Effects of Fluoride on Agriculture

The effects of atmospheric fluorides on plants are summarized with respect to the level of biological organization at which they occur. The factors that determine the occurrence and degree of these effects are reviewed briefly. A series of economic effects on agriculture is postulated and its possible relationship to the botanical effects of fluorides is discussed.     

Precision and Accuracy in the Determination of Sulfur Oxides,Fluoride, and Spherical Aluminosilicate Fly Ash Particles in Project MOHAVE

The precision and accuracy of the determination of particu-late sulfate and fluoride, and gas phase SO₂ and HF are estimated from the results obtained from collocated replicate samples and from collocated comparison samples for high-and low-volume filter pack and annular diffusion denuder samplers. The results of replicate analysis of collocated samples and replicate analyses of a given sample for the determination of spherical aluminosilicate fly ash particles have also been compared. Each of these species is being used in the chemical mass balance source apportionment of sulfur oxides in the Grand Canyon region as part of Project MOHAVE, and the precision and accuracy analyses given in this paper provide input to that analysis. The precision of the various measurements reported here is ±1.8 nmol/m³ and ±2.5 nmol/m³ for the determination of SO₂ and sulfate, respectively, with an annular denuder. The precision is ±0.5 nmol/m³ and ±2.0 nmol/m³ for the determination of the same species with a high-volume or low-volume filter pack. The precision for the determination of the sum of HF(g) and fine particulate fluoride is ±0.3 nmol/m³. The precision for the determination of aluminosilicate fly ash particles is ±100 particles/m³. At high concentrations of the various species, reproducibility of the various measurements is ±10% to ±14% of the measured concentration. The concentrations of sulfate determined using filter pack samplers are frequently higher than those determined using diffusion denuder sampling systems. The magnitude of the difference (e.g., 2-10 nmol sulfate/m³) is small, but important relative to the precision of the data and the concentrations of particulate sul-fate present (typically 5-20 nmol sulfate/m³). The concentrations of SO₂(g) determined using a high-volume cascade impactor filter pack sampler are correspondingly lower than those obtained with diffusion denuder samplers. The concentrations of SO_x (SO₂(g) plus particulate sulfate) determined using the two samplers during Project MOHAVE at the Spirit Mountain, NV, and Hopi Point, AZ, sampling sites were in agreement. However, for samples collected at Painted Desert, AZ, and Meadview, AZ, the concentrations of SO_x and SO₂(g) determined with a high-volume cascade impactor filter pack sampler were frequently lower than those determined using a diffusion denuder sampling system. These two sites had very low ambient relative humidity, an average of 25%. Possible causes of observed differences in the SO₂(g) and sulfate results obtained from different types of samplers are given.     

A preliminary in vitro assessment of GroBiotic-A, brewer's yeast and fructooligosaccharide as prebiotics for the red drum Sciaenops ocellatus

This study examined the effects of brewers yeast, fructooligosaccharide (FOS), and GroBiotic-A, a mixture of partially autolyzed brewers yeast, dairy components and dried fermentation products, on the intestinal microbial community of red drum, Sciaenops ocellatus. Gastrointestinal (GI) tracts were aseptically removed from three sub-adult red drum previously maintained on a commercial diet and placed in an anaerobic chamber. Intestinal contents were removed, diluted and incubated in vitro in one of four liquid media: normal diet alone, diet + 2% (w/w) GroBiotic-A, diet + 2% brewers yeast, and diet + 2% FOS. After 24 and 48 h of incubation at 25 degrees C, supernatants were removed for volatile fatty acid (VFA) analysis and DNA was extracted for denaturing gradient gel electrophoresis (DGGE) analysis. Polymerase chain reaction (PCR) was performed on a highly conserved region of M 16S rDNA and the amplicons were subjected to DGGE. The microbial community (MC) fingerprint was used to distinguish microbial populations. The intestinal contents incubated with GroBiotic-A had significantly (P<0.05) higher acetate and total VFA concentrations at 48 h compared to the other treatments. DGGE analysis demonstrated that the microbial community was significantly altered by Grobiotic-A and brewers yeast.     

Estimating plant-available nitrogen release from manures, composts, and specialty products

Recent adoption of national rules for organic crop production have stimulated greater interest in meeting crop N needs using manures, composts, and other organic materials. This study was designed to provide data to support Extension recommendations for organic amendments. Specifically, our objectives were to (i) measure decomposition and N released from fresh and composted amendments and (ii) evaluate the performance of the model DECOMPOSITION, a relatively simple N mineralization/immobilization model, as a predictor of N availability. Amendment samples were aerobically incubated in moist soil in the laboratory at 22 degrees C for 70 d to determine decomposition and plant-available nitrogen (PAN) (n = 44), and they were applied preplant to a sweet corn crop to determine PAN via fertilizer N equivalency (n = 37). Well-composted materials (n = 14) had a single decomposition rate, averaging 0.003 d(-1). For uncomposted materials, decomposition was rapid (>0.01 d(-1)) for the first 10 to 30 d. The laboratory incubation and the full-season PAN determination in the field gave similar estimates of PAN across amendments. The linear regression equation for lab PAN vs. field PAN had a slope not different from one and a y-intercept not different than zero. Much of the PAN released from amendments was recovered in the first 30 d. Field and laboratory measurements of PAN were strongly related to PAN estimated by DECOMPOSITION (r(2) > 0.7). Modeled PAN values were typically higher than observed PAN, particularly for amendments exhibiting high initial NH(4)-N concentrations or rapid decomposition. Based on our findings, we recommend that guidance publications for manure and compost utilization include short-term (28-d) decomposition and PAN estimates that can be useful to both modelers and growers.     

Determination of fine particulate semi-volatile organic material at three eastern U.S. sampling sites

Correct assessment of fine particulate carbonaceous material as a function of particle size is, in part, dependent on the determination of semi-volatile compounds, which can be lost from particles during sampling. This study gives results obtained for the collection of fine particulate carbonaceous material at three eastern U.S. sampling sites [Philadelphia, PA; Shenandoah National Park, VA; and Research Triangle Park (RTP), NC] using diffusion denuder technology. The diffusion denuder samplers allow for the determination of fine particulate organic material with no artifacts, due to the loss of semi-volatile organic particulate compounds, or collection of gas-phase organic compounds by the quartz filter during sampling. The results show that an average of 41, 43, and 59% of fine particulate organic material was lost as volatilized semi-volatile organic material during collection of particles on a filter at Philadelphia, RTP, and Shenandoah, respectively. The particle size distribution of carbonaceous material retained by a filter and lost from a filter during sampling was obtained for the samples collected at Philadelphia and Shenandoah. The carbonaceous material retained by the particles during sampling was found predominantly in particles smaller than 0.4 microm in aerodynamic diameter. In contrast, the semi-volatile organic material lost from the particles during sampling had a mass median diameter of approximately 0.5 microm.     

Second generation chemical mass balance source apportionment of sulfur oxides and sulfate at the Grand Canyon during the Project MOHAVE summer intensive

Receptor-based chemical mass balance (CMB) analysis techniques are designed to apportion species that are conserved during pollutant transport using conserved source profiles. The techniques will fail if non-conservative species (or profiles) are not properly accounted for in the CMB model. The straightforward application of the CMB model developed for Project MOHAVE using regional profiles resulted in a significant under-prediction of total sulfate oxides (SOx, SO2 plus fine particulate sulfate) for many samples at Meadview, AZ. In addition, for these samples the concentration of the inert tracer emitted from the MOHAVE Power Project (MPP), ocPDCH, was also under-predicted. A second-generation model has been developed which assumes that separation of particles and SO2 can occur in the MPP plume during nighttime stable plume conditions. This second-generation CMB model accounts for all SOx present at the various receptor sites. In addition, the concentrations of ocPDCH and the presence of other inert tracers of emission from regional sources are accurately predicted. The major source of SOx at Meadview was the MPP, but the major source of sulfate at this site was the Las Vegas urban area. At Hopi Point in the Grand Canyon, the Baja California region (Imperial Valley and northwestern Mexico) was the major source of both SOx and sulfate.     

Continuous determination of fine particulate matter mass in the Salt Lake City Environmental Monitoring project: a comparison of real-time and conventional TEOM monitor results

Fine particulate matter (PM2.5) mass was determined on a continuous basis at the Salt Lake City Environmental Protection Agency Environmental Monitoring for Public Awareness and Community Tracking monitoring site in Salt Lake City, UT, using three different monitoring techniques. Hourly averaged PM2.5 mass data were collected during two sampling periods (summer 2000 and winter 2002) using a real-time total ambient mass sampler (RAMS), sample equilibration system (SES)-tapered element oscillating microbalance (TEOM), and conventional TEOM monitor. This paper compares the results obtained from the various monitoring systems, which differ in their treatment of semivolatile material (SVM; particle-bound water, semivolatile ammonium nitrate, and semivolatile organic compounds). PM2.5 mass results obtained by the RAMS were consistently higher than those obtained by the SES-TEOM and conventional TEOM monitors because of the RAMS ability to measure semivolatile ammonium nitrate and semivolatile organic material but not particle-bound water. The SES-TEOM monitoring system was able to account for an average of 28% of the SVM, whereas the conventional TEOM monitor loses essentially all of the SVM from the single filter during sampling. Occasional mass readings by the various TEOM monitors that are higher than RAMS results may reflect particle-bound water, which, under some conditions, is measured by the TEOM but not the RAMS.     

Evaluation of the RAMS continuous monitor for determination of PM2.5 mass including semi-volatile material in Philadelphia,PA

The real-time ambient mass sampler (RAMS) is a continuous monitor based on particle concentrator, denuder, drier, and tapered element oscillating microbalance (TEOM) monitor technology. It is designed to measure PM2.5 mass, including the semi-volatile species NH4NO3 and semi-volatile organic material, but not to measure PM2.5 water content. The performance of the RAMS in an urban environment with high humidity was evaluated during the July 1999 NARSTO-Northeast Oxidant and Particles Study (NEOPS) intensive study at the Baxter water treatment plant in Philadelphia, PA. The results obtained with the RAMS were compared to mass measurements made with a TEOM monitor and to constructed mass obtained with a Particle Concentrator-Brigham Young University Organic Sampling System (PC-BOSS) sampler designed to determine the chemical composition of fine particles, including the semi-volatile species. An average of 28% of the fine particulate material present during the study was semi-volatile organic material lost from a filter during particle collection, and 1% was NH4NO3 that was also lost from the particles during sampling. The remaining mass was dominantly nonvolatile (NH4)2SO4 (31%) and organic material (37%), with minor amounts of soot, crustal material, and nonvolatile NH4NO3. Comparison of the RAMS and PC-BOSS results indicated that the RAMS correctly monitored for fine particulate mass, including the semivolatile material. In contrast, the heated filter of the TEOM monitor did not measure the semi-volatile material. The comparison of the RAMS and PC-BOSS data had a precision of +/-4.1 microg/m3 (+/-9.6%). The precision of the RAMS data was limited by the uncertainty in the blank correction for the reversible adsorption of water by the charcoal-impregnated cellulose sorbent filter of the RAMS monitor. The precision of the measurement of fine particulate components by the PC-BOSS was +/-6-8%.     

You want me to do what? Two daily diary studies of illegitimate tasks and employee well‐being

Illegitimate tasks, a recently introduced occupational stressor, are tasks that violate norms about what an employee can reasonably be expected to do. Because they are considered a threat to one's professional identity, we expected that the daily experience of illegitimate tasks would be linked to a drop in self‐esteem and to impaired well‐being. We report results of two daily diary studies, one in which 57 Swiss employees were assessed twice/day and one in which 90 Americans were assessed three times/day. Both studies showed that illegitimate tasks were associated with lowered state self‐esteem. Study 1 demonstrated that high trait self‐esteem mitigated that relationship. Study 2 showed that illegitimate tasks were associated with not only lowered state self‐esteem but also lower job satisfaction and higher anger and depressive mood, but not anger or job satisfaction remained elevated until the following morning. Copyright © 2015 John Wiley & Sons, Ltd.     

The Epa Program to Assess the Public Health Significance of Diesel Emissions

The U.S. Environmental Protection Agency's program to assess the public health significance of diesel emissions is described. The reasons for the EPA concern over diesel exhaust products are discussed. Some results of EPA research efforts over the last nine months are summarized and preliminary conclusions are drawn. Finally, the planned future health experiments which will hopefully fill some remaining gaps in our knowledge are identified.