bluuebunny/crossref_metadata_2025 huggingface dataset:
Field Duration of Chlorsulfuron Bioactivity in the Central Great Plains
Authors: Anderson R. L. , Humburg N. E.
Published: July 2010

The duration of chlorsulfuron {2‐chloro‐N [(4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐yl)aminocarbonyl]benzenesulfonamide} bioactivity in Central Great Plains soils was determined by measuring the influence of several environmental factors on chlorsulfuron degradation. Chlorsulfuron was applied at 35 and 70 g ha−1 to four soils: Platner sandy loam and Weld (Aridic Paleustolls) loam at Akron, CO; Roxbury (Cumulic Haplustoll) silt loam at Jetmore, KS; and Rosebud (Aridic Argiustolls) sandy loam at Chugwater, WY. Soil pH, organic matter level, number of precipitation events >0.25 cm, and leaching were the major environmental factors influencing chlorsulfuron duration of bioactivity. A chlorsulfuron rate × soil × year interaction occurred, but this interaction was not consistent over all soils. A model developed for predicting chlorsulfuron duration of bioactivity would be more accurate if designed for soils with similar organic matter levels, as organic matter level influenced duration of bioactivity and leaching of chlorsulfuron. Chlorsulfuron leaching was also affected by soil type and year of study. In greenhouse bioassay studies, sunflower (Helianthus annuus L.) did not differ from corn (Zea mays L.) in sensitivity to chlorsulfuron residues in soil.
Removal of Two Chlorinated Compounds from Secondary Domestic Effluent by a Thin Film Technique
Authors: Dierberg Forrest E. , Goulet Normand A. , DeBusk Thomas A.
Published: July 2010

Removal of two chlorinated compounds from secondary domestic wastewater was examined in central Florida using four thin‐film raceways (7.32 m long by 1.22 m wide by 4.0 cm deep) containing the aquatic macrophyte pennywort (Hydrocotyle umbellata L). Two raceways received secondary effluent amended with 5.0 mg/L of monochloramine plus 1.0 mg/L of 2,4‐dichlorophenol (2,4‐DCP) and two raceways received secondary effluent only (controls). Mass balances indicated 100% removal of monochloramine and >95% removal for 2,4‐DCP after loadings of 25.2 and 6.1 g/m2, respectively, over the 60‐d study. This study demonstrates the potential of aquatic macrophyte‐based thin film systems for reducing concentrations of chlorinated compounds to acceptable levels under high wastewater loadings and short residence times (∼ 10 h).
Acidic Deposition and Tree Growth: I. The Use of Stem Analysis to Study Historical Growth Patterns
Authors: LeBlanc David C. , Raynal Dudley J. , White Edwin H.
Published: July 2010

Radial growth of three coniferous tree species, representing an assumed spectrum of susceptibility to acidic deposition effects on cation leaching, was analyzed by detailed stem analysis to determine if a decline in growth, unrelated to natural determinants of growth, has occurred since the 1950s. Various measures of tree growth derived from detailed stem analysis are shown to be very useful in assessing tree growth responses to environmental factors. Correlations between breast height and whole‐stem analysis data were highly variable and generally poor for two of three species studied. Species/site groups identified as potentially more susceptible to acidic deposition effects exhibited synchronous decreases in growth after 1960, but the initiation of decreased growth was coincident with documented climatic anomalies (drought and winter temperatures) and cannot be directly attributed to acidic deposition effects. Quantitative dendroclimatological analyses are necessary to assess the relationship between these episodes of decreased growth and climatic variables before the role of potential acidic deposition‐mediated effects can be evaluated. The role of acidic deposition in the observed growth declines cannot be discounted based on our analyses. However, tenable alternative hypotheses involving the action of natural determinants of growth (climate and maturation) are presented.
Acidic Deposition and Tree Growth: II. Assessing the Role of Climate in Recent Growth Declines
Authors: LeBlanc David C. , Raynal Dudley J. , White Edwin H.
Published: July 2010

Detailed stem analysis was used to measure historical growth of three coniferous tree species assumed to represent a wide range of susceptibility to potential acidic deposition effects on cation leaching. Sample trees were growing on an outwash plain in even‐aged monoculture plantations with similar stand histories and soils. Stepwise multiple regression was used to assess relationships between observed variations in growth and climatic variables. The ring‐number sequence, a relative measure of historical tree growth that did not require standardization, was particularly useful in analyses of growth‐environment relationships for young trees that exhibit consistent apical growth. Species/site groups assumed to be more susceptible to acidic deposition effects exhibited significant decreases in growth after 1960, but these decreases were correlated with climatic variables. Growth‐climate relationships derived for the pre‐1960s period did not predict decreases in tree growth observed during the mid‐1960s and late‐1970s, indicating a lack of time stability in growth‐climate relationships. This may be due to many factors, including maturation, climatic anamolies, and/or acidic deposition effects. This correlational study can not establish cause‐and‐effect relationships between tree growth and climate or acidic deposition. Independent confirmation and studies of the physiological mechanisms involved are needed to substantiate these results.
Effect of Municipal Solid Waste Leachate Composition on Zinc Migration through Soils
Authors: Boyle M. , Fuller W. H.
Published: July 2010

The relative impact of adjusting two main constituents of municipal solid waste (MSW) leachate, total organic carbon (TOC), and total soluble salts (TSS) on Zn migration through soils was evaluated. Four Zn‐enriched leachates of different TOC and TSS composition were perfused through five soils. The effluents from the 20 soil columns were collected and analyzed for the presence of Zn. Solution displacement continued until the concentration of the Zn in the effluent equaled that of the influent (100 mg L−1). In general, higher TOC and TSS levels in the leachate facilitated the migration of Zn through soil. The soil properties associated with Zn retention were, in order of importance, surface area, cation exchange capacity (CEC), and percent clay content. The TOC and TSS content of the MSW leachate studied were found to be more important in determining Zn attenuation behavior than soil characteristic.
Plant Exposure Chambers for Study of Toxic Chemical‐Plant Interactions
Authors: McFarlane J. Craig , Pfleeger Thomas
Published: July 2010

Chambers for the study of plant uptake and phytotoxicity of toxic, radio‐labeled chemicals are described. The chambers are designed to meet the criteria of continuously stirred tank reactors while providing containment for toxic chemical. They are computer managed and operated within a controlled environment room. Besides providing controlled conditions within the contained spaces, continuous measurements are made of various environmental parameters and plant transpiration, net photosynthesis, and dark respiration in up to 18 separate chambers.
Plant Availability and Uptake of Molybdenum as Influenced by Soil Type and Competing Ions
Authors: Smith C. , Brown K. W. , Deuel L. E.
Published: July 2010

Irrigation has been proposed as a possible disposal method for large quantities of water having high concentrations of Mo (5–100 mg L−1) resulting from mining and reclamation activities. To assess this possibility, laboratory and greenhouse experiments were conducted to evaluate the influence of competing ions in the soil solution on the relationship between the sorption of Mo by soils and Mo uptake by grass. Laboratory experiments assessed Mo sorption by Edroy clay (Vertic Haplaquoll), Olmos loamy sand (Petrocalcic Calciustoll), and Randado sandy loam (Ustollic Paleargid). Soil treatments included 1, 5, 10, 20, 50, and 100 mg Mo L−1 added as ammonium molybdate in solutions of 0, 167, 333, and 500 mg L−1 concentrations of Cl− and 0, 226, 451, and 677 mg L−1 concentrations of SO2−4 salts. Sorption data fit the Freundlich isotherm. The Olmos soil had the highest CaCO3 content and sorbed the most Mo. The Edroy soil had the lowest pH and sorbed the least Mo. The presence of Cl− in solution increased Mo sorption, while SO2−4 reduced Mo sorption in all three soils. In the greenhouse study, soils were treated with 0, 6.5, 13.0, and 26.0 mg Mo kg−1 soil; 167, 334, and 501 mg Cl kg−1 soil; and cropped with bermudagrass, Cynodon dactylon (L.) Pers. No toxic symptoms or yield decreases were noted as a result of Mo or salt additions. Plants grown in soil containing 26.0 mg Mo kg−1 accumulated up to 600 mg Mo kg−1 dry matter and would be toxic to ruminants. The Mo concentrations in grass grown on the three soils were ranked from highest to lowest as Edroy > Randado > Olmos. Chloride addition to the soil had no significant (P <0.05) effect on bermudagrass Mo content. Both the concentration of Mo in the vegetation and the amount of Mo taken up by the vegetative cover were well correlated (r2 = 0.73 and 0.83, respectively) with the equilibrium solution Mo in the soil as calculated from the sorption isotherms. Thus, the results indicate that there is a strong relationship between the laboratory sorption data and the equilibrium solution Mo in the soil and that grass grown on soil irrigated with waters high in Mo may reach levels that are expected to be toxic to animals.
Evaluation of Pesticide Groundwater Pollution Potential from Standard Indices of Soil‐Chemical Adsorption and Biodegradation
Authors: Jury William A. , Focht Dennis D. , Farmer Walter J.
Published: July 2010

A mathematical screening model of the pesticide leaching process is used to estimate the potential for a pesticide to reach groundwater at significant concentrations. The model assumes steady water flow, equilibrium linear adsorption, and depth‐dependent first‐order biodegradation and predicts groundwater travel times and residual concentrations that depend on soil and environmental conditions as well as pesticide adsorption and decay constants. When groundwater protection is expressed as a condition that the residual undegraded pesticide mass remaining below the surface layer of soil must be less than a specified fraction of the initial mass added in a pulse application at the surface, the model prediction is shown to reduce to a linear inequality between the organic C partition coefficient Koc and the biochemical half‐life, τ. The screening model is illustrated on 50 pesticides and two scenarios representing low and high potential for groundwater contamination. The calculations reveal a significant dependence on site‐specific soil and environmental conditions, suggesting that regulations restricting pesticide use should take soil and management factors as well as chemical properties into account when screening for groundwater pollution potential.
Pesticide Contamination of Groundwaters in the Mahantango Creek Watershed
Authors: Pionke H. B. , Glotfelty D. E. , Lucas A. D. , Urban J. B.
Published: July 2010

Waters from 20 wells in a primarily agricultural Pennsylvania watershed were analyzed for the most heavily and extensively applied pesticides as determined by farm survey. Those analyzed were atrazine, metolachlor, cyanazine, alachlor, terbufos, chlorpyrifos, fonofos, and carbofuran. No metolachlor, alachlor, terbufos, chlorpyrifos, fonofos, or carbofuran were detected. However, atrazine concentrations ranging from 13 to 1110 ng/L were found in 14 of the 20 wells. These findings suggest widespread atrazine contamination of the groundwaters, but at extremely low concentrations. Cyanazine was found above trace concentrations in one well. Although there was only one record of application, simazine was found in seven wells within the range of 10 to 170 ng/L. The degree and spatial distribution of atrazine contamination depended mostly on the frequency and distribution of corn production. The highest atrazine concentrations were associated mostly with continuous corn production. Aquifer rock type, depth to water table, and the degree of recharge short‐circuiting estimated from PO4 contamination of groundwater, were concluded not to be important factors. Generally, Cl provided a better index of atrazine contamination than did NO3 because extensive denitrification occurred in several wells. The probability of atrazine being found above the minimum detection limit was high when Cl exceeded 3 mg/L or NO3‐N exceeded 4 mg/L.
Biogeochemical Control on Metal Distribution and Accumulation in Louisiana Sediments
Authors: Feijtel T. C. , DeLaune R. D. , Patrick W. H.
Published: July 2010

Metal accumulation rates were determined from sedimentation rates and the distribution of 137Cs and total metal content in cores collected from freshwater, brackish, and saltwater bay bottoms in Barataria Basin, LA. Vertical accretion rates ranged from 0.65 cm/yr in the northern freshwater part of the basin up to 1.1 cm/yr in the lower saline estuary. Metal sedimentation and accumulation rate estimates along this salinity gradient indicated that metals were concentrated by a factor of two to four in the saline end‐member. Manganese, however, exhibited an estimated depletion of 1.95 g/(m2 yr) in the lower part of the basin, due to its postdepositional mobility. A principal component and regression analysis of total metal distribution showed that the metal content could be predicted by the C content of the substrate (R = 0.89**; significant at the 0.01 probability level). This suggested the sedimentation of metal‐rich organic matter, most likely originating from adjacent marshes. Clay and silt content were insignificant as predictor variables. In the subsurface layer (0–4 cm), 18% of the variability in Fe and 27% in the variability in Mn content were attributed to redox processes, and were adequately predicted by the redox potential of the sediment (R = 0.60*; significant at the 0.05 probability level). Partial metal partitioning in soluble, exchangeable, and reducible fractions indicated that Fe, Al, Cu, Zn, Pb, and Cd held in the water soluble and exchangeable phase represented a minor part of the total metal content. However, water soluble plus exchangeable Mn accounted for 19,10, and 1% of the total Mn in freshwater, brackish, and saltwater environments, respectively. Iron and manganese oxides were found to scavenge metals to 50% of the total heavy metal content.
Influence of Soil Animals and Metals on Decomposition Processes: A Microcosm Experiment
Authors: Bengtsson Goran , Berden Maria , Rundgren Sten
Published: July 2010

Metal pollution may reduce both the density and diversity of litter‐and mor‐living soil invertebrates. The consequences of this reduction for decomposition processes in coniferous forest soils were studied in a laboratory microcosm experiment, where the influence of soil fauna and metals were examined. Soil columns were prepared with litter, mor, and mineral soil, and the indigenous microorganisms from two field sites approximately 300 and 8000 m from a brass mill. The columns were used during a 10‐wk experiment with enchytraeids and microarthropods added. Presence of animals increased C and N mineralization and enhanced leaching of dissolved organic C and nutrients by 20 to 30%. All of the reduced mass lost due to metal pollution and 20 to 35% of the reduction in leachate quantities of organic C and inorganic nutrients could be explained by reduced animal activity. The calculated decomposition rate constants predicted a delay in decomposition in the metal‐polluted soil by a factor of 10. With five replicates, an 18% difference in mass lost due to a doubling of the background concentration of metals could be detected by the microcosm method with a probability of 0.90.
Fly Ash and Lime Amendment of Acidic Coal Spoil to Aid Revegetation
Authors: Taylor E. M. , Schuman G. E.
Published: July 2010

A greenhouse study was conducted to evaluate the effect of fly ash (0, 10, 20, 30, and 40 g kg−1 of spoil) and agricultural lime (0, 10, 20, 40, and 80 g kg−1 of spoil) on ameliorating the low pH of acidic coal mine spoils. Topsoil depths of 0, 10, and 20 cm placed over the spoil were also evaluated. Two crops of barley (Hordeum vulgare L.) were grown to evaluate effects of the amendments and topsoil on aboveground plant biomass, root biomass and distribution, and element content of the vegetation. All levels of lime and fly ash significantly increased the spoil pH, aboveground plant biomass, and root biomass. Topsoil placement over the spoil also generally increased plant biomass. Root growth in untreated spoil was limited to the depth of topsoil. However, when the spoil was amended with either fly ash or lime root growth occurred throughout the material. Fly ash and lime did not cause elemental toxicities to the plants, except for B. Although visual B toxicity symptoms and elevated levels of plant B were evident, no reduction in plant biomass occurred. The results indicate that fly ash is a feasible alternative to lime for treating acidic coal spoils in the region.
Tungsten Content of Soils, Plants, and Sewage Sludges in Iowa
Authors: Fu M. H. , Tabatabai M. A.
Published: July 2010

Information on the W content in environmental matrices is desired. Because of the antagonistic effect of W on Mo nutrition of plants and microorganisms, this study was conducted to assess the concentration of W in soils, plant materials, and sewage sludges in Iowa. Results showed that the total W in 18 soils ranged from 0 to 2 mg kg−1, with mean and median values of 0.89 and 0.88 mg kg−1, respectively. The corresponding values for 22 plant materials ranged from 0 to 0.35 mg kg−1, with mean and median values of 0.18 and 0.17 mg kg−1. Analysis of 44 sewage sludge samples from different wastewater‐treatment plants in Iowa showed that the concentration of this element varied from 0.5 to 62 mg kg−1, with mean and median values of 4.3 and 2.2 mg kg−1, respectively.
Nutritional Factors that May Influence Bioavailability of Cadmium
Authors: Fox M. R. Spivey
Published: July 2010

Cadmium accumulates slowly in the human body and a critically high level in the kidney can cause damage to the proximal renal tubule. Loss of Ca in the urine then contributes to extensive skeletal mineral loss. The bioavailability of Cd to animals and humans can be markedly affected by nutritional status and dietary intakes of essential and other nutrients. In general, deficiencies and excesses of interacting nutrients exacerbate and protect, respectively, against the adverse effect of Cd. These effects on bioavailability occur primarily via changes in intestinal absorption, although accelerated uptake by the kidney sometimes occurs. The chemical form of Cd that is consumed experimentally can also modify response. Many aspects of the relationships between Cd and nutrients are incompletely understood. From studies of population groups with high Cd intakes from certain foods, it appears that consumption of an adequate diet protects markedly againsthe adverse effects of Cd.
Sources of Nitrogen and Phosphorus in an Estuary of the Chesapeake Bay
Authors: Kunishi H. M.
Published: July 2010

This study examined the contribution of agriculture to the nutrient (N and P) concentrations in the Wye River, an estuarine tributary the Chesapeake Bay. The river drains a watershed that is devoted mainly to farming and is devoid of any sources of municipal and industrial wastes. Water samples were analyzed for NO3‐N + NO2‐N and molybdate‐reactive P (MRP). The concentrations of these forms nutrients were then examined in relation to sampling site, sample salinity, and time of year. Freshwater entering the river (brackish) from the watershed contained consistently high concentrations of NO3‐N (about 4 mg L−1) and low concentrations of PO4‐P (about 40 µg L−1). Once these nutrients entered the estuarine part of the river, however, the concentrations of NO3‐N decreased to low levels within a short distance (500–700 m) from the point of riverine discharge, through both dilution with brackish water and apparent microbial action. The concentrations of MRP increased markedly through release from within estuary sources. Concomitantly, the estuary released large quantities of NH4. The estuary itself, therefore, was the immediate major source of N (as NH4) and P.
Minesoil Property Effects on the Height of Ten‐Year‐Old White Pine
Authors: Torbert J. L. , Tuladhar A. R. , Burger J. A. , Bell J. C.
Published: July 2010

Thirty‐four 10‐yr‐old white pines (Pinus strobus L.) growing on reclaimed minesoils in Virginia were selected to evaluate the effects of selected minesoil properties on tree growth. A 1‐m deep backhoe pit was dug at the base of each tree to determine rooting depth, and surface soil samples (0–10 cm) were collected for analysis of selected physical and chemical properties. Multiple regression analysis was used to model the combined effects of minesoil properties on tree height. The minesoil variable that had the greatest influence on tree growth was rooting volume index, defined as depth to a restrictive layer times the soil‐sized fraction (%) of the surface 10 cm. The next most influential minesoil property that affected height was soluble salt content; an inverse relationship existed between tree height and electrical conductivity of a 1:5 soil/water extract. A linear regression equation describing white pine site index (SI50) as a function of the square root of depth to a restrictive layer was highly significant.
Radiochemical Analysis of Phosphorus Exchange Kinetics between Sediments and Water under Aerobic Conditions
Authors: Furumai H. , Ohgaki S.
Published: July 2010

Adsorption‐desorption reactions of P by lake sediments, Lake Kasumigaura, Japan, were studied using radioisotope 32P inorganic phosphate. Exchange rates and amounts of exchangeable P in sediments were measured in aerobic sediments‐water batch systems under different pH and P concentration conditions. Exchangeable P ranged from 6 to 43% of the total P in the indigenous sediments. Increasing pH induced P desorption from sediment. The relationship between the concentration in water and the amount of exchangeable P could be explained by the Langmuir equilibrium model. However, the Langmuir rate equation cannot describe the kinetics of whole exchange reactions. The adsorption‐desorption reaction was composed of an exchange reaction and a slow adsorbed‐reaction. The exchange reaction has two phases—very rapid reaction and a Langmuir‐type reaction.
Forest Harvest and Site Preparation Effects on Erosion and Sedimentation in the Ouachita Mountains
Authors: Miller E. L. , Beasley R. S. , Lawson E. R.
Published: July 2010

Soil erosion and sedimentation effects of three silvicultural treatments—clearcutting, selection cutting and no disturbance (control)—were compared in a replicated small watershed study conducted in the Ouachita Mountains of Arkansas on shallow soils derived from sandstones and shales. Clearcutting significantly increased annual sediment yields over selection and control treatments in 1981, the first year, after treatment but not in 1982 or 1983. Clearcut to control sediment yield ratios were 20:1, 6:1, and 2.6:1 in 1981, 1982, and 1983, respectively. First‐year sediment losses from clearcuts averaged 237 kg ha−1. Stream channels were stable, but they still may have been the primary source of the sediment losses. Erosion following harvest and site preparation did not exceed estimates of long‐term soil formation rates. Longterm soil losses were projected to average 70 kg ha−1 yr−1 over a 35‐yr rotation period with clearcutting while control rates were projected to average 50 kg ha−1 yr−1. A comparison of soil losses measured in this study with baseline rates and estimated soil loss tolerances suggests site productivity need not be threatened by silviculturally induced soil erosion. Suspended solids levels of stormflow were less than 100, 50, and 20 mg L−1 at least 99, 98, and 97% of the time, respectively, across treatments. Only at the 10 mg L−1 level was there a significant total suspended solids time differential in watershed stormflow between clearcut or selection cut and control treatments.
Retention of Cadmium by Several Soils of the Southeastern United States
Authors: King Larry D.
Published: July 2010

Since significant entry of Cd into the food chain is undesirable, soil properties important in reducing plant availability of Cd must be identified. Solubility of applied Cd in various extraction solutions is one estimate of plant availability. Cadmium nitrate was applied at rates supplying up to 1.25 mmol Cd kg−1 (140 mg kg−1) to soil from the A horizons and some B horizons of 10 mineral and three organic soils. The treated soils were incubated at 20 °C and at the end of 2, 4, and 8 weeks samples were withdrawn and extracted with 1 M KCl, Mehlich 1 (M1), and 0.2 M (NH4)2C2O4 [AO]. Length of incubation had no effect on the quantity of Cd removed by the extractants (extractability). Extractability was related linearly to Cd application rate but the effect of soil type on slope (extractable Cd/applied Cd) was more pronounced with KCl (110% variation in slopes) and AO (270%) than with M1 (27%). At the 1.25 mmol Cd kg−1 rate, KCl‐extractable Cd decreased with increasing pH but differences among soils were large. Stepwise multiple regression was performed using sand; silt; clay; pH; cation exchange capacity (CEC); exchangeable cations; organic matter; dithionite‐extractable Al and Fe; and AO‐extractable Al, Fe, and Mn as independent variables. Exchangeable Ca and pH were important soil properties related to extractability with the three extractants but values of R2 were < 0.8 even for three‐variable models. Since pH was the dominant factor, the data were grouped into pH increments of 0.5 and regression repeated. Exchangeable Ca, CEC, and dithionite‐extractable Al were important factors related to extractability, but values of R2 were < 0.6. Overall, the ability to estimate extractability from basic soil properties was low.
Formation of a Cemented Subsurface Horizon in Sulfidic Minewaste
Authors: McSweeney K. , Madison F. W.
Published: July 2010

In the early 1900s, Pb‐Zn ores in southwest Wisconsin were roasted for metal extraction. In the process, Fe‐bearing minerals were converted to a magnetic state for separation; metallic oxides were recovered and wastes consisting of about 30% Fe and 15% S, as well as numerous minor constituents, were deposited on the land surface in close proximity to the processing plants. Although the waste materials remain unvegetated today, significant changes have occurred in their mineralogical composition, which are reflected in the formation of discrete horizons. Micromorphological techniques were used to determine the pore space relationships of the unconsolidated material and the elemental and mineral distribution in the various horizons. Mineralogical transformations have been documented, which are largely dictated by the hydrology, porosity, and redox chemistry of the waste. The transformations include subsurface precipitation of mainly gypsum and Fe oxides and hydroxides in inter‐aggregate pores and mainly hydrated Fe‐sulfates such as copiapite and kalinite within intra‐aggregate pores. The net result is a dense, cemented horizon, which probably has a low permeability. The presence of this cemented layer has important implications for developing reclamation strategies, because it may form a potential barrier to transport of pollutants to the groundwater.
Selenium Uptake by Some Agricultural Crops from Central California Soils
Authors: Wan H. F. , Mikkelsen R. L. , Page A. L.
Published: July 2010

Greenhouse experiments were conducted to study Se uptake and partitioning by crops grown in five California soils of differing physical and chemical properties. Alfalfa (Medicago sativa L.), barley (Hordeum vulgare L.), beet (Beta vulgaris L.), and tomato (Lycopersicon esculentum Mill.) were grown in soil to which 0, 0.5, and 1.5 mg Se(VI) kg−1 was added. Alfalfa was also grown in four additional soils to which 0, 0.5, 1.5, and 3.0 mg Se(VI) kg−1 had been added. Plants were grown to maturity, separated into plant parts, and analyzed for yield and tissue Se. For the barley, beet, and tomato, the edible portion of the plant contained much less total Se than the generally inedible plant parts. The presence of soluble SO2−4 in the soil was the major soil factor in determining Se accumulation by plants. Alfalfa grown in low‐SO2−4 soil accumulated Se to a concentration 10 to 20 times greater (> 1000 mg Se kg−1) than plants growing in high‐SO2−4 soil (< 100 mg Se kg−1). When exposed to Se(VI) in the root zone, all plants tested were capable of accumulating Se to concentrations potentially harmful to animals.
Sulfate Mobility in an Acid Danish Forest Soil
Authors: von Freiesleben Niels Erik
Published: July 2010

A key question in the acidification of soils due to atmospheric deposition of strong acids is the accumulation of SO2−4 in the soil. Sulfate leaching was studied in the laboratory in undisturbed soil cores taken in a Typic Udipsamment under spruce forest. The soil cores were watered with natural throughfall water (pH 3.6) or with throughfall acidified to pH 3.3 or 2.8 with a mixture of sulfuric and nitric acid (1:1, molar basis). A total of 660 mm of throughfall was applied during 11 months. The technique of using soil cores produced increased nitrification and mineralization in the soil, causing a continuous acid production in the soil cores and decrease in the leachate pH during the experiments. Soil solution concentrations of SO2−4 were in the range 0.4 to 1.5 mmol L−1, total Al 0.2 to 1.5 mmol L−1, and pH 3.5 to 4.1. Stability diagrams using Al and SO2−4 activities and pH indicate that precipitation of a solid phase with the composition of AlOHSO4 may control the Al and sulfate activities in the soil solutions in the Bw horizon but not in the Ap horizon. The equilibrium constant for this basic Al sulfate was estimated at 20°C, pKs = 17.36 and at 5°C, pKS = 17.05. The 35S labeled SO2−4 was added once to the same soil cores followed by 15 mm throughfall per day (Natural or adjusted to pH 2.8). After application of 75, 150, or 225 mm of throughfall water the distribution of 35S‐SO2−4 in the soil cores was determined. From 38 to 100% of the applied 35S‐SO2−4 was retained in the soil cores and of this amount 32 to 63% was found in the top of the Bw horizon, which was highest in free Al and Fe oxides. The studied soil did not accumulate SO2−4 under ambient field conditions. In the laboratory, however, SO2−4 accumulation was demonstrated when the soil was exposed to increased SO2−4 load and temperature as well as decreased pH, showing that SO2−4 sorption/desorption may buffer variations in SO2−4 concentrations in soil solutions, and thereby delay effects of acidification on cation leaching.
Alternative Ozone Dose Metrics to Characterize Ozone Impact on Crop Yield Loss
Authors: Rawlings J. O. , Lesser V. M. , Heagle A. S. , Heck W. W.
Published: July 2010

Previous studies of the National Crop Loss Assessment Network (NCLAN) relating the impact of ozone (O3) on agricultural crops have used the seasonal arithmetic average of O3 for either a 7‐ or 12‐h daily period as the measure of dose in the dose response relationships. This study investigated the use of alternative dose metics that gave differential weighting to hourly O3 concentrations according to level of O3, period of day, or total hourly solar radiation. Data were used from two NCLAN studies in which two different methods of O3 addition were used for 7 h/d. In addition, one study included 12 h/d exposure for one method of O3 addition. The residual sums of squares from fitting a common Weibull response model to each experiment were compared over the range of dose metrics. The results suggested that the dose metrics using equal weighting of peaks and valleys closely reflected plant reaction to O3, but the fit of the dose‐response models improved if relatively little weight was given to the final 5‐h component (1700–2200 h EDT) of the 12‐h exposure period. Weighting by total hourly solar radiation gave results very similar to the best obtained from differential peak‐valley weighting and 7 h:5 h weighting.
Transformations of Nitrogen‐15‐Labeled Fertilizer Nitrogen and Carbon Mineralization in Incubated Coal Mine Spoils and Disturbed Soil
Authors: Reeder J. D.
Published: July 2010

Limited information is available concerning N transformations in exposed geologic materials of disturbed lands in the western USA. A laboratory incubation study was therefore conducted using 15N to trace the dynamics of fertilizer 15NH+4 added to samples of one topsoil and five coal mine spoils from Colorado and Wyoming. Carbon dioxide evolution, N mineralization, nitrification, microbial immobilization, and NH+4 fixation within clay minerals were monitored over time. The organic matter in three of the spoils was considerably less susceptible to microbial decomposition than the topsoil organic matter, whereas the organic matter in the fourth spoil was slightly less susceptible than, and in the fifth spoil comparable to, topsoil organic matter in susceptibility to microbial decomposition. However, the amount of plant‐available N mineralized was at least five times higher in the topsoil than in any of the spoil materials. The data suggest that, under field conditions, none of the spoil materials evaluated in this study will likely be able to adequately supply the N requirements of a reseeded plant community. The significantly more active microbial population of the topsoil immobilized more of the added 15NH+4 than in any of the spoils except the shale, whereas more of the added 15NH+4 was nitrified and remained as NO−3 in the spoils than in the topsoil. The data indicate that under field conditions, a larger proportion of added fertilizer NH+4 will be susceptible to loss via NO−3 leaching or volatilization in the spoils than in the topsoil.
Chemical and Decomposition Characteristics of Anaerobic Digester Effluents Applied to Soil
Authors: Sweeney D. W. , Graetz D. A.
Published: July 2010

A study was conducted to determine the elemental concentrations of an effluent that resulted from the anaerobic digestion of rum distillery by‐products (also called molasses residue) and decomposition characteristics in soil as measured by CO2 evolution. For comparison, two additional effluents from the anaerobic digestion of swine wastes and bovine wastes were included (Susscrofa and Bos taurus, respectively). The carbon content of oven‐dry molasses residue and swine waste effluents were both approximately 250 g kg−1, whereas the bovine waste was 152 g kg−1. The molasses residue effluent sample had a greater K concentration on an oven‐dry basis than the swine or bovine waste materials. However, the concentrations of most other elements were higher in the swine waste effluent. In contrast, higher solute concentrations were found for most elements in the molasses residue effluent than in the swine waste effluent. An analysis of variance performed on total CO2‐C evolved after 20 d as well as at the end of the experiment (117 d) indicated an interaction between effluent source and rate. This was caused by the low amount of CO2 evolved from soil amended with the bovine waste effluent regardless of application rate. At day 20, cumulative CO2 evolution was higher with the molasses residue effluent than with the swine waste effluent; however, by day 117, only at the high application rate was CO2 evolution higher with the molasses residue. Lower application rates allow for proportionally more short‐term decomposition of the molasses residue and swine waste effluents than at higher rates. Although effluent sources result in different amounts of total evolution, between 40 and 50% of the total CO2 evolved may occur in the first 20 d.
The Fate of Nitrogen from Injected Liquid Manure in a Silt Loam Soil
Authors: Comfort S. D. , Kelling K. A. , Keeney D. R. , Converse J. C.
Published: July 2010

A field experiment was conducted on a Piano silt loam (Typic Argiudoll) in southcentral Wisconsin to monitor N transformations following liquid manure injections. Liquid manure with and without a nitrification inhibitor [nitrapyrin, 2‐chloro‐6‐(trichloromethyl)pyridine, 13 mg a.i. L−1 liquid manure] was injected into an uncropped area in June 1985. Soil samples were taken using a grid placed over the vertical cross‐section of the injected bands permitting spatial sampling in the vertical plane. Sampling was done 5, 12, 26, 39, 67, 99, and 350 d after manure application by progressive exposure of the band. Soil water content, pH, NH4‐N, (NO2 + NO3)‐N, Cl, and water‐soluble C were determined. The synagraphic computer program, SYMAP, was used to evaluate spatial changes in inorganic N concentrations in the manure injection zone. Nitrapyrin was not effective in inhibiting nitrification at the rate used. Nitrification occurred at the outer fringes of the band within 5 d; maximum concentrations of 300 to 800 mg NO3‐N kg−1 occurred throughout the injection zone at 26 d. High respiratory activity in the injection zone was indicated by an almost threefold decrease in water‐soluble C between day 5 (750 mg C kg−1) and day 12 (270 mg C kg−1). Water content remained higher than the surrounding soil in the injection zone for 99 d. Once NO3 leaching occurred, NO3‐N/Cl ratios decreased with depth under the injection zone. The abundant supply of NO3 and readily oxidizable C, combined with the high moisture environment, led to the conclusion that liquid manure injections created an environment conducive for denitrification.
Sensitivity of Plants to Acidic Fog
Authors: Musselman R. C. , Sterrett J. L.
Published: July 2010

Several crop species were exposed to simulated acidic fog from pH 1.6 to 3.2 or to 5.6 in greenhouse experiments. Foliar injury and growth of radish (Raphanus sativus L. cv. Cherry Belle), tomato (Lycopersicon esculentum Mill. cv. Tiny Tim), onion (Allium cepa L. cv. Southport White Globe), spinach (Spinacia oleracea L. cv. Bloomsdale Long Standing), bean (Phaseolus vulgaris L. cvs. Pinto and Improved Kentucky Wonder), alfalfa (Medicago sativa L. cvs. Mesa Sirsa and Moapa 69), sweet orange (Citrus sinensis L. cv. Valencia), and trifoliate orange (Poncirus trifoliate L.) were determined after exposure to simulated fog at acidites down to pH 1.6. Potted plants were exposed for 2 h after sunset on 2 consecutive days every week for 4 (radish) or 12 (others) weeks. Acidic fog at ambient pH levels injured plants, but large amounts of acidic input were required for injury to occur. Although crop species varied in magnitude of response to acidic fog, in general, pH 3 or below was required to induce foliar injury and pH 2 or below was required to induce foliar injury and pH 2 or below to reduce growth. Radish, spinach, alfalfa, and Valencia orange were sensitive to foliar necrosis from acidic fog, while onion was tolerant. Acidic fog reduced yields of dry bean and spinach, reduced root weight of tomato, and delayed maturity of bean and alfalfa.
Effects of Sludge Application Sequence on Carbon and Nitrogen Mineralization in Soil
Authors: Wiseman John T. , Zibilske L. M.
Published: July 2010

A laboratory experiment was conducted to determine the effects of an initial sludge amendment on C and, primarily, N mineralization of a second sludge amendment. In this study, a municipal sludge containing Cr‐tanning effluent, and a domestic sludge with little metal contamination were added to a sandy loam soil at rates of 6.65 g domestic sludge kg−1 soil and 9.75 g municipal sludge kg−1 soil. Sludges were reapplied 40 d later at the same rates in all sequence combinations. Respiration and nitrification were increased in sludge‐amended soil. At least 70% of the total C mineralized from both sludges was evolved within the first 11 d. Initial sludge application had little effect on C evolution from subsequent applications. Nitrogen mineralized from sludge‐amended soils during the initial 40 d of incubation was linearly related to time. A second application of sludge did not change the linear nature of N mineralization in all but one treatment. Ammonium N rapidly decreased and was negligible 2 weeks after sludge addition. Nitrite nitrogen levels were negligible throughout the experiment. By the end of the incubation period, the quantity of nitrate produced in all sequences of sludge addition was similar. Results indicate little effect of initial sludge addition on C and N mineralization of a second sludge amendment, even if the initial sludge applied contained a high concentration of Cr.
Impact of Ozone on the Growth and Yield of Trees: A Review
Authors: Pye John M.
Published: July 2010

Data from 25 experiments on seedlings of 43 tree species and hybrids show that ozone (O3) can reduce growth and photosynthesis at concentrations common in many areas of the USA. Seedlings have been primarily employed for such studies for logistic reasons, and will likely provide the greatest breadth of information for some time to come. However, a number of impediments limit application of seedling response studies to assessment of impacts on regional timber production. Large trees differ from seedlings in a number of ways, including C allocation and canopy structure, and methods must be developed to account for these differences if information from seedling studies is to prove useful to forest impact assessment. Understanding how competition mediates individual tree responses will require investigation of whether systematic differences of microclimate leaf morphology that exist across canopies affects foliage sensitivity to O3, and whether the maximum growth rates of genotypes are correlated with susceptibility to O3. Definitive information on these factors is necessary to assess impacts of O3 on stand development and diameter distributions in both multi‐ and single species stands. Of critical economic importance is whether O3 preferentially damages taller, more valuable individuals within stands and more valuable, faster growing stand types.
Septic System Performance on a Coastal Barrier Island
Authors: Cogger C. G. , Hajjar L. M. , Moe C. L. , Sobsey M. D.
Published: July 2010

A field experiment was conducted on a Corolla fine sand (Aquic Quartzipsamment) to evaluate wastewater treatment by septic systems under conditions typical of Atlantic coastal barrier islands. The effects of loading rate and water table depth on wastewater treatment were studied. Two absorption fields were installed and were designated the upper and lower fields based on their relative topographic locations. The trenches in the lower field were 30 cm closer to the water table than the trenches in the upper field. Each field consisted of nine absorption trenches. Three loading rates (1, 4, and 16 cm d−1) were each replicated three times in a completely randomized design. Groundwater samples around the trenches were collected biweekly from shallow wells (1.5–1.9 m deep) between May 1982 and December 1983, and were analyzed for NO−3‐N, NH+4‐N, soluble P, Na+, Cl−, K+, and fecal coliform bacteria. During the first year the water table was within 30 cm of the lower field trenches 20% of the time, and anaerobic conditions prevailed. Groundwater samples collected adjacent to the trenches contained predominantly NH+4‐N, fecal coliform counts averaged over 25 000 MPN (most probable number) L−1, and the redox potential averaged <300 mV. During the second autumn the lower field showed aerobic tendencies due to drier weather and a deeper water table. The upper field remained aerobic throughout, with almost complete nitrification occurring. Average fecal coliform counts were reduced to 60 MPN L−1, and the mean redox potential was >500 mV. The wastewater loading rate had a significant effect on the levels of all constituents, but the loading rate effect was smaller than the water table effect. Phosphorus movement appeared to be related to pore‐water velocity.
Sorption and Degradation of Aldicarb and its Oxidation Products in a Soil‐water Flow System as a Function of pH and Temperature
Authors: Lemley A. T. , Wagenet R. J. , Zhong W. Z.
Published: July 2010

The sorption and degradation of aldicarb [2‐methyl‐2‐(methylthio) propionaldehyde O‐(methylcarbamoyl)oxime], aldicarb sulfoxide [2‐methyl‐2‐(methylsulfinyl)propionaldehyde O‐(methylcarbamoyl)oxime], and aldicarb sulfone [2‐methyl‐2‐(methylsulfonyl)propionaldehyde O‐(methylcarbamoyl) oxime] in a sandy loam soil were determined under varying pH and temperature conditions. The experiments were performed using a soil‐column methodology, which allows a steady state water flow and nonsteady state addition of pesticide. The edition curve (concentration vs. time) was interpreted using analytical solutions to the convection‐dispersion equation that included linear sorption and pseudo‐first‐order degradation. The sorption of the three species changes slightly with pH over the range studied (pH 5–8).The degradation varies with pH, but not in the same manner as found in aqueous solution studies. Sorption decreases as the temperature is increased from 15 to 35°C. Degradation is also temperature dependent in this range and for aldicarb sulfone can be represented by a linear Arrhenius plot from which activation energies can be derived. There is good agreement between the calculated activation energy for aldicarb sulfone and that obtained in aqueous solution studies. The results of this study have provided information about the thermodynamics of the aldicarb system and have demonstrated the usefulness of the soil‐column flow method as a good laboratory model for chemical transport and transformation in soil.
Nitrogen Mineralization Kinetics in Soil During Long‐term Aerobic Laboratory Incubations: A Case Study
Authors: Bonde Torben A. , Lindberg Torbjorn
Published: July 2010

Literature data describing curves of cumulative net N mineralization characterized by an initial lag‐phase and obtained by long‐term (26 weeks) aerobic laboratory incubations were fitted to different regression models by means of nonlinear regression analysis. The model offering the most appropriate description of the data were selected on the basis of the residual sum of squares left unexplained by the regression. The models employed and compared to the classical first‐order model were a mixed‐order, one‐component model: urn:x-wiley:00472425:equation:jeq2jeq198800472425001700030011x-math-0001 a mixed/first‐order, two‐component model: urn:x-wiley:00472425:equation:jeq2jeq198800472425001700030011x-math-0002 and a simplified special case of the previous, mixed/linear, two‐component model: urn:x-wiley:00472425:equation:jeq2jeq198800472425001700030011x-math-0003 where Nm and N0 are the amount of mineralizable N present in the soil at time t and time 0; Na and Nr are the amounts of mineralizable N initially present in the available and resistant fractions, respectively; ti equals length of incubation; rate constants h1 and h2 belong to the mixed‐order model; k is a first‐order rate constant; and C denotes the slope of the linear tail following the pattern described by the mixed‐order expression. Data from three soils, unamended or amended with manure, were best described by the mixed/first‐order or, alternatively, the mixed/linear model. The fit was significantly better than that offered by the classical first‐order, one‐component model. The prediction of potentially mineralizable nitrogen (N0) varied between 108 and 240 mg N kg−1 soil in an unamended soil, depending on the choice of model