bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Biological Air Filters for Livestock Ventilation Air by Membrane Inlet Mass Spectrometry
Authors: Feilberg Anders , Adamsen Anders P. S. , Lindholst Sabine , Lyngbye Merete , Schäfer Annette
Published: April 2010

Biological air filters have been proposed as a cost‐effective technology for reducing odor emissions from intensive swine production facilities. In this work we present results from the application of membrane inlet mass spectrometry (MIMS) for continuously monitoring the removal of odorous compounds in biological air filters. The sensitivity and selectivity were tested on synthetic samples of selected odorous compounds, and linearity and detection limits in the lower ppb range were demonstrated for all compounds tested (methanethiol, dimethyl sulfide, carboxylic acids, 4‐methylphenol, aldehydes, indole, and skatole) except trimethylamine. The method was applied in situ at two full‐scale filters installed at swine houses. The results have been compared with analyses by thermal desorption gas chromatography–mass spectrometry (TD‐GC/MS), and odor was measured by olfactometry. By comparison with TD‐GC/MS, observed MIMS signals were assigned to 4‐methylphenol, 4‐ethylphenol, indole, skatole, the sum of volatile reduced organic sulfur compounds (ROS), and three subgroups of carboxylic acids. The removal rates were observed to be related to air–water partitioning with removal efficiencies in the range of 0 to 50% for low‐soluble organic sulfur compounds and high removal efficiencies (typically 80–100%) for more soluble phenols and carboxylic acids. Based on the results and published odor threshold values, it is estimated that the low removal efficiency of ROS is the main limitation for achieving a higher odor reduction.
Microbial Transport from Dairying under Two Spray‐Irrigation Systems in Canterbury, New Zealand
Authors: Close Murray , Noonan Mike , Hector Ross , Bright John
Published: April 2010

Transport through the soil and vadose zone to groundwater of Escherichia coli, fecal coliforms, and Campylobacter spp. from pasturing of dairy cows was studied on two working dairy farms under a traveling irrigator and a center pivot system. Leachate was collected from 1.5 m depth using a large linear lysimeter over a period of 4 yr after rainfall or irrigation applied using a traveling irrigator. There was little transport of fecal coliforms or Campylobacter from irrigation applications of 55 mm. There was some transport of fecal coliforms at applications of 80 mm (corresponding to irrigation plus heavy rainfall) but no detectable Campylobacter When fresh cow pats were placed on half of the lysimeter plots with an 80‐mm water application, there was transport of fecal coliforms and Campylobacter, but levels of Campylobacter were low (≤4 MPN L−1). Groundwater at the farm with center pivot spray irrigation was monitored monthly from September 2001 to June 2007, with 60% of samples being collected from downgradient wells. Escherichia coli were detected in 5.4 and 2.8% of samples from upgradient and downgradient wells, respectively, at concentrations of ≥1 cfu 100 mL−1 Campylobacter was detected in 0.7% of samples over the study period, with equal percentages from up‐ and downgradient wells. The results indicate minimal impact of dairying at these sites on microbial quality of groundwater as a result of spray irrigation using traveling irrigators at rates of approximately 55 mm every 2 wk or center pivot irrigators at 18 mm every 3 to 4 d.
Distribution, Chemical Speciation, and Mobility of Lead and Antimony Originating from Small Arms Ammunition in a Coarse‐Grained Unsaturated Surface Sand
Authors: Lewis Jeffrey , Sjöström Jan , Skyllberg Ulf , Hägglund Lars
Published: April 2010

This study quantified the heavy metal contamination caused by firing 500 high‐velocity 7.62‐mm jacketed Swedish military rounds. Contamination of solid and aqueous phases was studied, with Pb and Sb being the two contaminants of primary interest. The distribution of the Pb and Sb were measured in terms of depth of penetration in sand and grain size distribution of the bullet particles. The Pb‐ and Sb‐contaminated sand was then used as a source material in two bench‐scale unsaturated lysimeters to measure the transport of Pb and Sb through two coarse‐grained sands, which were taken from the berms on two Swedish military small arms ranges. The lysimeters were subjected to an infiltration cycle that reproduced spring snowmelt, which is the most significant infiltration event of the year in northern climates. The levels of mobile Pb and Sb were monitored in the effluent from the lysimeters. Extended X‐ray absorption fine‐structure spectroscopy analysis was performed on the contaminated sands to determine Pb speciation before and after leaching. Ninety‐three percent of the mass of bullets was found in the top 30 cm of sand. Lead oxide was the predominant species of Pb before and after leaching. Transport of Pb was small, with aqueous concentrations remaining stable at <2 μg L−1 Antimony was far more mobile, with solute breakthrough occurring between 5 and 14 d and concentrations rising to over 125 μg L−1 within 1 month.
Elephant Trail Runoff and Sediment Dynamics in Northern Thailand
Authors: Sidle Roy C. , Ziegler Alan D.
Published: April 2010

Although elephants may exert various impacts on the environment, no data are available on the effects of elephant trails on runoff, soil erosion, and sediment transport to streams during storms. We monitored water and sediment fluxes from an elephant trail in northern Thailand during seven monsoon storms representing a wide range of rainfall energies. Runoff varied from trivial amounts to 353 mm and increased rapidly in tandem with expanding contributing areas once a threshold of wetting occurred. Runoff coefficients during the two largest storms were much higher than could be generated from the trail itself, implying a 4.5‐ to 7.9‐fold increase in the drainage areas contributing to storm runoff. Clockwise hysteresis patterns of suspended sediment observed during most storms was amplified by a “first flush” of sediment early on the hydrograph in which easily entrained sediment was transported. As runoff areas expanded during the latter part of large storms, discharge increased but sediment concentrations declined. Thus, sediment flux was better correlated to kinetic energy of rainfall on the falling limbs of most storm hydrographs compared to rising limbs. Based on a power function relationship between sediment flux and storm kinetic energy, the estimated annual sediment yield from the trail for 135 storms in 2005 was 308 to 375 Mg ha−1 yr−1, higher than from most disturbed land surfaces in the tropics. The eight largest storms (30% of total storm energy) in 2005 transported half of the total annual sediment. These measurements together with site investigations reveal that highly interconnected elephant trails, together with other source areas, directly link runoff and sediment to streams.
Conventional and Conservation Tillage: Influence on Seasonal Runoff, Sediment, and Nutrient Losses in the Canadian Prairies
Authors: Tiessen K. H. D. , Elliott J. A. , Yarotski J. , Lobb D. A. , Flaten D. N. , Glozier N. E.
Published: April 2010

Conservation tillage has been widely promoted to reduce sediment and nutrient transport from agricultural fields. However, the effect of conservation tillage on sediment and nutrient export in snowmelt‐dominated climates is not well known. Therefore, a long‐term paired watershed study was used to compare sediment and nutrient losses from a conventional and a conservation tillage watershed in the Northern Great Plains region of western Canada. During the treatment period, dissolved nutrient concentrations were typically greater during spring snowmelt than during summer rainfall events, whereas concentrations of sediment and particulate nutrients were greatest during rainfall events. However, because total runoff was dominated by snowmelt, most sediment and nutrient export occurred during snowmelt. Overall, conservation tillage reduced the export of sediment in runoff water by 65%. Similarly, concentrations and export of nitrogen were reduced by 41 and 68%, respectively, relative to conventional tillage. After conversion to conservation tillage, concentrations and exports of phosphorus (P) increased by 42 and 12%, respectively, with soluble P accounting for the majority of the exported P, especially during snowmelt. Our results suggest that management practices designed to improve water quality by reducing sediment and sediment‐bound nutrient export from agricultural fields and watersheds can be less effective in cold, dry regions where nutrient export is primarily snowmelt driven and in the dissolved form. In these situations, it may be more appropriate to implement management practices that reduce the accumulation of nutrients in crop residues and the surface soil.
Tillage, Cropping Sequence, and Nitrogen Fertilization Effects on Dryland Soil Carbon Dioxide Emission and Carbon Content
Authors: Sainju Upendra M. , Jabro Jalal D. , Caesar‐TonThat Thecan
Published: April 2010

Management practices are needed to reduce dryland soil CO2 emissions and to increase C sequestration. We evaluated the effects of tillage and cropping sequence combinations and N fertilization on dryland crop biomass (stems + leaves) and soil surface CO2 flux and C content (0‐ to 120‐cm depth) in a Williams loam from May to October, 2006 to 2008, in eastern Montana. Treatments were no‐tilled continuous malt barley (Hordeum vulgaris L.) (NTCB), no‐tilled malt barley–pea (Pisum sativum L.) (NTB‐P), no‐tilled malt barley–fallow (NTB‐F), and conventional‐tilled malt barley–fallow (CTB‐F), each with 0 and 80 kg N ha−1 Measurements were made both in Phase I (malt barley in NTCB, pea in NTB‐P, and fallow in NTB‐F and CTB‐F) and Phase II (malt barley in all sequences) of each cropping sequence in every year. Crop biomass varied among years, was greater in the barley than in the pea phase of the NTB‐P treatment, and greater in NTCB and NTB‐P than in NTB‐F and CTB‐F in 2 out of 3 yr. Similarly, biomass was greater with 80 than with 0 kg N ha−1 in 1 out of 3 yr. Soil CO2 flux increased from 8 mg C m−2 h−1 in early May to 239 mg C m−2 h−1 in mid‐June as temperature increased and then declined to 3 mg C m−2 h−1 in September–October. Fluxes peaked immediately following substantial precipitation (>10 mm), especially in NTCB and NTB‐P. Cumulative CO2 flux from May to October was greater in 2006 and 2007 than in 2008, greater in cropping than in fallow phases, and greater in NTCB than in NTB‐F. Tillage did not influence crop biomass and CO2 flux but N fertilization had a variable effect on the flux in 2008. Similarly, soil total C content was not influenced by treatments. Annual cropping increased CO2 flux compared with crop–fallow probably by increasing crop residue returns to soils and root and rhizosphere respiration. Inclusion of peas in the rotation with malt barley in the no‐till system, which have been known to reduce N fertilization rates and sustain malt barley yields, resulted in a CO2 flux similar to that in the CTB‐F sequence.
Organic Waste Effects on the Behavior of 17β‐estradiol, Estrone, and 17α‐ethinylestradiol in Agricultural Soils in Long‐ and Short‐Term Setups
Authors: Stumpe Britta , Marschner Bernd
Published: April 2010

Natural and synthetic estrogens can reach agricultural soils with manures, biosolids, or wastewater. This study evaluates (i) the effects of long‐term field application of such organic soil amendments and (ii) the short‐term effects of 14 different organic amendments in one agricultural soil on mineralization and sorption of 14C‐labeled 17β‐estradiol, estrone, and 17α‐ethinylestradiol. Long‐term organic waste applications resulted in increasing soil organic carbon (SOC) contents, causing increased estrogen sorption. The mineralization of the estrogens was enhanced by up to 147% or depressed by up to 50%, depending on site and organic waste, but not related to changes in sorption parameters. Short‐term organic waste amendments directly increased estradiol mineralization to up to 70% in the treated soil compared with 5% in the untreated control. Estradiol sorption increased with the amount of incorporated organic waste, but the log Koc values of 3.1–3.2 L kg−1 for organic wastes showed a lower sorption potential for estrogens compared with 3.5 L kg−1 in the untreated soil. The effects of organic waste amendments on estrogen behavior depend on amendment type and aging. Short‐term organic waste applications to soil resulted in enhanced microbial estrogen mineralization likely due to cometabolic processes. In soils with a long history of organic waste amendments, the controlling factor for estrogen sorption is an increased SOC content. The observed positive or negative effects on estrogen mineralization in these soils are not well understood. Surprisingly, the increase in estrogen sorption to the soil solid phase either through short‐term or long‐term organic waste application does not control estrogen mineralization.
Runoff Losses of Suspended Sediment, Nitrogen, and Phosphorus from a Small Watershed in Korea
Authors: Chun Jong A. , Cooke Richard A. , Kang Moon S. , Choi Minha , Timlin Dennis , Park Seung W.
Published: April 2010

Nutrients and sediments in runoff lead to the degradation of water quality of lakes and streams. The development of schemes to mitigate such degradation requires a characterization of the underlying transport processes. The objectives of this study were to develop annual and seasonal load–discharge relationships for suspended sediment (SS), total nitrogen (TN), and total phosphorus (TP) losses from a small mixed land use watershed and to use these relationships to explicate the annual and monthly patterns of losses of these species. Data from 1996 to 2004 were used to develop load–discharge relationships for SS, TN, and TP at the HP#6 watershed, a subwatershed of the Balhan reservoir watershed located in Bongdam‐myun and Paltan‐myun, Gyeonggi‐do, Korea. Standard least squares curve fitting and S‐estimation procedures were used to fit power functions to the data collected over this time period. The fitted load–discharge relationships are indicative of seasonal variations in SS and TN and of TP losses from HP#6. The exponents of the fitted power functions for TN and TP in the fall, for TP in summer season, and for SS in all seasons are >1, indicating that the concentrations of these species increase as flow rate increases. Most of the SS, TN, and TP transported in runoff left the watershed between April and September; thus, cost‐efficient strategies can be established by focusing on this period. Further study of the seasonal variations is required for a better characterization of seasonal losses of SS, TN, and TP in runoff from the HP#6 watershed.
Acidity Decay of Above‐Drainage Underground Mines in West Virginia
Authors: Mack B. , McDonald L. M. , Skousen J.
Published: April 2010

Acidity of water from abandoned underground mines decreases over time, and the rate of decrease can help formulate remediation approaches and treatment system designs. The objective of this study was to determine an overall acidity decay rate for above‐drainage underground mines in northern West Virginia from a large data set of mines that were closed 50 to 70 yr ago. Water quality data were obtained from 30 Upper Freeport and 7 Pittsburgh coal seam mines in 1968, 1980, 2000, and 2006, and acidity decay curves were calculated. The mean decay constant, k, for Upper Freeport mines was 2.73 × 10−2 yr−1, with a 95% confidence interval of ± 0.0052, whereas the k value for Pittsburgh mines was not significantly different at 4.26 × 10−2 yr−1 ± 0.017. Acidity from the T&T mine, which was closed 12 yr ago, showed a k value of 11.25 × 10−2 yr−1 This higher decay rate was likely due to initial flushing of accumulated metal salts on reaction surfaces in the mine, rapid changes in mine hydrology after closure, and treatment. Although each site showed a specific decay rate (varying from 0.04 × 10−2 yr−1 to 13.1 × 10−2 yr−1), the decay constants of 2.7 × 10−2 yr−1 to 4.3 × 10−2 yr−1 are useful for predicting water quality trends and overall improvements across a wide spectrum of abandoned underground mines. We found first‐order decay models improve long‐term prediction of acidity declines from above‐drainage mines compared with linear or percent annual decrease models. These predictions can help to select water treatment plans and evaluate costs for these treatments over time.
Influence of Streambank Fencing on the Environmental Quality of Cattle‐Excluded Pastures
Authors: Miller J. J. , Chanasyk D. S. , Curtis T. , Willms W. D.
Published: April 2010

Limited information exists on the effect of streambank fencing on riparian zone pastures. The objective of this study was to test the hypothesis that 4 to 6 yr of streambank fencing would improve the environmental quality of the cattle‐excluded pasture compared with the grazed pasture and cause the fenced pasture to act as a buffer or filter strip. Rangeland health, vegetative and soil properties, and rainfall simulation runoff were measured in the cattle‐excluded and adjacent grazed native pastures along the fenced reach of the Lower Little Bow River in southern Alberta, Canada, for 3 yr (2005–2007). Rangeland health was improved (health score increase from 55 to 72%); vegetation cover (13–21%) and standing litter (38–742%) were increased; and bare soil (72–93%) and soil bulk density (6–8%) were decreased under cattle exclusion, indicating an improvement in environmental quality from streambank fencing. In contrast, other vegetation (total and live basal area, fallen litter) and soil properties (soil water and soil C, N, and P) were not improved by cattle exclusion. Cattle exclusion significantly (P ≤ 0.10) reduced surface runoff depth of water (21–32%) and mass loads of total N fractions (21–52%) in 2 of 3 yr compared with the grazed pasture, suggesting that this fenced pasture may act as a buffer for certain runoff variables. In contrast, other runoff variables (turbidity, electrical conductivity, pH, concentrations and loads of total suspended solids, and certain N and P fractions) in the cattle‐excluded pasture were generally not improved by streambank fencing. Overall, streambank fencing improved the quality of certain environmental variables within the cattle‐excluded pasture.
Effect of Intercropping Period Management on Runoff and Erosion in a Maize Cropping System
Authors: Laloy Eric , Bielders C. L.
Published: April 2010

The management of winter cover crops is likely to influence their performance in reducing runoff and erosion during the intercropping period that precedes spring crops but also during the subsequent spring crop. This study investigated the impact of two dates of destruction and burial of a rye (Secale cereale L.) and ryegrass (Lolium multiflorum Lam.) cover crop on runoff and erosion, focusing on a continuous silage maize (Zea mays L.) cropping system. Thirty erosion plots with various intercrop management options were monitored for 3 yr at two sites. During the intercropping period, cover crops reduced runoff and erosion by more than 94% compared with untilled, post‐maize harvest plots. Rough tillage after maize harvest proved equally effective as a late sown cover crop. There was no effect of cover crop destruction and burial dates on runoff and erosion during the intercropping period, probably because rough tillage for cover crop burial compensates for the lack of soil cover. During two of the monitored maize seasons, it was observed that plots that had been covered during the previous intercropping period lost 40 to 90% less soil compared with maize plots that had been left bare during the intercropping period. The burial of an aboveground cover crop biomass in excess of 1.5 t ha−1 was a necessary, yet not always sufficient, condition to induce a residual effect. Because of the possible beneficial residual effect of cover crop burial on erosion reduction, the sowing of a cover crop should be preferred over rough tillage after maize harvest.
Coarse Particulate Matter Emissions from Cattle Feedlots in Australia
Authors: McGinn S. M. , Flesch T. K. , Chen D. , Crenna B. , Denmead O. T. , Naylor T. , Rowell D.
Published: April 2010

Open cattle feedlots are a source of air pollutants that include particular matter (PM). Over 24 h, exposure to ambient concentrations of 50 μg m−3of the coarse‐sized fraction PM (aerodynamic diameter <10 μm [PM10]) is recognized as a health concern for humans. The objective of our study was to document PM10concentration and emissions at two cattle feedlots in Australia over several days in summer. Two automated samplers were used to monitor the background and in‐feedlot PM10concentrations. At the in‐feedlot location, the PM10emission was calculated using a dispersion model. Our measurements revealed that the 24‐h PM10concentrations on some of the days approached or exceeded the health criteria threshold of 50 μg m−3used in Australia. A key factor responsible for the generation of PM10was the increased activity of cattle in the evening that coincided with peak concentrations of PM10(maximum, 792 μg m−3) between 1930 and 2000 h. Rain coincided with a severe decline in PM10concentration and emission. A dispersion model used in our study estimated the emission of PM10between 31 and 60 g animal−1d−1These data contribute to needed information on PM10associated with livestock to develop results‐based environmental policy.
Controls and Rates of Acid Production in Commercial‐Scale Sulfur Blocks
Authors: Birkham T. K. , Hendry M. J. , Barbour S. L. , Lawrence J. R.
Published: April 2010

Acidic drainage (pH 0.4–1.0) from oxidizing elemental sulfur (S0) blocks is an environmental concern in regions where S0 is stockpiled. In this study, the locations, controls, and rates of H2SO4 production in commercial‐scale S0 blocks (∼1–2 × 106 m3) in northern Alberta, Canada, were estimated. In situ modeling of O2 concentrations ([O2]) suggest that 70 to >97% of the annual H2SO4 production occurs in the upper 1 m of the blocks where temperatures increase to >15°C during the summer. Laboratory experiments show that S0 oxidation rates are sensitive to temperature (Q10 = 4.3) and dependent on the activity of autotrophic S0–oxidizing microbes. The annual efflux of SO4 in drainage water from a S0 block (5.5 × 105 kg) was within the estimated range of SO4 production within the block (2.7 × 105 to 1.2 × 106 kg), suggesting that H2SO4 production and removal rates were approximately equal during the study period. The low mean relative humidity within the block (68%; SD = 17%; n = 21) was attributed to osmotic suction from elevated H2SO4 concentrations and suggests a mean in situ pH of approximately −2.1. The low pH of drainage waters was attributed to the mixing of fresh infiltrating water and low‐pH in situ water. Heat generation during S0 oxidation was an important factor in maintaining elevated temperatures (mean, 11.1°C) within the block. The implications of this research are relevant globally because construction methods and the physical properties of S0 blocks are similar worldwide.
Grazing Management Contributions to Net Global Warming Potential: A Long‐term Evaluation in the Northern Great Plains
Authors: Liebig M. A. , Gross J. R. , Kronberg S. L. , Phillips R. L.
Published: April 2010

The role of grassland ecosystems as net sinks or sources of greenhouse gases (GHGs) is limited by a paucity of information regarding management impacts on the flux of nitrous oxide (N2O) and methane (CH4). Furthermore, no long‐term evaluation of net global warming potential (GWP) for grassland ecosystems in the northern Great Plains (NGP) of North America has been reported. Given this need, we sought to determine net GWP for three grazing management systems located within the NGP. Grazing management systems included two native vegetation pastures (moderately grazed pasture [MGP], heavily grazed pasture [HGP]) and a heavily grazed crested wheatgrass [Agropyron desertorum(Fisch. ex. Link) Schult.] pasture (CWP) near Mandan, ND. Factors evaluated for their contribution to GWP included (i) CO2emissions associated with N fertilizer production and application, (ii) literature‐derived estimates of CH4production for enteric fermentation, (iii) change in soil organic carbon (SOC) over 44 yr using archived soil samples, and (iv) soil–atmosphere N2O and CH4fluxes over 3 yr using static chamber methodology. Analysis of SOC indicated all pastures to be significant sinks for SOC, with sequestration rates ranging from 0.39 to 0.46 Mg C ha−1yr−1All pastures were minor sinks for CH4(<2.0 kg CH4–C ha−1yr−1). Greater N inputs within CWP contributed to annual N2O emission nearly threefold greater than HGP and MGP. Due to differences in stocking rate, CH4production from enteric fermentation was nearly threefold less in MGP than CWP and HGP. When factors contributing to net GWP were summed, HGP and MGP were found to serve as net CO2equiv.sinks, while CWP was a net CO2equiv.source. Values for GWP and GHG intensity, however, indicated net reductions in GHG emissions can be most effectively achieved through moderate stocking rates on native vegetation in the NGP.
Source‐Pathway Separation of Multiple Contaminants during a Rainfall‐Runoff Event in an Artificially Drained Agricultural Watershed
Authors: Tomer M. D. , Wilson C. G. , Moorman T. B. , Cole K. J. , Heer D. , Isenhart T.M.
Published: April 2010

A watershed's water quality is influenced by contaminant‐transport pathways unique to each landscape. Accurate information on contaminant‐pathways could provide a basis for mitigation through well‐targeted approaches. This study determined dynamics of nitrate‐N, total P, Escherichia coli, and sediment during a runoff event in Tipton Creek, Iowa. The watershed, under crop and livestock production, has extensive tile drainage discharging through an alluvial valley. A September 2006 storm yielded 5.9 mm of discharge during the ensuing 7 d, which was monitored at the outlet (19,850 ha), two tile‐drainage outfalls (total 1856 ha), and a runoff flume (11 ha) within the sloped valley. Hydrograph separations indicated 13% of tile discharge was from surface intakes. Tile and outlet nitrate‐N loads were similar, verifying subsurface tiles dominate nitrate delivery. On a unit‐area basis, tile total P and E. coli loads, respectively, were about half and 30% of the outlet's; their rapid, synchronous timing showed surface intakes are an important pathway for both contaminants. Flume results indicated field runoff was a significant source of total P and E. coli loads, but not the dominant one. At the outlet, sediment, P, and E. coli were reasonably synchronous. Radionuclide activities of 7Be and 210Pb in suspended sediments showed sheet‐and‐rill erosion sourced only 22% of sediment contributions; therefore, channel sources dominated and were an important source of P and E. coli The contaminants followed unique pathways, necessitating separate mitigation strategies. To comprehensively address water quality, erosion‐control and nitrogen‐management practices currently encouraged could be complemented by buffering surface intakes and stabilizing stream banks.
Impact of Grassed Waterways and Compost Filter Socks on the Quality of Surface Runoff from Corn Fields
Authors: Shipitalo Martin J. , Bonta James V. , Dayton Elizabeth A. , Owens Lloyd B.
Published: April 2010

Surface runoff from cropland frequently has high concentrations of nutrients and herbicides, particularly in the first few events after application. Grassed waterways can control erosion while transmitting this runoff offsite, but are generally ineffective in removing dissolved agrochemicals. In this study, we routed runoff from one tilled (0.67 ha) and one no‐till watershed (0.79 ha) planted to corn (Zea mays L.) into parallel, 30‐m‐long grassed waterways. Two 46‐cm‐diam. filter socks filled with composted bark and wood chips were placed 7.5 m apart in the upper half of one waterway and in the lower half of the other waterway to determine if they decreased concentrations of sediment and dissolved chemicals. Automated samplers were used to obtain samples above and below the treated segments of the waterways for two crop years. The filter socks had no significant effect (P ≤ 0.05) on sediment concentrations for runoff from the no‐till watershed, but contributed to an additional 49% reduction in average sediment concentration compared with unamended waterways used with the tilled watershed. The filter socks significantly increased the concentrations of Cl, NO3–N, PO4–P, SO4, Ca, K, Na, and Mg in runoff from at least one watershed, probably due to soluble forms of these ions in the compost. The estimated additional amounts of these ions contributed by the socks each year ranged from 0.04 to 1.2 kg, thus were likely to be inconsequential. The filter socks contributed to a significant (P ≤ 0.05) additional reduction in dissolved glyphosate [N‐(phosphonomethyl)glycine] (5%) and alachlor [2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxymethyl)acetamide] (18%) concentrations for the tilled watersheds, but this was insufficient to reduce alachlor concentrations to acceptable levels.
Comparison of Natural Humic Substances and Synthetic Ethylenediaminetetraacetic Acid and Nitrilotriacetic Acid as Washing Agents of a Heavy Metal–Polluted Soil
Authors: Soleimani Mohsen , Hajabbasi Mohammad A. , Afyuni Majid , Akbar Samira , Jensen Julie K. , Holm Peter E. , Borggaard Ole K.
Published: April 2010

Ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), and other synthetic polycarboxylic acids have been shown to possess substantial capacity as washing agents of heavy metal–polluted soils, but they are environmentally problematic. Therefore, a sample of natural soluble humic substances (HS) was tested as a possible substitute. The efficiency of HS to extract cadmium (Cd), copper (Cu), and lead (Pb) from a strongly polluted calcareous urban soil was compared with that of EDTA and NTA. The influence of extractant concentration (25–100 mmol L−1 C), solution/soil ratio (5–100 L kg−1), and single‐step vs. multistep extraction on heavy metal removal from the soil was investigated. The extracted pools were assessed by sequential extraction. Ethylenediaminetetraacetic acid and NTA extracted up to 86, 77, and 30% of total soil Cd, Cu, and Pb, respectively, whereas HS extracted 44, 53, and 4%. Extracted amounts of Cd, Cu, and Pb increased with increasing extractant concentration and solution/soil ratio in the range 5 to 100 L kg−1 Single‐step extraction removed about the same amounts of the three metals as multiple‐step extraction. The metal‐extracted pools of the soil depended on the metal and on the extractant. The overall conclusion is that soluble HS can replace synthetic EDTA and NTA as washing agents for Cd‐ and Cu‐polluted soils, whereas HS is not a promising substitute of EDTA or NTA for cleaning Pb‐polluted, calcareous soils.
Attachment of Escherichia coli and Enterococci to Particles in Runoff
Authors: Soupir Michelle L. , Mostaghimi Saied , Dillaha Theo
Published: April 2010

Association of Escherichia coli and enterococci with particulates present in runoff from erodible soils has important implications for modeling the fate and transport of bacteria from agricultural sources and in the selection of management practices to reduce bacterial movement to surface waters. Three soils with different textures were collected from the Ap horizon (silty loam, silty clay loam, and loamy fine sand), placed in portable box plots, treated with standard cowpats, and placed under a rainfall simulator. Rainfall was applied to the plots until saturation‐excess flow occurred for 30 min, and samples were collected 10, 20, and 30 min after initiation of the runoff event. The attachment of E. coli and enterococci to particles present in runoff was determined by a screen filtration and centrifugation procedure. Percentage of E. coli and enterococci attached to particulates in runoff ranged from 28 to 49%, with few statistically significant differences in attachment among the three soils. Similar partitioning release patterns were observed between E. coli and enterococci from the silty loam (r = 0.57) and silty clay loam soils (r = 0.60). At least 60% of all attached E. coli and enterococci were associated particles within an 8‐ to 62‐μm particle size category. The results indicate that the majority of fecal bacteria attach to and are transported with manure colloids in sediment‐laden flow regardless of the soil texture.
Root Growth and Nitrate‐Nitrogen Leaching of Catch Crops following Spring Wheat
Authors: Herrera Juan M. , Feil Boy , Stamp Peter , Liedgens Markus
Published: April 2010

Growing nitrogen (N) catch crops can reduce NO3–N leaching after cultivating cereals. The objective of this study was to relate NO3–N leaching to variation in the uptake of N and the size and distribution of the root systems of different catch crops species. In a 3‐yr lysimeter experiment, phacelia (Phacelia tanacetifolia Benth.), sunflower (Helianthus annuus L.), and a Brassica species (yellow mustard [Brassica alba L.] or a hybrid of turnip rape [B. rapa L. spp. oleifera (DC.) Metzg.] and Chinese cabbage [B. rapa L. ssp. chinensis (L.) Hanelt]) were grown after the harvest of spring wheat under two levels of N supply. Bare soil lysimeters served as the control. Water percolation from the lysimeters and the NO3− concentration in the leachate were measured weekly from the sowing until the presumed frost‐kill of the catch crops. Minirhizotrons were used to assess the spatial and temporal patterns of root growth from 0.10 to 1.00 m. The catch crop species differed in their shoot biomass, N uptake, total NO3–N leaching, and root growth. The results suggested that there was no strict relationship between the total NO3–N leaching of each catch crop species and the N uptake or parameters that indicate static characteristics of the root system. In contrast, the ranking of each catch crop species by parameters that indicate early root growth was inversely related to the ranking of each catch crop species in NO3–N leaching. The rapid establishment of the root system is essential for a catch crop following spring wheat to reduce the amount of NO3–N leaching after the harvest of spring wheat.
Predicting Unsaturated Zone Nitrogen Mass Balances in Agricultural Settings of the United States
Authors: Nolan Bernard T. , Puckett Larry J. , Ma Liwang , Green Christopher T. , Bayless E. Randall , Malone Robert W.
Published: April 2010

Unsaturated zone N fate and transport were evaluated at four sites to identify the predominant pathways of N cycling: an almond [Prunus dulcis (Mill.) D.A. Webb] orchard and cornfield (Zea mays L.) in the lower Merced River study basin, California; and corn–soybean [Glycine max (L.) Merr.] rotations in study basins at Maple Creek, Nebraska, and at Morgan Creek, Maryland. We used inverse modeling with a new version of the Root Zone Water Quality Model (RZWQM2) to estimate soil hydraulic and nitrogen transformation parameters throughout the unsaturated zone; previous versions were limited to 3‐m depth and relied on manual calibration. The overall goal of the modeling was to derive unsaturated zone N mass balances for the four sites. RZWQM2 showed promise for deeper simulation profiles. Relative root mean square error (RRMSE) values for predicted and observed nitrate concentrations in lysimeters were 0.40 and 0.52 for California (6.5 m depth) and Nebraska (10 m), respectively, and index of agreement (d) values were 0.60 and 0.71 (d varies between 0 and 1, with higher values indicating better agreement). For the shallow simulation profile (1 m) in Maryland, RRMSE and d for nitrate were 0.22 and 0.86, respectively. Except for Nebraska, predictions of average nitrate concentration at the bottom of the simulation profile agreed reasonably well with measured concentrations in monitoring wells. The largest additions of N were predicted to come from inorganic fertilizer (153–195 kg N ha−1 yr−1 in California) and N fixation (99 and 131 kg N ha−1 yr−1 in Maryland and Nebraska, respectively). Predicted N losses occurred primarily through plant uptake (144–237 kg N ha−1 yr−1) and deep seepage out of the profile (56–102 kg N ha−1 yr−1). Large reservoirs of organic N (up to 17,500 kg N ha−1 m−1 at Nebraska) were predicted to reside in the unsaturated zone, which has implications for potential future transfer of nitrate to groundwater.
Spectroscopic Models of Soil Organic Carbon in Florida, USA
Authors: Vasques Gustavo M. , Grunwald Sabine , Harris Willie G.
Published: April 2010

Soil organic carbon (SOC) is an indicator of ecosystem quality and plays a major role in the biogeochemical cycles of major nutrients and water. Shortcomings exist to estimate SOC across large regions using rapid and cheap soil sensing approaches. Our objective was to estimate SOC in 7120 mineral and organic soil horizons in Florida using visible/near‐infrared diffuse reflectance spectroscopy (VNIRS) calibrated by committee trees and partial least squares regression (PLSR). The derived VNIRS models were validated using independent datasets and explained up to 71 and 38% of the variance of SOC in mineral and organic horizons, respectively. We stratified the mineral horizons into seven soil orders and derived PLSR models for each order, which explained from 32% (Histosols) to 75% (Ultisols) of the variance of SOC concentration in validation mode. Estimates of SOC from all models were highly scattered along the regression lines, especially for high SOC values, and the slopes of the regression lines were generally <1 because VNIRS models tended to underestimate high SOC values and overestimate low SOC. Despite the great scatter of estimates in the prediction plots, VNIRS models had reasonable explanatory power for mineral horizons, given the heterogeneity of soils and environmental conditions in Florida, and have potential for the rapid assessment of SOC, with implications for regional SOC assessments, modeling, and monitoring. However, VNIRS models for organic horizons were hampered by small sample size and had very limited explanatory power.
Biomass Estimation Approach Impacts on Calculated Soil Organic Carbon Maintenance Requirements and Associated Mineralization Rate Constants
Authors: Clay David , Carlson Gregg , Schumacher Thomas , Owens Vance , Mamani‐Pati Francisco
Published: April 2010

To reduce atmospheric CO2 concentrations and provide food for a growing world population, sustainable management practices must be adopted. An important consideration in the development of sustainable practices is the maintenance of soil organic carbon (SOC). Critical assumptions, with unknown errors, are used to calculate SOC maintenance requirements. This study investigated the impact of three approaches for estimating belowground nonharvested carbon (NHC) on SOC maintenance requirements, SOC and nonharvested C mineralization rate constants, and the capacity of the soil to sequester carbon. Common protocols were used to develop databases from eight historical carbon studies. The SOC to CO2 (kSOC) and NHC to SOC (kNHC) rate constants were calculated using the model NHCa/SOCi = kSOC/kNHC + dSOC/dt(1/kNHCSOCi), where NHCa is the amount of applied NHC, SOCe is SOC at the equilibrium point, t = time, and SOCi is the initial SOC value. Analysis showed that (i) despite the difficulty in measuring belowground biomass, it is needed to calculate the SOC and NHC mineralization rate constants when using nonisotopic approaches; (ii) decreasing NHC by reducing the relative contribution of roots to NHC reduced the calculated SOC maintenance requirements and the amount of corn stover that could be sustainably harvested; iii) changes in the belowground NHC calculation approach do not result in a consistent impact on calculated rate constants; iv) changes in the belowground NHC calculation approach had a minimal impact on the calculated carbon sequestration potential (kNHCNHC)/kSOC; (v) SOC at the beginning of the experiments was negatively correlated with temperature, while kSOC was positively correlated with tillage intensity; and (vi) the kSOC and kNHC rate constants can be used to directly assess the impact of different management scenarios on carbon turnover.
The Adsorption and Release of Sulfur in Mineral and Organic Soils of the Athabasca Oil Sands Region, Alberta, Canada
Authors: Whitfield C. J. , Adkinson A. , Eimers M. C. , Watmough S. A.
Published: April 2010

Mineral soil and fibric peat from acid‐sensitive western boreal catchments in the Athabasca Oil Sands Region of Alberta, Canada were evaluated for their ability to adsorb and release SO42− Laboratory batch studies indicated that SO42− adsorption in mineral soil from both the A and B horizons exhibits a limited response to elevated SO42− concentrations, with the slope of initial mass isotherms <0.2 for all soils, likely due to low iron and aluminum oxide content. Although S retention is the dominant process in peat soils in the region, drought simulations in the lab using fibric peat collected from a poor fen exhibited as much as a five‐fold increase in SO42− concentration after drying and rewetting. Given the limited SO42− adsorption capacity of mineral soils and the potential drought‐induced S release from peatlands in this region where increased S deposition is expected, further investigation of acidification impacts is warranted.
Gas‐Phase Distribution and Emission of Chloropicrin Applied in Gelatin Capsules to Soil Columns
Authors: Wang Qiuxia , Wang Dong , Tang Jueting , Yan Dongdong , Zhang Hongjun , Wang Fangyan , Guo Meixia , Cao Aocheng
Published: April 2010

Chloropicrin (CP) is highly volatile and may pose strong exposure risks for humans and the environment. A gelatin capsule formulation was developed to reduce atmospheric CP emissions and to improve application safety. The objective of this study was to determine the distribution, atmospheric emissions, and soil residual of CP after application in gelatin capsules to soil columns. Two treatments were studied: (i) CP liquid injection with polyethylene film and (ii) CP gelatin capsules with polyethylene film. For the CP liquid injection treatment, the concentration of CP peaked (120.7 μg cm−3) at the 20‐cm depth 1 h after fumigant injection and decreased with time; at other depths, the CP concentration increased initially and decreased after a typical diffusion‐dispersion process. For the gelatin capsule treatment, concentrations of CP at 20 cm depth increased slowly and peaked at 30.04 μg cm−3 264 h after application, indicating a slow CP release through the gelatin capsule shells. The results indicate that a rapid breakdown of gelatin capsules occurred between 11 and 12 d after application. The application of CP gelatin capsules reduced total CP emission by approximately 3 times compared with liquid injection with film cover. Similar residual soil CP was found between the liquid injection and the two gelatin capsule treatments. Chloropicrin gelatin capsules could be a promising new technology for reducing environmental emissions and potential human exposure.
Dissolved and Colloidal Transport of Cesium in Natural Discrete Fractures
Authors: Tang Xiang‐Yu , Weisbrod Noam
Published: April 2010

Transport of cesium (Cs) was investigated in a saturated natural chalk fracture with an average equivalent hydraulic aperture of 129 μm. The results show that Cs (inflow concentration of 0.22 mmol L−1) can be transported in its dissolved form and in association with montmorillonite. Humic acid (HA) did not sorb Cs but enhanced colloid‐associated Cs transport by 12.5% in terms of breakthrough curve (BTC) recovery. The BTCs clearly showed desorption of Cs from the fracture walls during the artificial rainwater (ARW)‐injection period. Cesium transport associated with montmorillonite colloids was significant, with a maximum colloid‐associated Cs C/C0 (outflow‐to‐inflow concentration ratio) value of 16.6 ± 1.1% during the tracer (colloids and LiBr)‐injection period. However, the relative contribution of colloid‐associated Cs transport to total Cs transport was relatively low, amounting to 10.3 ± 0.7% and 14.5 ± 0.7% with montmorillonite (500 mg L−1) and the montmorillonite‐HA (10 mg L−1) mixture, respectively. Readsorption of Cs onto the colloids occurred immediately on switching from the tracer suspension to the background solution of ARW. The significant colloid‐associated Cs transport, the stripping effect of Cs from colloids, and the slow desorption of Cs from fracture walls reported in this study have important implications for risk assessments of Cs mobility in fractured carbonatic rocks.
Using Rare Earth Elements to Control Phosphorus and Track Manure in Runoff
Authors: Buda Anthony R. , Church Clinton , Kleinman Peter J.A. , Saporito Lou S. , Moyer Barton G. , Tao Liang
Published: April 2010

Concern over the enrichment of agricultural runoff with phosphorus (P) from land applied livestock manures has prompted the development of manure amendments that minimize P solubility. In this study, we amended poultry, dairy, and swine manures with two rare earth chlorides, lanthanum chloride (LaCl3·7H2O) and ytterbium chloride (YbCl3·6H2O), to evaluate their effects on P solubility in the manure following incubation in the laboratory as well as on the fate of P and rare earth elements (REEs) when manures were surface‐applied to packed soil boxes and subjected to simulated rainfall. In terms of manure P solubility, La:water‐extractable P (WEP) ratios close to 1:1 resulted in maximum WEP reduction of 95% in dairy manure and 98% in dry poultry litter. Results from the runoff study showed that REE applications to dry manures such as poultry litter were less effective in reducing dissolved reactive phosphorus (DRP) in runoff than in liquid manures and slurries, which was likely due to mixing limitations. The most effective reductions of DRP in runoff by REEs were observed in the alkaline pH soil, although reductions of DRP in runoff from the acidic soil were still >50%. Particulate REEs were strongly associated with particulate P in runoff, suggesting a potentially useful role in tracking the fate of P and other manure constituents from manure‐amended soils. Finally, REEs that remained in soil following runoff had a tendency to precipitate WEP, especially in soils receiving manure amendments. The findings have valuable applications in water quality protection and the evaluation of P site assessment indices.