in Small Test Plots of Maize Inoculated With Aspergillus flavus
Authors: Widstrom N. W. , Wilson D. M. , Mc Millian W. W.
Published: July 2010

Two commercial maize (Zea mays L.) hybrids were grown in 1978 and 1980 to evaluate 13 sampling methods (grain‐sampling‐inoculation combinations) for formation of aflatoxin by Aspergillus flavus Link. The effectiveness of each method in producing uniform, consistent, genotype‐differentiating levels of aflatoxin was determined. Differences in level of aflatoxin contamination did not occur between years, but were highly significant between hybrids and among evaluation methods. Interactions among years, hybrids, and evaluation methods were nonsignificant. Mid‐ear inoculations with a knife at 20 d after full silk were more effective than were needle inoculations at the ear‐tip in eliciting high and consistent aflatoxin levels. Kernels from the immediate inoculated area of the ear or from inoculated segments of ears had the highest levels of aflatoxin contamination. Kernels from entire ears, or portions of ears, that appeared clean of fungus infection contained lower levels of aflatoxin contamination. Kernels from entire ears contained low to intermediate levels of aflatoxin, but the differences in levels seem adequate for detecting differences between genotypes. Treatments with low aflatoxin levels were generally associated with the highest coefficients of variation, although variances per se could not be positively associated with aflatoxin concentrations of the various methods.
Soil Adsorption of Cadmium From Solutions Containing Organic Ligands
Authors: Elliott H. A. , Denneny C. M.
Published: July 2010

The adsorption of cadmium (Cd) from aqueous solutions containing acetate (Ac), oxalate (Ox), nitrilotriacetate (NTA) and ethylenediaminetetraacetate (EDTA) onto three soils from the northeastern United States was investigated. Experimental parameters were adjusted so that, under typical field pH conditions, roughly half of the soluble Cd was present as Cd2+ while the other half, depending on the system, existed as Cd2+, CdAc+, CdOx0, CdNTA−, or CdEDTA2−, Organic complexation reduced, or had little perceptible effect on, Cd adsorption when compared to the unbound Cd system. In general, the ability to reduce Cd retention followed the trend: EDTA > NTA > Ox ≈ Ac. Since the strength of the Cd‐ligand stability constants follows the same order, it suggests that competition for the metal ion between the soil exchange sites and the added organic ligands is important in explaining the observed behavior. Despite the formation of cationic complexes (CdAc+), the presence of Ac interfered with Cd uptake under acidic conditions. This was apparently due to competitive adsorption of the free un‐ionized acetate species on the soil surface. The ability of organic complexants to influence Cd adsorption decreased with increasing suspension acidity because of preferential binding of the ligands to metals (Fe3+ and Al3+) released by the acid‐catalyzed dissolution of soil components. The coexistence of soluble metal chelators with heavy metals in a land‐applied waste may increase the mobility of the metals in the soil, the effect being more pronounced in neutral or alkaline soils and for ligands that form stable, nonadsorbing complexes with the metals.
Humic Substances in Landfill Leachates: I. Humic Acid Extraction and Identification
Authors: Artiola‐Fortuny Juan , Fuller Wallace H.
Published: July 2010

A useful extraction for humic acid from anaerobic municipal solid‐waste landfill leachate is presented. Extraction was accomplished by adding NaOH pellets to give a 0.57N NaOH solution under an N2 atmosphere. The separation of the humid and fulvic acid fractions was carried out using Matricel type filters (0.45‐µm pore size diam). The infrared characterization of leachate humic acids was markedly improved in time and sample‐size‐requirement reductions by using a Matricel filter made out of a PVC copolymer as a support for these acids. The results obtained compared very favorably with the infrared KBr pellets. The infrared spectra of leachate humic acids proved to be similar to the lake‐ooze humic acid spectra reported by Stevenson and Goh (1971).

Humid substances represent > 60% of the total organic C found in anaerobic landfill leachates. Fulvic acid predominates in young unstable leachates, and decreases in concentration with age. Humic acids increase with the age of the leachates, eventually decreasing as the leachate becomes more stable and diluted.
Plant Availability of Phosphorus and Heavy Metals in Soils Amended with Chemically Treated Sewage Sludge
Authors: Gestring W. D. , Jarrell W. M.
Published: July 2010

The objective of this study was to evaluate the effect of sludge chemical treatment (Al3+, Fe3+, and Ca2+) on P and heavy metal availability in sludge‐amended soils.

Municipal sewage sludge treated with the chemicals Al2(SO4)3, FeCl3, or Ca(OH)2, along with untreated sludge and monocalciumphosphate (MCP; Ca(H2PO4)2·H2O) fertilizer, were applied to acid, neutral, and alkaline soils at rates equivalent to 83, 125, 250, and 500 kg P ha−. Swiss chard (Beta vulgaris) was grown in these soils to maturity with leaf samples taken 38, 54, and 70 d after planting. Swiss chard yields were determined and plant tissue analyzed for P, Zn, Fe, Mn, Cd, Ni, and Pb. Soil samples were analyzed for HCO3‐extractable P and pH.

Zinc and Manganese concentrations in plant tissue were significantly higher (P <0.05) for the Al‐treated sludge at an application rate of 500 kg P ha−1 in the acid soil. Plant Cd levels were significantly higher (P <0.01) for the Al‐treated sludge at application rates of 250 and 500 kg P ha−1 in the acid soil. The increased plant levels of Zn, Mn, and Cd appear to be the result of a lower soil pH produced upon the addition of Al‐treated sludge. No significant differences in Fe, Ni, and Pb concentrations were observed in the plant tissue for any of the treatments or application rates.

Bicarbonate‐extractable P was greater where MCP was applied than where any sludge was applied in the acid and alkaline soils; however, no discernible trends in P uptake by the chard were observed for any of the fertilizer treatments or application rates. Phosphorus was equally available from the sludges and MCP in the acid and alkaline soils.
Relationships Among Injury, Growth, and Yield Responses of Soybean Cultivars Exposed to Ozone at Different Light Intensities
Authors: Heagle Allen S. , Letchworth Michael B.
Published: July 2010

Four soybean cultivars (Glycine max (L.) Merr. cv. Forrest, Davis, Ransom, and Bragg) differing in foliar sensitivity and shoot weight response to O3 during vegetative growth were exposed to O3 from the seedling stage to maturity to determine if the yield response correlated with the vegetative response. Neither the foliar injury nor the vegetative shoot weight response of cultivars to O3 allowed reasonable prediction of the cultivar yield response to O3. This inadequacy may relate to differences in cultivar tolerance. Bragg, with moderate amounts of O3‐induced injury and with decreased growth, yielded as well as the controls. Davis, with moderate amounts of O3‐induced injury and decreased growth, yielded 34% less than the controls. The four cultivars were grown in open‐top field chambers with different degrees of shading to determine whether light intensity would alter their response to O3. Light intensity in nonshaded open‐top chambers was 9% less than that in an open field; chambers with shade cloth covering the sides or tops decreased light intensity by 15 and 19%, respectively. The shade treatments did not change overall yield response to O3 or the relative cultivar yield response to O3.
Cadmium‐Enriched Sewage Sludge Application to Acid and Calcareous Soils: Effect on Soil and Nutrition of Lettuce, Corn, Tomato, and Swiss Chard
Authors: Mahler R. J. , Bingham F. T. , Page A. L. , Ryan J. A.
Published: July 2010

Eight soils with pH values ranging from 4.8 to 7.8 were amended at a 1% rate with a municipal sewage sludge containing variable amounts of CdSO4. The resultant concentrations of Cd in the soils ranged from 0.1 to 160 µg Cd/g. To observe the interactive effects of soil pH and Cd on elemental composition of plants, lettuce (Lactuca sativa var. Longifolia), tomato (Lycopersicon esculentum Mill.), sweet corn (Zea mays L.), and Swiss chard (Beta vulgaris var. cicla) were grown for 7 weeks in a greenhouse in pots containing the treated soils. Comparison of Cd availability to lettuce, Swiss chard, corn, and tomato grown on acid soils with that on calcareous soils revealed less Cd uptake by plants under alkaline soil conditions.

The concentrations of Cd in the saturation extracts of the calcareous soil groups were significantly greater than those of the acid soil groups; however, this was not reflected in greater plant uptake of Cd from the calcareous soils.

Cadmium additions to the soils generally decreased Zn and Mn concentrations in saturation extracts in calcareous soils. These decreases were reflected in reduced concentrations of Zn and Mn in leaves of the test crops. The relationships between saturation‐extract compositions of Cd, Zn, and Mn and their plant compositions were found to be different for the acid as compared with the calcareous soil groups.
The Extent and Nature of Rainfall‐soil Interaction in the Release of Soluble Chemicals to Runoff
Authors: Ahuja L. R. , Lehman O. R.
Published: July 2010

Experiments were conducted with a simulated rainfall on boxes of three different soils (Ruston fine sandy loam, Ruston loam, and Parsons clay), prewetted with a bromide (4,000 ppm Br) solution. The bottom of the soil boxes (100 cm long by 15 cm wide by 10 cm deep) was either an impervious plate that allowed no downward infiltration through the soil during the rainfall, a pervious plate that allowed free infiltration, or a pervious plate covered with a thin layer of soil‐slurry, which allowed infiltration at a reduced level. In all the soils, Br concentrations in runoff from impervious‐base boxes were one to two orders of magnitude higher than in runoff from pervious‐base boxes. The concentrations in slurry‐base boxes were intermediate. This result and the shape of the concentration‐time curves showed that the concept of an effective complete mixing depth of rainwater and soil solution used in modeling the release of chemicals‐to‐runoff is not strictly valid. However, the concept may be applied as an approximation to the data from pervious boxes. Bromide concentrations of the soil in the impervious‐base boxes at the end of 1‐h rainfall events (6.8 cm of rain) showed that the Br was lost to runoff from as great as the 2.0‐cm depth. The amount released, however, decreased with depth. It is suggested that the transfer of chemical from below a thin soil surface layer may be due to pumping action of, or turbulence generated by, the raindrop impacts, and may be considered as an accelerated‐diffusion process. As a simplified approach, the mixing zone concept was modified and tested by incorporating an exponential decrease in the degree of mixing with depth, and a piston displacement of soil solution by infiltration. This approach seemed adequate as a first‐order approximation. The results suggest that clay‐pan soils, wet areas in a watershed, and tillage practices that increase permeability of the soil‐surface layer relative to that of the layer below will greatly increase the loss of soil chemicals to runoff.
The Impact of an Urban‐Industrial Area on Deciduous Forest Tree Growth
Authors: Mc Clenahen J. R.
Published: July 2010

Factors affecting the height‐growth of white ash (Fraxinus americana L.) and northern red oak (Quercus rubra L.) trees in natural stands were studied within the airshed of an industrial city in central Ohio. Stepdown multiple regression analysis was used to determine the effect of tree age, topography, precipitation, and physical and chemical soil properties on cumulative height‐growth between 1930–76, which included an era of major urban and industrial expansion. Expressions of distance from the city and an index of relative pollutant exposure (RPE), derived in part from the frequency of airflow from the city during the growing season, were also tested as independent variables indicative of relative pollutant dose. Eleven and thirteen significant variables in the final white ash and red oak models explained 63 and 93% of the variation in height‐growth, respectively. Distance from the city and RPE were significant in the models of both species. Significant interactions of these variables with tree age indicated that growth of youngered oaks was more strongly depressed by increasing RPE than was that of older trees; growth of younger, but not older, white ash increased with distance from the city. Red oak growth was unexplainably predicted to be greater nearer the city. Holding tree age and site variables at their means, height‐growth was estimated by the regression models for actual RPE at selected distances and directions around the city. Isopleths constructed from these estimates showed an area of reduced growth northeast of the city in the prevailing wind direction for both species. It appears from this study that height‐growth of forest trees can be measurably depressed as a result of urban influences probably relating to air pollutant exposure.
Adsorption and Degradation of Phenol at Low Concentrations in Soil
Authors: Scott H. D. , Wolf D. C. , Lavy T. L.
Published: July 2010

The adsorption and microbial degradation of labile organic chemicals by soil may be influenced by their concentrations in solution. The objectives of this study were to determine the effects of relatively low concentrations of phenol on its adsorption by soil surfaces and degradation by microorganisms, and the variability associated with the adsorption and degradation by two soils. Phenol, an antimicrobial agent at higher concentrations, was equilibrated with Captina (Typic Fragiudult) and Palouse (Ultic Haploxeroll) silt loams at concentrations ranging between 10−6 (94 µg/kg) and 10−9M (94 ng/kg) and at equilibration times ranging to 24 h.

Microbial degradation of phenol increased both the sampling variability and the apparent amount adsorbed by the two soils. For sterile soil the adsorbed concentration, S, was more variable than the solution concentration, C, For nonsterile soil, the variability of both S and C increased, with C more variable than S. Microbial decomposition of phenol caused the Freundlich K values to increase to a maximum at 12 h of equilibration. Little or no effect was found on the Freundlich N. Degradation coefficients were higher, and as a result, half‐lives were shorter in the Captina soil than in the Palouse. These results showed that K and N of phenol in nonsterile soil could be estimated by extrapolation to time zero.
Soluble Reactive Phosphorus Measurements in Lake Water: Evidence for Molybdate‐enhanced Hydrolysis
Authors: Tarapchak Stephen J.
Published: July 2010

Measurements of ortho‐phosphate (PO4‐P) concentrations in natural waters obtained by molybdenum blue methodology are based on the assumption that molybdate (Mo) complexes only with PO4‐P (in the absence of arsenate and silicate interference) to form the reductant‐sensitive complex 12‐molybdophosphoric acid (12‐MPA). The hypothesis that Mo causes or accelerates PO4‐P release from bound sources or forms reductant‐sensitive complexes with organic compounds (organic‐PO4‐Mo) was tested by exposing filtered Lake Michigan water to acid, acid plus Mo simultaneously, and Mo, respectively, before measuring PO4‐P by the Chamberlain‐Shapiro extraction method. Not only does Mo accelerate hydrolysis in the presence of acid, but it also either causes hydrolysis or forms organic‐PO4‐Mo before samples are acidified. Although the relative amounts of 12‐MPA and organic‐PO4‐Mo formed in lake water cannot be assessed quantitatively, a major fraction of the blue color formed during routine analysis by this or by similar methods apparently is not the product of acid hydrolysis, but may also be due to reduction of organic‐PO4‐Mo. Future developments in molybdenum blue methodology aimed at minimizing hydrolysis must consider the sequence of reagent additions and Mo, as well as acid, contact times.
Acid Rain and Soil Microbial Activity: Effects and Their Mechanisms
Authors: Killham K. , Firestone M. K. , Mc Coll J. G.
Published: July 2010

In this investigation, our aim was to determine if acid rain affects soil microbial activity and to identify possible mechanisms of observed effects. A Sierran forest soil (pit 6.4) planted with Ponderosa pine seedlings was exposed to simulated rain (pH 2.0, 3.0, 4.0, and 5.6) with ionic composition reflecting that found in northern California, corresponding to 15 cm of precipitation over a 12‐week period. After exposure, the soils were collected in two samples (top 1 cm and 4 to 5 cm), which were assayed separately for respiration and enzyme activities (urease, phosphatase, dehydrogenase, and arylsulfatase). Changes in microbial activity were most significant in surface soils. Only the pH 2.0 input caused inhibition of both respiration and enzyme activities. The overall microbial response to the pH 3.0 and 4.0 acid regimes was one of stimulation, although the response of individual enzymes was more varied. In surface soils receiving the pH 3.0 input, for example, urease activity was unaffected while arylsulfatase and phosphatase were increased and decreased respectively. Therefore, individual microbial processes will have different sensitivities to acid rain. Although changes in C‐availability in the exposed soils are documented, changes in the supply of N are evaluated as the major mechanism through which simulated acid rain affects soil microbial activity.
Behavior of Chromium in Soils: VII. Adsorption and Reduction of Hexavalent Forms
Authors: James Bruce R. , Bartlett Richmond J.
Published: July 2010

Based on adsorption studies with Fe(OH)3, Cr(OH)3, and soils, 10 mM K‐phosphate buffered at pH 7.2 was found to be adequate for characterizing exchangeable Cr(VI). The quantity of Cr(VI) removed from solution by 19 A and 19 B horizon soils from the northeastern United States was partitioned into two fractions, based on the amount of soil‐Cr extracted with the phosphate buffer. The fraction removed by the buffer was termed “exchangeable;” that retained by the soil was termed “nonexchangeable.” The nonexchangeable Cr(VI) not recovered by phosphate had been either reduced to an insoluble form of Cr(III), or had been precipitated or very tightly adsorbed by the soil as anionic Cr(VI).

Of 20 µmol/100 g soil (23 kg/ha) Cr(VI) added, an average of 7.2 was removed by the unlimed 38 soils (mean pH 5.4). Of this quantity, 4.8 µmol were exchangeable by phosphate. Surface soils generally removed less Cr(VI) than B horizons (5.8 vs. 8.6 µmol/100 g), and the proportion of Cr(Vi) removed in phosphate‐exchangeable form also was lower. Liming to pH 7 decreased the average quantity of Cr(VI) removed by the soils to 2.6, with exchangeable and nonexchangeable forms each accounting for about 50% of the total.

Sulfate and phosphate added with Cr(VI) to two A and two B horizon soils decreased Cr(VI) removal by the soil, with phosphate having a greater effect than sulfate. Although liming decreased Cr(VI) removal by the soils, even less Cr(VI) was held in exchangeable or nonexchangeable form in limed treatments containing the competing anions.

Gallic acid rapidly reduced Cr(VI) held by soil colloids in exchangeable form except in limed samples of spodic horizons and a Hydric Dystrandept Ap, all high in amorphous, organically complexed Al and Fe sesquioxides.
Effect of Copper Levels in Swine Manure on Corn and Soil
Authors: Sutton A. L. , Nelson D. W. , Mayrose V. B. , Kelly D. T.
Published: July 2010

Effects of Cu levels in liquid swine manure were studied for 5 y on corn (Zea mays L.) and Crosby silt loam soil (Aerie Ochraqualfs). Pigs housed on slatted floors above pits were fed 16% crude protein corn‐soy diets with either 0, 125, or 250 mg/kg of supplemental Cu as CuSO4. Swine manure (3.2–5.2% dry matter) collected from the anaerobic pits was surface‐applied annually to soil at rates of 90, 180, and 270 t/ha for 4 y. No manure was applied the fifth year to determine the effects of residual nutrients. Check and inorganic fertilizer (168 kg N/ha, 56 kg P/ha, 112 kg K/ha) treatments were also included.

Supplemental CuSO4 in the swine diet increased Cu levels in manure and consequent Cu application to the soil. Copper‐enriched manure increased the 1N HCl‐extractable Cu in the upper portion of the soil profile (0–31 cm), but not at lower depths. High Cu applications from manure did not elevate plant leaf Cu concentrations, and did not adversely affect corn yields.

Corn yields and leaf composition were not affected by rate of manure application since crop nutrient requirements were exceeded. Applied K and NO3−‐N moved downward in the soil profile, but a majority of these nutrients in soil were depleted by the end of the study. In contrast, applied P accumulated in the upper soil profile (0–31 cm).

Application of liquid swine manure from pigs fed a high level of CuSO4 over a 4‐y period at the rates used in this study did not lead to excessive soil accumulation or enrichment of corn tissue with Cu.
Simultaneous Determination of Nitrate, Chloride, Sulfate, and Phosphate in Natural Waters by Ion Chromatography
Authors: Tabatabai M. A. , Dick W. A.
Published: July 2010

Simultaneous analysis of anions in water samples is needed. Studies to evaluate the Dionex Model 10 Ion Chromatograph (IC) for simultaneous determination of NO3−, Cl−, SO42−, and PO43− in water samples, including soil extracts, showed that the results by the IC method agreed closely with those obtained by the steam‐distillation method for NO3−, colorimetric method using mercuric thiocyanate and ferric ammonium sulfate for Cl−, reduction and colorimetric determination as methylene blue for SO42−, and colorimetric molybdenum blue method for PO43−. The IC method is based on separation of the anions by a separator column containing Dionex low‐capacity anion‐exchange resin in the HCO3− form and on converting the various anions to their corresponding acids by a suppressor column containing a strong acid cation‐exchange resin in the H+ form. A solution 3.0 mM NaHCO3 + 2.4 nM Na2CO3 is used as the eluent, and electrical conductivity is used as the mode of detection. The method is precise and accurate, and can detect as little as 0.1 mg/L of NO3−‐N, Cl−, SO42−‐S, or PO43−‐P in water samples. The coefficient of variation ranged from 0.44 to 8.6% for NO3−‐N, from 0.14 to 4.3% for Cl−, from 0.13 to 1.1% for SO42−‐S, and from 0.55 to 8.6% for PO43−‐P. With the IC method, the 4 anions indicated can be determined simultaneously in 2 mL of water in approximately 10 min.
Laboratory Composter for Simulation Studies
Authors: Sikora L. J. , Ramirez M. A. , Troeschel T. A.
Published: July 2010

A self‐heating laboratory composter comprised of a covered, double‐walled, insulated tank containing water, an air‐tight cylinder submerged in the tank, an inner screen mesh cylinder that held the organic material, a heater‐circulator, and a differential temperature control system was built and tested for use in studies simulating the biochemical changes that occur during composting. A mixture of raw, limed sewage sludge and woodchips was composted, and the weight‐loss data obtained were similar to that from the pilot plant composting facility at Beltsville, Md. The mixture lost 33% of its wet weight, and 9% of its dry weight during 28–50 d of composting. Six to ten percent of the total N was lost. There were two major temperature peaks, which correlated with CO2 increases. Peak NH3 evolution occurred when CO2 evolution decreased. All preliminary data indicate that the laboratory composter provides a comparable simulation of a large composting facility.
Microorganisms and Higher Plants for Waste Water Treatment
Authors: Wolverton B. C. , Mc Donald R. C. , Duffer W. R.
Published: July 2010

Batch experiments were conducted to compare the waste water treatment efficiencies of plant‐free microbial filters with filters supporting the growth of reeds (Phragmites communis), cattail (Typha latifolia), rush (Juncus effusus), and bamboo (Bambusa multiplex). The experimental systems consisted of two components in series. The first component was an anaerobic settling‐digestion container. The second was a “nonaerated” trough filled with rocks, decreasing from large rocks (up to 7.5‐cm diam) at the bottom, to pea gravel (0.25‐ to 1.3‐cm diam) at the top. The plant‐free microbial filter was equally effective in carbonaceous BOD5 (5‐d biochemical O2 demand) removal. The vascular aquatic plant series enhanced ammonia removal, and consequently improved nitrogenous BOD5 removal. Under the conditions of these experiments, raw sewage with initial BOD5's of 100 mg/L can be upgraded to meet secondary standards with 6 h in component 1, and 6 h in a plant‐free filter or filter using cattail, rush, or reed. When initial BOD5's are approximately 450 mg/L, 24 h in component 1, 29 h in a reed filter are required to meet secondary standards. Total N removal studies were conducted, which demonstrated that a reed system is capable of removing NO3‐N and NH3‐N simultaneously, probably through a common NO2‐N intermediary, then to N2. Overall, the reed system was superior to all others evaluated in this research project.
Removal of Nitrogen and Phosphorus From Waste Water in a Waterhyacinth‐Based Treatment System
Authors: De Busk T. A. , Williams L. D. , Ryther J. H.
Published: July 2010

The importance of waterhyacinth plant material (living and detrital) as a sink for nitrogen (N) and phosphorus (P) was evaluated in a waste water treatment system in south Florida. The treatment system consisted of four ponds (0.1 ha each) from which plants were harvested, and one pond (0.2 ha) from which plants were not harvested. Nitrogen and phosphorus were removed in the plant standing crop at higher rates in the harvested ponds (362 and 115 mg m−2 d−1, respectively) than in the non‐harvested pond (55 and 15 mg m−2 d−1, respectively). However, immobilization of N and P as plant detritus in the sediment was less in the harvested ponds (3 and 1% of standing crop assimilation, respectively) than in the non‐harvested pond (33 and 13% of standing crop assimilation). With the exception of N in the nonharvested pond, estimates of nutrient removal by the waterhyacinth standing crop and detritus from 4 May–4 Aug. 1981 were similar (within 35 mg N or P m−2 d−1) to the observed nutrient removal from the waste water. Denitrification accounted for 92% of the N removed from the non‐harvested pond. On an areal basis, approximately 2.4 times more N was removed by denitrification in the non‐harvested pond than was assimilated by waterhyacinth growth in the harvested ponds (875 vs. 362 mg N m−2 d−1).

Mean total N removal from the complete system resulted in an 87% reduction, from 9.96 to 1.25 mg/L. Total P was reduced only 10%, from 4.68 to 4.23 mg/L.
Impact of Ozone on Soybean Yield
Authors: Kress L. W. , Miller J. E.
Published: July 2010

Field‐grown soybeans [Glycine max (L.) Merr., cv. Corsoy] were exposed to O3 for 7 h daily (0900–1600 CST) for 56 d in open‐top chambers. The air in the chambers was either charcoal‐filtered or non‐filtered, with various constant amounts of O3 added. The randomized block design incorporated four replicates of six treatments: no chamber (0.042 ppm O3 seasonal 7‐h average); chamber with charcoal‐filtered air (0.022 ppm O3); and chambers with non‐filtered air plus added O3 to provide concentrations of 0.042, 0.064, 0.089, and 0.115 ppm. A linear reduction in seed weight per plant with increasing ozone dose (b (slope) = −87.18) was significant (P = 0.01), and yields were reduced 5, 23, 39, and 52% for the 0.042, 0.064, 0.089, and 0.115 ppm O3 treatments, respectively, compared with the 0.022 ppm treatment. Significant (P = 0.01) linear reductions were also noted for filled pods per plant (b = 184.4), seeds per filled pod (b = −0.9955), weight per seed (b = −0.3794), and percent oil content (b = −12.33). Significant (P = 0.01) linear increases were noted for unfilled pods per plant (b = 58.11) and percent protein content (b = 20.58). A comparison of the open plots with the nonfiltered air chamber plots provided with the same concentration of O3 revealed no significant chamber effects.
Fractionation of Phosphorus in Sludge‐Affected Soils
Authors: Chang A. C. , Page A. L. , Sutherland F. H. , Grgurevic E.
Published: July 2010

Phosphorus accumulated in sludge‐treated soils was chemically fractionated by a sequential extraction procedure. Samples used for the study were obtained from experimental plots of a sludge land application site, where composted sludges at rates 0, 22.5, 45, and 90 t ha−1 y−1, and liquid sludges at rates of 0, 3.75, 7.5, and 15 cm/y have been applied for 5 y. There were also experimental plots whose liquid sludge treatments were terminated after 3 y. The experimental field was cropped with winter barley (Hordeum vulgare) after the sludge applications.

In soils not treated with sludges, the Ca‐bound P accounted for 50–60% of the total P. An accumulation of Al‐ and Fe‐bound P occurred in all sludge‐treated soils. In the top 15 cm of surface soil, after 5 y of composted sludge treatment at a rate of 90 t ha−1 y−1 (1980), the Al‐ and Fe‐bound P was > 60% of the total P. Concentrations of water‐soluble P in sludge‐treated soils also increased. There were indications that the organically bound P in sludge‐treated soils was the most likely form to leach. Three years after the termination of sludge applications, there was little change in the distribution pattern of sludge‐borne P in the soil profile.
Assessing the Suitability of Soils With Macropores for Subsurface Liquid Waste Disposal
Authors: Bouma J. , Belmans C. , Dekker L. W. , Jeurissen W. J. M.
Published: July 2010

The capacity of soils to accept and purify liquid waste can be manipulated by using different application regimes. The associated transient soil physical conditions, which govern purification processes, were measured experimentally in soil columns and in situ, and were predicted by simulation in three soils of which two had macropores.

Measurements of pressure heads, outflow rates, and breakthrough curves were made following intermittent liquid applications of 2 cm d−1. Rapid breakthrough and short‐circuiting, which were observed in the soils with the macropores, could be reduced by adding a light crust.

Predictions involved computer simulation of pressure heads during infiltration and redistribution, and of outflow rates in the columns. Good agreement was found between measured and calculated values, but only when the model for soils with macropores was modified to include a subprogram for macropore flow. Simulation required hydraulic conductivity (K) at and near saturation, which was obtained with a modified crust test procedure.

Use of the simulation program allows the prediction of soil physical conditions for a range of application rates in terms of ponding times and drainage rates, which affect purification and clogging. Measurement of breakthrough curves yields travel times as a function of application rates. Optimal application rates can be estimated by considering these two types of data, as is illustrated with an example. This approach is preferred over the current procedure using a single hydraulic parameter.
Application Mode and Alternate Cropping Effects on Atrazine Losses From a Hillside
Authors: Hall J. K. , Hartwig N. L. , Hoffman L. D.
Published: July 2010

External drainage losses of atrazine (2‐chloro‐4‐[ethylamino]‐6‐[iso‐propylamino]‐s‐triazine) were evaluated at two application rates, applied preemergent, and pre‐plant‐incorporated on a hillside where corn (Zea mays L.) was planted with and without oats (Avena sativa L.) as a strip crop at the slope base. The cropping pattern had the most striking influence on soil, water, and atrazine transport in a growing season where a 100‐y frequency storm occurred during June. Statistical covariance analysis revealed that nearly 100% of the time, total atrazine residue losses in external drainage and soil sediment were most strongly related to the number of days from herbicide application to each erosion event.

The small grain strip or buffer zone reduced water and soil losses by 66 and 76%, respectively, compared with nonstripped areas, during 11 erosion events. Atrazine losses of 3.5 and 0.33% of that applied (2.2 kg/ha) were recorded in the absence and presence of an oat strip, which represented a 91% reduction in herbicide loss with strip cropping. At the 4.5 kg/ha application rate, herbicide losses were reduced by 65% in the stripped areas compared with the nonstripped areas. Minimal pre‐plant incorporation of atrazine residues with the soil surface also significantly reduced residue loss with each cropping pattern. Using nonstripped, preemergent treated areas as a reference, pre‐plant incorporation of atrazine with strip cropping reduced total atrazine losses by 91 and 87% at the two respective application rates, and allowed only 7 g/ha of atrazine loss at each rate. Therefore, a conventional tillage‐management system combining a minimal surface‐blending of atrazine residues with strip cropping provided soil, water, and chemical residue retention equivalent to that achieved in reduced‐tillage crop management and controlled weeds effectively.