bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Peroxide on Neutralization‐Potential Values of Siderite and Other Carbonate Minerals
Authors: Jambor J. L. , Dutrizac J. E. , Raudsepp M. , Groat L. A. 
Published: June 2010

ABSTRACTTo assess quantitatively the effect of peroxide addition to standard static tests of the neutralization potential (NP) of mine wastes, 10 specimens of carbonate minerals, including five of siderite (FeCO3) and two of rhodochrosite (MnCO3), were analyzed by electron microprobe. The compositions of the siderite span a range from 60 to 86 mol % Fe. Tests of NP for the siderite diluted with 80% (w/w) kaolinite gave values of 647 to 737 kg CaCO3 equivalent per Mg for determinations by the standard Sobek method. However, if it is assumed that the ferrous carbonate component of the mineral does not contribute to NP in field situations because oxidation of Fe(II) to Fe(III) and the subsequent hydrolysis of Fe(III) leads to the release of an equivalent amount of acid, then the calculated NP for the samples ranges from 110 to 390 kg CaCO3 equivalent per Mg. Two different methods involving the addition of peroxide to the test solutions were successful in bringing the measured NP values closer to the theoretical ones. By contrast, the tests with rhodochrosite indicated the Mn(II) to be stable. For long‐term environmental planning, especially for wastes from metalliferous sulfide‐poor deposits in which gradual dissolution of silicate and aluminosilicate minerals may be involved in attenuating the acidity, consideration in the overall NP budget needs to be given to the ferrous iron content of those minerals. The presence of Fe2+–bearing minerals, especially carbonates, in tested mine‐waste materials may lead to overestimated Sobek NP values, thus increasing the risk of poor‐quality drainage and the need for costly remediation.
Effects of Static vs. Tidal Hydrology on Pollutant Transformation in Wetland Sediments
Authors: Catallo W. James , Junk Thomas 
Published: June 2010

ABSTRACTThis work addressed effects of hydrology on biogeochemical processes relevant to pollutant chemical transformation in wetland sediments. Microcosms were designed to impose three hydrologic conditions on salt marsh sediments: (i) drained–oxidized redox potenial (Eh); (ii) flooded–reduced Eh and, (iii) diurnal tide–oscillating Eh. The test chemicals were N‐ and/or S‐heterocycles (NSHs) including quinoxaline (1,4‐benzodiazine), 2‐methylquinoxaline(2‐methyl‐1,4‐benzodiazine), 2,3‐dimethylquinoxalinen (2,3‐dimethyl‐1,4,benzodiazine), phenazine (2,3,5,6‐dibenzo‐1,4‐diazine), acridine (2,3,5,6‐dibenzopyridine), dibenzothiophene (2,3,5‐dibenzothiophene), phenothiazine (dibenzo‐1,4‐thiazine), and phenanthridine (2,3‐benzoisoquinoline). Biogeochemical processes reflected the hydrologic conditions in ways analogous to field settings, e.g., Eh characteristics were drastically different: static (flooded and drained) systems had reduced (μ = −428 mV ± 57) and oxidized (μ = +73 mV ± 32) values, respectively, with no evidence of periodic variation while the tidal systems exhibited regularly oscillating Eh (amplitudes 40–250 mV). Sediment trace gases also corresponded to the Eh, with the major species detected being CO2 and H2O (drained, tidal) vs. CO2 + H2O + sulfides + methane (flooded). The NSH transformation rates were different in each hydrologic regime and decreased as follows: tidal ≥ drained ≫ flooded. These results indicated that there were subtle differences in NSH processing in drained and tidal systems, but both of these systems transformed NSHs faster and to lower levels than flooded sediments. These data suggest that in situ remediation options that preserve wetland integrity and tidal hydrology can be as or more effective than static conditions that obtain in approaches such as impoundment and excavation–upland placement.
Nitrification and Denitrification Rates of Everglades Wetland Soils along a Phosphorus‐Impacted Gradient
Authors: White John R. , Reddy K. R. 
Published: June 2010

ABSTRACTLittle information is available on the effect of phosphorus (P) enrichment on nitrogen (N) biogeochemical cycling in wetland soil. Of particular importance are the coupled nitrification–denitrification reactions that regulate the microbially mediated loss of N from wetland systems. Soils from the northern Florida Everglades have been affected by P loading from surface waters over the past 40 years. Elevated P levels have been show to have an effect on the size and activity of the microbial pool and a decrease in the N to P ratio of the microbial biomass. The objective of the study was to determine if P enrichment in soils affected microbial activities related to nitrification and denitrification in these flooded, peat soils. Potential nitrification rates of soil and detritus were determined using constantly stirred reactors under aerobic conditions while denitrification rates were determined from anaerobic incubations of slurry. Nitrification rates showed two distinct linear phases, a slower initial rate, signifying activity of nitrifiers present, followed by a sharp increase in the NH4+conversion rate indicative of maximum potential rates. Initial rates of nitrification were highest in the surficial detrital layer decreasing with soil depth and did not correlate to soil total P. The potential rates of nitrification were 13 times greater than the initial rates. Potential denitrification rates were highest in the detritus and 0‐ to 10‐cm soil interval with significantly lower values in the 10‐ to 30‐cm soil interval, significantly correlated to total P of the soil. A significant (P< 0.01) relationship was seen between potential denitrification rates and soil total P suggesting an increased rate of N removal from P‐enriched regions of the northern Everglades.
Ammonia Volatilization from Marsh–Pond–Marsh Constructed Wetlands Treating Swine Wastewater
Authors: Poach M. E. , Hunt P. G. , Reddy G. B. , Stone K. C. , Matheny T. A. , Johnson M. H. , Sadler E. J. 
Published: June 2010

ABSTRACTAmmonia (NH3) volatilization is an undesirable mechanism for the removal of nitrogen (N) from wastewater treatment wetlands. To minimize the potential for NH3 volatilization, it is important to determine how wetland design affects NH3 volatilization. The objective of this research was to determine how the presence of a pond section affects NH3 volatilization from constructed wetlands treating wastewater from a confined swine operation. Wastewater was added at different N loads to six constructed wetlands of the marsh–pond–marsh design that were located in Greensboro, North Carolina, USA. A large enclosure was used to measure NH3 volatilization from the marsh and pond sections of each wetland in July and August of 2001. Ammonia volatilized from marsh and pond sections at rates ranging from 5 to 102 mg NH3–N m−2 h−1 Pond sections exhibited a significantly greater increase in the rate of NH3 volatilization (p < 0.0001) than did either marsh section as N load increased. At N loads greater than 15 kg ha−1 d−1, NH3 volatilization accounted for 23 to 36% of the N load. Furthermore, NH3 volatilization was the dominant (54–79%) N removal mechanism at N loads greater than 15 kg ha−1 d−1 Without the pond sections, NH3 volatilization would have been a minor contributor (less than 12%) to the N balance of these wetlands. To minimize NH3 volatilization, continuous marsh systems should be preferred over marsh–pond–marsh systems for the treatment of wastewater from confined animal operations.
Biodegradation of Polycyclic Aromatic Hydrocarbons in Oil‐Contaminated Beach Sediments Treated with Nutrient Amendments
Authors: Xu Ran , Obbard Jeffrey P. 
Published: June 2010

ABSTRACTMicrobial biodegradation of polycyclic aromatic hydrocarbons (PAHs) during the process of bioremediation can be constrained by lack of nutrients, low bioavailability of the contaminants, or scarcity of PAH‐biodegrading microorganisms. This study focused on addressing the limitation of nutrient availability for PAH biodegradation in oil‐contaminated beach sediments. In our previous study, three nutrient sources including inorganic soluble nutrients, the slow‐release fertilizer Osmocote (Os; Scotts, Marysville, OH) and Inipol EAP‐22 (Ip; ATOFINA Chemicals, Philadelphia, PA), as well as their combinations, were applied to beach sediments contaminated with an Arabian light crude oil. Osmocote was the most effective nutrient source for aliphatic biodegradation. This study presents data on PAH biodegradation in the oil‐spiked beach sediments amended with the three nutrients. Biodegradation of total target PAHs (two‐ to six‐ring) in all treatments followed a first‐order biodegradation model. The biodegradation rates of total target PAHs in the sediments treated with Os were significantly higher than those without. On Day 45, approximately 9.3% of total target PAHs remained in the sediments amended with Os alone, significantly lower than the 54.2 to 58.0% remaining in sediment treatments without Os. Amendment with Inipol or soluble nutrients alone, or in combination, did not stimulate biodegradation rates of PAHs with a ring number higher than 2. The slow‐release fertilizer (Os) is therefore recommended as an effective nutrient amendment for intrinsic biodegradation of PAHs in oil‐contaminated beach sediments.
Adsorption and Desorption of Metolachlor and Metolachlor Metabolites in Vegetated Filter Strip and Cultivated Soil
Authors: Krutz L. J. , Senseman S. A. , McInnes K. J. , Hoffman D. W. , Tierney D. P. 
Published: June 2010

ABSTRACTPrevious studies have indicated that dissolved‐phase metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(methoxy‐1‐methylethyl)acetamide] transported in surface runoff is retained by vegetative filter strips to a greater degree than either metolachlor oxanilic acid [2‐[(2‐ethyl‐6‐methylphenyl)(2‐methoxy‐1‐methylethyl)amino]‐2‐oxoacetic acid] (OA) or metolachlor ethanesulfonic acid [2‐[(2‐ethyl‐6‐methylphenyl)(2‐methoxy‐1‐methylethyl‐1)amino]‐2‐oxoethanesulfonic acid] (ESA), two primary metabolites of metolachlor. Adsorption–desorption of ESA and OA in vegetated filter strip soil (VFSS) has not been evaluated, yet these data are required to assess the mobility of these compounds in VFSS. The objective of this experiment was to compare metolachlor, ESA, and OA adsorption and desorption parameters between VFSS and cultivated soil (CS). Adsorption and desorption isotherms were determined using the batch equilibrium procedure. With the exception of a 1.7‐fold increase in organic carbon content in the VFSS, the evaluated chemical and physical properties of the soils were similar. Sorption coefficients for metolachlor were 88% higher in VFSS than in CS. In contrast, sorption coefficients for ESA and OA were not different between soils. Relative to metolachlor, sorption coefficients for ESA and OA were at least 79% lower in both soils. Metolachlor desorption coefficients were 59% higher in the VFSS than in the CS. Desorption coefficients for ESA and OA were not different between soils. Relative to metolachlor, desorption coefficients for ESA and OA were at least 66% lower in both soils. These data indicate that the mobility of ESA and OA will be greater than metolachlor in both soils. However, higher organic carbon content in VFSS relative to CS may limit the subsequent transport of metolachlor from the vegetated filter strip.
Cover Cropping to Reduce Nitrate Loss through Subsurface Drainage in the Northern U.S. Corn Belt
Authors: Strock J. S. , Porter P. M. , Russelle M. P. 
Published: June 2010

ABSTRACTDespite the use of best management practices for nitrogen (N) application rate and timing, significant losses of nitrate nitrogen NO−3–N in drainage discharge continue to occur from row crop cropping systems. Our objective was to determine whether a autumn‐seeded winter rye (Secale cereale L.) cover crop following corn (Zea mays L.) would reduce NO−3–N losses through subsurface tile drainage in a corn–soybean [Glycine max (L.) Merr.] cropping system in the northern Corn Belt (USA) in a moderately well‐drained soil. Both phases of the corn–soybean rotation, with and without the winter rye cover crop following corn, were established in 1998 in a Normania clay loam (fine‐loamy, mixed, mesic Aquic Haplustoll) soil at Lamberton, MN. Cover cropping did not affect subsequent soybean yield, but reduced drainage discharge, flow‐weighted mean nitrate concentration (FWMNC), and NO−3–N loss relative to winter fallow, although the magnitude of the effect varied considerably with annual precipitation. Three‐year average drainage discharge was lower with a winter rye cover crop than without (p = 0.06). Over three years, subsurface tile‐drainage discharge was reduced 11% and NO−3–N loss was reduced 13% for a corn–soybean cropping system with a rye cover crop following corn than with no rye cover crop. We estimate that establishment of a winter rye cover crop after corn will be successful in one of four years in southwestern Minnesota. Cover cropping with rye has the potential to be an effective management tool for reducing NO−3–N loss from subsurface drainage discharge despite challenges to establishment and spring growth in the north‐central USA.
Sequence‐Based Source Tracking of Escherichia coli Based on Genetic Diversity of β‐Glucuronidase
Authors: Ram Jeffrey L. , Ritchie Raquel P. , Fang Jianwen , Gonzales Felicitas S. , Selegean James P. 
Published: June 2010

ABSTRACTHigh levels of fecal bacteria are a concern for recreational waters; however, the source of contamination is often unknown. This study investigated whether direct sequencing of a bacterial gene could be utilized for detecting genetic differences between bacterial strains for microbial source tracking. A 525‐nucleotide segment of the gene for β‐glucuronidase (uidA) was sequenced in 941 Escherichia coli isolates from the Clinton River–Lake St. Clair watershed, 182 E. coli isolates from human and animal feces, and 34 E. coli isolates from a combined sewer. Environmental isolates exhibited 114 alleles in 11 groups on a genetic tree. Frequency of strains from different genetic groups differed significantly (p < 0.03) between upstream reaches (Bear Creek–Red Run), downstream reaches, and Lake St. Clair beaches. Fecal E. coli uidA sequences exhibited 81 alleles that overlapped with the environmental set. An algorithm to assign alleles to different host sources averaged approximately 75% correct classification with the fecal data set. Using the same algorithm, the percent of environmental isolates assignable to humans decreased significantly between Bear Creek–Red Run (30 ± 3%) and the beaches (17 ± 2%) (p < 0.05). Birds accounted for approximately 50% of assignable environmental isolates. For combined sewer isolates, the same algorithm assigned 51% to humans. These experiments demonstrate differences in the frequency of different E. coli strains at different locations in a watershed, and provide a “proof in principle” that sequence‐based data can be used for microbial source tracking.
Feasibility and Costs of Phosphorus Application Limits on 39 U.S. Swine Operations
Authors: Lory John A. , Massey Raymond E. , Zulovich Joseph M. , Hoehne John A. , Schmidt Amy M. , Carlson Marcia S. , Fulhage Charles D. 
Published: June 2010

ABSTRACTConcerns about manure P and water quality have prompted new regulations imposing P limits on land application of manure. Previous research established that P limits increase land needs for animal feeding operations. We evaluated the effect of N, annual P, and rotation P limits on the feasibility of manure management. A mechanistic model characterized manure management practices on 39 swine operations (20 unagitated lagoon and 19 slurry operations) in five states (Iowa, Missouri, North Carolina, Oklahoma, and Pennsylvania). Extensive information collected from each operation was used to determine effects of manure storage type, ownership structure, and application limits on attributes of manure management. Phosphorus limits had substantially greater effect on slurry operations, increasing land needs 250% (0.3 hectares per animal unit [AU]) and time for manure application 24% (2.5 min AU−1) for rotation P limits and 41% (4.4 min AU−1) for annual P limits. Annual P limits were infeasible for current land application equipment on two operations and had the greatest effect on time and costs because they required all but three slurry operations to reduce discharge rate. We recommend implementing rotation P limits (not to exceed crop N need) to minimize time effects, allow most farmers to use their current manure application methods, and allow manure to fulfill crop N and P needs in the year of application. Phosphorus limits increased potential manure value but would require slurry operations to recover at least 61% of manure value through manure sales. Phosphorus limits are likely to shape the U.S. swine industry through differential effects on the various sectors of the swine industry.
Nitrate Removal in Riparian Wetlands
Authors: Rutherford J. C. , Nguyen M. L. 
Published: June 2010

ABSTRACTRiparian wetlands containing springs are thought to be ineffective at removing nitrate because contact times between the upwelled ground water and the underlying microbially active soils are short. Tracer experiments using lithium bromide (LiBr) and nitrate (NO3–N) injected at the surface were used to quantify residence times and NO3–N removal in a riparian swale characteristic of New Zealand hill‐country pasture. An experimental enclosure was used with collecting trays at the downstream end to measure flow and concentration, shallow wells to measure subsurface concentrations, and an array of logging conductivity probes to monitor tracer continuously. The majority of added tracer reached the outlet more slowly than could be explained by surface flow, but more quickly than could be explained by Darcy seepage flow. There was evidence from the wells of tracer diffusing vertically to a depth of at least 5 cm into the surface soil layer, which was permanently saturated and highly porous. During dry weather 24 ± 9% of added NO3–N was removed over a distance of 1.5 m largely by denitrification. The net uptake length coefficient for this wetland (K = 0.08 ± 0.03 m−1) is slightly higher than the range (K = 0.01–0.07 m−1) measured in a small stream channel infested with macrophytes. Nitrate removal is expected to decrease with increasing flow. Seepage flow is estimated to have removed only 7 ± 4% of the added NO3–N and we hypothesize that vertical diffusion substantially increases NO3–N removal in this type of wetland. Riparian wetlands with springs and surface flows should not be dismissed as having low NO3–N removal potential without checking whether there is significant vertical mixing.
In Situ Dynamics of Phosphorus in the Rhizosphere Solution of Five Species
Authors: Wang Z. Y. , Kelly J. M. , Kovar J. L. 
Published: June 2010

ABSTRACTRoot activity can modify the chemistry of the rhizosphere and alter phosphorus (P) availability and uptake. However, until recently, relatively little was known about the dynamics of soil solution P at the root surface because of our inability to measure in situ changes in solution P at the plant root. A mini‐rhizotron experiment with corn (Zea mays L. cv. Stine 2250), soybean [Glycine max (L.) Merr. cv. Pioneer 3563), cottonwood (Populus deltoids L.), smooth brome (Bromus inermis Leyss.), and switchgrass (Panicum virgatum L.) was conducted to measure the spatial and temporal dynamics of P in the rhizosphere solution of a fine silty, P‐rich calcareous soil (solid‐phase total P concentration = 62 mg kg−1, pH = 7.68) from western Iowa. Micro‐suction cups were used to collect samples of soil solution from defined segments of the rhizosphere, and capillary electrophoresis (CE) was used to determine the P concentration of the soil solution. At the end of 10 d, a decreasing P concentration gradient in soil solution toward the root was observed in corn, cottonwood, and smooth brome. No clear rhizosphere effect was observed for soybean and switchgrass. Statistical analysis indicated significantly lower solution P concentrations in the rhizospheres of corn (p = 0.05), cottonwood (p = 0.01), and smooth brome (p = 0.01) compared with bulk soil solution. Results indicate that P depletion from rhizosphere soil solution depends on plant species. Under the conditions of this study, corn, cottonwood, and smooth brome were more effective in depleting solution P than soybean and switchgrass.
Evaluation of Phosphorus Transport in Surface Runoff from Packed Soil Boxes
Authors: Kleinman Peter J. A. , Sharpley Andrew N. , Veith Tamie L. , Maguire Rory O. , Vadas Peter A. 
Published: June 2010

ABSTRACTEvaluation of phosphorus (P) management strategies to protect water quality has largely relied on research using simulated rainfall to generate runoff from either field plots or shallow boxes packed with soil. Runoff from unmanured, grassed field plots (1 m wide × 2 m long, 3–8% slope) and bare soil boxes (0.2 m wide and 1 m long, 3% slope) was compared using rainfall simulation (75 mm h−1) standardized by 30‐min runoff duration (rainfall averaged 55 mm for field plots and 41 mm for packed boxes). Packed boxes had lower infiltration (1.2 cm) and greater runoff (2.9 cm) and erosion (542 kg ha−1) than field plots (3.7 cm infiltration; 1.8 cm runoff; 149 kg ha−1 erosion), yielding greater total phosphorus (TP) losses in runoff. Despite these differences, regressions of dissolved reactive phosphorus (DRP) in runoff and Mehlich‐3 soil P were consistent between field plots and packed boxes reflecting similar buffering by soils and sediments. A second experiment compared manured boxes of 5‐ and 25‐cm depths to determine if variable hydrology based on box depth influenced P transport. Runoff properties did not differ significantly between box depths before or after broadcasting dairy, poultry, or swine manure (100 kg TP ha−1). Water‐extractable phosphorus (WEP) from manures dominated runoff P, and translocation of manure P into soil was consistent between box types. This study reveals the practical, but limited, comparability of field plot and soil box data, highlighting soil and sediment buffering in unamended soils and manure WEP in amended soils as dominant controls of DRP transport.
Runoff Phosphorus Losses as Related to Phosphorus Source, Application Method, and Application Rate on a Piedmont Soil
Authors: Tarkalson David D. , Mikkelsen Robert L. 
Published: June 2010

ABSTRACTLand application of animal manures and fertilizers has resulted in an increased potential for excessive P losses in runoff to nutrient‐sensitive surface waters. The purpose of this research was to measure P losses in runoff from a bare Piedmont soil in the southeastern United States receiving broiler litter or inorganic P fertilizer either incorporated or surface‐applied at varying P application rates (inorganic P, 0–110 kg P ha−1; broiler litter, 0–82 kg P ha−1). Rainfall simulation was applied at a rate of 76 mm h−1 Runoff samples were collected at 5‐min intervals for 30 min and analyzed for reactive phosphorus (RP), algal‐available phosphorus (AAP), and total phosphorus (TP). Incorporation of both P sources resulted in P losses not significantly different than the unfertilized control at all application rates. Incorporation of broiler litter decreased flow‐weighted concentration of RP in runoff by 97% and mass loss of TP in runoff by 88% compared with surface application. Surface application of broiler litter resulted in runoff containing between 2.3 and 21.8 mg RP L−1 for application rates of 8 to 82 kg P ha−1, respectively. Mass loss of TP in runoff from surface‐applied broiler litter ranged from 1.3 to 8.5 kg P ha−1 over the same application rates. Flow‐weighted concentrations of RP and mass losses of TP in runoff were not related to application rate when inorganic P fertilizer was applied to the soil surface. Results for this study can be used by P loss assessment tools to fine‐tune P source, application rate, and application method site factors, and to estimate extreme‐case P loss from cropland receiving broiler litter and inorganic P fertilizers.