Biosorption of zinc ions from aqueous solution by the microalga Scenedesmus obliquus

Aquatic environments are often exposed to toxic heavy metals, which gain access to the food chain via microalgae and may cause severe problems at higher trophic levels. However, such a metabolic specificity can be taken advantage of in bioremediation strategies. The potential of a novel wild strain of Scenedesmus obliquus, previously isolated from a heavy metal-contaminated site in northern Portugal, to remove Zn from aqueous solutions was thus studied, using several initial concentrations. The removal extent reached its maximum by 1 day: 836.5 mg Zn/g biomass, at the initial concentration of 75 mg/L, mainly by adsorption onto the cell surface. Comparative studies encompassing a commercially available strain of the same microalgal species led to a maximum removal extent of only 429.6 mg Zn/g biomass, under identical conditions. Heat-inactivated cells permitted a maximum removal of 209.6 mg Zn/g biomass, at an initial concentration of 50 mg Zn/L. The maximum adsorption capacity of Zn, estimated via Langmuir’s isotherm, was 330 mg Zn/g biomass. Finally, Zn removal was highest at pH 6.0–7.0. It was proven, for the first time, that such a wild microalga can uptake and adsorb Zn very efficiently, which unfolds a particularly good potential for bioremediation. Its performance is far better than similar (reference) species, especially near neutrality, and even following heat-treatment.     

Paradigms for parasite conservation

Parasitic species, which depend directly on host species for their survival, represent a major regulatory force in ecosystems and a significant component of Earth's biodiversity. Yet the negative impacts of parasites observed at the host level have motivated a conservation paradigm of eradication, moving us farther from attainment of taxonomically unbiased conservation goals. Despite a growing body of literature highlighting the importance of parasite‐inclusive conservation, most parasite species remain understudied, underfunded, and underappreciated. We argue the protection of parasitic biodiversity requires a paradigm shift in the perception and valuation of their role as consumer species, similar to that of apex predators in the mid‐20th century. Beyond recognizing parasites as vital trophic regulators, existing tools available to conservation practitioners should explicitly account for the unique threats facing dependent species. We built upon concepts from epidemiology and economics (e.g., host‐density threshold and cost‐benefit analysis) to devise novel metrics of margin of error and minimum investment for parasite conservation. We define margin of error as the risk of accidental host extinction from misestimating equilibrium population sizes and predicted oscillations, while minimum investment represents the cost associated with conserving the additional hosts required to maintain viable parasite populations. This framework will aid in the identification of readily conserved parasites that present minimal health risks. To establish parasite conservation, we propose an extension of population viability analysis for host–parasite assemblages to assess extinction risk. In the direst cases, ex situ breeding programs for parasites should be evaluated to maximize success without undermining host protection. Though parasitic species pose a considerable conservation challenge, adaptations to conservation tools will help protect parasite biodiversity in the face of an uncertain environmental future.     

Quantitative microbial risk assessment (QMRA) for setting health-based performance targets during soil aquifer treatment

Environmental Science and Pollution Research - A quantitative microbial risk assessment was conducted to assess the health risks associated with the exposure of agricultural workers to tertiary...     

Use of co-combustion bottom ash to design an acoustic absorbing material for highway noise barriers

The present study aims to determine and evaluate the applicability of a new product consisting of coal bottom ash mixed with Portland cement in the application of highway noise barriers. In order to effectively recycle the bottom ash, the influence of the grain particle size of bottom ash, the thickness of the panel and the combination of different layers with various particle sizes have been studied, as well as some environmental properties including leachability (EN-12457-4, NEN-7345) and radioactivity tests. Based on the obtained results, the acoustic properties of the final composite material were similar or even better than those found in porous concrete used for the same application. According to this study, the material produced presented no environmental risk.     

Inexact fuzzy-stochastic constraint-softened programming – A case study for waste management

In this study, an inexact fuzzy-stochastic constraint-softened programming method is developed for municipal solid waste (MSW) management under uncertainty. The developed method can deal with multiple uncertainties presented in terms of fuzzy sets, interval values and random variables. Moreover, a number of violation levels for the system constraints are allowed. This is realized through introduction of violation variables to soften system constraints, such that the model’s decision space can be expanded under demanding conditions. This can help generate a range of decision alternatives under various conditions, allowing in-depth analyses of tradeoffs among economic objective, satisfaction degree, and constraint-violation risk. The developed method is applied to a case study of planning a MSW management system. The uncertain and dynamic information can be incorporated within a multi-layer scenario tree; revised decisions are permitted in each time period based on the realized values of uncertain events. Solutions associated with different satisfaction degree levels have been generated, corresponding to different constraint-violation risks. They are useful for supporting decisions of waste flow allocation and system-capacity expansion within a multistage context.     

Municipal solid waste management: Identification and analysis of engineering indexes representing demand and costs generated in virtuous Italian communities

The definition and utilisation of engineering indexes in the field of Municipal Solid Waste Management (MSWM) is an issue of interest for technicians and scientists, which is widely discussed in literature. Specifically, the availability of consolidated engineering indexes is useful when new waste collection services are designed, along with when their performance is evaluated after a warm-up period. However, most published works in the field of MSWM complete their study with an analysis of isolated case studies. Conversely, decision makers require tools for information collection and exchange in order to trace the trends of these engineering indexes in large experiments. In this paper, common engineering indexes are presented and their values analysed in virtuous Italian communities, with the aim of contributing to the creation of a useful database whose data could be used during experiments, by indicating examples of MSWM demand profiles and the costs required to manage them.     

Planning and design of Berg-en-Dal,a new camp in Kruger National Park

The premise of this article is that the planning and design of new rest camps in conservation areas should be based on ecological principles in such a way that the plant ecology within the camp be an integral part and extension of the natural ecology of its immediate vicinity. This is desirable so that visitors to the camp will be provided not only with facilities for resting, eating, and sleeping, but also be able to enjoy and study the natural environment in a relaxed atmosphere. The Berg-en-Dal rest camp, which was established in Kruger National Park, was planned in such a way and designed according to the principles outlined by the authors in a companion article. The planning included six zones: a control zone, day visitor zone, overnight visitor zone, staff accommodation zone, recreation zone, and service zone. The point is stressed that plant species selected to be used as additional vegetation to those already growing in the camp were endemic to the nine landscape facets identified in the camp. The design allowed for separation of the various land-use zones in such a way that they would complement each other rather than be a hindrance to each other. The camp has been built according to the plans included in this article and has proved to be a great success. The conclusion is drawn that the planning principles are sound and should be used in the future for the planning and design of rest camps for conservation areas in South Africa.     

ESTIMATED RUNOFF FROM MAN-MADE SNOW1

ABSTRACT: The consumptive loss from man-made snowmaking at six Colorado ski areas is calculated. The focus of the procedures in this investigation is on the consumptive loss that occurs to man-made snow particles during the period they reside on or in the snowpack until spring snowmelt (termed the watershed loss). Calculated watershed losses under a variety of precipitation and temperature conditions at six ski areas varied from 7 to 33 percent. These calculations were made using the calibrated Subalpine Water Balance Simulation Model (Leaf and Brink, 1973a, 1973b). The watershed loss of 7 to 33 percent indicates the range of likely watershed losses that can be expected at Colorado ski areas. A previous paper by the authors (Eisel et al., 1988) provided estimates of the mean consumptive loss during the snowmaking process (termed initial loss) for conditions existing at Colorado ski areas to be 6 percent of water applied. Therefore, based on the mean initial loss, the total consumptive loss from man-made snowmaking under conditions found at Colorado ski areas could be expected to range from 13 to 37 percent. These results demonstrate the range of total consumptive losses that could be expected in various years and for various watershed conditions. These total percentage losses cannot be extrapolated directly to other specific sites because the total consumptive loss is dependent on temperature during actual snowmaking, temperature and precipitation throughout the winter at the specific ski area, and watershed conditions at the ski area. Consumptive losses to man-made snow for a specific ski area should be estimated using the handbook procedures developed especially for this purpose (Colorado Ski Country USA, 1986b).     

The use of silver as a selective precipitant for I in radioactive waste management

¹²⁹I is one of the more hazardous nuclides occurring in radioactive waste. In the form of I⁻, its most likely speciation, it is poorly sorbed on most geologic media. Several workers have suggested the use of silver to precipitate I⁻ as the insoluble AgI, in a cemented waste form, or as a “getter”. The efficacy of this procedure is examined by experiment, in conjunction with thermodynamic predictions.The addition of AgNO₃ to Portland cement leads to coprecipitation with C-S-H, with low Ag solubilities ( 10 μmg/L); 2–;3 orders of magnitude lower than predicted (from Ag₂O). AgI is stable in these matrices, with low aqueous I concentrations (<2 mg/L). In 85% BFS-15% OPC pastes, AgI is unstable due to redox and complexation reactions, with much I⁻ passing into solution; concentrations up to 900 mg/L were observed. It is shown that repository conditions, on closure, are also likely to induce solubilisation of I⁻ from AgI. It is concluded that the use of Ag is unlikely to significantly improve the immobilisation properties of the near field for radioiodine.     

Air borne particulate distributions and their accumulation in tree canopies,Nottingham, UK

Summary The deposition of particulates emanating from the south of Nottingham, UK, where the coal-fired power station of Ratcliffe- on-Soar is an important industry was assessed using snow samples, dry deposition gauges, and precipitation gauges.Effects of leaf characteristics in terms of shape, surface area, presentation, and cuticular texture on particulate accumulation were examined. Leaves possessing a large surface area, rough cuticular surface and with a horizontal presentation, were particularly effective in the accumulation of particulates. The penetration of particulates through the foliar canopy is discussed.The senior author is Section Leader and Principal Lecturer in Ecology in the Department of Life Sciences at Trent Polytechnic.