Patterns and drivers of forest land cover changes in tropical semi-deciduous forests in Ghana

This study was conducted to determine the patterns and drivers of forest land cover changes in Bobiri and Oboyow Forest Reserves (BFR and OFR, respectively), Ghana. Landsat images were employed to determine forest land cover types and changes in 1990, 2000 and 2010 using supervised classification method. Factors that drive forest land cover changes in the forest reserves were determined using a semi-structured questionnaire and field observations. Generally, closed-canopy forest decreased by 49% in both forests over 20-year period resulting in a tremendous increase in open-canopy forest (BFR: 85%; OFR: 46%) and non-forest land cover types (BFR: 48–80% OFR: 127–350%). Factors such as logging manual illiteracy among timber operators, offences of authorised timber operators, ineffective community participation, harvesting schedule revision, chainsaw logging, illegal logging, bushfires, fuel gathering and weak penalty for offences were identified as contributing to rapid depletion of closed canopy forest cover in the forest reserves.     

Monitoring of genetically modified Escherichia coli in laboratory wastewater

Containment of genetically modified (GM) microorganisms such as Escherichia coli is a legal requirement to protect the environment from an unintended release and to avoid horizontal gene transfer (HGT) of recombinant DNA to native bacteria. In this study, we sampled the laboratory wastewater (LWW) at a large Swiss university from three sources over 2 years and cultured ampicillin-resistant, presumptive GM E. coli. From a total of 285 samples, 127 contained presumptive GM E. coli (45%) at a mean concentration of 2.8 × 10² CFU/ml. Plasmid DNA of 11 unique clones was partially or entirely sequenced. All consisted of cloning vectors harboring research-specific inserts. To estimate the chance of HGT between GM E. coli and native bacteria in LWW, we identified taxa representative for the bacterial community in LWW using 16S rRNA amplicon sequencing and measured conjugation frequencies of E. coli with five LWW isolates. At optimal conjugation conditions, frequencies were between 3.4 × 10⁻³ and 2.4 × 10⁻⁵. Given the absence of transferable broad-host range plasmids and suboptimal conjugation conditions in the LWW system, we conclude that the chance of HGT is relatively low. Still, this study shows that the implementation of robust containment measures is key to avoid the escape of GM microorganisms.

     

Phosphine by bio-corrosion of phosphide-rich iron

Phosphine is a toxic agent and part of the phosphorus cycle. A hitherto unknown formation mechanism for phosphine in the environment was investigated. When iron samples containing iron phosphide were incubated in corrosive aquatic media affected by microbial metabolites, phosphine was liberated and measured by gas chromatography. Iron liberates phosphine especially in anoxic aquatic media under the influence of sulfide and an acidic pH. A phosphine-forming mechanism is suggested: Phosphate, an impurity of iron containing minerals, is reduced abioticly to iron phosphide. When iron is exposed to the environment (e.g. as outdoor equipment, scrap, contamination in iron milled food or as iron meteorites) and corrodes, the iron phosphide present in the iron is suspended in the medium and can hydrolyze to phosphine. Phosphine can accumulate to measurable quantities in anoxic microbial media, accelerating corrosion and preserving the phosphine formed from oxidation.     

Explaining nursing turnover intent: job satisfaction,pay satisfaction,or organizational commitment?

A number of models have been developed to explain nurses' turnover behavior. The common theme that emerges from these models is that turnover behavior is a multistage process that includes attitudinal, decisional, and behavioral components. The purpose of this study was to assess both the direct and indirect impact of certain pay policies upon the turnover intentions of paediatric nurses. The two major questions addressed were: What was the relative impact of job satisfaction, pay satisfaction, and organizational commitment upon the turnover intentions of paediatric nurses eligible for these pay policies? What model accurately portrays the relationship among these three independent variables and turnover intentions? Exploration of the causal pathways among these variables and demographic factors revealed complex models of association. The results suggest that job satisfaction has only an indirect influence on the intention to quit, whereas organizational commitment has the strongest and most direct impact. A further finding that pay satisfaction had both direct and indirect effects on turnover intent was consistent with administrators' assumptions underlying the pay policies. Control variables such as having a degree, having children, and working 12-hour shifts were found to have both direct and indirect influences upon pay satisfaction and turnover intent. © 1998 John Wiley & Sons, Ltd.     

Estimating the relevance of engineered carbonaceous nanoparticle facilitated transport of hydrophobic organic contaminants in porous media

Naturally occurring nanoparticles (NP) enhance the transport of hydrophobic organic contaminants (HOCs) in porous media. In addition, the debate on the environmental impact of engineered nanoparticles (ENP) has become increasingly important. HOC bind strongly to carbonaceous ENP. Thus, carbonaceous ENP may also act as carriers for contaminant transport and might be important when compared to existing transport processes. ENP bound transport is strongly linked to the sorption behavior, and other carbonaceous ENP-specific properties. In our analysis the HOC-ENP sorption mechanism, as well as ENP size and ENP residence time, was of major importance. Our results show that depending on ENP size, sorption kinetics and residence time in the system, the ENP bound transport can be estimated either as (1) negligible, (2) enhancing contaminant transport, or (3) should be assessed by reactive transport modeling. One major challenge to this field is the current lack of data for HOC-ENP desorption kinetics.     

Increasing stair climbing in a train station: The effects of contextual variables and visibility

Accumulation of physical activity during daily living is a current public health target that is influenced by the layout of the built environment. This study reports how the layout of the environment may influence responsiveness to an intervention. Pedestrian choices between stairs and the adjacent escalators were monitored for 7 weeks in a train station (Birmingham, UK). After a 3.5 week baseline period, a stair riser banner intervention to increase stair climbing was installed on two staircases adjacent to escalators and monitoring continued for a further 3.5 weeks. Logistic regression analyses revealed that the visibility of the intervention, defined as the area of visibility in the horizontal plane opposite to the direction of travel (termed the isovist) had a major effect on success of the intervention. Only the largest isovist produced an increase in stair climbing. Additionally, stair climbing was more common during the morning rush hour and at higher levels of pedestrian traffic volume. The layout of the intervention site can influence responsiveness to point-of-choice interventions. Changes to the design of train stations may maximize the choice of the stairs at the expense of the escalator by pedestrians leaving the station.     

Exposure to ultrafine and fine particles and noise during cycling and driving in 11 Dutch cities

Recent studies have suggested that exposures during traffic participation may be associated with adverse health effects. Traffic participation involves relatively short but high exposures. Potentially relevant exposures include ultrafine particles, fine particles (PM_2.5) and noise.Simultaneously, detailed real time exposure of particle number concentration (PNC), PM_2.5 and noise has been measured while driving and cycling 12 predefined routes of approximately 10–20 min duration. Sampling took place in eleven medium-sized Dutch cities on eleven weekdays in August till October 2006. To investigate variability in cyclists exposure, we systematically collected information on meteorology, GPS coordinates, type of road, traffic intensity, passing vehicles and mopeds while cycling.The overall mean PNC of car drivers was 5% higher than the mean PNC of cyclists. The overall mean concentration of PM_2.5 in the car was 11% higher than during cycling. Slightly higher 1-min peak concentrations were measured in the car (PNC 14%; PM_2.5 29% for 95-percentiles). Shorter duration peaks of PNC were higher during cycling (43% for 99-percentile of 1-s averages). Peaks in PNC typically last for less than 10 s. A large variability of exposure was found within and between routes. Factors that significantly predicted PNC variability during cycling were: passing vehicles (mopeds, cars), waiting for traffic lights, passing different types of (large) intersections and bicycle lanes and bike paths close to motorized traffic. No relation was found between PM_2.5 and those predictor variables. The correlation between PNC and noise was moderate (median 0.34). PM_2.5 had very low correlations with PNC and noise.PNC and PM_2.5 exposure of car drivers was slightly higher than that of cyclists. PNC was largely uncorrelated with PM_2.5 and reflected local traffic variables more than PM_2.5. Different factors were associated with high PNC and high noise exposures.     

Traffic mortality and the role of minor roads

Roads have large impacts on wildlife, as they form one of the principal causes of mortality, and disturbance and fragmentation of habitat. These impacts are mainly studied and mitigated on major roads. It is, however, a widespread misconception that most animals are killed on major roads. In this paper, we argue that minor roads have a larger impact on wildlife with respect to habitat destruction, noise load and traffic mortality. We use data on traffic related deaths in badgers (Meles meles) in The Netherlands to illustrate that traffic mortality is higher on minor roads. We ask for a more extensive investigation of the environmental impacts of minor roads. Moreover, we argue that the success of mitigation on roads drastically increases when both major and minor roads are integrated in the planning of traffic flows. Therefore, we propose a strategy based on the concept of a "traffic-calmed area". Traffic-calmed areas create opportunities for wildlife by decreasing limitations for animal movement. We ask for further studies to estimate what size traffic-calmed areas should be to maintain minimum viable animal populations.     

The Use of Atmospheric Dispersion Models in Risk Assessment Decision Support Systems for Pesticides

In the evaluation of potentially adverse effects oforganic chemicals such as pesticides on theenvironment the atmosphere may play an important role.After its release to the atmosphere the chemical willbe transported/dispersed in the atmosphere and finallyit will be removed either by atmospheric-chemicaldestruction or by deposition to the underlying soil orsurface water. In a risk assessment decision supportsystem both ambient concentrations and depositionfluxes must be known to evaluate the risk of directexposure (inhalation) or the risk of soil and watercontamination caused by deposition. This paperdiscusses the use of atmospheric dispersion models insuch risk assessment decision support systems.     

Compost impacts on dissolved organic carbon and available nitrogen and phosphorus in turfgrass soil

Compost application to turfgrass soils may increase dissolved organic C (DOC) levels which affects nutrient dynamics in soil. The objectives of this study were to investigate the influence of compost source and application rate on soil organic C (SOC), DOC, NO(3), and available P during 29 months after a one-time application to St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] turf. Compost sources had variable composition, yet resulted in few differences in SOC, DOC, and NO(3) after applied to soil. Available NO(3) rapidly decreased after compost application and was unaffected by compost source and application rate. Available P increased after compost application and exhibited cyclical seasonal patterns related to DOC. Compost application decreased soil pH relative to unamended soil, but pH increased during the course of the study due to irrigation with sodic water. Increasing the compost application rate increased SOC by 3 months, and levels remained fairly stable to 29 months. In contrast, DOC continued to increase from 3 to 29 months after application, suggesting that compost mineralization and growth of St. Augustinegrass contributed to seasonal dynamics. Dissolved organic C was 75%, 78%, and 101% greater 29 months after application of 0, 80, and 160 Mg compostha(-1), respectively, than before application. Impacts of composts on soil properties indicated that most significant effects occurred within a few months of application. Seasonal variability of SOC, DOC, and available P was likely related to St. Augustinegrass growth stages as well as precipitation, as declines occurred after precipitation events.