bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitrogen and Phosphorus Flux Rates from Sediment in the Lower St. Johns River Estuary
Authors: Malecki Lynette M. , White John R. , Reddy K. R. 
Published: June 2010

ABSTRACTInternal cycling of nutrients from the sediment and water column can be an important contribution to the total nutrient load of an aquatic ecosystem. Our objective was to estimate the internal nutrient loading of the Lower St. Johns River (LSJR). Dissolved reactive phosphorus (DRP) and ammonium (NH4–N) flux from sediments were measured under aerobic and anaerobic water column conditions using intact cores, to estimate the overall contribution of the sediments to P and N loading to the LSJR. The DRP flux under aerobic water column conditions averaged 0.13 mg m−2 d−1, approximately 37 times lower than that under anaerobic conditions (4.77 mg m−2 d−1). The average NH4–N released from the anaerobic cores (18.03 mg m−2 d−1) was also significantly greater than in the aerobic cores for all sites and seasons, indicating the strong relationship between nutrient fluxes and oxygen availability in the water column. The mean annual internal DRP load was estimated to be 330 metric tons (Mg) yr−1, 21% of the total P load to the river, while the mean annual internal load of NH4–N was determined to be 2066 Mg yr−1, 28% of the total N load to the LSJR estuary. As water resource managers reduce external loading to the LSJR the frequency of anaerobic events should decline, thereby reducing nutrient fluxes from the sediment to the water column, reducing the internal loading of DRP and NH4–N. Results from this study demonstrate that the internal flux of nutrients from sediments may be a significant portion of the total load and should be accounted for in the total nutrient budget of the river for successful restoration.
Modeling the Effects of Tillage Management Practices on Herbicide Runoff in Northern Italy
Authors: Miao Zewei , Vicari Alberto , Capri Ettore , Ventura Francesca , Padovani Laura , Trevisan Marco 
Published: June 2010

ABSTRACTThe need to quantitatively predict pesticide runoff and erosion under cropping system management has gained increasing importance. In Europe, predictive models have not yet been fully validated because of the lack of field data sets. The objective of this study was to validate the capability of PRZM (Pesticide Root Zone Model) 3.12 to predict water runoff, sediment erosion, and associated transport of atrazine (6‐chloro‐N2–ethyl‐N4–isopropyl‐1,3,5‐triazine‐2,4‐diamine), terbuthylazine (N2–tert‐butyl‐6‐chloro‐N4–ethyl‐1,3,5‐triazine‐2,4‐diamine), and metolachlor [2‐chloro‐6′‐ethyl‐N‐(2‐methoxy‐l‐methylethyl)acet‐o‐toluidide] under common tillage management practices found in northern Italy. A 2‐yr field data set was used to evaluate the model. Results showed that the model could qualitatively simulate significant differences of water runoff, soil erosion, and associated herbicide losses between conventional tillage (CT) and minimum tillage (MT) for a winter barley (Hordeum vulgare L.) cover crop. For MT, water runoff, soil erosion, herbicide losses in water runoff and eroded sediment, and the proportion of herbicide loss via sediment erosion were significantly lower than for CT. The model failed to correctly simulate event‐based herbicide concentration, water runoff, and soil erosion. The model usually underestimated pesticide runoff events with high rainfall intensity and low daily precipitation volume, and overestimated runoff events with low intensity and high volume. The main reason was that the description of runoff and erosion processes is rather empirical in the model and not physically based. Moreover, model calculations do not adequately reflect the relationships between soil erosion intensity and chemical concentration in sediment losses, leading to discrepancies between predictions and field observations.
Interactions of Chlorpyrifos with Colloidal Materials in Aqueous Systems
Authors: Wu Jigang , Laird David A. 
Published: June 2010

ABSTRACTAn understanding of sorptive processes is key to describing the fate of chlorpyrifos [O,O‐diethyl‐O‐(3, 5, 6‐trichloro‐2‐pyridyl) phosphorothioate] in aquatic environments. The objectives of this study were to evaluate isotherms for adsorption and desorption of chlorpyrifos on colloidal materials and to advance understanding of interaction mechanisms between chlorpyrifos and colloidal materials. Six Ca‐saturated reference smectites, one Ca‐saturated humic acid (Ca‐humate), and one suspended sediment sample, collected from the Upper Cedar River, Iowa, were studied. A batch equilibration technique was employed to quantify adsorption and desorption isotherms for chlorpyrifos over the 0 to 100 μg L−1 concentration range in a 0.01 M CaCl2 background. Large differences in sorption affinity and variation in desorption hysteresis were found among the smectites. Neither chlorpyrifos adsorption nor its desorption were correlated with cation exchange capacity, surface area, or surface charge density of the smectites. The evidence suggests that physical interaction between chlorpyrifos and smectites is the dominant mechanism for adsorption of chlorpyrifos in aqueous systems. Chlorpyrifos was very strongly sorbed on Ca‐humate and was not desorbed from the Ca‐humate back into the aqueous solution. Chlorpyrifos was moderately sorbed on river sediment, and a large adsorption–desorption hysteresis was also found. The study implies that the nature of both organic and inorganic materials in suspended sediment can influence the adsorption–desorption behavior of chlorpyrifos in aqueous systems.
Clonal Differences in Mercury Tolerance, Accumulation, and Distribution in Willow
Authors: Wang Yaodong , Greger Maria 
Published: June 2010

ABSTRACTThis study was performed to investigate mercury (Hg) tolerance, accumulation, and translocation within the genus Salix for the potential use of this plant to remediate Hg‐contaminated sites. Six clones of willow (Salix spp.) were tested on tolerance to Hg by treating plants grown in solution culture with 0 to 15 μM HgCl2 Results showed that willow had a large variation in its sensitivity to Hg. However, the accumulation and translocation of Hg to shoots was similar in the eight tested willow clones as shown by cold vapor atomic absorption spectrometry analysis when plants were treated with 0.5 μM HgCl2 in a nutrient solution. The majority of total Hg accumulated was localized to the roots, whereas only 0.45 to 0.62% of the total Hg accumulated via roots was translocated to the shoots. Thus, the root system is the main tissue of willow that accumulates Hg and the majority of the Hg in the root system (80%) was bound in the cell wall.
Leaching and Crop Uptake of Nitrogen from Nitrogen‐15‐Labeled Green Manures and Ammonium Nitrate
Authors: Bergström Lars , Kirchmann Holger 
Published: June 2010

ABSTRACTGreen manures can be used as an N source for agricultural crops as a substitute for inorganic N fertilizers. The effects of using green manures on leaching and uptake of N by spring barley (Hordeum vulgareL.) were evaluated in a 2‐yr lysimeter study. Ryegrass (Lolium perenneL.) and red clover (Trifolium pratenseL.) labeled with15N were applied in May of the first year at 160 kg total N ha−1Simultaneously,15NH415NO3was applied at 80 kg N ha−1to additional lysimeters and others were left without N additions (control). During the second year, all lysimeters, except the control, received 80 kg N ha−1as unlabeled NH4NO3The cumulative, average loads of total N leached during the two years were: 37 (control), 62 (NH4NO3), 50 (ryegrass manure), and 73 (red clover manure) kg ha−1The differences among the treatments were not significant (P> 0.05), but the control had significantly smaller (P< 0.05) leaching loads than the treatments. About 24% of ryegrass‐ and red clover–derived N and 43% of NH4NO3were removed through spring barley grain and stover during the two growing seasons. Thus, the N use efficiency in barley was substantially larger when grown with inorganic N fertilizer than when grown with green manure. Viewed in combination with the tendency for larger N leaching loads under red clover manure, claims about water quality benefits of legume‐based green manures should be evaluated with regard to the timing of N release and demand for N by the plant.
Relevance of Organic Matter Fractions as Predictors of Wastewater Sludge Mineralization in Soil
Authors: Parnaudeau Virginie , Nicolardot Bernard , Pagès Jérôme 
Published: June 2010

ABSTRACTSeventeen different wastewater sludges were characterized using both chemical and organic matter fractionation methods (water extraction, Van Soest method, and acid hydrolysis) and 6‐mo incubation studies to assess their decomposition in soil. Simple correlation and multiple factor analysis (MFA) were then performed to establish relationships between composition and C and N mineralization of sludges. Carbon and N concentrations covered a wide range of values, but organic carbon (Co) to organic nitrogen (No) ratios were relatively low (from 5 to 19). Carbon and N were mainly distributed in the most soluble fractions of the Van Soest method and in the water‐insoluble fraction at 100°C. Carbon mineralization varied from 180 to 661 g C kg−1organic C added during the 168‐d incubation. The addition of sludges led to different inorganic N dynamics: from −3.3 to +120.0 g N kg−1sludge organic C mineralized after the 168‐d incubation. Fractionation studies showed that the most discriminating method was acid hydrolysis. Carbon mineralization was linked with the proportion of sludge N and C present in the lignin‐like fraction (r= −0.68 and −0.65, respectively). Significant relationships were established between N mineralization and Noto Coratio (0.88 <r< 0.95) and the Coto Noratio of sludges, the C to N ratio of the soluble fraction obtained by the Van Soest method, the water‐soluble fraction at 100°C, and the C and N present in the acid‐hydrolyzable fraction. Finally, multiple factor analysis also enabled establishing a sludge typology using five clusters based on composition and mineralization characteristics.
The Effect of pH on Metal Accumulation in Two Alyssum Species
Authors: Kukier Urszula , Peters Carinne A. , Chaney Rufus L. , Angle J. Scott , Roseberg Richard J. 
Published: June 2010

ABSTRACTNickel phytoextraction using hyperaccumulator plants offers a potential for profit while decontaminating soils. Although soil pH is considered a key factor in metal uptake by crops, little is known about soil pH effects on metal uptake by hyperaccumulator plants. Two Ni and Co hyperaccumulators, Alyssum murale and A. corsicum, were grown in Quarry muck (Terric Haplohemist) and Welland (Typic Epiaquoll) soils contaminated by a Ni refinery in Port Colborne, Ontario, Canada, and in the serpentine Brockman soil (Typic Xerochrepts) from Oregon, USA. Soils were acidified and limed to cover pH from strongly acidic to mildly alkaline. Alyssum grown in both industrially contaminated soils exhibited increased Ni concentration in shoots as soil pH increased despite a decrease in water‐soluble soil Ni, opposite to that seen with agricultural crop plants. A small decrease in Alyssum shoot Ni concentration as soil pH increased was observed in the serpentine soil. The highest fraction of total soil Ni was phytoextracted from Quarry muck (6.3%), followed by Welland (4.7%), and Brockman (0.84%). Maximum Ni phytoextraction was achieved at pH 7.3, 7.7, and 6.4 in the Quarry, Welland, and Brockman soils, respectively. Cobalt concentrations in shoots increased with soil pH increase in the Quarry muck, but decreased in the Welland soil. Plants extracted 1.71, 0.83, and 0.05% of the total soil Co from Welland, Quarry, and Brockman, respectively. The differences in uptake pattern of Ni and Co by Alyssum from different soils and pH were probably related to the differences in organic matter and iron contents of the soils.
Using Nitrogen‐15 to Quantify Vegetative Buffer Effectiveness for Sequestering Nitrogen in Runoff
Authors: Bedard‐Haughn A. , Tate K. W. , van Kessel C. 
Published: June 2010

ABSTRACTPrevious studies have observed higher levels of soluble nutrients leaving vegetative buffers than entering them, suggesting that the buffers themselves are acting as a source rather than a sink by releasing previously stored nutrients. This study used 98 atom % 15N‐labeled KNO3 at a rate of 5 kg ha−1 to quantify buffer efficiency for sequestering new inputs of NO−3–N in an extensively grazed irrigated pasture system. Buffer treatments consisted of an 8‐m buffer, a 16‐m buffer, and a nonbuffered control. Regardless of the form of runoff N (NO−3, NH+4, or dissolved organic nitrogen [DON]), more 15N was lost from the nonbuffered treatments than from the buffered treatments. The majority of the N attenuation was by vegetative uptake. Over the course of the study, the 8‐m buffer decreased NO−3–15N load by 28% and the 16‐m buffer decreased load by 42%. For NH+4–15N, the decrease was 34 and 48%, and for DON–15N, the decrease was 21 and 9%. Although the buffers were effective overall, the majority of the buffer impact occurred in the first four weeks after 15N application, with the buffered plots attenuating nearly twice as much 15N as the nonbuffered plots. For the remainder of the study, buffer effect was not as marked; there was a steady release of 15N, particularly NO−3– and DON–15N, from the buffers into the runoff. This suggests that for buffers to be sustainable for N sequestration there is a need to manage buffer vegetation to maximize N demand and retention.
Effect of Root Death and Decay on Dissipation of Polycyclic Aromatic Hydrocarbons in the Rhizosphere of Yellow Sweet Clover and Tall Fescue
Authors: Parrish Zakia D. , Banks M. Katherine , Schwab A. Paul 
Published: June 2010

ABSTRACTA 12‐mo greenhouse study was conducted to evaluate the contribution of root death and decay on the dissipation of polycyclic aromatic hydrocarbons (PAHs) in rhizosphere soil. The contaminated soil was previously treated by land‐farming, but residual PAHs remained after treatment. Tall fescue (Festuca arundinacea Schreb.) and yellow sweet clover (Melilotus officinalis Lam.) were the target plants. To specifically evaluate the effect of root decay on contaminant dissipation, plants were treated with glyphosate, a broad spectrum herbicide, to induce root decay. Although tall fescue treatments had the highest root and shoot biomass and root surface area, this plant did not result in the highest contaminant degradation rates. Significant differences were noted between treatments for seven PAHs, with the active yellow sweet clover resulting in 60 to 75% degradation of these compounds. Induced root death and decay did not produce a significant enhancement of PAH degradation. The PAH microbial degrader populations in the vegetated treatments were more than 100 times greater than those in the unvegetated control. The phospholipid fatty acid (PLFA) structural group profile shifted over the growing period, indicating a change in the community structure. In conclusion, phytoremediation was shown to be an effective polishing tool for PAH‐affected soil previously subjected to biological treatment.
Characterizing Land Surface Erosion from Cesium‐137 Profiles in Lake and Reservoir Sediments
Authors: Zhang Xinbao , Walling Desmond E. 
Published: June 2010

ABSTRACTRecognition of the threat to the sustainable use of the earth's resources posed by soil erosion and associated off‐site sedimentation has generated an increasing need for reliable information on global rates of soil loss. Existing methods of assessing rates of soil loss across large areas possess many limitations and there is a need to explore alternative approaches to characterizing land surface erosion at the regional and global scale. The downcore profiles of 137Cs activity available for numerous lakes and reservoirs located in different areas of the world can be used to provide information on land surface erosion within the upstream catchments. The rate of decline of 137Cs activity toward the surface of the sediment deposited in a lake or reservoir can be used to estimate the rate of surface lowering associated with eroding areas within the upstream catchment, and the concentration of 137Cs in recently deposited sediment provides a basis for estimating the relative importance of surface and channel, gully, and/or subsurface erosion as a source of the deposited sediment. The approach has been tested using 137Cs data from several lakes and reservoirs in southern England and China, spanning a wide range of specific suspended sediment yield. The results obtained are consistent with other independent evidence of erosion rates and sediment sources within the lake and reservoir catchments and confirm the validity of the overall approach. The approach appears to offer valuable potential for characterizing land surface erosion, particularly in terms of its ability to provide information on the rate of surface lowering associated with the eroding areas, rather than an average rate of lowering for the entire catchment surface.
Cascading Ecological Effects of Low‐Level Phosphorus Enrichment in the Florida Everglades
Authors: Gaiser Evelyn E. , Trexler Joel C. , Richards Jennifer H. , Childers Daniel L. , Lee David , Edwards Adrienne L. , Scinto Leonard J. , Jayachandran Krish , Noe Gregory B. , Jones Ronald D. 
Published: June 2010

ABSTRACTFew studies have examined long‐term ecological effects of sustained low‐level nutrient enhancement on wetland biota. To determine sustained effects of phosphorus (P) addition on Everglades marshes we added P at low levels (5, 15, and 30 μg L−1 above ambient) for 5 yr to triplicate 100‐m flow‐through channels in pristine marsh. A cascade of ecological responses occurred in similar sequence among treatments. Although the rate of change increased with dosing level, treatments converged to similar enriched endpoints, characterized most notably by a doubling of plant biomass and elimination of native, calcareous periphyton mats. The full sequence of biological changes occurred without an increase in water total P concentration, which remained near ambient levels until Year 5. This study indicates that Everglades marshes have a near‐zero assimilative capacity for P without a state change, that ecosystem responses to enrichment accumulate over time, and that downstream P transport mainly occurs through biota rather than the water column.
Role of interferon gamma release assay in the diagnosis of Pott disease
Authors: Kumar Raj , Das Rupant K. , Mahapatra Ashok Kumar 
Published: June 2010

Object
Tuberculosis is ubiquitous in its presence and in its myriad manifestations. Despite several advances, it often poses a diagnostic dilemma. The aim of this study was to evaluate the efficacy of the QuantiFERON assay in the diagnosis of Pott disease.

Methods
In this study, 70 consecutive patients with vertebral collapse underwent a battery of investigations including radiological evaluation (MR imaging and chest and spine radiography), routine blood workup (hemoglobin, total leukocyte count, differential leukocyte count, and erythrocyte sedimentation rate), enzyme-linked immunosorbent assay (ELISA) for tuberculosis, a bone scan and the QuantiFERON assay, perioperative evaluation, and bacteriological studies. The patients were then classified as having tuberculosis on the basis of positive smear or culture, a biopsy consistent with tuberculosis, or a therapeutic response to antituberculosis chemotherapy on follow-up. The efficacy of the investigations, both individually and in combination, were evaluated.

Results
Tuberculosis was diagnosed in 51 patients, and 19 had vertebral collapse that was attributable to other causes. Based on the authors' data, sensitivity of the QuantiFERON assay in the diagnosis of tuberculosis of the spine was 84% and specificity was 95%. In combination with radiological criteria, bone scan, and ELISA, the QuantiFERON assay was predictive of tuberculosis in 90% of cases (46 patients).

Conclusions
None of the investigative modalities individually are efficacious enough to make a diagnosis of tuberculosis of the spine with such a degree of certainty as to to obviate the need for a tissue diagnosis or bacteriological confirmation. The ELISA, MR imaging of the spine, and bone scanning findings provide a reasonably certain diagnosis in 90% of cases, providing the grounds for starting a safe trial of antituberculous chemotherapy.
Comparison of patient and surgeon ratings of outcome 12 months after spine surgery
Authors: Porchet François , Lattig Friederike , Grob Dieter , Kleinstueck Frank S. , Jeszenszky Dezsö , Paus Christophe , O'Riordan David , Mannion Anne F. 
Published: June 2010

ObjectThe contemporary assessment of spine surgical outcome primarily relies on patient-centered reports of symptoms and function. Such measures are considered to reduce bias compared with traditional surgeon-based outcome ratings. This study examined the agreement between patients' and surgeons' ratings of outcome 1 year after spine surgery.MethodsThe study involved 404 patients (mean age 56.6 ± 16.4 years; 259 women, 145 men) and their treating surgeons. At baseline and 12 months postoperatively patients completed the Core Outcome Measures Index (COMI) rating pain, function, quality of life, and disability. At 12 months postoperatively, they also rated the global outcome of surgery and their satisfaction with treatment. The surgeon, blinded to the patient's evaluation, rated the global outcome of surgery as excellent, good, fair, or poor.ResultsSeventy-six percent of the patients who were considered by the surgeon to have an excellent or good outcome achieved the minimum clinically important difference (MCID) of a 2.2-point reduction on the COMI; 24% achieved less than the MCID. There was a significant correlation between the surgeons' and patients' global outcome ratings (Spearman ρ = 0.56; p < 0.0001). The degree of absolute agreement between them was significantly influenced by surgeon seniority: senior surgeons “overrated” the outcome in 24.5% of cases (compared with patients' ratings) and “underrated” it in 17.5% of cases. Junior surgeons overrated in 7.8% of cases and underrated in 43.8% of cases (p < 0.0001). Surgeon overrating occurred significantly more frequently for patients with a poor self-rated outcome (measured as global outcome, COMI score, or satisfaction with treatment). In a multivariate model, the independent variables “senior surgeon” and “patient dissatisfaction with care” were the most significant unique predictors of surgeon overrating of the global outcome (p < 0.0001; adjusted R2for the model = 0.16).ConclusionsOverall, agreement between surgeon and patient was reasonably good. The majority of patients who were rated as excellent/good by the surgeons had achieved the MCID in the prospectively measured COMI score. Discrepancies in outcome ratings were influenced by surgeon seniority and patient satisfaction. For a balanced view of the surgical result, outcomes should be assessed from the perspectives of both the patient and the surgeon.