Moving towards urban sustainability in Kenya: a framework for integration of environmental,economic, social and governance dimensions

Global urban development is increasingly becoming an aspect of focus as nations fight sustainability challenges. A review of the current literature on urban sustainability suggests that research on development of cities, in both developed and developing countries, is growing fast, with an emphasis on sustainable development. However, very little of this research contains an integrated framework to systematically identify and examine the various dimensions of urban sustainability and to measure and evaluate them appropriately. Cities are more than the sum of their sectors, and are complex and interdependent systems on whose dynamics the quality of life of millions of human beings and a good part of the economy depend. Environmental, economic, social and governance problems can create formidable barriers to urban sustainability. Governance remains a critically important dimension of urban sustainability, especially when discussing urbanization in developing countries, given rapid population movements and imbalances in socio-economic development. Understanding how cities function is fundamental to resolving these imbalances. The aim of this paper is to provide a review and analysis of the concept of urban sustainability and to propose the development of a holistic framework through integration of environmental, economic, social, and governance dimensions of sustainability. Such a review would make it possible to understand the complex dynamics of the four dimensions and to assess the progress and challenges in moving towards urban sustainability, taking the case of Nairobi, Kenya, as an example. The paper argues that, for urban sustainability in developing countries, more emphasis should be placed on the governance dimension, because this is where the biggest challenge exists, with increasing needs for immediate management of rapid urbanization.     

Evaluations of combined zebrafish (Danio rerio) embryo and marine phytoplankton (Diacronema lutheri) toxicity of dissolved organic contaminants in the Ythan catchment,Scotland, UK

A wide variety of organic contaminants including pesticides, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) have previously been detected in surface waters in the river Ythan catchment, North East Scotland UK. While the concentrations detected were below Water Framework Directive Environmental Quality Standards (WFD-EQSs) environmental exposures to the diverse mixtures of contaminants, known and unknown, may pose chronic and/or sublethal effects to non target organisms. The present study assessed the embryo and algal toxicity potential of freely dissolved organic contaminants from the Ythan catchment using silicone rubber passive sampling devices (SR-PSDs) and miniaturised bioassay techniques. Zebrafish (Danio rerio) embryos and marine phytoplankton species (Diacronema lutheri) were exposed to extracts from SR-PSDs deployed at different locations along the river Ythan and an undeployed procedural blank. Statistically significant developmental and algal toxicities were measured in all tests of extracts from deployed samples compared with the procedural blanks. This indicates environmental exposure to, and the combined toxicity potential of, freely dissolved organic contaminants in the catchment. The present and previous studies in the Ythan catchment, coupling SR-PSDs and bioassay techniques, have both helped to understand the interactions and combined effects of dissolved organic contaminants in the catchment. They have further revealed the need for improvement in the techniques currently used to assess environmental impact.     

Inhibition equivalency factors for microcystin variants in recombinant and wild-type protein phosphatase 1 and 2A assays

In this work, protein phosphatase inhibition assays (PPIAs) have been used to evaluate the performance of recombinant PP1 and recombinant and wild-type PP2As. The enzymes have been compared using microcystins-LR (MC-LR) as a model cyanotoxin. Whereas PP2A_Rec provides a limit of detection (LOD) of 3.1 μg/L, PP1_Rec and PP2A_Wild provide LODs of 0.6 and 0.5 μg/L, respectively, lower than the guideline value proposed by the World Health Organization (1 μg/L). The inhibitory potencies of seven MC variants (-LR, -RR, -dmLR, -YR, -LY, -LW and -LF) have been evaluated, resulting on 50 % inhibition coefficient (IC₅₀) values ranging from 1.4 to 359.3 μg/L depending on the MC variant and the PP. The PPIAs have been applied to the determination of MC equivalent contents in a natural cyanobacterial bloom and an artificially contaminated sample, with multi-MC profiles. The inhibition equivalency factors (IEFs) have been applied to the individual MC quantifications determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, and the estimated MC-LR equivalent content has been compared to PPIA results. PPIAs have demonstrated to be applicable as MC screening tools for environmental applications and to protect human and animal health.     

Thermal Exploitation of Wastes with Lignite for Energy Production

Abstract

The thermal exploitation of wastewood with Greek lignite was investigated by performing tests in a laboratory-scale fluidized bed reactor, a 1-MW_th semi-industrial circulating fluidized bed combustor, and an industrial boiler.

Blends of natural wood, demolition wood, railroad sleepers, medium-density fiberboard residues, and power poles with lignite were used, and the co-combustion efficiency and the effect of wastewood addition on the emitted pollutants were investigated. Carbon monoxide, sulfur dioxide, and oxides of nitrogen emissions were continuously monitored, and, during the industrial-scale tests, the toxic emissions (polychlorinated dibenzodioxins and dibenzofurans and heavy metals) were determined. Ash samples were analyzed for heavy metals in an inductively coupled plasma-atomic emission spectroscopy spectrophotometer.

Problems were observed during the preparation of wastewood, because species embedded with different compounds, such as railway sleepers and demolition wood, were not easily treated. All wastewood blends were proven good fuels; co-combustion proceeded smoothly and homogeneous temperature and pressure profiles were obtained. Although some fluctuations were observed, low emissions of gaseous pollutants were obtained for all fuel blends. The metal element emissions (in the flue gases and the solid residues) were lower than the legislative limits. Therefore, wastewood co-combustion with lignite can be realized, provided that the fuel handling and preparation can be practically performed in large-scale installations.     

Analysis of Temporal and Spatial Dichotomous PM Air Samples in the El Paso-Cd. Juarez Air Quality Basin

ABSTRACT

This paper presents and discusses the results obtained from the gravimetric and chemical analyses of the 24-hr average dichotomous samples collected from five sites in the El Paso-Cd. Juarez air quality basin between August 1999 and March 2000. Gravimetric analysis was performed to determine the temporal and spatial variations of PM_2.5 (particulate matter less than 2.5 um in diameter) and PM2.5-10 (particulate matter less than 10 μm but greater than 2.5 μm in diameter) mass concentrations. The results indicate that ~25% of the PM10 (i.e., PM2.5 + PM2.5-10) concentration is composed of PM2.5. Concurrent measurements of hourly PM concentrations and wind speed showed strong diurnal patterns of the regional PM pollution. Results of X-ray fluorescence (XRF) elemental analyses were compared to similar but limited studies performed by the Texas Natural Resource Conservation Commission (TNRCC) in 1990 and 1997. Major elements from geologic sources—Al, Si, Ca, Na, K, Fe, and Ti—accounted for 35% of the total mass concentrations in the PM2.5-10 fraction, indicating that geologic sources in the area are the dominant PM sources. Levels of toxic trace elements, mainly considered as products of anthropogenic activities, have decreased significantly from those observed in 1990 and 1997.     

Development of functional composts using spent coffee grounds,poultry manure and biochar through microbial bioaugmentation

Spent coffee grounds (SCG), poultry manure, and agricultural waste-derived biochar were used to manufacture functional composts through microbial bioaugmentation. The highest yield of tomato stalk-based biochar (40.7%) was obtained at 450°C with a surface area of 2.35 m² g^?1. Four pilot-scale composting reactors were established to perform composting for 45 days. The ratios of NH₄⁺–N/NO₃^?–N, which served as an indicator of compost maturity, indicate rapid, and successful composting via microbial bioaugmentation and biochar amendment. Moreover, germination indices for radish also increased by 14–34% through augmentation and biochar amendment. Microbial diversity was also enhanced in the augmented and biochar-amended composts by 7.1–8.9%, where two species of Sphingobacteriaceae were dominant (29–43%). The scavenging activities of 2,2-diphenyl-1-picrylhydrazyl (DPPH) were enhanced by 14.1% and 8.6% in the fruits of pepper plants grown in the presence of the TR-2 (augmentation applied only) and TR-3 (both augmentation and biochar amendment applied) composts, respectively. Total phenolic content was also enhanced by 68% in the fruits of the crops grown in TR-3. Moreover, the other compost, TR-L (augmentation applied only), boosted DPPH scavenging activity by 111% in leeks compared with commercial organic fertilizer, while TR-3 increased the phenolic content by 44.8%. Composting facilitated by microbial augmentation and biochar amendment shortened the composting time and enhanced the quality of the functional compost. These results indicate that functional compost has great potential to compete with commercially available organic fertilizers and that the novel composting technology could significantly contribute to the eco-friendly recycling of organic wastes such as spent coffee grounds, poultry manure, and agricultural wastes.     

Inactivation of <Emphasis Type="Italic">Escherichia coli</Emphasis> in fresh water with advanced oxidation processes based on the combination of O<Subscript>3</Subscript>, H<Subscript>2</Subscript>O<Subscript>2</Subscript>, and TiO<Subscript>2</Subscript>. Kinetic modeling

The purpose of this work was to study the efficiency of different treatments, based on the combination of O₃, H₂O₂, and TiO₂, on fresh surface water samples fortified with wild strains of Escherichia coli. Moreover, an exhaustive assessment of the influence of the different agents involved in the treatment has been carried out by kinetic modeling of E. coli inactivation results. The treatments studied were (i) ozonation (O₃), (ii) the peroxone system (O₃/0.04 mM H₂O₂), (iii) catalytic ozonation (O₃/1 g/L TiO₂), and (iv) a combined treatment of O₃/1 g/L TiO₂/0.04 mM H₂O₂. It was observed that the peroxone system achieved the highest levels of inactivation of E. coli, around 6.80 log after 10 min of contact time. Catalytic ozonation also obtained high levels of inactivation in a short period of time, reaching 6.22 log in 10 min. Both treatments, the peroxone system (O₃/H₂O₂) and catalytic ozonation (O₃/TiO₂), produced a higher inactivation rate of E. coli than ozonation (4.97 log after 10 min). While the combination of ozone with hydrogen peroxide or titanium dioxide thus produces an increase in the inactivation yield of E. coli regarding ozonation, the O₃/TiO₂/H₂O₂ combination did not enhance the inactivation results. The fitting of experimental values to the corresponding equations through non-linear regression techniques was carried out with Microsoft® Excel GInaFiT software. The inactivation results of E. coli did not respond to linear functions, and it was necessary to use mathematical models able to describe certain deviations in the bacterial inactivation processes. In this case, the inactivation results fit with mathematical models based on the hypothesis that the bacteria population is divided into two different subgroups with different degrees of resistance to treatments, for instance biphasic and biphasic with shoulder models.

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Behavioural determinants of gene flow in the bat Miniopterus schreibersii

Dispersal and migratory behaviours are often important determinants of gene flow in wild species, and we have studied their role using ringing-recapture data in the Portuguese population of Miniopterus schreibersii, a cave-dwelling bat that forms large maternity colonies. Juvenile dispersal, usually a major agent of gene flow, appears to be negligible, as young females never settled to give birth in foreign colonies. Likewise, there was virtually no dispersal of adult females to foreign maternity colonies. This strong philopatry virtually eliminated female-mediated gene flow, but we found a great potential for male-mediated gene flow among colonies, as regional migrations temporarily joined both sexes from different colonies in the same roosts, during the mating season. In fact, females from some colonies were more likely to mate with males from foreign colonies than from their own, thus potentially bringing home genes of foreign males. In spite of this abundant gene flow, we found a pattern of isolation by distance and even strong barriers to gene flow, which is explained by the fact that migrations were usually too short to allow direct flow among distant colonies. We concluded that potential gene flow is influenced by the distance between colonies and the availability of mating roosts between them. In addition, we found this flow to be asymmetrical, with a dominant direction from the largest to the smallest colonies. Our ringing-recapture estimates of potential gene flow based on dispersal and migratory behaviour are compatible with the genetic structure of the population for both nuclear and mitochondrial DNA. Our conclusions have implications for the conservation of bats with a spatial behaviour similar to that of M. schreibersii. Colonies should be managed individually because strict female philopatry not only promotes their isolation but also minimises the contribution of immigration in rescuing declining colonies. Furthermore, the results underline the importance of preserving mating roosts to maintain gene flow among colonies.     

Decay effects of pollutants on stony materials in the built environment

This review discuss the effects that pollutants have on stony materials applied on the built environment, illustrating different macroscopical products (pathologies) that can affect historical and modern architectural works. The impact of the decay processes is related to the susceptibility of the materials, environmental conditions and the kind of pollutants that degrade building materials. Here are reviewed the main decay processes resulting from the actions of gases, particulate matter and solutions (from wet deposition to capillary rising and including circulating waters such as run-off), showing that besides atmospheric pollution, also pollutants rising from the ground can cause important deterioration on building materials. Following, the use of tracers is considered for the study of pollutant sources and migration, including neoformation minerals (that might also constitute markers of environmental conditions) and chemical tracers, giving special attention to isotopic tracers, namely to proposals regarding the use of some stable and radioactive isotopes for the study of pollutants that have strong potential but have not been tested yet are also presented. At the end of this chapter, some final considerations are made on the problem of durability assessment of materials in the built environment and also on the use of tracers to assess the origin of damaging compounds in the built environment.     

Social competition masculinizes the communication signals of female electric fish

Male intrasexual competition and female choice explain the evolution of male ornaments. Except in sex-role-reversed taxa, female ornaments have been regarded as an epiphenomenon of genetic correlation, with no female-specific function or independently selected basis. Females from species with conventional sex roles may still experience some degree of female–female competition and male choice that could explain the persistence of female ornaments. We studied the effect of female competition on the expression of a sexually dimorphic communication signal. In the electric fish Brachyhypopomus gauderio, both sexes produce an electric signal pulse for communication and electrolocation. Male electric pulses are longer in duration and greater in amplitude than those of females. As competition increases, males further enhance their signals in response to elevated androgen levels. We explored whether females respond to social competition as males do, by enhancing their communication signals and increasing androgen levels. We measured amplitude and duration of the electric signal pulse, and testosterone levels in female B. gauderio in their natural habitat in Uruguay and estimated social competition by calculating population density and adult sex ratio (ASR). In the lab, we manipulated ASR and population density independently to separate these factors and eliminate seasonal confounds. Under both field and lab conditions, signal pulse amplitude increased with population density, while pulse duration increased with female bias in ASR. In the field, but not the lab, androgen levels increased when ASR was female biased. Our findings indicate that the socially mediated mechanism of signal regulation is shared by the sexes, although whether androgens regulate this signal plasticity in females remains unclear.