bluuebunny/crossref_metadata_2025 huggingface dataset:
Volatilization of Methyl Isothiocyanate from Soil after Application of Metam‐Sodium with Two Techniques
Authors: van den Berg F. , Smelt J. H. , Boesten J. J. T. I , Teunissen W.
Published: July 2010

The large‐scale use of soil fumigants results in substantial emissions into the air. To describe the fate of these chemicals in soil, the PEST‐icide Leaching and Accumulation (PESTLA) model was extended to include the diffusion of pesticides through the gas phase and their volatilization at the soil surface. The model was tested against measurements of methyl isothiocyanate after injection of metam‐sodium into the soil at 0.19‐m depth with a blade injector and after injection at 0.10‐m depth followed by rototillage. For both techniques, the fumigant behavior in soil was described reasonably well. The volatilization rates measured in the field corresponded roughly to the rates computed. After injection with the blade injector at 0.19‐m depth, the initial volatilization rates measured were higher than those computed. This is possibly the result of rapid diffusion of fumigant through large voids in the topsoil. Such heterogeneities were not accounted for in the model. For shallow injection followed by rototillage, the volatilization rates were high from the start, both in the computations and measurements. The cumulative volatilization of methyl isothiocyanate when injecting metam‐sodium at 0.19‐m depth was computed to range up to a few percent of the dosage. When shallow injection was followed by rototillage, the computed cumulative emission ranged between 17 and 34% of the dosage. The model can be used to evaluate the effect of different factors on the volatilization of fumigants and that of other, soil‐incorporated pesticides from homogeneous noncracking soils, but for the evaluation of tillage factors model development is needed.
Sorption of Chlorobiphenyls in Sediment—Water Systems Containing Nonionic Surfactants
Authors: Park Jae‐Woo , Boyd Stephen A.
Published: July 2010

Nonionic surfactants may aid remediation of contaminated soils and sediments by increasing aqueous concentrations of poorly water‐soluble organic contaminants. In order to explore the effects of nonionic surfactants on the sediment—water distribution of PCBs, a series of batch experiments was performed using four commercial nonionic surfactants (Triton X‐100, Triton X‐405, Triton X‐705, and Tween 80) and Red Cedar River sediment. Sediment—water distributions of 4,4′‐dichlorobiphenyl (Di‐CB), 2,2′,4,4′‐tetrachlorobiphenyl (Tetra‐CB), and 2,2′,4,4′,5,5′‐hexachlorobiphenyl (Hexa‐CB) were studied at aqueous surfactant concentrations ranging from zero to >1.5 times the critical micelle concentration (CMC) of each surfactant. The results show decreases in apparent soil—water distribution coefficients (K*) of PCB congeners at all surfactant concentrations as compared to the intrinsic sorption coefficient (K) in the absence of surfactant, unlike that previously reported. A new model incorporating a surface micellization concept for the sorbed surfactant phase was successfully applied to experimental data presented here and in a previous study.
Ground Water Nitrate Removal in Subsoil of Forested and Mowed Riparian Buffer Zones
Authors: Addy K. L. , Gold A. J. , Groffman P. M. , Jacinthe P. A.
Published: July 2010

We studied two similar riparian sites in southern New England and examined ground water nitrate (NO−3‐N) removal in the subsurface of mowed (i.e., herbaceous) vs. forested (i.e., woody) vegetation. Each site consisted of poorly drained, fine to medium sands and contained adjacent areas of mowed and forested vegetation. We dosed mesocosms with bromide and 15N labeled NO−3‐N amended ground water to simulate the shallow ground water NO−3‐N dynamics of riparian buffer zones. Mesocosms were composed of undisturbed, horizontal soil cores (40 cm long, 15 cm diam.) extracted from seasonally saturated subsoil We observed substantial ground water NO−3‐N removal and denitrification at all locations. Ground water NO−3‐N removal rates were significantly correlated with carbon‐enriched patches of organic matter. This correlation supports previous work that patches function as hotspots of microbial activity in the subsoil. Within each site, we found no significant difference in ground water NO−3‐N removal rates in the subsoil of forested and mowed areas and we noted tree roots throughout the subsoil of the mowed areas. We found that ground water NO3‐N removal rates differed significantly between similar sites. We caution against ascribing specific ground water NO−3‐N removal rates to different riparian aboveground vegetation types without recognizing the importance of site differences, e.g., water table dynamics, land use legacy and adjacent vegetation. Riparian zones composed of a mix of forested and mowed vegetation, common in agroforestry and suburban land uses, may remove substantial amounts of ground water NO−3‐N.
Predicting Nitrate Leaching from Drained Arable Soils Derived from Glacial Till
Authors: Vinten A. J. A.
Published: July 2010

Regional‐scale prediction of ground and surface water pollution by nitrate (NO3) requires field‐scale prediction of NO3 leaching. This can be done by a N balance sheet approach, but this is not robust, because no account is taken of organic matter dynamics or denitrification. In this paper, predictions of NO3 leaching made using a balance sheet method and those using a dynamic N cycle model, Agricultural Nitrogen Model (ANIMO), are compared with observations of NO3 leaching from drained plot experiments on two Scottish arable soils, a clay loam (aquic Haplaquept) and a sandy loam (dystric Eutrochrept). Mineral N fertilizer applications in these experiments varied from 0 to 210 kg N ha−1 and the mean observed NO3‐N leaching to drains was 21 kg N ha−1 for the clay loam and 53 kg N ha−1 for the sandy loam. The balance sheet method on average overpredicted NO3 leaching by 120% for the clay loam and underpredicted by 16% for the sandy loam. ANIMO predictions using default parameters were poor but when subsoil respiration was included to a depth of 0.7 m at the clay loam site and 2.0 m at the sandy loam site, the mean predicted NO3‐N leaching was within 2% of observed. The root mean square error was still quite large (76 and 53% for the clay loam and sandy loam, respectively) and the correlation coefficient was poor at the clay loam site (r = 0.09 and 0.91 for the clay loam and sandy loam, respectively). Simulated denitrification losses are strongly dependent on the depth to which soil respiration occurs. Work is needed to obtain more direct evidence of subsoil denitrification. Heterogeneity of topsoil organic matter and respiration may also need to be taken into account.
Using Granulated Wood Charcoal as a Filter Medium
Authors: Agbanobi R. O.
Published: July 2010

The use of activated carbon (AC) filtration and chlorination to polish wastewater effluent is becoming increasingly costly. A cost‐effective approach is needed to clean large volumes of wastewater often discharged into surface waters or used to recharge depleted ground water aquifers. Hardwood charcoal is characterized by large pore size, which makes it a possible media for absorbing bacteria and organic matter, similar to AC in filtration capabilities. To determine the efficiency of granular wood charcoal (GWC) as a filter medium, a comparative study was carried out in a laboratory test using GWC and sand. The results showed that GWC is superior to the sand in pollutant removal and length of effectiveness. This is important because GWC can be obtained at relatively little cost. This is an effective and environmentally sound approach for recycling the growing volume of wood charcoal in the municipal solid waste stream.
Enzyme and Earthworm Activities during Vermicomposting of Carbaryl‐Treated Sewage Sludge
Authors: Benitez E. , Nogales R. , Elvira C. , Masciandaro G. , Ceccanti B.
Published: July 2010

The feasibility of vermicomposting pesticide contaminated refuses was evaluated. A mixture of sewage sludges was amended, at a ratio of 1:1 (v/v), with a garden refuse artificially contaminated with carbaryl, a carbamate insecticide commonly used in farming and gardening. Ten clitellated earthworms were then placed in this material. We determined the evolution of earthworm (Eisenia foetida, Savigny) biomass and changes in enzyme activities during an 18‐wk period of sewage sludge vermicomposting. The carbaryl produced a chronically toxic effect on the earthworms, measured by weight gain and sexual maturity. The growth was slower in the presence of pesticide. In addition, carbaryl treatments showed inhibited enzyme activity in the first weeks of the vermicomposting process, slowing down organic matter biodegradation. The dynamics of the vermicomposting process can be followed by combining easily detectable parameters related to the global microbial metabolism: a traditional chemical (water‐soluble C/water‐soluble N) and biochemical (dehydrogenase activity/water‐soluble C) index, were calculated. In particular, this last seemed more useful in characterizing the vermicomposting process even a longer maturation time (10–18 wk).
Single‐Phase Microemulsification of a Complex Light‐Nonaqueous‐Phase‐Liquid: Laboratory Evaluation of Several Mixtures of Surfactant/Alcohol Solutions
Authors: Rhue R. Dean , Rao P. Suresh C. , Annable Michael D.
Published: July 2010

A recent advance in conventional pump‐and‐treat technology for aquifer remediation involves the use of surfactant‐alcohol mixtures that will form a clear, transparent, thermodynamically stable oil‐in‐water microemulsion on contact with a residual non‐aqueousphase‐liquid (NAPL). An initial screening of 86 commercial‐grade surfactants for aqueous solubility resulted in selection of 58 that were further tested in batch experiments to evaluate the capacity to solubilize a complex NAPL waste collected from a Superfund site (Operable Unit OU‐1) at Hill AFB, UT. The selected group of 58 surfactants represented six classes of anionic, nine classes of nonionic, and one class of amphoteric surfactants. Batch studies on NAPL solubilization identified a number of surfactants suitable for use in the field demonstration phase of the project; a further criterion in surfactant selection was that the flushing solution had a viscosity <2 cp. The best surfactants among this group had HLB (hydrophilic‐lipophilic balance) values between 12 and 13, and solubilized 10 to 20 g L−1 of the OU‐1 NAPL when the surfactant concentration was 3%. Column tests using NAPL‐coated glass beads showed that the more efficient surfactants could remove >90% of the NAPL after flushing with <10 pore volumes. Brij 97, an ethoxylated alcohol ether surfactant, showed a high capacity for solubilizing the OU‐1 NAPL. In a column test using contaminated Hill AFB aquifer material, flushing with a mixture of 3% Brij 97 and 2.5% n‐pentanol removed essentially all of the mass of nine target analytes in the NAPL after flushing with <10 pore volumes without mobilizing the NAPL or destabilizing aquifer colloids.
Volatile Organic Compound Losses from Sewage Sludge‐Amended Soils
Authors: Wilson S. C. , Jones K. C.
Published: July 2010

Volatile organic compounds (VOCs) applied to soil in sludge have been assumed to disappear quickly and completely. The VOC behavior in sludge‐amended soils has been studied previously only in laboratory systems where the sludged soil has been spiked with compounds of interest. Behavior in these systems may not necessarily represent compound behavior in field soils to which contaminated sludge is added. A series of laboratory microcosm experiments were designed therefore to investigate the behavior of toluene, ethyl benzene, o‐, m‐, and p‐xylene applied to soil in contaminated sludge, and factors influencing loss processes. The VOC loss from sludge‐amended soil was well described by a simple one step pseudo‐first‐order model but in certain soils was better described by a two step first‐order model. Volatilization was the predominant loss process. Rates of loss depended on sludge application rate, method of sludge application, soil properties, and on compound characteristics. Experiments indicated that spiking sludge‐amended soils gave a reasonable indication of VOC loss rates from systems amended with contaminated sludge at least over a period of 23 d. The majority of VOCs applied to soils in sludge volatilizes quickly to the atmosphere over a few to 10s of days with a small fraction lost more slowly. Potential for VOC crop uptake, livestock ingestion, and contamination of ground water (the transfer routes of most concern) is low under routine, managed applications of sewage sludge to agricultural land.
A Numerical Model to Estimate Sediment Oxygen Levels and Demand
Authors: Park Seok Soon , Jaffé Peter R.
Published: July 2010

A numerical model that simulates sediment oxygen levels and demand (SOLD) was developed and tested against field data. The model accounts for changes in sediments due to advection, diffusion, chemically and biologically mediated redox reactions, and other chemical transformations. The microbial degradation of organic matter and the interactions of the subsequent chemical constituents are described using appropriate stoichiometric relationships. Sediment oxygen demand (SOD) is computed from fluxes of oxygen and reduced compounds across the sediment‐water interface. To test the the model, simulations were compared against published data obtained from lake sediments. The model results displayed reasonable agreement with the measurements. The model was used to examine some of the major factors that affect the sediment oxygen demand. Results show that although fluxes of methane and ammonia increase with an increasing C rain rate, the oxygen flux remains almost constant for the simulations conducted. For an increase in bloturbation anti,or temperature, however, all fluxes increase significantly. The oxygen concentration at the sediment/water interface also affects the SOD significantly, especially the fraction of the total SOD that is due to the flux of oxygen into the sediments. The fraction of the SOD that is due to the oxidation of ammonia increases with increasing oxygen concentration at the sediment/water interface, while the fraction associated to the methane release and its oxidation decreases slightly because more organic C is oxidized aerobically. The contribution of reduced manganese, iron, and sulfide to the SOD are relatively low, due to their precipitation with other chemical species.
Mycobacteria in Runoff Waters from Natural and Drained Peatlands
Authors: Iivanainen Eila , Sallantaus Tapani , Katila Marja‐Leena , Martikainen Pertti J.
Published: July 2010

To assess the effect of peatland type and of forest‐drainage performed 30 yr earlier on the occurrence of mycobacteria in runoff‐waters, the counts of culturable mycobacteria were followed during a snow‐free season. Runoff‐waters were from a natural and a drained peatland and each had a different nutrient status. Samples were collected in May, June, August, and October of 1992. Mycobacteria were isolated from all waters. The highest culturable counts were detected in August (up to 7.3 × 103 CFU/L). The runoff‐waters from the two natural peatlands had similar median counts, whereas lowering of the water table by drainage slightly increased the mycobacterial counts in most cases. Changes in vegetation, such as a decrease in the coverage of Sphagnum species, or soil characteristics following drainage had little effect on the occurrence of mycobacteria in the runoff‐waters, even though Sphagnum vegetation has been regarded as important for the growth of these bacteria. The counts of mycobacteria in the runoff‐waters correlated with precipitation but not with air temperature. This indicates that the mycobacterial growth took place mainly in vegetation and soil, not in the runoff‐waters. When total runoff during May to October was taken into account, the leaching rates of mycobacteria from all catchments were about 4 to 5 × 1011 CPU km−2. Thus drainage had a negligible effect on the leaching of mycobacteria from peatlands.
Invasive Plant Species and Microbial Processes in a Tidal Freshwater Marsh
Authors: Otto Sibylle , Groffman Peter M. , Findlay Stuart E. G. , Arreola Anna E.
Published: July 2010

Vegetation has a strong influence on N retention in wetlands via direct uptake and by indirect effects on microbial N uptake and denitrificafion. Vegetation change in freshwater tidal marshes is dynamic due to both natural and anthropogenic factors and these changes may influence the water quality maintenance value (i.e., the ability to absorb exogenous N) of these marshes. We measured sediment microbial biomass and activity and plant N content and height in stands of Lythrum salicaria (L.), Phragmites australis [(Cav.) Trin. Ex Steud], and Typha angustifolia (L.) in 1995 and 1996 in Tivoli North Bay, a tidal freshwater marsh along the Hudson River in Dutchess County, New York. Lythrum and Phragmites are invasive plants that have displaced Typha in significant areas of this marsh over the past few decades. A fertilizer (two 5 g N m−2 additions of urea) response study was conducted in 1996. There were few differences in microbial biomass and activity and response to N addition between the different plants despite marked differences in plant biomass and N content and significant annual variation in several variables. Although plant change has been dramatic in this marsh, and the new plants appear to cycle N differently than the native plant, microbially‐based water quality functions may not have been affected by this change.
A Dual‐Porosity Model to Quantify Macropore Flow Effects on Nitrate Leaching
Authors: Larsson Martin H. , Jarvis Nicholas J.
Published: July 2010

The dual‐porosity model MACRO was coupled with the N turnover and leaching model SOILN to quantify macropore flow effects on nitrate (NO3) leaching from structured soils. This was done by comparing model simulations performed with and without macropore flow with measurements of tile drain flow, NO3 contents in the soil profile, NO3 concentrations in drain discharge, and N in harvested grain made in an 8‐yr field experiment on a day soil. Macropore flow had only small effects on the soil hydrology, so that the MACRO model could give good predictions of the accumulated tile drain discharge for simulations both with and without macropore flow. By taking macropore flow into account, the SOILN model could satisfactorily depict the NO3 amounts in the soil and harvested grain and the leaching pattern, while simulations without macropore flow could not match all measured components of the N mass balance. In simulations with macropore flow, 62% of the simulated NO3‐N concentrations in drain flow were within a factor of 1.5 of measured values, while simulating without macropore flow resulted in only 35% of concentrations within a factor of 1.5 of the measured values. A comparison of simulations with and without macropore flow showed that macropore flow reduced NO3‐N leaching by 28% from June 1990 to July 1995, but with large variations found between different years (from 3–45%). However, for shorter periods, macropore flow increased leaching. The results demonstrate the importance of macropore flow for NO3 transport in structured soils.
Arsenic Solubility and Attenuation in Soils of the Madison River Basin, Montana: Impacts of Long‐Term Irrigation
Authors: Jones C. A. , Inskeep W. P. , Bauder J. W. , Keith K. E.
Published: July 2010

Arsenic concentrations in 8S0 km of the Madison and Upper Missouri Rivers exceed the Montana State human health standard (0.24 µM). In addition, ground water As concentrations in the northern portion of the Lower Madison River Valley are above the federal drinking water standard (0.67 µM) and correlate with high soluble As levels in overlying soils. The objectives of this study were to determine processes affecting As solubility in soils of the Madison and Upper Missouri River Basins and assess potential impacts of long‐term irrigation with As‐rich river water on As mobility. Sixteen irrigated (>20 yr of irrigation) and nonirrigated (never irrigated) soils were sampled in four major regions adjacent to the Madison and Upper Missouri Rivers. There were no significant differences (α = 0.05) in total or soluble As levels between irrigated and nonirrigatcd soils within any of the four regions. In addition, sorption coefficients (Kd values) in six paired soils selected for additional chemical characterization were not significantly different (α = 0.05) between irrigated and nonirrigated soils. Ammonium oxalate extractable Fe and Mn concentrations were found to be positively correlated with Kd, and Olsen P concentration was found to be negatively correlated with Kd based on a multiple linear regression (r2 = 0.92). Sequential extractions performed for a subset of soils showed that labile As concentrations were similar between irrigated and nonirrigated soils. Soils that had been irrigated for >100 yr had additional As sorption capacities of at least 3 mg kg−1 in saturated column studies following 30 yr of simulated irrigation. Based on this suite of data, it was determined that irrigation history has not significantly affected As solubility or attenuation capacities in soils of the study area.
Determining Travel Time and Stream Mixing using Tracers and Empirical Equations
Authors: Verstraeten I. M. , Soenksen P. J. , Engel G. B. , Miller L. D.
Published: July 2010

Water‐supply managers need adequate warning to protect water supplies if a contaminant is spilled in an upgradient tributary. The city of Lincoln draws water from alluvium associated with the Platte River near Ashland, eastern Nebraska. Using constant‐rate injection methods and a conservative tracer, travel time and degree of mixing of contaminants in the Elkhorn and Platte Rivers were evaluated in 1995 and 1996. The results indicate that, for flows of 584 to 162 m3/s in the Platte River at Ashland with 13 to 28% of its flow contributed by the Elkhorn River, 8.2 to 13.2 h are required for the leading edge of a chemical plume to travel from the Elkhorn River at Waterloo to the Platte River at Ashland. The peak concentration of a chemical spilled as a slug in the Elkhorn River near Waterloo would pass the well field after 11.3 to 16.1 h. Existing empirical equations for calculation of travel time were shown to apply to reaches of streams studied, but underestimated the leading edge up to 14% and overestimated the plateau concentration up to 11% at Site 5. However, time of travel may be influenced by the relative contribution of a tributary. The plateau concentration of the chemical in the Platte River at Ashland was 45 to 60% of its concentration in the Elkhorn River. The degree of mixing of the tracer in the Platte River at Ashland increased from 53 to 65% as the relative contribution of the Elkhorn River increased.
Surface Water‐Ground Water Interaction: Herbicide Transport into Municipal Collector Wells
Authors: Verstraeten I. M. , Carr J. D. , Steele G. V. , Thurman E. M. , Bastian K. C. , Dormedy D. F.
Published: July 2010

During spring runoff events, herbicides in the Platte River are transported through an alluvial aquifer into collector wells located on an island in the river in 6 to 7 d. During two spring runoff events in 1995 and 1996, atrazine [2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine] concentrations in water from these wells reached approximately 7 µg/L, 70 times more than the background concentration in ground water. Concentrations of herbicides and metabolites in the collector wells generally were one‐half to one‐fifth the concentrations of herbicides in the river for atrazine, alachlor [2‐chloro‐2′‐6′‐diethyl‐N‐(methoxymethyl)‐acetanilide], alachlor ethane‐sulfonic acid (ESA) [2‐((2,6‐diethylphenyl) (methoxymethyl)amino)‐2‐oxoethane‐sulfonic acid], metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl)acetamide], cyanazine [2‐((4‐chloro‐6‐(ethylamino)‐1,3,5 triazin‐2‐yl)‐amino)‐2‐methylpropionitrile], and acetochlor [2‐chloro‐N‐(ethoxymethyl)‐N‐(2‐ethyl‐6methyl‐phenyl) acetamide], suggesting that 20 to 50% river water could be present in the water from the collector wells, assuming no degradation. The effect of the river on the quality of water from the collector wells can be reduced through selective management of horizontal laterals of the collector wells. The quality of the water from the collector wells is dependent on the (i) selection of the collector well used, (ii) number and selection of laterals used, (iii) chemical characteristics of the contaminant, and (iv) relative mixing of the Platte River and a major upstream tributary.
A Unified Sorption Variable for Environmental Applications of the Freundlich Equation
Authors: Chen Z. , Xing B. , McGill W. B.
Published: July 2010

The Freundlich equation (x/m = Kf C1/ne) has been used widely in sorption studies in chemistry and environmental research. Two problems arise in comparing sorbate‐sorbent systems if Ce ≠ 1 or if 1/n values differ. First, it is often not possible to compare Kf values from the literature if they were derived from different units of x/m and Ce. Second, the exponent 1/n, determines the interpretation of Kf. Consequently, comparing values of Kf or Koc—f is problematic. We propose a way to characterize sorption dynamics in systems that follow the Freundlich isotherm that avoids problems caused by comparing Kf values. We show that: (i) The units of Kf are: mmol1‐1/n kg−1 L1/n, or mg1‐1/n kg−1 L1/n, etc. depending on the units of x/m and Cc. Therefore, Kf parameters cannot be compared among samples whenever the 1/n parameters are different; (ii) For Kf values that are associated with different units, the units‐conversion factor for Kf is also a function of 1/n. It has the form of: A1‐1/n, where A is the units‐conversion factor if 1/n = 1; (iii) We propose a new variable, Ku, to unify the units of Kf and to conduct sensitivity analyses of Kf and 1/n. Numerically Ku is the slope, (x/m)/Ce, of the sorption isotherm at any value of Ce or x/m and has units of L kg−1.
Determination of Suspended Sediment Concentrations and Particle Size Distributions Using Pressure Measurements
Authors: Lewis Alan J. , Rasmussen Todd C.
Published: July 2010

We present an automated, in‐situ technique for measuring suspended‐sediment concentrations and particle‐size distributions. The technique uses pressure transducers to continuously monitor the fluid density, which is shown to be directly related to the mass of sediments suspended in the water column. We estimate the depth‐integrated mass of 5 g of suspended sediments with an accuracy of 3%, corresponding to a suspended sediment concentration of 542 ± 14 mg L−1. Particle‐size distributions of the sediments were estimated from the rate of change of the suspended‐sediment concentrations coupled with Stokes' Law. We evaluated the accuracy using three size classes of precision glass microspheres. Good agreement between observed and calculated fall times was only found for the smallest size fraction (106 to 150 µm). Larger particles (180 to 250 µm and 300 to 425 µm) fell slower than predicted by Stokes' Law, presumably due to the onset of turbulent flow around the particles. Also, equal masses of two different sizes of microspheres did not fall independently of each other. The larger microspheres were slowed by the presence of the smaller particles while the smaller microspheres were accelerated, presumably due to entrainment of smaller particles in the wake of the larger particles. Application to laboratory characterization of soil sedimentation processes, as well as field applications for automated suspended sediment monitoring, provides the ability for real‐time determination of depth‐integrated sediment characteristics.
Co‐Application Effects of Water Treatment Residuals and Biosolids on Two Range Grasses
Authors: Ippolito J. A. , Barbarick K. A. , Redente E. F.
Published: July 2010

Alum [Al2(SO4)314H2O] is commonly used in the municipal water treatment process to destabilize colloids for subsequent flocculation and water clarification. Water treatment residuals (WTR) can be classified as a waste material from these treatment plants. Concerns over land application of WTR are due to its postulated reduction of plant available P and potential plant Al toxicity with increasing WTR rates. Co‐application of WTR with biosolids may benefit municipalities with biosolids inherently high in P concentrations and in terms of a cost savings by landfill avoidance. In a greenhouse study, we investigated the efficacy of co‐application of WTR and biosolids to the native shortgrass prairie species blue grama (Bouteloua gracilis H.B.K. Lag) and western wheatgrass [Pascopyrum smithii (Rydb.) A. Love]. Our objectives were to quantify co‐application effects on plant P and Al concentrations and uptake, biomass production, and WTR P adsorbing capacity. With blue grama, we observed a positive linear relationship between increasing WTR rate and yield and a negative linear relationship with increasing WTR rate and shoot P and Al concentration (P < 0.10). With western wheatgrass, increasing WTR rate produced a negative quadratic effect on shoot Al concentration (P < 0.10). Some investigators have observed P deficiency symptoms associated with WTR application; however, we did not. Our adsorption study indicated that co‐mixing of the City of Fort Collins, CO, WTR and biosolids at ratios of 8:1 will adsorb all soluble biosolids P. Beyond this ratio the WTR could adsorb all biosolids available P and possibly some soil‐borne P.
Chelate‐Assisted Phytoextraction of Lead from Contaminated Soils
Authors: Cooper E. M. , Sims J. T. , Cunningham S. D. , Huang J. W. , Berti W. R.
Published: July 2010

Phytoextraction, a remediation strategy for lead (Pb)‐contaminated soils that removes soil Pb through plant uptake and harvest, may be enhanced by use of synthetic chelates. We evaluated Pb desorption from four contaminated soils (total Pb 1278‐14 349 mg kg −1) by seven chelates (CDTA, DTPA, EDDHA, EGTA, HEDTA, HEIDA, and NTA) at three rates (0.2, 2.0, and 20 mmol chelate kg soil−1) . The three most effective chelates (CDTA, DTPA, and HEDTA) were used in greenhouse studies with an uncontaminated soil and a Pb‐contaminated soil (total Pb = 3212 mg kg−1) to determine the effect of chelate type and rate on growth, Pb uptake, and plant elemental composition. Lead desorption varied with chelate and soil and increased with chelate rate, averaging 948 mg Pb kg−1 at the 20 mmol kg−1 rate vs. 28 mg Pb kg−1 by the control. The general ranking of chelate effectiveness, based on total Pb desorbed, was HEDTA > CDTA > DTPA > EGTA > HEIDA > EDDHA ~ NTA. Plant uptake of Pb from the contaminated soil was enhanced by CDTA, DTPA, and HEDTA, but with even the most effective treatment (corn, high CDTA rate), the amount of Pb extracted by plants was rather low (0.4 kg Pb ha−1). Lead extractable by the Toxicity Characteristic Leaching Procedure) (TCLP) was increased from 9 L−1 in the control to from 47 to 174 mg L−1 in soils treated with 20 mmol kg−1 CDTA or DTPA and chelates generally caused a shift in Pb from resistant to more soluble chemical fractions.
Heavy Metal Leaching from Mine Tailings as Affected by Plants
Authors: Zhu D. , Schwab A. P. , Banks M. K.
Published: July 2010

A column experiment was conducted to determine the impact of soil cover and plants on heavy metal leaching from mine tailings and heavy metal contaminated soil. Columns made of PVC were constructed with 30 cm subsoil covered by 30 cm of mine tailings followed by 0, 30, or 60 cm of clean topsoil. Two grasses, tall fescue (Festuca arundinacea Schreb.) and big bluestem (Andropogon gerardii), were grown in the columns. The columns were leached at a slow rate for 1 yr with a 0.001 M CaCl2 solution under unsaturated conditions. The presence of both tall fescue and big bluestem increased Zn and Cd concentrations in the leachate. Lead concentrations in leachates were not affected by the presence of plants. Although plants generally reduced the total amount of water leached, total mass of Zn and Cd leached generally was not impacted by plants. Total mass of Pb leached was positively correlated (r = 0.9) with total leachate collected from each column. Covering the mine tailings with 60 cm of topsoil (with or without vegetation) increased the mass of Zn and Cd leached relative to no topsoil. When the subsoil was absent, Zn and Cd leaching increased by as much as 20‐fold, verifying the ability of soil to act as a sink for metals. Mine tailing remediation by establishing vegetation can reduce Pb movement but may enhance short‐term Cd and Zn leaching. However, the changes were relatively small and do not outweigh the benefits of using vegetation in mine tailings reclamation.
Phosphate Leaching Responses from Unperturbed, Anaerobic, or Cattle Manured Mesotrophic Sandy Loam Soils
Authors: Magid Jakob , Jensen Marina Bergen , Mueller Torsten , Hansen Hans Christian Bruun
Published: July 2010

Control of P from sewage outlets has not led to expected improvement of Danish freshwater quality, calling the diffuse P losses especially from drained agricultural land into question. We studied some mechanisms for P loss from the fertilized topsoil from selected catchments that have been monitored for P losses: (i) losses due to desorption of P from A horizons enriched throughout the last decades by fertilization, (ii) losses of P associated with temporarily reducing conditions imposed on A horizons, and (iii) losses associated with application of fresh cattle manure to the soil surface or by mixing into the soil matrix. The effluent concentrations of P from 15 intact topsoil samples were 10 to 40 times lower than what could be expected from batch studies, presumably due to nonhomogeneous flow conditions. Addition of solid cattle feces by incorporation or directly on the surface had markedly differing effects on P leaching. While incorporation did result in a 10‐ to 20‐fold increase in effluent P concentration, surface application resulted in a further 10‐ to 20‐fold higher effluent concentration of molybdate‐reactive P. These results indicate that while desorption from the soil matrix is likely to be much less than expected from batch chemical considerations, special attention should be given to drained pastures, where the important P source may not be the soil matrix per se, but fecal remnants on the surface, that may be transported directly to the drains through macropores. Furthermore, reductive dissolution of Fe associated P may be of some importance.
The Pre‐Sidedress Soil Nitrate Test and Nitrate Leaching from Corn
Authors: Guillard Karl , Morris Thomas F. , Kopp Kelly L.
Published: July 2010

The pre‐sidedress soil nitrate test (PSNT) is recommended in many states as a best management practice (BMP) for corn (Zea mays L.). A 2‐yr study was conducted in Connecticut on a Woodbridge fine sandy loam soil (coarse loamy, mixed, mesic Aquic Dystrochrept) to determine NO3‐N concentrations and losses in soil water from corn managed with three different N fertilization regimes: (i) PRE, 196 kg N ha−1 applied preplant; (ii) PSNT‐1, 90 kg N ha−1 applied at preplant and any remaining N needs estimated by the PSNT (0 kg ha−1 in 1995 and 45 kg ha−1 in 1996); and (iii) PSNT‐2, no preplant N and all N needs estimated by the PSNT (34 kg ha−1 in 1995 and 123 kg ha−1 in 1996). Percolate was collected with zero‐tension pan lysimeters. Flow‐weighted NO3‐N concentrations from the PRE treatment were 22.3 mg L−1 in 1995 and 17.4 mg L−1 in 1996; the PSNT treatments were <8.0 mg L−1. Losses of NO3‐N as a percent of N applied in 1995 were 20%, 10%, and 12% for PRE, PSNT‐1, and PSNT‐2, respectively, and 31%, 21%, and 21%, respectively, in 1996. Greatest leaching losses occurred after corn harvest. Corn yields were not significantly (P > 0.05) different among N treatments. These findings suggest that a well calibrated soil N test can reduce excess fertilization and the potential for NO3 contamination of ground water.
Phosphorus Sorption in Manured Atlantic Coastal Plain Soils under Flooded and Drained Conditions
Authors: Vadas P. A. , Sims J. Thomas
Published: July 2010

Artificially drained, agricultural soils that are high in P and have seasonally fluctuating water tables may be significant nonpoint sources of P to Delaware's Inland Bays. Topsoil, unamended and amended with 4 g kg−1 poultry litter (PL), and subsoil horizons from two soil series in the Inland Bays watershed were flooded for 28 d and drained for 14 d at 25°C. Soil pH and redox potential (Eh) were measured (mV) and P sorption isotherms were constructed for each horizon under oxidized, flooded, and drained conditions. For each isotherm, P sorption maxima (bmax), P sorbed at a solution P concentration of 1.0 mg L−1 (b1.0), and the equilibrium P concentration at zero sorption (EPC0) were calculated. Flooding decreased Eh and increased pH, and draining returned Eh and pH to near initial values. Flooding and draining decreased bmax in all horizons. The b1.0 values were always significantly less than bmax values; however, flooding and draining had inconsistent effects on b1.0 values. Flooding increased EPC0 in the unamended Pocomoke A horizon, but decreased EPC0 in the same PL‐amended horizon. Draining reduced EPC0 values in both Pocomoke A horizons. Flooding and draining had little effect on EPC0 in other horizons. Our data suggest that land application of PL and fluctuating water tables may increase the potential for P loss from soils through both a decrease in soil P sorption capacity and an increase in solution P concentrations in topsoils.
Agrichemicals in Ground Water of the Midwestern USA: Relations to Soil Characteristics
Authors: Burkart Michael R. , Kolpin Dana W. , Jaquis Robert J. , Cole Kevin J.
Published: July 2010

A comprehensive set of soil characteristics were examined to determine the effect of soil on the transport of agrichemicals to ground water. This paper examines the relation of local soil characteristics to concentrations and occurrence of nitrate, atrazine (2‐chloro‐4 ethylamino‐6‐isopropylamino‐s‐trazine), and atrazine residue [atrazine + deethylatrazine (2‐amino‐4‐chloro‐6‐isopropylamino‐s‐triazine) + deisopropylatrazine (2‐amino‐4‐chloro‐6‐ethylamino‐s‐triazine)] from 99 wells completed in unconsolidated aquifers across the midwestern USA. The occurrence and concentrations of nitrate and atrazine in ground water were directly related to soil characteristics that determine the rate of water movement. The substantial differences in the relations found among soil characteristics and nitrate and atrazine in ground water suggest that different processes affect the transformation, adsorption, and transport of these contaminants. A multivariate analysis determined that the soil characteristics examined explained the amount of variability in concentrations for nitrate (19.0%), atrazine (33.4%), and atrazine residue (28.6%). These results document that, although soils do affect the transport of agrichemicals to ground water, other factors such as hydrology, land use, and climate must also be considered to understand the occurrence of agrichemicals in ground water.
Giardia Cyst and Cryptosporidium Oocyst Survival in Water, Soil, and Cattle Feces
Authors: Olson Merle E. , Goh Jeanette , Phillips Michael , Guselle Nicole , McAllister Tim A.
Published: July 2010

Giardiasis and cryptosporidiosis are gastrointestinal diseases caused by protozoan parasites that may infect domestic animals, wildlife and human beings. The ability of cysts and oocysts of these parasites to persist in the environment was determined because agricultural fecal waste has the potential to contaminate municipal water supplies. The degradation rate and viability of Giardia cysts and Cryptosporidium oocysts in water, cattle (Bos taurus) feces, and soil was evaluated at temperatures of −4, 4, and 25°C for up to 12 wk. Cysts and oocysts were enumerated after staining samples with a specific fluorescent monoclonal antibody and the viability was determined using propidium iodide dye exclusion and mouse infectivity assays. Giardia cysts were noninfective in water, feces, and soil following 1 wk of freezing to −4°C and within 2 wk at 25°C. At 4°C Giardia cysts were infective for 11 wk in water, 7 wk in soil, and 1 wk in cattle feces. Cryptosporidium oocysts were more environmentally resistant. At −4 and 4°C, the oocysts could survive in water and soil for >12 wk but degradation was accelerated at 25°C. Cryptosporidium oocysts also were degraded more rapidly in feces and in soil containing natural microorganisms. Contaminated cattle feces should be distributed on fields during warmer weather and after 12 wk of storage to reduce potential waterborne transmission following heavy runoffs.
Practical and Innovative Measures for the Control of Agricultural Phosphorus Losses to Water: An Overview
Authors: Sharpley Andrew , Foy Bob , Withers Paul
Published: July 2010

Inputs of P are essential for profitable crop and livestock production. However, its export in watershed runoff can accelerate the eutrophication of receiving fresh waters. The specialization of crop and livestock farming has created regional imbalances in P inputs in feed and fertilizer and output in farm produce. In many areas, soil P exceeds crop needs and has enriched surface runoff with P. This paper provides a brief overview of P management strategies to maintain agricultural production and protect water quality that were discussed at the conference, “Practical and Innovative Measures for the Control of Agricultural Phosphorus Losses to Water,” sponsored by the Organization for Economic Cooperation and Development and held in Antrim, Northern Ireland, June 1998. The purpose of the conference was to assess current strategies for reducing the loads and concentrations of P from agricultural land to surface waters. Topics discussed at the interdisciplinary conference and reviewed here included sustainable P management in productive agriculture; assessing land application of P; evaluating and modeling P transport and transformations in soil, runoff, streams, and lakes; and implementation of integrated best management practices (BMPs). From these discussions, measures to control agricultural P transfer from soil to water may be brought about by optimizing fertilizer P use‐efficiency, refining animal feed rations, using feed additives to increase P absorption by the animal, moving manure from surplus to deficit areas, and targeting conservation practices, such as reduced tillage, buffer strips, and cover crops, to critical areas of P export from a watershed.
Terminology for Phosphorus Transfer
Authors: Haygarth P. M. , Sharpley A. N.
Published: July 2010

The transfer of P from agricultural land to water attracts scientists of varied expertise. The multidisciplinary nature of factors controlling P transfer has lead to confusions in communication because of inappropriate or ambiguous use of terminology. Therefore, we have attempted to classify terminology for P transfer into: (i) processes (or modes) (e.g., erosion, leaching, incidental) (ii) pathways (e.g., overland flow, subsurface flow, drainage flow), and (iii) form terms (e.g., those that can be described in soil or water samples). A method of classifying pathways by scale, plane, and time is suggested and a particular caution is noted for leaching, which is a process, not a pathway, and runoff (a vaguely defined pathway). Current terminology for forms in water is confusing because terms such as soluble, dissolved, particulate, inorganic, and organic can be technically incorrect if used inappropriately when describing P forms involving membrane filtration and Murphy‐Riley Mo‐blue chemistry. We suggest an improved method for describing the forms of P in waters, which is operationally defined and states the analytical method and size of filter used.
Nutrient Management Planning: Justification, Theory, Practice
Authors: Beegle D. B. , Carton O. T. , Bailey J. S.
Published: July 2010

Traditionally, nutrient management has been concerned with optimizing the economic return from nutrients used for crop production. Today, the agronomic and economic requirements of nutrient management remain central, but in addition, the process must consider the potential impact of these nutrients on environmental quality. The nutrient‐management process is critical for maximizing the economic benefit from nutrients while minimizing the environmental impact. This process includes assessment, analysis, decision making, evaluation and refinement. A tactical nutrient‐management plan developed from this process must be based on a firm set of strategic objectives agreed upon by the farmers and society. The nutrient‐management process must also be practical to implement, if the performance goals are to be met. While nutrient‐management plans have resulted in benefits to farmers and society, implementation has not been as great as desired. Several factors have been identified as key to the successful implementation of nutrient‐management planning: the full participation of a broad range of stakeholders, the use of established infrastructure, targeted nutrient‐management planning efforts, voluntary vs. mandatory programs, and the economics of nutrient management. Experiences in Pennsylvania, the Republic of Ireland, and Northern Ireland illustrate aspects of the implementation of the nutrient management process.
Potential for Preferential Pathways of Phosphorus Transport
Authors: Simard R. R. , Beauchemin S. , Haygarth P. M.
Published: July 2010

This paper briefly reviews the existing literature and uses evidence from three studies to demonstrate the occurrence of preferential pathways of P transport through soil. Studies conducted in the St. Lawrence lowlands, Canada, indicated that particulate P (PP‐i.e., >0.45 µm) the main fraction of total P (TP) in tile‐drainage water generated by storm events after periods of low rainfall. In the remainder of the year, the concentration of TP and P forms were related to soil texture, primary tillage intensity and frequency, and showed wide seasonal variations. For a study conducted in the UK under grassland, higher TP concentrations were found in near‐surface runoff (0–30 cm) compared with concentrations measured in drainflow. Water passing through the artificial drainage system had a higher proportion of PP (43%) than water passing close to (<30 cm) or over the soil surface (31%). Installation of tile drainage in a poorly draining soil reduces P transfer by improving the infiltration capacity, thereby reducing overland flow volume and allowing P to be retained/sorbed by the soil matrix. Because of the absence of tillage, permanent grasslands accumulate P near the surface. We hypothesize that, if the soil P store is coincident with preferential flow pathways (either artificial mole drainage channels or natural macropores), permanent grassland will be vulnerable to transfer large amounts of P through subsurface pathways. Phosphorus transfer through preferential flow pathways may be particularly important after storm events that rapidly follow periods of drought and/or surface P inputs as inorganic fertilizer or manure.