bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bromide in the Natural Environment: Occurrence and Toxicity
Authors: Flury Markus , Papritz Andreas 
Published: July 2010

AbstractBromide ion is widely used as a tracer to study water and solute transport because it does not adsorb to negatively charged soil minerals. Therefore is moves approximately as fast as water in soil. This property and the small natural background concentration make Br− an ideal tracer. It is much better than Cl−, which behaves similarly, but which is ubiquitous in the environment. Since Cl− is a component of several fertilizers, it usually is found in agricultural soils in concentrations too high to allow its use. When using chemicals in the environment, one must consider their fate and toxicity. This review summarizes data on the occurrence of Br− in the environment and its toxicology. Since Br− has low toxicity in mammals, most freshwater organisms, and most plants, its use in small‐scale field studies should not endanger the biota. However, its application on a larger scale requires a careful evaluation of the concentration to be expected in ground and surface water. Based on the toxicity data, a quality criterion for groundwater of 1 mg Br− L−1 was established in the literature. To avoid the risk of chronic toxicity, the concentration of Br− water should not exceed the proposed criterion.
In Vitro Pollen Responses of Two Birch Species to Acidity and Temperature
Authors: Hughes R. N. , Cox R. M. 
Published: July 2010

AbstractPaper birch (Betula papyrifera Marsh.) and mountain paper birch (Betula cordifolia Regel) near the Bay of Fundy coast frequently intercept acidic advection marine fogs. Chemical deposition by these fogs is thought to be a factor contributing to the observed foliar browning symptoms associated with a marked deterioration of these trees in the area. In vitro experiments were performed to test whether pollen germination in these two birch species would be affected by acidity at levels routinely found in the fog. The combined effect of temperature with acidity was also examined. Pollen germination in both species was inhibited below pH 5.6 (P < 0.0001) and the effect of incubation temperature was also significant (P < 0.01) in both species. There was no difference in in vitro pollen germination between species (P > 0.05) in response to acidity, based on combined data from 12 trees of each; the optimum germination temperature was 22 °C for B. papyrifera and 21 °C for B. cordifolia.
Growth and Trace Element Concentrations of Five Plant Species Grown in a Highly Saline Soil
Authors: Retana J. , Parker D. R. , Amrhein C. , Page A. L. 
Published: July 2010

AbstractKesterson Reservoir and other impoundments in the San Joaquin Valley, California, have received large volumes of saline irrigation drainage water that is enriched with trace elements, including As, B, Mo, Se, U, and V. When these ponds are allowed to dry and revert to terrestrial ecosystems, careful soil water and vegetation management may be needed to prevent toxicological hazards to wildlife and/or livestock. We conducted a 248‐d column study in the greenhouse using a soil from Kesterson to assess the growth of salt‐ and B‐tolerant genotypes, and to determine the uptake of As, B, Mo, Se, U, and V by these genotypes. Electrical conductivity decreased with soil depth, from 14 to 5 dS m−1, with B, Mo, Se, and U concentrations paralleling the soil salinity, whereas As and V were higher in the subsoil. Three grasses, alkali sacaton [Sporobolus airoides (Torr.) Torr.], tall wheatgrass [Elytrigia pontica (Podp.) Holub], Indian ricegrass [Oryzopsis hymenoides (Roem & Schult.)], and two Se‐accumulators, Astragalus bisulcatus (Hook.) and A. racemosus Pursh., were successfully established after a preplanting leaching treatment to reduce salts in the seed zone. Three cuttings of alkali sacaton and tall wheatgrass resulted in total shoot yields of 11.1 and 7.6 g per column, respectively, but only 0.8 for a single cutting to the less salt‐ and B‐tolerant Indian ricegrass. The slower‐growing A. bisulcatus and A. racemosus yielded 3.8 and 4.4 g per column, respectively. Shoot concentrations of As, U, and V were low (<3 mg kg−1) in all genotypes, and do not seem to pose food‐chain transfer hazards at this site. Molybdenum and Se shoot concentrations of all genotypes exceeded the upper safe limits for consumption by ruminants, and shoot B concentrations were also high (>60 mg kg−1). Despite high soil solution SO4 concentrations, both Astragalus species accumulated Se to high concentrations in the shoots (ca. 650 mg kg−1), and shoot harvest removed the equivalent of 2 to 3.5 kg Se ha−1. Growth of these Se‐accumulating species shows promise as a means of direct removal of Se from Se‐contaminated sites and could become a component of effective remediation strategies.
Atrazine, Alachlor, and Metolachlor Mobility through Two Sandy Wisconsin Soils
Authors: Wietersen R. C. , Daniel T. C. , Fermanich K. J. , Girard B. D. , McSweeney K. , Lowery B. 
Published: July 2010

AbstractPesticide mobility through Sparta sand from the Lower Wisconsin River Valley (LWRV) and Plainfield sand from the Central Sands (CS) of Wisconsin was examined to interpret results from state‐sponsored groundwater monitoring programs and to identify fundamental mechanisms important in pesticide transport through the unsaturated zone. The mobility of 14C‐labeled atrazine [2‐chloro‐(4‐ethylamino)‐6‐(isopropylamino)‐s‐triazine], alachlor [2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxym ethyl) acetamide], and metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl) acetamide] was monitored through replicated intact soil column‐microlysimeters. Soil columns of Sparta sand (sandy, mixed, mesic Entic Hapludolls) from the LWRV and Plainfield sand (sandy, mixed, mesic Typic Udipsamments) from the CS were instrumented in the greenhouse to simulate field conditions. All pesticides were shown to be much more mobile through the Sparta sand as compared to Plainfield sand. Peak atrazine concentration was 15 times greater in the leachate from the Sparta soil than from the Plainfield sand. Percentage loss of applied pesticide was four times greater in the leachate from the Sparta soil than from the Plainfield sand. Similar results were found for metolachlor and alachlor. The relative order of mobility for each soil was found to be atrazine > metolachlor > alachlor. Factors found to contribute to increased mobility of pesticides through the Sparta sand include higher hydraulic conductivity, smaller water‐holding capacity, and less atrazine adsorption due to less organic C and clay content. The hydraulic conductivity (Ksat) of the upper motzone (0–20 cm) of the Sparta soil is five times faster than the Plainfield soil. The waterholding capacity and the atrazine adsorption coefficient (Kd) of the Plainfield sand were measured to be 1.6 and 1.8 times greater, respectively, than those of the Sparta soil.
Nitrate Movement after Anhydrous Ammonia Application in a Ridge Tillage System
Authors: Clay D. E. , Clay S. A. , Brix‐Davis K. , Scholes K. A. 
Published: July 2010

AbstractRidge application of N fertilizer has been promoted as a management tool to reduce nitrate movement. However, anhydrous ammonia applicator knives produce slots, which may impact water and nitrate movement. The objective of this study was to determine the effects of N fertilizer placement by an anhydrous ammonia applicator on nitrate movement within a ridge tillage system. Anhydrous ammonia was applied in a subsurface band to the ridge or valley areas of a ridge tillage system at the rates of 0 or 200 kg N ha−1. Rainfall (17 cm) was applied with a drop‐type artificial rainfall simulator 3, 10, and 24 d after fertilizer application in a fallowed field. Percolating water was collected in grid lysimeters (15 by 15 cm) located 75 cm below the soil surface of a Brandt silty clay loam (fine‐silty over sandy or sandy skeletal mixed Pachic Udic Haploboroll). Rainfall timing and N fertilizer placement influenced N fertilizer loss. The percentage of applied fertilizer collected in lysimeters when rainfall occurred 3 and 10 d after fertilizer application was 0 and 15%, respectively. When rainfall occurred 24 d after application, 49 and 73% of the applied N was leached through the profile from valley and ridge treatments, respectively. Increased N loss in the ridge treatment may have resulted from the fertilizer slot remaining open during the rainfall, while in the valley treatment the slot closed.
Estimation of Sorption Coefficients for Fungicides in Soil and Turfgrass Thatch
Authors: Dell C. J. , Throssell C. S. , Bischoff M. , Turco R. F. 
Published: July 2010

AbstractEnvironmental fates of turf‐applied fungicides are not well understood. The role of thatch as a sorptive surface for fungicides has not been evaluated. Thatch may decrease mobility of fungicides and decrease their potential to be transported off‐site. Batch type sorption studies were conducted to determine sorption coefficients (Kf) for the fungicides triadimefon, [1‐(4‐chlorophenoxy)‐3,3‐dimethyl 1‐1‐(1H‐1,2,4‐triazol‐1‐g‐1) butanone], vinclozolin [3‐(3,5‐dichlorophenyl)‐5‐methyl‐5‐vinyl‐1,3‐oxazolidine‐2,4‐dione], and chloroneb (1,4‐dichloro‐2,5‐dimethoxybenzone) in thatch and in the underlying soil. The Kf values also were derived from octanol/water partitioning coefficients (Kow) for these and five other compounds. All Kow values were determined with reverse‐phase high pressure liquid chromatography (HPLC) and calculated from physical properties of the fungicides. The Kf values [µmol(l‐n) Ln kg−1] determined from isotherm data for thatch and soil (respectively) were 90 and 10 for triadimefon, 163 and 21 for chloroneb, and 431 and 47 for vinclozolin. When Kf values were adjusted for organic C content of the sample, the resulting Kow values were similar for thatch and soil. The Koc values estimated from HPLC‐derived Kow values were consistently less than those obtained using batch isotherm methods. The Kow values calculated from physical properties of the fungicides were poorly correlated with measured values. The HPLC method appears to be useful for determining sorption coefficients. Results indicate that thatch substantially increases fungicide sorption, which, in turn, decreases the potential for these compounds to migrate off site.
Permethrin and Sulprofos Washoff from Cotton Plants as a Function of Time between Application and Initial Rainfall
Authors: Willis G. H. , McDowell L. L. , Smith S. , Southwick L. M. 
Published: July 2010

AbstractUnderstanding pesticide foliar washoff is important in environmental modeling, pest management, and development of integrated management systems. This study was conducted to determine the effect of elapsed time between spray application and initial rainfall on insecticide washoff from foliage. Permethrin [(3‐phenoxyphenyl)‐methyl(1K,S)‐cis,trans‐3‐(2,2‐dichloroethenyl)2,2‐dimethylcyclopropanecarboxylate] and sulprofos [O‐ethyl O‐(4‐methylthiophenyl)‐S‐propyl phosphorodithioate] were applied to mature cotton (Gossypium hirsutum L.) plants as tank‐mixed emulsifiable concentrates with a water carrier. Simulated rain (51 mm in 1 h) was applied to the cotton plants at different times after insecticide application to determine washoff characteristics for both compounds. Residues of both insecticides became increasingly resistant to washoff with increasing time interval between insecticide application and initial rainfall. The mean amounts of both insecticides washed from the plants were related to the mean insecticide loads on the plants and decreased with time. On the average, the first 2 to 3 mm of rain removed 50% of the total amounts of insecticide washed from the plants by the 51‐mm storm.
Use of Cellulosic Substrates for the Microbial Treatment of Acid Mine Drainage
Authors: Béchard Geneviève , Yamazaki Hiroshi , Gould W. Douglas , Bédard Pierre 
Published: July 2010

AbstractA mixed aerobic‐anaerobic microbial treatment process was developed previously for acid mine drainage (AMD) using straw as a substrate. The process was effective only if AMD was supplemented with sucrose. The present study was conducted to determine which, if any, of three cellulosic materials could sustain the microbial treatment of AMD without the addition of a sucrose amendment and to determine the effect of the retention time on the performance of the reactors. The performance of small reactors that treated simulated AMD in the continuous mode was evaluated using alfalfa (Medicago sativa L.) hay, timothy (Phleum pratense L.) hay, and straw with a 5‐d retention time. Parameters measured were pH, Fe, Al, sulfate, and ammonium. Timothy hay and straw sustained AMD mitigation for 3 wk, and thereafter all activity ceased. After the reactors ceased treating AMD, the mitigative activities were reinitiated by the addition of sucrose, but not by urea. Alfalfa sustained AMD mitigation for a longer time period than either straw or timothy. The effect of three retention times, 3.5, 7, and 35 d, was then investigated for reactors containing fresh alfalfa. Increasing the retention time resulted in better metal removal and a greater pH increase. With a 7‐d retention time, 75 L of simulated AMD were neutralized from a pH of 3.5 to a pH value greater than 6.5. Reactors operating with a 3.5‐d retention time treated only 58.3 L of simulated AMD before failing. Ammonium was detected in effluents of active reactors. The results of this study indicate that a low maintenance microbial treatment system can be developed with alfalfa as a substrate without the addition of a sucrose amendment.
Nutrient Leaching following Land Application of Aerobically Digested Municipal Sewage Sludge in a Northern Hardwood Forest
Authors: Medalie L. , Bowden W. B. , Smith C. T. 
Published: July 2010

AbstractConcentrations of selected cations and anions were determined in soil solutions from a forested site in southern New Hampshire during the first growing season after surface application of an aerobically‐digested, limed, liquid municipal sludge. Sludge was applied in June 1989 at 0, 3.3, 6.9, and 14.5 Mg ha−1, which corresponded to 199, 396, and 740 kg N ha−1 as total Kjeldahl N (TKN). Porous, suction‐cup lysimeters were used to sample soil solutions below the rooting zone (≈60cm) within subplots designed to include (untrenched) exclude (trenched) uptake by vegetation. Following sludge application, measured solute concentrations remained low until September 1989, when NO3, Cl, Ca, Mg, Na, and K in trenched subplots increased simultaneously to maximum values in October or November 1989, just before the soil froze for the winter. Nitrate was the dominant anion in soil solutions from trenched subplots and averaged in excess of 0.71 mmol L−1 (10 mg L−1 NO3‐N) at all loading rates. Highest concentrations of NO3 occurred on subplots with the highest sludge application rates. In the untrenched areas, NO3 concentrations rarely exceeded 0.001 mmol L−1; Cl increased in treated areas and was the dominant anion by the end of the season. Soil solution NH4, PO4, SO4, K, and pH did not change significantly for any sludge application rate. Comparison of results from trenched and untrenched areas suggests that, at application rates of up to 14.5 Mg ha−1 (799 kg TKN ha−1), a combination of physical, chemical, and biological factors (most likely plant uptake) limited the movement of sludge or sludge‐derived constituents from the sites of application.
Foliar Amino Acid Accumulation as an Indicator of Ecosystem Stress for First‐Year Sugar Maple Seedlings
Authors: McLaughlin James W. , Reed David D. , Bagley Susan T. , Jurgensen Martin F. , Mroz Glenn D. 
Published: July 2010

AbstractAccumulation of certain plant foliar amino acids (arginine, glutamine, and proline) can be used as indicators of anthropogenic and natural stressors, such as atmospheric deposition and mineral nutritional imbalances, which result in decreased plant growth. In this study a number of factors were evaluated to assess the use of foliar amino acid accumulation as indicators of sugar maple seedling stress at two sugar maple dominated forests in Michigan. These factors were: (i) first‐year sugar maple (Acer saccharum Marshall) seedling growth, (ii) N and P nutrition, (iii) soluble foliar and root total amino acid concentrations, and (iv) concentrations of foliar arginine, glutamine, and proline. The most southern site (Wellston), which was exposed to high atmospheric deposition and had high available soil P and seedling foliar P, had greater seedling growth. Foliar glutamine, arginine, and proline were greater at the most northern site (Alberta), which received lesser amounts of atmospheric deposition, but also had lower levels of available soil phosphorus, seedling foliar phosphorus, less seedling growth, and greater canopy closure. These results suggest that since atmospheric deposition is high in nitrogen, even the low levels of deposition at Alberta may be interacting with ecological variables such as, available soil phosphorus, light, or moisture to result in N/P imbalances and consequently higher arginine and glutamine concentrations in seedling foliage.
Analysis of Volatile‐Phase Transport in Soils Using Natural Radon Gas as a Tracer
Authors: Chen C. , Thomas D. M. 
Published: July 2010

AbstractWe have conducted a field study of soil gas transport processes using radon gas as a naturally occurring tracer. The experiment monitored soil gas radon activity, soil moisture, and soil temperature at depth; barometric pressure, rainfall, and wind speed were monitored at the soil surface. Linear and multiple regression analysis under natural environmental conditions are influenced by soil moisture content, barometric pressure variations, soil temperature, and soil structure. The effect of wind speed on subsurface radon activities under our field conditions has not been observed.
Nitrate Leaching in a Udic Haploboroll as Influenced by Fertilization and Legumes
Authors: Campbell C. A. , Lafond G. P. , Zentner R. P. , Jame Y. W. 
Published: July 2010

AbstractAn ongoing 34‐yr crop rotation experiment being conducted on a heavy clay at Indian Head, SK, allowed a snap‐shot assessment to be made of the influence of fertilization, legume green manure and legume‐grass hay crops, and frequency of cropping to monoculture hard red spring wheat (Triticum aestivum L.) on deep leaching of soil nitrate (NO3). The results showed that NO3 leaching was greatest when summer fallowing was most frequently employed. Although N fertilization may increase No3‐N leached, using a soil test as a guide to choosing fertilizer application rates and cropping annually will minimize NO3 leaching. Further, we found that, although deep‐rooted forage crops such as alfalfa (Medicago sativa L.) remove NO3 and water to a depth of 2.4 m, and because legumes increase the N supplying power of the soil, considerable NO3 leaching can still occur under these systems. This is especially true if legume plowdown is followed by a fallow period, because during the fallow period, copious net N mineralization may occur together with increased soil moisture storage. These results do not imply that NO3 leaching is pervasive on the Canadian Prairies, but they do confirm certain well‐known principles: viz., that NO3 leaching can be expected whenever conditions favor NO3 accumulation and water buildup in soil. Consequently, it is important to keep the land cropped for a large proportion of the time and to use fertilizers at moderate rates based on soil tests.
Hydraulic Conductivity of an Allophanic Andisol as Affected by Solution pH
Authors: Nakagawa T. , Ishiguro M. 
Published: July 2010

AbstractRecently, acid precipitation problems have become serious in many regions of the world. The adverse effects of acid precipitation on soils are also feared. In this study, our objective was to determine the effect of inflowing solution pH on saturated hydraulic conductivity (K). The K values were determined at a constant hydraulic gradient in columns packed at a dry bulk density of 0.51 Mg m−3. Influent solutions with the same electrolyte level (1 molc m−3) were prepared at pH 3, 4.2, 5.7, 10, and 11, respectively. The K values decreased when the influent solutions were pH 3 and 11. The K values at 38 pore volumes of an effluent decreased to ≈0.067 of the initial K0 at pH 3, and ≈0.25 of the initial K0 at pH 11, respectively. Measurements of dispersion by optical absorbance method were also carried out. Clay dispersed at low pH (pH < 4.5) and high pH (pH > 10). The structure of the soil columns when K was reduced were visually inspected after K measurements. Those aggregates at the upper portion (≈1 mm thickness) of the soil column seemed to be destroyed by dispersion of clay. It became clear that acidic or alkaline solution decreased permeability of the allophanic andisol. Such a reduction of permeability may significantly change the water balance in a field.
Phosphorus Nutrition of Arsenate‐Tolerant and Nontolerant Phenotypes of Velvetgrass
Authors: Meharg A. A. , Naylor J. , Macnair M. R. 
Published: July 2010

AbstractVelvetgrass (Holcus lanatus L.), also known as Yorkshire fog grass, has evolved tolerance to high levels of arsenate, and this adaptation involves reduced accumulation of arsenate through the suppression of the high affinity phosphate‐arsenate uptake system. To determine the role of P nutrition in arsenate tolerance, inhibition kinetics of arsenate influx by phosphate were determined. The concentration of inhibitor required to reduce maximum influx (Vmax) by 50%, K1, of phosphate inhibition of arsenate influx was 0.02 mol m−3 in both tolerant and nontolerant clones. This was compared with the concentration where influx is 50% of maximum, a Km, for arsenate influx of 0.6 mol m−3 for tolerants and 0.025 mol m−3 for nontolerants and, therefore, phosphate was much more effective at inhibiting arsenate influx in tolerant genotypes. The high affinity phosphate uptake system is inducible under low plant phosphate status, this increasing plant phosphate status should increase tolerance by decreasing arsenate influx. Root extension in arsenate solutions of tolerant and nontolerant tillers grown under differing phosphate nutritional regimes showed that indeed, increased plant P status increased the tolerance to arsenate of both tolerant and nontolerant clones. That plant P status increased tolerance again argues that P nutrition has a critical role in arsenate tolerance. To determine if short term flux and solution culture studies were relevant to As and P accumulation in soils, soil and plant material from a range of As contaminated sites were analyzed. As predicted from the short‐term competition studies, P was accumulated preferentially to As in arsenate tolerant clones growing on mine spoil soils even when acid extractable arsenate in the soils was much greater than acid extractable phosphate. Though phosphate was much more efficient at competing with arsenate for uptake, plants growing on arsenate contaminated land still accumulated considerable amounts of As. Plants from the differing habitats showed large variation in plant phosphate status, pasture plants having much higher P levels than plants growing on the most contaminated mine spoil soils. The selectivity of the phosphate‐arsenate uptake system for phosphate compared with arsenate, coupled with the suppression of this uptake system enabled tolerant clones of the grass velvetgrass to grow on soils that were highly contaminated with arsenate and deficient in phosphate.