bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selectivity and Soil Persistence of Certain Herbicides Used on Perennial Forage Grasses
Authors: Morrow L. A. , McCarty M. K. 
Published: July 2010

AbstractSeveral herbicides were applied in the field to the cool‐season grass smooth brome (Bromus inermis Leyss.) and to three warm‐season grasses, sideoats grama [Bouteloua curtipendula (Michx.) Torr.], switchgrass (Panicum virgatum L.) and indiangrass [Sorghastrum nutans (L.) Nash] to evaluate herbicide persistence in soils supporting each of these perennial forage grasses. Herbicides were applied once and the soil was sampled to a depth of 91 cm, 4 and 16 months after application. Bioassays, with soybeans [Glycine max (L.) Merr.] as the test crop, were conducted in the greenhouse to determine the location of the herbicides in the soil profile.Most herbicide residues 4 or 16 months after application were located in the 0‐ to 8‐cm soil depth. Only bromacil (5‐bromo‐3‐sec‐butyl‐6‐methyluracil), karbutilate [tert‐butylcarbamic acid ester with 3‐(m‐hydroxyphenyl)‐1,1‐dimethylurea] or terbacil (3‐tert‐butyl‐5‐chloro‐6‐methyluracil) at high rates depressed soybean growth in soil from the 8‐ to 15‐cm depth. Four months after herbicide application, a slight increase in soybean growth was evident in soil from the 15‐ to 30‐cm depth where bromacil, karbutilate, or terbacil had been applied to bromegrass.Germination of seed harvested from each grass was not affected by herbicide treatments.
Nitrification‐Denitrification Reactions in Flooded Soils and Water Bottoms: Dependence on Oxygen Supply and Ammonium Diffusion
Authors: Patrick W. H. , Reddy K. R. 
Published: July 2010

AbstractAmmonium nitrogen in a flooded soil or water bottom exposed to oxygen from the water column undergoes sequential nitrification and denitrification. Oxygen moving through the overlying water column causes the development of an aerobic surface layer of soil or sediment. Ammonium in this aerobic surface layer is nitrified and the resulting ammonium concentration gradient across the aerobic layer and the underlying anaerobic layer causes ammonium in the anaerobic layer to diffuse upward into the aerobic layer where it also undergoes nitrification. Nitrate produced in the aerobic layer then diffuses downward into the anaerobic layer where it is denitrified to N2 and N2O. Nitrate derived from ammonium nitrogen in the aerobic layer appears as an intermediate product in the nitrification‐denitrification reaction.A laboratory experiment utilizing 15N as a tracer showed that approximately one‐half of the nitrogen involved in the nitrification‐denitrification process was ammonium originally present in the surface aerobic soil or water bottom layer with the remainder diffusing up from the underlying anaerobic layer. Where oxygen was absent or limiting, nitrification either did not occur or occurred at a lower rate, resulting in a reduced amount of nitrate available for the denitrification process.
Distribution of Soil Fluorides Near an Airborne Fluoride Source
Authors: McClenahen James R. 
Published: July 2010

AbstractThe purpose of the study was to determine the effect of a major source of airborne fluorides on the geographical distribution of total fluoride in soils. Total fluoride determinations were made on soil samples collected from the same pastures at different distances from the source in spring and fall of 1973 and 1974. Samples were collected at depths of 0–5, 5–15, and 15–30 cm. Forage fluoride levels were used to determine areas of relatively high and low airborne fluoride impact, and soil sampling locations within these respective areas were segregated accordingly. Total soil fluoride increased with depth at low fluoride impact sites, but decreased with depth at high impact sites. This was a result of significantly (p = 0.05) elevated fluoride levels at the 0–5 cm depth on high impact sites compared to low impact areas. Total soil fluoride for all depths decreased with distance from the fluoride source, and approximated background levels at about 10 km. It is concluded that the observed magnitude of atmospheric fluoride contribution to total soil fluoride will probably have no significant impact on agriculture.
The Environmental Fate of Three Dichlorophenyl Nitrophenyl Ether Herbicides in a Rice Paddy Model Ecosystem
Authors: Lee An‐Horng , Lu Po‐Yung , Metcalf Robert L. , Hsu Err‐Lieh 
Published: July 2010

AbstractThe distribution and fate of three 14C radiolabeled diphenyl ether herbicides, nitrofen (2,4‐dichlorophenyl 4′‐nitrophenyl ether), X‐52 or methoxy‐nitrofen (2,4‐dichlorophenyl 3′‐methoxy‐4′‐nitrophenyl ether), and bifenox (2,4‐dichlorophenyl 3′‐carbomethoxy‐4′‐nitrophenyl ether), were evaluated in a laboratory rice (Oryza sativa L., Taichung Native No. 1) paddy model ecosystem. Nitrofen was relatively stable under model ecosystem conditions and was bioconcentrated and stored over a 33‐day period in tissues of alga (Oedogonium cardiacum Wittrock), snail (Physa sp.), mosquito (Culex pipiens quinquefasciatus Say), and fish (Gambusia affinis Baird & Girard). The carbomethoxy group of bifenox served as an effective degradophore and tissue storage of the parent compound was minimal. The methoxy group of the methoxynitrofen was not an effective degradophore. The laboratory rice paddy model ecosystem is a useful tool for evaluating the environmental effects and fate of pesticides to be used in rice culture.
Effect of Cacodylic Acid and MSMA on Nitrogen Transformations in Forest Floor and Soil
Authors: Bollen W. B. , Norris Logan A. , Stowers Kathleen L. 
Published: July 2010

AbstractCacodylic acid (hydroxydimethylarsine oxide) had no statistically significant effect on ammonification in three forest floors or three forest soils treated with 500 mg/kg peptone‐nitrogen, and up to 1,000 mg/kg arsenic as cacodylic acid. MSMA (monosodium methanearsonate) caused an increase in ammonification which was linear with the logarithm of the arsenic concentration. Decreased nitrification appeared to be related to the logarithm of increased arsenic concentration. The nitrification potential was low in test substrates; however, and the magnitude of the chemically induced depression of nitrification was small. The concentrations of arsenic which occur in forest floor and soil after precommercial thinning with MSMA and cacodylic acid should not have a significant adverse effect on nitrogen metabolism of forest floor and soil microorganisms.
Predicting Effects of Sulfuric Acid on Qualities of Irrigation and Drainage Waters in Calcareous Soils
Authors: Miyamoto S. 
Published: July 2010

AbstractConsiderable quantities of sulfuric acid (H2SO4) are being utilized in the southwestern United States for soil and water treatment. Future acid production may exceed demand and thus require disposal in some manner. Acid application or disposal to soils and water raises a question concerning effects on water quality. A numerical method is thus presented for predicting the effects of H2SO4 on qualities of irrigation and drainage waters, excluding trace elements, in calcareous systems. The method is based on known relations between ion equilibria and the solubility of calcite, magnesite, and gypsum. Computed results are presented for acid applied to waters or to soils under several hypothesized conditions, and compared with some reported laboratory or lysimeter data. Results indicate: (i) the numerical method is a promising tool, but requires further experimental verification; (ii) acid effects on water quality depend strongly on CO2 partial pressure and properties of soils and water, besides application rates; and (iii) the assumption that acid application produces equivalent amounts of soluble salts is an oversimplification.
Predicting Phosphate Movement through Soil Columns
Authors: Sawhney B. L. 
Published: July 2010

AbstractTo assess the potential pollution of ground water with P from septic tank drainfields, sorption capacities of various soils were determined over an extended period of time and related to P movement through soil columns using solutions having P concentrations similar to waste waters. The amounts of P sorbed by fine sandy loam (fsl) and silt loam (sil) soil columns before breakthrough curred were approximately equal to the sorption capacities determined from isotherms obtained over a sufficiently long reaction time of about 200 hours. In Merrimac fsl, breakthrough occurred after about 50 pore volumes of waste water had passed through the column while about 100 pore volumes passed through Buxton sil before the breakthrough occurred. Following breakthrough, concentration of P in the effluent continued to increase and approached the influent concentration after several hundred pore volumes of effluent had passed through the columns. The results, thus, suggest that while most deep soils should effectively remove P from waste water, ground water under drainfields installed in soils of low P sorption capacity after prolonged use may contain undesirably large concentrations of P.
Trifluralin Volatilization Losses from a Soybean Field
Authors: White A. W. , Harper L. A. , Leonard R. A. , Turnbull J. W. 
Published: July 2010

AbstractWe measured trifluralin (α,α,α‐trifluoro‐2,6‐dinitro‐N,N‐dipropyl‐p‐toluidine) concentrations in air and calculated volatilization losses from a 1.26‐ha field during application at soybean [Glycine max (L.) Merr.] planting and for 120 days after. Air samples, collected at three heights above the soil on 9 days during the season, showed that distinct trifluralin air concentration gradients existed throughout the study with concentrations highest closest to the ground. The highest concentration was measured during the application period (prior to soil herbicide incorporation) when a trifluralin level of 16,500 ng/m3 was recorded 20 cm above the ground. Generally, air concentrations were highest early in the season and decreased rapidly the first month. After herbicide incorporation, trifluralin air concentrations at 20 cm reached a maximum of 3,400 ng/m3 on day 2, and never exceeded 100 ng/m3 after day 35. Soil trifluralin levels at the 0.5‐cm depth decreased from 1.65 to about 0.3 µg/g on day 35 and to about 0.1 µg/g after 120 days.Seasonal trifluralin volatilization loss, excluding the application period, was estimated to be 22.4% of that applied with vapor losses during application amounting to 3.5% of the applied herbicide. Thus, total seasonal aerial losses were 25.9% of the originally applied herbicide. Of the total aerial losses, 13 and 15% were lost during application and through day 1, respectively. About half was lost during the first 9 days, and 90% in 35 days. Combined seasonal losses by other pathways (excluding volatilization) were almost 2.5 times greater than aerial losses.
Herbicides from Cropped Watersheds in Stream and Estuarine Sediments in Hawaii
Authors: Green R. E. , Goswami K. P. , Mukhtar M. , Young H. Y. 
Published: July 2010

AbstractAnalysis of sediments and soils associated with two estuaries on Oahu was conducted to determine if herbicides used in plantation crops reach coastal waters. Analytical procedures were developed for simultaneous extraction of atrazine (2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine), ametryn (2‐(ethylamino)‐4‐(isopropylamino)‐6‐(methylthio)‐s‐triazine), diuron (3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea), and DCA (3,4‐dichloroaniline). Field soil and runoff samples from two small monitored watersheds provided additional information on the dissipation of diuron in sugarcane (Saccharum officinarum) and pineapple (Ananas comosus) fields, and on diuron removal in runoff waters. Atrazine and ametryn dissipated rapidly in field soils, and neither was found normally in stream and estuarine sediments. Diuron, on the other hand, was sufficiently persistent in soils and sediments to be found in nearly all sediment samples obtained at 6‐month intervals at several sites for each estuary and its associated streams. Diuron in sediments was generally < 500 ppb (oven‐dry basis), but occasionally much higher concentrations were encountered at sites which were subject to localized contamination from spray equipment loading areas. Diuron appears to be transported in runoff waters principally in the solution phase rather than adsorbed on suspended solids. Estuarine waters (West Loch) contained 0.1 to 1 ppb diuron, while concentrations in runoff waters were several times higher. It is not known if these chronic low levels adversely affect the ecological balance of the estuary.
Characterization of an Agent in Aqueous Extracts of Beef Cattle Manure that Inhibits the Germination of Barley Seeds
Authors: Bell R. G. 
Published: July 2010

AbstractAqueous extracts of fresh beef cattle manure and of manure from the surface of a feedlot inhibited the germination of Galt barley (Hordeum vulgare L.) seeds in petri dish germination trials. Neither the polysaccharide nor protein fractions of fresh manure extract inhibited germination. Germination was inhibited similarly by a 1,000‐ppm solution of bile salts or by fresh manure extract. It is concluded that the major toxic principle in aqueous manure extracts that inhibits the germination of barley seeds consists of bile salts at concentrations in excess of 200 ppm.
Compounds of Zinc and Copper in Sewage Sludge Determined by Electron Spectroscopy
Authors: Cothern C. R. , Grote R. F. , Moddeman W. E. , Ritter C. J. , Zamierowski E. E. 
Published: July 2010

AbstractElectron Spectroscopy for Chemical Analysis (ESCA) was used to provide information concerning the chemical bonding of zinc and copper present in the sludge obtained from the Dayton, Ohio sewage treatment plant. The binding energy of the Zn 2p3/2 electron in sludge when placed under a vacuum of 10−7 Torr was 1023.8 ± 0.2 eV and the binding energy of the Cu 2p3/2 electron in the sludge under similar conditions was 937.2 ± 0.3 eV. These energies are characteristic of both Zn and Cu being in the positive two oxidation state. The electronegativity of the ligand attached to either of these metals was found to be 3.5 ± 0.1 on the Pauling scale. This indicates that Zn and Cu exist in similar compounds, that the ligand binding site is oxygen, and that the possible compounds include carbonate, carboxylate, phosphate, nitrate, silicate, and/or oxide. ESCA, when used in conjunction with other methods, offers excellent potential for more specifically identifying the chemical form of metal in sludge or sludge mixtures.
Changes in Inorganic Nitrogenous Compounds from Septic Tank Effluent in a Soil with a Fluctuating Water Table
Authors: Reneau R. B. 
Published: July 2010

AbstractChanges in NH4+, NO2−, and NO3− were monitored in situ during 1972, 1973, 1974, and 1975 in a Virginia Coastal Plain soil with a fluctuating water table. Samples of soil solution above and in a very slowly permeable plinthic horizon were analyzed for the above‐mentioned inorganic N fractions. Ammonium‐N in solution above the plinthic horizon decreased with increased distance from the drainfield in the direction of ground water flow. This decrease ranged from 23 to 4 µg/ml at 0.15 and 12.0 m from the drainfield, respectively. Decreased NH4+ was attributed to the processes of adsorption and nitrification. Nitrite and NO3− concentrations did not change significantly with distance above the plinthic horizon, but did accumulate in the plinthic material beginning at a 1.27‐m distance from the drainfield. Nitrification adjacent to the drainfield was possibly inhibited by the high oxygen demand, high NH4+ content, and general anaerobic conditions present. Nitrification above the plinthic horizon was apparently related to distance from the drainfield and fluctuations in the water table level. In this zone nitrification appeared to be followed by denitrification when NO3− moved into a more anaerobic zone or when higher water table levels resulted in inundation of the original zone of nitrification. Areas where denitrification was postulated to occur had redox potentials of approximately +200 mV (adjusted to 25C and pH 7.0). Nitrite and NO3− that moved into the plinthic horizon apparently did not undergo denitrification since conditions in this horizon are unfavorable for the biological denitrification process.
Effect of Selective Dissolution, Electrolytes, Aeration, and Sterilization on Technetium‐99 Sorption by Soils
Authors: Landa Edward R. , Thorvig Lisa (Hart) , Gast Robert G. 
Published: July 2010

AbstractThe objective of this study was to determine the extent that technetium‐99, a long‐lived beta‐emitting radionuclide, might be sorbed from aqueous solution by 11 well‐characterized soils, and to elucidate the sorption mechanisms involved. About 98% of the added 99Tc was sorbed within a period of 2 to 5 weeks by 8 of the 11 soils. The slow kinetics observed and the removal of trace quantities of 99Tc from solution in the presence of large amounts of chloride and phosphate tend to rule out anion exchange as the sorption mechanism. The lack of sorption exhibited by the low organic matter soils, the reduction in sorption following H2O2 digestion of the soil, and the high recoveries of sorbed 99Tc on extraction with NaOH suggest a role for the living and/or nonliving organic fraction of the soil. Sterilization of previously sorbing soils eliminated the sorption ability, indicating a microbial role in the process. Results of aeration experiments were ambiguous but suggest that anaerobic conditions are not a prerequisite for 99Tc sorption by soils.
Lead Distribution in the Cape Fear River Estuary
Authors: Baier Rodger W. 
Published: July 2010

AbstractWater and mud samples collected during 1973 and 1974 from the Cape Fear River, the region of its plume, and adjacent slope waters were analyzed for lead (Pb) by anodic stripping voltammetry and atomic absorption spectroscopy. Partitioning among adsorbed, strongly complexed, and electroactive states of Pb in seawater was estimated by filtration and voltammetric analyses at two pH levels.A significant fraction of the Pb present was found to be complexed in river water, but was dissociated upon mixing with shelf water. The concentration of Pb in offshore sediment decreased with increasing grain size. All concentrations of Pb found in the Cape Fear River estuary were well below recognized lethal values for aquatic life.
Effect of Redox Potential and pH on the Uptake of Cadmium and Lead by Rice Plants
Authors: Reddy C. N. , Patrick W. H. 
Published: July 2010

AbstractRedox potential and pH are two of the major factors influencing the mobilization and immobilization of heavy metals in flooded soils and sediments, and their availability to plants. A system developed for growing plants in soil suspensions where redox potential and pH can be controlled was used to study the uptake of cadmium (Cd) and lead (Pb) by rice plants (Oryza sativa L.). Uptake of Cd and Pb by root and shoot tissue, and their translocation from root to shoot, was determined at six different redox potentials (−200, −100, 0, +100, +200, and +400 mV) and four pH values (5, 6, 7, and 8). The effects of redox potential and pH on the levels of water‐soluble Cd and Pb in the soil suspensions were also studied. Almost all Cd entering the rice plants accumulated in the shoots. Total Cd uptake and shoot uptake increased with an increase in suspension redox potential and a decrease in pH. Water‐soluble Cd in the soil suspension was significantly correlated with total plant Cd and Cd uptake by shoot. Total Pb uptake, including Pb associated with the roots, decreased with an increase in suspension redox potential and pH. Uptake of Pb by shoot decreased with an increase in pH. No definite redox potential effect was found on Pb uptake by the shoot. Lead was less mobile than Cd in the rice plants and was primarily associated with the roots. Water‐soluble Pb decreased with an increase in redox potential and pH, and was significantly correlated with total plant Pb uptake and Pb uptake by shoot.
Physical Properties of Fly Ash‐Amended Soils
Authors: Chang A. C. , Lund L. J. , Page A. L. , Warneke J. E. 
Published: July 2010

AbstractFly ash from a coal‐fired power generating plant was mixed with five California soils at rates of 0, 2.5, 5.0, 10.0, 25.0, and 50.0% by volume. The physical properties related to the agronomic use of fly ash‐amended soils were characterized by determining water‐holding capacity, bulk density, hydraulic conductivity, and modulus of rupture on laboratory compacted soil cores. The moisture release characteristics of each mixture were also determined. Results indicated that a small amount of fly ash added to soils does appear to affect some measured physical properties of soils. At application rates > 25%, there was a consistent increase in water‐holding capacity (except a Domino loam soil), and a decrease in bulk density and modulus of rupture in all soils tested. The hydraulic conductivity increased with small amounts of fly ash, but declined rapidly as fly ash volume increased. Although fly ash application increased the water‐holding capacity of soils, the amount of water available to the plant did not change significantly. At a low applicant rate, fly ash amendment appeared useful in improving certain agronomic properties of soils.
Phosphate Removal from Sewage Water by Soil Columns
Authors: Lance J. C. 
Published: July 2010

AbstractPhosphate (PO4‐P) removal from secondary sewage effluent by calcareous sand columns was proportional to the infiltration rate. Phosphate concentrations in drainage from columns, packed with a mixture of sand from recharge basins and sand never previously exposed to sewage water, were below 1 ppm for over 200 days, increased, and finally leveled off at different concentrations, depending upon the infiltration rate. The equilibrium PO4‐P concentration could be increased or decreased by increasing or decreasing the infiltration rate. Evidently, PO4‐P was initially adsorbed by a reaction independent of flow velocity or retention time and, when this adsorption capacity was reached, PO4‐P was removed by a time‐dependent adsorption or precipitation reaction. The rapid response to either increases or decreases in infiltration rate suggested a precipitation reaction. The PO4‐P removal continued after application of 250 m of sewage water and 60,000 kg/ha PO4‐P during 7 years of flooding. Removal of 75–80% of the PO4‐P applied in secondary sewage effluent continued when the infiltration rate was maintained below 15 cm/day. Bermudagrass (Cynodon dactylon) greatly increased PO4‐P concentrations in column effluent samples.