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Environments
Volume 8
Issue 1
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Environments, Volume 8, Issue 1 (January 2021) – 6 articles

Cover Story (view full-size image): Reductions in air pollution in Sydney under lockdown, though modest, were in striking contrast to the smoke-filled skies experienced during bushfires just months before. The drama of such changes was enhanced in iconic false-colour satellite images. Decreased use of transport and low electricity demand kept primary pollutant emissions low. People surveyed in Australia believed air pollution improved after lockdown, and searches on Google using terms such as air quality and haze were more frequent during the bushfires than under lockdown. Although changes in air pollutants during COVID-19 have been subtle, perceptions suggest dramatic improvements to air quality. View this paper
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15 pages, 3909 KiB  
Article
Water Quality Monitoring with Arduino Based Sensors
by Wong Jun Hong, Norazanita Shamsuddin, Emeroylariffion Abas, Rosyzie Anna Apong, Zarifi Masri, Hazwani Suhaimi, Stefan Herwig Gödeke and Muhammad Nafi Aqmal Noh
Environments 2021, 8(1), 6; https://doi.org/10.3390/environments8010006 - 14 Jan 2021
Cited by 74 | Viewed by 49773
Abstract
Water is a quintessential element for the survival of mankind. Its variety of uses means that it is always in a constant state of demand. The supply of water most primarily comes from large reservoirs of water such as lakes, streams, and the [...] Read more.
Water is a quintessential element for the survival of mankind. Its variety of uses means that it is always in a constant state of demand. The supply of water most primarily comes from large reservoirs of water such as lakes, streams, and the ocean itself. As such, it is good practice to monitor its quality to ensure it is fit for human consumption. Current water quality monitoring is often carried out in traditional labs but is time consuming and prone to inaccuracies. Therefore, this paper aims to investigate the feasibility of implementing an Arduino-based sensor system for water quality monitoring. A simple prototype consisting of a microcontroller and multiple attached sensors was employed to conduct weekly onsite tests at multiple daily intervals. It was found that the system works reliably but is reliant on human assistance and prone to data inaccuracies. The system however, provides a solid foundation for future expansion works of the same category to elevate the system to being Internet of Things (IoT) friendly. Full article
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5 pages, 204 KiB  
Editorial
Acknowledgment to Reviewers of Environments in 2020
by Environments Editorial Office
Environments 2021, 8(1), 5; https://doi.org/10.3390/environments8010005 - 13 Jan 2021
Viewed by 2971
Abstract
Peer review is the driving force of journal development, and reviewers are gatekeepers who ensure that Environments maintains its standards for the high quality of its published papers [...] Full article
21 pages, 4195 KiB  
Article
Factors Affecting Alkali Activation of Laterite Acid Leaching Residues
by Konstantinos Komnitsas, Georgios Bartzas, Vasiliki Karmali and Evangelos Petrakis
Environments 2021, 8(1), 4; https://doi.org/10.3390/environments8010004 - 10 Jan 2021
Cited by 13 | Viewed by 4218
Abstract
In this experimental study, the alkali activation of acid leaching residues using a mixture of sodium hydroxide (NaOH) and alkaline sodium silicate solution (Na2SiO3) as activators is investigated. The residues were also calcined at 800 and 1000 °C for [...] Read more.
In this experimental study, the alkali activation of acid leaching residues using a mixture of sodium hydroxide (NaOH) and alkaline sodium silicate solution (Na2SiO3) as activators is investigated. The residues were also calcined at 800 and 1000 °C for 2 h or mixed with metakaolin (MK) in order to increase their reactivity. The effect of several parameters, namely the H2O/Na2O and SiO2/Na2O ratios present in the activating solution, the pre–curing time (4–24 h), the curing temperature (40–80 °C), the curing time (24 or 48 h), and the ageing period (7–28 days) on the properties of the produced alkali activated materials (AAMs), including compressive strength, porosity, water absorption, and density, was explored. Analytical techniques, namely X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and elemental mapping analysis were used for the identification of the morphology and structure of the final products. The experimental results show that the laterite acid leaching residues cannot be alkali activated in an unaltered state, and the compressive strength of the produced AAMs barely reaches 1.4 MPa, while the mixing of the residues with 10 wt% metakaolin results in noticeably higher compressive strength (41 MPa). Moreover, the calcination of residues at 800 and 1000 °C has practically no beneficial effect on alkali activation. Alkali activated materials produced under the optimum synthesis conditions were subjected to high temperature firing for 2 h and immersed in distilled water or acidic solution (1 mol L−1 HCl) for 7 and 30 days in order to assess their structural integrity under different environmental conditions. This study explores the potential of alkali activation of laterite leaching residues amended with the addition of metakaolin for the production of AAMS that can be used as binders or in several construction applications in order to enable their valorization and also improve the environmental sustainability of the metallurgical sector. Full article
(This article belongs to the Special Issue Feature Papers in Environments in 2020)
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22 pages, 3519 KiB  
Article
Assessing the Ecotoxicity of Soil Affected by Wildfire
by Petra Martínez Barroso, Magdalena Daria Vaverková and Jakub Elbl
Environments 2021, 8(1), 3; https://doi.org/10.3390/environments8010003 - 7 Jan 2021
Cited by 4 | Viewed by 3708
Abstract
This study was carried out to assess the ecotoxicity of soil affected by wildfire using two laboratory toxicity tests, and to investigate the possibility of application of selected soil amendment into the burnt soil in order to improve its properties for faster post-fire [...] Read more.
This study was carried out to assess the ecotoxicity of soil affected by wildfire using two laboratory toxicity tests, and to investigate the possibility of application of selected soil amendment into the burnt soil in order to improve its properties for faster post-fire reclamation. A phytotoxicity test is a fast-indicative test for revealing acute toxicity and was performed on quickly growing plant species Sinapis alba L. and Lepidium sativum L., while a pot experiment is a standardized toxicity test with a longer experiment duration and was carried out with Lolium perenne L., Festuca rubra L., Brassica juncea L. Diatomite, bentonite, compost, and biochar were supplemented to the soil. Regarding the phytotoxicity test only 3% w/w of biochar stimulated the growth of Lepidium sativum L. Pot experiment confirmed that effect of soil application amendments on biomass yield is more significant than the plant species. The average highest biomass yields were achieved in treatments with bentonite and diatomite. Subsequent research should focus on investigating possible combinations of soil amendments for burnt soil reclamation and complementing the experiments with chemical analysis. Full article
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15 pages, 12328 KiB  
Article
Subtle Changes or Dramatic Perceptions of Air Pollution in Sydney during COVID-19
by Peter Brimblecombe and Yonghang Lai
Environments 2021, 8(1), 2; https://doi.org/10.3390/environments8010002 - 1 Jan 2021
Cited by 11 | Viewed by 6128
Abstract
The COVID-19 pandemic made it critical to limit the spread of the disease by enforcing human isolation, restricting travel and reducing social activities. Dramatic improvements to air quality, especially NO2, have often characterised places under COVID-19 restrictions. Air pollution measurements in [...] Read more.
The COVID-19 pandemic made it critical to limit the spread of the disease by enforcing human isolation, restricting travel and reducing social activities. Dramatic improvements to air quality, especially NO2, have often characterised places under COVID-19 restrictions. Air pollution measurements in Sydney in April 2019 and during the lockdown period in April 2020 show reduced daily averaged NO2 concentrations: 8.52 ± 1.92 and 7.85 ± 2.92 ppb, though not significantly so (p1~0.15) and PM2.5 8.91 ± 4.94 and 7.95 ± 2.64 µg m−3, again a non-significant difference (p1~0.18). Satellite imagery suggests changes that parallel those at ground level, but the column densities averaged over space and time, in false-colour, are more dramatic. Changed human mobility could be traced in increasing times spent at home, assessed from Google Mobility Reports and mirrored in decreased traffic flow on a major road, suggesting compliance with the restrictions. Electricity demand for the State of New South Wales was low under lockdown in early April 2020, but it recovered rapidly. Analysis of the uses of search terms: bushfires, air quality, haze and air pollution using Google Trends showed strong links between bushfires and pollution-related terms. The smoke from bushfires in late 2019 may well have added to the general impression of improved air quality during lockdown, despite only modest changes in the ground level measurements. This gives hints that successful regulation of air quality requires maintaining a delicate balance between our social perceptions and the physical reality. Full article
(This article belongs to the Special Issue Response to Current Air Quality Changes in Small and Large Areas)
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3 pages, 166 KiB  
Editorial
New Insights into Impacts of Toxic Metals in Aquatic Environments
by Elise David and Claudia Cosio
Environments 2021, 8(1), 1; https://doi.org/10.3390/environments8010001 - 30 Dec 2020
Cited by 8 | Viewed by 3195
Abstract
Chemical contamination of the aquatic environment, as a consequence of anthropogenic activities, remains of major worldwide concern [...] Full article
(This article belongs to the Special Issue New Insights into Impacts of Toxic Metals in Aquatic Environments)
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