bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical Properties of Metal‐Humic Acid Fractions of a Sewage Sludge‐Amended Aridisol
Authors: Senesi Nicola , Sposito Garrison , Holtzclaw Kenneth M. , Bradford Gordon R.
Published: July 2010

Humic acid (HA) was extracted from a Domino soil (Xerollic Calciorthids) cropped with barley (Hordeum vulgare L.) and sorghum [Sorghum bicolor (L.) Moench] in experimental plots that received applications of sewage sludge for 4, 5, 6, or 7 yr at rates of 0,22.5, 45, or 90 Mg ha−1 yr−1. The HA samples were characterized chemically by elemental and functional group analyses, total trace metal content, infrared (IR), and electron spin resonance (ESR) spectroscopy. As compared to the nonamended Domino (Xerollic Paleorthids) soil HA, the highest sludge‐amended soil HA was extracted in higher yields and had higher N and S contents, lower C/N molar ratios, higher total acidity and phenolic OH content, lower organic free radical content, and higher relative intensity of the amide I and amide II IR absorption bands. These differences are believed to be caused by the incorporation of components typical of the applied sludge organic fraction into the soil HA, i.e., proteinaceous materials, sulfur‐containing compounds, and phenolic components. The HA also exhibited a well‐defined selectivity in respect to trace metal adsorption/desorption. Copper, Ni, Zn, Fe, and Cr were adsorbed strongly onto readily available sites, or through exchange with more weakly adsorbed trace metal ions (Mn, V, Ti, and Mo). However, the soil HA tended to reach metal saturation at the highest sludge application rates. The ESR analysis showed the presence of indigenous Cu2+, Fe3+, and VO2+‐HA complexes in all HA samples. These complexes had similar chemical and structural properties, and were concluded to represent the speciation of the metals in association with HA. In general, the impact of the organic constituents in fresh sludge on the soil HA appeared to be mitigated somewhat by the continual tendency of soil organic matter to attain equilibrium, whereas the metal‐organic portion of the soil HA was significantly affected by sludge application.
Environmental Fate of Picloram Used for Roadside Weed Control
Authors: Watson V. J. , Rice P. M. , Monnig E. C.
Published: July 2010

The herbicide picloram (4‐amino‐3,5,6‐ trichloro‐2‐pyridine carboxylic acid) was applied to control spotted knapweed (Centaurea maculosa Lam.) in the northern Rockies to determine persistence in soils and vegetation, losses by photodegradation, rainfall induced migration, and potential contamination of surface and groundwater. Two sites were selected to represent best case and worst case conditions (within label restrictions) for on‐site retention of picloram. A valley bottom terrace was treated with 0.28 kg/ha of picloram in the spring of 1985, and sampled over the following 445 d. In the spring of 1986, 1.12 kg/ha of picloram was applied to both sides of a minimal construction logging road extending 4 km along a stream (102 to 815 m3) that drains agranitic upper mountain watershed. Of the 17.1 km2 watershed, 0.15% (2.5 ha) was sprayed. Vegetation, soils, surface water, and groundwater near the road were sampled during the 90 d following application. At the valley bottom site, 36, 13, and 10.5% of the picloram applied persisted after 90, 365, and 445 d, respectively. At the mountain watershed site, 78% persisted after 90 d, and picloram was not detected in the surface or groundwaters during the 90 d following application. Depending on the timing of delivery, as little as 1% or less of the application could have been detected after delivery to the stream. Loss by photodegradation during the first 7 d after treatment was important at both sites.
Effects of Cations on Complexation of Naphthalene by Water‐Soluble Organic Carbon
Authors: Traina Samuel J. , Spontak Donna A. , Logan Terry J.
Published: July 2010

The effects of cation type (Na, Ca, or Al), pH, and stoichiometric ionic strength (Is) on the complexation of naphthalene (in ClO−4 media) by water‐soluble soil organic matter extracted from a muck soil (Euic, mesic Typic Medisaprist) were investigated with a fluorescence quenching technique. Decreases in the intrinsic fluorescence of the naphthalene, resulting from additions of water soluble soil organic matter (0–28 mg L−1 C expressed as water‐soluble organic carbon or WSOC) were used to calculate conditional naphthalene‐WSOC stability constants (cKoc) for each of the electrolyte systems investigated. For all cases, increased aqueous concentrations of WSOC caused an increase in the formation of naphthalene‐WSOC complexes. Changes in pH value from 1.5 to 7.3 (in the presence of 0.05 mol L−1 NaClO4) and changes in Is from 0.05 to 0.5 mol L−1 [in the presence of either Ca(ClO4)2 or Al(ClO4)3] had no effect on the binding of naphthalene by WSOC. In homoionic systems of either NaClO4, Ca(ClO4)2, or Al(ClO4)3) (for Is = 0.05 mol L−1), the formation of naphthalene‐WSOC complexes decreased in the order Na = Ca > Al. The effect of Al on the binding of naphthalene by WSOC may have resulted from changes in the physical, polymeric structure of WSOC molecules caused by the presence of Al as a counter ion.
Sediment and Nutrient Losses from an Unimproved, All‐Year Grazed Watershed
Authors: Owens L. B. , Edwards W. M. , Van Keuren R. W.
Published: July 2010

A common practice for grazing land in the humid, eastern USA is continuous grazing with little or no fertilizer use. Concentrations and transport of nutrients from a 28‐ha unimproved grassed watershed were assessed in east‐central Ohio for 2 yr without the presence of livestock, for 3 yr with a 17‐cow beef (Bos taurus) herd grazing during the summer months only, and for an additional 6‐yr period with all‐year grazing with hay being brought in for winter feed. Nutrient concentrations remained low during all three grazing levels. An exception was K concentration, which increased with all‐year grazing. Concentrations of NO3‐N, mineral‐N, P, Ca, Mg, Na, and Cl were similar to or less than the concentrations from a nearby 17.7‐ha wooded watershed that contained no pastured areas and received no agricultural inputs. Nutrient concentrations showed no consistent seasonal variation. Concentrations of organic‐N, total organic C and sediment increased with increased grazing pressure. Greatest sediment concentrations and transport rates generally occurred during July and August regardless of grazing system. Largest monthly average sediment concentrations were 0.8, 1.3, and 3.2 g/L for the three systems, respectively; annual sediment losses were 0.2, 1.2, and 2.1 Mg/ha, respectively. All‐year cattle grazing/feeding on an unimproved pasture in this area would not be expected to produce degradation of stream water quality from nutrient concentrations or transport.
Effects of Air Filtration on Concentration and Deposition of Gaseous and Particulate Air Pollutants in Open‐Top Field Chambers
Authors: Bytnerowicz A. , Olszyk D. M. , Dawson P. J. , Morrison L.
Published: July 2010

Concentrations of gaseous and particulate air pollutants, and deposition fluxes of NO−3, SO2−4, and NH+4 ions to branches of California lilac (Ceanothus crassifolius Torr.), Coulter pine (Pinus coulteri D. Don.), ponderosa pine (P. ponderosa Dongl. ex P. & C. Lawson), nylon filters, and paper filters were measured in open‐top field chambers with different filtration materials and in chamberless outside plots. Concentrations of O3 inside charcoal‐filtered (CHARCOAL) chambers were reduced to 18 to 24% of the outside concentrations, while concentrations of NO2 were reduced to about 42 to 67%, with a simultaneous increase of NO concentrations. Concentrations of these gases in the chambers equipped only with the fiberglass dust filter (DUST 1) and fiberglass dust filter plus heavy duty strainer mat (DUST 2) were similar to those in the outside plots. On the average, concentrations of NO−3 (sum of particulate nitrate and nitric acid vapor) in the CHARCOAL chambers were reduced to about 40% of the outside levels, while concentrations of particulate SO2−4 and NH+4 (sum of particulate NH+4 and NH3) were reduced to about 84 and 79%, respectively. In the DUST 1 and DUST 2 chambers, concentrations of NO−3 were reduced to about 73% of the outside levels, and concentrations of SO2−4 and NH+4 to about 90 and 92%, respectively. Effects of different air filtrations were more evident for deposition fluxes to plant and surrogate surfaces. On the average, in the CHARCOAL chambers, deposition fluxes of NO−3, SO2−4, and NH+4 to the surfaces were reduced to 21, 38, and 26% of the outside values, respectively. In the DUST 1 and DUST 2 chambers, deposition fluxes of NO−3, SO2−4, and NH+4 were reduced to about 50, 56, and 75% of the outside levels, respectively. Deposition fluxes of the studied ions to plants were much lower than to nylon and paper filters. The results of this study add important information for open‐top chamber studies, especially if long‐term effects of ambient concentrations of air pollutants on vegetation are considered.
Transformation and Mineralization of Metribuzin in Surface and Subsurface Horizons of a Mississippi Delta Soil
Authors: Moorman T. B. , Harper S. S.
Published: July 2010

The rates of degradation and mineralization of metribuzin [4‐amino‐6‐(1,1‐dimethylethyl)‐3‐(methylthio)‐1,2,4‐triazin‐5(4H)‐one] were determined in the surface and subsurface horizons of a Dundee silty clay loam soil (Aeric Ochraqualf) from the Mississippi Delta. Residual metribuzin and metabolites were measured by HPLC or TLC methods during or after 91‐d incubations of treated soil in the laboratory. Metribuzin degradation was faster in the surface soil than in the subsurface soils. Degradation in the surface and the subsurface horizons were not described by first‐order kinetics. Degradation was a second‐order process in the surface soil, but only a half‐order process in the subsurface horizons. Considerably more mineralization of 14C‐metribuzin occurred in the surface (0‐ to 10‐cm depth) soil, with 15 to 20% evolved as 14CO2 after 91 d, vs. 5% from the subsurface soils. Substantial amounts of 14C‐bound residues were formed in both surface and subsurface horizons. Reduced microbial populations and activity corresponded to the reduced degradation of metribuzin in the subsoils.
A Comparison of Sorption Equilibrium Distribution Coefficients Using Batch and Centrifugation Methods
Authors: Celorie J. A. , Woods S. L. , Vinson T. S. , Istok J. D.
Published: July 2010

Sorption equilibrium distribution coefficients, Kd's, are often used in solute transport models to predict the movement of hazardous wastes in soils. Kd values can be determined in the laboratory by performing batch equilibrium tests or column studies. However, these tests suffer from disadvantages. Batch tests may overestimate sorption in natural soils due to the solids effect, and column studies conducted with fine‐grained soils require a long time to conduct. Centrifugation testing can alleviate these disadvantages by testing a soil column instead of a soil suspension, by imposing a confining stress on the soil, and by producing a greater pore water velocity. Centrifuge experiments were conducted on a kaolinite/phenol system using a constant head permeameter and a laboratory centrifuge. Kd values were estimated by modeling the generated breakthrough curves with a solute transport model. Kd values obtained in the centrifuge experiments were compared with Kd values measured in batch equilibrium tests. Although the Kd values determined in the centrifuge were slightly lower than the values predicted by extrapolating the batch data, the results were consistent with the solids effect.
Biological Monitoring of an Agricultural Food Chain: Soil Cadmium and Lead in Ruminant Tissues
Authors: Brams Eugene , Anthony William , Weatherspoon Lindsey
Published: July 2010

Low‐level contamination of a sandy soil with toxicants Cd and Pb at 0.01 to 9.0 and 3.0 to 54.0 mg kg−1 soil induced a significant toxicant accumulation in sudan‐sorghum hay [Sorghum sudanense (Piper) Stapf‐S. bicolor (L.) Moench] (0.5–5.0 and 0.2–1.5 mg kg−1 dry biomass), respectively. Ingestion of 22 to 222 mg Cd kg−1 body wt. by pregnant dairy goats (Capra hircus) from the consumption of hay over 98 d resulted in a significant, but relatively diminutive accumulation of Cd in the doe livers (0.01–0.02 mg kg−1) and brain cortex (0.002–0.007 mg kg−1) fresh wt., but not in doe kidneys and blood averaging 0.028 and 0.002 mg Cd kg−1 fresh tissues, respectively. Fetal blood and liver accumulated 2.0 and 4.0 mg Cd kg−1 fresh tissue, respectively, and fetal kidney exhibited a weak response (0.03–0.47 mg Cd kg−1 fresh tissue) to Cd ingested by the pregnant does. Consumption of 240 to 1230 µg Pb kg−1 body wt. induced 1.0 to 43.0 mg Pb kg−1 fresh tissue in the doe brain cerebellum, but not in the doe liver and blood averaging 0.09 and 0.017 mg Pb kg−1 fresh tissue, respectively. Fetal liver and blood averaged 0.043 and 0.014 mg Pb kg−1 tissue. Only minuscule amounts of soil Cd and Pb were retained in the select animal tissues via the ingestion of this hay. Only one‐ten‐millionth of labile soil Cd and Pb, respectively, accumulated in the select tissues of the pregnant does via the hay pathway. All these amounts were comparable to the norm. If these select animal tissues were used as food, no deleterious effect to human health should be induced.
Influence of Binary Interactions of Arsenate, Molybdate, and Selenate on Yield and Composition of Alfalfa
Authors: Khattak Riaz A. , Haghnia G. H. , Mikkelsen R. L. , Page A. L. , Bradford G. R.
Published: July 2010

Arsenic (As), selenium (Se), and molybdenum (Mo) are known to coexist in the soil solution as anions and thus may exert antagonistic or synergistic effects on their absorption by and translocation within plants. To evaluate the effects of binary interactions [As(V) × Se(VI), Se(VI) × Mo(VI) and As(V) × Mo(VI)] on growth and composition of alfalfa (Medicago sativa L.), three glasshouse sand culture experiments were conducted. Treatments applied in the half‐strength Hoagland's solution alone and in all possible factorial combinations for a given interaction consisted of 0, 0.25, 0.5, and 1.0 mg As(V) L−1 added as Na2HAsO4; 0 , 0.5, and 1.0 mg Se(VI) L−1 added as Na2SeO4; and 0.01, 1, 3, and 5 mg Mo(VI) L−1 added as Na2MoO4. Shoots were harvested three times and roots at the termination of the experiment. Plant tissues were dried, weighed, digested and analyzed for total As, Se, and Mo. Added Mo(VI) concentrations in the nutrient solutions had no significant effect on the tissue yield of alfalfa. Arsenic showed some adverse effect on shoot and root yields. The highest Se(VI) treatment decreased alfalfa shoot yield by 13.7 to 44.2% and root yield by 33% to 56.1%. The tissue As, Se, and Mo concentrations increased correspondingly with the increasing solution concentrations. At equal levels in the solution, alfalfa accumulated Se > Mo ≫ As. Increasing As(V) in solution caused significant increases in shoot Se concentrations and uptake, whereas solution Se(VI) showed a strong antagonistic effect on As uptake. The Se treatments significantly (P ~ 0.05) increased concentrations and uptake by shoot and root at all levels of solution Mo, except 0.01 mg L−1 where 1.0 mg Se L−1 increased Mo concentration, but had no significant effect on Mo uptake. Increasing Mo levels in the nutrient solution showed no significant effect on Se concentration and uptake by root. However, at 1.0 mg Se(VI) L−1, shoot Se concentration increased significantly at 3.0 and 5.0 mg Mo L−1. The solution As(V) showed no significant effect on tissue Mo at 0.01 and 1.0 mg Mo(VI) L−1 but increased Mo concentrations in shoots significantly (P ≤ 0.05) at 3.0 and 5.0 mg Mo(VI) L−1. These interactions may help to understand the complex interactions in soilplant systems. Based on the observed elevated tissue concentrations of As, Se, and Mo, these results might have important environmental implications for phytotoxicity to plants and foraging animals.
Vertical and Lateral Components of Soil Nutrient Flux in a Hillslope
Authors: Gaskin J. W. , Dowd J. F. , Nutter W. L. , Swank W. T.
Published: July 2010

The vertical and lateral components of chemical flux during storm events were investigated in a Typic Hapludult to assess their importance in understanding the effects of atmospheric deposition on hillslope sites. Vertical and lateral water flux were calculated from soil water potential data and hydraulic conductivity curves. Throughfall, stemflow, forest floor leachate, and soil solution from the BA, Bt, and BC horizons were sampled and analyzed for SO4, NO3‐N, Cl, HCO3, H, K, Ca, Mg, and Na. Total lateral flow as a ratio of total vertical flow averaged 0.23 and 0.30 in the A and BA horizons, respectively, indicating lateral fluxes were an important path of nutrient movement in the surface horizons. The highest lateral flow occurred in the A horizon during dry antecedent moisture conditions and in the BA horizon during wet antecedent moisture conditions. Fluxes of all ions except HCO3, NO3‐N, and H peaked in the forest floor leachate and the BA soil solution, then decreased with depth. Decreases of SO4 flux between the BA and BC horizons could not be explained by the lag of solute movement or by lateral solute losses, demonstrating the system was an effective SO4 sink.
Comparison of Tracer Mobilities under Laboratory and Field Conditions
Authors: Everts Christopher J. , Kanwar Rameshwar S. , Alexander E. Calvin , Alexander Scott C.
Published: July 2010

Transport of bromide, nitrate, lithium, and Rhodamine WT were compared in a repacked soil column and in a tile drained in a cropped field. Breakthrough of lithium and Rhodamine WT in a soil column was delayed by adsorption as compared to nitrate and bromide in the same column. When applied with irrigation water above a tile drain line, concentrations of all the tracers peaked in tile water 70 min after the start of an irrigation, then declined as irrigation continued. Tile flow responded to irrigation by increased flow and increased tracer concentration within 25 min after the start of an irrigation. Total percentage of tracers reaching tile flow from two tracer irrigations were 3.0, 2.5, 0.46, and 0.15%, respectively, of the nitrate, bromide, lithium, and Rhodamine WT applied with irrigation water. Of these losses, 67% of the cation‐exchanged lithium and 83% the adsorbed Rhodamine WT removed in tile flow during 56‐h of tile flow did so within 1 h after the irrigation ended. Proportion of nitrate and bromide losses in tile flow during the same time period were 40 and 35%, respectively.
Development and Testing of Open‐Top Chambers for Exposing Large, Perennial Plants to Air Pollutants
Authors: Mandl Richard H. , Laurence John A. , Kohut Robert J.
Published: July 2010

To study the effects of air pollutants on large perennial plants, two designs of large, open‐top chambers were tested in wind runnel studies and subsequent field trials. Flow visualization of air patterns in the wind tunnel showed that a frustum and inner baffle plate covering 50% of the top surface provided the best exclusion capabilities. This was quantified by measurement of pollutant distribution in scale models. Prototype chambers were erected around grape (Vitus sp.) vines in a commercial vineyard and evaluated over two growing seasons. Exclusion efficiencies of 80 to 95% were found during the test period. The rain shadow caused by the frustum was significant with losses greatest near the walls. The average increase in leaf temperature between ambient and within the chamber was 2.5 °C. Light intensity was reduced 14 and 22% in the circular and rectangular chamber, respectively. Although there is some modification of the plant environment, the chambers provide a suitable environment during the growing season for air pollution studies with large perennial plants.
Mechanism of Pyrite Oxidation in Aqueous Mixtures
Authors: Brown A. D. , Jurinak J. J.
Published: July 2010

The rate of pyrite oxidation in aqueous mixtures was studied at 25 °C for periods up to 3 wk. Dissolved plus citrate‐dithionite‐extractable Fe was used to measure the extent of reaction. Pyriteoxidation rate was independent of time (zero order) in the presence of NaClO4, CaCO3, and NaHCO3. Oxidation rate was a linear function of substrate concentration. Oxidation rates increased with pH. Solutions of Cl−, SO2−4, and diethylenetriamine pentaacetic acid (DTPA) inhibited pyrite oxidation. The data are consistent with a surface‐controlled reaction with Fe3+ as the rate‐controlling oxidant. The effect of OH−, Cl−, SO2−4, and DTPA on oxidation rates is explained by the relative reactivity of each of these in ligand exchange during an inner‐sphere electron transfer. It is suggested that OH− is the rate‐determining bridging ligand between Fe3+ and the pyrite surface. This reaction is compatible with recently proposed surface‐reaction mechanisms.
Chemical Effects of Saline Irrigation Water on a San Joaquin Valley Soil: I. Column Studies
Authors: Thellier Catherine , Sposito Garrison , Holtzclaw Kenneth M.
Published: July 2010

A glasshouse soil column experiment was performed to characterize salinity and sodicity developed from waters of differing composition applied to a representative soil from the San Joaquin Valley of California. The soil column experiment was designed to simulate physicochemical conditions in a field experiment conducted in the western San Joaquin Valley, where an Entisol above a shallow, saline aquifer was irrigated with waters of varying quality. Columns 0.46 m long containing the Entisol were leached with “California Aqueduct water” (EC = 0.72 dS m−1, SAR = 4 molc 1/2m−3/2) or with saline “well water” (EC = 8 ds m−1, SAR = 13 molc 1/2m−3/2) for periods up to 1 yr. When a simulated “aquifer” was 0.43 m below the soil surface, leaching with aqueduct water produced a positive downward gradient of soluble salt concentrations and exchangeable Na, whereas leaching with well water produced a dramatic increase of sodicity at the soil surface and a zone of soluble bivalent cation accumulation about 0.2 m below. These effects reflected the combined influence of the applied water quality and evaporative capillary rise from the saline “aquifer.” After the simulated “aquifer” was withdrawn, soil saturation extracts indicated equilibration with the applied waters after 0.5 to 1 yr, the rate being greater under leaching with aqueduct water. The saturation extract and drainage effluent for the soil receiving aqueduct water became more dilute, producing calcite dissolution and increasing exchangeable Ca, with a consequent decline in sodicity. The soil receiving well water showed an increase in exchangeable Na at the expense of exchangeable Ca, with little or no change in exchangeable K and Mg. At the completion of the experiment, the soil irrigated with well water had become more saline and sodic but, since EC was sufficiently high as compared to SAR, no major permeability problems with the soil were expected. Therefore, from the results of this study, the reuse of saline drainage water would appear to be suitable for agricultural purposes provided that salt‐tolerant crops were grown.
Chemical Effects of Saline Irrigation Water on a San Joaquin Valley Soil: II. Field Soil Samples
Authors: Thellier Catherine , Holtzclaw Kenneth M. , Rhoades J. D. , Sposito Garrison
Published: July 2010

Representative samples were collected from the surface horizon of an Entisol in field plots that had received applied waters of differing quality over a 5‐yr period while cropped with cotton (Gossypium sp.), wheat (Triticum sp.), and sugarbeets (Beta vulgaris L.). Irrigation was either with California Aqueduct water, saline well water, or a 1:1 mixture of the two. The soil samples were analyzed for saturation extract electrolytic conductivity (ECe); soluble and exchangeable cations; and carbonate and gypsum content. Both salinity and sodicity increased in the soil samples with decreasing applied water quality, and all of the samples were more saline and sodic and contained more calcite than at the initiation of the field experiment. The samples from plots receiving well water had developed values of ECe and sodium adsorption ratio (SARe), as well as an exchangeable sodium percentage‐SARe relationship, identical to those observed after 1 yr in a companion soil column experiment. The samples from plots receiving aqueduct water were more saline and sodic than in the corresponding soil column experiment, however, probably because of less effective leaching in the field experiment. These results confirmed the hypothesis that the chemical properties of the field soils would be determined by the interplay between the applied water and evaporative capillary rise from the shallow aquifer. Since the increased salinity of the soil samples compensated for their increased sodicity, no permeability problems were expected, and irrigation with saline water should be successful for salt‐tolerant crops if leaching were adequate.
Control of Arborescent Vegetation below Power Lines with Wastewater Sludge
Authors: Grenier Yvon , Couillard Denis
Published: July 2010

A 1‐yr field study was conducted to determine whether fertilization with wastewater sludge could favor growth of herbaceous and shrub species to inhibit or eliminate the growth of tree species under power lines. Results show that a significant proportion of the trees died: mortality ranged from 35 to 100% on plots that received 160 Mg ha−1 of sludge, and ranged from 0 to 31% on control plots. The surviving trees showed accelerated growth. Means of height increments ranged from 17 to 86 cm on plots receiving 80 Mg ha−1 of sludge, and ranged from 5 to 31 cm on control plots. Sludge applications also decreased regeneration success of trees in the current year, with a minimum of 0.8 and a maximum of 7.0 new seedlings per 12.5 m2 on treated plots, as compared to 14.0 new seedlings on control plots. With the short duration of this preliminary study, it is concluded that the herb and shrub strata did not have sufficient time to fully develop in a single growing season and that the hypothesis remains to be verified.
Growth and Elemental Content of Slash Pine 16 Years after Treatment with Garbage Composted with Sewage Sludge
Authors: Jokela E. J. , Smith W. H. , Colbert S. R.
Published: July 2010

Landspreading of organic wastes remains an environmentally acceptable option for recycling nutrients. This study assessed tree growth and elemental tissue concentrations in a slash pine (Pinus elliottii Engelm.) plantation treated 16 yr previously with four rates (0, 112, 224, 448 Mg ha−1) of municipal garbage composted with sewage sludge. Tree growth was significantly greater where garbage compost was applied. Stem wood biomass increased from 55.7 to 94.7 Mg ha−1, a 1.7‐fold increase over the control for the heaviest garbage application rate. Annual tree basal area increment responses were also largest and most long‐lasting (up to 9 yr) for the 448 Mg ha−1 rate. Significant but modest treatment associated increases in concentrations of N, P, B, Fe, Al, and Zn in pine tissues (foliage, stem wood), and P and Ca in Rubus spp., a dominant understory plant, were found after 16 yr. Analysis of pine xylem tissues corresponding to the juvenile and post‐crown closure growth phases revealed significantly higher concentrations of K, Ca, Mg, Cu, Al, and Zn in the latter period. Results suggest that landspreading and recycling degradable organic wastes in forests can increase tree and understory growth without long‐term deleterious ecosystem effects. The applicability of these results to a typical community in a forested landscape is illustrated.
Leaf Gas Exchange of Maize Plants Fumigated with Sulfur Dioxide
Authors: Gerini O. , Guidi L. , Lorenzini G. , Soldatini G. F.
Published: July 2010

Leaf gas exchange was measured in maize (Zea mays L.) plants that had been exposed continuously for a period of 4 wk to a range of SO2 concentrations applied in fumigation chambers. Exposure to a constant SO2 level of 43 and 71 nLL−1 induced a decrease in the apparent photosynthesis and quantum yield, and an increase in the stomatal conductance and transpiration rate in comparison to the charcoal‐air filtered controls. This would suggest that the reduction in photosynthesis observed was mainly due to nonstomatal components, i.e., the direct effect of SO2 on the mesophyll.
Geochemical Factors Controlling the Mobilization of Inorganic Constituents from Fossil Fuel Combustion Residues: I. Review of the Major Elements
Authors: Mattigod S. V. , Rai Dhanpat , Eary L. E. , Ainsworth C. C.
Published: July 2010

Large quantities of fossil fuel combustion (FFC) wastes, such as fly ash, bottom ash, flue gas desulfurization (FGD) sludge, and oil ash are being disposed of on land. There is a need to accurately assess the mobilization of elements that results from the weathering of these wastes. To help meet this need, available data on physical, chemical, mineralogical, extract, and leachate characteristics have been compiled and reviewed, and a comprehensive approach to understanding how major elements are mobilized from fossil fuel wastes is described. Many of the physical properties of fly ashes overlap those of bottom ashes; similar data for FGD sludge and oil ashes are sparse. One taxonomic and three utilitarian classification schemes have been proposed for fly ashes. However, no taxonomic system is applicable to all FFC wastes. The ranges of concentrations of Al, Ca, and Fe found in these wastes were within the ranges of their concentrations in soils. Concentrations of K, Na, Mg, and S in some FFC wastes may exceed their highest concentrations in soils. The matrix of fly ashes consists principally of quartz, glass, and mullite. As minor components in fly ashes, anhydrite, lime, periclase, hematite, and magnetite are reported frequently. A minor fraction of many of the major elements may also be present in a glassy phase. The principal compounds in FGD sludges are sulfites, sulfates, carbonates, and hydroxides of Ca. The oil ashes contain mainly sulfates and oxides of Al, Na, Fe, and Mg. Water extracts of FFC wastes contain significant fractions of Ca, Mg, K, and Na, a fact that confirms the presence of these elements in highly soluble forms. Leaching studies conducted using fly ash columns have shown that initial leachates contain high concentrations of Ca, Na, K, and S and that as leaching continues these concentrations decline and reach steady states. Usually only negligible fractions of Si, Al, Fe, and Mg are leached from fly ash columns. In this article, a comprehensive approach is suggested, one that combines thermochemical principles with chemical and mineralogical data to predict the upper limits of elemental concentrations that can be attained in leachates from weathering FFC wastes. This thermochemical approach has shown that secondary solid phases may control concentrations of Al, Ca, and S measured in extracts of fly ashes and FGD sludges and in pore waters from fly ash lysimeters at a field site. Characterization of weathered wastes and improved thermochemical data for secondary solid phases in these wastes will be useful for understanding and predicting the chemistry of leachates.
Tracked Vehicle Impacts on Vegetation at the Pinon Canyon Maneuver Site, Colorado
Authors: Shaw R. B. , Diersing V. E.
Published: July 2010

The effects of military tracked vehicle maneuvers on the vegetation of the Pinon Canyon Maneuver Site (PCMS), southeastern Colorado, were assessed from 1985 to 1987. Tracking decreased plant basal and litter cover and increased bare ground. The immediate effect of tracking was to reduce perennial warm‐season grasses [primarily blue grama, Bouteloua gracilis (H.B.K.) Lag. ex. Griffith] followed by the invasion of annual cool‐season grasses [sixweeks grass, Vulpia octoflora (Walt.) Rybd., and little barley, Hordeum pusillum Nutt.] and annual warm‐season forbs [sunflower, Helianthus annuus L., russian thistle, Salsola iberica Sennen & Pau, and kochia, Kochia scoparia (L.) Schrab.]. In untracked areas, herbaceous plant composition did not change; however, litter increased and bare ground and basal cover decreased. Changes in cover in untracked areas was attributed to above average precipitation and the cessation of domestic livestock grazing. Overall (tracked plus untracked areas), total cover increased on PCMS, but the proportion of annual cover also increased. Woody plant density decreased an average of 9% from 1985 to 1987. Long‐term management of the soil and vegetative resources of PCMS are discussed.
Biodegradation of a Gas Oil Applied to Aggregates of Different Sizes
Authors: Mott Stella C. , Groenevelt Pieter H. , Voroney R. Paul
Published: July 2010

Land treatment of oily wastes involves repeated application and tillage cycles to promote biodegradation of the waste. Tillage intensifies greater than current practices would result in smaller aggregates, promote oil‐soil interaction, and likely improve waste biodegradation. Due to the cyclical nature of treatment, it was unclear whether the obvious effect of oil‐soil mixing after application or the more subtle effect of soil surface preparation before the next application would be the primary effect of increased tillage intensity. Previously untreated soil was sieved into aggregates of the following size ranges: coarse (19–25 mm in diam.), medium (5–10 mm), and fine (1–2 mm). Oily waste, emulsified in sufficient water to bring the soil to 25% water content, was evenly applied to the surface of aggregates from each size range. Treated and untreated samples were incubated for 14 d at 25°C. Biodegradation was measured by CO2 entrapment in KOH. After 14 d, the coarse and medium aggregates were ground to approximately 2 mm. Incubation of all samples was resumed without further waste application. A one‐component exponential model regression indicates that application to fine aggregates resulted in a larger available mineralizable carbon pool, with more CO2 produced from treated fine aggregates. The effects are attributed to the larger available surface area. Although grinding caused a CO2 flush lasting several days, the pregrinding pattern was soon reestablished. The laboratory results suggest that waste biodegradation is inversely proportional to aggregate size before application, and that soil surface preparation into fine aggregates may be more beneficial than tillage after application.
Lead Mobility within the Xylem of Red Spruce Seedlings: Implications for the Development of Pollution Histories
Authors: Donnelly John R. , Shane John B. , Schaberg Paul G.
Published: July 2010

Development of Pb pollution histories using tree ring analyses has been troubled by possible mobility of Pb within stem xylem. In a 2‐yr study, we exposed red spruce (Picea rubens Sarg.) seedlings to Pb during one growing season, with Pb excluded in either the previous or following growing season. Lead levels within xylem rings and bark were subsequently determined using atomic absorption analyses. Lead concentrations in tissues from exposed seedlings were significantly higher than controls, and significant Pb concentrations were found in xylem formed during periods of Pb exclusion. Routes of Pb movement are uncertain, but were most likely acropetal from temporary storage sites in the roots.
Sewage Sludge Effects on Soil and Plant Quality in a Degraded, Semiarid Grassland
Authors: Fresquez P. R. , Francis R. E. , Dennis G. L.
Published: July 2010

A major problem affecting grassland productivity in the semiarid southwestern USA is the low quantity of soil organic matter and plant‐available N. In this study, dried, anaerobically digested sewage sludge was applied at three rates (22.5, 45, and 90 Mg ha−1) to a degraded semiarid grassland site to determine the effects of sludge on soil chemical and heavy metal properties, and vegetative yields and quality over two growing seasons. Most nutrients, including soil N, P, and K, increased linearly as a result of sludge amendment. Soil pH decreased linearly from 7.8 to 7.4 with the application of sludge after the second growing season, but did not significantly increase the solubility of soil heavy metals (Pb and Cd). On the other hand, the levels of DTPA‐extractable soil micronutrients (i.e., Cu, Mn, Zn) increased linearly with sludge rates to levels recommended for adequate plant growth. Total herbaceous plant yields increased significantly with sludge amendment, particularly at the 45 Mg ha−1 sludge rate, as compared with the control treatment. Blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Steud.] yields increased two‐ to threefold in amended plots over the unamended control after two growing seasons. The forage quality of blue grama, galleta [Hilaria jamesii (Torr.) Benth.], and bottlebrush squirreltail [Sitanion hystrix (Nutt.) J.G. Sm.], improved significantly as the levels of tissue N, P, and K, and crude protein increased linearly with sludge application. As expected, levels of Cd and Pb in all plant tissues did not increased significantly as a result of sludge amendment. All micronutrients increased to acceptable levels in deficient plant tissues. Sewage sludge applied at the rate of 45 Mg ha−1 gave the most favorable soil and vegetation results.
Thallium Toxicity in Bean
Authors: Kaplan D. I. , Adriano D. C. , Sajwan K. S.
Published: July 2010

Hydroponic, rhizotron, and field studies were conducted to determine the effect of Tl on the biomass and nutrient concentrations in roots and leaves of bean plants. Loamy sand soils in the field and rhizotron cells were treated with Tl, Cd, Cr, Ni, and V. Bush beans (Phaseolus vulgaris L.) were planted in both studies. The hydroponic study consisted of growing soybean [Glycine max (L.) Merr.] in Hoagland's solution treated with Tl. All three studies showed that Tl accumulated in the roots and not in aerial portions of the plant. In the hydroponic study, micromolar concentrations of Tl added to the nutrient solution drastically altered the concentration of certain nutrients in soybean tissues and significantly reduced plant biomass. Thallium‐treated plants had fewer nodes than the normal ones. In addition, Tl caused the roots to become severely stunted with few lateral branches. The lower, more mature leaves of the treated plants exhibited chlorosis in spite of Fe concentrations comparable to the control plants. Based on tissue analyses, there was a concomitant increase in K concentrations in high Tl treatments, whereas Ca and Mg concentrations in leaves decreased below critical levels for normal growth. In addition, diagnosis and recommendation integrated system (DRIS) indicated that Ca was relatively more deficient than Mg; DRIS also identified Mn as being deficient.
Aqueous Behavior of Chromium in Coal Fly Ash
Authors: Rai Dhanpat , Szelmeczka Roger W.
Published: July 2010

Studies were conducted to determine the dominant reactions controlling aqueous Cr concentrations in four coal fly ashes. The fly ashes were adjusted to a range of pH values between 2 and 10. Chromium was found to be present in these aqueous and solid phases as Cr(III). Because of the amorphous character of the important Cr(III) compounds [(Fe,Cr)(OH)3 and Cr(OH)3] and because of the very low total Cr content (<0.025%) of the fly ashes, it was not possible to identify directly the Cr‐containing compounds. However, an indirect technique for identifying Cr compounds, comparison of observed activities with those in equilibrium with known solid phases, and with those obtained after spiking the coal ash suspensions with Cr(III), suggest that Cr concentrations are controlled by (Fe,Cr)(OH)3(am) at low pH and by (Fe,Cr)(OH)3(am) and/or Cr(OH)3(am) at pH values greater than ∼5.
Virus Transport and Survival in Saturated and Unsaturated Flow through Soil Columns
Authors: Powelson David K. , Simpson James R. , Gerba Charles P.
Published: July 2010

Water with entrained disease‐causing virus entering soil normally passes through water‐saturated and unsaturated regions before reaching the groundwater. The effects of saturated and unsaturated flow on the survival and transport of a virus, MS‐2 bacteriophage, were compared. The viruses were added to well water and applied to soil columns 0.052 m in diameter and 1.05 m long. The soil material was Vint loamy fine sand (a sandy, mixed, hyperthermic Typic Torrifluvent) mixed with recent alluvium. Samples of the soil water were taken daily at 0.20, 0.40, and 0.80 m depths through porous stainless steel samplers and at 1.05 m from the percolate leaving the column. For saturated flow the virus concentrations reached the influent concentration in less than two pore volumes (PV). For unsaturated flow the concentrations remained at levels much lower than the influent, ranging from 27% of inflow at 0.20 m (18 PV) to 5% at 1.05 m (3.3 PV). At the end of the experiments soil samples from each depth were assayed to determine virus adsorption to the soil. The average distribution coefficient of the unsaturated columns, 0.27, indicates very little adsorption. The number balance showed that only 39% of the unsaturated flow virus were accounted for. It appears that under unsaturated flow conditions enhanced inactivation of this virus occurs.
Effect of Conventional vs. No‐Tillage on Pesticide Leaching to Shallow Groundwater
Authors: Isensee A. R. , Nash R. G. , Helling C. S.
Published: July 2010

A field site was established at Beltsville, MD, in 1986 to assess the effect of conventional and no‐till cultural practices on the movement of pesticides into shallow groundwater. Groundwater samples taken from unconfined (<1.5 m deep) and confined (<3 m deep) monitoring wells in 1986–1988 were analyzed for atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine], deethylatrazine [6‐chloro‐N‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine], alachlor [2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxymethyl)acetamide], cyanazine [2‐[[4‐chloro‐6‐(ethylamino)‐1,3,5‐triazine‐2‐y1]amino)‐2‐methylpropanenitrile], and carbofuran (2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranyl methylcarbamate). Atrazine was found in groundwater all year, while cyanazine, alachlor, and carbofuran were present only for a short period (<3 mo) after pesticide application. Fairly constant background levels of <0.5 µg L−1 atrazine were found under fields treated before 1986, while levels under continuously treated fields were <2.0 µg L−1 for 22 of 25 samplings. Pesticide residues in unconfined groundwater were usually higher (ca. 2 to 4×) than in confined groundwater. Rainfall timing relative to pesticide application was critically important to pesticide leaching. A prolonged rain immediately after the 1988 application resulted in peak atrazine and cyanazine levels of ca. 200 µg L−1 in unconfined and ca. 30 to 40 µg L−1 in confined groundwater, which resulted in short‐term levels ca. 2 to 50× greater under no‐till than conventional till plots. Results of this study suggest that preferential transport occurred.
Nitrate Contamination of Groundwater under Irrigated Coastal Plain Soils
Authors: Weil R. R. , Weismiller R. A. , Turner R. S.
Published: July 2010

To develop best management practices (BMP) for agricultural land to protect groundwater, data is needed on the leaching of N from irrigated coastal plain soils treated with poultry manure. This study was conducted to determine the vertical and seasonal patterns of NO3 leaching under such soils. Four commercially farmed corn (Zea mays L.) fields were studied, two receiving only fertilizer N (240 to 360 kg N ha−1 over a 2‐yr period) and two with a continuing history of poultry manure applications (25–29 Mg ha−1 over 2 yr). In each field, a transect of four monitoring wells was installed 4 to 8 m deep (1 m below the seasonally low water table). Three additional wells were installed in forestiand adjacent to three of the fields. Groundwater and soils (to 1.5‐m depth) were periodically sampled for analysis of NO3‐N. Under the unmanured field, groundwater NO3‐N concentrations averaged 15.1 mg L−1 during August through November 1986, while the corresponding figure for the manured fields was not significantly different at 18.3 mg L−1. Two months after spreading manure in November and December, as much as 104 mg NO3‐N was measured in the groundwater under the manured fields. From December 1986 through September 1987 the groundwater under the manured fields had significantly higher NO3‐N concentrations than did that under the unmanured fields (43.7 vs. 18.1 mg L−1, respectively). Only for one well site with a buried A horizon did high Cl to NO3‐N ratios and low NO3‐N concentrations indicate rapid denitrification. The forestland groundwater always contained <1 mg NO3‐N L−1, and high Cl to NO3‐N ratios, suggesting that NO3 in the cropland groundwater was lost after entering the forested areas, and that forests may therefore protect waterways from subsurface N contamination.
Assessment of Cumulative Impacts to Water Quality in a Forested Wetland Landscape
Authors: Childers Daniel L. , Gosselink James G.
Published: July 2010

One important focus of applied ecology is the assessment of environmental impacts and the recommendation of ways to avoid or minimize these impacts. Cumulative impacts result from the accumulation of many human activities whose impacts, although not individually measurable, together sum to significant adverse effects. Assessment of cumulative impacts requires a landscape approach and large‐scale analysis. In our procedure for determining cumulative impacts in bottomland hardwood forests (BLHF), changes in landscape integrity over time were assessed using structural and functional ecosystem indices. In this article we present a historical analysis of water quality in the Tensas Basin, Louisiana, as part of the cumulative impacts analysis of this BLHF landscape. Historical records of suspended sediment, N, P, and turbidity from three streams in the Tensas Basin were analyzed. Significant positive relationships between water levels in these streams and concentrations of total P, total Kjeldahl N, total suspended sediment, and turbidity confirmed a loading phenomenon characteristic of watersheds in which much of the original forest cover has been cleared. Eighty‐five percent of the original forest in the Tensas Basin has been converted to agricultural fields. Temporal trends in nutrient concentration show that water quality has been declining steadily since 1958 in one river, whereas in the other two the decline largely occurred before then. Nitrogen/phosphorus ratios in two of the three rivers (2.9:1 and 4.6:1 by weight, 6.4:1 and 10.2:1 by molar ratio) were lower than expected in P‐limited freshwater systems, where N/P ratios are generally > 10 to 15 by molar ratio. Most of the excess in P is probably related to the geochemical adsorption of P to sediment particles and selective loading of P during erosive storm events. As a result, in much of the Tensas Basin the nutrient limiting aquatic primary productivity—and thus the most critical nutrient to control—may be N. Between 1978 and 1986, P levels exceeded 0.1 mg L−1 96% of the time (P concentrations > 0.1 mg L−1 signal eutrophy in lotic systems). Total suspended sediment concentration patterns were erratic and in excess of 80 mg L−1 over half the time in two of the three streams studied (1966–1986). A goal‐oriented management plan for improved water quality in the Tensas Basin was devised based on this cumulative impact assessment. Improvement of the aquatic ecosystem can be achieved in a number of ways, including the reestablishment of natural hydrologic flow wherever possible, the use of agricultural practices that reduce runoff, the protection of existing forested corridors along streams, and the mitigative creation of new buffering zones. In this conservation plan, site‐by‐site permitting occurs within the context of a comprehensive plan for managing the renewable resources of the entire Tensas Basin landscape; a plan based on the intensity of past cumulative impacts to the ecosystem.