bluuebunny/crossref_metadata_2025 huggingface dataset:
Leaching of Atrazine in the Root Zone of an Alluvial Soil in Nebraska
Authors: Wehtje G. , Mielke L. N. , Leavitt J. R. C. , Schepers J. S.
Published: July 2010

Leaching of atrazine [2‐chloro‐4‐(ethylamino)‐6 (isopropylamino‐s‐triazine] was measured from the soil surface to below the root zone in an irrigated field under continuous corn (Zea mays L.). The field was located in the Platte River Valley of central Nebraska in the central Great Plains area of the USA. This nearly level site is typical of the Platte River Valley with a coarse‐ to medium‐textured soil of alluvial origin that contains low levels of organic matter, and with a water table at a 5‐m depth. Vacuum soil water extractors located 1.5 m below the soil surface recovered an average of 0.072% of the atrazine applied to the surface during 1979 and 1980. Analysis of groundwater recovered from wells on opposite ends of the experimental field indicated enrichment with atrazine in the direction of the hydraulic gradient. Results support direct downward leaching as largely responsible for the low‐level atrazine contamination detected in groundwater throughout the irrigated corn production areas of the valley.
Atrazine Dissipation in Conventional‐Till and No‐Till Sorghum
Authors: Ghadiri Hossein , Shea Patrick J. , Wicks Gail A. , Haderlie Lloyd C.
Published: July 2010

Atrazine (2‐chloro‐4‐ethylamino‐6‐isopropyl amino‐s‐triazine) dissipation was compared in conventional‐till and no‐till Holdredge loam soil (fine‐silty, mixed, mesic Typic Argiustolls) during the sorghum phase of a 3‐yr winter wheat (Triticum aestivum L.)‐sorghum [Sorghum bicolor (L.) Moench]‐fallow rotation. Dissipation was similar in both tillage treatments and the half‐life of atrazine in the surface 10 cm of soil was estimated by linear regression to be approximately 42 and 50 d in conventional‐till and no‐till plots, respectively. Movement of the herbicide below the upper 10 cm of soil was not significant during the 105‐d sampling period and only traces of atrazine (< 0.05 mg/kg) were found at the 40‐cm depth. Rectangular hyperbola equations were fit to quantitative data and could be used to estimate atrazine levels in the soil profile. Laboratory incubation suggested nonbiological hydrolysis to be the primary means of degradation. Similar atrazine dissipation in conventional‐till and no‐till plots was attributed to the relatively uniform acidity of the soil, which catalyzed atrazine hydrolysis. Long‐term application of NH4NO3 to all plots may have contributed to surface soil acidity and minimized the effect of tillage on atrazine dissipation.
Extractability and Plant Uptake of Trace Elements from Drilling Fluids
Authors: Nelson Darrell W. , Liu Shyilon L. , Sommers Lee E.
Published: July 2010

Land disposal of drilling fluids is a common practice following completion of an oil or gas well. Drilling fluids are formulated from components containing a variety of trace elements, but little is known about the bioavailability of these elements following application to soil. A greenhouse study was conducted to determine the yield and trace element content of Swiss chard (Beta vulgaris L.) and ryegrass (Lolium perenne L.) grown in two soils containing 0, 200, or 500 g kg−1 of three water‐based drilling fluids. The drilling fluids differed only in the source of barite (density regulating component). The barites used varied in trace element content. Addition of all drilling fluids increased soil pH, electrical conductivity of saturation extracts (ECsat), and concentrations of total and extractable trace elements. Growth of chard was only depressed by amending soil with the drilling fluid containing high levels of trace elements, while ryegrass growth was reduced with the 500 g kg−1 application rate of all drilling fluids and the 200 g kg−1 application rate of the drilling fluid with high levels of trace elements. Soil analyses suggested that chard and ryegrass yields were likely reduced by high Zn and ECsat, respectively, in drilling fluid‐treated soils. The concentrations of Zn, Cu, Cd, Pb, and As in chard and ryegrass tissues were directly related to total, DTPA‐extractable, and acetic acid‐soluble forms of these elements in soil. The application to soils of drilling fluids prepared from barite containing low concentrations of trace elements resulted in lower levels of trace elements in plant tissues than was obtained with control soils, because drilling fluid additions, increased soil pH and, thereby, decreased metal availability. Similar concentrations of Ba, Hg, and Cr were found in plant tissues grown in control soils and soil‐drilling fluid mixtures. This finding suggests that Ba, Hg, and Cr in drilling fluids are not plant‐available. Trace element availability to plants was similar for the three types of barites studied. Thus, the concentration in plants was a direct function of the amount of trace elements added to soil in the drilling fluids.
The Impact of Nitrification on Soil Acidification and Cation Leaching in a Red Alder Ecosystem
Authors: Van Miegroet H. , Cole D. W.
Published: July 2010

The objectives of this study were to investigate the impacts of internal nitrification on soil and soil solution acidity and on the rate of nutrient export through NO3− mediated leaching. This was achieved by comparing soil chemical properties and soil solution composition within a naturally N‐rich red alder (Alnus rubra Bong.) ecosystem to those of an adjacent Douglas‐fir [Pseudotsuga menziesil (Mirbel) Franco] forest where soil N levels were significantly lower and no measurable HNO3 production could be observed. In the red alder system, where > 100 kg ha−1 yr−1 of N were added through symbiotic N2 fixation, the net annual NO3− leaching past the 40‐cm soil depth amounted to 3460 mol charges ha−1, and NO3− concentrations in the solutions collected below 40 cm periodically exceeded drinking water standards of 10 mg L−1. The H+ and NO3− release was most pronounced in the forest floor and top 10 cm of the soil under alder occupancy and caused significant acidification of percolating solutions. Less than 1% of the total H+ input from internal (nitrification) and external (atmospheric) sources leached below the 40‐cm depth, which was indicative for the strong buffering capacity of this particular soil. The cation displacement reactions involved in this pH buffering caused a 15% decline in base saturation and a significant acidification of the upper part of the soil profile. The presence of large amounts of mobile NO3− in solution triggered accelerated cation leaching, causing a selective redistribution of primarily exchangeable Ca2+ from the A to the B horizon. These field studies lead us to conclude that the rate and the selectivity of NO3− mediated leaching in a red alder system could significantly lower the exchangeable cation pool in the rooting zone or cause nutrient imbalance, if a site is managed for repeated rotations of red alder.
Availability of Nitrogen in Municipal, Industrial, and Animal Wastes
Authors: King Larry D.
Published: July 2010

Nitrogen availability in soil amendments is important from both a crop production and an environmental protection standpoint. Municipal, industrial, and animal wastes were incubated with soil for 16 weeks and then NH4+‐N + NO3−‐N determined. Some of the wastes with high C/N ratios received supplemental inorganic N prior to incubation. Available N was generally greater from aerobically digested municipal sewage sludges than from anaerobically digested ones. However, variation within each sludge type was large and using an average value could lead to large errors in application rates. Availability of N in industrial wastes ranged from immobilization with paper mill sludges to 520 g kg−1 of the organic N in sludge from a poultry processing plant. A regression model, significant at the 0.001% level, predicted availability of N in aerobic and anaerobic municipal sludges within ± 30% of actual values [(g available N)/(kg organic N) = 380 + 135 (g organic N)/(kg waste) − 128(g total N)/(kg waste) + 1020(g C/g organic N) − 1120(g C/g total N), R2 = 0.89]. The model was not effective with data from other studies with different soils and sludges. The quantity of supplemental inorganic N immobilized by wastes having high C/N ratios increased with inorganic N added.
Effects of Saline‐Sodic Soil Chemistry on Soybean Mineral Composition and Stomatal Resistance
Authors: Coale F. J. , Evangelou V. P. , Grove J. H.
Published: July 2010

Soybean [Glycine max (L.) Merr.] productivity is severely limited by saline‐sodic soil conditions that occur in isolated spots in the river bottoms of western Kentucky. Productivity of soybeans grown on a gradient of soils of increasing saline‐sodic character were studied in greenhouse experiments. Soils with electrical conductivity (EC) exceeding 3.20 dS m−1 would not support soybean growth. Soybean plants accumulated significant quantities of Na when soil solution sodium adsorption ratio (SAR) exceeded 6.4 and relative tissue Na accumulation was highly correlated with SAR. Estimates of potential productivity were made by stomatal diffusive resistance measurements at three vegetative growth stages. Potential productivity was severely limited under conditions of high soil salinity. In soils of lower EC (< ≈ 2 dS m−1), soybean performance was affected to a greater extent by changes in SAR than by changes in EC. Dry matter production decreased with increasing SAR under low EC soil conditions.

In a second experiment, saline‐sodic soil was amended with four rates of gypsum (CaSO4·2H2O), (0, 2.6, 6.0, and 12.9 g kg−1). Gypsum‐amended pots were leached until EC was < 3.0 dS m−1. Plant dry matter production was minimized with the 2.6 g kg−1 amendment, which also produced plants with significantly reduced and negligible Na contents. At early growth stages (V4 and V7), stomatal diffusive resistance of plants grown on the gypsum‐amended soils was not affected by increasing SAR. Diffusive resistance measurements of large vegetative plants (V10) increased significantly at low soil solution SAR. The addition of gypsum apparently reduced the detrimental effects of physical impedence to root development and function in the poorly structured soil as well as soil solution SAR. The improved physical structure of the gypsum‐amended soil could improve root development, function, and crop productivity.
Methane Emissions to the Atmosphere Through Aquatic Plants
Authors: Sebacher Daniel I. , Harriss Robert C. , Bartlett Karen B.
Published: July 2010

The movement of methane (CH4) from anaerobic sediments through the leaves, stems, and flowers of aquatic plants and into the atmosphere was found to provide a significant pathway for the emission of CH4 from the aquatic substrates of flooded wetlands. Methane concentrations well above the surrounding ambient air levels were found in the mesophyll of 16 varieties of aquatic plants and are attributed to transpiration, diffusion, and pressure‐induced flow of gaseous CH4 from the roots when they are embedded in CH4‐saturated anaerobic sediments. Methane emissions from the emergent parts of aquatic plants were measured using floating chamber techniques and by enclosing the plants in polyethylene bags of known volume. Concentration changes were monitored in the trapped air using syringes and gas chromatographic techniques. Vertical profiles of dissolved CH4 in sediment pore water surrounding the aquatic plants' rhizomes were obtained using an interstitial sampling technique. Methane emissions from the aquatic plants studied varied from 14.8 mg CH4 d−1 to levels too low to be detectable. Rooted and unrooted freshwater aquatic plants were studied as well as saltwater and brackish water plants. Included in the experiment is a detailed set of measurements on CH4 emissions from the common cattail (Typha latifolia). This paper illustrates that aquatic plants play an important gas exchange role in the C cycle between wetlands and the atmosphere.
Cotton Yield Responses to Ozone as Mediated by Soil Moisture and Evapotranspiration
Authors: Temple Patrick J. , Taylor O. Clifton , Benoit Lawrence F.
Published: July 2010

A 2‐yr field study was conducted to determine injury and yield responses of normally irrigated and water‐stressed cotton (Gossypium hirsutum L.) to a gradient of ozone (O3) concentrations. Cotton (cv. SJ‐2), grown in open‐top chambers in the Central Valley of California, was exposed to six O3 treatments ranging from charcoal‐filtered (CF) to ambient plus 0.10 µL L−1 O3 (1981) or twice ambient O3 concentrations (1982) for the growing seasons of 1981 and 1982. Half the plots were irrigated optimally and the other half were provided with 25% (1981) or 20% (1982) less irrigation water (water‐stressed treatment). During the typically hot, dry growing season of 1981, cotton yield in normally irrigated treatments was reduced 20% by ambient levels of O3 in nonfiltered chambers (NF) relative to CF controls. Doubling ambient O3 concentration reduced yield 45%. Water‐stressed plants showed almost no response to O3. In 1982, the weather was cooler and cloudier than normal and potential evapotranspiration during the growing season averaged 20% less and ambient O3 concentrations averaged 39% lower than in 1981. Under these conditions, cotton yields at both levels of soil moisture treatments responded similarly to O3. Yields in NF chambers were reduced 15% relative to CF chambers. Doubling ambient O3 concentrations reduced yields 65%. The greater relative response of cotton to O3 in 1982 may have resulted from the cooler, more humid growing conditions, which increased the susceptibility of cotton to O3.
Effect of Acid Precipitation on Soil Microbial Activity: I. Soil Core Studies
Authors: Bitton Gabriel , Boylan Rae Ann
Published: July 2010

A study using soil columns was undertaken to examine the effect of acid precipitation on selected microbial processes. Following short‐term (92 d) exposure of soil cores to acid rain at pH 3.7 and 3.0, no alteration in enzyme activities was observed. The effect on soil respiration was dependent on soil type. Dinitrogen fixation was reduced only in one of the soils by the rain of pH 3.0. Following long‐term (690 d) exposure to acid rain, alterations in enzyme activities and CO2 evolution were dependent on the soil type. No reduction in adenosine triphosphate (ATP) content or N2 fixation were observed.
Stream‐Watershed Relations in the Missouri Ozark Plateau Province
Authors: Smart Miles M. , Jones John R. , Sebaugh Jeanne L.
Published: July 2010

Water chemistry and algal chlorophyll values in Missouri Ozark streams were more strongly related to land‐use practices on the watershed than bedrock geology or soil association. In general, concentrations of nutrients, chlorophyll, and most major ions were lowest in streams draining forests, intermediate in streams draining pastures, and highest in streams draining urban areas. In streams draining both forest and pasture areas, there was an exponential increase in the concentration of total P, total N, NO3−‐N, Na+, Cl−, and suspended chlorophyll a with an increase in percent pasture area on the watershed. These relations help identify the relative importance of land use on water chemistry and algal chlorophyll values, explain differences among streams in the region and enable us to approximate the impact of forest‐pasture conversion on streams not yet affected.
Residual Phytotoxicity of Chlorsulfuron in Two Soils
Authors: Anderson R. L. , Barrett M. R.
Published: July 2010

Chlorsulfuron {2‐chloro‐N‐[(4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐yl) amino carbonyl] benzenesulfonamide} selectively controls broad‐leaf weeds in winter wheat (Triticum aestivum L.), but also is extremely persistent in soil, resulting in residual injury to succeeding crops that are susceptible to chlorsulfuron. To determine the factors affecting chlorsulfuron degradation, the effect of environmental variables and method of application on chlorsulfuron persistence was measured in a loam and sandy loam soil using a corn (Zea mays L.) root bioassay. Increasing soil temperature from 20 to 40°C decreased chlorsulfuron persistence, with significant differences in chlorsulfuron concentration occurring 31 d after application to the sandy loam soil. Soil water level affected chlorsulfuron persistence only in the loam soil, where increasing the soil water level decreased persistence. Adding wheat residue to the soils increased chlorsulfuron persistence in the sandy loam, but not in the loam soil. One possible explanation for this reduced degradation in the sandy loam was a shift in pH toward basicity, as the addition of 0.050 kg kg−1 wheat residue raised the pH from 6.1 to 7.2. In the loam soil, the wheat residue did not affect soil I~H. Chlorsulfuron persistence was affected by texture, with longer activity occurring in the loam soil in all studies. Incorporating chlorsulfuron caused a greater loss of chlorsulfuron activity in the sandy loam, indicating that incorporation may influence chlorsulfuron persistence.
Adsorption‐Desorption Kinetics of Atrazine and Linuron in Freshwater‐Sediment Aqueous Slurries
Authors: Wauchope R. D. , Myers R. S.
Published: July 2010

A fast sampling and filtration technique was used to determine the rapidity with which the herbicides atrazine (2‐chloro‐4‐[ethylamino]‐6‐[isopropylamino]‐s‐triazine) and linuron (3‐[3,4‐dichlorophenyl]‐1‐methoxy‐1‐methylurea) are adsorbed or desorbed in sediment‐water mixtures. When aqueous solutions of the herbicides were exposed to wet sediment, or when wet sediments containing the adsorbed herbicides were exposed to water, the resulting adsorption or desorption, respectively, was initially very fast, approaching 75% of equilibrium values within 3 to 6 min. Herbicide adsorption on the sediments was completely reversible after 2 h of adsorption time: kinetic parameters obtained from a statistical fit of a sequential‐equilibria model to the adsorption data also fit desorption data. These results indicate that for these herbicides and similar nonionic solutes that have been in contact with sediment surfaces for ≤ 2 h, nonpoint pollution models for mixing streams may, to a first approximation, assume that adsorption‐desorption reequilibration is reversible and established rapidly relative to stream movement and sedimentation times.
Simulation Model for Soil Erosion‐Productivity Relationships
Authors: Shaffer Marvin J.
Published: July 2010

A mathematical model is described that simulates the impact of soil erosion on the short and long‐term productivity of soil. The model is known as the Nitrogen‐Tillage‐Residue Management (NTRM) model and has capabilities at the research level to simulate complex interactions of a growing crop such as corn (Zea mays L.) with climate inputs together with physical, chemical, and biological properties of the soil. Nitrogen‐Tillage‐Residue Management is intended to provide a means of evaluating existing and proposed soil management practices in the subject areas of erosion, soil fertility, tillage, crop residues, and irrigation. Illustration of model output, validation, and application is provided for three soils in the northern Corn Belt. These include a Fayette silt loam (Typic Hapludalf) (deep loess), a Dubuque silt loam (Typic Hapludalf) (shallow to bedrock), and a Dakota fine sandy loam (Typic Argiudoll) (shallow to coarse material). Corn growth and yield are simulated under noneroded and two levels of eroded conditions for a period of 100 yr. Management techniques, which include supplemental N, conservation tillage, and irrigation, are simulated on the eroded profiles to evaluate relative benefits and demonstrate the types of results produced by model sensitivity analyses.
Water Quality from Erosion Control Structures in Nebraska
Authors: Schepers J. S. , Francis D. D. , Mielke L. N.
Published: July 2010

Runoff collected from terrace and sediment‐control basins having tile‐outlet systems was compared with runoff water quality from Maple Creek in northeastern Nebraska. This study was part of a Model Implementation Project (MIP) initiated in 1978 to accelerate land treatment for erosion control and development of best management practices (BMPs). Soils in the area are very erosive (Nora‐Crofton complex) when subjected to high‐intensity rainfall in the spring and summer. Sediment concentrations in runoff from the terraces and sediment basins were initially high and comparable to stream concentrations until a pool of runoff water formed around the riser inlet of the tile discharge system. Formation of a pool allowed sediment to settle out away from the riser inlet, thus reducing sediment losses from the field. Sediment‐borne N and P accounted for 85 to 98% of total N and P losses from the land. Because tile‐outlet terraces and sediment basins effectively reduced sediment and nutrient concentrations in runoff, they proved to be an effective BMP for use by producers.
Aflatoxin Contamination of Preharvest Corn in Georgia: A Six‐Year Study of Insect Damage and Visible Aspergillus flavus
Authors: Mc Millian W. W. , Wilson D. M. , Widstrom N. W.
Published: July 2010

Insect damage, Aspergillus flavus Link infection, and aflatoxin contamination are recurring problems in preharvest corn (Zea mays L.) in the Coastal Plain of Georgia. A 6‐yr study (1977–1982) over 46‐county area revealed that insect damage ranged from a mean of 1.7 cm per ear in 1979 to 4.0 cm per ear in 1977. The incidence of aflatoxin contamination in grain samples ranged from 57% in 1982 to 100% in 1980. The highest concentration of aflatoxin (4708 µg kg−1 was recorded in a feld sample collected in 1977. The action level set by the Food and Drug Administration for aflatoxin is 20 µg kg−1. Insect damage contributed significantly to enhanced A. flavus sporulation and aflatoxin contamination. Levels of aflatoxin were positively correlated with temperature and total net evaporation. The occurrence of undamaged, uncontaminated corn in the Coastal Plain during a majority of the years suggests that crop management, including hybrid selection, planting date, and irrigation, may have a significant influence on the quantity of quality corn grain produced.
Fate of 2,4‐D Iso‐octyl Ester after Application to a Wheat Field
Authors: Grover R. , Shewchuk S. R. , Cessna A. J. , Smith A. E. , Hunter J. H.
Published: July 2010

Dissipation of iso‐octyl ester of 2,4‐dichlorophenoxyacetic acid (2,4‐D) and its acid metabolite in air, crop, and soil components were measured in a wheat (Triticum aestivum L.) field during and following application. Drift losses during application were only 0.2% of the amount applied. Air samples, collected at six heights ranging from 30 to 200 cm above the crop canopy during the first 7 d after application showed distinct ester gradients in the air, with concentration highest in the samples closest to the crop canopy. The highest concentration was measured during the afternoon of day 1 when 1604 ng m−3 were recorded 30 cm above the crop canopy. The vertical flux of the ester showed distinct diurnal variations with maxima reached in the early afternoon of day 1 and 2, followed by a rapid decline of the ester flux thereafter, corresponding with the depletion of the ester from the crop canopy. The total or cumulative vapor losses of the iso‐octyl ester over the 5‐d sampling period were estimated to be 93.5 g ha−1 or 20.8% of the amount applied.

The crop canopy intercepted 52% of the applied ester and acted as the major source of vapor losses. The magnitude of vapor activity was controlled primarily by the atmospheric stability and air temperature following application. On entry into the crop, the ester was hydrolyzed to the acid metabolite, which reached its maximum level on day 3. There appeared to be a rapid initial metabolism of the acid followed by a slow decline.

Ester losses from the soil surface occurred only when the soil surface was moist, i.e., after a rainfall event or in the early hours of the morning following the deposition of dew. In addition, both the hydrolysis of the ester and the subsequent degradation of its acid metabolite in the soil were dependent on the availability of surface soil moisture. No detectable 2,4‐D remained in the soil after 34 d.
Mobility and Persistence of Hexazinone in a Forest Watershed
Authors: Bouchard D. C. , Lavy T. L. , Lawson E. R.
Published: July 2010

The concentration of hexazinone [3‐cyclohexyl‐6‐(dimethylamino)‐1‐methyl‐1,3,5‐triazine‐2,4(1H,3H)‐dione] in soil, water, and plant tissue was monitored following hexazinone application (2.0 kg a.i./ha) to an 11.5‐ha watershed in northwestern Arkansas. The hexazinone concentration in the top 10 cm of soil on the watershed decreased to approximately 10% of the initial concentration in 42 d. Hexazinone dissipation rate on the watershed was more rapid than could be accounted for solely by degradation. Leaching of hexazinone to lower soil depths probably was important to hexazinone dissipation. Hexazinone degradation in soil incubated at 10 and 30°C followed first‐order kinetics and had a half‐life of 77 d at 30°C. Hexazinone was stable in incubated stream water requiring several years for 50% disappearance of the compound at 30°C. The maximum hexazinone concentration in the stream that drained the watershed was 14 µg/L, and hexazinone residues (< 3 µg/L) were detected in stream discharge over 1 yr after application. The amount of hexazinone transported from the watershed in stream discharge represented 2.0 to 3.0% of the amount of initially applied. Analyses of oak foliage and leaf litter collected from the forest floor indicated that < 0.10% of the hexazinone applied was returned to the forest floor in leaf deposition.
Nitrogen Fertilization and Ground Cover in a Hybrid Poplar Plantation: Effects on Nitrate Leaching
Authors: Mc Laughlin Richard A. , Pope Phillip E. , Hansen Edward A.
Published: July 2010

A 3‐yr study in northern Wisconsin measured the effects of ground cover treatments and N fertilization on tree growth, NO3−‐N leaching, and N mineralization in an irrigated hybrid poplar (Populus deltoides Bartr. × P. trichocarpa Torr. and Gray, clone NC‐9922) plantation. Annually fertilized (112 kg N/ha per year) and unfertilized plots were either maintained weed‐free (bare soil), allowed to revegetate with native weeds, or seeded to birdsfoot trefoil (Lotus corniculatus L.). Soil solution NO3−‐N was monitored in samples from permanently installed cup lysimeters. During the first two growing seasons, fertilization in bare soil plots increased NO3−‐N concentrations below the rooting zone to over 150 mg N/L. Tree growth response to fertilization in these plots occurred primarily in the third growing season, and NO3−‐N concentrations were much lower in and below the rooting zone relative to previous years. Fertilization increased NO3−‐N concentrations in the rooting zone during growing seasons two through four in trefoil plots and three and four in native weed plots. Nitrate‐N concentrations below the rooting zone in all trefoil and native weed plots averaged ≤ 11 mg/L until the end of the fourth growing season when it averaged 20 to 24 mg/L in fertilized plots. Fertilization significantly increased soil N mineralization in buried plastic bags only in plots with a ground cover and was 42 to 47% greater in these plots compared with fertilized bare soil plots. This study indicates that ground cover plays an important role in preventing leaching losses of fertilizer and native soil N in young biomass plantations.
Leaching of Nitrogen, Phosphorus, and Organic Carbon from Wheat Straw Residues: I. Rainfall Intensity
Authors: Schreiber J. D. , Mc Dowell L. L.
Published: July 2010

Knowledge of nutrients leached from crop residues will aid in understanding nutrient cycling in agricultural systems and in the development of small watershed chemical transport models. Using a multiple‐intensity rainfall simulator, wheat straw residue (Triticum aestivum L.) was subjected to 25.4 mm simulated rainfall at intensities of 7, 12, 25, 53, and 105 mm h−1. The wheat straw loading rate was 4500 kg ha−1. Runoff was sampled as a function of time and analyzed for PO43−‐P, NH4+‐N, NO3−‐N, and organic carbon (OC). Except for NO3−‐N, nutrient concentrations and losses were greater at the lower rainfall intensities. At each intensity, PO43−‐P, NH4+‐N, and OC concentrations in runoff from the wheat straw increased rapidly to maximum values and then decreased with time. After maximum nutrient concentrations were reached, a power function, Y = aXb, best described the relationship of nutrient concentrations with time, whereas a hyperbolic equation of the form Y = 1/(a + bX) best described the relationship of nutrient concentrations with runoff. The quantity (kg ha−1) of nutrients leached from the wheat straw followed the order C > P > N as (NH4+‐N + NO3−‐N). Amounts of N as (NH4+‐N + NO3−‐N) and C leached from the wheat straw were ≤ 1% of the nutrient content compared with 80 to 140 g kg−1 for P. This study also indicates that the variability in both the leachability and nutrient content of crop residues from different sources will be important, factors in the development of crop residue leaching models.
Leaching of Nitrogen, Phosphorus, and Organic Carbon From Wheat Straw Residues: II. Loading Rate
Authors: Schreiber J. D.
Published: July 2010

Using a rainfall simulator, wheat straw residue (Triticum aestivum L.) in 1.0‐m2 pans was subjected to simulated rainfall. Runoff from the wheat residue was sampled as a function of time and analyzed for PO43−‐P, NH4+‐N, NO3−‐N, and organic carbon (OC). Rainfall at 25 mm h−1 was applied for 1 h to five residue weights equivalent to field loading rates of 2200, 4500, 6700, 9000, and 11 200 kg ha−1. As loading rates increased from 2200 to 9000 kg ha−1, both concentrations and losses of PO43−‐P, NH43−‐N, and OC increased, whereas those of NO3−‐N decreased. During individual runoff events at all loading rates, PO43−‐P, NH4+‐N, and OC concentrations increased relatively rapidly to a maximum concentration in runoff and then decreased during the remainder of the 1‐h runoff event. The relationship of nutrient concentrations with time were described by a power function Y = aXb and to runoff by a hyperbolic equation of the form Y = 1/(a + bX). The quantity (kg ha−1) of nutrients leached from the wheat residue followed the order C > P > N. For all loading rates, percentage N (NH4+‐N + NO3−‐N) and C leached from the wheat residue was < 10 g kg−1, compared with 240 to 430 g kg−1 for P.
Tree Ring Response of White Oak to Climate and Air Pollution near the Ohio River Valley
Authors: Mc Clenahen J. R. , Dochinger L. S.
Published: July 2010

White oak (Quercus alba L.) tree ring chronologies were compared among five sites representing an apparent gradient of industrial air pollution emitted from sources in a portion of the Ohio River Valley near the southern Ohio‐northern Kentucky border. Response functions relating standardized ring‐width indices with principal components of climate for sites nearest the industrial area exhibited a strong nonclimatic influence from 1930 to 1978, which did not appear at more remote sites or in the 30 yr before 1930. Response functions for the entire 1900–1978 period declined in reliability to predict indices from climate at sites near the pollution sources, as did the response function derived for the most remote site when used to predict indices at the other four sites. Evidence for nonclimatic influence on indices appeared at all sites between about 1950 and 1966. The altered patterns of tree ring response to climate add to a growing body of evidence for broad‐scale changes in tree growth in the Northeast that may be associated with air pollution.
Determining the Number and Size of Soil Aliquots for Assessing Particulate Contaminant Concentrations
Authors: Gilbert Richard O. , Doctor Pamela G.
Published: July 2010

In this paper the planning of radionuclide and other environmental contaminant studies is discussed. This discussion is based on a study of the relationship between soil aliquot size and the variability between aliquot 241Am concentrations. The study consisted of drawing multiple soil aliquots of size 1, 10, 25, 50, and 100 g from a large composite soil sample collected at a nuclear weapons testing area on the Nevada Text Site. These aliquots were then analyzed for 241Am. The between aliquot standard deviation (s) of the data increased ninefold as aliquot size declined from 100 to 1 g. This implies that about 70 times as many 1‐g aliquots than 100‐g aliquots would be needed to achieve the same precision in the estimated mean of a single field sample. The data suggest a linear relationship between logarithms of s and aliquot weight (w). This relationship is used to determine the optimum w and number, n, of aliquots per field sample that should be used. These results are also extended to a second contaminant (239,240Pu in this case) that is in a ratio relationship to 241Am. Also, an approach is given for obtaining optimum numbers of field samples and number of aliquots per field sample to minimize either total sampling and analysis costs or the variance of the estimated mean. The aliquot data from the 241Am study indicate increasing median and geometric mean concentrations with increasing aliquot size. This happens because as aliquot weight increases there is a decrease in skewness of the frequency distribution of aliquot concentrations. Since the arithmetic mean is not affected (on the average) by a change in skewness, it may be preferred to the geometric mean or median when comparing results from studies that have used different aliquot sizes.
Biogeochemistry of Lead in McDonalds Branch Watershed, New Jersey Pine Barrens
Authors: Turner R. S. , Johnson A. H. , Wang D.
Published: July 2010

Lead concentrations, fluxes, and storage were measured in the vegetation, forest floor, and acid, sandy mineral soil (Quartzipsamments) of a forested watershed in the New Jersey Pine Barrens. Atmospherically deposited Pb at the McDonalds Branch Watershed was 140 g ha−1 yr−1 (8 µg L−1 in bulk precipitation) in 1980 to 1982, a substantial reduction from 350 g ha−1 yr−1 (17 µg L−1 in bulk precipitation) in 1978 to 1979. Virtually all Pb falling on the uplands was retained—75% by the organic forest floor and 25% by mineral soils, especially in B and C soil horizons. Total Pb content of the forest floor was 7.6 kg ha−1, with an accumulation rate of 100 g ha−1 yr−1 (1980–1982), or 1.3% of the forest floor pool. Estimated mean residence time of Pb in the forest floor was 220 yr. About 35 g Pb ha−1 yr−1 moved out of the forest floor in solution through the E horizon and was correlated strongly with dissolved organic matter. Approximately 30 g Pb ha−1 yr−1 accumulated in the B and C soil horizons. Less than 1 g Pb ha−1 yr−1 percolated past a depth of 2 m. Lowland muck soils and vegetation accumulated 98% of incoming Pb, with only 3.2 g Pb ha−1 yr−1 exported in the stream. Lead concentrations in the stream were correlated positively with dissolved organic matter and water level in the swamps. Lead in biota was contained mainly in the bark, fine roots, and foliage. Concentrations were: fine roots (18 mg kg−1) > bark (15 mg kg−1) > foliage (4 mg kg−1) > wood (0.5 mg kg−1). Although Pb concentrations in herbs, mosses, and lichens ranged from 10 to 60 mg kg−1, these plants accounted for very little biomass. Total Pb content of biota was 335 g ha−1, about 4% of the forest floor Pb content.
Biogeochemistry of Aluminum in McDonalds Branch Watershed, New Jersey Pine Barrens
Authors: Turner R. S. , Johnson A. H. , Wang D.
Published: July 2010

Aluminum concentrations, fluxes, and storage were measured in the vegetation, forest floor, and acid, sandy mineral soil of a forested watershed in the New Jersey Pine Barrens. Volume‐weighted mean Al concentrations in solution increased as water passed through the upland ecosystem, from 0.012 mg L−1 in bulk precipitation to 0.14 mg L−1 in throughfall to 0.45 mg L−1 in E horizon mineral soil, 0.60 mg L−1 in the B horizon, and 0.73 mg L−1 in the C horizon. Weighted mean Al concentration of the stream water was 0.15 mg L−1. Solution Al concentrations in different compartments of the ecosystem were related to the magnitude of moisture flux, dissolved organic carbon concentration, and pH. Soil solution and stream water Al concentrations were high in the winter and spring and low in the summer and fall, inversely following solution pH. Soil solution and stream pH were independent of precipitation pH because of internal control of H+ concentration by the soil and an apparent 0.5‐yr time lag in flushing of atmospherically deposited acids through the soil. Aluminum was partitioned strongly into the lower mineral soil horizons, but large stores of potentially labile Al were found in the upper mineral horizons and forest floor. Standing vegetation represented a relatively small pool of Al but cycled substantial amounts of Al between mineral soil and the forest floor.
Water Quality Effects of Clearcutting Upper Coastal Plain Loblolly Pine Plantations
Authors: Mc Clurkin D. C. , Duffy P. D. , Ursic S. J. , Nelson N. S.
Published: July 2010

The effect of clearcutting loblolly pine (Pinus taeda L.) on concentrations of sediment and nutrients in stormflows was studied on small catchments near Lexington, TN. The plantations were established on eroded and abandoned agricultural lands with fragile soils. Soil series on the catchments include Lexington silt loam (fine‐silty, mixed, thermic Typic Paleudalfs), Providence sill loam (fine‐silty, mixed, thermic Typic Fragiudalfs) and Ruston sandy loam (fine‐loamy, silicious, thermic Typic Paleudults). Eight catchments (0.17–0.56 ha) were instrumented with flumes equipped with water stage recorders to measure stormflow and Coshocton wheel samplers to obtain integrated samples of the flow. Plantations on four catchments were clearcut; the other four were left as uncut controls. Stormflow samples were analyzed for sediment‐phase total Kjeldahl nitrogen (TKN) and total phosphorus (TP) and solution‐phase TKN, TP, and potassium (K). Results indicated that a third or more of the TKN and two‐thirds of the TP exported in stormflow from the catchments was via sediment. Solution‐phase TKN and TP concentrations in stormflow were similar on clearcut and control catchments. Solution K concentrations were consistently higher from clearcut catchments. Rainfall inputs of TKN, TP, and K exceeded stormflow losses. The study demonstrated that pine plantations established on fragile soils can be clearcut without significant impact on water quality if recommended practices are used.
Reductive Dechlorination of the Pesticides 2,4‐D, 2,4,5‐T, and Pentachlorophenol in Anaerobic Sludges
Authors: Mikesell Mark D. , Boyd Stephen A.
Published: July 2010

The degradation of seven chlorinated aromatic compounds in anaerobic sewage sludge from three Michigan communities was examined. The compounds tested were 2,4‐D (2,4‐dichlorophenoxy acetic acid), 2,4,5‐T (2,4,5‐trichlorophenoxy acetic acid), PCP (pentachlorophenol), 2,4,6‐trichlorophenol, and 2‐, 3‐, and 4‐chlorophenol. All of the compounds tested were degraded in one or more of the sludges during a 70‐d incubation period. Overall, 4‐chlorophenol was the most persistent compound tested followed by 3‐chlorophenol. The most rapid degradative reactions were cleavage of the ether linkage of the phenoxy acetic acid herbicides 2,4‐D and 2,4,5‐T, and the removal of Cl atoms ortho to the phenolic OH group of the chlorophenols. The initial products of 2,4‐D and 2,4,5‐T degradation were 4‐chlorophenol and 2,4,5‐trichlorophenol. Reductive dechlorination of 2,4,5‐trichlorophenol (produced from 2,4,5‐T) gave 3,4‐dichlorophenol and 4‐chlorophenol which were the final products of 2,4,5‐T degradation. Dechlorination of PCP gave 3,4,5‐trichlorophenol as the initial transformation product, and further dechlorination gave 3,5‐dichlorophenol as the final product of PCP degradation. The Jackson sludge had the greatest capacity to degrade the compounds tested. With the exception of 3‐ and 4‐chlorophenol, all other compounds tested were completely degraded in 7 to 14 d in the Jackson sludge. Mason and Adrian sludges were similar in their degradative pathways overall, but significantly less active than the Jackson sludge.
Nutrient Returns from Field‐Drying of Logging Residue
Authors: Johnson James E. , Smith David W. , Stuart William B.
Published: July 2010

Increasing interest in utilizing logging residue for fuel has caused concern over additional nutrient removals from the site. On‐site drying of the residue may have an ameliorative effect due to nutrient returns during the drying process. To determine nutrient returns from field‐dried logging residue, four red maple (Acer rubrum L.) and chestnut oak (Quercus prinus L.) trees were felled and skidded into a 2‐ha clearcut area. Twig and leaf samples were collected immediately after cutting and after 2, 4, 8, and 16 weeks of field‐drying. Declines in both P and K concentrations in the leaves and twigs were noted over the drying period. When nutrient returns were computed on a kg ha−1 basis the following returns were observed after 16 weeks of drying: N, P, K, Ca, and Mg were 37, 2, 34, 20, and 2 kg ha−1, respectively. These amounts are similar to those cycled annually in litter‐fall in Appalachian mixed oak stands, which indicates that from a nutrient conservation standpoint, summer logging followed by field‐drying may be comparable to winter (leaf‐off) logging in these stands.
The Toxicity of Selected Organic Chemicals to the Earthworm Eisenia fetida
Authors: Neuhauser E. F. , Loehr R. C. , Malecki M. R. , Milligan D. L. , Durkin P. R.
Published: July 2010

A number of methods recently have been developed to biologically evaluate the impact of man's activities on soil ecosystems. Two test methods, the 2‐d contact test and the 14‐d artificial soil test, were used to evaluate the impact of six major classes of organic chemicals on the earthworm Eisenia fetida (Savigny). Of the organic chemicals tested, phenols and amines were the most toxic to the worms, followed in descending order of toxicity by the substituted aromatics, halogenated aliphatics, polycyclic aromatic hydrocarbons, and phthalates. No relationship was found between earthworm toxicity as determined by the contact test and rat, Rattus norvegicus Berkenhout and mouse, Mus musculus L. LD50 values. The physicochemical parameters of water solubility, vapor pressure, and octanol/water partition coefficient for the chemicals tested in the contact test did not show a significant relationship to the E. fetida LC50 values. These studies indicate that: (i) earthworms can be a suitable biomonitoring tool to assist in measuring the impact of organic chemicals in wastes added to soils and (ii) contact and artificial soil tests can be useful in measuring biological impacts.
Grouting as a Remedial Technique for Buried Low‐Level Radioactive Wastes
Authors: Spalding B. P. , Hyder L. K. , Munro I. L.
Published: July 2010

Seven grout formulations were tested in the laboratory for their ability to penetrate and to reduce the hydraulic conductivities of soils used as backfills for shallow land burial trenches. Soils from two sites, in Oak Ridge, TN, and Maxey Flats, KY, were used and both are classified as Typic Dystrochrepts. Three soluble grout formulations (sodium silicate, polypropenamide [polyacrylamide], and 1,3‐Benzenediol [resorcinol]‐formaldehyde) were able to both penetrate soil and sand columns and reduce hydraulic conductivities from initial values of ca. 10−4 m s−1 to < 10−8 m s−1. Three particulate grouts (lime [calcium oxide]‐fly ash, fly ash‐cement‐bentonite, and bentonite alone) could not penetrate columns; such formulations would, therefore, be difficult to inject into closed burial trenches. Field demonstrations with both sodium silicate and polyacrylamide showed that grout could be distributed throughout a burial trench and that waste‐backfill hydraulic conductivity could be reduced several orders of magnitude. Field grouting with polyacrylamide reduced the mean hydraulic conductivity of nine intratrench monitoring wells from 10−4 to 10−8 m s−1. Grouting of low‐level radioactive solid waste in situ, therefore, should be an effective technique to correct situations where leaching of buried wastes has or will result in groundwater contamination.
Estimating Algal Available Phosphorus in Suspended Sediments by Chemical Extraction
Authors: Dorich R. A. , Nelson D. W. , Sommers L. E.
Published: July 2010

The availability of sediment inorganic phosphorus (Pi) to algae was determined in 28 suspended stream sediments collected from an agricultural watershed in northeastern Indiana by short‐ (2‐d) and longerterm (14‐d) incubations. Unincubated sediment was also analyzed for dissolved molybdate reactive Pi (DMRP) and Pi extracted by: (i) sequential NaOH and HCl, (ii) sequential NH4F, NaOH, and HCl, (iii) nitrilotriacetic acid (NTA), (iv) hydroxy‐Al resin, and (v) total P. Available P (Paa) measured in sediments by 2‐d and 14‐d incubations with algae averaged 21 and 25% of total sediment P, respectively. Extraction of sediments with 0.1 M NaOH, 0.5 M NH4F, sequential 0.5 M NH4F + 0.1 M NaOH, NTA, and hydroxy‐Al resin removed an average of 36, 22, 31, 45, and 17% of the total P, respectively. Of the extractants tested, NaOH‐extractable Pi was significantly correlated with 2‐d and 14‐d Paa (r = 0.89*** and 0.95***, respectively) but NaOH extraction removed amounts of Pi that exceeded sediment Paa by a relatively constant amount. The results suggest that a single extraction with 0.1 M NaOH can be used to estimate both short‐ and longer‐term Paa in suspended stream sediments derived from noncalcareous soils in the Northcentral USA.
Formation of Secondary Minerals in Artificially Weathered Fly Ash
Authors: Warren C. J. , Dudas M. J.
Published: July 2010

A leaching experiment was designed to evaluate the chemical, mineralogical, and morphological nature of precipitation products formed during the accelerated laboratory weathering of an alkaline fly ash. The ash, classified as alkaline Modic, was leached with 0.005 mol L−1 H2SO4 in a series of five leaching columns for a period of approximately 90 d. The weathered residues were characterized by x‐ray diffraction, differential thermal analysis, infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. Three types of precipitation products were identified in the ash. Calcite formed through the dissolution of Ca from the ash and subsequent reaction with CO2 absorbed by the initial alkaline leaching solutions. Iron, dissolved from the ash under acidic conditions, precipitated as amorphous coatings on fly ash particles. Aluminum and Si dissolved from the glass of the ash was translocated and precipitated within alkaline environments as an amorphous aluminosilicate material best described as proto‐imogolite. Results indicated that the products of weathering of fly ash in terrestrial environments are similar to those documented for alkali soils and some soils of volcanic origin.
Nutrient Removal Potential of Selected Aquatic Macrophytes
Authors: Reddy K. R. , De Busk W. F.
Published: July 2010

The role of eight aquatic macrophytes in removing N and P from nutrient enriched waters was evaluated using microcosm retention ponds. The aquatic macrophytes included water hyacinth (Eichhornia crassipes), water lettuce (Pistia stratiotes), pennywort (Hydrocotyle umbellata), duckweeds (Lemna minor and Spirodela polyrhiza), azolla (Azolla caroliniana), salvinia (Salvinia rotundifolia), and a submersed macrophyte, egeria (Egeria densa). Nitrogen removal by aquatic macrophyte systems was in the order of water hyacinth > water lettuce > pennywort > Lemna > Salvinia > Spirodela > egeria during the summer season, while pennywort ranked first during the winter followed by water hyacinth, Lemna, water lettuce, Spirodela, Salvinia, and egeria. Phosphorus removal in summer was highest by water hyacinth and egeria systems, while pennywort and Lemna showed high P removal rates during the winter compared to other plants. Nitrogen and P removal were generally higher in summer than winter. Plant uptake accounted for 16 to 75% of total N removal, and 12 to 73% of total P removal, indicating the possibility of N and P removal by the mechanisms other than assimilation by plants.