bluuebunny/crossref_metadata_2025_split huggingface dataset:
Environmental and Agronomic Implications of Water Table and Nitrogen Fertilization Management
Authors: Elmi Abdirashid A. , Madramootoo Chandra , Egeh Mohamud , Liu Aiguo , Hamel Chantal 
Published: June 2010

ABSTRACTNitrate (NO−3) pollution of surface and subsurface waters has become a major problem in agricultural ecosystems. Field trials were conducted from 1996 to 1998 at St‐Emmanuel, Quebec, Canada, to investigate the combined effects of water table management (WTM) and nitrogen (N) fertilization on soil NO−3 level, denitrification rate, and corn (Zea mays L.) grain yield. Treatments consisted of a combination of two water table treatments: free drainage (FD) with open drains at a 1.0‐m depth from the soil surface and subirrigation (SI) with a design water table of 0.6 m below the soil surface, and two N fertilizer (ammonium nitrate) rates: 120 kg N ha−1 (N120) and 200 kg N ha−1 (N200). Compared with FD, SI reduced NO−3–N concentrations in the soil profile by 37% in spring 1997 and 2% in spring 1998; and by 45% in fall 1997 and 19% in fall 1998 (1 mg NO−3–N L−1 equals approximately 4.43 mg NO−3 L−1). The higher rate of N fertilization resulted in greater levels of NO−3–N in the soil solution. Denitrification rates were higher in SI than in FD plots, but were unaffected by N rate. The N200 rate produced higher yields than N120 in 1996 and 1997, but not 1998. Corn yields in SI plots were 7% higher than FD plots in 1996 and 3% higher in 1997, but 25% lower in 1998 because the SI system was unable to drain the unusually heavy June rains, resulting in waterlogging. These findings suggest that SI can be used as an economical means of reducing NO−3 pollution without compromising crop yields during normal growing seasons.
Lead Phytoextraction from Contaminated Soil with High‐Biomass Plant Species
Authors: Shen Zhen‐Guo , Li Xiang‐Dong , Wang Chun‐Chun , Chen Huai‐Man , Chua Hong 
Published: June 2010

ABSTRACTIn this study, cabbage [Brassica rapa L. subsp. chinensis (L.) Hanelt cv. Xinza No 1], mung bean [Vigna radiata (L.) R. Wilczek var. radiata cv. VC‐3762], and wheat (Triticum aestivum L. cv. Altas 66) were grown in Pb‐contaminated soils. Application of ethylenediaminetetraacetic acid (EDTA) (3.0 mmol of EDTA/kg soil) to the soil significantly increased the concentrations of Pb in the shoots and roots of all the plants. Lead concentrations in the cabbage shoots reached 5010 and 4620 mg/kg dry matter on Days 7 and 14 after EDTA application, respectively. EDTA was the best in solubilizing soil‐bound Pb and enhancing Pb accumulation in the cabbage shoots among various chelates (EDTA, diethylenetriaminepentaacetic acid [DTPA], hydroxyethylenediaminetriacetic acid [HEDTA], nitrilotriacetic acid [NTA], and citric acid). Results of the sequential chemical extraction of soil samples showed that the Pb concentrations in the carbonate–specifically adsorbed and Fe–Mn oxide phases were significantly decreased after EDTA treatment. The results indicated that EDTA solubilized Pb mainly from these two phases in the soil. The relative efficiency of EDTA enhancing Pb accumulation in shoots (defined as the ratio of shoot Pb concentration to EDTA concentration applied) was highest when 1.5 or 3.0 mmol EDTA/kg soil was used. Application of EDTA in three separate doses was most effective in enhancing the accumulation of Pb in cabbage shoots and decreased mobility of Pb in soil compared with one‐ and two‐dose application methods. This approach could help to minimize the amount of chelate applied in the field and to reduce the potential risk of soluble Pb movement into ground water.
Impacts of Golf Courses on Macroinvertebrate Community Structure in Precambrian Shield Streams
Authors: Winter Jennifer G. , Somers Keith M. , Dillon Peter J. , Paterson Carolyn , Reid Ron A. 
Published: June 2010

ABSTRACTThe influence of golf course operation on benthic macroinvertebrate communities in Precambrian Shield streams was evaluated using rapid bioassessment and the reference condition approach. Streams were sampled for water chemistry and invertebrates in 1999 and 2000, six on operational golf courses, and seven in forested reference locations. Correspondence analysis (CA) was used to determine the major patterns in the macroinvertebrate taxa, and canonical correspondence analysis (CCA) was used to evaluate relationships with environmental variables. The reference streams were used to define the normal range of variation for a variety of summary indices to evaluate the golf course streams. In all cases, golf course streams were higher in nutrients and dissolved ions and more alkaline than the forested reference streams. There was considerable variability in the macroinvertebrate fauna from the golf course streams, which was related to differences in golf course land management practices and to the potential influence of highway runoff. Of the management practices evaluated, fertilizer application rates in particular were important, as was the presence of ponds upstream on the course. Invertebrate taxa with higher abundances in golf course streams included Turbellaria, Isopoda, Amphipoda, Zygoptera, and Trombidiformes. Taxa more common in the reference streams included Ephemeroptera, Megaloptera, Culicidae, and Plecoptera. There were marked differences in the overall benthic macroinvertebrate community in three of the six golf course streams studied relative to the forested reference streams, suggesting that golf course land management on the Precambrian Shield can be associated with significant differences in macroinvertebrate community structure.
Effects of Prolonged Irrigation with Treated Municipal Effluent on Runoff Rate
Authors: Agassi M. , Tarchitzky J. , Keren R. , Chen Y. , Goldstein D. , Fizik E. 
Published: June 2010

ABSTRACTThe use of domestic effluents for the irrigation of crops has been widespread in Israel for the past 30 years. The sodium adsorption ratio (SAR) of the standardized domestic effluents ranges between 4 and 6. According to the literature, when soils with SAR levels of 4 to 6 are exposed to direct raindrop impact they are subjected to enhanced aggregate disintegration, leading to sealing processes of the soil surface and subsequent increased runoff and soil erosion. However, these phenomena were not observed in the laboratory and field experiments of this study. On the other hand, a rapid decrease of the soil SAR to its initial values was observed, in laboratory and fieldwork, once the soil was subjected to a simulated rainstorm of distilled water (laboratory) or natural rainstorms (field plots). We can conclude that the process of SAR increase during irrigation with standardized effluent water is reversible. Further investigation in this direction can lead to recommendations regarding the necessary levels of domestic sewage water purification in correlation with soil types, climatic conditions, and hazards to tap water aquifers.
Denitrification Potential in Urban Riparian Zones
Authors: Groffman Peter M. , Crawford Marshall Kamau 
Published: June 2010

ABSTRACTDenitrification, the anaerobic microbial conversion of nitrate NO−3to nitrogen (N) gases, is an important process contributing to the ability of riparian zones to function as “sinks” for NO−3in watersheds. There has been little analysis of riparian zones in urban watersheds despite concerns about high NO−3concentrations in many urban streams. Vegetation and soils in urban ecosystems are often highly disturbed, and few studies have examined microbial processes like denitrification in these ecosystems. In this study, we measured denitrification potential and a suite of related microbial parameters (microbial biomass carbon [C] and N content, potential net N mineralization and nitrification, soil inorganic N pools) in four rural and four urban riparian zones in the Baltimore, MD metropolitan area. Two of the riparian zones were forested and two had herbaceous vegetation in each land use context. There were few differences between urban and rural and herbaceous and forest riparian zones, but variability was much higher in urban than rural sites. There were strong positive relationships between soil moisture and organic matter content and denitrification potential. Given the importance of surface runoff in urban watersheds, the high denitrification potential of the surface soils that we observed suggests that if surface runoff can be channeled through areas with high denitrification potential (e.g., stormwater detention basins with wetland vegetation), these areas could function as important NO−3sinks in urban watersheds.
Nitrous Oxide Emission and Denitrification in Chronically Nitrate‐Loaded Riparian Buffer Zones
Authors: Hefting Mariet M. , Bobbink Roland , de Caluwe Hannie 
Published: June 2010

ABSTRACTRiparian buffer zones are known to reduce diffuse N pollution of streams by removing and modifying N from agricultural runoff. Denitrification, often identified as the key N removal process, is also considered as a major source of the greenhouse gas nitrous oxide (N2O). The risks of high N2O emissions during nitrate mitigation and the environmental controls of emissions have been examined in relatively few riparian zones and the interactions between controls and emissions are still poorly understood. Our objectives were to assess the rates of N2O emission from riparian buffer zones that receive large loads of nitrate, and to evaluate various factors that are purported to control N emissions. Denitrification, nitrification, and N2O emissions were measured seasonally in grassland and forested buffer zones along first‐order streams in the Netherlands. Lateral nitrate loading rates were high, up to 470 g N m−2 yr−1 Nitrogen process rates were determined using flux chamber measurements and incubation experiments. Nitrous oxide emissions were found to be significantly higher in the forested (20 kg N ha−1 yr−1) compared with the grassland buffer zone (2–4 kg N ha−1 yr−1), whereas denitrification rates were not significantly different. Higher rates of N2O emissions in the forested buffer zone were associated with higher nitrate concentrations in the ground water. We conclude that N transformation by nitrate‐loaded buffer zones results in a significant increase of greenhouse gas emission. Considerable N2O fluxes measured in this study indicate that Intergovernmental Panel on Climate Change methodologies for quantifying indirect N2O emissions have to distinguish between agricultural uplands and riparian buffer zones in landscapes receiving large N inputs.
Chromate Reduction by Chromium‐Resistant Bacteria Isolated from Soils Contaminated with Dichromate
Authors: Camargo F. A. O. , Bento F. M. , Okeke B. C. , Frankenberger W. T. 
Published: June 2010

ABSTRACTExtensive use of hexavalent chromium [Cr(VI)] in various industrial applications has caused substantial environmental contamination. Chromium‐resistant bacteria isolated from soils can be used to remove toxic Cr(VI) from contaminated environments. This study was conducted to isolate chromium‐resistant bacteria from soils contaminated with dichromate and describes the effects of some environmental factors such as pH, temperature, and time on Cr(VI) reduction and resistance. We found that chromium‐resistant bacteria can tolerate 2500 mg L−1 Cr(VI), but most of the isolates tolerated and reduced Cr(VI) at concentrations lower than 1500 mg L−1 Chromate reduction activity of whole cells was detected in five isolates. Most of these isolates belong to the genus Bacillus as identified by the 16S rRNA gene sequencing. Maximal Cr(VI) reduction was observed at the optimum pH (7.0–9.0) and temperature (30°C) of growth. One bacterial isolate (Bacillus sp. ES 29) was able to aerobically reduce 90% of Cr(VI) in six hours. The Cr(VI) reduction activity of the whole cells of five isolates had a KM of 0.271 (2.61 mM) to 1.51 mg L−1 (14.50 mM) and a Vmax of 88.4 (14.17 nmol min−1) to 489 mg L−1 h−1 (78.36 nmol min−1). Our consortia and monocultures of these isolates can be useful for Cr(VI) detoxification at low and high concentrations in Cr(VI)‐contaminated environments and under a wide range of environmental conditions.
Soil Mixing to Decrease Surface Stratification of Phosphorus in Manured Soils
Authors: Sharpley Andrew N. 
Published: June 2010

ABSTRACTContinual applications of fertilizer and manure to permanent grassland or no‐till soils can lead to an accumulation of P at the surface, which in turn increases the potential for P loss in overland flow. To investigate the feasibility of redistributing surface stratified P within the soil profile by plowing, Mehlich‐3 P rich surface soils (128–961 mg kg−1in 0–5 cm) were incubated with lower‐P subsoil (16–119 mg kg−1in 5–20 cm) for 18 manured soils from Oklahoma and Pennsylvania that had received long‐term manure applications (60–150 kg P ha−1yr−1as dairy, poultry, or swine manure for up to 20 yr). After incubating a mixture of 5 g surface soil (0‐ to 5‐cm depth) and 15 g subsoil (5‐ to 20‐cm depth) for 28 d, Mehlich‐3 P decreased 66 to 90% as a function of the weighted mean Mehlich‐3 P of surface and subsoil (i.e., 1:3 ratio) (r2= 0.87). At Klingerstown, Northumberland County, south central Pennsylvania, a P‐stratified Berks soil (Typic Dystrochrept) (495 mg kg−1Mehlich‐3 P in 0‐ to 5‐cm depth) was chisel plowed to about 25 cm and orchardgrass (Dactylis glomerataL.) planted. Once grass was established and erosion minimized (about 20 wk after plowing and planting), total P concentration in overland flow during a 30‐min rainfall (6.5 cm h−1) was 1.79 mg L−1compared with 3.4 mg L−1before plowing, with dissolved P reduced from 2.9 to 0.3 mg L−1Plowing P‐stratified soils has the potential to decrease P loss in overland flow, as long as plowing‐induced erosion is minimized.
Phosphorus Runoff
Authors: Daverede I. C. , Kravchenko A. N. , Hoeft R. G. , Nafziger E. D. , Bullock D. G. , Warren J. J. , Gonzini L. C. 
Published: June 2010

ABSTRACTContinued inputs of fertilizer and manure in excess of crop requirements have led to a build‐up of soil phosphorus (P) levels and increased P runoff from agricultural soils. The objectives of this study were to determine the effects of two tillage practices (no‐till and chisel plow) and a range of soil P levels on the concentration and loads of dissolved reactive phosphorus (DRP), algal‐available phosphorus (AAP), and total phosphorus (TP) losses in runoff, and to evaluate the P loss immediately following tillage in the fall, and after six months, in the spring. Rain simulations were conducted on a Typic Argiudoll under a corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation. Elapsed time after tillage (fall vs. spring) was not related to any form of P in runoff. No‐till runoff averaged 0.40 mg L−1 and 0.05 kg ha−1 DRP and chisel‐plow plots averaged 0.24 mg L−1 and 0.02 kg ha−1 DRP concentration and loads, respectively. The relationship between DRP and Bray P1 extraction values was approximated by a logistic function (S‐shaped curve) for no‐till plots and by a linear function for tilled plots. No significant differences were observed between tillage systems for TP and AAP in runoff. Bray P1 soil extraction values and sediment concentration in runoff were significantly related to the concentrations and amounts of AAP and TP in runoff. These results suggest that soil Bray P1 extraction values and runoff sediment concentration are two easily measured variables for adequate prediction of P runoff from agricultural fields.
Predicting Nitrate Leaching under Potato Crops Using Transfer Functions
Authors: Gasser M. O. , Caron J. , Lagacé R. , Laverdière M. R. 
Published: June 2010

ABSTRACTNitrate leaching is a major issue in many cultivated soils. Models that predict the major processes involved at the field scale could be used to test and improve management practices. This study aims to evaluate a simple transfer function approach to predict nitrate leaching in sandy soils. A convective lognormal transfer (CLT) function is convoluted with functional equations simulating N mineralization, plant N uptake, N fertilizer dissolution, and nitrification at the soil surface to predict solute concentrations under potato (Solanum tuberosumL.) and barley (Hordeum vulgareL.) fields as a function of drainage water. Using this approach, nitrate flux concentrations measured in drainable lysimeters (1‐m soil depth) were reasonably predicted from 29 Apr. 1996 to 3 Dec. 1996. With average application rates of 16.9 g m−2of N fertilizer in potato crops, mean nitrate‐leaching losses measured under potato were 8.5 g N m−2Tuber N uptake averaged 9.7 g N m−2and soil mineral N at start (spring) and end (fall) of N mass balance averaged 1.7 and 4.5 g N m−2, respectively. Soil N mineralization was estimated by difference (4.3 g N m−2on average) and was small compared with N fertilization. Small nitrate flux concentrations at the beginning of the cropping season (May) resulted mainly from initial soil nitrate concentrations. Measured and predicted nitrate flux concentrations significantly increased at mid‐season (July–August) following important drainage events coupled with complete dissolution and nitrification of N fertilizers, and declining N uptake by potato plants. Decreases in nitrate concentrations before the end of year (November–December) underlined the predominant effect of N fertilizers applied for the most part at planting acting as a pulse input of solute.
Potential Environmental Benefits of Ionophores in Ruminant Diets
Authors: Tedeschi Luis Orlindo , Fox Danny Gene , Tylutki Thomas Paul 
Published: June 2010

ABSTRACTA concern of the USEPA is the volatilization of NH3 from animal manure and CH4 produced from ruminal fermentation. Excess N in the environment has been associated with adverse effects on human health, and CH4 and N2O emissions are sources of greenhouse gases. The objectives of this paper are to summarize and quantify the benefits of ionophores, principally monensin, in decreasing NH3 and CH4 emissions to the environment and reducing resource utilization in cattle (Bos spp.) production. The data indicate that monensin in the diets of ruminants may decrease protein degradation in the rumen and may increase feed protein utilization by an average of 3.5 percentage units. These changes would have an effect in reducing N losses and decreasing fecal N and the amount of protein that must be fed to meet animal requirements. Additionally, CH4 is produced by enteric fermentation in ruminants, which is responsible for about 33 to 39% of CH4 emissions from agriculture. Ionophores can reduce CH4 production by 25% and decrease feed intake by 4% without affecting animal performance. The inclusion of monensin in beef and dairy cattle diets may benefit air quality by reducing CH4 and N emissions and water quality by reducing N in manure, which can potentially leave the farm through leaching into ground water and through runoff into surface water.
In Situ Reduction of Chromium(VI) in Heavily Contaminated Soils through Organic Carbon Amendment
Authors: Tokunaga Tetsu K. , Wan Jiamin , Firestone Mary K. , Hazen Terry C. , Olson Keith R. , Herman Donald J. , Sutton Stephen R. , Lanzirotti Antonio 
Published: June 2010

ABSTRACTChromium has become an important soil contaminant at many sites, and facilitating in situ reduction of toxic Cr(VI) to nontoxic Cr(III) is becoming an attractive remediation strategy. Acceleration of Cr(VI) reduction in soils by addition of organic carbon was tested in columns pretreated with solutions containing 1000 and 10 000 mg L−1Cr(VI) to evaluate potential in situ remediation of highly contaminated soils. Solutions containing 0, 800, or 4000 mg L−1organic carbon in the form of tryptic soy broth or lactate were diffused into the Cr(VI)‐contaminated soils. Changes in Cr oxidation state were monitored through periodic micro‐XANES analyses of soil columns. Effective first‐order reduction rate constants ranged from 1.4 × 10−8to 1.5 × 10−7s−1, with higher values obtained for lower levels of initial Cr(VI) and higher levels of organic carbon. Comparisons with sterile soils showed that microbially dependent processes were largely responsible for Cr(VI) reduction, except in the soils initially exposed to 10 000 mg L−1Cr(VI) solutions that receive little (800 mg L−1) or no organic carbon. However, the microbial populations (≤2.1 × 105g−1) in the viable soils are probably too low for direct enzymatic Cr(VI) reduction to be important. Thus, synergistic effects sustained in whole soil systems may have accounted for most of the observed reduction. These results show that acceleration of in situ Cr(VI) reduction with addition of organic carbon is possible in even heavily contaminated soils and suggest that microbially dependent reduction pathways can be dominant.
Evaluation of Water Treatment Sludge for Ameliorating Acid Mine Waste
Authors: Van Rensburg L. , Morgenthal T. L. 
Published: June 2010

ABSTRACTThis study investigated the liming effect of water treatment sludge on acid mine spoils. The study was conducted with sludge from a water purification plant along the Vaal River catchments in South Africa. The optimum application rate for liming acid spoils and the speed and depth with which the sludge reacted with the mine waste were investigated. Chemical analysis indicated that the sludge is suitable as a liming agent because of its alkaline pH (8.08), high bicarbonate concentration (183.03 mg L−1), and low salinity (electrical conductivity = 76 mS m−1). The high cation exchange capacity of 15.47 cmolckg−1and elevated nitrate concentration (73.16 mg L−1) also increase its value as an ameliorative material. The soluble concentrations for manganese, aluminum, lead, and selenium were high at a pH of 5 although only selenium (0.83 mg L−1) warranted some concern. According to experimental results, the application of 10 Mg ha−1of sludge to acid gold tailings increased the leach water pH from 4.5 to more than 7.5 and also increased the medium pH from 2.4 to 7.5. The addition of sludge further reduced the solubility of iron, manganese, copper, and zinc in the ameliorated gold tailings, but increased the electrical conductivity. The liming tempo was highest in the coal discard profile that had a coarse particle size distribution and took the longest to move through the gold tailings that had a fine particle size distribution. Results from this study indicate that the water treatment sludge investigated is suitable as a liming agent for rehabilitation of acid mine waste.
Effect of Soil Properties on Saturated and Unsaturated Virus Transport through Columns
Authors: Chu Yanjie , Jin Yan , Baumann Thomas , Yates Marylynn V. 
Published: June 2010

ABSTRACTViruses from contaminant sources can be transported through porous media to drinking water wells. The objective of this study was to investigate inactivation and sorption of viruses during saturated and unsaturated transport in different soils. Bacteriophages φX174 and MS‐2, and Br− tracer in a phosphate‐buffered saline solution were introduced into saturated and unsaturated soil columns as a step function under constant flow rate and hydraulic conditions. Results showed that significantly greater virus removal occurred in the unsaturated columns than in the saturated columns in the two soils containing high metal oxides content. However, the increase in virus retention under unsaturated conditions was not significant in two other soils having high phosphorus and calcium contents and high pH, and in another soil with high organic matter content. The results imply that the extent of water content effect on inactivation and sorption of viruses can range from significant to minimal depending on the properties of the transport medium. We found that the presence of in situ metal oxides was a significant factor responsible for virus sorption and inactivation. Therefore, soils with high metal oxides content may have the potential to be used as hydrological barriers in preventing microbial contamination in the subsurface environments. We also found that the water content effect on virus removal and inactivation strongly depended on solid properties of the testing medium.