bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil Test Phosphorus and Clay Content Effects on Runoff Water Quality
Authors: Cox F. R. , Hendricks S. E.
Published: July 2010

Dissolved phosphorus (P) in runoff increases with an increase in soil test P, but slopes found for this relationship vary by an order of magnitude. A difference in clay content contributes to this variation. Experiments were conducted on Ultisols of 5 and 32% clay by incorporating poultry (Gallus gallus domesticus) litter and triple superphosphate (TSP) to create a wide range in Mehlich 3‐extractable phosphorus (M3P). Mehlich 3 P increased similarly for the two sources with rate of P applied, but the increase was greater as clay content decreased. Total P in runoff was measured and it was related primarily to the quantity of sediment. Dissolved P (mg L−1) was measured with simulated rainfall and it increased with an increase in M3P (mg dm−3 in the surface 15–20 cm of soil). The slope of dissolved P versus M3P was 0.0040 for the 5% clay soil and 0.0014 for the 32% clay soil. With these relationships, M3P would need to be 250 mg dm−3 at 5% clay and 714 mg dm−3 at 32% clay to result in 1.0 mg L−1 dissolved P in runoff. Dissolved P in samples of runoff collected from natural rainfall with automatic samplers was substantially less than that with simulated rainfall. Thus, there was a marked difference due to method of measurement as well as the difference noted due to day content. Both factors should be considered if attempting to predict the level of dissolved P in runoff from soil test data.
Modifications of Soil Microbial Activity and Triticonazole Biodegradation by Pesticide Formulation Additives
Authors: Charnay Marie‐Paule , Tarabelli Laetitia , Beigel Claude , Barriuso Enrique
Published: July 2010

Pesticide seed coating represents an example where formulating agents can modify pesticide fate because they are jointly applied in the coating. The influence of additives used to formniate commercial pesticides on degradation in soil of triticonazole [5‐((4‐chlorophenyl) methylene)‐2,2‐dimethyl‐1‐(1H‐1,2,4‐1riazole‐1‐ylmethyl)cyclopentanol] was considered. The studied additives were three different surfactants, one antifoam, one polymer adhesive, and one solvent. Two doses of some formulating additives commonly included in the commercial formulations were used. The individual effects on overall microbial activity and on triticonazole degradation were monitored during laboratory incubations. Total microbial activity was monitored by respirometric measurements and total soil microbial biomass was determined by fumigation‐extraction. The 14C‐triticonazole behavior was characterized by extraction and monitoring of mineralization kinetics. Only the solvent (propylene glycol) and the nonionic micellar surfactant significantly increased the quantities of organic C mineralized. Triticonazole degradation was modified only after the incorporation of formulation additives at high doses (equivalent to 1 g C additive kg−1 soil). The triticonazole degradation increased with the level of available organic C in the case of the solvent, arguing for degradation by a cometabolic pathway. Degradation decreased with the incorporation of the antifoam and the nonionic and anionic (sodiumalkylnaphthalensulfate) surfactants. High concentrations of formulation additives can modify triticonazole behavior in soils, but at the low levels (equivalent to 0.5 g C additive kg−1 soil), degradation data of triticonazole as an active ingredient alone can be used to describe formulated triticonazole behavior.
Predicting Volatile Organic Vapor Sorption from Soil Specific Surface Area and Texture
Authors: Poulsen Tjalfe G. , Yamaguchi Toshiko , Moldrup Per , de Jonge Lis W. , Rolston Dennis E.
Published: July 2010

Vapor sorption of a volatile organic chemical (VOC) to soil minerals at low water contents can increase the total VOC sorption capacity of the soil by several orders of magnitude. Vapor sorption can subsequently cause high VOC fluxes out of the soil during periods with fluctuating low soil water contents. Models for predicting VOC sorption, including vapor sorption, as a function of soil water content are therefore valuable for evaluating contaminant volatilization and exposure risk at polluted sites. A model for estimating trichloroethylene (TCE) surption parameters at low relative vapor pressure from ethylene glycol monoethyl ether (EGME)‐measured soil specific surface area (SA) and soil clay and organic carbon content was developed based on TCE sorption data from 26 different porous media. Significant improvement in prediction accuracy compared with a previous model was achieved. Based on data for 13 soils, an organic carbon partitioning coefficient of Koc, = 0.60 foc cm3 g−1 (R2 = 0.97) for TCE is recommended for use in the new TCE sorption model. In case SA is not available, an expression for predicting SA from soil clay content is proposed. The clay‐based TCE surption model was tested against independent data for two Japanese soils (a sand and a clay loam) measured in this study by a gas chromatography‐based soil microcolumn method. The sorption model accurately predicted TCE retardation (sorption) as a function of soil water content for both soils. Model calibration to sorption data for three different VOC's (benzene, TCE, and toluene) implies that the sorption model may also be applied to chemicals other than TCE. However, sorption measurements for more chemicals and soils at varying water contents are necessary to further generalize the VOC sorption model.
Leaching Rates and Preferential Flow of Selected Herbicides through Tilled and Untilled Soil
Authors: Elliott Jane A. , Cessna Allan J. , Nicholaichuk Wally , Tollefson Laurie C.
Published: July 2010

Pesticides can be transported to ground water more rapidly through preferential flowpaths than would be predicted from their physico‐chemical properties. The leaching rates of the herbicides 2,4‐D, bromoxynil, clopyralid, dicamba, diclofop, MCPA, and mecoprop were compared in this study on plots filled after harvest (conventional till, CT) and those that were not (fall tillage operation omitted, NT). The soil‐incorporated herbicides triallate and trifluralin were applied to the CT plot only. Herbicide was applied immediately prior to a leaching irrigation for salt removal, which represents a “worst‐case” scenario for pesticide leaching. Direct evidence of preferential flow was obtained when the herbicides, with the exception of triallate and trifluralin, were detected in the first water reaching the tile drains. Although the nonincorporated herbicides were transported preferentially at the same rate, the amounts transported depended on the solubility and adsorption coefficient (Koc) of the herbicide. Only 0.01% of the application of the least soluble herbicide, diclofop, was transported, compared with 0.46% of the most soluble herbicide, dicamba. Preferential flow was only slightly reduced by the tillage pass. The amounts of herbicide transported to the tile drain, however, were substantially reduced on the CT plot. The tillage effect was greatest for the more soluble and less strongly absorbed herbicides. There was no clear relationship between amounts transported in the year after application and reported persistence but herbicides with the longer half‐lives persisted in relatively greater amounts than the other herbicides.
Long‐Term Wastewater Treatment Effectiveness of a Northern Wisconsin Peatland
Authors: Nichols Dale S. , Higgins Dale A.
Published: July 2010

Secondary effluent from the Drummond, WI wastewater stabilization lagoon system was applied to an acidic, nutrient‐poor, 8.3‐ha peatland for the purpose of advanced wastewater treatment. Application occurred from June through October at an average rate of 10 cm yr−1 from 1979 to 1982, 24 cm yr−1 from 1983 to 1988, and 40 cm yr−1 from 1989 to 1996, increasing surface flow from the application area by 47, 78, and 154%, respectively. The pH of the peatland outflow increased from 4.2 to 6.7, chloride rose from 1.1 mg L−1 to 80 mg L−1, and total phosphorus increased from 0.05 mg L−1 to 0.6 mg L−1. Because raw sewage input was only one‐half of the lagoon system's design capacity, the lagoons provided a high degree of sewage treatment, removing 95% of suspended solids (SS), biochemical oxygen demand (BOD), and nitrogen from the wastewater stream. Phosphorus removal in the lagoons, which was 98% in the first years of operation, declined to 85% by 1995. The peatland contributed little additional treatment, removing only 37% of the nitrogen and 17% of the phosphorus remaining in the lagoon effluent. The peatland's capacity to retain phosphorus was exhausted after a few years of application. Increased pH, nutrient availability, and water levels altered the peatland vegetation community. The Sphagnum ground cover was reduced or eliminated in many places, and dense stands of cattail (Typha sp.) developed in some areas. Small peatlands such as this one seem poor candidates for use as tertiary treatment systems.
Measurement of the Henry's Constant of Dimethyl Selenide as a Function of Temperature
Authors: Guo Lei , Jury William A. , Frankenberger William T.
Published: July 2010

The Henry's constant (Kh) represents the equilibrium partitioning a gaseous compound between the vapor and liquid phases, and therefore is an important parameter describing the mobility of the compound in soil. Using the method of headspace analysis, we determined the Kh of dimethyl selenide (DMSe) at temperatures ranging from 4 to 40°C. The Kh value was derived by regression analysis of the liquid phase concentration observed at various liquid volumes based on mass balance. The dimensionless Kh of DMSe ranged from 0.032 to 0.135, corresponding to a liquid concentration that is 7 to 31 times higher than the vapor concentration. The nonlinear regression equation describing the dependence of Kh on temperature (T, °C) is Kh = 0.0248exp (0.0418T), indicating that a higher temperature favors partitioning of DMSe to the vapor phase and thus increases transport of DMSe from soil to the atmosphere.
Native Plant Restoration of Copper Mine Tailings: I. Substrate Effect on Growth and Nutritional Status in a Greenhouse Study
Authors: Kramer P. A. , Zabowski D. , Scherer G. , Everett R. L.
Published: July 2010

Copper mine tailings are difficult to revegetate using native plants unless amendments are added to reduce acidity, decrease metal solubility, and improve nutrient availability. In this study, the effects of two amendments were tested for their ability to improve growth and survival of two native plant species growing in copper mine tailings. Unamended tailings from an abandoned copper mine in Washington State were compared with native soil, sandy gravel from local glacial outwash, tailings with a 15‐cm sandy gravel cap, and biosolids with sandy gravel over tailings. Two native plants, Sitka alder [Alnus viridis subsp. sinuata (Regel) A. Love & D. Love] and pearly everlasting [Anaphalis margaritacea (L.) Benth. & Hook. f.], were grown in a greenhouse for 3 to 4 mo in pots of each substrate. Plant biomass was determined and elemental composition of plant tissues were compared among substrates. Survival of both species was 100% in all treatments, but biomass production varied greatly among treatments, with the highest growth in the biosolids and gravel amendment and lowest growth in unamended tailings. Nutrient content varied by species and substrate with high AI concentrations in Sitka alder. Results suggest that N availability is most limiting to pearly everlasting and P is most limiting to Sitka alder. Use of biosolids in conjunction with gravel appears to be an effective tailings amendment.
Long‐Term Plant Community Development on Topsoil Treatments Overlying a Phytotoxic Growth Medium
Authors: Sydnor Russell S. , Redente Edward F.
Published: July 2010

The application of topsoil over phytotoxic mine waste materials is often the most effective method for establishing plant communities and protecting these communities from the inimical properties of such waste materials. However, long‐term data on the effectiveness of this type of remediation, as well as on cultural treatments used to enhance vegetation establishment on topsoil cover treatments, are lacking. Therefore, we evaluated long‐term plant community development on study plots where 60 cm of Paraho retorted oil shale was covered by various depths of topsoil. The study plots were drill seeded with native, introduced, or a combination of native and introduced species, and fertilized with one of three rates of nitrogen (N) and phosphorus (P) fertilizer following construction of the plots in 1977. Data collected 20 yr after seeding showed that total aboveground biomass was greatest on deeper topsoil depths and on plots seeded with introduced plant species. However, when considering the interaction between these two variables, we found that native species were as productive as introduced species on deeper topsoil depths and on the control. Relative plant species composition and plant species richness were greatly influenced by seed mixture treatments. Plots seeded with a particular seed mixture in 1977 were still highly dominated by those species originally seeded, and native seed mixture plots were more species rich than introduced seed mixture plots. Chemical analysis of the soil covers and underlying retorted shale suggests that leaching processes have moderated the once adverse chemical characteristics of the retorted shale.
Interactive Effects of Soil Amendments and Depth of Incorporation on Geyer Willow
Authors: Fisher K. T. , Brummer J. E. , Leininger W. C. , Heil D. M.
Published: July 2010

A greenhouse study was initiated to determine the effect that depth of incorporation of soil amendments had on growth of Geyer willow (Salix geyeriana Andersson) planted in fluvial mine tailing. Lysimeters were constructed to simulate a 60‐cm tailing profile with a static water table established at a depth of 62 cm. The amendment treatments (lime, organic matter, and lime plus organic matter) were each applied at three depths of incorporation (0–20, 0–40, and 0–60 cm). Aboveground current‐year's growth (CYG) from willow cuttings grown in treatments that contained lime was more than eightfold greater than that from willows grown in treatments that did not contain lime. Willows grown in the 0‐ to 60‐cm treatments produced 36% more aboveground CYG than those grown in 0‐ to 20‐cm treatments and 27% more than those grown in the 0‐ to 40‐cm treatments. Belowground CYG, averaged across all amendment treatments, also increased with depth of incorporation. Chemical analyses of the growth media indicated that the lime amendment increased pH of the mine tailing such that trace metals were made less bioavailable and, therefore, not phytotoxic. The addition of organic matter to the lime amendment proved to be beneficial for plant growth and reduced bioavailability of some metals. Willows from all treatments accumulated high concentrations of the metals Cd and Zn in aboveground CYG. Results from this study suggest that increased depth of incorporation of soil amendments into mine tailing can significantly enhance vegetative production of willow cuttings.
Mortality of Escherichia coli O157:H7 in Two Soils with Different Physical and Chemical Properties
Authors: Mubiru D. N. , Coyne M. S. , Grove J. H.
Published: July 2010

Wild and domesticated animals can harbor a pathogenic Escherichia coli strain designated as O157:H7. Potential health problems could occur if strain O157:H7 is a more robust survivor in defecated waste than commonly used indicator bacteria. A laboratory study was conducted to assess E. coli O157:H7 survival relative to a nonpathogenie E. coli strain in two soils with different physical and chemical characteristics. Bacteria in the inoculated soils were enumerated on a weekly basis for 8 wk using a most probable number (MPN) technique. First‐order decay models were used to describe bacteria mortality in the soils. Decay series were described slightly better by a two‐stage function than by a single‐stage function. Strain O157:H7 exhibited similar mortality patterns to the nonpathogenic E. coli in the same soil environment. Both E. coli strains had greater mortality rates in Pope silt loam (coarse‐loamy, mixed, active, mesic Fluventic Dystrudept) than Zanesville silt loam (fine‐silty, mixed, active, mesic Oxyaquic Fragiudalf). Differences in available soil water probably were the overriding factor in E. coli survival. Escherichia coli O157:H7 survival could be modeled in the same way as nonpathogenic E. coli and appears to have a slightly higher mortality rate.
The Relationship of Nitrate Concentrations in Streams to Row Crop Land Use in Iowa
Authors: Schilling Keith E. , Libra Robert D.
Published: July 2010

The relationship between row crop land use and nitrate N concentrations in surface water was evaluated for 15 Iowa watersheds ranging from 1002 to 2774 km2 and 10 smaller watersheds ranging from 47 to 775 km2 for the period 1996 to 1998. The percentage of land in row crop varied from 24 to >87% in the 15 large watersheds, and mean annual NO3‐N concentrations ranged from 0.5 to 10.8 mg/L. In the small watersheds, row crop percentage varied from 28 to 87% and mean annual NO3‐N concentrations ranged from 3.0 to 10.5 mg/L. In both cases, nitrate N concentrations were directly related to the percentage of row crop in the watershed (p < 0.0003). Linear regression showed similar slope for both sets of watersheds (0.11) suggesting that average annual sudace water nitrate concentrations in Iowa, and possibly similar agricultural areas in the midwestern USA, can be approximated by multiplying a watershed's row crop percentage by 0.1. Comparing the Iowa watershed data with similar data collected at a subwatershed scale in Iowa (0.1 to 8.1 km2) and a larger midcontinent scale (7300 to 237 100 km2) suggests that watershed scale affects the relationship of nitrate concentration and land use. The slope of nitrate concentration versus row crop percentage decreases with increasing watershed size.
Evaluation of Diffusion for Inorganic‐Nitrogen Analysis of Natural Water and Wastewater
Authors: Khan S. A. , Mulvaney R. L. , Strle K. , Horgan B. P.
Published: July 2010

Public concern that agricultural use of N fertilizers may have adverse effects on environmental quality and human health has led to a growing need for reliable data concerning the concentration of inorganic N in ground and surface water. A study was conducted to compare the accuracy and precision of simple Mason‐jar diffusion methods for quantitative determination of NH+4 and NO−3, in a wide variety of water and wastewater, relative to colorimetry, ion‐selective potentiometry, and steam distillation. Good agreement among methods was generally obtained with standard solutions prepared using deionized water; however, substantial differences often were observed with natural and anthropogenic samples, because of either Cl− interference in measurements with the NO−3 electrode or CO2−3 interference in distillation. Analytical accuracy also was evaluated by measuring recovery of N added as (NH4)2SO4 or KNO3, (6 mg N L−1). With most of the samples studied, quantitative recovery (97–103%) was not achieved by potentiometry or distillation. Quantitative recoveries usually were achieved by a manual Berthelot method for colorimetric determination of NH+4, whereas recovery was often incomplete when NO−3 analyses were performed with an automated flow‐injection system using Cd2+ reduction. Regardless of the sample matrix, diffusion was always accurate in measuring recovery of NH+4 or NO−3.
Denitrification in an Estuarine Headwater Creek within an Agricultural Watershed
Authors: Thompson Suzanne P. , Piehler Michael F. , Paerl Hans W.
Published: July 2010

Nonpoint agricultural surface water runoff has been identified as a significant contributor to watershed nitrogen (N) loading. Denitrification is thought to be a substantial sink for N inputs to estuaries. Denitrification rates and inorganic N concentrations were measured in Culvert Creek, NC for a 3‐yr period with an adaptation of the acetylene block technique using saturation kinetic incubations that provided estimated in situ and potential rates. Estimated in situ denitrification and inorganic N concentrations were elevated in portions of Culvert Creek, NC following fertilizer application at adjacent Open Grounds Farm. Statistical correlations indicated that denitrification in Culvert Creek was regulated by inorganic N, paticularly at headwater sites. Regulation was complex at estuarine sites, where dynamic hydrological conditions affected microbial processing of N through coupled nitrification‐denitrification. Potential denitrification rates were often an order of magnitude higher than estimated in situ rates. Potential denitrification showed a similar seasonal‐spatial pattern to that of nitrification at the most estuarine site, with lower rates at the mid‐creek sites where nitrification was inhibited during periods of anoxia. Annual N removal in Culvert Creek was estimated at 1.27% (in situ) or 68.70% (potential rates) of inputs. An estimated 11% of N inputs were removed via the nitrification‐denitrification pathway in Culvert Creek assuming that rates were closely coupled. Mean annual (1995–1997) creek denitrification rates of 2.17 kg N ha−1 yr−1 (in situ) and 90.52 kg N ha−1 yr−1 (potential) were within the range of rates measured in various freshwater wetland systems receiving agricultural drainage. In Culvert Creek, denitrification was a significant mediator of estuarine headwater N cycling.
Phosphorus Reactions and Leaching Potential in Soils Amended with Sewage Sludge
Authors: Siddique Muhammad Tariq , Robinson J. Stephen , Alloway Brian J.
Published: July 2010

The objective of this study was to evaluate the leaching potential of P from a range of sewage sludge‐ or P fertilizer (monocalcium phosphate)‐amended topsoils that had different P contents. Leaching trials (70 d) were conducted in 30‐cm‐long PVC columns; P‐related parameters were then determined at different depths in the leached soils. In most cases, more (P < 0.01) P was released from the P‐fertilized than sludge‐treated soils. Increasing native Olsen P from 15 to 62 mg kg−1 had negligible effect on P release; however, there was a sharp increase in P leached between 92 and 134 (maximum) mg Olsen P kg−1. This increase was much greater in the P‐fertilized than sludge‐treated soils. At all depths in all leached soils, resin P decreased in the order: P fertilized > sludge > control. At the lowest depth (16–20 cm) of the leached soil, the degree of P sorption saturation decreased in the same order and was related curvilinearly (P < 0.001) to cumulative P leached (at 70 d). This relationship demonstrates the importance of P sorption saturation in controlling P leaching in sludge‐ and fertilizer‐treated soils. The more rapid rate of P saturation and P leaching in P‐fertilized than sludge‐treated soils emphasizes the role of the P source in adsorption‐desorption processes.
Effect of Sodium Hydroxide Addition on Polycyclic Aromatic Hydrocarbon Emissions of Toluene Flames
Authors: Wei Yu‐Ling
Published: July 2010

Addition of sodium hydroxide solution into organic flames has been extensively investigated to reduce soot formation; nevertheless, data on the effect of metal salt solution on the formation of hazardous air pollutants of polycyclic aromatic hydrocarbons (PAHs) are rather scarce. A laboratory‐scale liquid‐injection incinerator was used to incinerate toluene, which resembled a waste or used solvent. Solid‐phase and gas‐phase PAHs in the flue gases were sampled, treated, and analyzed using a high performance liquid chromatograph (HPLC). The experimental parameters included equivalence ratio and concentration of added sodium hydroxide solution. The incineration temperature was 750°C and the nominal gas residence time was approximately 2.5 s. Results indicated that particles might play a very active role in the formation of PAHs under all experimental conditions. Further, under oxygen‐rich incineration, addition of sodium hydroxide solution caused a considerable increase of the sixteen solid‐phase priority pollutant PAHs (pp‐PAHs); while for oxygen‐lean toluene flame the effect of addition of NaOH solution on solid‐phase PAH was only slight. This greater solid‐phase PAH content on soot of the oxygen‐rich NaOH‐seeded toluene flames suggested that the radical catalysis cycle of NaOH to NaO2 to Na to NaO, then back to NaOH (Zamansky et al., 1999) might have affected the solid‐phase PAH measurements. We speculate that hydrogen atoms were abstracted from hydrocarbons to form H2O and 16 pp‐PAHs by OH radicals that were produced via the sodium catalysis cycle.
Evaluating Soil Tests to Predict Bermudagrass Growth in Drinking Water Treatment Residuals with Phosphorus Fertilizer
Authors: Basta N. T. , Zupancic R. J. , Dayton E. A.
Published: July 2010

Drinking water treatment residuals (WTRs) may serve as a soil substitute to revegetate disturbed land. This study evaluated the use of WTRs as a soil substitute and the ability of soil tests to predict P adequacy. We measured properties and nutrient content of three WTRs (Wister, Mohawk, and ABJ) and a control soil. Bermudagrass [Cynodon dactylon (L.) Pers. var. Greenfield] was grown with four P treatments (0, 50, 100, and 200 mg P kg−1). We measured available P by water, Mehlich 3 (M3P), and Olsen P soil extraction. Mean cumulative bermudagrass yields, across P treatments, were soil (20.6 g), Mohawk (23.6 g) > Wister (9.6 g) > ABJ (1.1 g). Tissue P concentrations were below adequate for WTR and available P in WTR was deficient for Wister and ABJ. Fertilizer P addition did not increase yield or tissue P of bermudagrass grown on WTR. However, bermudagrass grown on soil had increased yield and tissue P with fertilizer addition. The available P measured by soil tests was adequate for Mohawk and inadequate for ABJ, Wister, and soil. Although the M3P and OIsen P soil tests predicted P responses on some WTRs, with fertilizer addition, there was not a yield or tissue response. Water soluble P or Olsen P provide information on the ability of the WTR to support growth but not the ability to predict P adequacy. The M3P soil test overestimated plant availability of P in WTR due to the dissolution of P adsorbed by amorphous Al. Water extracts were the best predictor of P adequacy in WTR and should be used to determine P fertilizer additions to WTR.
Loss of Bromide in a Wetland Tracer Experiment
Authors: Whitmer Shawn , Baker Larry , Wass Roland
Published: July 2010

Bromide recovery during tracer tests conducted in 12 wetland research cells averaged 48%. Loss of water by infiltration, analytical biases, and inadequate measurement period were rejected as causes of low bromide recovery. The nonconservative behavior of bromide was probably caused by plant uptake. Investigators conducting bromide tracer studies in wetlands should recognize that bromide may be not be conservative in wetlands, particularly during periods of rapid plant growth.
Cadmium Tolerance and Accumulation in Cultivars of a High‐Biomass Tropical Tree (Averrhoa carambola) and Its Potential for Phytoextraction
Authors: Li J. T. , Liao B. , Lan C. Y. , Ye Z. H. , Baker A. J. M. , Shu W. S.
Published: July 2010

Averrhoa carambola is a high‐biomass tropical tree that has been identified as a Cd accumulator. In the present study, field survey, pot, and hydroponic experiments were conducted to investigate the variation of Cd tolerance and accumulation in cultivars of A. carambola as well as its potential for phytoextraction. In the field survey, it was found that concentrations of Cd in aerial tissues of A. carambola varied greatly among sites and cultivars. The Cd bioconcentration factors (BCFs) and Cd removals by the field‐grown A. carambola differed significantly among sites but not among cultivars. Nonetheless, all four carambola cultivars investigated were able to accumulate considerably high concentrations of Cd in their shoots, which indicated that the 4‐yr‐old carambola stands could remove 0.3 to 51.8% of the total Cd content in the top 20‐cm soil layer. When cultured in Cd‐spiked soils, the carambola cultivar Hua‐Di always showed higher Cd tolerance than the other cultivars; however, this tendency was not confirmed by hydroponic experiment. The Cd BCFs of cultivar Thailand grown in soils with 6 and 12 mg Cd kg−1 were highest among cultivars, whereas this trend was reversed at 120 mg Cd kg−1 treatment. Nevertheless, the pot‐ and hydroponics‐grown carambola cultivars generally showed higher capacities to tolerate and accumulate Cd, compared with the control species. The present results indicate that a strong ability to tolerate and accumulate Cd seems to be a trait at the species level in A. carambola, although some degree of variances in both Cd tolerance and accumulation exists among cultivars.
Increasing Precision of Turbidity‐Based Suspended Sediment Concentration and Load Estimates
Authors: Jastram John D. , Zipper Carl E. , Zelazny Lucian W. , Hyer Kenneth E.
Published: July 2010

Turbidity is an effective tool for estimating and monitoring suspended sediments in aquatic systems. Turbidity can be measured in situ remotely and at fine temporal scales as a surrogate for suspended sediment concentration (SSC), providing opportunity for a more complete record of SSC than is possible with physical sampling approaches. However, there is variability in turbidity‐based SSC estimates and in sediment loadings calculated from those estimates. This study investigated the potential to improve turbidity‐based SSC, and by extension the resulting sediment loading estimates, by incorporating hydrologic variables that can be monitored remotely and continuously (typically 15‐min intervals) into the SSC estimation procedure. On the Roanoke River in southwestern Virginia, hydrologic stage, turbidity, and other water‐quality parameters were monitored with in situ instrumentation; suspended sediments were sampled manually during elevated turbidity events; samples were analyzed for SSC and physical properties including particle‐size distribution and organic C content; and rainfall was quantified by geologic source area. The study identified physical properties of the suspended‐sediment samples that contribute to SSC estimation variance and hydrologic variables that explained variability of those physical properties. Results indicated that the inclusion of any of the measured physical properties in turbidity‐based SSC estimation models reduces unexplained variance. Further, the use of hydrologic variables to represent these physical properties, along with turbidity, resulted in a model, relying solely on data collected remotely and continuously, that estimated SSC with less variance than a conventional turbidity‐based univariate model, allowing a more precise estimate of sediment loading. Modeling results are consistent with known mechanisms governing sediment transport in hydrologic systems.
Reducing Nitrogen Loss during Poultry Litter Composting Using Biochar
Authors: Steiner Christoph , Das K.C. , Melear Nathan , Lakly Donald
Published: July 2010

Poultry litter (PL) is a potentially underused fertilizer because it contains appreciable amounts of N, P, K, and micronutrients. However, treatments like composting to reduce potential pathogens, weed seeds, and odor often result in high losses of N through NH3 volatilization. Biochar (BC) has been shown to act as an absorber of NH3 and water‐soluble NH4+ and might therefore reduce losses of N during composting of manure. We produced three PL compost mixtures that consisted of PL without added BC (BC0), PL + 5% BC (BC5), and PL + 20% BC (BC20). The BC was produced from pine chips and used without further modifications. Three replicates of each treatment were placed in nine bioreactors to undergo composting for 42 d. The entire composting experiment was repeated three times in a complete‐block design. Moisture content, temperature, pH, mass loss, gas (NH3, CO2, H2S) emissions, C, and nutrient contents were measured periodically throughout the experiments. Results showed no difference in PL mass loss with BC addition. Moisture content decreased, pH increased significantly, and peak CO2 and temperatures were significantly higher with BC20 compared with BC0. These results indicate a faster decomposition of PL if amended with BC. Ammonia concentrations in the emissions were lower by up to 64% if PL was mixed with BC (BC20), and total N losses were reduced by up to 52%. Biochar might be an ideal bulking agent for composting N‐rich materials.
Dissipation of Sulfamethazine and Tetracycline in the Root Zone of Grass and Tree Species
Authors: Lin Chung‐Ho , Goyne Keith W. , Kremer Robert J. , Lerch Robert N. , Garrett Harold E.
Published: July 2010

The detection of veterinary antibiotics (VAs) in drinking water resources resulting from manure disposal operations has raised public health concerns. Previous studies have demonstrated the benefits of using multispecies vegetated buffer strips (VBS) to reduce agrichemical transport from agroecosystems. However, VA fate and subsequent effects of VAs on microbial activities in the root zone of VBS have not been well documented. A growth chamber study was conducted to investigate dissipation of two commonly administered VAs, sulfamethazine (SMZ) and tetracycline (TC), and the relationship between VA dissipation and soil enzyme activities in the root zone of selected plant species. Switchgrass, eastern gammagrass, orchardgrass, and a hybrid poplar tree were grown in pots containing a Mexico silt loam/sand mixture for 3 mo, followed by plant biomass removal and collection of root zone soil. Radiolabeled (3H) SMZ or TC was applied to the soils and samples were incubated in the dark for 5 wk. Among the plant species studied, hybrid poplar showed enhanced capability for promoting SMZ dissipation. The half‐lives of SMZ in soil planted to the poplar tree were significantly reduced by the enhanced enzymatic activity. Comparison of soil enzymatic activities between the antibiotic treatments revealed that fluorescein diacetate hydrolytic and glucosaminidase enzyme activities were significantly lower in TC‐treated soils than in SMZ‐treated soils. The β‐glucosidase activities were similar between the two VA treatments. Correlation analyses showed that the half‐life of SMZ in the soil was negatively correlated with enzymatic activity. Enhanced SMZ dissipation in soil planted to hybrid poplar suggests that incorporation of this plant species in VBS may mitigate deleterious effects of SMZ in the environment.
Soil Phosphorus Forms in Hydrologically Isolated Wetlands and Surrounding Pasture Uplands
Authors: Cheesman Alexander W. , Dunne Ed J. , Turner Benjamin L. , Reddy K. Ramesh
Published: July 2010

Newly created and restored wetlands play an important role in sequestering excess nutrients at the landscape scale. In evaluating the long‐term efficacy of nutrient management strategies to increase wetland capacity for sequestering P, information is needed on the forms of P found across the upland–wetland transition. To assess this, we studied soils (0–10 cm) from four wetlands within cow–calf pastures north of Lake Okeechobee, FL. Wetlands contained significantly (P< 0.05) greater concentrations of organic matter (219 g C kg−1), total P (371 mg P kg−1), and metals (Al, Fe) relative to surrounding pasture. When calculated on an aerial basis, wetland surface soils contained significantly greater amounts of total P (236 kg ha−1) compared with upland soils (114 kg ha−1), which was linked to the concomitant increase in organic matter with increasing hydroperiod. The concentration of P forms, determined by extraction with anion exchange membranes, 1 mol L−1HCl, and an alkaline extract (0.25 mol L−1NaOH and 50 mmol L−1ethylenediaminetetraacetic acid [EDTA]) showed significant differences between uplands and wetlands but did not alter as a proportion of total P. Speciation of NaOH–EDTA extracts by solution31P nuclear magnetic resonance spectroscopy revealed that organic P was dominated by phosphomonoesters in both wetland and pasture soils but thatmyo‐inositol hexakisphosphate was not detected in any sample. The tight coupling of total C and P in the sandy soils of the region suggests that the successful management of historically isolated wetlands for P sequestration depends on the long‐term accumulation and stabilization of soil organic matter.
Modeling Nutrient Flows in the Food Chain of China
Authors: Ma L. , Ma W. Q. , Velthof G. L. , Wang F. H. , Qin W. , Zhang F. S. , Oenema O.
Published: July 2010

Increasing nitrogen (N) and phosphorus (P) inputs have greatly contributed to the increasing food production in China during the last decades, but have also increased N and P losses to the environment. The pathways and magnitude of these losses are not well quantified. Here, we report on N and P use efficiencies and losses at a national scale in 2005, using the model NUFER (NUtrient flows in Food chains, Environment and Resources use). Total amount of “new” N imported to the food chain was 48.8 Tg in 2005. Only 4.4.Tg reached households as food. Average N use efficiencies in crop production, animal production, and the whole food chain were 26, 11, and 9%, respectively. Most of the imported N was lost to the environment, that is, 23 Tg N to atmosphere, as ammonia (57%), nitrous oxide (2%), dinitrogen (33%), and nitrogen oxides (8%), and 20 Tg to waters. The total P input into the food chain was 7.8 Tg. The average P use efficiencies in crop production, animal production, and the whole food chain were 36, 5, and 7%, respectively. This is the first comprehensive overview of N and P balances, losses, and use efficiencies of the food chain in China. It shows that the N and P costs of food are high (for N 11 kg kg−1, for P 13 kg kg−1). Key measures for lowering the N and P costs of food production are (i) increasing crop and animal production, (ii) balanced fertilization, and (iii) improved manure management.
Predicting Water Quality in Unmonitored Watersheds Using Artificial Neural Networks
Authors: Kalin Latif , Isik Sabahattin , Schoonover Jon E. , Lockaby B. Graeme
Published: July 2010

Land use and land cover (LULC) play a central role in fate and transport of water quality (WQ) parameters in watersheds. Developing relationships between LULC and WQ parameters is essential for evaluating the quality of water resources. In this paper, we present an artificial neural network (ANN)–based methodology to predict WQ parameters in watersheds with no prior WQ data. The model relies on LULC percentages, temperature, and stream discharge as inputs. The approach is applied to 18 watersheds in west Georgia, United States, having a LULC gradient and varying in size from 2.96 to 26.59 km2 Out of 18 watersheds, 12 were used for training, 3 for validation, and 3 for testing the ANN model. The WQ parameters tested are total dissolved solids (TDS), total suspended solids (TSS), chlorine (Cl), nitrate (NO3), sulfate (SO4), sodium (Na), potassium (K), total phosphorus (TP), and dissolved organic carbon (DOC). Model performances are evaluated on the basis of a performance rating system whereby performances are categorized as unsatisfactory, satisfactory, good, or very good. Overall, the ANN models developed using the training data performed quite well in the independent test watersheds. Based on the rating system TDS, Cl, NO3, SO4, Na, K, and DOC had a performance of at least “good” in all three test watersheds. The average performance for TSS and TP in the three test watersheds were “good.” Overall the model performed better in the pastoral and forested watersheds with an average rating of “very good.” The average model performance at the urban watershed was “good.” This study showed that if WQ and LULC data are available from multiple watersheds in an area with relatively similar physiographic properties, then one can successfully predict the impact of LULC changes on WQ in any nearby watershed.
Manure Odor Potential and Escherichia coli Concentrations in Manure Slurries of Feedlot Steers Fed 40% Corn Wet Distillers Grains
Authors: Varel Vincent H. , Wells James E. , Berry Elaine D. , Miller Dan N.
Published: July 2010

This study evaluated feeding 0 and 40% wet distillers grains with solubles (WDGS) diets to cattle and the effects on feedlot manure collected from soil‐based pens and incubated for 28 d. Steers (n = 603; 261 ± 32 kg) were fed in eight pens (15 × 150 m) of 75 to 77 steers per pen. Two consecutive experiments were conducted with WDGS—one in which the corn source fed with WDGS was high‐moisture and one in which WDGS was fed with dry‐rolled corn. We compared odorants (volatile fatty acids [VFAs], aromatic compounds, NH3, H2S) and persistence of Escherichia coli in feedlot manure slurries stored from 0 to 28 d. From both experiments, manure collected from cattle fed 40% WDGS had lower (P < 0.05) total VFAs, including acetate, propionate, and butyrate, all of which continued to be lower to 28 d. However, these slurries had greater concentrations (P < 0.05) of branched‐chained VFAs (isobutyrate and isovalerate), especially after 14 d of incubations. Similarly, p‐cresol and skatole concentrations tended to be greater in slurries originating from 40% WDGS diets and increased with incubation time. Indole was initially greater in the slurries from 40% WDGS diets; however, it was metabolized by microbes during incubation. Manure slurries from the 40% WDGS diets had greater quantities of H2S, NH3, and P (P < 0.05). Levels of E. coli in 0 and 40% WDGS manure slurries were similar when high‐moisture corn was used in the diets. However, when dry‐rolled corn was used, E. coli persisted longer in 40% WDGS manure slurries in comparison to 0% WDGS. Results here support earlier studies that suggest feeding WDGS increases odor emissions, N loss, E. coli survival, and surface water contamination due to greater potential P runoff.
Denitrification: An Important Pathway for Nitrous Oxide Production in Tropical Mangrove Sediments (Goa, India)
Authors: Fernandes Sheryl Oliveira , Bharathi P.A. Loka , Bonin Patricia C. , Michotey Valérie D.
Published: July 2010

Net nitrous oxide production and denitrification activity were measured in two mangrove ecosystems of Goa, India. The relatively pristine site Tuvem was compared to Divar, which is prone to high nutrient input. Stratified sampling at 2‐cm intervals within the 0‐ to 10‐cm depth range showed that N2O production at both the locations decreased with depth. Elevated denitrification activity at Divar resulted in maximum production of up to 1.95 nmol N2O‐N g−1h−1at 2 to 4 cm, which was three times higher than at Tuvem. Detailed investigations to understand the major pathway contributing to N2O production performed at Tuvem showed that incomplete denitrification was responsible for up to 43 to 93% of N2O production. Nitrous oxide production rates closely correlated to nitrite concentration (n= 15;r= −0.47;p< 0.05) and denitrifier abundance (r= 0.55;p< 0.05), suggesting that nitrite utilization by microbial activity leads to N2O production. Nitrous oxide production through nitrification was below detection, affirming that denitrification is the major pathway responsible for production of the greenhouse gas. Net N2O production in these mangrove systems are comparatively higher than those reported from other natural estuarine sediments and therefore warrant mitigation measures.
Influence of Free Stream Turbulence Intensity on Heat Transfer and Flow Around Four In-Line Elliptic Cylinders in Cross Flow
Authors: Sakr Ramadan Y. , Berbish Nabil M. , Abd-Aziz Ali A.
Published: July 2010

The effect of free stream turbulence intensity on heat transfer and flow characteristics around four in-line elliptic cylinders in cross flow was experimentally and numerically investigated. The elliptic cylinders examined had an axis ratio (b/c) of (1:3) with a zero angle of attack (where the major axis is horizontal) and were heated under a constant heat flux condition. Three different sizes of free stream turbulence producing grids (screen) inserted at a distance of 300 mm the upstream test cylinders are used to study the effect of the free stream turbulence. The turbulence intensity levels of 5.6%, 8.3% and 10.5% are obtained from the grid sizes. The effects of cylinder spacing ratio (L/c) were examined within Reynolds number (based on free stream velocity and major axis length) ranging from 3640 to 66240. It was observed that the local and average Nusselt numbers of the tested elliptic cylinders increase with increasing the free stream turbulence intensity. The results showed that the maximum enhancement ratio for the average Nusselt number (for the tested cylinder with grid and for the single elliptic cylinder without grid) was found to be about 1.93 and was obtained for the second elliptic cylinder in four in-line cylinders at L/c=1.5, Re=6150 with free stream turbulence intensity of 10.5%. Also, the flow characteristics varied drastically with both the longitudinal spacing ratio and the inserted grid (screen). Moreover, an empirical correlation for the average Nusselt number of the second elliptic cylinder of the four in-line cylinders was obtained as function of Reynolds number and free stream turbulence intensity.
Agglomeration of Bitumen-Coated Coke Particles in Fluid Cokers
Authors: Darabi Pirooz , Pougatch Konstantin , Salcudean Martha , Grecov Dana
Published: July 2010

A simplified mathematical model is proposed to determine the agglomeration tendency of bitumen-coated coke particles in fluid cokers. The model calculates a theoretical critical velocity that depends on key parameters such as the particle size, bitumen viscosity, and bitumen thickness; it also accounts for the temperature- and reaction-dependent variations of the bitumen thickness and viscosity. A peak theoretical critical velocity at the intermediate reaction times for all coking temperatures is predicted. By comparing this peak critical velocity with the estimated inter-particle collision velocities within an industrial-scale reactor, the agglomeration tendency of coke particles is determined within fluid cokers. The results show that at low temperature regions (T=400 °C), there is no agglomeration tendency; however, at high coking temperatures (T=503 and 530 °C), substantial agglomeration tendency is expected. It is also found that the number of coke particles constituting an agglomerate could be as high as a few hundreds.
Experimental Estimation of Fluidization Parameters - A Stochastic Approximation Method Approach
Authors: Yakubov Bachtiyar M. , Yakubov Eduard , Gotlib Victor A.
Published: July 2010

The paper deals with the use of the stochastic approximation method for estimation parameters of the fluidization process and detecting a change of the process mode based on experimental photographs of local part. The fluidization process is treated as a process of diffusion type, described by the diffusive equation. Because the solid particles are essentially discrete ones and the moments of process observation are also discrete, the diffusive equation is treated in the difference form. The problem of modeling of the fluidized bed is reduced to the estimation of coefficients of difference equations system. The method of stochastic approximation is used for this estimation. The method allows identifying the regime of the fluidization process in its dynamics and estimating the parameters of the process. The approach and the estimating algorithm were verified using the especial experiments.