bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitrate Retention in Riparian Ground Water at Natural and Elevated Nitrate Levels in North Central Minnesota
Authors: Duff John H. , Jackman Alan P. , Triska Frank J. , Sheibley Richard W. , Avanzino Ronald J. 
Published: January 2007

ABSTRACTThe relationship between local ground water flows and NO3− transport to the channel was examined in three well transects from a natural, wooded riparian zone adjacent to the Shingobee River, MN. The hillslope ground water originated as recharge from intermittently grazed pasture up slope of the site. In the hillslope transect perpendicular to the stream, ground water NO3− concentrations decreased from ∼3 mg N L−1 beneath the ridge (80 m from the channel) to 0.01 to 1.0 mg N L−1 at wells 1 to 3 m from the channel. The Cl− concentrations and NO3/Cl ratios decreased toward the channel indicating NO3− dilution and biotic retention. In the bankside well transect parallel to the stream, two distinct ground water environments were observed: an alluvial environment upstream of a relict beaver dam influenced by stream water and a hillslope environment downstream of the relict beaver dam. Nitrate was elevated to levels representative of agricultural runoff in a third well transect located ∼5 m from the stream to assess the effectiveness of the riparian zone as a NO3− sink. Subsurface NO3− injections revealed transport of up to 15 mg N L−1 was nearly conservative in the alluvial riparian environment. Addition of glucose stimulated dissolved oxygen uptake and promoted NO3− retention under both background and elevated NO3− levels in summer and winter. Disappearance of added NO3− was followed by transient NO2− formation and, in the presence of C2H2, by N2O formation, demonstrating potential denitrification. Under current land use, most NO3− associated with local ground water is biotically retained or diluted before reaching the channel. However, elevating NO3− levels through agricultural cultivation would likely result in increased NO3− transport to the channel.
Quantifying Constraints Imposed by Calcium and Iron on Bacterial Reduction of Uranium(VI)
Authors: Stewart Brandy D. , Neiss Jim , Fendorf Scott 
Published: January 2007

ABSTRACTUranium is a redox active contaminant of concern to both human health and ecological preservation. In anaerobic soils and sediments, the more mobile, oxidized form of uranium (UO22+ and associated species) may be reduced by dissimilatory metal‐reducing bacteria. Despite rapid reduction in controlled, experimental systems, various factors within soils or sediments may limit biological reduction of U(VI), inclusive of competing electron acceptors and alterations in uranyl speciation. Here we elucidate the impact of U(VI) speciation on the extent and rate of reduction, and we examine the impact of Fe(III) (hydr)oxides (ferrihydrite, goethite, and hematite) varying in free energies of formation. Observed pseudo first‐order rate coefficients for U(VI) reduction vary from 12 ± 0.60 × 10−3 h−1 (0 mM Ca in the presence of goethite) to 2.0 ± 0.10 × 10−3 h−1 (0.8 mM Ca in the presence of hematite). Nevertheless, dissolved Ca (at concentrations from 0.2 to 0.8 mM) decreases the extent of U(VI) reduction by ∼25% after 528 h relative to rates without Ca present. Imparting an important criterion on uranium reduction, goethite and hematite decrease the dissolved concentration of calcium through adsorption and thus tend to diminish the effect of calcium on uranium reduction. Ferrihydrite, in contrast, acts as a competitive electron acceptor and thus, like Ca, decreases uranium reduction. However, while ferrihydrite decreases U(VI) in solutions without Ca, with increasing Ca concentrations U(VI) reduction is enhanced in the presence of ferrihydrite (relative to its absence)—U(VI) reduction, in fact, becomes almost independent of Ca concentration. The quantitative framework described herein helps to predict the fate and transport of uranium within anaerobic environments.
Phosphorus Transport Pathways to Streams in Tile‐Drained Agricultural Watersheds
Authors: Gentry L. E. , David M. B. , Royer T. V. , Mitchell C. A. , Starks K. M. 
Published: January 2007

ABSTRACTAgriculture is a major nonpoint source of phosphorus (P) in the Midwest, but how surface runoff and tile drainage interact to affect temporal concentrations and fluxes of both dissolved and particulate P remains unclear. Our objective was to determine the dominant form of P in streams (dissolved or particulate) and identify the mode of transport of this P from fields to streams in tile‐drained agricultural watersheds. We measured dissolved reactive P (DRP) and total P (TP) concentrations and loads in stream and tile water in the upper reaches of three watersheds in east‐central Illinois (Embarras River, Lake Fork of the Kaskaskia River, and Big Ditch of the Sangamon River). For all 16 water year by watershed combinations examined, annual flow‐weighted mean TP concentrations were >0.1 mg L−1, and seven water year by watershed combinations exceeded 0.2 mg L−1 Concentrations of DRP and particulate P (PP) increased with stream discharge; however, particulate P was the dominant form during overland runoff events, which greatly affected annual TP loads. Concentrations of DRP and PP in tiles increased with discharge, indicating tiles were a source of P to streams. Across watersheds, the greatest DRP concentrations (as high as 1.25 mg L−1) were associated with a precipitation event that followed widespread application of P fertilizer on frozen soils. Although eliminating this practice would reduce the potential for overland runoff of P, soil erosion and tile drainage would continue to be important transport pathways of P to streams in east‐central Illinois.
Seasonality of Selected Surface Water Constituents in the Indian River Lagoon, Florida
Authors: Qian Y. , Migliaccio K. W. , Wan Y. , Li Y. C. , Chin D. 
Published: January 2007

ABSTRACTSeasonality is often the major exogenous effect that must be compensated for or removed to discern trends in water quality. Our objective was to provide a methodological example of trend analysis using water quality data with seasonality. Selected water quality constituents from 1979 to 2004 at three monitoring stations in southern Florida were evaluated for seasonality. The seasonal patterns of flow‐weighted and log‐transformed concentrations were identified by applying side‐by‐side boxplots and the Wilcoxon signed‐rank test (p < 0.05). Seasonal and annual trends were determined by trend analysis (Seasonal Kendall or Tobit procedure) using the U.S. Geological Survey (USGS) Estimate TREND (ESTREND) program. Major water quality indicators (specific conductivity, turbidity, color, and chloride), except for turbidity at Station C24S49, exhibited significant seasonal patterns. Almost all nutrient species (NO2–N, NH4–N, total Kjeldahl N, PO4–P, and total P) had an identical seasonal pattern of concentrations significantly greater in the wet than in the dry season. Some water quality constituents were observed to exhibit significant annual or seasonal trends. In some cases, the overall annual trend was insignificant while opposing trends were present in different seasons. By evaluating seasonal trends separately from all data, constituents can be assessed providing a more accurate interpretation of water quality trends.
Nitrogen and Phosphorus Budgets in Experimental Grasslands of Variable Diversity
Authors: Oelmann Yvonne , Kreutziger Yvonne , Temperton Vicky M. , Buchmann Nina , Roscher Christiane , Schumacher Jens , Schulze Ernst‐Detlef , Weisser Wolfgang W. , Wilcke Wolfgang 
Published: January 2007

ABSTRACTPrevious research has shown that plant diversity influences N and P cycles. However, the effect of plant diversity on complete ecosystem N and P budgets has not yet been assessed. For 20 plots of artificially established grassland mixtures differing in plant diversity, we determined N and P inputs by bulk and dry deposition and N and P losses by mowing (and subsequent removal of the biomass) and leaching from April 2003 to March 2004. Total deposition of N and P was 2.3 ± 0.1 and 0.2 ± 0.01 g m−2 yr−1, respectively. Mowing was the main N and P loss. The net N and P budgets were negative (–6.3 ± 1.1 g N and –1.9 ± 0.2 g P m−2 yr−1). For N, this included a conservative estimate of atmospheric N2 fixation. Nitrogen losses as N2O were expected to be small at our study site (<0.05 g m−2 yr−1). Legumes increased the removal of N with the harvest and decreased leaching of NH4–N and dissolved organic nitrogen (DON) from the canopy. Reduced roughness of grass‐containing mixtures decreased dry deposition of N and P. Total dissolved P and NO3–N leaching from the canopy increased in the presence of grasses attributable to the decreased N and P demand of grass‐containing mixtures. Species richness did not have an effect on any of the studied fluxes. Our results demonstrate that the N and P fluxes in managed grassland are modified by the presence or absence of particular functional plant groups and are mainly driven by the management.
Factors Influencing the Concentration of Volatile Fatty Acids, Ammonia, and Other Nutrients in Stored Liquid Pig Manure
Authors: Conn Kenneth L. , Topp Edward , Lazarovits George 
Published: January 2007

ABSTRACTIn order to minimize odor and manage nutrients in liquid pig manure we need to be able to predict what operational practices most influence the concentrations of volatile fatty acids (VFAs), ammonium nitrogen (NH4+–N), and other nutrients present in the manure. To determine this, we collected manure from 15 pig operations in southwestern Ontario in the fall of 2001 and 2002 and spring of 2002 and 2003. The manure was stored in concrete tanks at all operations. Manure from finishing pigs had the highest concentration of VFAs, NH4+–N, and other nutrients, followed by manure from mixed operations, and then manure from sow operations. The average concentration of total VFAs and NH4+–N in finishing pig manure was 166 mM compared with 36 and 99 mM, respectively, in sow manure. Total N, P, and K were 2.3, 2.5, and 1.7 times greater, respectively, in finishing pig compared with sow manure. There was no seasonal or year to year variation in amount. The diet of the pigs, use of feed additives or antibiotics, location of tanks, and whether the tanks were covered or mixed were not significant factors contributing to the difference in manure chemistry. The main reason for the differences between the three types of manure was manure dilution. The average dry matter content of finishing pig manure was 4.5 times that of sow manure. This was due to larger density of pigs in finishing compared with sow operations, less manure storage capacity per pig for finishing compared with sow operations, and more wash water being used for sow operations.
Prairie and Turf Buffer Strips for Controlling Runoff from Paved Surfaces
Authors: Steinke K. , Stier J. C. , Kussow W. R. , Thompson A. 
Published: January 2007

ABSTRACTEutrophication of surface waters due to nonpoint source pollution from urban environments has raised awareness of the need to decrease runoff from roads and other impervious surfaces. These concerns have led to precautionary P application restrictions on turf and requirements for vegetative buffer strips. The impacts of two plant communities and three impervious/pervious surface ratios were assessed on runoff water quality and quantity. A mixed forb/grass prairie and a Kentucky bluegrass (Poa pratensis L.) blend were seeded and runoff was monitored and analyzed for total volume, total P, soluble P, soluble organic P, bioavailable P, total suspended solids, and total organic suspended solids. Mean annual runoff volumes, all types of mean annual P nutrient losses, and sediment loads were not significantly affected by treatments because over 80% of runoff occurred during frozen soil conditions. Total P losses from prairie and turf were similar, averaging 1.96 and 2.12 kg ha−1 yr−1, respectively. Vegetation appeared to be a likely contributor of nutrients, particularly from prairie during winter dormancy. When runoff occurred during non‐frozen soil conditions turf allowed significantly (P ≤ 0.10) lower runoff volumes compared with prairie vegetation and the 1:2 and 1:4 impervious/pervious surface ratios had less runoff than the 1:1 ratio (P ≤ 0.05). In climates where the majority of runoff occurs during frozen ground conditions, vegetative buffers strips alone are unlikely to dramatically reduce runoff and nutrient loading into surface waters. Regardless of vegetation type or size, natural nutrient biogeochemical cycling will cause nutrient loss in surface runoff waters, and these values may represent baseline thresholds below which values cannot be obtained.
Application Methods Affect Phosphorus‐Induced Lead Immobilization from a Contaminated Soil
Authors: Yoon Joon Ki , Cao Xinde , Ma Lena Q. 
Published: January 2007

ABSTRACTPhosphate rock (PR) and phosphoric acid (PA) are an effective combination of P sources for immobilizing Pb in contaminated soils. This column experiment examined the effectiveness of different application methods on Pb immobilization in a contaminated soil. Phosphate was applied at a P/Pb molar ratio of 4 with half as PR and half PA. While PR was mixed with the soil or placed as a layer, aqueous PA was applied from the top of the column as one or two applications. After 4 wk of incubation, total and soluble Pb and P, TCLP‐Pb (toxicity characteristic leaching procedure) and PBET‐Pb (physiologically‐based extraction test) in the P‐treated soil were determined. Phosphate addition effectively reduced leachable Pb to below the EPA drinking water standard of 15 μg L−1 in all treatments. Mixing both PA and PR with the soil was the most effective method in Pb immobilization, reducing TCLP‐Pb by up to 95% and PBET‐Pb by 25 to 42%. Application of PR as a layer in the soil column was the most effective in reducing Pb migration (by 73–79%) and minimizing soil acidification and P entrophication, potential drawbacks of PA. Applying PA in two applications was less effective than one application. Mixing PR and PA with the soil plus placing PR as a layer can be employed for effective remediation of Pb‐contaminated soils, reducing Pb leachability, bioavailability, and mobility while minimizing soil acidification and P entrophication.
What Aspect of Dietary Modification in Broilers Controls Litter Water‐Soluble Phosphorus
Authors: Leytem A. B. , Plumstead P. W. , Maguire R. O. , Kwanyuen P. , Brake J. 
Published: January 2007

ABSTRACTEnvironmental concerns about phosphorus (P) losses from animal agriculture have led to interest in dietary strategies to reduce the concentration and solubility of P in manures and litters. To address the effects of dietary available phosphorus (AvP), calcium (Ca), and phytase on P excretion in broilers, 18 dietary treatments were applied in a randomized complete block design to each of four replicate pens of 28 broilers from 18 to 42 d of age. Treatments consisted of three levels of AvP (3.5, 3.0, and 2.5 g kg−1) combined with three levels of Ca (8.0, 6.9, and 5.7 g kg−1) and two levels of phytase (0 and 600 phytase units [FTU]). Phytase was added at the expense of 1.0 g kg−1 P from dicalcium phosphate. Fresh litter was collected from pens when the broilers were 41 d of age and analyzed for total P, soluble P, and phytate P as well as P composition by 31P nuclear magnetic resonance (NMR) spectroscopy. Results indicated that the inclusion of phytase at the expense of inorganic P or reductions in AvP decreased litter total P by 28 to 43%. Litter water‐soluble P (WSP) decreased by up to 73% with an increasing dietary Ca/AvP ratio, irrespective of phytase addition. The ratio of WSP/total P in litter decreased as the dietary Ca/AvP ratio increased and was greater in the phytase‐amended diets. This study indicated that while feeding reduced AvP diets with phytase decreased litter total P, the ratio of Ca/AvP in the diet was primarily responsible for effects on WSP. This is important from an environmental perspective as the amount of WSP in litter could be related to potential for off‐site P losses following land application of litter.
Increasing Expenditure on Health Care Incurred by Diabetic Subjects in a Developing Country
Authors: Ramachandran Ambady , Ramachandran Shobhana , Snehalatha Chamukuttan , Augustine Christina , Murugesan Narayanasamy , Viswanathan Vijay , Kapur Anil , Williams Rhys 
Published: January 2007

OBJECTIVE— This study aimed to assess the direct cost incurred by diabetic subjects who were in different income groups in urban and rural India, as well as to examine the changing trends of costs in the urban setting from 1998 to 2005.
RESEARCH DESIGN AND METHODS— A total of 556 diabetic subjects from various urban and rural regions of seven Indian states were enrolled. A brief uniform coded questionnaire (24 items) on direct cost was used.
RESULTS— Annual family income was higher in urban subjects (rupees [Rs] 100,000 or $2,273) than in the rural subjects (Rs 36,000 or $818) (P &lt; 0.001). Total median expenditure on health care was Rs 10,000 ($227) in urban and Rs 6,260 ($142) in rural (P &lt; 0.001) subjects. Treatment costs increased with duration of diabetes, presence of complications, hospitalization, surgery, insulin therapy, and urban setting. Lower-income groups spent a higher proportion of their income on diabetes care (urban poor 34% and rural poor 27%). After accounting for inflation, a secular increase of 113% was observed in the total expenses between 1998 and 2005 in the urban population. The highest increase in percentage of household income devoted to diabetes care was in the lowest economic group (34% of income in 1998 vs. 24.5% in 2005) (P &lt; 0.01). There was a significant improvement in urban subjects in medical reimbursement from 2% (1998) to 21.3% (2005).
CONCLUSIONS— Urban and rural diabetic subjects spend a large percentage of income on diabetes management. The economic burden on urban families in developing countries is rising, and the total direct cost has doubled from 1998 to 2005.
Insulin Resistance as Estimated by Homeostasis Model Assessment Predicts Incident Symptomatic Cardiovascular Disease in Caucasian Subjects From the General Population
Authors: Bonora Enzo , Kiechl Stefan , Willeit Johann , Oberhollenzer Friedrich , Egger Georg , Meigs James B. , Bonadonna Riccardo C. , Muggeo Michele 
Published: January 2007

OBJECTIVE—The purpose of this study was to evaluate whether insulin resistance is associated to cardiovascular disease (CVD) and to understand whether this association can be explained by traditional and novel CVD risk factors associated with this metabolic disorder.
RESEARCH DESIGN AND METHODS—We examined a sample representative of the population of Bruneck, Italy (n = 919; aged 40–79 years). Insulin-resistant subjects were those with a score in the top quartile of the homeostasis model assessment (HOMA) for insulin resistance (HOMA-IR). Risk factors correlated with insulin resistance included BMI, A1C, HDL cholesterol, triglycerides, blood pressure, high-sensitivity C-reactive protein (hsCRP), fibrinogen, oxidized LDL, vascular cell adhesion molecule-1 (VCAM-1), and adiponectin. Subjects without CVD at baseline were followed up for 15 years for incident CVD, a composite end point including fatal and nonfatal myocardial infarction and stroke, transient ischemic attack, and any revascularization procedure.
RESULTS—During follow-up, 118 subjects experienced a first symptomatic CVD event. Levels of HOMA-IR were higher at baseline among subjects who developed CVD (2.8) compared with those remaining free of CVD (2.5) (P &lt; 0.05). Levels of HOMA-IR also were significantly correlated (P &lt; 0.05) with most CVD risk factors we evaluated. In Cox proportional hazard models, insulin-resistant subjects had an age-, sex-, and smoking-adjusted 2.1-fold increased risk (95% CI 1.3–3.1) of incident symptomatic CVD relative to non–insulin-resistant subjects. After sequential adjustment for physical activity and classic risk factors (A1C, LDL cholesterol, and hypertension) as well as BMI, HDL cholesterol, triglycerides, and novel risk factors, including fibrinogen, oxidized LDL, hsCRP, VCAM-1, and adiponectin, the association between HOMA-IR and incident CVD remained significant and virtually unchanged (hazard ratio 2.2 [95% CI 1.4–3.6], P &lt; 0.001).
CONCLUSIONS—HOMA-estimated insulin resistance is associated with subsequent symptomatic CVD in the general population independently of all classic and several nontraditional risk factors. These data suggest that insulin resistance may be an important target to reduce CVD risk.
Effect of Adjunctive Pramlintide Treatment on Treatment Satisfaction in Patients With Type 1 Diabetes
Authors: Marrero David G. , Crean John , Zhang Bei , Kellmeyer Terrie , Gloster Maurice , Herrmann Kathrin , Rubin Richard , Fineberg Naomi , Kolterman Orville 
Published: January 2007

OBJECTIVE—To assess the effect of adjunctive pramlintide treatment on treatment satisfaction in patients with type 1 diabetes treated with intensive insulin regimens.
RESEARCH DESIGN AND METHODS—Intensively treated (multiple daily injection [MDI] or continuous subcutaneous insulin infusion [CSII] pump therapy) patients with type 1 diabetes completed a study-specific treatment satisfaction questionnaire following 29 weeks of either placebo (n = 136) or pramlintide (n = 130) treatment in a double-blind, noninferiority pramlintide dose titration trial. End points included patient reported outcomes, their relationship to insulin treatment regimen, A1C, weight, and insulin use.
RESULTS—Pramlintide-treated patients reported greater treatment satisfaction in most questionnaire responses. Treatment satisfaction was similar for pramlintide-treated patients regardless of intensive insulin regimens (MDI versus CSII). Mean A1C was reduced to a similar degree in both pramlintide- (−0.39 ± 0.07%) and placebo-treated (−0.45 ± 0.07%) patients. However, pramlintide treatment was associated with reductions in mean body weight (−1.50 ± 0.33 kg; P &lt; 0.0001) and mealtime insulin use (−19.05 ± 5.17%; P &lt; 0.005) over 29 weeks, while placebo treatment resulted in weight gain (1.28 ± 0.25 kg) and a smaller reduction in mealtime insulin use (−2.20 ± 3.33%).
CONCLUSIONS—Despite similar reductions in A1C, pramlintide treatment resulted in greater treatment satisfaction compared with placebo treatment. This was independent of insulin delivery method.