The contribution of biological particles to observed particulate organic carbon at a remote high altitude site

Although a significant fraction of atmospheric particulate mass is organic carbon, the sources of particulate organic carbon (POC) are not always apparent. One potential source of atmospheric POC is biological particles, such as bacteria, pollen, and fungal spores. Measurements of POC and biological particles, including bacteria, fungal spores, and pollen, were made as part of the Storm Peak Aerosol and Cloud Characterization Study in Steamboat Springs, CO in March–April 2008. Biological particles were identified and characterized using several methods. The results suggest that biological particles could account for an average of 40% of the organic carbon mass in particles with aerodynamic diameters less than 10 μm. These estimates of POC mass from biological particles are highly uncertain; however, the results suggest that biological particles could be a significant source of organic aerosol in the background continental atmosphere and further observations are needed to better constrain these estimates.     

Exposure to fall hazards and safety climate in the aircraft maintenance industry

PROBLEM: Falls represent a significant occupational hazard, particularly in industries with dynamic work environments. This paper describes rates of noncompliance with fall hazard prevention requirements, perceived safety climate and worker knowledge and beliefs, and the association between fall exposure and safety climate measures in commercial aircraft maintenance activities. METHODS: Walkthrough observations were conducted on aircraft mechanics at two participating facilities (Sites A and B) to ascertain the degree of noncompliance. Mechanics at each site completed questionnaires concerning fall hazard knowledge, personal safety beliefs, and safety climate. Questionnaire results were summarized into safety climate and belief scores by workgroup and site. Noncompliance rates observed during walkthroughs were compared to the climate-belief scores, and were expected to be inversely associated. RESULTS: Important differences were seen in fall safety performance between the sites. The study provided a characterization of aircraft maintenance fall hazards, and also demonstrated the effectiveness of an objective hazard assessment methodology. Noncompliance varied by height, equipment used, location of work on the aircraft, shift, and by safety system. DISCUSSION: Although the expected relationship between safety climate and noncompliance was seen for site-average climate scores, workgroups with higher safety climate scores had greater observed noncompliance within Site A. Overall, use of engineered safety systems had a significant impact on working safely, while safety beliefs and climate also contributed, though inconsistently. IMPACT ON INDUSTRY: The results of this study indicate that safety systems are very important in reducing noncompliance with fall protection requirements in aircraft maintenance facilities. Site-level fall safety compliance was found to be related to safety climate, although an unexpected relationship between compliance and safety climate was seen at the workgroup level within site. Finally, observed fall safety compliance was found to differ from self-reported compliance.     

Ground cover impacts on nitrogen export from manured riparian pasture

Maintaining ground cover of forages may reduce the export of nitrogen (N) from pastures. The objective of this work was to determine the effect of ground cover on N export from pastured riparian areas receiving simulated rainfall. Plots were established on two adjacent sites in the North Carolina Piedmont: one of 10% slope with Appling sandy loam soils and a second of 20% slope with Wedowee sandy loam soils. Both sites had existing mixed tall fescue (Festuca arundinacea Schreb.)-dallisgrass (Paspalum dilatatum Poir.) vegetation. Forage stands were modified to represent a range of ground cover levels: 0, 45, 70, and 95% (bare ground, low, medium, and high cover, respectively), and amended with beef steer (Bos taurus) feces and urine (approximately 200 kg N ha-1). For all rain events combined, mean nitrate N export was greatest from bare ground and was reduced by 34% at low cover, which did not differ from high cover. Mean ammonium N export was slightly elevated (approximately 1.37 kg N ha-1) in months when manures were applied and negligible (<0.02 kg N ha-1) in all other months. For all rain events combined, mean export of total N was greatest from bare ground and was reduced by at least 85% at all other cover levels. Whereas site did not impact N export, results indicated that cover and time of rainfall following manure deposition are important determinants of the impact of riparian grazing.     

Enhanced in situ bioremediation of phenol in bioestimulated unsaturated and saturated sand-bed columns.

Biodegradation of phenol was observed in unsaturated sandbed columns, in which phenol concentration declined from 298 mg phenol/kg sand to less than 1 mg/kg after 21 days. In saturated sand-bed columns, phenol concentration declined from 230 mg phenol/kg to less than 1 mg/kg after 37 days. Pseudo-first-order phenol biodegradation rates were in the range 0.25 days(-1) (R2 = 0.9) to 0.66 days(-1) (R2 = 0.85) and 0.08 days(-1) (R2 = 0.68) to 0.14 days(-1) (R2 = 0.84) in the unsaturated and saturated sand-bed columns, respectively. Unsaturated columns presented a higher biomass density (21.5 mg/g) in the sand-bed and lower biomass concentration in the aqueous phase (3.5 NTU) compared with the saturated columns (6.4 mg/g and 14.0 NTU). A high concentration of phenol releases in the sand-bed columns resulted in an initial inhibition of microbial activity and destabilization of the attached biomass.     

Copper-binding efficacy of water-soluble chitosans: characterization by aqueous binding isotherms

The major objective of the study is to measure directly the isotherms of copper binding onto soluble chitosan preparations, using ion-selective electrode technique. Copper uptake is found to decrease strongly when chitosan acetylation degree or chitosan concentration increased. When relating the bound copper concentrations to content of non-acetylated amine groups in a chitosan, differences between copper uptake on different chitosan preparations become reduced but not disappear. Other effects, in addition to the contents of non-acetylated amine groups, can involve differences in the copper binding by different chitosans. Due to isotherm non-linearity, the distribution coefficient K(d) of copper between a water-soluble chitosan and an aqueous solution may vary by two orders of magnitude as the free copper concentration C(free) varied. Linear relation between logK(d) normalized by free amine group content of chitosans and logC(free) may help in preliminary estimating of the copper binding by water-soluble chitosans at a certain pH.     

The effect of perceived intruder proximity and resident body size on the aggressive responses of male green frogs, Rana clamitans (Anura: Ranidae)

We examined variation in aggressive responses within and among individuals in the green frog, Rana clamitans. We tested the hypothesis that resident males respond in a graded fashion to changes in perceived intruder proximity (stimulus intensity). We also investigated how response level varied with responder body size. We found that green frogs differentially alter aggressive responses (increasing movement and calling rates while decreasing the duration and dominant frequency of their calls) with an increase in stimulus intensity. Body size did not appear to be a significant influence on most response levels. We suggest that aggressive responses are graded, and advertisement and aggressive calls represent opposite ends of a continuum. Green frogs do not exhibit clearly defined thresholds for responses like those reported for some other frogs. By using graded responses rather than discrete all-or-nothing responses, males may reduce the potential costs of aggressive encounters.     

Peak exposures in aluminium potrooms: instrument development and field calibration

Aluminium smelter potrooms are unique in that workplace exposures to hydrogen fluoride (HF), sulfur dioxide (SO2), and particulate matter occur simultaneously for some tasks. The peak exposures to these contaminants are of increasing interest in discovering the etiology of respiratory health effects. While a variety of direct-reading instruments are available for sulfur dioxide and particulate matter, only a few exist for hydrogen fluoride. The sensors in these HF instruments have a cross-sensitivity to sulfur dioxide making it difficult to monitor HF in an environment that also contains SO2. To overcome this problem, we assessed the simultaneous use of two electrochemical instruments: one with a SO2 sensor that does not respond to HF and the second with a hydrogen fluoride sensor that responds to both HF and SO2 in a 1 : 1 ratio, termed 'total acid gas'. The difference in the response between the two instruments should indicate the HF concentration: [HF + SO2] minus SO2 equals HF. The performance characteristics of this sampling train were evaluated in the laboratory through the generation of both HF and SO2 with permeation tubes. The response and recovery times for the SO2 only instrument were acceptable (6 and 15 s, respectively), but the "total acid gas" instrument exhibited both slow response and slow recovery approaching three and six min. The association between the traditional integrated filter sampling method and the direct-reading instrument for SO2 is 0.80 (Spearman's rho). The use of the digital filter strengthens the association between the HF direct-reading instrument and the integrated samples from 0.41 to 0.68.     

The use of seat belt by motor vehicle occupants in South Africa

OBJECTIVE: The purpose of this article was to examine the use of seat belt by motor vehicle users in the various provinces in South Africa. METHODS: Data were abstracted from published reports of the national Department of Transport. Percentage distribution and correlation of road safety variables and seat belt wearing rates for motor vehicle users were calculated for the different provinces. RESULTS: High seat belt wearing rates by the drivers (between 75.1% and 88.1%, national rate was 81%). The seat belt wearing rates for the front and back seat passengers were much lower than for the drivers. The seat belt wearing rates for front seat passengers (44.5% to 60.5%, national - 50.1%) and back seat passengers (1% to 16%, national - 7.6%) were much lower than for the drivers. The national seat belt wearing rate for all vehicles between 1982 and 1995 was between 46.9% and 69.2%, but this has generally declined. CONCLUSION: There is a need for the implementation of strategies to increase the use of seat belts to reduce injuries and fatalities.     

Runoff water quality from manured riparian grasslands with contrasting drainage and simulated grazing pressure

Globally, management of grazed riparian areas is critically important to agricultural sustainability and environmental quality. However, the potential impacts of riparian grazing management on water quality are not well-documented, particularly in the southeastern USA. The objective of this work was to determine sediment and nutrient export under simulated rainfall from poorly drained and well-drained riparian soils where heavy or light grazing pressure by cattle was simulated. Plots were established on stands of existing vegetation to create grazing pressure treatments of (a) light-use (full ground cover, uncompacted), and with stands modified to establish (b) heavy-use (bare ground, compacted) treatments. Vegetation on poorly drained soils consisted of several typical wetland species (e.g., Pontederia cordata L., Juncus coriaceus Mackenzie) in the southeastern USA, whereas mixed tall fescue (Festuca arundinacea Schreb.)–dallisgrass (Paspalum dilatatum Poir.) stands were the dominant vegetation on well-drained soils. Runoff volume was generally greater from heavy-use than from light-use for poorly drained soils and for well-drained soils. Greater runoff volume was also observed from poorly drained soils compared to well-drained soils for both light-use and for heavy-use treatments. Light-use plots were remarkably effective at minimizing export of total suspended solids (TSS) on both soils (<30 kg ha⁻¹). Mean total Kjeldahl P (TKP) export was fourfold greater from heavy-use plots than from light-use plots on both soils. While export of nitrate-nitrogen (NO₃-N) was unaffected by grazing pressure and soil drainage, mean ammonium-nitrogen (NH₄-N) and total N (TN) export from poorly drained heavy-use plots was greater than fivefold that from well-drained light-use plots. Results indicate that livestock heavy-use areas in the riparian zone may export substantial TSS and nutrients, especially on poorly drained soils. However, when full ground cover is maintained on well-drained soils, TSS and nutrient losses may be limited.     

A qualitative systematic review of governance principles for mangrove conservation

Management of mangrove ecosystems is complex, given that mangroves are both terrestrial and marine, often cross regional or national boundaries, and are valued by local stakeholders in different ways than they are valued on national and international scales. Thus, mangrove governance has had varying levels of success, analyzed through concepts such as principles of good governance and procedural justice in decision-making. Although there is substantial research on case studies of mangrove management, global comparisons of mangrove governance are lacking. This research aims to fill this gap by comparing relationships among qualities of governance across mangrove social-ecological systems worldwide. Through a systematic literature search and screening process, we identified 65 articles that discussed mangrove governance and conservation. Case studies in these articles, drawn from 39 countries, were categorized as top-down, bottom-up, or comanaged and thematically coded to assess the influence of eight principles of good governance in mangrove conservation success. Across all three governance systems, the principles of legitimacy, fairness, and integration were most important in determining conservation success or failure. These principles are closely related to the concept of procedural justice, highlighting the importance of stakeholder inclusion throughout all stages of mangrove management. Thus, we recommend clearly defined roles for all governance actors, transparent communication of policy development to stakeholders, fairness in both process and outcome, and careful consideration of sustainable access to conservation resources.