Environments, Volume 5, Issue 5 (May 2018) – 12 articles

PM_2.5 samples were collected from January 2009 to January 2010 at two sampling sites located in the downtown (Centro) and toward the southwest (Miravalle) in the city of Guadalajara, Mexico. The environmental concentrations of 14 selected polycyclic aromatic hydrocarbons (PAHs) in PM_2.5 were identified and quantified. The most abundant PAHs in PM_2.5 samples were benzo[ghi]perylene, indeno[1,2,3-cd]pyrene, benzo[b]fluoranthene, benzo[a]pyrene and benzo[k]fluoranthene, accounting for approximately 75% of the total PAHs. The total PAH concentrations at the two sampling sites ranged from 0.65 to 19.62 ng·m⁻³. Spatial variations were found during the dry-warm season, which were attributed mainly to differing intensities of local traffic and less dispersion of air pollutants in Miravalle. Seasonal variations were associated with increases in rainfall (June-September) and differences in temperature (January–May and October–January). The benzo(a)pyrene-equivalent (BaPE) and BaP results suggest that exposure to PM_2.5-containing carcinogenic PAHs (C-PAHs) in Miravalle during the warm-dry and cold-dry seasons can be seen as representing a serious risk to human health. The contributions from potential sources to PAHs in PM_2.5 were evaluated by the diagnostic ratios between PAHs and principal component analysis (PCA). In the whole sampling period, vehicular emission activity, probably related to light and heavy traffic, was found to be the predominant contributor to PM_2.5-bound PAHs. Full article

Drinking water quality is determined by the water’s biological, chemical, and physical features. Water sampling was carried out in 20 villages in the Pune and Satara districts of Maharashtra, with 15 falling in a low rainfall zone. Samples were collected from rivers, open wells, and bore wells, four times in a period of a year covering all seasons. A total of 206 water samples were analyzed for their physical, chemical, and bacteriological properties. Physical and chemical properties were expressed in the form of a modified Water Quality Index (WQI). Additionally, the modified WQI was compared to an Overall Pollution Index (OIP) for rivers. The present investigation is an attempt to analyze the impact of seasonal changes on water quality of different water bodies using two different WQIs. To understand the degree to which water quality is affected by faecal bacteria, modified WQI with exclusion of faecal coliforms (FC) and OIP with inclusion of FC were compared with each other in river water bodies. Modified WQI values and bacterial counts were at a maximum during the onset of the monsoon. In terms of bacteriological contamination, the number of FC and intestinal enterococci (IE) in the water bodies was of major concern since it would impact human health. Full article

The growth of the green microalga Raphidocelis subcapitata in sodium alginate beads was studied. The beads were generated by the extrusion technique, which was followed by gelling in a Ca²⁺ solution. The alginate concentrations studied were 1%, 1.5% and 2% (w/v), while the concentrations of CaCl₂ were 0.2%, 0.5% and 1% (w/v). The growth monitoring of the cells in the beads was performed by dissolving the gel in a sodium phosphate buffer and reading the optical density at 685 nm using a spectrophotometer. The results clearly showed that alginate and divalent Ca²⁺ ions do not contribute directly to the growth of microalgae but play a decisive role in preserving the integrity of the beads and protecting them from shrinkage. Furthermore, they have an important role in the transfer of nutrients, light and CO₂ in the beads. The highest growth (3.92 × 10⁶ ± 0.39 cells/bead) was obtained with the concentrations of alginate being 1.5% and CaCl₂ being 0.2%. However, the beads began to shrink and this resulted in the cells being released into the culture medium after the 8th day. Of all the combinations studied, the combination of 2% alginate and 1% CaCl₂ was the best because it ensured the stability of the beads during the 10 days of culture and resulted in a low concentration of free cells detected in the culture medium. These concentrations were determined as the optimal conditions for the immobilization of microalgae and will be used in the following work. Full article

Considered the second biggest risk factor for lung cancer in humans after smoking, indoor radon gas (²²²Rn) is produced by the radioactive decay of ²²⁶Ra, which is mainly present in building materials and soil. The current study proposes a methodology for estimating radon levels inside a dwelling using the multizone airflow and contaminant transport modeling software CONTAM, with the main purpose to improve indoor air quality by optimizing mechanical ventilation. The generation rate of indoor radon sources was investigated in relation to the total surface of each room and was subsequently used for identifying the rooms that require special attention. The methodology described should assist in modeling indoor radon contamination, which can be used to optimize the ventilation in a dwelling. Full article

Soundscape has been growing steadily as a research field since its interdisciplinary concepts were first introduced about 50 years ago in music theory and acoustic ecology, and it currently affects a broad spectrum of disciplines ranging from social sciences to urban planning and noise control engineering. In spite of its strong research appeal, it is not clear what the actual impact and outreach of soundscape science is at a societal level; that is: how soundscape research is received by community. Using the Altmetric database, this review aims to map how and where soundscape research is “mentioned”, considering the number of mentions over time, their geographical spread and effectiveness of publication outlets. Results show that mentions are growing with time, they mostly originate in the United States and the United Kingdom, and they are generated by a limited number of research items. Full article

A single energy-based technology has been the traditional approach to supplying basic energy needs, but its limitations give rise to other viable options. Renewable off-grid electricity supply is one alternative that has gained attention, especially with areas lacking a grid system. The aim of this paper is to present an optimal hybrid energy system to meet the electrical demand in a reliable and sustainable manner for an off-grid remote village, Gwakwani, in South Africa. Three off-grid systems have been proposed: (i) Photovoltaic (PV) systems with a diesel generator; (ii) Photovoltaic systems and battery storage; and (iii) Photovoltaic systems with diesel generator and battery storage. For this analysis, different size of photovoltaic panels were tested and the optimal size in each scenario was chosen. These PV sizes were 1, 0.8, 0.6 and 0.4 kW. The optimization between these sizes was built based on three main objectives. These objectives are: (i) energy demand satisfaction; (ii) system cost; and (iii) pollution. For the first and second system scenarios, the optimal size was the 1 kW with battery and 1 kW with diesel generator; the third scenario results did not sufficiently match the three objectives. A general comparison has been carried out between the two optimal systems when the diesel generator is used and when the battery is applied. Both scenarios can sufficiently meet the demand without any considerable interruption, but disparities exist between them in relation to cost and technical optimization. There is a huge difference in the cost between these scenarios. The total cost in PV-Battery system (Scenario 1) represents only 26% of the entire PV system. Also, the PV and Battery system does not release any harmful emissions compared with nearly 6 tCO₂/year in the PV with Diesel system (Scenario 2). Also, Scenario (3) is a viable option in terms of energy production but costs more and is proposed to be more beneficial using an economies-of-scale analysis. Full article

Urban environments are characterised by the presence of copious and unstructured noise. This noise continuously challenges speech intelligibility both in normal-hearing and hearing-impaired individuals. In this paper, we investigate the impact of urban noise, such as traffic, on speech identification and, more generally, speech understanding. With this purpose, we perform listening experiments to evaluate the ability of individuals with normal hearing to detect words and interpret conversational speech in the presence of urban noise (e.g., street drilling, traffic jams). Our experiments confirm previous findings in different acoustic environments and demonstrate that speech identification is influenced by the similarity between the target speech and the masking noise also in urban scenarios. More specifically, we propose the use of the structural similarity index to quantify this similarity. Our analysis confirms that speech identification is more successful in presence of noise with tempo-spectral characteristics different from speech. Moreover, our results show that speech comprehension is not as challenging as word identification in urban sound environments that are characterised by the presence of severe noise. Indeed, our experiments demonstrate that speech comprehension can be fairly successful even in acoustic scenes where the ability to identify speech is highly reduced. Full article

The groundwater recharge mechanism in the hyper-arid Gobi Desert of Northwestern China was analyzed using water balance and tracer-based approaches. Investigations of evaporation, soil water content, and their relationships with individual rainfall events were conducted from April to August of 2004. Water sampling of rainwater, groundwater, and surface water was also conducted. During this period, 10 precipitation events with a total amount of 41.5 mm, including a maximum of 28.9 mm, were observed. Evaporation during the period was estimated to be 33.1 mm. Only the soil water, which was derived from the heaviest precipitation, remained in the vadose zone. This is because a dry surface layer, which was formed several days after the heaviest precipitation event, prevented evaporation. Prior to that, the heaviest precipitation rapidly infiltrated without being affected by evaporation. This is corroborated by the isotopic evidence that both the heaviest precipitation and the groundwater retained no trace of significant kinetic evaporation. Estimated δ-values of the remaining soil water based on isotopic fractionation and its mass balance theories also demonstrated no trace of kinetic fractionation in the infiltration process. Moreover, stable isotopic compositions of the heaviest precipitation and the groundwater were very similar. Therefore, we concluded that the high-intensity precipitation, which rapidly infiltrated without any trace of evaporation, was the main source of the groundwater. Full article

Governing forest ecosystem services as a forest socio-ecological system is an evolving concept in the face of different environmental and social challenges. Therefore, different modes of ecosystem governance such as hierarchical, scientific–technical, and adaptive–collaborative governance have been developed. Although each form of governance offers important features, no one form on its own is sufficient to attain sustainable environmental governance (SEG). Thus, the blending of important features of each mode of governance could contribute to SEG, through a combination of both hierarchical and collaborative governance systems supported by scientifically and technically aided knowledge. This should be further reinforced by the broad engagement of stakeholders to ensure the improved well-being of both ecosystems and humans. Some form of governance and forest management measures, including sustainable forest management, forest certification, and payment for ecosystem services mechanisms, are also contributing to that end. While issues around commodification and putting a price on nature are still contested due to the complex relationship between different services, if these limitations are taken into account, the governance of forest ecosystem services will serve as a means of effective environmental governance and the sustainable management of forest resources. Therefore, forest ecosystem services governance has a promising future for SEG, provided limitations are tackled with due care in future governance endeavors. Full article

Models are increasingly used to estimate and pre-emptively calculate the occupational exposure of airborne released particulate matter. Typical two-box models assume instant and fully mixed air volumes, which can potentially cause issues in cases with fast processes, slow air mixing, and/or large volumes. In this study, we present an aerosol dispersion model and validate it by comparing the modelled concentrations with concentrations measured during chamber experiments. We investigated whether a better estimation of concentrations was possible by using different geometrical layouts rather than a typical two-box layout. A one-box, two-box, and two three-box layouts were used. The one box model was found to underestimate the concentrations close to the source, while overestimating the concentrations in the far field. The two-box model layout performed well based on comparisons from the chamber study in systems with a steady source concentration for both slow and fast mixing. The three-box layout was found to better estimate the concentrations and the timing of the peaks for fluctuating concentrations than the one-box or two-box layouts under relatively slow mixing conditions. This finding suggests that industry-relevant scaled volumes should be tested in practice to gain more knowledge about when to use the two-box or the three-box layout schemes for multi-box models. Full article