Nickel ferrite nanoenabled graphene oxide (NiFe2O4@GO) as photoactive nanocomposites for water treatment

Environmental Science and Pollution Research - Nanocomposite materials can enhance the capabilities of water treatment processes such as photocatalysis. In this work, novel light-driven...     

Anaerobic digestion of microalgal biomass after ultrasound pretreatment

High rate algal ponds are an economic and sustainable alternative for wastewater treatment, where microalgae and bacteria grow in symbiosis removing organic matter and nutrients. Microalgal biomass produced in these systems can be valorised through anaerobic digestion. However, microalgae anaerobic biodegradability is limited by the complex cell wall structure and therefore a pretreatment step may be required to improve the methane yield. In this study, ultrasound pretreatment at a range of applied specific energy (16–67 MJ/kg TS) was investigated prior to microalgae anaerobic digestion. Experiments showed how organic matter solubilisation (16–100%), hydrolysis rate (25–56%) and methane yield (6–33%) were improved as the pretreatment intensity increased. Mathematical modelling revealed that ultrasonication had a higher effect on the methane yield than on the hydrolysis rate. A preliminary energy assessment indicated that the methane yield increase was not high enough as to compensate the electricity requirement of ultrasonication without biomass dewatering (8% VS).     

How do people select plants for use? Matching the Ecological Apparency Hypothesis with Optimal Foraging Theory

The present study aimed to understand human plant resource usage strategies in the context of the Ecological Apparency Hypothesis and Optimal Foraging Theory. The relationship between plant resource knowledge and availability was tested in a rural community (Palmital) in a dry Atlantic Forest fragment in the state of Minas Gerais, Southeastern Brazil, using data from phytosociological studies and interviews. We considered both total use and separate use categories. Use Value (UV) was significantly associated with all of the analyzed ecological variables, but there was an association with relative dominance and a weak relationship with relative density. When the UVs were separately analyzed for each category, we found that some, i.e., fuel and construction, corroborate the Ecological Apparency Hypothesis, while others do not, particularly the medicinal and food categories. In addition, we found large differences with respect to the ecological variables that best correlated with UV. The data suggest that the cost/benefit relationship predicted by Optimal Foraging Theory can explain the Ecological Apparency Hypothesis when the following factors are considered: (a) resource acquisition optimization and security; (b) a higher probability of acquiring more abundant species during random collection events; and (c) differential utilization patterns (distinct requirements for a specific use) for each use category. Some implications for conservation are also discussed.     

Determinants of exposure to mercury in hair from inhabitants of the largest mercury mine in the world

Mercury exposure of the local population was assessed in two areas of the Almadén mercury mining district, Spain, which has been the world’s largest producer of this element. Two groups, who are exposed to different sources of mercury, from a point source in Almadén and a diffuse source hundreds of kilometres away in the same region, were studied. Total mercury (THg) in human hair ranged from 0.20 to 9.35 mg kg⁻¹ and the mean value was 2.64 mg kg⁻¹. About 87% of subjects had THg levels in excess of the EPA reference dose (RfD = 1.0 mg kg⁻¹), while a high percentage (68%) of them live in Almadén. There was a clear increase in hair Hg with reported fish consumption and the highest mean hair mercury level was 4 times the RfD in a group who had reported the highest consumption of fish. For the whole group, there was a significant effect of age, gender and fish consumption in relation to Hg concentration in the hair. Nevertheless, when both groups were tested separately by means of a multivariate regression model, there was significant exposure in those living near the mine area. Several factors such as age, gender and fish consumption remained statistically significant and were associated with THg. The main conclusion is that people living close to the hot spot are more impacted by mercury than people living further away. The intake of Hg through consumption of fish is an important parameter for Hg exposure; however, in the case of people living close to the hot spot, their levels are related to the highly Hg-impacted living environment.     

Public engagement on urban air pollution: an exploratory study of two interventions

The use of portable sensors to measure air quality is a promising approach for the management of urban air quality given its potential to improve public participation in environmental issues and to promote healthy behaviors. However, not all the projects that use air quality mobile sensors consider the potential effects of their use on the attitudes and behaviors of non-expert individuals. This study explores the experiences, perceptions, attitudes, and behavioral intentions of 12 participants who used a real-time NO₂ sensor over a period of 7 days in the metropolitan area of Barcelona and compares them with 16 participants who did not have access to the device but rather to documentary information. The study design is based on recombined focus groups who met at the beginning and end of a 7-day activity. The results suggest that the experience with the sensors, in comparison with the traditional information, generates greater motivation among participants. Also, that the use of the sensor seems to support a more specific awareness of the problem of air pollution. In relation to risk perception, the textual and visual information seems to generate stronger beliefs of severity among participants. In both groups, beliefs of low controllability and self-efficacy are observed. Neither using the sensor nor reading the documentary information seems to contribute positively in this sense. The results of the study aim to contribute to the design of public involvement strategies in urban air pollution.     

Butyltin occurrence and risk assessment in the sediments of the Iberian Peninsula

The occurrence of butyltin (BT) compounds in more than 50 recent sediment samples of the Iberian Peninsula, collected in the harbours of the western Mediterranean Sea (Spain) and the North Atlantic Ocean (Portugal), including domestic and industrial sewage disposal sites, has been assessed. The highest levels of tributyltin (TBT) (7673 μg kg^?1 dry wt.) were detected in commercial harbours associated with inputs from large vessels. However, relatively high TBT values (about 2150 μg kg^?1 dry wt.) were also detected in fishing and recreational boating areas. Spanish marinas and harbours are more polluted in terms of TBT (5–7673 μg kg^?1 dry wt.) compared to those in Portugal (4–12 μg kg^?1 dry wt.). Generally, the Mediterranean sediments show a BT distribution characterized by the predominance of TBT over the degradation products dibutyl (DBT) and monobutyltin (MBT), indicating the presence of recent inputs, in contrast to the Portuguese coastal distribution. Calculation of butyltin degradation indexes (BDI) confirmed a different trend, depending on the area. Furthermore, a comparative study of the occurrence of BT in different sewage sludge disposal sites shows that domestic primary sewage sludge effluents can contribute to coastal BT pollution, but to a lesser extent when compared with harbours. Historical trends (1995–2003) for Barcelona harbour reveal that BT regulations on the use of TBT-based antifouling paints have not been fully effective. Finally, a comparison against the existing sediment quality guidelines (SQGs) indicated that acute toxic effects could only be expected for TBT in some Mediterranean harbours; conversely, in every North Atlantic Ocean station, a lesser environmental threat for the harbour benthic community is expected.     

Functional group influences on the reactive azo dye decolorization performance by electrochemical oxidation and electro-Fenton technologies

Electrochemical water treatment technologies are highly promising to achieve complete decolorization of dyebath effluents, as demonstrated by several studies reported in the literature. However, these works are focused on the treatment of one model pollutant and generalize the performances of the processes which are not transposable since they depend on the pollutant treated. Thus, in the present study, we evaluate, for the first time, the influence of different functional groups that modify the dye structure on the electrochemical process decolorization performance. The textile azo dyes Reactive Orange 16, Reactive Violet 4, Reactive Red 228, and Reactive Black 5 have been selected because they present the same molecular basis structure with different functional groups. The results demonstrate that the functional groups that reduce the nucleophilicity of the pollutant hinder the electrophilic attack of electrogenerated hydroxyl radical. Thereby, the overall decolorization efficiency is consequently reduced as well as the decolorization rate. Moreover, the presence of an additional chromophore azo bond in the molecule enhances the recalcitrant character of the azo dyes as pollutants. The formation of a larger and more stable conjugated π system increases the activation energy required for the electrophyilic attack of ^?OH, affecting the performance of electrochemical technologies on effluent decolorization.     

The SEAP in the city of Girona,a crossroads between boldness and pragmatism

The Covenant of Mayors has secured the commitments of over 5400 European Cities (as of December 2013) to achieving the European Union 20-20-20 climate change mitigation targets by 2020 through action at the local level. Due to the youth of the initiative, few experiences have been reported in the academic literature. We study the development of the Sustainable Energy Action Plan (SEAP) in the city of Girona (Catalonia, Spain) to analyse the opportunities and challenges this process may present in a small- to medium-sized, compact Mediterranean city. This knowledge can provide information to local authorities in similar municipalities, technical teams and decision-makers at the European level interested in enhancing the performance of such plans in the future. In this article, we explain how the SEAP was developed in Girona, the main results and proposed actions, and discuss the main setbacks. We conclude that an overarching European oversight organism is advisable to coordinate and aid local efforts.