bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors Affecting Preferential Flow of Water and Atrazine through Earthworm Burrows under Continuous No‐Till Corn
Authors: Edwards W. M. , Shipitalo M. J. , Owens L. B. , Dick W. A.
Published: July 2010

Watershed studies have documented that summer storms produce less runoff from fields farmed with continuous no‐tillage corn (Zea mays L.) than from the same soils when corn is produced with conventional tillage practices. The lack of tillage favors a continuous surface cover of crop residue and the persistence of earthworm burrows, which have been shown to be preferential flow paths for water and chemicals, especially during intense summer storms. We investigated factors affecting preferential water and chemical transport in burrows formed by the earthworm Lumbricus terrestris (L.) in the field using individual burrow samplers and in the laboratory using blocks of undisturbed soil subjected to simulated rainfall. Rainfall amount and intensity and antecedent soil moisture content affected the amount of water transmitted in earthworm burrows, with high intensity storms on relatively dry no‐till soils producing the greatest amounts of preferential flow. Atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine) transport was affected by the factors influencing the amount of preferential flow and by the time of storms relative to the time of herbicide application. Atrazine movement in earthworm burrows was greatest when high‐intensity rainfall occurred shortly after application. Atrazine transport was reduced by a delay in rainfall and by low‐intensity events prior to high intensity, percolate‐producing events.
Nutrient Interception by a Riparian Forest Receiving Inputs from Adjacent Cropland
Authors: Jordan Thomas E. , Correll David L. , Weller Donald E.
Published: July 2010

To investigate the ability of riparian forest to intercept nutrients leaving adjacent cropland, we examined changes in the chemistry of groundwater flowing from a corn (Zea mays L.) field through a riparian forest. This study provided a comparison to previous studies of a different forest. We sampled groundwater from a transect of wells, and used a Br− tracer to confirm that groundwater moved laterally along the transect through the forest. As groundwater flowed through the forest, NO−3 concentrations decreased from about 8 mg/L at the edge of the corn field to <0.4 mg/L halfway through the forest. Dissolved organic N and NH+4 increased by less than 0.1 mg/L, and dissolved organic C did not change with distance. Sulfate remained constant with distance until midway through the forest, where it began to increase. Chloride concentration rose until midway through the forest, then fell. Values of pH increased from under 5 at the edge of the corn field to over 7 at the stream bank, perhaps as a result of the NO−3 consumption. Most of the change in NO−3 occurred abruptly at the edge of a floodplain within the forest. There the water table was closest to the surface and soil Eh below the water table was less than −90 mV. Such strongly reducing conditions may have promoted denitrification in the floodplain. In contrast, soil Eh on the adjacent hill slope was above 500 mV, too high to support denitrification. There were only slight seasonal changes in groundwater chemistry. We also studied the net annual accretion of sediment in the riparian forest by measuring changes in the elevation of the soil surface. There was little or no accretion in the forest, but along a path of overland storm flow there was net erosion. Thus, nutrient retention by this forest, in contrast with the forest we previously studied, was entirely a below ground process. Functional differences within sections of this forest and among different riparian forests suggest a need for research on the factors that control nutrient retention.
Determining Off‐Site Concentrations of Volatile Pesticides Using the Trajectory‐Simulation Model
Authors: Yates S. R.
Published: July 2010

An environmental transport model is described and illustrated that will enable the prediction of the mass and/or concentration of volatile pesticides at any depth in the soil profile and at any height in the atmosphere relatively far distanced downwind from agricultural fields. The theoretical profile shape model is used to determine transport in the atmosphere and is coupled to the behavior assessment model (BAM) to describe transport in soils. The model outputs include the soil‐water concentrations, the surface volatilization rate, the concentration of pesticides in the atmosphere above the field, and the atmospheric concentration at specified distances downwind from the field. The results from this approach can be used in exposure assessment studies to determine the risk for individuals living near agricultural fields.
Sorption of Cadmium and Lead by Clays from Municipal Incinerator Ash—Water Suspensions
Authors: Roy W. R. , Krapac I. G. , Steele J. D.
Published: July 2010

The effect of Cl complexation in extracts of a flue gas‐scrubber incinerator fly ash sample on the sorption of Cd and Pb by kaolinite and illite was investigated using batch‐sorption methods. In the pH range of 5 to 9, Cl complexation may reduce sorption and thus increase the mobility of these metals. When an ash—water suspension was acidified to pH 6.85, the dissolution of Cl and Ca essentially eliminated Cd sorption because of complexation and cationic competition. Cadmium would be considered as either mobile or very mobile under these conditions. Lead was not soluble in the pH‐6.85 suspension. At pH 12, the approximate pH of water in contact with flue gas‐scrubber fly ash, Cd was essentially insoluble and Pb occurred as anionic Pb hydroxide. Anionic Pb was sorbed by the two clays, and the extent of sorption was not influenced by Cl or carbonate complexation. Sorption constants, derived from isotherms, suggested that Pb would be relatively immobile in saturated soil—water systems. The recent concern that highly alkaline, flue gas‐scrubber fly ash may release environmentally significant concentrations of mobile Pb when placed in an ash‐disposal site with a soil liner should be reevaluated in light of this study.
Modeling of Oxygen Transport and Pyrite Oxidation in Acid Sulphate Soils
Authors: Bronswijk J. J. B. , Nugroho K. , Aribawa I. B. , Groenenberg J. E. , Ritsema C. J.
Published: July 2010

Drainage and aeration of previously submerged acid sulphate soils could lead to oxidation and acidification of the soil and to related problems such as high Fe and Al concentrations in the soil solution. Agricultural production on these acidified soils is low. Furthermore, leaching of acid and toxic compounds from the soil to surface waters may cause environmental damage, such as degradation of ecologically valuable wetlands. A computer simulation model was developed to compute the rate and magnitude of pyrite oxidation in pyritic deposits such as acid sulphate soils, and the resulting acidity, soluble Fe and sulphates produced. The model includes vertical gaseous O2 diffusion from the atmosphere into the soil macropores, lateral diffusion of dissolved O2 into the soil matrix, and O2 consumption inside the soil matrix by pyrite oxidation and organic matter decomposition. Oxygen consumption by pyrite oxidation was modeled by combining the equal diameter reduction model with an O2 concentration dependent rate constant for pyrite oxidation. The model was validated by comparing computations and measurements in an acid sulphate soil subjected to drainage for a period of 440 d. Computed and measured pyrite content profiles, gaseous O2 concentrations in the macropores and sulphate concentrations in the soil solution corresponded well. The present model, combined with a chemical equilibrium model and a solute transport model, can be applied to predict the (long‐term) effects of water management strategy on the quality of soils, drainage waters and surface waters in areas with pyritic deposits.
Anatomical, Chemical, and Ecological Factors Affecting Tree Species Choice in Dendrochemistry Studies
Authors: Cutter Bruce E. , Guyette Richard P.
Published: July 2010

Recently, element concentrations in tree rings have been used to monitor metal contamination, fertilization, and the effects of acid precipitation on soils. This has stimulated interest in which tree species may be suitable for use in studies of long‐term trends in environmental chemistry. Potential radial translocation of elements across ring boundaries can be a confounding factor in assessing environmental change. Thus, the selection of species which minimizes radial translocation of elements can be critical to the success of dendrochemical research. Criteria for the selection of species with characteristics favorable for dendrochemical analysis are categorized into (i) habitat‐based factors, (ii) xylem‐based factors, and (Hi) element‐based factors. Species with a wide geographic range and ecological amplitude provide an advantage in calibration and better controls on the effects of soil chemistry on element concentrations. The most important xylem‐based criteria are heartwood moisture content, permeability, and the nature of the sapwood‐heartwood transition. The element of experimental interest is important in determining which tree species will be suitable because all elements are not equally mobile or detectable in the xylem. Ideally, the tree species selected for dendrochemical study will be long‐lived, grow on a wide range of sites over a large geographic distribution, have a distinct heartwood with a low number of rings in the sapwood, a low heartwood moisture content, and have low radial permeability. Recommended temperate zone North American species include white oak (Quercus alba L.), post oak (Q. stellata Wangenh.), eastern redcedar (Juniperus virginiana L.), old‐growth Douglas‐fir [Pseudotsuga menziesii (Mirb.) Franco] and big sagebrush (Artemisia tridentata Nutt.). In addition, species such as bristlecone pine (Pinus aristata Engelm. syn. longaeva), old‐growth redwood [Sequoia sempervirens (D. Don) Endl.], and giant sequoia [S. gigantea (Lindl.) Deene] may be suitable for local purposes.
Influence of Cattle‐Manure Slurry Application on the Solubility of Cadmium, Copper, and Zinc in a Manured Acidic, Loamy‐Sand Soil
Authors: del Castilho P. , Chardon W. J. , Salomons W.
Published: July 2010

The concentrations of Cd, Cu, and Zn were evaluated bimonthly in the soil solution of five acidic loamy‐sand soil plots during an 18‐mo period, before and after application of 25 Mg ha−1 cattle‐manure slurry on top of the plots. pH, Cd, Zn, Cu, and Fe concentrations, electrical conductivity (EC), and dissolved organic carbon (DOC) were monitored in the soil‐solution samples extracted from soil down to 80‐cm depth. Dissolved metal concentrations ranged from 9 × 10−7 to 9 × 10−5 mmol m−3 for Cd, from 0.14 to 33 mmol m−3 for Zn, from 0.005 to 5 mmol m−3 for Cu, and from 0.54 to 4.6 × 10−3 mmol m−3 for Fe. Maximum soil solution concentrations of Cd (9 × 10−5 mmol m−3) and Zn (33 mmol m−3) were found between 0‐ and 40‐cm depth 6 wk after cattle‐manure slurry application; Cu and Fe concentrations were not elevated. Except for the peak concentrations of Cd and Zn following the cattle‐manure slurry application, no statistically significant temporal trends in heavy metal concentrations were observed. Multiple linear regression analysis showed a positive correlation between the metal concentrations with DOC and a negative correlation with pH. High EC levels in topsoil layers, resulting from manuring were also found to increase metal concentrations. In the topsoil the Cd and Zn concentrations were affected by soil solution pH, and in the subsoil by DOC variations. The Cu concentration was affected by DOC variations in all soil layers. Supercentrifugation of selected subsoil samples from one sampling date removed 80% of the Cd, Zn, and Cu from the solution along with DOC and Fe. Cation‐exchange column experiments as well as anodic stripping voltammetry measurements (speciation) of selected soil solution samples, showed that 30 to 70% of the dissolved Cu and all Cd was bound in relatively fast dissociating metal complexes. The observed variations in soil solution heavy metal concentration and speciation show that a distribution coefficient that describes the partition of metals over soil solution and solid phase is not a constant but depends on the physicochemical situation.
Influence of Freeze‐Thaw and Flooding on the Loss of Soluble Organic Carbon and Carbon Dioxide from Soil
Authors: Wang F. L. , Bettany J. R.
Published: July 2010

Freeze‐thaw and flooding significantly affected the loss of water soluble organic carbon (SOC) and carbon dioxide carbon (C‐CO2) from a well‐drained Black Chernozemic soil (Udic Boroll) in a leaching‐incubation study. At the end of 12 wk, the total loss of SOC was 90, 107, 399, and 224 mg kg−1 for soils with normal (incubated at field capacity moisture), freeze‐thaw, flooding and flooding‐freeze‐thaw treatments, respectively. The E4/E6 values of the leachates obtained from the four treatments ranged from 10 to 32, suggesting that SOC in the leachates was mainly low molecular weight in nature. The rate of the SOC leaching changed over time and the amount of SOC leached from the flooded treatments reached a maximum in the middle of the incubation period. In contrast, the rate of SOC leaching for unflooded treatments appeared little changed with no distinctive rate maximum. The cumulative loss of C‐CO2 and total C (sum of SOC and C‐CO2) from the treatments decreased in the order of flooding > normal > flooding‐freeze‐thaw > freeze‐thaw. The rates of C‐CO2 evolution decreased with time for the freeze‐thaw treated soils whereas the rate of C‐CO2 evolved from the normal treatment initially decreased and then increased after 8 wk of incubation, suggesting transient kinetics for the system. For the flooding treatment, the rate of C‐CO2 evolution showed a similar pattern to that of SOC leaching. There was a high linear correlation between the cumulative C‐CO2 evolved and SOC leached from the soil.
Storage and Migration of Fallout Strontium‐90 and Cesium‐137 for Over 40 Years in the Surface Soil of Nagasaki
Authors: Mahara Yasunori
Published: July 2010

The vertical migration of 90Sr and 117Cs produced by the explosion of the atomic bomb in 1945 was investigated in an unsaturated soil layer in the Nishiyama area of Nagasaki. The in situ migration rates of 90Sr and 137Cs were estimated to be 4.2 mm yr−1 and 1.0 mm yr−1, respectively, when the rate of movement of soil water was 2500 mm yr−1. The in situ Kd values of 90Sr and 137Cs were calculated to be 0.3 m3 kg−1 and 1.2 m3 kg−1, respectively. These are probably the only results that exist for the interaction between soil and 137Cs and 90Sr over 40 yr. These results suggest that since fallout 137Cs and 90Sr have remained in the surface soil for a long period of time, we should pay significant attention to radiological effects of nuclear accidents such as the Chernobyl disaster.
Accumulation of Cesium‐137 and Strontium‐90 in Ponderosa Pine and Monterey Pine Seedlings
Authors: Entry James A. , Rygiewicz Paul T. , Emmingham William H.
Published: July 2010

Because ponderosa pine [Pinus ponderosa (Dougl. ex Laws)] and Monterey pine (P. radiata D Don) have exceptionally fast growth rates and their abscised needles are not readily dispersed by wind, these species may be valuable for removing radioisotopes from contaminated soils. Ponderosa and Monterey pine seedlings were tested for their ability to accumulate 137Cs and 90Sr—characteristic radioisotopes of nuclear fallout—from contaminated soil. Seedlings were grown for 3 mo in 165 cm3 sphagnum peat moss/perlite (1:1 V/V) in a growth chamber. In Exp. 1, seedling accumulation of 137Cs and 90Sr after 1 mo of exposure was measured. In Exp. 2, seedling accumulation of the radioisotopes during different‐length exposures was measured. Seedling accumulation of 137Cs and 90Sr at different concentrations of the radioisotopes in the growth medium was measured in Exp. 3. Ponderosa pine accumulated 6.3% of the 137Cs and 1.5% of the 90Sr present in the growth medium after 1 mo; Monterey pine accumulated 8.3% of the 137Cs and 4.5% of the 90Sr. Accumulation of 137Cs and 90Sr by both coniferous species was curvilinearly related to duration of exposure. Accumulation of 137Cs and 90Sr by both species increased with increasing concentration in the growth medium and correlated curvilinearly with radioisotope concentration in the growth medium. Large areas throughout the world are contaminated with 137Cs and 90Sr as a result of nuclear weapons testing or atomic reactor accidents. The ability of trees to sequester and store 137Cs and 90Sr introduces the possibility of using reforestation to remediate contaminated soils.
Biogeochemical Responses of a Forested Watershed to Both Clearcut Harvesting and Papermill Sludge Application
Authors: Kraske C. R. , Fernandez I. J.
Published: July 2010

The biogeochemical responses of a forested watershed to both clearcut harvesting and papermill sludge application were evaluated. A mixed northern hardwood and conifer stand in Letter E Township, ME, was clearcut during the winter of 1985–1986. Harvest residues were windrowed, and red pine (Pinus resinosa Aiton) seedlings were planted. In 1987, herbicide was applied to reduce vegetative competition. In the fall of 1989, a combined primary and secondary papermill sludge was operationally applied with a rate of 40 Mg ha−1 (dry sludge). Actual loading rates varied considerably. Study plots were established in sludge‐harvest, control‐harvest, and uncut forest zones. Soils within the treatment zones consisted of Typic Haplorthods developed from loamy basal tills. Selected soil and soil solution properties were measured in 1989 and 1990. In 1989, harvest area forest floor pH was 0.6 to 0.8 units higher, and organic matter content was up to 40% lower, when compared with that of the uncut forest area. This reflected the accelerated decomposition of the forest floor as a result of the harvest activities. Sludge application further increased forest floor pH by approximately one unit, exchangeable Ca2+ and Mg2+ by ≈100 and 60%, respectively, cation‐exchange capacity by 60%, and base saturation by 34% compared with that of the control‐harvest area. Exchangeable Mg2+ and Na+, and water‐soluble SO2−4 were the mineral soil properties most affected by sludge application. Harvesting increased concentrations of major nutrients in soil solution. In 1989, solution Ca2+ was two to three times greater, and Mg2+ was three to six times greater in the harvest area than in the uncut forest area. Flushes of Ca2+, Mg2+, Na+, and SO2−4 into soil solution occurred immediately following sludge application. Only N+ and SO2−4 remained elevated in 1990, being five and three times greater, respectively, in the sludge amended harvest area than in the uncut forest area. Compared with the harvest operations, one‐time papermill sludge application appeared to have only small effects on the biogeochemical processes of the treated Letter E site.
Irrigation and Polymer Effects on Herbicide Transport through the Unsaturated Zone of a Sparta Sand
Authors: Wietersen R. C. , Daniel T. C. , Fermanich K. J. , Lowery B. , McSweeney K.
Published: July 2010

State‐sponsored monitoring programs show that the Sparta sand (sandy, mixed, mesic Entic Hapludoll) of the Lower Wisconsin River Valley (LWRV) is susceptible to herbicide movement through the vadose zone, especially atrazine [2‐chloro‐(4‐ethylamino)‐6‐(isopropylamino)‐s‐triazine]. Experiments were initiated to examine the effect of irrigation scheduling and pesticide formulation on transport through the vadose zone. Intact Sparta sand (SP) columns were extracted from the LWRV and instrumented to simulate temperature, irrigation and drainage conditions encountered in the field. Labeled 14C‐atrazine, alachlor [2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxymethyl) acetamide], and metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl) acetamide] were monitored in the leachate. Treatments included irrigation schedules to match no‐irrigation or rainfed (RF), evapotranspiration (ET) and ET plus an additional 25% (ET +). Formulation treatments consisted of standard pesticide tank‐mix mixtures with and without the addition of a polymer (2% by volume). Increased water input significantly increased metolachlor transport through the SP profile. Due to variability in the leachate data, no significant differences in the total amount of atrazine leached through the columns were shown to exist between the ET and ET + treatments; however, after initial irrigation, atrazine concentration in leachate from ET + treatment was 10 to 15 times greater than leachate of the ET treatment. When compared to the standard herbicide formulation, the use of the polymer significantly reduced and delayed the peak concentrations of metolachlor in the leachate. A significant difference also was observed in the amount of metolachlor retained in the surface soil (0–10 cm) of those columns receiving the polymer treatment compared to those receiving the standard application of the herbicide.
Selenite and Selenate Quantification by Hydride Generation‐Atomic Absorption Spectrometry, Ion Chromatography, and Colorimetry
Authors: Blaylock Michael J. , James Bruce R.
Published: July 2010

The need for a routine, inexpensive method with nanomolar detection limits for soluble SeO2−3 and SeO2−4 is increasing as Se research on soil‐plant‐water systems intensifies and speciation of Se valence states is required. This study was undertaken to compare hydride generation‐atomic absorption spectrometry (HGAAS), colorimetry using 2,3‐diaminonaphthalene (DAN), and ion chromatography (IC) as suitable methods for analysis of SeO2−3 and SeO2−4 in soil extracts and water samples. Selenium standards in solutions of either 1.0 mM KH2PO4, CaSO4, and KNO3, or in distilled water were analyzed to determine detection limits (DL), limits of quantitation (LOQ), and practicality for routine use of the above methods. A 0.1 mM K2HPO4/KH2PO4 soil extract spiked with 2.0 or 20 µM SeO2−3 and SeO2−4 was also used to compare the precision of the three methods. The HGAAS method was the most sensitive (0.212 absorbance units/µM) and had the lowest DL for SeO23 (0.03 µmol Se/L) of the three methods employed. Detection limits for the DAN and IC methods were significantly higher (18 and 0.24 µmol Se/L, respectively). Poor reproducibility between methods was obtained for SeO2−4 content of the soil extract containing 20 µM SeO2−4, with concentrations ranging from 9.1 ± 1.2 µmol/L determined by HGAAS to 24.6 ± 0.05 µmol/L by IC. The variability and poor recovery of SeO2−4 was due to variabilty in efficiency of the HCl reduction required to reduce SeO2−4 to SeO2−3 before analysis in the HGAAS and DAN procedures. Selenium determinations in samples where low detection limits (<0.1 µM) are required are most effectively accomplished with HGAAS. Colorimetry requires greater effort and time from the analyst to obtain the low detection limits of HGAAS, but is useful in that only a visible light spectrometer is required. Ion chromatography is capable of automated determinations of Se2−3 and SeO2−4 directly in combination with other ions of interest and may be appropriate for soil solution Se analysis where Se speciation is required.
Water Resource Implications of Midwest Agroecosystems
Authors: Oberle Steven L. , Burkart Michael R.
Published: July 2010

Agriculture contributes to nonpoint‐source pollution of the nation's water resources through leaching and runoff of crop nutrients, pesticides, and animal wastes, and through soil erosion from cropland. Development of effective solutions to water quality problems resulting from agricultural activities requires input of information synthesized from many disciplines, and coordination and integration of various scientific and technical programs. This article describes a program for synthesizing information resulting from USDA, USEPA, and USGS projects into evaluations of the regional impact of existing and innovative agroecosystems on surfacewater and groundwater quality. The program involves two facets with equal function and importance: assembling and analyzing information to characterize Midwest agroecosystems and to estimate water quality response; and developing effective systems for disseminating information and technology to end users. Four phases are presented as sequential, interdependent components of the program: (i) information acquisition and assessment; (ii) synthesis and systems development; (iii) education and technology transfer; and (iv) evaluation. Integration of information from water quality programs in the Midwest will provide a comprehensive and regional analysis, and can serve as the basis for disseminating information and technology necessary to implement agricultural management systems with maximum potential for protecting water resources. Regional analysis can also serve as input into the development of agricultural policy that is compatible with the nation's environmental and fiscal goals.
Modeling Alternatives to Reduce Dairy Farm and Watershed Nonpoint Source Pollution
Authors: Sugiharto Toto , McIntosh T. H. , Uhrig R. C. , Lardinois J. J.
Published: July 2010

Management practices are available that may reduce sediment or phosphorus (P) loading to streams draining agricultural land. An evaluation of the long term effects of implementing one or more of these practices is needed. We used the Erosion Productivity Impact Calculator (EPIC) and Agricultural Non‐Point Source (AGNPS) models to evaluate 20 management practices for sediment and P yields from 4 ha fields in a 1272 ha watershed of dairy farms. Five crop sequences [continuous corn (Zea mays L.) CC(OA)AAA, CC(OA)AAAA, CCC(OA)AAA, and CCCAAA; 0, oat (Avena sativa L.); A, alfalfa (medicago sativa L.)] combined with either fall moldboard plowing (mFMP), chisel plow (mFCP), no‐till (mNT), or no‐till substituting anhydrous ammonia for manure (aNT), were imposed on a toposequence of three Alfisols. The normal sequence, 2 yr of corn, oat/alfalfa seeding, 3 yr of alfalfa with fall application of solid manure followed by moldboard plowing, CC(OA)AAA‐mFMP, served as reference. Scenarios were subjected to 42 yr of simulated local climate. Scenarios with 43% or less row crop and mNT on a 4% sloping soil reduced sediment yield from 24 to 47%, at edge of field, but increased total P yield from 158 to 338%, mostly as soluble P. The EPIC output parameters (soil loss ratio [C] for June, erodibility [K], Manning's n, and SCS curve number [CN]) served as inputs to the (AGNPS) model, a cell based single rainfall event model that simulates runoff, sediment, and P yields from a watershed. Crop sequences not exceeding 43% corn and mFCP or aNT reduced watershed sediment yield 13 to 41%, but increased total P yield by 44 to 113% as compared with CC(OA)AAA‐mFMP. Average annual costs were $11 ha−1 less for these sequences when compared with CC(OA)AAA‐mFMP.
Bioavailability of Copper, Manganese, and Zinc in Poultry Litter
Authors: van der Watt H. v. H. , Sumner M. E. , Cabrera M. L.
Published: July 2010

Poultry litter is a useful agricultural by‐product but its potential for environmental pollution requires clarification. A poultry litter from north Georgia containing 1196, 944, and 631 mg/kg Cu, Mn, and Zn respectively was used to study the bioavailability of these metals in a short‐term greenhouse pot experiment. Metal uptake from poultry litter applications equivalent to 0, 15, 30, and 60 Mg/ha were compared on pure quartz sand and Cecil (clayey, kaolinitic, thermic Typic Kanhapludult) and Lakeland (thermic, coated Typic Quartzipsamment) soils at soil pH regimes of ≈5 and 7. Sudax [Sorghum bicolor (L.) Moench)] was used as test crop for metal uptake from 1 kg of soil during a 21‐d growth period. For the litter treatments, the Cu, Mn, and Zn concentrations were in the ranges 5 to 15, 62 to 1933, and 19 to 55 mg/kg. The Cu and Zn plant concentrations were in the normal range, while toxic Mn concentrations (>400 mg/kg) were found only in the case of the more clayey Cecil soil where reducing conditions in the pots may have been responsible for excessive solubilization of Mn. Soil pH was important in determining both ammonium bicarbonate‐DTPA and 0.1 M NaNO3 extractable soil Cu, Mn, and Zn. Significant (P < 0.01) correlations were found between soil Cu, Mn, and Zn extracted by these extractants and plant uptake, while inclusion of soil pH improved the significance of the regressions. Analyses of field soils revealed the build‐up of possible toxic levels of Cu, Mn, and Zn in only one soil which had received 6 Mg/ha of poultry litter per annum for 16 yr.
Sequential Fractionation of Copper, Lead, Cadmium and Zinc in Soils from or near Doñana National Park
Authors: Ramos L. , Hernandez L. M. , Gonzalez M. J.
Published: July 2010

A knowledge of the total amount of trace metals is not enough to assess the environmental impact of polluted soils. For this reason, the determination of metal species in solution is important to evaluate their behavior in the environment and their mobilization capacity. Soils contaminated by Cu, Pb, Cd, and Zn found at Doñana National Park (Spain) were examined for total content. Sequential extraction schemes were used to determine the degree of pollution and to partition the trace elements in soils. The three areas studied (marshes, stabilized sand, and mine) have different contamination levels. The northern‐most marshes of Doñana National Park have the highest total levels of the four metals due to the influence of a mine located 40 km away. The stabilized sand was not polluted by the metals studied. The bioavailable fraction of Cd represents more than 50% of the total Cd found in soils, and this percentage is much greater than that of the other elements examined. Most of the Cu was present in the organic fraction, with only small amounts being associated with the crystalline Fe‐oxide fraction. Lead and Zn were associated mainly with the crystalline Fe‐oxide fraction, but the amount of Zn associated with the carbonates and amorphous Fe‐oxide fractions was also significant. The total amount of Cu, Pb, Cd, and Zn in the soils and their distribution in the five fractions depended on total metal contents, soil type, and soil properties (i.e., pH and percentage of sand, clay, organic matter, and carbonates). Mobility of soil metals were Cd > Zn > Pb > Cu.
Ultraviolet‐B Radiation and Ozone Effects on Growth, Yield, and Photosynthesis of Soybean
Authors: Miller J. E. , Booker F. L. , Fiscus E. L. , Heagle A. S. , Pursley W. A. , Vozzo S. F. , Heck W. W.
Published: July 2010

The projected increase in solar ultraviolet‐B (UV‐B) radiation due to depletion of stratospheric ozone (O3) has caused concern regarding possible UV‐B damage to crops. At the same time, tropospheric O3 is projected to remain at concentrations that are known to damage crops. Since these two stressors may co‐occur, experiments were performed to determine their separate and joint effects on crop growth, yield, and photosynthesis. Open‐top chambers, equipped with filtered UV‐B lamp systems, were used in 3 yr of field studies to treat soybean [Glycine max (L.) Merr.; ‘Coker 6955’, ‘Essex’, and ‘S 53‐34’] with supplemental UV‐B radiation and/or O3 from emergence through physiological maturity. Treatment levels of biologically effective UV‐B radiation (UV‐BBE) simulated the increase in ground level UV‐B for stratospheric O3 depletion up to 37% (approximately a doubling of ambient UV‐BBE). Ozone treatment concentrations ranged from 14 to 83 nL L−1 (seasonal mean 12 h d−1 concentrations). Ultraviolet‐B radiation did not affect soybean seed yield in any of the 3 yr of the study. In 1 yr, UV‐B affected pod and seed number and pod weight, but the treatment means were not consistently related to the UV‐B dose. No O3 × UV‐B interactions were found for any yield component at final harvest. Biweekly harvests of Essex during the growing season did not reveal any persistent effects of increased UV‐B radiation on growth. Net carbon exchange rate (NCER), stomatal conductance, and transpiration of Essex soybean leaves were not suppressed by supplemental UV‐B radiation. On the other hand, O3 treatment consistently induced visible injury, suppressed NCER and water use efficiency, accelerated reproductive development, and suppressed growth and yield. It is concluded that tropospheric O3 poses a greater threat to soybean production than projected levels of UV‐B radiation.
Potential for Bioremediation of High Nitrate Irrigation Water Via Denitrification
Authors: Weier K. L. , Doran J. W. , Mosier A. R. , Power J. F. , Peterson T. A.
Published: July 2010

Nitrogen fertilizer application to irrigated corn (Zea mays L.) can result in N leaching from the crop rooting zone into groundwater. Microbial denitrification, with ethanol as an energy source, was evaluated for prevention of groundwater contamination under irrigated corn in Nebraska where irrigation water NO−3‐N levels can exceed 30 mg L−1. A field study was conducted on a Hord silt loam (Pachic Haplustoll) in central Nebraska by installing plastic (PVC) cylinders (28.7‐cm diam. by 1.8 m long) in soil to a depth of 1.2 m and irrigating with 17.1 cm of water containing 30 mg L−1 isotopically enriched (76.6 atom% 15N) KNO3‐N equivalent to 51.8 kg N ha−1. Soil remediation treatment included addition of 10 mL ethanol (644 kg C ha−1) to three of six cylinders. Gas samples taken every 6 h for 4 d from the soil surface and soil profile indicated that ethanol addition stimulated microbial respiration and denitrification. Cumulative loss of gaseous N from the soil surface over this period was 12.7 kg N ha−1 or 24.5% of the added 15N‐NO3; an additional 27 kg N ha−1 NO3 was lost from the ethanol‐amended soil profile. In the laboratory, intact soil cores taken at five intervals to a 132‐cm soil depth adjacent to field cylinders were brought to 90% WFPS (water‐filled pore space) by applying treatments of ethanol (19.8 kg C ha−1) and NO−3 (0.88 kg NO−3‐N ha−1) and incubated at 25 °C, with 100 mL L−1 C2H2, for 7 d during which time headspace gas samples were analyzed for N2O and CO2. Soil respiration and denitrification increased with ethanol addition except in surface soil where C availability was not limiting. We conclude that ethanol addition to high NO−3 irrigation water may remediate groundwater NO−3 contamination.
Sugarcane Production Impact on Nitrogen and Phosphorus in Drainage Water from an Everglades Histosol
Authors: Coale F. J. , Izuno F. T. , Bottcher A. B.
Published: July 2010

The Everglades Agricultural Area (EAA) in southern Florida is a 280 000‐ha tract of land that has come under scrutiny by environmental, agricultural industry, and government water management groups that are concerned with the impact of nutrient‐enriched drainage water on the ecology of adjoining bodies of water and wetlands. Sugarcane (Saccharum sp.) is grown on 155 000 ha or 78% of the cultivated organic soils in the EAA. The objectives of this study were to determine the N and P concentrations and off‐field loads in drainage water from sugarcane and fallow fields. Sugarcane was planted in four of eight hydraulically independent and similar field plots. Four plots were maintained fallow. Drainage water volume, and total nitrogen (TN), total dissolved phosphorus (TDP), and total phosphorus (TP) concentrations were monitored during 12 drainage events during two crop seasons. For two drainage events, TN concentrations were higher in drainage water from fallow plots that in drainage water from sugarcane plots and it was speculated that crop uptake of mineralized soil N may have contributed to the reductions during these events. Analysis of the mean for the 12 drainage events indicated no overall differences in TN off‐field loads between sugarcane and fallow plots. Further, no significant differences were found in TDP or TP concentration in drainage water from sugarcane and fallow plots during any of the drainage events monitored. It was concluded that, due to the large quantity of soil N and P mineralized and due to crop N and P uptake, the impact of sugarcane production on drainage water N and P concentrations was minimal.
Frequency of MUG Negative Escherichia coli in Kentucky Groundwater Samples
Authors: Coyne Mark S. , Schuler Jan C.
Published: July 2010

MUG negative Escherichia coli are a small fraction (2.5%) of the total E. coli in Kentucky groundwater samples. It is unlikely that they alone will cause a significant potential to underestimate fecal contamination using MUG as the primary criterion for that assessment. An unresolved question is how effectively MUG‐based, defined‐substrate tests address false negative water samples containing MUG positive E. coli.
Impact of Long‐Term Land Application of Broiler Litter on Environmentally Related Soil Properties
Authors: Kingery W.L. , Wood C.W. , Delaney D.P. , Williams J.C. , Mullins G.L.
Published: July 2010

The largest portion of Alabama's rapidly growing poultry industry is geographically concentrated in the Sand Mountain region of northern Alabama. The result is that large amounts of waste are applied to relatively small areas of agricultural soils. A study was conducted to determine the effects of long‐term broiler waste (litter) application on environmentally related soil conditions in the region. The region has an average annual rainfall of 1325 mm, which is evenly distributed throughout the year, a thermic temperature regime, and soils in the region are of the Ultisol order. In each of four major broiler‐producing counties, three pairs of sites consisting of long‐term (15–28 yr) littered and nonlittered fields on matching soil series and maintained under perennial tall fescue (Festuca arundinacea Schreb.) were sampled. Soil cores were taken to 3 m or lithic contact and depth‐incremented samples (0–15, 15–30, and each subsequent 30‐cm interval) were analyzed for organic C, total N, NO3‐N, pH, electrical conductivity, and acid‐extractable P, K, Ca, Mg, Cu, and Zn. Litter application increased organic C and total N to depths of 15 and 30 cm, respectively, as compared with nonlittered soils, whereas pH was 0.5 units higher to a depth of 60 cm under littered soils. Significant accumulation of NO3‐N was found in littered soils to or near bedrock. Extractable P concentrations in littered soils were more than six times greater than in nonlittered soils to a depth of 60 cm. Elevated levels of extractable K, Ca, and Mg to depths greater than 60 cm also were found as a result of long‐term litter use. Extractable Cu and Zn had accumulated in littered soils to a depth of 45 cm. These findings indicate that long‐term land application of broiler litter, at present rates, has altered soil chemical conditions and has created a potential for adverse environmental impacts in the Sand Mountain region of Alabama.
Adsorption of Dissolved Organic Carbon Extracted from Sewage Sludge on Montmorillonite and Kaolinite in the Presence of Metal Ions
Authors: Baham John , Sposito Garrison
Published: July 2010

The adsorption of dissolved organic carbon extracted from sewage sludge (SSDOC) and its complexes with Cu, Pb, and Cd by montmorillonite and kaolinite was measured at 283, 298, and 308 K. Experiments were conducted at 2 g L−3 clay suspension concentration in an ionic background of 50 mM NaClO4. Sufficient metal ion concentrations were present to saturate the clays (92 and 5 cmol(c) kg−1 for montmorillonite and kaolinite, respectively). The pH value of the suspensions was adjusted to 5.5 prior to initiation of the adsorption experiments. Kinetic studies conducted under aseptic conditions indicated that within 2 h the adsorption of the SSDOC by the clays reached an equilibrium value. Adsorption of SSDOC was found to be reversible with respect to small changes in the concentration of the adsorbate thus meeting the criteria for thermodynamic equilibrium. Rapid adsorption of the SSDOC suggests that adsorption was restricted to the external surfaces of the layer silicates. Statistical analysis of the data showed that all of the isotherms were described by a linear isotherm model. The average isosteric heat of adsorption () was estimated to be 0 ± 2 kJ mol−1 SSDOC, within experimental error, for each of the clay‐metal combinations. The low values for suggests that adsorption of SSDOC by montmorillonite and kaolinite is the result of an increase in the configurational entropy of the clay‐metal‐SSDOC system. Pooled adsorption data across temperatures yielded a single regression line for each clay‐metal‐SSDOC system with the following order of slopes and calculated average free energy of adsorption (): Pb > Cu > Cd. The observed order of the values for follow the same trend for the formation constants of metal humic complexes. This observation suggests that the favorable increase in is the result of changes in the conformation of the SSDOC making adsorption more favorable. When the value for was computed on the basis of external clay surface area the differences between the two clays decreased markedly, suggesting that adsorption was restricted to the external surfaces of the minerals.
Long‐Term Development of Element Fluxes with Bulk Precipitation and Throughfall in Two German Forests
Authors: Matzner E. , Meiwes K. J.
Published: July 2010

Long‐term monitoring of element fluxes with bulk precipitation and throughfall in two forest ecosystems of the German Soiling area revealed substantial changes in the chemical climate of these ecosystems. From 1969 to 1990, fluxes of NO3 and NH3 in throughfall increased by 40 to 60%. In contrast, SO4, H+, and Ca fluxes decreased by 30 to 60%. The changes of the element fluxes correspond to the development of emission rates in Germany for dust, SO2, and NO2.
Nonisothermal Sorption Gaseous Exchange in a Synthetic Soil
Authors: Goldman S. , Minkin L.M.
Published: July 2010

Nonisothermal sorption on soil surfaces is involved in the exchange of gases between soils and the atmosphere. This process is considered in context of soil pore‐size distribution. We found that the gas flux caused by nonisothermal sorption can be significant and can exceed the gas fluxes induced by other physical mechanisms of soil‐atmosphere exchange. We investigated the influence of fluctuations of soil temperature on the amount of gas sorbed to soil. For a given soil mass and for a given primary atmospheric gas, the ratio between the moles of gas sorbed or desorbed on a soil surface due to one Kelvin change of soil temperature and the moles of gas initially adsorbed ranges from 0.016 to 0.054 K−1. This temperature dependence, in turn, leads to a significant change of gas concentration in porous media, especially for dry and fine‐structured soils and clays. Significant gas fluxes can result. For an upper soil layer with a specific surface area of 2 × 104 m2 kg−1, the CO2 flux induced by nonisothermal sorption equals 8.3 × 10−4 kg m−2 s−1 when the soil temperature changes 1 K h−1 . These sorption processes are considered for soils having different pore‐size distributions. In certain fine‐structured soils, the number of sorbed molecules in a given soil mass is similar to the number of nonsorbed (mobile) molecules in the porous volume, particularly for gases with enthalpy of adsorption greater than 20 000 J mol−1 K−1. A new type of function is offered for describing pore diameter distribution. This function can be fitted easily to experimental data for many types of soil matrices, and it is also convenient for statistical moment analysis. This concept has been applied to the matrices of Walla‐Walla (coarse, silty, mixed, mesic Typic Haploxerolls) and Bashaw soils (very fine, montmorillonitic, mesic Typic Pelloxererts) (Oregon).
Sulfate Sorption in Soils under Acid Deposition: Comparison of Two Modeling Approaches
Authors: Prenzel Jürgen
Published: July 2010

Soil acidification under the impact of acid deposition is often modeled by adsorption isotherms. The assumption of solubility equilibria for basic Al sulfates is an alternative modeling approach. Similarities and differences between both concepts are discussed. A simple solubility equilibrium model is defined and used to demonstrate that the second model can explain results that are well described by typical adsorption isotherms. The same model can also explain a pH dependency of adsorption isotherms that has been widely reported. In the application to assumed soil acidification scenarios, predictions are presented that could not be described by an adsorption isotherm approach.
Quartz Vein Impact on Hydraulic Conductivity and Solute Transport through Quartz‐Phyllite Saprolite
Authors: Williams J. P. , Vepraskas M. J. , Hoover M. T.
Published: July 2010

Saprolite cannot be used for on‐site wastewater disposal in North Carolina if it has quartz veins within 60 cm (2 ft) of the septic trench bottom, because it is believed such features could transmit raw sewage quickly to groundwater. A quartz phyllite saprolite was sampled to compare the saturated and unsaturated hydraulic conductivities between samples with and without quartz veins. The fine sandy loam saprolite had veins that were approximately 0.8 cm wide and comprised 0.2 cm2/cm2 of the sample's cross‐sectional area. The mean saturated hydraulic conductivity values of 32 undisturbed cores with veins and 27 cores without veins were not significantly different (α = 0.10) and the geometric mean for a combined population was 0.85 cm/h. Unsaturated hydraulic conductivities for a soil water pressure head of −30 cm were also not significantly different between the two populations. Dye studies confirmed that water flowed both along the vein but also through the saprolite matrix. Examination of thin sections showed that pores within the vein were coated or plugged with Fe‐Mn oxides that restricted the water movement through the vein. It was computed that a noninteracting solute would travel 60 cm in the vertical direction in 33 h when the saprolite was saturated, and in 88 h when the soil water pressure head was −30 cm. These results suggested the quartz vein would not transmit raw sewage fast enough to contaminate groundwater at the site.
Iron Nutrition Influence on Cadmium Accumulation by Arabidopsis thaliana (L.) Heynh.
Authors: Rodecap Kent D. , Tingey David T. , Lee E. Henry
Published: July 2010

Greenhouse experiments were conducted to determine whether Arabidopsis thaliana (L.) Heynh., a putative Fe‐efficient species, accumulated higher concentrations of Cd from a sparingly soluble Cd source (cadmium dihydrogen phosphate) when growing in Fe‐deficient rather than in Fe‐sufficient conditions. The Arabidopsis plants, which were grown in double‐container, vermiculite‐hydroponic plot culture systems and were provided with nutrient solution containing either sufficient (89.5 µM) or deficient (0 µM) Fe supplied as the diethylene triamine pentacetate chelate, were exposed to four levels of Cd (nominally 0, 0.45, 0.89, or 1.78 mmol kg−1 vermiculite). At each substrate Cd level, rosette Cd concentrations were similar at both Fe levels, but racemes and seeds from the Fe‐deficient treatment accumulated significantly higher concentrations of Cd than those from the Fe‐sufficient treatment. For example, at the highest substrate Cd concentration, the Cd bioaccumulation factor (tissue Cd concentration predicted from polynomial response surface equations describing the relationship between tissue and substrate Cd concentrations divided by nominal substrate Cd concentration) for rosettes was 3.2 in both Fe treatments, but raceme Cd bioaccumulation factors were 1.7 and 0.9, and seed Cd bioaccumulation factors were 0.4 and 0.2 in the Fe‐deficient and Fe‐sufficient treatments, respectively. Rosette biomass was largely unaffected by tissue Cd level, but at tissue Cd concentrations of at least 1.26 mmol kg−1 for racemes and 0.32 mmol kg−1 for seeds, substantial biomass reductions occurred. Analysis of the uptake of other elements by Arabidopsis suggests that the greater accumulation of Cd by plants in the Fe‐deficient treatment may be a consequence of the species' Fe efficiency mechanisms. Our results support the hypothesis that uptake of toxic elements by Fe‐efficient species can be enhanced when the plants are growing in Fe‐deficient soils.