bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biodegradation‐Transport Interactions of Pulse Applied 2,4‐D in Repacked Soil Column Microcosms
Authors: Shaw Liz J. , Burns Richard G. 
Published: July 2010

AbstractTo predict leaching to groundwater, reliable data are needed regarding the in situ biodegradation of pesticides. Repacked soil column microcosms were used to examine the transport and biodegradation of 2,4‐dichlorophenoxyacetic acid (2,4‐D) in a noncontaminated soil profile. For columns spiked with 2,4‐D (2.4 mg) and leached with 1.81 cm d−1, maximum leachate concentrations were 4.65 mg L−1. After 30 d, 41.0% was recovered in the leachate and <0.04% by soil extraction. 2,4‐D biodegradation and the distribution and abundance of degrading microorganisms was determined by the leaching rate and the number of herbicide applications. For example, biodegradation of repeat 2,4‐D applications was enhanced: the first and second applications were degraded by 44.5 and 72.6%, respectively. This corresponded to a >103‐fold increase in numbers of 2,4‐D‐degraders at all depths following the first application. A twofold reduction in the irrigation rate also increased biodegradation from 44.5 to 77.2%. Columns of different lengths were used to quantify in situ biodegradation for discrete soil profile sections (10 cm). Subsoil biodegrdadation was higher (43.0%) in columns than it was in batch ex situ experiments (22.3%) after 30 d. The detection of 2,4‐D‐degraders in column subsoil and leachate suggests that downward transport of degrading microorganisms through the soil profile occurs, and could account for discrepancy between batch and column data.
Fecal Bacteria Survival and Infiltration through a Shallow Agricultural Soil: Timing and Tillage Effects
Authors: Stoddard C. S. , Coyne M. S. , Grove J. H. 
Published: July 2010

AbstractHuman and livestock exposure to fecal pathogens via contaminated surface or groundwater is an important water quality concern for soils receiving animal wastes. The effects of manure application timing (spring or fall application) and soil management (no‐tillage or conservation tillage) on fecal bacteria infiltration through shallow karst soils in central Kentucky (the Bluegrass region) have not been evaluated. We performed a field experiment to measure fecal coliforms and fecal streptococci in leachate from dairy manure‐amended no‐tillage and conservation tillage soils. Manure significantly increased fecal bacteria in leachate compared with unmanured treatments. After manure application, the leachate that collected in zero‐tension lysimeters 90 cm below the soil surface contained up to 6 × 104 fecal coliforms/100 mL and generally exceeded 3 × 103 fecal coliforms/100 mL. Neither the timing nor the tillage method significantly affected fecal coliform concentrations in leachate. Fecal bacteria in leachate declined to nondetectable levels within 60 d of manure application. In the well structured soil used in this experiment, fecal bacteria moved below the crop root zone whenever there was rainfall of sufficient duration or intensity to cause flow after manure application. Manure application to no‐tillage soil in spring did not accelerate water contamination by fecal coliforms relative to fall manure applications. No‐tillage did not accelerate water contamination by fecal coliforms relative to tilled soils. The potential for groundwater contamination depended on soil structure and water flow more than on fecal bacteria survival at the soil surface.
Simulating Climate Change Effects in a Minnesota Agricultural Watershed
Authors: Hanratty Michael P. , Stefan Heinz G. 
Published: July 2010

AbstractThe effect of climate change on quality and quantity of runoff from a northern, agricultural watershed was simulated using the Soil and Water Assessment Tool, 1996 Version (SWAT96). SWAT's snow evaporation submodel was modified. SWAT was calibrated using water quality and quantity data measured in the Cottonwood River near New Ulm, MN (drainage area: 3400 km2). The standard errors after calibration were 3.31 mm, 157 kg/d, 752 kg/d, 3744 kg/d, and 85 t/d for mean monthly streamfiow, P yield, ammonia (NH3)/organic N yield, nitrate (NO3) yield, and sediment yield, respectively. The standard error for monthly streamflow was 9.62 mm. SWAT96 was then used to simulate the effect on the Cottonwood River watershed of a 2xCO2 climate scenario, obtained from the Canadian Climate Center's global circulation model. Assuming land cover and land management remained constant, SWAT96 projected a decrease in mean annual streamflow, P yield, NH3/organic N yield, NO3/nitrite (NO2) yield, and sediment yield. Mean monthly values changed significantly for many months of the year under the 2xCO2 climate scenario. The standard errors in SWAT's baseline simulations, however, were too high for the simulated climate change effects to be measurable for NO3/NO2 and sediment yields. The model assumptions and calibration methods used to obtain the accuracy required for simulating the effects of climate change lead to the conclusions that land use/land cover and land management practices are likely to have a greater impact on water quality than climate change and that SWAT must be calibrated to be used for climate change analysis.
Natural Environment and Human Culture: Defining Terms and Understanding Worldviews
Authors: McIsaac G. F. , Brün M. 
Published: July 2010

AbstractThe terms nature and natural each have several different meanings, which can lead to confusion in communications about environmental issues. One approach to clarifying discussion, frequently used in the sciences, is to develop precise, operational definitions of terminology. We argue that this approach can be ineffective when applied to multi‐faceted conceptual terms such as nature, natural, and culture. We think the range of legitimate meanings for these terms may be better communicated by historical accounts of use that describe the assumptions, contexts, and woridviews associated with different interpretations. These accounts do not resolve disagreement but can help clarify the basis for it, and open up new avenues of inquiry. In this paper, we examine the terms nature, natural environment, environmental change, and environmental degradation. A recent article in this journal offered precise definitions of the last three of these terms that were based on the idea that natural is that which is relatively uninfluenced by human culture. Although this is a commonly accepted meaning of natural, we contend that this meaning needs to be carefully scrutinized. We identify specific problems with this usage and offer an account of use of the term nature, which we think provides a more thorough understanding of how nature and natural have been used and understood in different contexts. Since the term natural can be understood several different ways, communication of any particular meaning requires careful articulation of the intended meaning in light of several alternative interpretations.
Water Quality in Walnut Creek Watershed: Nitrate‐Nitrogen in Soils, Subsurface Drainage Water, and Shallow Groundwater
Authors: Cambardella C. A. , Moorman T. B. , Jaynes D. B. , Hatfield J. L. , Parkin T. B. , Simpkins W. W. , Karlen D. L. 
Published: July 2010

AbstractNonpoint source contamination of surface and groundwater resources with nitrate‐N (NO3‐N) has been linked to agriculture across the midwestern USA. A 4‐yr study was conducted to assess the extent of NO3‐N leaching in a central Iowa field. Water flow rate was monitored continuously and data were stored on an internal datalogger. Water samples for chemical analysis were collected weekly provided there was sufficient flow. Twelve soil cores were collected in spring, early summer, mid‐summer, and after harvest for each of the 4 yr. Nitrate‐N concentrations in shallow groundwater exhibited temporal trends and were higher under Clarion soil than under Okoboji or Canisteo soil. Denitrification rates were two times higher in Okoboji surface soil than in Clarion surface soil and the highest denitrificafion potential among subsurface sediments was observed for deep unoxidized loess. Soil profile NO3‐N concentrations decreased with depth and were the same below 30 cm for fertilized corn (Zea mays L.) and soybean (Glycine max L. Merr.). Nitrate‐N concentrations in subsurface drainage water exceeded 10 mg L−1 for 12 mo and were between 6 and 9 mg L−1 for 32 mo during the 4‐yr study. The temporal pattern of NO3‐N concentrations in subsurface drainage water was not related to the timing of fertilizer N application or the amount of fertilizer N applied. Total NO3‐N losses to subsurface drains were greatest in 1993 (51.3 kg ha−1) and least in 1994 (4.9 kg ha−1). Most of the subsurface drainage water NO3‐N was lost when crop plants were not present (November‐May), except in 1993. Our results indicate that NO3‐N losses to subsurface drainage water occur primarily as a result of asynchronous production and uptake of NO3‐N in the soil and the presence of large quantifies of potentially mineralizable N in the soil organic matter.
Transport of Nicosulfuron in Soil Columns
Authors: Gonzalez Javier , Ukrainczyk Ljerka 
Published: July 2010

AbstractNicosulfuron (2‐[[[[(4,6‐dimethoxy‐2‐pyrimidinyl)amino]carbonyl]amino]sulfonyl]‐N,N‐dimethyl‐3‐pyridinecarboxamide) is a relatively new sulfonylurea promoted for weed control in corn (Zea mays L.). However, there are no published studies on its transport and mobility in soils. In this study, breakthrough curves (BTCs) were measured using soil columns for eight Iowa soils and four Oxisols from Brazil. Chloride (Cl−) and pentafluorobenzoic acid (PFBA) were used as nonreactive tracers. For the sandy Iowa soils and the Brazilian soils BTCs were symmetrical, while for the nonsandy Iowa soils BTCs were asymmetrical. Breakthrough curves were interpreted using convection‐dispersion equation and equilibrium and nonequilibrium transport models. In Brazilian soils and sandy Iowa soils equilibrium models described the BTCs well. In nonsandy Iowa soils, where tailing was observed, the data were better described by a two‐site/two‐region model, indicative of nonequilibrium processes. A comparison with the Cl− and PFBA BTCs suggests that the nonequilibrium is not transport‐related. This is also supported by the low correlation between the mass transfer parameters and the partition coefficients. It is proposed that the observed nonequilibrium in nonsandy Iowa soils is most likely due to nicosulfuron chemisorption on smectites. The results of this study indicate that due to rapid sorption of nicosulfuron on smectites its potential to leach to the groundwater should be relatively low in the loamy and clayey soils that contain expandable 2:1 layer silicates.
Leaching of Broadcast and Banded Atrazine from Maize Plots
Authors: Guillard Karl , Warner Glenn S. , Kopp Kelly L. , Stake Jonathan D. 
Published: July 2010

AbstractThere are few reports that compare losses of atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methyethyl)‐1,3,5‐triazine‐2,4‐diamine] from band and broadcast applications. A field study was conducted in Connecticut to determine the leaching losses of atrazine when applied to maize (Zea mays L.) in 15‐cm bands over the rows or broadcast onto the entire plot. Estimates of leaching losses were made with zero‐tension pan lysimeters. The experiment was set out as a randomized complete block design with four replicates and treatments were method of application (broadcast vs. band) and location of lysimeters (row vs. interrow). Water samples were analyzed for atrazine and related s‐triazines using enzyme‐linked immunosorbent assay (ELISA). There was a greater (P < 0.01) frequency of water samples with atrazine detections from the broadcast application (>99%) than from the band application (82%). Atrazine concentrations also were more likely (P < 0.01) to be above the maximum contaminant level (MCL) of 3 µg L−1 from broadcast treatments (7.1%) than from band treatments (0.7%). Concentrations and mass loss of atrazine were three to four times greater (P < 0.05) in the broadcast treatment than in the band treatment. There were significant (P < 0.05) differences in concentrations and mass losses of atrazine between row and interrow locations of lysimeters for band application but not for broadcast application. Maize yield was not reduced by band atrazine application with interrow cultivation. There is less potential of groundwater contamination from atrazine when applied in a band than when applied broadcast.
Solubility and Leachability of Fishwaste Compost Phosphorus in Soilless Growing Media
Authors: Kuo S. , Hummel R. L. , Jellum E. J. , Winters D. 
Published: July 2010

AbstractKnowledge of solubility and leachability of fishwaste compost P is needed to effectively use fishwaste compost as a P source in soilless growing media. The fishwaste compost contained 3.6 g P kg−1 compost on a dry weight basis and had high P solubility, with 64.4% of the total P in the compost extractable by six successive extractions with 0.01 M NaCl. In the dilute salt solution, the Ca release from the compost paralleled that of P. The sequential extraction did not substantiate that Ca‐P was the predominant P form in the compost, because substantial amounts of P solubilized in 0.01 M NaCl were from the labile P (NH4Cl‐P) and potentially labile P (Fe‐ and Al‐P) pools. High solubility of the compost P resulted in elevation of P concentrations in leachates and cumulative amounts of P leached over 10 wk when the growing media containing 25% or more compost was irrigated with overhead sprinkler irrigation. Young rhododendron (Rhododendron fortunei ‘Scintillation’) did not significantly (P > 0.05) reduce P leaching from the 50% or higher compost treatments because the amount of P accumulated in the plant leaves represented 3 ± 0.9 (SD)% of P in the compost and P fertilizer combined. To reduce P leaching and minimize nonpoint P pollution, additions of P fertilizer to the soilless growing media containing the fishwaste compost should be restricted. Otherwise, the proportion of the compost in the media should be limited to 25% or less, unless it is used in conjunction with controlled drip irrigation.
Occurrence and Mass Balance of Polycyclic Aromatic Hydrocarbons in the Thessaloniki Sewage Treatment Plant
Authors: Manoli E. , Samara C. 
Published: July 2010

AbstractThe occurrence and the mass balance of the 16 EPA polycyclic aromatic hydrocarbons (PAHs) were investigated in a conventional activated sludge treatment plant. Polycyclic aromatic hydrocarbon concentrations were determined in wastewater and sludge samples from different treatment stages. The concentrations of PAHs in raw sewage were statistically analyzed to examine whether temporal factors (sampling period, day and hour of sampling) had a significant effect on the observed variance. Sampling period was the only factor that showed a significant impact. Principal component analysis (PCA) was used to assess similarities of the wastewater PAH pattern with possible source matrices (domestic effluents, urban runoff, and atmospheric particulates). The composition of wastewaters was found to be particularly similar to that of domestic effluents. Mass balances of PAHs were calculated for individual stages of wastewater treatment (primary treatment, secondary treatment, and chlorination), as well as for the whole treatment process. Relatively good mass balances were calculated in the primary clarifier for most PAHs. Lower molecular weight PAHs (Np, Ace, Ph, An, and Fl) showed substantial losses (>40%), in the secondary treatment probably due to biodegradation and volatilization. Good closures for all PAHs were found in the chlorination stage. Total mass balances indicated that only the lower PAHs are effectively removed, whereas the heavier compounds are rather resistant to the treatment process. Sorption was found to be the dominating removal process of PAHs—especially of the heavier ones—during primary treatment, while their removal during the secondary treatment is also governed by other processes, such as biodegradation and/or volatilization.
Ammonia Volatilization from Liquid Hog Manure Amended with Paper Products in the Laboratory
Authors: Subair S. , Fyles J. W. , O'Halloran I. P. 
Published: July 2010

AbstractLosses of N from livestock operations due to ammonia (NH3) volatilization from animal wastes is a major source of pollution in Europe and North America, and represents a significant economic loss. Paper products have potential as amendments to reduce NH3 loss because their high carbon (C) and low nitrogen (N) contents would be expected to cause N immobilization. Reduction in NH3 volatilization from liquid hog manure (LHM) by paper bag (PB), filter paper (FP), newsprint (NP), and pulp sludge (PS) added at 2.5 and 5% (fresh LHM weight) was evaluated in a 56 d incubation study. Cumulative NH3 volatilization ranged between 28 and 53% of initial manure N. When the rate increased from 2.5 to 5%, NH3 volatilization was reduced by 47, 40, 37, and 29%, respectively, compared to the control. Increasing the rate increased the amount of C lost from the LHM and reduced the net mineralization of organic N. Hence, the addition of organic amendments appeared to have decreased NH3 volatilization by increasing microbial activity and N immobilization. Liquid hog manure pH was negatively correlated with C loss, indicating that microbial decomposition of paper amendments lowered manure pH but this effect did not appear to be important in controlling NH3 volatilization. Paper lignin content was not correlated with the loss of C, manure pH, or NH3 volatilization, suggesting that the effectiveness of paper products in reducing NH3 volatilization is not controlled by lignin content but rather by other more labile components.
Irrigation of Native Rangeland Using Treated Wastewater from In Situ Uranium Processing
Authors: Levy D. B. , Kearney W. F. 
Published: July 2010

AbstractAlthough land disposal of municipal and industrial wastewater is a common practice, there is a potential for adverse environmental effects resulting from the application of some wastewaters. This study was conducted to assess the effects of rangeland irrigation using treated process waters from in situ leaching (ISL) operations at the Highland Uranium Project in Wyoming. Irrigation water quality was evaluated based on guidelines developed by the U.S. Salinity Laboratory, and concentrations of Se, B, U, and 226Ra were monitored in soil and vegetation for 6 yr. The effects of Se and B to forage grasses and wildlife were evaluated based on known toxicity thresholds obtained from the literature. Although the water is moderately saline (EC = 2.8 dS m−1), the site maintains adequate leaching to control salt accumulation in the root zone. Selenium, B, U, and 226Ra concentrations in grasses were within the natural ranges that have been documented in the literature, and were also below phytotoxic levels. Boron concentrations in both the irrigation waters and forage grasses were sufficiently low that they appear to pose no threat to livestock or waterfowl. Plant tissue Se concentrations were at or below the lowest reported tolerance level for livestock during most years, and also below the threshold for Se toxicity in pronghorn antelope. Therefore, sprinkler irrigation on rangeland appears to be a safe and practical wastewater disposal option at the Highland Uranium Project, and may be a practical method of wastewater disposal for other ISL operations as well.
Metal Solubility in Phosphogypsum‐Amended Sediment under Controlled pH and Redox Conditions
Authors: Carbonell A. A. , Porthouse J. D. , Mulbah C. K. , DeLaune R. D. , Patrick W. H. 
Published: July 2010

AbstractThe storage of phosphogypsum (PG, CaSO4 xH2O) has occupied vast areas of land that remain abandoned and subject to leaching and erosion by wind and water. The major constraints for PG use in the environment are the presence of several heavy metals and its radioactivity. Mississippi River alluvial sediment amended with PG (1%) was equilibrated under controlled redox (−250, −100, 0, 150, 300, and 500 mV) and pH (5.0 and 7.0) conditions to evaluate the feasibility of using PG to reduce aqueous concentrations of potentially toxic heavy metals and as a nutrients source. Phosphogypsum is an effective nutrient source since it increased water soluble Ca, Mg, K, and P concentrations (essential plant nutrients). At the same time, PG significantly reduced soluble Al at pH 7.0 (normal pH value of anaerobic wetland sediments), thereby reducing Al toxicity to plants growing in the sediment. Phosphogypsum addition resulted in a large increase in sulfide levels in reduced sediment suspensions. As a result, at low redox potential values, the solubility of spiked heavy metals (Cd and Ni at rates of 1000 mg kg−1) and natural trace elements was substantially reduced by precipitation as insoluble sulfides. Low sediment pH (pH 5.0) resulted in the highest release of all the studied metals [Ca, Mg, P, K, Fe, Mn, Cd, and Ni] into the sediment solution, likely due to H+, Fe2+, Mn2+, and Al3+ displacing these metals from the exchange complex. This study, therefore, indicates that PG application to Louisiana Mississippi River alluvial sediments is useful for alleviating Al toxicity (neutral pH), increasing nutrient availability under watterlogged conditions, and reducing aqueous concentrations of toxic heavy metals to trace levels under anoxic conditions by precipitating these toxic elements as insoluble sulfides. If PG or PG‐products are placed in neutral to alkaline sediments/soils and/or reducing environments, metals release at toxic levels should be of little concern to the wetland environment.
In‐Stream Wetland Mitigation of Nitrogen Contamination in a USA Coastal Plain Stream
Authors: Hunt P. G. , Stone K. C. , Humenik F. J. , Matheny T. A. , Johnson M. H. 
Published: July 2010

AbstractNonpoint source N from riverine origin is a major water quality problem throughout the world. Nitrogen removal from a contaminated (6.6 mg L−1, NO3‐N) stream was evaluated in this study using an instream wetland (ISW). The ISW was established at the exit of a 425‐ha USDA Water Quality Demonstration watershed in the Coastal Plain of North Carolina. It ranged in depth from about 0.2 to 2 m, and it was <1% (3.3 ha) the size of the watershed. The ISW dramatically lowered mean stream NO3‐N from 6.6 to 2.0 mg L−1. Nitrate‐N mass removal was highly correlated to inflow NO3‐N (r = 0.93) in the warmer months when biological processes were more active. Ammonia‐N mass removal was opposite that of NO3‐N. It was highly correlated to inflow NH3‐N (r = 0.81) during the cooler months. Removal of both NO3‐N and total‐N (NO3‐N + TKN) were positively correlated to temperature with r values of 0.77 and 0.62, respectively. Total annual N removal for the ISW was approximately 3 kg ha−1 d−1, which was about 37% of the inflow N. The ISWs appear to be very good landscape features for mitigating excess nonpoint source N in the southeastern Coastal Plain of the USA. As such, they are a good complement to other best management practices for improved water quality.