Water

13 pages, 2124 KiB

Open AccessArticle

Novel Protocol for Acute In Situ Ecotoxicity Test Using Native Crustaceans Applied to Groundwater Ecosystems

by Andrea Castaño-Sánchez, Florian Malard, Gabriela Kalčíková and Ana Sofia P. S. Reboleira

Water 2021, 13(8), 1132; https://doi.org/10.3390/w13081132 - 20 Apr 2021

Cited by 10 | Viewed by 2944

Current standardized laboratory test protocols use model species that have limitations to accurately assess native species responses to stressors. We developed and tested a novel acute in situ protocol for testing field-collected organisms. We used Asellus aquaticus and NaCl as a reference toxicant [...] Read more.

Current standardized laboratory test protocols use model species that have limitations to accurately assess native species responses to stressors. We developed and tested a novel acute in situ protocol for testing field-collected organisms. We used Asellus aquaticus and NaCl as a reference toxicant to test for the effects of location (laboratory vs. in situ), medium (synthetic vs. field water), substrate (presence vs. absence), and protocol replicability. We further tested the protocol using groundwater-adapted isopods: Proasellus assaforensis for the effect of location, P. cavaticus of medium and P.lusitanicus of substrate. Our results showed that A.aquaticus’ lethality obtained with the novel acute in situ protocol did not significantly differ from those from laboratory testing. However, laboratory tested P.assaforensis showed a higher sensitivity, suggesting that its acclimation to laboratory conditions might have pernicious effects. A. aquaticus and P. cavaticus showed a higher mortality using synthetic medium in situ and under laboratory conditions, which overestimated the stressor’s effect. Besides, substrate use had no significant effect. The novel acute in situ protocol allows the use of native species under realistic scenarios. It is particularly well adapted for assessing the risk of groundwater ecosystems but it can be applied to a wide range of ecosystems. Full article

(This article belongs to the Section Water Quality and Contamination)

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20 pages, 4519 KiB

Open AccessFeature PaperArticle

Laboratory and In Situ Determination of Hydraulic Conductivity and Their Validity in Transient Seepage Analysis

by Soonkie Nam, Marte Gutierrez, Panayiotis Diplas and John Petrie

Water 2021, 13(8), 1131; https://doi.org/10.3390/w13081131 - 20 Apr 2021

Cited by 6 | Viewed by 4622

Abstract

This paper critically compares the use of laboratory tests against in situ tests combined with numerical seepage modeling to determine the hydraulic conductivity of natural soil deposits. Laboratory determination of hydraulic conductivity used the constant head permeability and oedometer tests on undisturbed Shelby [...] Read more.

This paper critically compares the use of laboratory tests against in situ tests combined with numerical seepage modeling to determine the hydraulic conductivity of natural soil deposits. Laboratory determination of hydraulic conductivity used the constant head permeability and oedometer tests on undisturbed Shelby tube and block soil samples. The auger hole method and Guelph permeameter tests were performed in the field. Groundwater table elevations in natural soil deposits with different hydraulic conductivity values were predicted using finite element seepage modeling and compared with field measurements to assess the various test results. Hydraulic conductivity values obtained by the auger hole method provide predictions that best match the groundwater table’s observed location at the field site. This observation indicates that hydraulic conductivity determined by the in situ test represents the actual conditions in the field better than that determined in a laboratory setting. The differences between the laboratory and in situ hydraulic conductivity values can be attributed to factors such as sample disturbance, soil anisotropy, fissures and cracks, and soil structure in addition to the conceptual and procedural differences in testing methods and effects of sample size. Full article

(This article belongs to the Section Hydrology)

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13 pages, 426 KiB

Open AccessArticle

Research on Sustainable Development Evaluation of Reservoir Water Source Area in Island Area

by Jo-Hung Yu, Hsiao-Hsien Lin, Yu-Chih Lo, Kuan-Chieh Tseng and Chin-Hsien Hsu

Water 2021, 13(8), 1130; https://doi.org/10.3390/w13081130 - 20 Apr 2021

Cited by 5 | Viewed by 2033

Abstract

This study takes Taiwan’s Sun Moon Lake Reservoir as the research object to discuss the sustainable development decision-making of the reservoir water source area in the island area. The grounded theory was adopted to construct the framework; 835 questionnaires were analyzed by statistical [...] Read more.

This study takes Taiwan’s Sun Moon Lake Reservoir as the research object to discuss the sustainable development decision-making of the reservoir water source area in the island area. The grounded theory was adopted to construct the framework; 835 questionnaires were analyzed by statistical test; 10 interviewees’ feelings were collected through interviews and discussions, and multiple verification methods were used for exploration. Conclusion: The study found that the current development of the reservoir water source area of the outlying islands has brought much garbage; affecting the quality of the natural environment; lake; and water source; caused the disappearance of distinctive culture and architecture. The poor interaction between businesses and communities has led to an overlap in the types of industries, consumer goods, attractions and a lack of transportation and medical facilities, affecting people’s desire to travel. The government’s future decisions include: Increasing the variety of consumer goods; improving medical and transportation facilities; preserving unique culture and architecture; linking foreign-invested enterprises with community interactivity; enhancing local people’s interaction; and compensating for the deficiencies in human resources for industrial development are the key points for future improvement of the reservoir water source area of the outlying islands. Full article

(This article belongs to the Special Issue Management and Monitoring of Urban and Rural Ecological Water Resources)

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18 pages, 2382 KiB

Open AccessFeature PaperArticle

Erythromycin Abatement from Water by Electro-Fenton and Peroxyelectrocoagulation Treatments

by Anna Serra-Clusellas, Luca Sbardella, Pol Herrero, Antoni Delpino-Rius, Marc Riu, María de Lourdes Correa, Anna Casadellà, Núria Canela and Xavier Martínez-Lladó

Water 2021, 13(8), 1129; https://doi.org/10.3390/w13081129 - 20 Apr 2021

Cited by 5 | Viewed by 3303

Abstract

Electro-Fenton (EF) and peroxyelectrocoagulation (PEC) processes were investigated to mineralize 10 mg L⁻¹ erythromycin from ultrapure water, evaluating the influence of the anode material (BDD and Fe), current density (j_anode) (5 mA cm⁻² and 10 mA cm⁻² [...] Read more.

Electro-Fenton (EF) and peroxyelectrocoagulation (PEC) processes were investigated to mineralize 10 mg L⁻¹ erythromycin from ultrapure water, evaluating the influence of the anode material (BDD and Fe), current density (j_anode) (5 mA cm⁻² and 10 mA cm⁻²), oxygen flowrate injected to the cathode (0.8 L min⁻¹ O₂ and 2.0 L min⁻¹ O₂) and pH (2.8, 5.0 and 7.0) on the process efficiency and the electricity costs. 70% mineralization was reached after applying 0.32 A h L⁻¹ under the best operational conditions: PEC treatment at 5 mA cm⁻², 2.0 L min⁻¹ O₂ and pH 2.8. The electricity consumption of the electrochemical cell under these conditions was approximately 0.3 kWh m⁻³. Early-stage intermediates produced from erythromycin degradation were identified and quantified throughout the treatment and a potential erythromycin degradation pathway was proposed. The most appropriate operational conditions tested with synthetic solutions were applied to treat a real effluent from the tertiary treatment of an urban wastewater treatment plant. All emerging compounds listed in the EU Decision 2018/840 (Watch List 2018) were determined before and after the PEC treatment. All listed pollutants were degraded below their quantification limit, except estrone and 17-α-ethinylestradiol which were 99% removed from water. Electricity consumption of the electrochemical cell was 0.4 kWh m⁻³. Whilst awaiting future results that demonstrate the innocuity of the generated byproducts, the results of this investigation (high removal yields for emerging pollutants together with the low electricity consumption of the cell) indicate the promising high potential of PEC treatment as a water treatment/remediation/regeneration technology. Full article

(This article belongs to the Special Issue Advanced Oxidation Processes for Water and Wastewater Treatment)

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18 pages, 3018 KiB

Open AccessArticle

Mediating the Effects of Climate on the Temperature and Thermal Structure of a Monomictic Reservoir through Use of Hydraulic Facilities

by Maurice Alfonso Duka, Tetsuya Shintani and Katsuhide Yokoyama

Water 2021, 13(8), 1128; https://doi.org/10.3390/w13081128 - 20 Apr 2021

Cited by 3 | Viewed by 2795

Abstract

Climate warming can alter the thermal conditions of reservoirs. However, some hydraulic interventions can be explored to mitigate this impact. This study investigates the long-term effects of climate on the temperature and thermal structure of a monomictic reservoir that has had varying operations [...] Read more.

Climate warming can alter the thermal conditions of reservoirs. However, some hydraulic interventions can be explored to mitigate this impact. This study investigates the long-term effects of climate on the temperature and thermal structure of a monomictic reservoir that has had varying operations from 1959 to 2016. Reservoir progressively operated through three distinct periods, namely, (A) deep penstock withdrawal (DPW; 1959–1991), (B) purely selective withdrawal (SW; 1992–2001), and (C) combination of SW and vertical curtain (VC; 2002–2016). Although annual air temperatures are increasing (+0.15 °C decade⁻¹) in the long term, the reservoir’s surface water temperatures have been found to be decreasing (−0.06 °C decade⁻¹). Periods B and C produced colder profiles and exhibited lower heat content and higher potential energy anomaly than Period A. Furthermore, stronger thermoclines, as indicated by Brunt–Vaisala frequency, were observed in the two latter periods. The results of this study show that varying operations bear a stronger influence on the reservoir’s temperature and thermal structure than climate change itself. Mitigating the thermal impacts of climate warming in reservoirs appears promising with the use of SW and VC. Full article

(This article belongs to the Section Water Resources Management, Policy and Governance)

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Graphical abstract

17 pages, 1343 KiB

Open AccessArticle

Groundwater Quality Evaluation of the Dawu Water Source Area Based on Water Quality Index (WQI): Comparison between Delphi Method and Multivariate Statistical Analysis Method

by Zhizheng Liu, Henghua Zhu, Xiaowei Cui, Wei Wang, Xiaoyu Luan, Lu Chen, Zhaojie Cui and Long Zhang

Water 2021, 13(8), 1127; https://doi.org/10.3390/w13081127 - 20 Apr 2021

Cited by 10 | Viewed by 2587

Abstract

Water quality in the Dawu water source area is primarily studied through the traditional water quality assessment method that measures the chemical parameters of water against the existing standards, which is simple but cannot accurately describe the water quality. Although the water quality [...] Read more.

Water quality in the Dawu water source area is primarily studied through the traditional water quality assessment method that measures the chemical parameters of water against the existing standards, which is simple but cannot accurately describe the water quality. Although the water quality index (WQI) proposed by Horton is widely used for comprehensive water quality evaluation, parameter selection and weight determination are primarily based on the Delphi method, which is subjective and random. Moreover, in groundwater evaluation, the focus is primarily laid on general chemical parameters, such as Total Dissolved Solids, hydrogen ion concentration, Electrical Conductivity, and heavy metals, such as Hydrargyrum, Arsenic, and Chromium, with limited consideration for organic pollutants. In this study, WQI technology in combination with the entropy weight method was used to evaluate the groundwater environmental quality of the Dawu water source area, and the scientific results were analyzed by comparing the full index, Delphi, and multivariate statistical analysis methods. The results showed that the groundwater in the Dawu water source area generally had good quality and was potable and that the application of multivariate statistical analysis method was more suitable than the Delphi method in the index selection process. Full article

(This article belongs to the Section Water Quality and Contamination)

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15 pages, 1626 KiB

Open AccessFeature PaperArticle

Meeting the Salinity Requirements of the Bivalve Mollusc Crassostrea gigas in the Depuration Process and Posterior Shelf-Life Period to Improve Food Safety and Product Quality

by João A. Silvestre, Sílvia F. S. Pires, Vitória Pereira, Miguel Colaço, Ana P. L. Costa, Amadeu M. V. M. Soares, Domitília Matias, Filipa Bettencourt, Sergio Fernández-Boo, Rui J. M. Rocha and Andreia C. M. Rodrigues

Water 2021, 13(8), 1126; https://doi.org/10.3390/w13081126 - 20 Apr 2021

Cited by 8 | Viewed by 3783

Abstract

Microbiological contamination of bivalve molluscs is one of the major concerns inherent to food safety, thus depuration is frequently needed to assure food safety levels associated with their consumption. Salinity plays an important role in the metabolic activity of bivalves and as such [...] Read more.

Microbiological contamination of bivalve molluscs is one of the major concerns inherent to food safety, thus depuration is frequently needed to assure food safety levels associated with their consumption. Salinity plays an important role in the metabolic activity of bivalves and as such can influence their depuration capacity. This study aimed to evaluate the effect of salinity (25, 30, 35 and 40) on the efficiency of the depuration process, along with the quality and shelf-life of Crassostrea gigas. For this, a 24-h depuration was carried out, followed by a storage period at 5 ± 1 °C for six days. Microbiological analyses and biochemical parameters related to oxidative stress response were analysed. Escherichia coli load was reduced in only 24 h, disregarding the salinity of the system. After the shelf-life period, the activity of the antioxidant defences at salinities 35 and 40 is higher but is still not sufficient to avoid lipid peroxidation. Over time, there is a decrease in oyster metabolism probably due to being chilled and to the action of exposure to air. In sum, this study suggests salinities between 25 and 30 as preferential for the depuration process of C. gigas and subsequent quality during shelf-life. Full article

(This article belongs to the Special Issue Biomarkers: An Integrative Useful Tool for Ecotoxicolgy and Biomonitoring)

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10 pages, 479 KiB

Open AccessArticle

Dental Fluorosis in Children from Aguascalientes, Mexico: A Persistent Public Health Problem

by Osiel González Dávila

Water 2021, 13(8), 1125; https://doi.org/10.3390/w13081125 - 20 Apr 2021

Cited by 4 | Viewed by 3064

Abstract

This paper estimates the prevalence and severity of dental fluorosis among participants in the first wave of The Aguascalientes Longitudinal Study of Child Development (EDNA). The analytical sample includes 1052 children in 100 public elementary schools. Dental fluorosis is determined using the Modified [...] Read more.

This paper estimates the prevalence and severity of dental fluorosis among participants in the first wave of The Aguascalientes Longitudinal Study of Child Development (EDNA). The analytical sample includes 1052 children in 100 public elementary schools. Dental fluorosis is determined using the Modified Dean’s Index. There is a 43% general dental fluorosis prevalence, and the estimated Community Fluorosis Index is 0.99. Five municipalities report average groundwater fluoride concentrations above the official Mexican guideline value of 1.5 mg/L. In those municipalities, there is a 50% average dental fluorosis prevalence. An ordered logistic regression analysis indicates that obesity in participants increases the likelihood of suffering more severe dental fluorosis symptoms compared with normal-weight participants (OR = 1.62, p < 0.05). Households consuming tap water are more likely to have children suffering more severe dental fluorosis symptoms (OR = 1.63, p < 0.05). Children aged 8 years are more likely to present more severe dental fluorosis symptoms than their peers aged 7 years (OR = 1.37, p < 0.05). Dental fluorosis will persist as a public health problem in Aguascalientes State unless appropriate technologies for fluoride removal from water are installed and operated. Full article

(This article belongs to the Special Issue Water Quality and the Public Health)

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18 pages, 3045 KiB

Open AccessArticle

Fishing Industry Perspectives on Sea-Level Rise Risk and Adaptation

by Amanda Daria Stoltz, Manoj Shivlani and Robert Glazer

Water 2021, 13(8), 1124; https://doi.org/10.3390/w13081124 - 20 Apr 2021

Cited by 5 | Viewed by 4424

Abstract

Sea-level rise, already occurring over Florida’s coast, stands to generate a significant impact on the state’s fishing industry and coastal communities, exposing vulnerable areas and populations to extreme events and disrupting established patterns of fishery and marine resource use. Using a semi-structured interview [...] Read more.

Sea-level rise, already occurring over Florida’s coast, stands to generate a significant impact on the state’s fishing industry and coastal communities, exposing vulnerable areas and populations to extreme events and disrupting established patterns of fishery and marine resource use. Using a semi-structured interview approach, this study evaluated fishing industry perspectives on sea-level rise risk and adaptation in three Florida coastal communities. The results showed that adaptation responses vary across industry sectors and communities and are strongly influenced by experience, community dynamics, and age. Generally, older fishers are less willing to relocate due to social factors, such as strong place attachment, compared to younger fishers, who are more likely to retreat and/or work from a less vulnerable location. These findings suggest that adaptation responses, while influenced by experience, are mediated by age, attachment to place, and worldviews, and that these factors need to be accounted for when crafting adaptation strategies across coastal communities. Full article

(This article belongs to the Special Issue Adaptation to Coastal Climate Change and Sea-Level Rise)

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17 pages, 1394 KiB

Open AccessFeature PaperArticle

Long-Term Oxbow Lake Trophic State under Agricultural Best Management Practices

by Richard E. Lizotte, Jr., Lindsey M. W. Yasarer, Ronald L. Bingner, Martin A. Locke and Scott S. Knight

Water 2021, 13(8), 1123; https://doi.org/10.3390/w13081123 - 20 Apr 2021

Cited by 2 | Viewed by 2224

Abstract

A key principle of agricultural best management practices (BMPs) is to improve water quality by reducing agricultural-sourced nutrients and associated eutrophication. Long-term (1998–2016) lake summer trophic state index (TSI) trends of an agricultural watershed with agricultural best management practices (BMPs) were assessed. Structural [...] Read more.

A key principle of agricultural best management practices (BMPs) is to improve water quality by reducing agricultural-sourced nutrients and associated eutrophication. Long-term (1998–2016) lake summer trophic state index (TSI) trends of an agricultural watershed with agricultural best management practices (BMPs) were assessed. Structural BMPs included vegetative buffers, conservation tillage, conservation reserve, a constructed wetland, and a sediment retention pond. TSI included Secchi visibility (SD), chlorophyll a (Chl), total phosphorus (TP), and total nitrogen (TN). Summer TSI 1977 was >80 in 1998–1999 (hypertrophic) and decreased over the first 10 years to TSI 1977 ≈ 75 (eutrophic). TSI 1977 decrease and changing TSI deviations coincided with vegetative buffers, conservation tillage, and conservation reserve. The TSI(SD) decrease (>90 to <70) coincided with vegetative buffers and TSI(TP) decrease (>90 to <75) coincided primarily with conservation tillage and the sediment retention pond. TSI(Chl) increase (<60 to >70) coincided with conservation tillage and vegetative buffer. Results indicate watershed-wide BMPs can modestly decrease summer trophic state through increased water transparency and decreased TP, but these changes are off-set by increases in chlorophyll a to reach a new stable state within a decade. Future research should assess algal nutrient thresholds, internal nutrient loading, and climate change effects. Full article

(This article belongs to the Special Issue Water Quality and Ecological Aspects of Aquatic Ecosystems Influenced by Agricultural Activity)

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26 pages, 14181 KiB

Open AccessFeature PaperArticle

Extreme Floods in the Eastern Part of Europe: Large-Scale Drivers and Associated Impacts

by Monica Ionita and Viorica Nagavciuc

Water 2021, 13(8), 1122; https://doi.org/10.3390/w13081122 - 19 Apr 2021

Cited by 19 | Viewed by 4174

Abstract

The role of the large-scale atmospheric circulation in producing heavy rainfall events and floods in the eastern part of Europe, with a special focus on the Siret and Prut catchment areas (Romania), is analyzed in this study. Moreover, a detailed analysis of the [...] Read more.

The role of the large-scale atmospheric circulation in producing heavy rainfall events and floods in the eastern part of Europe, with a special focus on the Siret and Prut catchment areas (Romania), is analyzed in this study. Moreover, a detailed analysis of the socio-economic impacts of the most extreme flood events (e.g., July 2008, June–July 2010, and June 2020) is given. Analysis of the largest flood events indicates that the flood peaks have been preceded up to 6 days in advance by intrusions of high Potential Vorticity (PV) anomalies toward the southeastern part of Europe, persistent cut-off lows over the analyzed region, and increased water vapor transport over the catchment areas of Siret and Prut Rivers. The vertically integrated water vapor transport prior to the flood peak exceeds 300 kg m⁻¹ s⁻¹, leading to heavy rainfall events. We also show that the implementation of the Flood Management Plan in Romania had positive results during the 2020 flood event compared with the other flood events, when the authorities took several precaution measurements that mitigated in a better way the socio-economic impact and risks of the flood event. The results presented in this study offer new insights regarding the importance of large-scale atmospheric circulation and water vapor transport as drivers of extreme flooding in the eastern part of Europe and could lead to a better flood forecast and flood risk management. Full article

(This article belongs to the Special Issue Management of Hydro-Meteorological Hazards)

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26 pages, 2608 KiB

Open AccessEditor’s ChoiceReview

Removal of Heavy Metals during Primary Treatment of Municipal Wastewater and Possibilities of Enhanced Removal: A Review

by Ida Sylwan and Eva Thorin

Water 2021, 13(8), 1121; https://doi.org/10.3390/w13081121 - 19 Apr 2021

Cited by 32 | Viewed by 6761

Abstract

Resource reuse has become an important aspect of wastewater management. At present, use of sludge in agriculture is one of the major reuse routes. Conventional municipal wastewater treatment does not involve any designated process for removal of heavy metals, and these distribute mainly [...] Read more.

Resource reuse has become an important aspect of wastewater management. At present, use of sludge in agriculture is one of the major reuse routes. Conventional municipal wastewater treatment does not involve any designated process for removal of heavy metals, and these distribute mainly between effluent and sludge. Enhanced removal of heavy metals during primary treatment may decrease the heavy metal concentrations in both effluent and sludge from secondary treatment and promote long-term reuse of secondary sludge. This review considers heavy metal occurrence and removal during primary settling, together with possible treatment technologies for heavy metal removal in primary settlers and their theoretical performance. The variation in total heavy metal concentrations and dissolved fraction in raw municipal wastewater points to a need for site-specific assessments of appropriate technologies for improved heavy metal removal. Studies examining the heavy metal speciation beyond dissolved/particulate are few. Missing or disparate information on process parameters such as hydraulic retention time, pH and composition of return flows makes it hard to generalize the findings from studies concerning heavy metal removal in primary settlers. Coagulation/flocculation and use of low-cost sorbents were identified as the most promising methods for enhancing heavy metal removal during primary settling. Based on the available data on heavy metal speciation and removal during primary settling, sorption technologies may be most effective for enhancing the removal of Cu and Ni, while coagulation may be efficient for Cd, Cr, Cu, Pb, Zn and Hg removal (but not as efficient for Ni removal). Full article

(This article belongs to the Special Issue Sustainable Processes for the Removing of Heavy Metals from Aqueous Solutions)

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22 pages, 5792 KiB

Open AccessArticle

Assessing the Hydroclimatic Movement under Future Scenarios Including both Climate and Land Use Changes

by Sinae Kim, Hakkwan Kim, Kyeung Kim, Sang-Min Jun, Soonho Hwang and Moon-Seong Kang

Water 2021, 13(8), 1120; https://doi.org/10.3390/w13081120 - 19 Apr 2021

Cited by 3 | Viewed by 2588

Abstract

In this study we simulated the watershed response according to future climate and land use change scenarios through a hydrological model and predicting future hydroclimate changes by applying the Budyko framework. Future climate change scenarios were derived from the UK Earth system model [...] Read more.

In this study we simulated the watershed response according to future climate and land use change scenarios through a hydrological model and predicting future hydroclimate changes by applying the Budyko framework. Future climate change scenarios were derived from the UK Earth system model (UKESM1), and future land use changes were predicted using the future land use simulation (FLUS) model. To understand the overall trend of hydroclimatic conditions, the movements in Budyko space were represented as wind rose plots. Moreover, the impacts of climate and land use changes were separated, and the watersheds’ hydroclimatic conditions were classified into five groups. In future scenarios, both increase and decrease of aridity index were observed depending on the watershed, and land use change generally led to a decrease in the evaporation index. The results indicate that as hydroclimatic movement groups are more diversely distributed by region in future periods, regional adaptation strategies could be required to reduce hydroclimatic changes in each region. The results derived from this study can be used as basic data to establish an appropriate water resource management plan and the governments’ land use plan. As an extension of this study, we can consider more diverse land use characteristics and other global climate model (GCMs) in future papers. Full article

(This article belongs to the Special Issue Climate Change Impacts on Hydrological Processes and Water Resources of Local Watersheds)

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15 pages, 3301 KiB

Open AccessFeature PaperArticle

Groundwater Nitrate Removal Performance of Selected Pseudomonas Strains Carrying nosZ Gene in Aerobic Granular Sequential Batch Reactors

by Miguel Hurtado-Martinez, Barbara Muñoz-Palazon, Alejandro Gonzalez-Martinez, Maximino Manzanera and Jesus Gonzalez-Lopez

Water 2021, 13(8), 1119; https://doi.org/10.3390/w13081119 - 19 Apr 2021

Cited by 10 | Viewed by 2658

Abstract

Four granular sequencing batch reactors (GSBRs) were inoculated with four denitrifying Pseudomonas strains carrying nosZ to study the process of granule formation, the operational conditions of the bioreactors, and the carbon concentration needed for nitrate removal. The selected Pseudomonas strains were P. stutzeri [...] Read more.

Four granular sequencing batch reactors (GSBRs) were inoculated with four denitrifying Pseudomonas strains carrying nosZ to study the process of granule formation, the operational conditions of the bioreactors, and the carbon concentration needed for nitrate removal. The selected Pseudomonas strains were P. stutzeri I1, P. fluorescens 376, P. denitrificans Z1, and P. fluorescens PSC26, previously reported as denitrifying microorganisms carrying the nosZ gene. Pseudomonas denitrificans Z1 produced fluffy, low-density granules, with a decantation speed below 10 m h⁻¹. However, P. fluorescens PSC26, P. stutzeri I1, and P. fluorescens 376 formed stable granules, with mean size from 7 to 15 mm, related to the strain and carbon concentration. P. stutzeri I1 and P. fluorescens 376 removed nitrate efficiently with a ratio in the range of 96%, depending on the source and concentration of organic matter. Therefore, the findings suggest that the inoculation of GSBR systems with denitrifying strains of Pseudomonas spp. containing the nosZ gene enables the formation of stable granules, the efficient removal of nitrate, and the transformation of nitrate into nitrogen gas, a result of considerable environmental interest to avoid the generation of nitrous oxide. Full article

(This article belongs to the Special Issue Biotechnology Applications in Water and Wastewater Treatment)

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23 pages, 8087 KiB

Open AccessArticle

Evaluation of Incipient Motion of Sand Particles by Different Indirect Methods in Erosion Function Apparatus

by Arif Jewel, Kazunori Fujisawa and Akira Murakami

Water 2021, 13(8), 1118; https://doi.org/10.3390/w13081118 - 19 Apr 2021

Cited by 1 | Viewed by 2694

Abstract

An experiment was carried out in an acrylic glass-sided re-circulating closed conduit with a rectangular cross section, which is similar in construction to an erosion function apparatus. An adjustable sand box, made of acrylic glass, was attached to the bottom of the conduit [...] Read more.

An experiment was carried out in an acrylic glass-sided re-circulating closed conduit with a rectangular cross section, which is similar in construction to an erosion function apparatus. An adjustable sand box, made of acrylic glass, was attached to the bottom of the conduit as the sand zone or the test section. The hydraulics of the flow in the erosion function apparatus is complicated due to the limited part of the non-smooth and erodible soil surface attached to the closed conduit. As the bed shear stress changes with the bed roughness, even though the flow velocity does not change, establishing a method to estimate the incipient motion is an important challenge for an erosion function apparatus. The present study was conducted to explore the incipient motion of sands from bed shear stress estimated by four different indirect methods on both the sand bed and the smooth bed installed in the erosion function apparatus. In the experiment, particle image velocimetry (PIV) was used to investigate flow dynamics and incipient motion in terms of dimensionless critical bed shear stress. The experimental results show that the bed shear stress estimated from the log-law profiles in the sand zone and the smooth zones are relatively higher than those of the other indirect methods. The dimensionless critical bed shear stress of threshold condition evaluated by all indirect methods was found in good agreement with those of previous results in both zones. The Manning roughness and Darcy–Weisbach friction coefficients were evaluated based on the critical shear velocity at the incipient motion. Although these coefficients were found slightly greater in the smooth zone than in the sand zone, in both zones, they showed good agreement with previous studies. Full article

(This article belongs to the Special Issue Sediment Transport and River Morphology)

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14 pages, 4216 KiB

Open AccessArticle

Microbial Detoxification of Dimethoate and Methomyl Residues in Aqueous Media

by Aly Derbalah, Ahmed Massoud, Ibrahim El-Mehasseb, Moustafa Saad Allah, Mohamed S. Ahmed, Ashraf Al-Brakati and Ehab Kotb Elmahallawy

Water 2021, 13(8), 1117; https://doi.org/10.3390/w13081117 - 19 Apr 2021

Cited by 10 | Viewed by 2652

Abstract

The extensive and random application of major organic pollutants, mainly pesticides, threatens ecosystems and human health. The present study was conducted to isolate and identify microorganisms from some water resources contaminated with pesticides. We investigated the ability of the identified microbes to grow [...] Read more.

The extensive and random application of major organic pollutants, mainly pesticides, threatens ecosystems and human health. The present study was conducted to isolate and identify microorganisms from some water resources contaminated with pesticides. We investigated the ability of the identified microbes to grow in water spiked with dimethoate and methomyl. We also evaluated the potential effect of the identified microbial isolates on dimethoate and methomyl biodegradation in water. In addition, the total detoxification of dimethoate and methomyl residues in water after treatment with the most effective microbial isolates was confirmed using toxicity tests and analyzing biochemical parameters and histopathological changes in the kidney and liver of treated rats. The microbial isolates were identified as Xanthomonas campestris pv. Translucens and Aspergillus fumigates. Results showed that X. campestris pv. Translucens and A. fumigatus grow in media supplemented with dimethoate and methomyl faster than in other media without both pesticides. About 97.8% and 91.2% of dimethoate and 95% and 87.8% of methomyl (initial concentration of both 5 mg L⁻¹) were biodegraded within 32 days of incubation with X. campestris pv. Translucens and A. fumigatus, respectively. There was no remaining toxicity in rats treated with dimethoate- and methomyl-contaminated water with respect to biochemical parameters and histopathological changes. Collectively, the identified bacterial isolate showed high potential for the complete degradation of dimethoate and methomyl residues in water. Full article

(This article belongs to the Special Issue Microbial Communities in Water Environments: Dynamics and Interaction)

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18 pages, 4728 KiB

Open AccessArticle

Sensitivity Analysis for Performance Evaluation of a Real Water Distribution System by a Pressure Driven Analysis Approach and Artificial Intelligence Method

by Attilio Fiorini Morosini, Sina Shaffiee Haghshenas, Sami Shaffiee Haghshenas, Doo Yong Choi and Zong Woo Geem

Water 2021, 13(8), 1116; https://doi.org/10.3390/w13081116 - 18 Apr 2021

Cited by 19 | Viewed by 2796

Abstract

Proper performance of water distribution networks (WDNs) plays a vital role in customer satisfaction. The aim of this study is to conduct a sensitivity analysis to evaluate the behavior of WDNs analyzed by a pressure-driven analysis (PDA) approach and the classification technique by [...] Read more.

Proper performance of water distribution networks (WDNs) plays a vital role in customer satisfaction. The aim of this study is to conduct a sensitivity analysis to evaluate the behavior of WDNs analyzed by a pressure-driven analysis (PDA) approach and the classification technique by using an appropriate artificial neural network, namely the Group Method of Data Handling (GMDH). For this purpose, this study is divided into four distinct steps. In the first and second steps, a real network has been analyzed by using a Pressure-Driven Analysis approach (PDA) to obtain the pressure, and α coefficient, the percentage of supplied flow. The analysis has been performed by using three different values of the design peak coefficient k*. In the third step, the Group Method of Data Handling (GMDH) has been applied and several binary models have been constructed. The analysis has been carried out by using input data, including the real topology of the network and the base demand necessary to satisfy requests of users in average conditions and by assuming that the demand in each single one-hour time step depends on a peak coefficient. Finally, the results obtained from the PDA hydraulic analysis and those obtained by using them in the GMDH algorithm have been compared and sensitivity analysis has been carried out. The innovation of the study is to demonstrate that the input parameters adopted in the design are correct. The analysis confirms that the GMDH algorithm gives proper results for this case study and the results are stable also when the value of each k*, characteristic of a different time hour step, varies in an admissible technical range. It was confirmed that the results obtained by using the PDA approach, analyzed by using a GMDH-type neural network, can provide higher performance sufficiency in the evaluation of WDNs. Full article

(This article belongs to the Special Issue Innovative Approaches in the Optimization of Water Distribution Networks)

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12 pages, 8581 KiB

Open AccessArticle

Genetic Diversity of Stellate Sturgeon in the Lower Danube River: The Impact of Habitat Contraction upon a Critically Endangered Population

by Daniela Nicoleta Holostenco, Mitică Ciorpac, Elena Taflan, Katarina Tošić, Marian Paraschiv, Marian Iani, Ștefan Honț, Radu Suciu and Geta Rîșnoveanu

Water 2021, 13(8), 1115; https://doi.org/10.3390/w13081115 - 18 Apr 2021

Cited by 4 | Viewed by 2379

Abstract

One of the last wild populations of the critically endangered stellate sturgeon (Acipenser stellatus) survives in the Danube River. Limited knowledge about the genetic structure, ecology, and evolution of this species led to poor and inconsistent management decisions with an increased [...] Read more.

One of the last wild populations of the critically endangered stellate sturgeon (Acipenser stellatus) survives in the Danube River. Limited knowledge about the genetic structure, ecology, and evolution of this species led to poor and inconsistent management decisions with an increased risk for species extinction in the wild. Here we show the results of genetic structure screening of the Danube River wild population over 12 years timespan. Our research does not bring evidence of population recovery. No genetic structuring was identified at the mitochondrial level concerning spawning migration timing, sampling locations, and developmental stages. Eleven maternal lineages were revealed based on restriction fragment lengths analysis of the D-loop region, with one haplotype as the most frequent. While this could be the result of a massive restocking activity using a reduced number of spawners, our data does not support it. The selection of mitochondrial haplotypes under the pressure of habitat contraction and the narrower range of temperature variation since dams’ construction on the river could explain the observed distribution. Several factors of managerial concern are discussed. Our results provide baseline data on the mtDNA diversity in a critically endangered species of exceptionally high socioeconomic and conservation interest. Full article

(This article belongs to the Special Issue Biodiversity Conservation and Ecosystem Management in Fresh and Transitional Waters)

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18 pages, 1983 KiB

Open AccessArticle

Social Dimensions of Projected Climate Change Impacts on Ecosystem Services in the Coastal-Rural Area of Nemunas River Reaches and Curonian Lagoon (Lithuania)

by Lina Marcinkevičiūtė, Jolanta Vilkevičiūtė, Jan Žukovskis and Rasa Pranskūnienė

Water 2021, 13(8), 1114; https://doi.org/10.3390/w13081114 - 18 Apr 2021

Cited by 3 | Viewed by 2905

Abstract

The capacity of ecosystems to provide ecosystem services (hereinafter referred to as ES) depends on the state of their structure, processes, and functions, which is determined by interactions with other systems. These interactions are complex and take place in different climatic areas, and [...] Read more.

The capacity of ecosystems to provide ecosystem services (hereinafter referred to as ES) depends on the state of their structure, processes, and functions, which is determined by interactions with other systems. These interactions are complex and take place in different climatic areas, and have different impacts on ecosystems and the use of ES. As the most sensitive part of the Lithuanian shore zone to climate change is the seaside zone or the coastal zone, which includes the Curonian Lagoon and the sea coast, the said area was therefore chosen for research. The case study examined those ES that were specific to the study area, without attempting to account for absolutely all ES. With an emphasis on the representation of different perspectives (in the process of assessing and preserving the potential of ES), the empirical study involved representatives of different (public and private) sectors. The public sector was represented by elders and eldership employees, the private sector by farmers and businesspeople. Respondents were selected purposefully to reflect the entire existing totality of the existing area. The evaluation of the obtained theoretical and practical results of the research identified the potential of the existing area ecosystem services and perspectives for the implementation of services by assessing their use according to respondents’ opinions, regional climate change, and national scale in EU environmental policy. Full article

(This article belongs to the Special Issue Management and Monitoring of Urban and Rural Ecological Water Resources)

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24 pages, 1159 KiB

Open AccessFeature PaperReview

Towards the Optimization of eDNA/eRNA Sampling Technologies for Marine Biosecurity Surveillance

by Holly A. Bowers, Xavier Pochon, Ulla von Ammon, Neil Gemmell, Jo-Ann L. Stanton, Gert-Jan Jeunen, Craig D. H. Sherman and Anastasija Zaiko

Water 2021, 13(8), 1113; https://doi.org/10.3390/w13081113 - 18 Apr 2021

Cited by 43 | Viewed by 10448

Abstract

The field of eDNA is growing exponentially in response to the need for detecting rare and invasive species for management and conservation decisions. Developing technologies and standard protocols within the biosecurity sector must address myriad challenges associated with marine environments, including salinity, temperature, [...] Read more.

The field of eDNA is growing exponentially in response to the need for detecting rare and invasive species for management and conservation decisions. Developing technologies and standard protocols within the biosecurity sector must address myriad challenges associated with marine environments, including salinity, temperature, advective and deposition processes, hydrochemistry and pH, and contaminating agents. These approaches must also provide a robust framework that meets the need for biosecurity management decisions regarding threats to human health, environmental resources, and economic interests, especially in areas with limited clean-laboratory resources and experienced personnel. This contribution aims to facilitate dialogue and innovation within this sector by reviewing current approaches for sample collection, post-sampling capture and concentration of eDNA, preservation, and extraction, all through a biosecurity monitoring lens. Full article

(This article belongs to the Special Issue Applications of Environmental DNA and RNA in Aquatic Ecosystems)

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19 pages, 2457 KiB

Open AccessEditor’s ChoiceArticle

Evaluating the Collaborative Security of Water–Energy–Food in China on the Basis of Symbiotic System Theory

by Xiao Li, Cuishan Liu, Guoqing Wang, Zhenxin Bao, Yanfang Diao and Jing Liu

Water 2021, 13(8), 1112; https://doi.org/10.3390/w13081112 - 17 Apr 2021

Cited by 9 | Viewed by 2562

Abstract

Water, energy, and food are essential resources for humanity. The growing shortages of these resources and serious deterioration of river environments are having a big impact on the sustainable development of the economy and society in China. Water, energy, and food support human [...] Read more.

Water, energy, and food are essential resources for humanity. The growing shortages of these resources and serious deterioration of river environments are having a big impact on the sustainable development of the economy and society in China. Water, energy, and food support human life and yet coexist in different ways, and therefore it is critical to find a way for all three key elements to be secured in order to support high standards of sustainable development in China. We used the criteria of stability, coordination, and sustainability of symbiotic systems to select 33 indexes that were then used to establish an index system. The weight of index was determined by using the entropy weight method combined with Analytic Hierarchy Process. The fuzzy comprehensive evaluation method was used to calculate the collaborative security index, which was the basis of our evaluation of the collaborative water–energy–food security of China in time and space. The results show that North China and Northwest China are at high water–food–energy security risk, while East, Central, and South China are at moderate risk. With the exception of Southwest China and South China, risk in most parts of the country has risen over the past decades, while it has fallen in Shandong, Henan, Sichuan, and Yunnan provinces. Full article

(This article belongs to the Special Issue The Water-Energy-Food Nexus: Sustainable Development)

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21 pages, 7077 KiB

Open AccessArticle

Selecting Suitable MODFLOW Packages to Model Pond–Groundwater Relations Using a Regional Model

by Carmen Serrano-Hidalgo, Carolina Guardiola-Albert, Javier Heredia, Francisco Javier Elorza Tenreiro and Nuria Naranjo-Fernández

Water 2021, 13(8), 1111; https://doi.org/10.3390/w13081111 - 17 Apr 2021

Cited by 6 | Viewed by 3859

Abstract

In large-scale regional models, used for the management of underground resources, it is quite common to find that relationships between the regional aquifer and small wetlands are not included. These models do not consider this connection because of the small amount of water [...] Read more.

In large-scale regional models, used for the management of underground resources, it is quite common to find that relationships between the regional aquifer and small wetlands are not included. These models do not consider this connection because of the small amount of water involved, but they should consider the potential for significant ecological impacts if the groundwater resources in the ecosystems associated with these wetlands are mismanaged. The main objective of this work is to investigate the possibilities offered by MODFLOW LGR-V2 to represent (at small scale) the Santa Olalla pond, located in the Doñana Natural Park (South of Spain), and its relationship with the Almonte-Marismas regional aquifer. As a secondary objective, we propose to investigate the advantages and disadvantages that DRAIN, RIVER and LAKE MODFLOW packages offer within the MODFLOW LGR-V2 discretizations. The drain boundary condition with a coarse discretization implemented through ModelMuse allows the most adequate performance of the groundwater levels in the environment of the pond. However, when using lake boundary condition, the use of the MODFLOW LGR-V2 version is particularly useful. The present work also gives some guidelines to employ these packages with the MODFLOW graphical user’s interface, ModelMuse 4.2. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

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13 pages, 317 KiB

Open AccessFeature PaperReview

Coliphages as a Complementary Tool to Improve the Management of Urban Wastewater Treatments and Minimize Health Risks in Receiving Waters

by Juan Jofre, Francisco Lucena and Anicet R. Blanch

Water 2021, 13(8), 1110; https://doi.org/10.3390/w13081110 - 17 Apr 2021

Cited by 11 | Viewed by 3603

Abstract

Even in countries with extensive sanitation systems, outbreaks of waterborne infectious diseases are being reported. Current tendencies, such as the growing concentration of populations in large urban conurbations, climate change, aging of existing infrastructures, and emerging pathogens, indicate that the management of water [...] Read more.

Even in countries with extensive sanitation systems, outbreaks of waterborne infectious diseases are being reported. Current tendencies, such as the growing concentration of populations in large urban conurbations, climate change, aging of existing infrastructures, and emerging pathogens, indicate that the management of water resources will become increasingly challenging in the near future. In this context, there is an urgent need to control the fate of fecal microorganisms in wastewater to avoid the negative health consequences of releasing treated effluents into surface waters (rivers, lakes, etc.) or marine coastal water. On the other hand, the measurement of bacterial indicators yields insufficient information to gauge the human health risk associated with viral infections. It would therefore seem advisable to include a viral indicator—for example, somatic coliphages—to monitor the functioning of wastewater treatments. As indicated in the studies reviewed herein, the concentrations of somatic coliphages in raw sewage remain consistently high throughout the year worldwide, as occurs with bacterial indicators. The removal process for bacterial indicators and coliphages in traditional sewage treatments is similar, the concentrations in secondary effluents remaining sufficiently high for enumeration, without the need for cumbersome and costly concentration procedures. Additionally, according to the available data on indicator behavior, which is still limited for sewers but abundant for surface waters, coliphages persist longer than bacterial indicators once outside the gut. Based on these data, coliphages can be recommended as indicators to assess the efficiency of wastewater management procedures with the aim of minimizing the health impact of urban wastewater release in surface waters. Full article

(This article belongs to the Special Issue Dynamic and Diversity of Waterborne Pathogens and Fecal Indicators in Urban Surface Waters)

14 pages, 4183 KiB

Open AccessArticle

Surface Water Temperature Predictions at a Mid-Latitude Reservoir under Long-Term Climate Change Impacts Using a Deep Neural Network Coupled with a Transfer Learning Approach

by Nobuaki Kimura, Kei Ishida and Daichi Baba

Water 2021, 13(8), 1109; https://doi.org/10.3390/w13081109 - 17 Apr 2021

Cited by 4 | Viewed by 2608

Abstract

Long-term climate change may strongly affect the aquatic environment in mid-latitude water resources. In particular, it can be demonstrated that temporal variations in surface water temperature in a reservoir have strong responses to air temperature. We adopted deep neural networks (DNNs) to understand [...] Read more.

Long-term climate change may strongly affect the aquatic environment in mid-latitude water resources. In particular, it can be demonstrated that temporal variations in surface water temperature in a reservoir have strong responses to air temperature. We adopted deep neural networks (DNNs) to understand the long-term relationships between air temperature and surface water temperature, because DNNs can easily deal with nonlinear data, including uncertainties, that are obtained in complicated climate and aquatic systems. In general, DNNs cannot appropriately predict unexperienced data (i.e., out-of-range training data), such as future water temperature. To improve this limitation, our idea is to introduce a transfer learning (TL) approach. The observed data were used to train a DNN-based model. Continuous data (i.e., air temperature) ranging over 150 years to pre-training to climate change, which were obtained from climate models and include a downscaling model, were used to predict past and future surface water temperatures in the reservoir. The results showed that the DNN-based model with the TL approach was able to approximately predict based on the difference between past and future air temperatures. The model suggested that the occurrences in the highest water temperature increased, and the occurrences in the lowest water temperature decreased in the future predictions. Full article

(This article belongs to the Special Issue Machine Learning for Hydro-Systems)

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18 pages, 908 KiB

Open AccessArticle

Influence of the Evolution of Marine Industry Structure on the Green Total Factor Productivity of Marine Economy

by Xinyi Wei, Qiuguang Hu, Weiteng Shen and Jintao Ma

Water 2021, 13(8), 1108; https://doi.org/10.3390/w13081108 - 17 Apr 2021

Cited by 25 | Viewed by 2991

Abstract

The 14th five-year plan emphasizes the importance of marine ecology and environmental protection, and the green concept is incorporated into the high-quality development system of the marine economy. This research used the data of 11 coastal provinces and cities in China from 2006 [...] Read more.

The 14th five-year plan emphasizes the importance of marine ecology and environmental protection, and the green concept is incorporated into the high-quality development system of the marine economy. This research used the data of 11 coastal provinces and cities in China from 2006 to 2016, based on the super-efficiency slack-based measure model and global Malmquist index model. The objective was to calculate the green total factor productivity (GTFP) of the marine economy, to study the impact of the evolution of the marine industrial structure on marine economic GTFP. The study found the following: (1) in general, the upgrade of marine industrial structure promoted the growth of marine economic GTFP and presented an inverted “U” trend of initially promoting and then suppressing. Spatially, only the advancement and rationalization of industrial structure in the Yellow and Bohai Sea regions inhibited the growth of marine economic GTFP. In terms of time, the advanced marine industrial structure promoted the growth of GTFP from 2006 to 2010, whereas that of industrial structure inhibited the growth of GTFP from 2011 to 2016. (2) The GTFP of the marine economy showed an increasing trend, but the conversion rate of production technology is low. Falling into the “efficiency trap” of highly advanced technology input and low-efficiency technology output should be avoided. (3) Affected by the mismatch of regional resources or industrial structure, government intervention showed an “opposite” mechanism in areas with different marine economic strengths. Government intervention in areas with higher marine economic strength was conducive to GTFP growth, whereas government intervention in areas with weaker marine economic strength would hinder GTFP growth. Full article

(This article belongs to the Special Issue The Blue Economy: Evaluating the Human Benefits from and Pressures on Marine and Coastal Environments)

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17 pages, 3170 KiB

Open AccessArticle

Analytical Models of Velocity, Reynolds Stress and Turbulence Intensity in Ice-Covered Channels

by Jiao Zhang, Wen Wang, Zhanbin Li, Qian Li, Ya Zhong, Zhaohui Xia and Hunan Qiu

Water 2021, 13(8), 1107; https://doi.org/10.3390/w13081107 - 17 Apr 2021

Cited by 2 | Viewed by 2116

Abstract

Ice cover in an open channel can influence the flow structure, such as the flow velocity, Reynolds stress and turbulence intensity. This study analyzes the vertical distributions of velocity, Reynolds stress and turbulence intensity in fully and partially ice-covered channels by theoretical methods [...] Read more.

Ice cover in an open channel can influence the flow structure, such as the flow velocity, Reynolds stress and turbulence intensity. This study analyzes the vertical distributions of velocity, Reynolds stress and turbulence intensity in fully and partially ice-covered channels by theoretical methods and laboratory experiments. According to the experimental data, the vertical profile of longitudinal velocities follows an approximately symmetry form. Different from the open channel flow, the maximum value of longitudinal velocity occurs near the middle of the water depth, which is close to the channel bed with a smoother boundary roughness compared to the ice cover. The measured Reynolds stress has a linear distribution along the vertical axis, and the vertical distribution of measured turbulence intensity follows an exponential law. Theoretically, a two-power-law function is presented to obtain the analytical formula of the longitudinal velocity. In addition, the vertical profile of Reynolds stress is obtained by the simplified momentum equation and the vertical profile of turbulence intensity is investigated by an improved exponential model. The predicted data from the analytical models agree well with the experimental ones, thereby confirming that the analytical models are feasible to predict the vertical distribution of velocity, Reynolds stress and turbulence intensity in ice-covered channels. The proposed models can offer an important theoretical reference for future study about the sediment transport and contaminant dispersion in ice-covered channels. Full article

(This article belongs to the Special Issue Fluvial Hydraulics Affected by River Ice and Hydraulic Structures)

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25 pages, 10293 KiB

Open AccessArticle

‘Hidden Hot Springs’ as a Source of Groundwater Fluoride and Severe Dental Fluorosis in Malawi

by Marc J. Addison, Michael O. Rivett, Owen L. Phiri, Nigel Milne, Vicky Milne, Alex D. McMahon, Lorna M. D. Macpherson, Jeremy Bagg, David I. Conway, Peaches Phiri, Emma Mbalame, Innocent Manda and Robert M. Kalin

Water 2021, 13(8), 1106; https://doi.org/10.3390/w13081106 - 17 Apr 2021

Cited by 8 | Viewed by 4820

Abstract

Hidden hot springs likely impact rural water supplies in Malawi’s Rift Valley with excess dissolved fluoride leading to localised endemic severe dental fluorosis. Predicting their occurrence is a challenge; Malawi’s groundwater data archive is sporadic and incomplete which prevents the application of standard [...] Read more.

Hidden hot springs likely impact rural water supplies in Malawi’s Rift Valley with excess dissolved fluoride leading to localised endemic severe dental fluorosis. Predicting their occurrence is a challenge; Malawi’s groundwater data archive is sporadic and incomplete which prevents the application of standard modelling techniques. A creative alternative method to predict hidden hot spring locations was developed using a synthesis of proxy indicators (geological, geochemical, dental) and is shown to be at least 75% effective. An exciting collaboration between geoscientists and dentists allowed corroboration of severe dental fluorosis with hydrogeological vulnerability. Thirteen hidden hot springs were identified based on synthesised proxy indicators. A vulnerability prediction map for the region was developed and is the first of its kind in Malawi. It allows improved groundwater fluoride prediction in Malawi’s rift basin which hosts the majority of hot springs. Moreover, it allows dentists to recognise geological control over community oral health. Collaborative efforts have proven mutually beneficial, allowing both disciplines to conduct targeted research to improve community wellbeing and health and inform policy development in their respective areas. This work contributes globally in developing nations where incomplete groundwater data and vulnerability to groundwater contamination from hydrothermal fluoride exist in tandem. Full article

(This article belongs to the Special Issue Groundwater Vulnerability to Pollution Assessment)

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17 pages, 3933 KiB

Open AccessArticle

Land Use and Land Cover Change Assessment in the Context of Flood Hazard in Lagos State, Nigeria

by Dorcas Idowu and Wendy Zhou

Water 2021, 13(8), 1105; https://doi.org/10.3390/w13081105 - 17 Apr 2021

Cited by 9 | Viewed by 6468

Abstract

Incessant flooding is a major hazard in Lagos State, Nigeria, occurring concurrently with increased urbanization and urban expansion rate. Consequently, there is a need for an assessment of Land Use and Land Cover (LULC) changes over time in the context of flood hazard [...] Read more.

Incessant flooding is a major hazard in Lagos State, Nigeria, occurring concurrently with increased urbanization and urban expansion rate. Consequently, there is a need for an assessment of Land Use and Land Cover (LULC) changes over time in the context of flood hazard mapping to evaluate the possible causes of flood increment in the State. Four major land cover types (water, wetland, vegetation, and developed) were mapped and analyzed over 35 years in the study area. We introduced a map-matrix-based, post-classification LULC change detection method to estimate multi-year land cover changes between 1986 and 2000, 2000 and 2016, 2016 and 2020, and 1986 and 2020. Seven criteria were identified as potential causative factors responsible for the increasing flood hazards in the study area. Their weights were estimated using a combined (hybrid) Analytical Hierarchy Process (AHP) and Shannon Entropy weighting method. The resulting flood hazard categories were very high, high, moderate, low, and very low hazard levels. Analysis of the LULC change in the context of flood hazard suggests that most changes in LULC result in the conversion of wetland areas into developed areas and unplanned development in very high to moderate flood hazard zones. There was a 69% decrease in wetland and 94% increase in the developed area during the 35 years. While wetland was a primary land cover type in 1986, it became the least land cover type in 2020. These LULC changes could be responsible for the rise in flooding in the State. Full article

(This article belongs to the Section Hydrology)

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14 pages, 271 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Water ‘Apartheid’ and the Significance of Human Rights Principles of Affirmative Action in South Africa

by Ademola Oluborode Jegede and Pumzile Shikwambane

Water 2021, 13(8), 1104; https://doi.org/10.3390/w13081104 - 16 Apr 2021

Cited by 10 | Viewed by 6757

Abstract

Water is an essential necessity for human beings; however, South Africa has a long history of inequalities dating back to apartheid politics and legislation which denied access to water to disadvantaged black populations mostly residing in rural areas. Although apartheid has officially ended, [...] Read more.

Water is an essential necessity for human beings; however, South Africa has a long history of inequalities dating back to apartheid politics and legislation which denied access to water to disadvantaged black populations mostly residing in rural areas. Although apartheid has officially ended, whether the lack of access to water by such populations who still cannot afford it exists and aligns with international human rights principles of equality and non-discrimination merits an examination. To redress the injustices of the apartheid regime, the right to have access to sufficient water is entrenched in section 27(1)(b) of the 1996 South African Constitution. In addition to embracing equality and non-discrimination, the Constitution informs other instruments and measures such as free basic water policy and pre-paid meters meant to ensure access to water. However, the plight of these populations persists in post-apartheid South Africa, but it is rarely a subject of academic scrutiny how the notion of affirmative action as grounded in the principles of equality and non-discrimination under human rights law can be deployed as a response. Using a doctrinal research approach, this article argues that the continuing struggle of disadvantaged communities with access to water does not only constitute water apartheid, it negates the human rights principles of equality and non-discrimination. The principle of affirmative action is useful in responding to inadequate access to sufficient water by disadvantaged populations in post-apartheid South Africa. Full article

(This article belongs to the Special Issue The Politics of the Human Right to Water)

14 pages, 4620 KiB

Open AccessArticle

Identification Sources and High-Risk Areas of Sediment Heavy Metals in the Yellow River by Geographical Detector Method

by Jianxiu Hao, Jun Ren, Hongbing Fang and Ling Tao

Water 2021, 13(8), 1103; https://doi.org/10.3390/w13081103 - 16 Apr 2021

Cited by 9 | Viewed by 2651

Abstract

In order to determine the key influencing factors, risk areas, and source pathways of heavy metals in the sediment of the Yellow River, 37 samples were collected in the surface sediment (0–5 cm) of the Inner Mongolia section of the Yellow River main [...] Read more.

In order to determine the key influencing factors, risk areas, and source pathways of heavy metals in the sediment of the Yellow River, 37 samples were collected in the surface sediment (0–5 cm) of the Inner Mongolia section of the Yellow River main stream for the determination of heavy metals copper (Cu), nickel (Ni), zinc (Zn), chromium (Cr), lead (Pb), and cadmium (Cd). Based on the geographical detector model (GDM) and ArcGIS 10.2 software, this paper selected 6 heavy metals and 15 influencing factors, including 8 natural factors and 7 anthropogenic factors, to detect key influencing factors, risk areas, and sources of heavy metals. The results showed that: (1) The average contents of heavy metals Cr and Cd in the sediments exceeded the average value in soil, the world average concentration in the shales, and the first-level standard of soil environmental quality in China, and they were the main risk metals; (2) Vegetation coverage (VC) was the largest influencing factor for the spatial distribution of heavy metals in the sediment, followed by per capita income (PI), and land use type (LUT) and road network density (RD) were smaller influencing factors. The interactions of the factors were enhanced; (3) The Wuhai section for a risk area was mainly polluted by Cd and Pb, which were caused by atmospheric deposition and industrial emission. The Baotou section for a risk area was mainly polluted by Cr, which mainly originated from river transportation and industrial discharge. The conclusions can provide a scientific basis for the environmental protection and management of the different areas in the Inner Mongolia section of the Yellow River. Full article

(This article belongs to the Section Water Erosion and Sediment Transport)

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