Chloramine demand estimation using surrogate chemical and microbiological parameters

A model is developed to enable estimation of chloramine demand in full scale drinking water supplies based on chemical and microbiological factors that affect chloramine decay rate via nonlinear regression analysis method. The model is based on organic character (specific ultraviolet absorbance (SUVA)) of the water samples and a laboratory measure of the microbiological (F m ) decay of chloramine. The applicability of the model for estimation of chloramine residual (and hence chloramine demand) was tested on several waters from different water treatment plants in Australia through statistical test analysis between the experimental and predicted data. Results showed that the model was able to simulate and estimate chloramine demand at various times in real drinking water systems. To elucidate the loss of chloramine over the wide variation of water quality used in this study, the model incorporates both the fast and slow chloramine decay pathways. The significance of estimated fast and slow decay rate constants as the kinetic parameters of the model for three water sources in Australia was discussed. It was found that with the same water source, the kinetic parameters remain the same. This modelling approach has the potential to be used by water treatment operators as a decision support tool in order to manage chloramine disinfection.     

Occurrence and Trend of Hepatitis A Virus in Bivalve Molluscs Production Areas Following a Contamination Event

The aim of this study was to assess the trend of hepatitis A virus (HAV) in a coastal zone impacted by a contamination event, providing data for the development of management strategies. A total of 352 samples, including four bivalve mollusc species (Mytilus galloprovincialis, Solen vagina, Venus gallina and Donax trunculus), were taken over a period of 6 months from 27 production areas of the coast and analysis were performed according to ISO/TS 15216-1:2013. HAV presence was detected in 77 samples from 11 production areas and all positive results were related to samples collected in the first 3 months of the surveillance, during which HAV prevalence was 39.9% and values as high as 5096 genome copies/g were detected. A progressive reduction of viral contamination was evident during the first trimester of the monitoring, with prevalence decreasing from 78.8% in the first month, to 37.8% in the second and 3.9% in the third and quantitative levels reduced from an average value of 672 genome copies/g to 255 genome copies/g over a period of 4 weeks (virus half-life: 21.5 days). A regression analysis showed that, during the decreasing phase of the contamination, the data fitted a reciprocal quadratic model (Ra² = 0.921) and, based on the model, a residual presence of HAV could be estimated after negativization of the production areas. The statistical analysis of the results per shellfish species and per production area showed that there were limited differences in contamination prevalence and levels among diverse bivalve species, while a statistically significant difference was present in quantitative levels of one production area. These data could be useful for the development of both risk assessment models and code of practice for the management of viral contamination in primary production.     

Individual-based modeling of flooding and salinity effects on a coastal swamp forest

Coastal swamps are among the rapidly vanishing wetland habitats in Louisiana. Increased flooding, nutrient and sediment deprivation, and salt-water intrusion have been implicated as probable causes of the decline of coastal swamps. We developed a two-species individual-based forest succession model to compare the growth and composition of a cypress-tupelo swamp under various combinations of flooding intensity and salinity levels, using historical time-series of stage and salinity data as inputs. Our model simulates forest succession over 500 years by representing the growth, mortality, and reproduction of individual Taxodium distichum (baldcypress) and Nyssa aquatica (water tupelo) trees in a 1-km² spatial grid of 10 m × 10 m cells that vary in water levels and salinity through differences in elevation. We independently adjusted the elevations of each cell to obtain different grid-wide mean elevations and standard deviations of elevation; this affected the temporal and spatial pattern of flooding. We calibrated the model by adjusting selected parameters until averaged basal area, stem density and wood production rates under two different mean elevations (partially versus highly flooded) were qualitatively similar to comparable values reported for swamps in the literature. Corroboration involved comparing model predictions to four well-monitored contrasting habitat sites within the Maurepas Basin, Louisiana, USA. Model predictions of both species combined showed the same patterns among sites as the data, but the model overestimated wood production and the dominance of T. distichum. Exploratory simulations predicted that increased flooding leads to swamps with reduced basal areas and stem densities, while increased salinity resulted in lower basal areas at low salinity concentration (∼1-3 psu) and complete tree mortality at higher salinity concentrations (∼2-6 psu). Our model can provide insight into the succession dynamics of coastal swamps and information for the effective design of restoration actions.     

The role of humic non-exchangeable binding in the promotion of metal ion transport in groundwaters in the environment

Metal ions form strong complexes with humic substances. When the metal ion is first complexed by humic material, it is bound in an 'exchangeable' mode. The metal ion in this fraction is strongly bound, however, if the metal-humic complex encounters a stronger binding site on a surface, then the metal ion may dissociate from the humic substance and be immobilised. However, over time, exchangeably-bound metal may transfer to a 'non-exchangeable' mode. Transfer into this mode and dissociation from it are slow, regardless of the strength of the competing sink, and so immobilisation may be hindered. A series of coupled chemical transport calculations has been performed to investigate the likely effects of non-exchangeable binding upon the transport of metal ions in the environment. The calculations show that metal in the non-exchangeable mode will have a significantly higher mobility than that in the exchangeable mode. The critical factor is the ratio of the non-exchangeable first-order dissociation rate constant and the residence time in the groundwater column, metal ion mobility increasing with decreasing rate constant. A second series of calculations has investigated the effect of the sorption to surfaces of humic/metal complexes on the transport of the non-exchangeably bound metal. It was found that such sorption may reduce mobility, depending upon the humic fraction to which the metal ion is bound. For the more weakly sorbing humic fractions, under ambient conditions (humic concentration etc.) the non-exchangeable fraction may still transport significantly. However, for the more strongly sorbed fractions, the non-exchangeable fraction has little effect upon mobility. In addition to direct retardation, sorption also increases the residence time of the non-exchangeable fraction, giving more time for dissociation and immobilisation. The non-exchangeable dissociation reaction, and the sorption reaction have been classified in terms of two Damkohler numbers, which can be used to determine the importance of chemical kinetics during transport calculations. These numbers have been used to develop a set of rules that determine when full chemical kinetic calculations are required for a reliable prediction, and when equilibrium may be assumed, or when the reactions are sufficiently slow that they may be ignored completely.     

Bicyclist fatalities involving heavy goods vehicles: gender differences in risk perception, behavioral choices, and training

Objectives: Females are typically involved in fewer collisions when pedal cycling than males. However, female cyclists appear to be overrepresented in the number of fatal collisions involving heavy goods vehicles (HGVs). These collisions often involve cyclists passing HGVs on the side furthest from the HGV driver (nearside). It is hypothesized that this pattern of fatalities may be partly due to differences in how males and females perceive the risk associated with various cycling maneuvers. It is also hypothesized that this difference may be overcome with advanced training. Methods: 4,596 UK cyclists completed an online questionnaire in which they reported their level of cycle training and rated the risk they perceived to be associated with various cycling maneuvers, the likelihood that they would engage in them, and history of collision involvement. Results: Females perceived a slightly greater level of risk to be associated with cycling. However, males differentiated between the risks involved in nearside and offside overtaking to a greater extent than females. Risk perception was significantly correlated with the reported likelihood that participants would engage in risky maneuvers such as overtaking on the nearside and also with past collision prevalence. Advanced cycling training was correlated with higher levels of perceived risk associated with overtaking on the nearside; however, basic cycle training was not. Conclusions: Cyclists who do not correctly differentiate between the risks associated with nearside and offside overtaking may be more at risk of being involved in HGV-related collisions. Advanced cycling training is linked to more accurate risk perception. To reduce fatalities, public awareness campaigns should focus on the increased risk of nearside overtaking and encourage cyclists to take advanced training.     

Large-scale diversity and biogeography of benthic copepods in European waters

A large-scale database concerning benthic copepods from the Arctic, Baltic Sea, North Sea, British Isles, Adriatic Sea and Crete was compiled to assess species richness, biodiversity, communities, ecological range size and biogeographical patterns. The Adriatic showed the highest evenness and the most species-rich communities. Assemblages from the North Sea, British Isles, Baltic and Crete had a lower evenness. The British Isles were characterised by impoverished communities. The ecological specificity of copepod species showed two diverging trends: higher specificity of species in more diverse assemblages was observed in the Adriatic, North Sea and Baltic. A uniformly high species specificity disregarding sample diversity was found on Crete and in the British Isles. Benthic copepod communities showed distinct patterns that clearly fit the predefined geographical regions. Communities were distinguishable and β-diversity was found to be high around Europe, indicating a high species turnover on the scale of this investigation. The British Isles and the North Sea were found to be faunistic links to the Baltic and the Arctic.     

Burden or blessing? Expected costs and benefits of being a mentor

We investigated the relationship between anticipated costs and benefits of being a mentor, mentoring experience, and intentions to mentor among a sample of 275 executives. Individuals lacking mentoring experience anticipated greater costs and fewer benefits than experienced individuals. Anticipated costs and benefits were related to intentions to mentor, and this relationship varied by mentoring experience. The results suggest that mentoring may be an intergenerational process. Copyright © 1999 John Wiley & Sons, Ltd.     

Climate change and disaster management

Climate change, although a natural phenomenon, is accelerated by human activities. Disaster policy response to climate change is dependent on a number of factors, such as readiness to accept the reality of climate change, institutions and capacity, as well as willingness to embed climate change risk assessment and management in development strategies. These conditions do not yet exist universally. A focus that neglects to enhance capacity-building and resilience as a prerequisite for managing climate change risks will, in all likelihood, do little to reduce vulnerability to those risks. Reducing vulnerability is a key aspect of reducing climate change risk. To do so requires a new approach to climate change risk and a change in institutional structures and relationships. A focus on development that neglects to enhance governance and resilience as a prerequisite for managing climate change risks will, in all likelihood, do little to reduce vulnerability to those risks.     

Evolution of iron speciation during hydration of C4AF

It is now well accepted and demonstrated that calcium silicate, calcium aluminate and calcium sulfo aluminate (ettringite, AFm) phases exhibit a good capability to fix metals and metalloids. Unfortunately the role of minor phases and especially calcium-ferric aluminate phase, shorthand C4AF is not well defined. In other systems like in soils or sediments iron phases play a key role in the fixation of pollutant. In cement sorption isotherms, indicated that various metals can be retained by the C4AF hydrated products. Therefore the capabilities of those phase to retain heavy metal should not be neglected. Previous investigations have shown that the minerals formed during the hydration of C4AF are similar to those formed from C3A (pure tri-calcium aluminate) under comparable conditions. Nevertheless no investigation was conducted at the molecular level and there is still a controversy whether Fe substitutes for Al in the hydrated minerals in whole or in part, or if it forms FeOOH clusters scattered throughout the matrix. In this context we have conducted XAS experiments using synchrotron radiation. It was found that the hydration of C4AF forms C3AH6 (hydrogarnet) in which Fe randomly substitutes for Al as well as an amorphous FeOOH phase. Intermediate products like AFm (i.e., an ill organized lamellar phase) are also formed but rapidly evolve to C3AH6; iron does not seem to be incorporated in the AFm structure.     

The case for policy‐relevant conservation science

Drawing on the “evidence‐based” (Sutherland et al. 2013) versus “evidence‐informed” debate (Adams & Sandbrook 2013), which has become prominent in conservation science, I argue that science can be influential if it holds a dual reference (Lentsch & Weingart 2011) that contributes to the needs of policy makers whilst maintaining technical rigor. In line with such a strategy, conservation scientists are increasingly recognizing the usefulness of constructing narratives through which to enhance the influence of their evidence (Leslie et al. 2013; Lawton & Rudd 2014). Yet telling stories alone is rarely enough to influence policy; instead, these narratives must be policy relevant. To ensure that evidence is persuasive alongside other factors in a complex policy‐making process, conservation scientists could follow 2 steps: reframe within salient political contexts and engage more productively in boundary work, which is defined as the ways in which scientists “construct, negotiate, and defend the boundary between science and policy” (Owens et al. 2006:640). These will both improve the chances of evidence‐informed conservation policy.