bluuebunny/crossref_metadata_2025 huggingface dataset:
Water‐Soluble and Solid‐State Speciation of Phosphorus in Stabilized Sewage Sludge
Authors: Huang Xiao‐Lan , Shenker Moshe
Published: June 2010

Three chemicals, ferrous sulfate (Fe‐sul), calcium oxide (CaO), and aluminum sulfate (alum), were used to stabilize phosphorus (P) in fresh, anaerobically digested sewage sludge (FSS). The chemically stabilized sludge materials and biosolids compost (BSC) were compared with the FSS with respect to water‐soluble phosphorus (WSP) content in its inorganic (WSPi) and organic (WSPo) forms as well as water‐soluble organic carbon (DOC). Solid‐state P speciation was further probed by X‐ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy‐dispersive X‐ray elemental spectrometry (EDXS). Water‐soluble P was effectively controlled by a wide range of Fe‐sul or CaO additions to the sludge (Ca to P ratio = 3.47–17.72, Fe to P ratio = 1.01–16.53), but by only a narrow range (Al to P ratio = 1.04–2.87) of alum addition. The WSP content in the BSC was also depressed, but to a lesser extent. The pH in the treated sludge ranged from 3.0 to 12.5 and served as a key factor to control P chemistry. No correlation was observed between DOC and WSPo No crystallized Ca‐P minerals were detected in the CaO‐stabilized sludge, but brushite crystallization seemed to be obtained by low addition of Fe‐sul and alum. Variscite and strengite crystallization was obtained following high addition of Fe‐sul or alum, as detected by XRD and SEM–EDXS. Adsorption of P by newly formed Fe‐hydroxide seems to play an important role in the Fe‐sul‐stabilized sludge. We concluded that administration of the tested chemicals at the proper rate can effectively reduce the hazard of P release and leaching from sludge.
Fecal Contamination of Pastoral Wetlands
Authors: Collins Robert
Published: June 2010

Near‐channel hill‐country wetlands draining steep pastoral land in New Zealand exhibit high levels of fecal contamination at a range of flows. This contamination is attributed to both the transport of bacteria into a wetland from the surrounding catchment and the direct excretion of fecal material onto wetlands by grazing cattle. E. coli concentrations observed at low to moderate flow at 20 sites varied between 0.5 × 101 and 2 × 104 most probable number (MPN) 100 mL−1 High flow concentrations measured at two wetlands ranged up to 6 × 106 MPN 100 mL−1 and yielded storm period bacterial loads of between 1 × 106 and 3 × 1010 MPN per event. Given the disproportionately large fraction of surface and subsurface flow from the catchment that passes through the wetlands, these yields represent a large proportion of the total loss of bacteria from steep grazed hillsides, across a range of storm events. Cattle are attracted to the smaller, shallower wetlands for grazing in both summer and winter. Excluding stock from shallow wetlands may therefore yield improvements in bacterial water quality, although accurately quantifying this improvement is difficult without long‐term studies. Cattle are not attracted to larger, deeper wetlands, presumably for fear of entrapment, and fencing them is unlikely to realize significant improvements in bacterial water quality. A statistical model incorporating solar radiation and flow explains 87% of the variance in E. coli concentrations across five monitored rainfall events. A positive correlation was found between solar radiation and E. coli concentration. The study was conducted in winter when clear, sunny days are relatively cold. Solar radiation on these days appears to be too weak to promote die‐off but the colder temperatures aid survival.
Phosphorus Runoff from Agricultural Land and Direct Fertilizer Effects: A Review
Authors: Hart Murray R. , Quin Bert F. , Nguyen M. Long
Published: June 2010

Phosphorus (P) is one of the most important mineral nutrients in agricultural systems, and along with nitrogen (N), is generally the most limiting nutrient for plant production. Farming systems have intensified greatly over time, and in recent years it has become apparent that the concomitant increase in losses of N and P from agricultural land is having a serious detrimental effect on water quality and the environment. The last two decades have seen a marked increase in research into the issues surrounding diffuse losses of P to surface and ground water. This paper reviews this research, examining the issue of P forms in runoff, and highlighting the exceptions to some generally held assumptions about land use and P transport. In particular the review focuses on P losses associated with recent P fertilizer application, as opposed to organic manures, both on the amounts and the forms of P in runoff water. The effects of the physicochemical characteristics of different forms of P fertilizer are explored, particularly in relation to water solubility. Various means of mitigating the risk of loss of P are discussed. It is argued that the influence of recent fertilizer applications is an under‐researched area, yet may offer the most readily applicable opportunity to mitigate P losses by land users. This review highlights and discusses some options that have recently become available that may make a significant contribution to the task of sustainable management of nutrient losses from agriculture.
Septic Systems as Potential Pollution Sources in the Cannonsville Reservoir Watershed, New York
Authors: Day Laurence
Published: June 2010

On‐site septic systems require appropriate soil characteristics to provide effective wastewater treatment. The objective of this study was to evaluate siting practices and treatment efficacy of on‐site septic systems within the Cannonsville Reservoir watershed (115900 ha) in the state of New York. Using digital soil survey data, a database of on‐site conditions was developed from more than 1100 existing septic system siting records. Soil map units were grouped into four classes based on their suitability to meet common septic system design criteria. A geographic information system was found to be a useful tool for assessment and visual display of septic system and landscape information. Geographic information system analysis indicated that while 80% of soils in the watershed were found to have characteristics that interfere with septic system function, 69% of septic systems installed were of designs suited for soils with no or few restrictive parameters. Since the designs of many septic systems have relied heavily on horizontal distance to streams (mean = 130 m) to provide adequate treatment, potential failures would lead to discharge of compounds of environmental concern, such as phosphorus, with public health implications. The results imply that many septic systems functioning in the watershed are in need of design improvements.
Effect of Surfactants on Solubilization and Degradation of Phenanthrene under Thermophilic Conditions
Authors: Wong Jonathan W. C. , Fang Min , Zhao Zhenyong , Xing Baoshan
Published: June 2010

The bioavailability and biodegradation of polycyclic aromatic hydrocarbons (PAHs) can be increased through the addition of surfactants. Previous studies of this nature have been conducted under mesophilic conditions. Hence, the aim of the present study was to investigate the effects of synthetic surfactants and biosurfactants on solubilization and degradation of phenanthrene (PHE) in a series of batch solution experiments under thermophilic conditions. Tween 80, Triton X‐100, and biosurfactants produced from Pseudomonas aeruginosa strain P‐CG3 (P‐CG3) and Pseudomonas aeruginosa ATCC 9027 (P. 9027) were used in this study. Surfactants effectively enhanced the solubility of PHE at 50°C and the biosurfactant from P‐CG3 was most effective with a 28‐fold increase in apparent solubility of PHE at a concentration of 10 × critical micelle concentration (CMC) compared with the controls. However, addition of synthetic surfactants or biosurfactants inhibited the biodegradation of PHE in mineral salts medium by an isolate Bacillus sp. B‐UM. Degradation of PHE diminished with increasing surfactant concentrations, and PHE degradation was completely inhibited for all the surfactants tested when the concentrations were greater than their respective CMC. The growth test suggested that Tween 80 and biosurfactants were degradable, but preferential utilization of these surfactants as substrates was not the mechanism for explaining the inhibition of PHE biodegradation. Because of the hydrophobic property of B‐UM, degradation inhibition of PHE by surfactants was probably due to the reduction of direct contact between bacterial cells and PHE.
Variation in Root Density along Stream Banks
Authors: Wynn Theresa M. , Mostaghimi Saied , Burger James A. , Harpold Adrian A. , Henderson Marc B. , Henry Leigh‐Anne
Published: June 2010

While it is recognized that vegetation plays a significant role in stream bank stabilization, the effects are not fully quantified. The study goal was to determine the type and density of vegetation that provides the greatest protection against stream bank erosion by determining the density of roots in stream banks. To quantify the density of roots along alluvial stream banks, 25 field sites in the Appalachian Mountains were sampled. The riparian buffers varied from short turfgrass to mature riparian forests, representing a range of vegetation types. Root length density (RLD) with depth and aboveground vegetation density were measured. The sites were divided into forested and herbaceous groups and differences in root density were evaluated. At the herbaceous sites, very fine roots (diameter < 0.5 mm) were most common and more than 75% of all roots were concentrated in the upper 30 cm of the stream bank. Under forested vegetation, fine roots (0.5 mm < diameter < 2.0 mm) were more common throughout the bank profile, with 55% of all roots in the top 30 cm. In the top 30 cm of the bank, herbaceous sites had significantly greater overall RLD than forested sites (α = 0.01). While there were no significant differences in total RLD below 30 cm, forested sites had significantly greater concentrations of fine roots, as compared with herbaceous sites (α = 0.01). As research has shown that erosion resistance has a direct relationship with fine root density, forested vegetation may provide better protection against stream bank erosion.
The Reduction of Internal Phosphorus Loading Using Alum in Spring Lake, Michigan
Authors: Steinman Alan , Rediske Rick , Reddy K. Ramesh
Published: June 2010

The release of P from lake sediments, which occurs as a part of internal loading, may contribute a significant portion of the total P load to a lake. Phosphorus release rates from sediments in Spring Lake, Michigan, and the degree to which alum reduces P release from these sediments, were investigated during the summer of 2003. Triplicate sediment cores were sampled from four sites in the lake, and exposed to one of four treatments in the laboratory: (i) aerobic water column/alum, (ii) aerobic water column/no alum, (iii) anaerobic water column/alum, or (iv) anaerobic water column/no alum. Total P (TP) release rates were virtually undetectable in the alum treatments (both aerobic and anaerobic). Low, but detectable, release rates were measured in the aerobic/no alum treatment. The highest release rates were measured in the anaerobic/no alum treatments, and ranged from 1.6 to 29.5 mg P m−2 d−1 depending on how the calculations were derived. These fluxes translated to mean internal loads that ranged between 2.7 (low range) and 6.4 (high range) Mg yr−1 when extrapolated to a whole‐lake basis. Internal P loads accounted for between 55 and 65% of the total P load to Spring Lake. Although alum is a potentially effective means of reducing the sediment source of P, there is considerable uncertainty in how long an alum treatment would remain effective in this system given the current rates of external loading and the lack of information on wind‐wave action and bioturbation in Spring Lake.
Temporal Changes in Soil Partitioning and Bioaccessibility of Arsenic, Chromium, and Lead
Authors: Fendorf Scott , La Force Matthew J. , Li Guangchao
Published: June 2010

The hazard imposed by trace element contaminants within soils is dependent on their ability to migrate into water systems and their availability for biological uptake. The degree to which a contaminant may dissociate from soil solids and become available to a target organism (i.e., bioaccessibility) is therefore a determining risk factor. We used a physiologically based extraction test (PBET) to estimate the bioaccessible fraction of arsenic‐, chromium‐, and lead‐amended soil. We investigated soils from the A and B horizons of the Melton Valley series, obtained from Oak Ridge National Laboratory site, to address temporal changes in bioaccessibility. Additionally, common extractions that seek to define reactive pools of metals were employed and their correlation to PBET levels evaluated. With the exception of Pb amended to the A horizon, all other treatments exhibited an exponential decrease in bioaccessibility with incubation time. The bioaccessible fraction was less than 0.2 mg kg−1 within 30 d of incubation for As and Cr in the A horizon and for As and Pb within the B horizon; Cr in the B horizon declined to nearly 0.3 mg kg−1 within 100 d of aging. The exchangeable fraction declined with incubation period and, with the exception of Pb, was highly correlated with the decline in bioaccessibility. Our results demonstrate limited bioaccessibility in all but one case and the need to address both short‐term temporal changes and, most importantly, the soil physiochemical properties. They further reveal the importance of incubation time on the reactivity of such trace elements.
Effect of the Prestige Oil Spill on Salt Marsh Soils on the Coast of Galicia (Northwestern Spain)
Authors: Andrade M. L. , Covelo E. F. , Vega F. A. , Marcet P.
Published: June 2010

At four estuarine sites on the coast of Galicia (northwestern Spain), all of which were affected by the Prestige oil spill, soil samples were taken from polluted and unpolluted areas and their petroleum hydrocarbon contents, heavy metal contents, and other chemical and physical characteristics were measured. Oil pollution altered both chemical and physical soil properties, aggregating soil particles in plaques, lowering porosity, and increasing resistance to penetration and hydrophobicity. The chromium, nickel, copper, iron, lead, and vanadium contents of polluted soils were between 2 and 2500 times higher than those of their unpolluted counterparts and the background concentrations in Galician coastal sediments. In the cases of Cr, Cu, Ni, Pb, and V, their origin in the polluting oil was corroborated by the high correlation (r ≥ 0.74) between the concentrations of these metals and the total petroleum hydrocarbon (TPH) content of the polluted soils. Soil redox potentials ranged from −19 to −114 mV in polluted soils and 112 to 164 mV in unpolluted soils, and were negatively correlated with TPH content (p < 0.01). The low values in the polluted soils explain why the soluble fractions of their total heavy metal contents were very small (generally less than 3%, and in many cases undetectable).
Distribution and Leaching of Methyl Iodide in Soil following Emulated Shank and Drip Application
Authors: Guo Mingxin , Zheng Wei , Papiernik Sharon K. , Yates Scott R.
Published: June 2010

Methyl iodide (MeI) is a promising alternative to methyl bromide in soil fumigation. The pest‐control efficacy and ground water contamination risks of MeI as a fumigant are highly related to its gas‐phase distribution and leaching after soil application. In this study, the distribution and leaching of MeI in soil following shank injection and subsurface drip application were investigated. Methyl iodide (200 kg ha−1) was directly injected or drip‐applied at a 20‐cm depth into Arlington sandy loam (coarse‐loamy, mixed, thermic Haplic Durixeralfs) columns (12‐cm i.d., 70‐cm height) tarped with virtually impermeable film. Concentration profiles of MeI in the soil air were monitored for 7 d. Methyl iodide diffused rapidly after soil application, and reached a 70‐cm depth within 2 h. Relative to shank injection, drip application inhibited diffusion, resulting in significantly lower concentration profiles in the soil air. Seven days after MeI application, fumigated soil was uncapped, aerated for 7 d, and leached with water. Leaching of MeI was significant from the soil columns under both application methods, with concentrations of >10 μg L−1 in the early leachate. The leaching was greater following shank injection than drip application, with an overall potential of 33 g ha−1 for shank injection and 19 g ha−1 for drip application. Persistent residues of MeI remaining in soils after leaching were 50 to 240 ng kg−1, and the contents were slightly higher following shank injection than drip application. The results suggest that fumigation with MeI may pose a risk of ground water contamination in vulnerable areas.
Remediating RDX‐Contaminated Ground Water with Permanganate
Authors: Adam M. L. , Comfort S. D. , Morley M. C. , Snow D. D.
Published: June 2010

Ground water beneath the U.S. Department of Energy Pantex Plant is contaminated with the high explosive RDX (hexahydro‐1,3,5‐trinitro‐1,3,5 triazine). The USDOE Innovative Treatment and Remediation Demonstration (ITRD) program identified in situ oxidation by permanganate as a technology fit for further investigation. We evaluated the efficacy of KMnO4 to transform and mineralize RDX by determining degradation kinetics and carbon mass balances using 14C‐RDX. Aqueous RDX solutions (2–5 mg L−1) and RDX‐contaminated slurries (50% solids, w/v) were treated with KMnO4 at 1000, 2000, 4000, and 20000 mg L−1 Treating an aqueous RDX solution of 2.8 mg L−1 with 20000 mg KMnO4 L−1 decreased RDX to 0.1 mg L−1 within 11 d while cumulative mineralization proceeded for 14 d until 87% of the labeled carbon was trapped as 14CO2 Similar cumulative mineralization was obtained when Pantex aquifer material was included in the solution matrix. Other experiments using 4000 mg KMnO4 L−1 showed that initial RDX concentrations (1.3–10.4 mg L−1) or initial pH (4–11) had little effect on reaction rates. Attempts to identify RDX degradates and reaction products showed that N2O was a product of permanganate oxidation and constituted 20 to 30% of the N balance. Time‐course measurements of a 14C‐RDX solution treated with KMnO4 revealed few 14C‐labeled degradates but through liquid chromatography–mass spectrometry (LC–MS) analysis, we present evidence that 4‐nitro‐2,4‐diaza‐butanol is formed. Aquifer microcosm studies confirmed that the transformation products not mineralized by KMnO4 were much more biodegradable than parent RDX. These results indicate permanganate can effectively transform and mineralize RDX in the presence of aquifer material and support its use as an in situ chemical oxidation treatment for the Pantex perched aquifer.
Rainfall Timing and Poultry Litter Application Rate Effects on Phosphorus Loss in Surface Runoff
Authors: Schroeder P. D. , Radcliffe D. E. , Cabrera M. L.
Published: June 2010

Phosphorus (P) in runoff from pastures amended with poultry litter may be a significant contributor to eutrophication of lakes and streams in Georgia and other areas in the southeastern United States. The objectives of this research were to determine the effects of litter application rate and initial runoff timing on the long‐term loss of P in runoff from surface‐applied poultry litter and to develop equations that predict P loss in runoff under these conditions. Litter application rates of 2, 7, and 13 Mg ha−1, and three rainfall scenarios applied to 1‐ × 2‐m plots in a 3 × 3 randomized complete block design with three replications. The rainfall scenarios included (i) sufficient rainfall to produce runoff immediately after litter application; (ii) no rainfall for 30 d after litter application; and (iii) small rainfall events every 7 d (5 min at 75 mm h−1) for 30 d. Phosphorus loss was greatest from the high litter rate and immediate runoff treatments. Nonlinear regression equations based on the small plot study produced fairly accurate (r2 = 0.52–0.62) prediction of P concentrations in runoff water from larger (0.75 ha) fields over a 2‐yr period. Predicted P concentrations were closest to observed values for events that occurred shortly after litter application, and the relative error in predictions increased with time after litter application. In addition, previously developed equations relating soil test P levels to runoff P concentrations were ineffective in the presence of surface‐applied litter.
Pig Slurry Application and Irrigation Effects on Nitrate Leaching in Mediterranean Soil Lysimeters
Authors: Daudén A. , Quílez D. , Vera M. V.
Published: June 2010

Land application of animal manures, such as pig slurry (PS), is a common practice in intensive‐farming agriculture. However, this practice has a pitfall consisting of the loss of nutrients, in particular nitrate, toward water courses. The objective of this study was to evaluate nitrate leaching for three application rates of pig slurry (50, 100, and 200 Mg ha−1) and a control treatment of mineral fertilizer (275 kg N ha−1) applied to corn grown in 10 drainage lysimeters. The effects of two irrigation regimes (low vs. high irrigation efficiency) were also analyzed. In the first two irrigation events, drainage NO3–N concentrations as high as 145 and 69 mg L−1 were measured in the high and moderate PS rate treatments, respectively, in the low irrigation efficiency treatments. This indicates the fast transformation of the PS ammonium into nitrate and the subsequent leaching of the transformed nitrate. Drainage NO3–N concentration and load increased linearly by 0.69 mg NO3–N L−1 and 4.6 kg NO3–N ha−1, respectively, for each 10 kg N ha−1 applied over the minimum of 275 kg N ha−1 An increase in irrigation efficiency did not induce a significant increase of leachate concentration and the amount of nitrate leached decreased about 65%. Application of low PS doses before sowing complemented with sidedressing N application and a good irrigation management are the key factors to reduce nitrate contamination of water courses.
Phosphorus Dynamics in Soils Receiving Chemically Treated Dairy Manure
Authors: Kalbasi M. , Karthikeyan K. G.
Published: June 2010

Chemical treatment of animal manure with Al, Fe, and Ca salts appears capable of concentrating P in a smaller volume, thereby providing increased manure management options. However, little information is available on the fate of nutrients in soils receiving chemically treated manure. An incubation study (1 d to 2 yr) was conducted with three soils (Soils I, II, and III with 12, 66, and 94 mg kg−1 Bray‐1 P, respectively) and four manure treatments (one untreated and three chemical including Al‐, Fe‐, and Ca‐treated) at two rates (12.5 and 25 mg P kg−1), and a control (no manure). Subsamples were analyzed for Bray‐1 P and water‐extractable phosphorus (WEP) after eight incubation time periods. Phosphorus distribution among different fractions (soluble and loosely bound; Al‐, Fe‐, and Ca‐bound; organic P; and residual) was also determined after 1 d and 1 yr. Water‐extractable P increased when soils received untreated or Ca‐treated manure in proportion to P application rate. Water‐extractable P, however, decreased (compared with control) for Soils II and III or slightly increased for Soil I with addition of Al‐ or Fe‐treated manure. Water‐extractable P decreased sharply between 1 d and 1 to 2 wk and then remained relatively constant or increased slightly up to 2 yr depending on treatment and soil type. Bray‐1 P increased for all treatment types and soils in the following order: Ca‐treated > Al‐treated ≥ untreated > Fe‐treated > control. Within each treatment, Bray‐1 P decreased between 1 d and 1 to 2 wk and then gradually increased for up to 3 mo (Soils II and III) or 6 mo (Soil I). Application of Al‐ or Fe‐treated manure decreased P solubility with the effect being more pronounced in soils with high background P. Since the application of Ca‐treated manure increased both WEP and Bray‐1 P, it should be recommended for soils where the objective is to increase P availability. Several years of P input through fertilizer and manure contributed mainly to aluminum‐bound phosphorus (Al‐P) and to a lesser degree to other fractions. Only soluble and loosely bound P (all soils) and Al‐P (Soil I) exhibited treatment‐type effects after receiving chemically treated manure. The study results will help bridge the gap between our knowledge of chemical treatment systems for animal manure and the ultimate fate of P when the treated manure is land‐applied.
Influence of Phytase Addition to Poultry Diets on Phosphorus Forms and Solubility in Litters and Amended Soils
Authors: Maguire R. O. , Sims J. T. , Saylor W. W. , Turner B. L. , Angel R. , Applegate T. J.
Published: June 2010

Diet modification to decrease phosphorus (P) concentration in animal feeds and manures can reduce surpluses of manure P in areas of intensive animal production. We generated turkey and broiler litters from two and three flock trials, respectively, using diets that ranged from “high” to “low” in non‐phytate phosphorus (NPP) and some of which contained feed additives such as phytase. Phosphorus forms in selected litters were analyzed by sequential chemical fractionation and solution 31P nuclear magnetic resonance (NMR) spectroscopy. Selected litters were also incubated with four contrasting soils. Reducing dietary NPP and using phytase decreased total P in litters by up to 38%. Water‐soluble phosphorus (WSP) in litters was decreased 21 to 44% by feeding NPP closer to animal requirement, but was not affected by phytase addition. Solution 31P NMR spectroscopy showed that feeding NPP closer to requirement decreased orthophosphate in litters by an average of 38% and that adding phytase to feed did not increase the concentration of orthophosphate in litters. Phytase also decreased phytate P in litters by 25 to 38%, demonstrating that it increases phytate P hydrolysis. Incorporation of litters with soils at the same total P rate increased WSP in soils relative to the control; this increase was correlated to soluble P added with litters at 5 d, but not by 29 d. Changes in soil Mehlich‐3 phosphorus (M3‐P) were related to total P added in litter, rather than soluble P. We conclude that feeding NPP closer to requirement and using feed additives such as phytase decrease total P concentrations in litters, while having little effect on P solubility in litters and amended soils.
Phosphorus Composition of Manure from Swine Fed Low‐Phytate Grains
Authors: Leytem April B. , Turner Benjamin L. , Thacker P. A.
Published: June 2010

Including low‐phytic‐acid grains in swine diets can reduce P concentrations in manure, but the influence on manure P composition is relatively unknown. To address this we analyzed manure from swine fed one of four barley (Hordeum vulgare L.) varieties. The barley types consisted of wild‐type barley (CDC bold, normal barley diet) and three low‐phytic‐acid mutant barleys that contained similar amounts of total P but less phytic acid. The phytic acid concentrations in the mutant barleys were reduced by 32% (M422), 59% (M635), and 97% (M955) compared with that in the wild‐type barley, respectively. Phosphorus concentrations were approximately one‐third less in manures from animals fed low‐phytic‐acid barleys compared with those fed the wild‐type variety. Phytic acid constituted up to 55% of the P in feed, but only trace concentrations were detected in NaOH–EDTA extracts of all manures by solution 31P nuclear magnetic resonance (NMR) spectroscopy. Phosphate was the major P fraction in the manures (86–94% extracted P), with small concentrations of pyrophosphate and simple phosphate monoesters also present. The latter originated mainly from the hydrolysis of phospholipids during extraction and analysis. These results suggest that phytic acid is hydrolyzed in swine, possibly in the hind gut by intestinal microflora before being excreted in feces, even though the animals have little phytase activity in the gut and derive little nutritional benefit from phytate P. We conclude that feeding low‐phytic‐acid grains reduces total manure P concentrations and the manure P is no more soluble than P generated from normal barley diets.
Sustainable Land Application
Authors: O'Connor G. A. , Elliott H. A. , Basta N. T. , Bastian R. K. , Pierzynski G. M. , Sims R. C. , Smith J. E.
Published: June 2010

Man has land‐applied societal nonhazardous wastes for centuries as a means of disposal and to improve the soil via the recycling of nutrients and the addition of organic matter. Nonhazardous wastes include a vast array of materials, including manures, biosolids, composts, wastewater effluents, food‐processing wastes, industrial by‐products; these are collectively referred to herein as residuals. Because of economic restraints and environmental concerns about land‐filling and incineration, interest in land application continues to grow. A major lesson that has been learned, however, is that the traditional definition of land application that emphasizes applying residuals to land in a manner that protects human and animal health, safeguards soil and water resources, and maintains long‐term ecosystem quality is incomplete unless the earning of public trust in the practices is included. This overview provides an introduction to a subset of papers and posters presented at the conference, “Sustainable Land Application,” held in Orlando, FL, in January 2004. The USEPA, USDA, and multiple national and state organizations with interest in, and/or responsibilities for, ensuring the sustainability of the practice sponsored the conference. The overriding conference objectives were to highlight significant developments in land treatment theory and practice, and to identify future research needs to address critical gaps in the knowledge base that must be addressed to ensure sustainable land application of residuals.
Beneficial Reuse and Sustainability: The Fate of Organic Compounds in Land‐Applied Waste
Authors: Overcash Michael , Sims Ronald C. , Sims Judith L. , Nieman J. Karl C.
Published: June 2010

Land application systems, also referred to as beneficial reuse systems, are engineered systems that have defined and permitted application areas based on site and waste characteristics to determine the land area size requirement. These terrestrial systems have orders of magnitude greater microbial capability and residence time to achieve decomposition and assimilation compared with aquatic systems. In this paper we focus on current information and information needs related to terrestrial fate pathways in land treatment systems. Attention is given to conventional organic chemicals as well as new estrogenic and pharmaceutical chemicals of commerce. Specific terrestrial fate pathways addressed include: decomposition, bound residue formation, leaching, runoff, and crop uptake. Molecular decomposition and formation of bound residues provide the basis for the design and regulation of land treatment systems. These mechanisms allow for assimilation of wastes and nondegradation of the environment and accomplish the goal of sustainable land use. Bound residues that are biologically produced are relatively immobile, degrade at rates similar to natural soil materials, and should present a significantly reduced risk to the environment as opposed to parent contaminants. With regard to leaching and runoff pathways, no comprehensive summary or mathematical model of organic chemical migration from land treatment systems has been developed. For the crop uptake pathway, a critical need exists to develop information for nonagricultural chemicals and to address full‐scale performance and monitoring at more land application sites. The limited technology choices for treatment of biosolids, liquids, and other wastes implies that acceptance of some risks and occurrence of some benefits will continue to characterize land application practices that contribute directly to the goal of beneficial reuse and sustainability.
Processes for Managing Pathogens
Authors: Godfree Alan , Farrell Joseph
Published: June 2010

Wastewater contains human, animal, and plant pathogens capable of causing viral, bacterial, or parasitic infections. There are several routes whereby sewage pathogens may affect human health, including direct contact, contamination of food crops, zoonoses, and vectors. The range and numbers of pathogens in municipal wastewater vary with the level of endemic disease in the community, discharges from commercial activities, and seasonal factors. Regulations to control pathogen risk in the United States and Europe arising from land application of biosolids are based on the concept of multiple barriers to the prevention of transmission. The barriers are (i) treatment to reduce pathogen content and vector attraction, (ii) restrictions on crops grown on land to which biosolids have been applied, and (iii) minimum intervals following application and grazing or harvesting. Wastewater treatment reduces number of pathogens in the wastewater by concentrating them with the solids in the sludge. Although some treatment processes are designed specifically to inactivate pathogens, many are not, and the actual mechanisms of microbial inactivation are not fully understood for all processes. Vector attraction is reduced by stabilization (reduction of readily biodegradable material) and/or incorporation immediately following application. Concerns about health risks have renewed interest in the effects of treatment (on pathogens) and advanced treatment methods, and work performed in the United States suggests that Class A pathogen reduction can be achieved less expensively than previously thought. Effective pathogen risk management requires control to the complete chain of sludge treatment, biosolids handling and application, and post‐application activities. This may be achieved by adherence to quality management systems based on hazard analysis critical control point (HACCP) principles.
The Evolving Science of Chemical Risk Assessment for Land‐Applied Biosolids
Authors: Schoof Rosalind A. , Houkal Dana
Published: June 2010

Biosolids, effluents, and manures are widely applied to agricultural land and other land with varying degrees of pretreatment or control. Regulations governing land application of biosolids take several broad forms in different countries, including limitations based on rates that do not lead to increases in background chemical concentrations or risk assessment approaches such as those used in the United States. Risk assessment is a process that is inherently limited by currently available information and practices, and consequently, risk‐based land application limits must be reevaluated periodically. For complex mixtures such as biosolids, three principal categories of information will be affected by changing practices and scientific advances: (i) chemical constituents present in the material, (ii) the nature of expected exposures, and (iii) toxicity of the chemical constituents. New analytical methods and lower detection limits will affect chemical identification in wastes. Approaches to exposure assessment, such as increasing emphasis on probabilistic analyses, will continue to evolve, and exposure assumptions will change as new studies provide better data on factors such as soil ingestion, plant uptake of chemicals, and bioavailability of chemicals in soil. Similarly, toxicity assessments will be updated as new studies are conducted. The evolving science over the past decade is illustrated by comparing approaches used by the USEPA to assess human health and ecological risks for the Part 503 rule compared with the more recent evaluation of dioxins and related compounds in biosolids. While risks of chemicals in land‐applied biosolids and other residuals need to be periodically reevaluated, such reevaluations may take forms other than full risk assessments.
Atmospheric Supply of Trace Elements Studied by Peat Samples from Ombrotrophic Bogs
Authors: Steinnes E. , Hvatum O. Ø. , B⊘lviken B. , Varskog P.
Published: June 2010

Concentrations of Fe and 12 trace elements in peat from ombrotrophic bogs were used to estimate the atmospheric deposition of these elements on a temporal and spatial scale. Peat samples were collected at 21 different sites in Norway encompassing large geographical differences in marine influence and air pollution. The study demonstrates that surface peat is an excellent medium to study geographical differences in heavy metal deposition, provided that effects of the surface plant cover are properly considered. Long‐range atmospheric transport of pollutants is the main source for As, Cd, Pb, Sb, and Zn, and to a lesser extent for Cu and Se. Biogenic emissions from the ocean appear to be the main source of Se to the peat. The metals Co, Cr, Fe, and Ni are mainly associated with windblown local soil dust. Surface enrichment of Mn, and in part Zn, is mainly caused by nutrient circulation between the surface peat and vascular plants growing on it. Deposition of marine salts appears to be the main reason for lower Mn concentrations in the peat near the coast.
Fracture‐Controlled Nitrate and Atrazine Transport in Four Iowa Till Units
Authors: Helmke Martin F. , Simpkins William W. , Horton Robert
Published: June 2010

Fractures in till may provide pathways for agricultural chemicals to contaminate aquifers and surface waters. This study was conducted to quantify the influence of fractures on solute fate and transport using three conservative and two nonconservative tracers. The conservative tracers were potassium bromide (KBr), pentafluorobenzoic acid (PFBA), and 1,4‐piperazinediethanesulfonic acid disodium salt (PIPES); the nonconservative tracers were nitrate and atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine]. Three sites in Iowa were investigated, including four late Wisconsinan and Pre‐Illinoian tills. Laboratory tracer experiments were conducted using eight large (0.4–0.45 m long by 0.43 m in diameter), undisturbed columns of till collected from depths of 1 to 28 m. The tills were densely fractured, with fracture spacing ranging from 3.8 to 10.4 cm. First arrival velocities of Br− ranged from 0.004 to 64.8 m d−1, 10 to 100 times faster than predicted for unfractured media. Nitrate behaved as a conservative tracer in weathered till columns, but degraded during experiments using deeper tills. Sorption caused retardation of atrazine in the shallowest four columns. Atrazine degradation occurred in deeper columns as demonstrated by deviations between atrazine and the conservative tracers. Mobile–immobile model (MIM) simulations estimated first‐order exchange coefficients (α) ranging from 1 × 10−8 to 1.7 × 10−2 s−1, sorption coefficients (Kd) for atrazine ranging from 2.6 × 10−5 to 1 × 10−3 m3 kg−1, and degradation half‐lives ranging from 0.24 to 67 d (nitrate) and 1.6 to 277 d (atrazine). This study suggests that aquifers and surface waters associated with thin, fractured till units may be vulnerable to contamination, yet deeper aquifers may be protected by these materials due to increased residence times provided by matrix diffusion.
A Laboratory Study of Bacteria‐Facilitated Cadmium Transport in Alluvial Gravel Aquifer Media
Authors: Pang L. , Close M. E. , Noonan M. J. , Flintoft M. J. , van den Brink P.
Published: June 2010

Colloids, including bacteria, can dramatically accelerate the transport of heavy metals in ground water. Batch and column experiments were conducted to investigate adsorption of cadmium (Cd) onto Bacillus subtilis spores or Escherichia coli vegetative cells and Cd transport in alluvial gravel aquifer media in the presence of these bacteria. Results of the batch experiments showed that adsorption of Cd onto the bacteria was (i) positively related to solution pH, bacterial concentration, and negative surface charge, but inversely related to Cd concentration and (ii) a rate‐limited nonlinear process, but adsorption onto E. coli was much less. For column influent Cd concentrations of about 4 mg/L and bacterial concentrations of ≥105 colony‐forming units (cfu)/mL, there was a significant increase in total Cd effluent concentrations. In comparison with controls that did not have bacteria‐facilitated transport, Cd traveled 17 to 20 times faster when it traveled with mobile bacteria. However, Cd traveled mostly 2 to 3 times slower during the desorption phase under the influence of bacteria retained in the column. The difference between total and dissolved Cd concentrations was significant during Cd cotransport with B. subtilis spores, but this concentration difference was very small during Cd cotransport with E. coli, suggesting an adsorption‐dominant mechanism during Cd cotransport with the spores and the possibility of Cd chelation by the dissolved membrane vesicles secreted from E. coli cell walls. Bacteria‐facilitated transport of heavy metals may pose a threat to ground water quality in sites such as landfills and following land disposal of industrial and domestic effluent and sludge.
Effects of Sedimentation on Soil Nutrient Dynamics in Riparian Forests
Authors: Lockaby B. G. , Governo R. , Schilling E. , Cavalcanti G. , Hartsfield C.
Published: June 2010

The influence of sedimentation rates on biogeochemistry of riparian forests was studied near ephemeral streams at Fort Benning, GA. Upper reaches of seven ephemeral streams had received varying rates of sedimentation stemming from erosion along unpaved roadways at the military installation. Two reference catchments were also included in the study. Decomposition of foliar litter, microbial C and N, N mineralization, and arthropod populations were compared within and among catchments. Rates of sedimentation over the past 25 yr ranged from 0 in references to 4.0 cm yr−1Decomposition rates declined exponentially with sedimentation rates as low as 0.20 to 0.32 cm yr−1and appeared to reach an equilibrium at a sedimentation rate of 0.5 cm yr−1Nitrogen mineralization and microbial C and N followed the same trend. Sedimentation had no discernible effect on arthropod populations. These data suggest that biogeochemical cycles may be altered by sedimentation rates that commonly occur in some floodplain forests.
Assessment of Denitrification Gaseous End‐Products in the Soil Profile under Two Water Table Management Practices Using Repeated Measures Analysis
Authors: Elmi Abdirashid A. , Astatkie Tess , Madramootoo Chandra , Gordon Robert , Burton David
Published: June 2010

The denitrification process and nitrous oxide (N2O) production in the soil profile are poorly documented because most research into denitrification has concentrated on the upper soil layer (0–0.15 m). This study, undertaken during the 1999 and 2000 growing seasons, was designed to examine the effects of water table management (WTM), nitrogen (N) application rate, and depth (0.15, 0.30, and 0.45 m) on soil denitrification end‐products (N2O and N2) from a corn (Zea mays L.) field. Water table management treatments were free drainage (FD) with open drains and subirrigation (SI) with a target water table depth of 0.6 m. Fertility treatments (ammonium nitrate) were 120 kg N ha−1 (N120) and 200 kg N ha−1 (N200). During both growing seasons greater denitrification rates were measured in SI than in FD, particularly in the surface soil (0–0.15 m) and at the intermediate (0.15–0.30 m) soil depths under N200 treatment. Greater denitrification rates under the SI treatment, however, were not accompanied with greater N2O production. The decrease in N2O production under SI was probably caused by a more complete reduction of N2O to N2, which resulted in lower N2O to (N2O + N2) ratios. Denitrification rate, N2O production and N2O to (N2O + N2) ratios were only minimally affected by N treatments, irrespective of sampling date and soil depth. Overall, half of the denitrification occurred at the 0.15‐ to 0.30‐ and 0.30‐ to 0.45‐m soil layers, and under SI, regardless of fertility treatment level. Consequently, sampling of the 0‐ to 0.15‐m soil layer alone may not give an accurate estimation of denitrification losses under SI practice.
Copper Availability in Seven Israeli Soils Incubated with and without Biosolids
Authors: Oliver I. W. , Hass A. , Merrington G. , Fine P. , McLaughlin M. J.
Published: June 2010

Land application is becoming a preferred option for disposal of sewage sludge (biosolids) from wastewater treatment plants. However, it creates potential risks due to the heavy metal contents of these materials, with copper (Cu) being of chief concern. The long‐term fate of biosolid metals applied to agricultural soils is not well understood, particularly in the soils of the Middle East. This investigation was conducted to determine whether the availability of Cu changes with time in biosolid‐amended and nonamended soils from Israel. Seven soils, typifying the span of properties and formation environments encountered in Israel, were incubated with and without biosolids for 7 yr, and changes in organic carbon (OC) content and labile Cu concentration were determined. Isotopic exchange techniques, using64Cu, and ion activity measurements, using a Cu2+ion selective electrode, revealed that the available Cu concentration remained relatively low and stable over the 7‐yr incubation. This was despite substantial reductions in OC. This study shows that, with regard to Cu, application of such biosolids to these soils at rates of up to 250 Mg ha−1does not pose a threat to the environment in the short to medium term.
Characterization of the Pesticide Chlordane in Estuarine River Sediments
Authors: Ouyang Y. , Ou L.‐T. , Sigua G. C.
Published: June 2010

Sediments are increasingly recognized as both carrier and potential source of contaminants in aquatic environments. This study investigated the characteristics and spatial distribution of total chlordane and its three most abundant compounds, including α‐chlordane, γ‐chlordane, and trans‐nonachlor, in sediments from the Cedar and Ortega rivers, Florida, USA, using geographic information system (GIS)‐based kriging analyses and field measurements. Kriging analysis showed that two areas, one from the Cedar River area and the other from the northern end of the Ortega River area, were contaminated. The maximum concentrations of total chlordane, γ‐chlordane, α‐chlordane, and trans‐nonachlor in the sediments were, respectively, 101.8, 20.1, 26.3, and 19.2 μg/kg. A plot of total organic carbon (TOC)‐normalized chlordane concentrations showed that effects of grain size on sediment chlordane contamination were negligible. A principal axis analysis further revealed that a linear correlation existed between α‐chlordane and total chlordane as well as between γ‐chlordane and total chlordane, whereas no correlation existed between trans‐nonachlor and total chlordane. Comparison of total chlordane concentration with Florida Sediment Assessment Guidelines showed that the Cedar River and the northern end of the Ortega River had total chlordane concentrations above the probable effect level (4.79 μg/kg), which could pose a potential risk to aquatic life.