Fractionation and ecotoxicological implication of potentially toxic metals in sediments of three urban rivers and the Lagos Lagoon,Nigeria, West Africa

The potential environmental impact of sediment-bound Cd, Cr, Cu, Pb and Zn in three trans-urban rivers in Lagos state and in the Lagos Lagoon was assessed by use of the modified Community Bureau of Reference (BCR) sequential extraction. The quality of the data was checked using BCR CRM 143R and BCR CRM 701. Good agreement was obtained between found and certified/indicative values. Of the rivers, the Odo-Iyaalaro, was generally the most contaminated and the Ibeshe the least. Higher concentrations of metals were generally found in the dry season compared to the wet season. Cadmium and Zn were released mostly in the acid exchangeable step of the sequential extraction, indicating that they have the greatest potential mobility and bioavailability of the analytes studied. Chromium and Cu were associated mainly with the reducible and oxidisable fractions, and Pb predominantly with the reducible and residual fractions. Sediments with the highest pseudototal analyte concentrations also released higher proportions of analytes earlier in the sequential extraction procedure. The study suggests that, during the dry season, potentially toxic metals (PTM) may accumulate in sediments in relatively labile forms that are released and can potentially be transported or bioaccumulate in the rainy season. Application of risk assessment codes and Hankanson potential risk indices indicated that Cd was the element of greatest concern in the Lagos Lagoon system. The study indicated that there is a need to strengthen environmental management and pollution control measures to reduce risk from PTM, but that even relatively simple strategies, such as seasonal restrictions on dredging and fishing, could be beneficial.     

Development and testing a diagnostic capacity tool for improving socio-ecological system governance

The capacity to sustainably govern complex socio-ecological systems (SES) has been identified as a necessary but daunting task by SES scholars, resource stewards and stakeholders. This research sought to inform the question: What are determinant capacities and functional linkages that can be incorporated into diagnostic tools for analysts seeking to improve sustainable socio-economic system SES governance? Literature was used to identify and translate determinant capacities and functional linkages into a quantifiable metric of governance quality. The tool was developed from ecological, business, governance and decision science literature. This tool recognizes the dynamic and systemic linkages between the resources and the social systems that use and govern them for improving systems thinking and SES outcomes. The tool was tested to determine its ability to capture perceived characteristics of governance quality and problem management using Michigan’s cleanup and redevelopment program. The results of this research indicated that the exploratory tool was reliable and valid. This research contributes to the evolving body of SES frameworks, specifically the study of individual and organizational capacities for improved SES outcomes. The implications of this research suggest participatory network-based governance with higher levels of resource exchange, in the form of interdependency, trust, diplomacy and reciprocity, aligns with practitioners’ perceptions of improved program performance. Further, while some capacities and related findings of this research may be context specific, concepts associated with the development and testing of this diagnostic tool, such as the use of systems thinking, participatory network-based governance, and related competencies, may have more universal application.     

Bioretention Design for Xeric Climates Based on Ecological Principles1

Abstract: Bioretention as sustainable urban stormwater management has gathered much recent attention, and implementation is expanding in mesic locations that receive more than 1,000 mm of annual precipitation. The arid southwestern United States is the fastest growing and most urbanized region in the country. Consequently, there is a need to establish design recommendations for bioretention to control stormwater from expanding urban development in this ecologically sensitive region. Therefore, we review the ecological limits and opportunities for designing bioretention in arid and semiarid regions. We incorporated USEPA Stormwater Management Model (SWMM) simulations to synthesize ecologically based design recommendations for bioretention in arid climates. From our review, an ideal bioretention garden area should be 6 to 8% of the contributing impervious drainage area (depending on region) with two layers of media, a 0.5‐m low‐nutrient topsoil layer above a 0.6‐m porous media layer that acts as temporary storage during a storm event. When planted with the suggested vegetation, this design maximizes stormwater treatment by promoting ecological treatment in the topsoil while promoting infiltration and evapotranspiration of stormwater by deep‐rooted shrubs that require no irrigation after establishment. This synthesis improves water resources management in arid and semiarid regions by introducing a sustainable bioretention design that protects local surface waters while reducing regional water demands for irrigation.     

Fate and effects of metal-based nanoparticles in two marine invertebrates,the bivalve mollusc Scrobicularia plana and the annelid polychaete Hediste diversicolor

The objective of this paper is to synthesize results from seven published research papers employing different experimental approaches to evaluate the fate of metal-based nanoparticles (Ag NPs, Au NPs, CuO NPs, CdS NPs, ZnO NPs) in the marine environment and their effects on two marine endobenthic species, the bivalve Scrobicularia plana and the ragworm Hediste diversicolor. The experiments were carried out under laboratory (microcosms) conditions or under environmentally realistic conditions in outdoor mesocosms. Based on results from these seven papers, we addressed the following research questions: (1) How did the environment into which nanoparticles were released affect their physicochemical properties?, (2) How did the route of exposure (seawater, food, sediment) influence bioaccumulation and effects?, (3) Which biomarkers were the most responsive? and (4) Which tools were the most efficient to evaluate the fate and effects of NPs in the marine environment? The obtained results showed that metal‐based NPs in general were highly agglomerated/aggregated in seawater. DGT tools could be used to estimate the bioavailability of metals released from NPs under soluble form in the aquatic environment. Both metal forms (nanoparticulate, soluble) were generally bioaccumulated in both species. Among biochemical tools, GST and CAT were the most sensitive revealing the enhancement of anti-oxidant defenses in both species exposed to sub-lethal concentrations of metal-based NPs. Apoptosis and genotoxicity were frequently observed.     

A probabilistic model for the carry-over of PCDD/Fs from feed to growing pigs

When food producing animals are contaminated with PCDD/F congeners, information on the contaminant’s concentration in the bodies of the animals at time of slaughter is needed for risk management purposes. We have developed a mathematical model for the kinetics of PCDD/Fs in growing pigs in case of contaminated feed fed for a limited duration of time. This model allows the prediction of concentrations in body fat. It considers absorption fractions of PCDD/Fs, clearance by metabolism, dilution by growth and excretion through fecal fat. The model parameters were calibrated by fitting the model to experimental data. On the basis of this toxicokinetic model a probabilistic model has been constructed. The probabilistic model handles the parameters with appropriate probability distributions and Monte-Carlo simulation technique, providing for realistic situations with many animals and a range of contaminations and feeding intervals. We applied the new model to describe the German dioxin incident of winter 2010/2011 and discuss its viability as decision tool. The approach demonstrated here is a showcase how a risk assessment in the case of contaminated feeding can be performed.     

Rheological Studies of Microfibrillar Cellulose Water Dispersions

The rheological behaviour of microfibrillar cellulose (MFC) water dispersions has been investigated. For the first time a detailed study of shear dependent viscosity at low and high shear rate is presented. A peculiar time dependent behaviour measured in the area between 0 and 1000 s⁻¹ was identified. The study shows a hysteresis loop in the shear rate–viscosity relationship at low shear rate. Additional time dependent shear rate measurements were performed, and a hypothesis for a mechanism of interaction and formation of a fibrils network was suggested. Higher temperature caused lower viscosity values, and this difference was increased at higher shear rate values. Oscillatory measurements showed how the closeness of the fibrils helps network creations. Data obtained from high shear measurements showed that 1% MFC water dispersions had a dilatant behaviour at ultra high shear rates with values increasing from 120 to 300 Pa s in the area between 180,000 and 330,000 s⁻¹ .     

Identifying the antecedents of coping with an organizational acquisition: a structural assessment

This study used Lazarus and Folkman's ( 1984 ) cognitive–phenomenological model of coping and Lazarus's ( 1991 ) theory of emotions to develop and test a model of how individuals cope with an organizational acquisition. The model identifies the origins and process used to select both problem‐focused and emotion‐focused coping strategies. Covariance structure analysis of data from 172 individuals indicated that problem‐focused coping was directly influenced by primary appraisal and negative emotion, while only certain types of emotion‐focused coping were directly related to negative emotion. All coping strategies were impacted by social support. Furthermore, negative emotion was predicted by primary appraisal, which in turn was related to perceived control, coping efficacy, and environmental conditions. Recommendations for future research and applications are discussed. Copyright © 2000 John Wiley & Sons, Ltd.     

Communication with police supervisors and peers as a buffer of work‐related traumatic stress

Traumatic events are a particular type of stressor that may affect police officers engaged in front line duties. In this study, specific types of social support predicted to buffer the psychological and physical health effects of trauma are drawn from theory and empirical evidence in the area of post‐traumatic stress. Social support, measured as the content of communication, and the ease of talking about trauma was tested with 527 working police officers who responded to a questionnaire survey. Hierarchical regression analysis showed that the communication variables contributed to the variance in post‐traumatic stress disorder and physical symptoms with differential effects for different aspects of communication. Analysis of the effects of traumatic stress on symptoms for sub‐groups at different levels of communication showed that some types of communication, such as the ease of talking about trauma or positive communications about work, moderate the effects of stress for police officers, in that higher levels are associated with a weaker trauma–strain relationship. However, some types of communication buffered stress only at moderate levels and other types may not be protective. These results are discussed in terms of the types and sources of social support that are likely to buffer post‐traumatic stress at work. Copyright © 2000 John Wiley & Sons, Ltd.     

Mainstreaming climate adaptation: taking stock about “what works” from empirical research worldwide

Adaptation to a changing climate is unavoidable. Mainstreaming climate adaptation objectives into existing policies, as opposed to developing dedicated adaptation policy, is widely advocated for public action. However, knowledge on what makes mainstreaming effective is scarce and fragmented. Against this background, this paper takes stock of peer-reviewed empirical analyses of climate adaptation mainstreaming, in order to assess current achievements and identify the critical factors that render mainstreaming effective. The results show that although in most cases adaptation policy outputs are identified, only in a minority of cases this translates into policy outcomes. This “implementation gap” is most strongly seen in developing countries. However, when it comes to the effectiveness of outcomes, we found no difference across countries. We conclude that more explicit definitions and unified frameworks for adaptation mainstreaming research are required to allow for future research syntheses and well-informed policy recommendations.

     

A framework of connections between soil and people can help improve sustainability of the food system and soil functions

Globally soil quality and food security continue to decrease indicating that agriculture and the food system need to adapt. Improving connection to the soil by knowledge exchange can help achieve this. We propose a framework of three types of connections that allow the targeting of appropriate messages to different groups of people. Direct connection by, for example, handling soil develops soil awareness for management that can be fostered by farmers joining groups on soil-focused farming such as organic farming or no-till. Indirect connections between soil, food and ecosystem services can inform food choices and environmental awareness in the public and can be promoted by, for example, gardening, education and art. Temporal connection revealed from past usage of soil helps to bring awareness to policy workers of the need for the long-term preservation of soil quality for environmental conservation. The understanding of indirect and temporal connections can be helped by comparing them with the operations of the networks of soil organisms and porosity that sustain soil fertility and soil functions.