Wilk’s Method Based Model for Regulations Related to Radiological Impact of Opencast Uranium Mining on Water Reservoirs

Opencast mining of uranium may lead to natural erosion of ore material due to overland flow of water accumulated from rainfall. The overland flow may ultimately reach the nearby surface water body. This process may lead to the release of ²³⁸U and its daughter products into the surface water body. A model is developed to assess the radiological impact of the erosion in terms of dose through drinking water pathway due to ²³⁸U and its progeny in the surface water body. The in-growth of progeny is taken into account using Bateman equations. The study brings out the importance of incorporating decay chain transport in the radiological impact assessment studies. It is also observed that ²¹⁰Po, ²¹⁰Pb, ²²⁶Ra, and ²³⁰Th together contribute to about 95.5 % of the total dose. The model is then extended to incorporate the uncertainty associated with the dose due to consumption of the reservoir water by employing Wilk’s Method. Such a model can be very useful in establishing regulations related to dose through drinking water pathway around an opencast mine. Wilk’s method is computationally less expensive as compared to the exact methods like Monte Carlo method. Wilk’s method is used to calculate a value greater than α percentile value for the dose to the public due to ²³⁸U and its progeny in the reservoir through drinking water pathway with confidence level β (α/β value). When applied to a hypothetical case using some literature data on surface water bodies, it is found that with increase in the value of α or β, the α/β value in general, shows an increasing trend as expected. Depending upon the nature of the problem under study, one can calculate an α/β value i.e. 95/95 value, 99/95 value etc., and that value can be helpful in establishing the regulatory limiting value. Also, the α/β value can be used to check whether dose due to a particular radioactive release is within the specified limits.     

Movement ecology: size-specific behavioral response of an invasive snail to food availability

Immigration, emigration, migration, and redistribution describe processes that involve movement of individuals. These movements are an essential part of contemporary ecological models, and understanding how movement is affected by biotic and abiotic factors is important for effectively modeling ecological processes that depend on movement. We asked how phenotypic heterogeneity (body size) and environmental heterogeneity (food resource level) affect the movement behavior of an aquatic snail (Tarebia granifera), and whether including these phenotypic and environmental effects improves advection-diffusion models of movement. We postulated various elaborations of the basic advection diffusion model as a priori working hypotheses. To test our hypotheses we measured individual snail movements in experimental streams at high- and low-food resource treatments. Using these experimental movement data, we examined the dependency of model selection on resource level and body size using Akaike's Information Criterion (AIC). At low resources, large individuals moved faster than small individuals, producing a platykurtic movement distribution; including size dependency in the model improved model performance. In stark contrast, at high resources, individuals moved upstream together as a wave, and body size differences largely disappeared. The model selection exercise indicated that population heterogeneity is best described by the advection component of movement for this species, because the top-ranked model included size dependency in advection, but not diffusion. Also, all probable models included resource dependency. Thus population and environmental heterogeneities both influence individual movement behaviors and the population-level distribution kernels, and their interaction may drive variation in movement behaviors in terms of both advection rates and diffusion rates. A behaviorally informed modeling framework will integrate the sentient response of individuals in terms of movement and enhance our ability to accurately model ecological processes that depend on animal movement.     

Source Apportionment and Identification of Polycyclic Aromatic Hydrocarbons (PAHs) in Sediment Cores of Selected Creeks in Delta State,Nigeria

Polycyclic aromatic hydrocarbons (PAHs) seasonal variation and sources in Ubeji, Ifie, and Egbokodo Creeks of the Niger Delta, Nigeria, were predicted using diagnostic ratios (DRs) of parent PAHs (Phe/Phe + Ant; Flu/Flu + Pyr; BaA/BaA + Chry, and Ind/Ind + BghiP) and principal component analysis (PCA). A total of 222 sediment core samples were collected during the wet (August 2010) and the dry seasons (January 2011). The samples were dried and Soxhlet extracted; sample extracts were fractionated and analyzed by gas chromatography/flame ionization detection (GC/FID) to identify individual PAHs. The diagnostic PAH ratios revealed that PAHs in the sediment cores at the three creeks, in both seasons, mainly stemmed from the combustion process (pyrogenic sources). Principal component analysis further confirmed that wood-burning, coal combustion, diesel, gasoline-powered vehicular emissions, and petroleum combustion were the dominant contributors of PAHs sources at the sampling location. This study provided information on the origin and sources of PAHs in sediment cores, which may be useful for regulatory actions, environmental quality management, contamination history, and environmental forensic studies.     

Inverse Modeling for Aquatic Source and Transport Parameters Identification and its Application to Fukushima Nuclear Accident

Inverse modeling technique based on nonlinear least square regression method (LSRM) is developed for the identification of aquatic source and transport parameters. Instantaneous line source release model in two-dimensional domain and continuous point source release model in three-dimensional domain are used for the purpose. Case studies have been carried out for both types of releases to illustrate their application. Error analysis has been carried out to identify the maximum error that can be tolerated in the input concentration data used in the inverse model and to specify the minimum number of sampling points to generate such input data. The LSRM is compared with the well-established correlation coefficient optimization method for instantaneous line source release model, and good comparison is observed between them. The LSRM is used to quantitatively estimate the releases of different radionuclides into the Pacific Ocean which has resulted due to the discharge of highly radioactive liquid effluent from the affected Daiichi Nuclear Power Station at Fukushima in Japan. The measured concentrations of these radionuclides in seawater samples collected from two sampling points near Fukushima are used for the estimation. The average release works out to be 1.09?×?10¹⁶ for ¹³¹I, 3.4?×?10¹⁵ Bq for ¹³⁴Cs, and 3.57?×?10¹⁵ Bq for ¹³⁷Cs. Very good agreement is observed between the releases estimated in this study and those estimated by other different agencies.     

Human health effects of residual carbon nanotubes and traditional water treatment chemicals in drinking water

The volume of industrial and domestic wastewater is increasing significantly year by year with the change in the lifestyle based on mass consumption and mass disposal brought about by the dramatic development of economies and industries. Therefore, effective advanced wastewater treatment is required because wastewater contains a variety of constituents such as particles, organic materials, and emulsion depending on the resource. However, residual chemicals that remain during the treatment of wastewaters form a variety of known and unknown by-products through reactions between the chemicals and some pollutants. Chronic exposure to these by-products or residual chemicals through the ingestion of drinking water, inhalation and dermal contact during regular indoor activities (e.g., showering, bathing, cooking) may pose cancer and non-cancer risks to human health. For example, residual aluminium salts in treated water may cause Alzheimer's disease (AD). As for carbon nanotubes (CNTs), despite their potential impacts on human health and the environment having been receiving more and more attention in the recent past, existing information on the toxicity of CNTs in drinking water is limited with many open questions. Furthermore, though general topics on the human health impacts of traditional water treatment chemicals have been studied, no comparative analysis has been done. Therefore, a qualitative comparison of the human health effects of both residual CNTs and traditional water treatment chemicals is given in this paper. In addition, it is also important to cover and compare the human health effects of CNTs to those of traditional water treatment chemicals together in one review because they are both used for water treatment and purification.     

Dissecting the drivers of population cycles: Interactions between parasites and mountain hare demography

There is a growing awareness that cyclic population dynamics in vertebrate species are driven by a complex set of interactions rather than a single causal factor. While theory suggests that direct host-parasite interactions may destabilise population dynamics, the interaction between host and parasite may also influence population dynamics through indirect effects that result in delayed responses to either density or to life-history traits. Using empirical data on mountain hares (Lepus timidus) infected with a nematode parasite (Trichostrongylus retortaeformis), we developed an individual-based model (IBM) that incorporated direct effects and delayed life-history effects (DLHEs) of a macroparasite, alternative transmission mechanisms and seasonality in host population dynamics. The full model describes mean characteristics of observed mountain hare time series and parasite abundance, but by systematically removing model structure we dissect out dynamic influences of DLHEs. The DLHEs were weakly destabilising, increasing the propensity for cyclic dynamics and suggesting DLHEs could be important processes in host-parasite systems. Further, by modifying model structure we identify a strong influence of parasite transmission mechanism on host population stability, and discuss the implications for parasite aggregation mechanisms, host movement and natural geographical variation in host population dynamics. The effect of T. retortaeformis on mountain hares likely forms part of a complex set of interactions that lead to population cycles.     

Environment security: an empirical study of industrialization and the impact on environment in the Dhaka division, Bangladesh

Dhaka division is the main central industrial zone in Bangladesh. Along with the great growth in industry in the region, there have also been increased and sometimes critical levels of toxic pollution to the environment. Although much has been researched in the region on the degradation of the environment, the slow improvements in environment protection drive the question of what is the environmental security climate in Dhaka division. The study of four plants (textile, leather tanning, cement and fertilizer) in Dhaka division aimed to find out the impact of each on the environment. The study took place within Tejgaon, Hazaribagh, Narsingdi and Narayangang and investigated the impact of those plants on air, water and land. Among the different polluters, the results indicated that textiles polluted most. All participants indicated that the industries were the cause of at least one ailment within 6?months. It is recommended to governments and plant owners that they not only remain diligent about policy on environment protection, but that they also humanize efforts so as to follow those policies through to the end. The loss of life and quality of life may have larger impacts that daily profitability and livelihood.     

Influences, practices and opportunities for environmental supply chain management in Nova Scotia SMEs

Executives are increasingly paying attention to the importance of supply chain management [Lambert DM, Cooper MC. Issues in supply chain management. Industrial Marketing Management 2000;29(1):65–83; Hagelaar GJLF, van der Vorst JGAJ. Environmental supply chain management: using life cycle assessment to structure supply chains. International Food and Agribusiness Management Review 2002;4:399–412]. The management of the supply chain can be a central aspect of a company's competitive advantage [Preuss L. Rhetoric and reality of corporate greening: a view from the supply chain management function. Business Strategy and the Environment 2005;14:123–139]. SCM also offers considerable opportunities to reduce a company's environmental impact. The supply chains of three small and medium enterprises (SMEs) operating in the Burnside Industrial Park in Nova Scotia, Canada were investigated to explore the opportunities to improve environmental performance of SMEs linked in supply chains. This study confirmed that time and, to a lesser degree, financial resources to address solid waste and energy issues are the greatest limiting factors. Small suppliers, and even to a certain degree medium-sized enterprises, have difficulties in allocating resources to initiatives that are not viewed as directly related to their core function, namely manufacturing the product or providing the service. This study clearly demonstrated that opportunities exist to reduce greenhouse gas emissions and solid waste. Although, the benefits that would be gained from the implementation of any of the individual actions in the supply chains explored in this study are individually small, the cumulative benefits that could be achieved among supply chains and within industrial parks are substantial, given the number of small- and medium-sized enterprises.