The solution phase complexing of atrazine by fulvic acid: Equilibria at 25°c

Abstract

The solution phase complexing equilibria of atrazine by fulvic acid at 25°C±1.° have been investigated over the pH range of 1.3 to 6.0. Experiments with 0.1MKC1 and chelated Cu(II) are compared with those without metal ions. The use of a fulvic acid having calibrated acidic and Cu(II) chelation properties has made it possible to obtain stoicheometricly “exact”; chemical information. This is correlated with previous hydrolysis kinetics work. It is concluded that atrazine is hydrogen bonded in a labile equilibrium, to an identifiable set of protonated carboxyl groups, which act as Brönsted acid catalysts for hydrolysis. 0.1M KC1 changes (1‐α_A), the degree of protonation of the carboxyl groups, without otherwise affecting the atrazine complexing. Cu(II) chelation both reduces and weakens the complexing through a combination of carboxyl group blocking, and fulvic acid aggregation. Simple equations are presented for predictive calculations.     

Dancing Stories: A Community Dance Residency in a Hospice in New Zealand

Canoes forging through cold waters, mountains rising from the sea, a heart beating under a mountain lake, an albatross sailing toward the Antarctic: these were the story-images of Coastal Mappings, a large-scale community project set in and around Dunedin, New Zealand. In the Coastal Mappings performance project, people in the last months of their lives joined cancer survivors, family members and other interested people in explorations of Pakeha myths (by European-settler descendents) and Maori myths (by descendents of the crews of the first canoes, first inhabitants of New Zealand). Together, we created personal landscapes through movement, storytelling, photography and video. In this essay, I discuss some of the opportunities, challenges and experiences of leading a community dance project in an intercultural social environment, and with people whose relationship to their environment is different from mine.     

Measuring Road Traffic Safety Performance: Monitoring Trends in Nonfatal Injury

Traditional indicators used to monitor trends in nonfatal injury are influenced by a range of factors other than the incidence of injury. Indicators based on threat-to-life scales offer a means of addressing this problem. The aim of the research described in this article was to compare trends in the official indicators with trends in selected threat-to-life indicators. We compared indicators based on the New Injury Severity Score and the International Classification of Diseases–based Injury Severity Score with the official New Zealand indicators; namely, (1) reported injuries, (2) reported injuries per 10,000 vehicles, (3) reported injuries per 100,000 people, and (4) number hospitalized (discharges). All the official indicators suggest that there has been a substantive decline in nonfatal Motor Vehicle Traffic Crashes (MVTCs) for the period 1988–2000, but a notable increase in 2001. The latter appear to be artifactual increases due to changes in patterns of data collection and do not reflect any real changes in incidence. Further support for this is provided by the results for the two threat-to-life indicators, which suggest that the decline observed for 1988–98 may have been attributable to a decline in the ascertainment or occurrence of minor injuries since those injuries, which represent a significant threat to life, have not declined to the same degree. Given the prominence of motor vehicle crashes as a cause of unnecessary morbidity, more thought needs to be given to deriving valid indicators for measuring trends in serious nonfatal injury.     

Metals removal from aqueous solution by iron-based bonding agents

GOAL AND SCOPE AND BACKGROUND: The application of a promising method, termed sorptive flotation, for the removal of chromium(VI) and zinc ions was the aim of the present paper. A special case of sorptive flotation is adsorbing colloid flotation. Suitable sorbent preparation techniques have been developed in the laboratory. METHODS: Sorptive flotation, consisting of the sorption and flotation processes combined in series, has proved to give fast and satisfactory treatment of the industrial streams and effluents bearing dilute aqueous solutions of zinc and chromium(VI). RESULTS AND DISCUSSION: Goethite has proved to be effective for the removal of chromium(VI) and zinc ions. Also, adsorbing colloid flotation with ferric hydroxide (as the co-precipitant) could be an alternative method to the above-mentioned separation of metal ions. In both cases, chromium(VI) (pH=4) and zinc (pH=7) removal was about 100%. CONCLUSION: The reasons for selecting the iron-based bonding materials, like goethite and/or in-situ produced ferric hydroxide, are that they are cheap, easily synthesized, suitable both for cation and anion sorption, and, furthermore, that they present low risks for adding a further pollutant to the system. Promising results were obtained. RECOMMENDATION AND OUTLOOK: The application of goethite and in-situ produced ferric hydroxide has demonstrated their effectiveness in the removal of heavy metal ions, such as chromium anions and zinc cations. A proposed continuation of current work is the utilization of similar iron oxides, for instance synthesized akaganeite. The comparison between the results reported in this paper with the results reported in the literature, also deserves attention.     

Incorporation of biological information in water quality planning

Progress toward the goal of restoring integrity to the waters in the United States has been difficult to assess. This difficulty may arise from the type of regulatory policy that has been traditionally used. With the advent of widespread wastewater treatment, the use of a planning approach employing receiving water impact standards may offer a more practical and direct means of defining and assessing integrity. Biological community response is shown to offer an integrated approach to implementing and evaluating water quality management policy. The state of Maine (USA) has revised its water quality law by utilizing biological community response to assess integrity. This law is presented as a model that employs impact measures and a planning approach for the implementation of water quality management policy.     

On the use of criteria based on the SMART acronym to assess quality of performance indicators for safety management in process industries

Management of safety, and barriers in particular, includes using information expressing performance, i.e. use of safety performance indicators. For this information to be useful, the indicators should demonstrate adequate quality. In other words, they should satisfy some predefined set of quality criteria. Without showing adequate quality, the indicators are generally unable to provide sufficient support for barrier management, which could result in poor decisions. In this article, the use of the SMART criteria is considered to assess the quality of safety performance indicators in process industries. SMART being an acronym for ‘specificity’, ‘measurability’ or ‘manageability’, ‘achievability’, ‘relevancy’ and ‘time-based’, covering five key aspects and criteria for assessing the quality of an indicator. A discussion on whether the indicators are able to demonstrate adequate quality by satisfying these criteria has been conducted. The finding is that all of the SMART criteria should be satisfied for a safety performance indicator to demonstrate acceptable quality and to be regarded as useful to support barrier management decision-making. However, it has also been observed that including the ‘M’ criterion in the assessment of quality is not needed. When all the other criteria are satisfied there is no way the conclusions could be misleading as a result of measurability or manageability aspects. Hence, for safety performance indicator quality, only four of the criteria are assessed and suggested for such situations to shorten the acronym to ‘STAR’. A key safety indicator used in downstream process facilities, i.e. ‘dangerous fluid overfilling events’, motivated from the 2005 Texas City refinery accident, is used to illustrate the situation. The indicator is also applied to another incident, the Buncefield oil storage depot's accident in 2005, to provide a broader context for using it. The findings in this article could also be applied beyond the context studied. This means that, despite focusing on safety indicators in the process industries, the findings are considered as relevant and applicable to other types of performance indicators and to other energy industries.     

Development of pedestrian- and vehicle-related safety performance functions using Bayesian bivariate hierarchical models with mode-specific covariates

Introduction: Pedestrian safety is a major concern as traffic crashes are the leading cause of fatalities and injuries for commuters. Traffic safety research in the past has developed various strategies to counteract traffic crashes, including the safety performance function (SPF). However, there is still a need for research dedicated to enhancing the SPF for pedestrians from perspectives of methodological framework and data input. To fill this gap, this study aims to add to the current SPF development practice literature by focusing on pedestrian-involved collisions, while considering the typical vehicle ones as well. Methods: First, bivariate models are used to account for the common unobserved heterogeneity shared by the pedestrian- and vehicle-related crashes at the same intersections. Second, variable importance ranking technique is used, along with correlation analysis, to determine mode-specific feature input. Third, the exposure information for both modes, annual pedestrian count, and annual daily vehicles traveled are used for model development. Fourth, a recent Bayesian inference approach (integrated nested Laplace approximation (INLA)) was adopted for bivariate setting. Finally, different evaluation criteria are used to facilitate comprehensive model assessment. Results: The results reveal different statistically significant factors contributing to each of the modes. The offset intersection provides better safety performance for both pedestrians and drivers as compared to other intersection designs. The model findings also corroborate the sensibility of using the bivariate models, rather than the separate univariate ones. Practical Applications: The study shows that pedestrians are more vulnerable to various intersection features such as left-turn channelization, intersection control, urban and rural population group, presence of signal mastarm on the cross-street, and mainline average daily traffic. Greater focus should be directed toward such intersection features to improve pedestrian safety.     

The relationship between dewlap size and performance changes with age and sex in a Green Anole (Anolis carolinensis) lizard population

Ornaments are believed to signal an individual's ability to reproduce successfully and/or survive. Since an individual's fitness is often influenced by multiple traits (e.g. number of copulations, ability to acquire nest sites or to escape predators), which are difficult to quantify simultaneously, we examine performance traits (bite force, jumping performance) believed to be relevant to an individual's fitness. Specifically, we ask whether variation in dewlap size is related to variation in body size, bite force and jumping ability in the lizard Anolis carolinensis. Our results show that dewlap size is correlated with jumping capacity across all individuals, whereas the relationships between dewlap size, body size and bite force differ depending on sex/age class. We argue that selection against relatively large dewlaps at the transition between small mature and large mature males might be responsible for the lack of a relationship within large males. The absence or presence of a correlation between dewlap size and bite force, on the other hand, might be explained by differences in behaviour, such as territory establishment, anti-predator tactics, and/or mate choice. Our work thus suggests that selective forces influencing the evolution of ornaments may operate differently on different sexes and life-history stages.     

Uranium transport around the reactor zone at Bangombé and Okélobondo (Oklo): examples of hydrogeological and geochemical model integration and data evaluation

The sites at Bangombé and Okélobondo (Oklo) in Gabon provide a unique opportunity to study the behaviour of products from natural nuclear reactions in the vicinity of reactor zones which were active around two billion years ago. The Commission of the European Communities initiated the Oklo Natural Analogue Programme. One of the principal aims was to study indications of present time migration of elements from the reactor zones under ambient conditions. The hydrogeological and hydrochemical data from the Oklo sites were modelled in order to better understand the geochemical behaviour of radionuclides in the natural system, by using independent models and by comparing the modelling outcome. Two modelling approaches were used: M3 code (hydrochemical mixing and mass balance model), developed by the Swedish Nuclear Fuel and Waste Management Company (SKB) and HYTEC (reactive transport model) developed by Ecole des Mines de Paris.Two different reactor zones were studied: Bangombé, a shallow site, the reactor being at 11 m depth, and OK84 at Okélobondo, situated at about 450 m depth, more comparable with a real repository location. This allowed the validation of modelling tools in two different sedimentary environments: one shallow, with a more homogeneous layering situated in an area of meteoric alteration, and the other offering the opportunity to study radionuclide migration from the reaction zone over a distance of 450 m through very heterogeneous sedimentary layers.The modeling results indicate that the chemical reactions retarding radionuclide transport are very different at the two sites. At Bangombé, the decomposition of organic material consumes oxygen and at Okélobondo the oxygen is consumed by inorganic reactions resulting, in both cases, in uranium retardation. Both modelling approaches (statistic with M3 code and deterministic with HYTEC code) could describe this situation.The goal of this exercise is to test codes which can help to describe and understand the processes taking place at the sites, validate the models with in situ data, and thus build confidence in the tools used for future site characterization. Ultimately, this allows identifying and selecting processes and parameters that can be used as input into repository performance assessment calculations and modelling exercises.     

飞机风挡防(除)雾系统安全性能分析

飞机的风挡防（除）雾对飞行安全具有十分重要的意义。为此,重点研究飞机风挡内表面热气防（除）雾系统的性能,针对自由射流热空气防（除）雾系统,建立了其稳态安全性能评判模型,并以某型飞机风挡为例,在两种供气条件下,分析和计算了系统的结雾情况,根据综合分析得出结论