Refine search
Results 5771-5780 of 6,560
Seasonal water quality index and suitability of the water body to designated uses at the eastern catchment of Lake Hawassa Full text
2020
Teshome, Fiseha Bekele
The availability of quality water is imperative to human health and ecosystem functioning. This study was aimed at determining the water quality index and examining its suitability to different water uses. Water samples were collected in dry and rainy seasons to capture the influence of seasonal variation. Water quality indicators (pH, electric conductivity (EC), temperature, total dissolved solids (TDS), turbidity, total suspended solids (TSS), nitrate, phosphate, and ammonia) were analyzed in the laboratory, and weighted arithmetic index method was employed to determine the quality index. The water quality index (WQI) showed higher value 870.3 and 1,313 for dry and rainy seasons which indicates that the water is unfit for human use, and the status of the water body is hypereutrophic. With cautions handling, the water appeared to be suitable for irrigation and livestock production but undesirable for aquatic life and resulted in an impairment of the ecosystem. The statistical analysis revealed a significant difference in water quality parameters between dry and rainy seasons (p < 0.05). The overall water quality status demonstrated concerns that could pose a significant risk; hence, measures should be taken to improve the quality and manage water to safeguard human health and environmental safety.
Show more [+] Less [-]Mitigating biofouling with a vanillin coating on thin film composite reverse osmosis membranes Full text
2020
Shin, Hyunseo | Park, Chansoo | Lee, Chang Kyu | Lee, Yong-Soo | Kim, Jong-Oh
Several methods, such as pretreatment, membrane surface modification, feed water chlorination, and chemical cleaning, have recently been applied to control biofouling on reverse osmosis (RO) membranes—with limited success. As an alternative, compounds that inhibit bacterial quorum sensing can be used to disrupt formation of bacterial colonies. In this study, anti-biofouling using vanillin, which is a natural substance among quorum sensing inhibitor compounds, was trialed, by modifying RO membrane surfaces with vanillin, at various concentrations. We then reviewed consequential changes to membrane surface characteristics and vanillin anti-biofouling properties. A long-term RO membrane simulator was used to analyze permeability, contact angle was measured for hydrophilicity evaluation, and membrane surface morphology was analyzed, through atomic force microscopy and scanning electron microscopy. A quorum quenching effect was confirmed by utilizing Petrifilm to count bacteria on the surface of a modified membrane. As a result, the permeability of the surface modified membranes was slightly decreased compared to the pristine membrane, but the hydrophilicity was increased, and the number of colonies decreased remarkably, the membrane modified with 0.5 M vanillin outperforming that modified with 0.25 M vanillin.
Show more [+] Less [-]Household energy choice for domestic cooking: distribution and factors influencing cooking fuel preference in Ouagadougou Full text
2020
Sana, Adama | Kafando, Benoit | Dramaix, Michèle | Meda, Nicolas | Bouland, Catherine
Many studies have highlighted the link between indoor air pollution from the burning of solid fuels for cooking and heating and the occurrence of various health problems particularly in women and children under 5 years. In developing countries, solid fuels remain the main sources of energy. The purpose of this study aims to describe the distribution of household cooking fuel types and to analyze the factors influencing household cooking energy choice in Ouagadougou. A cross-sectional survey was conducted in 2017 in 3 neighborhoods of Ouagadougou. A total of 1734 household were randomly selected. We performed a multivariable logistic regression and a multinomial logistic regression to measure the relationship between selected determinants and households’ primary cooking fuel. 59.53% of the households of Ouagadougou reported using solid fuels as the main cooking fuel. Wood is the most common primary cooking fuel used (43.93%), followed by LPG (40.41%) and then charcoal (15.60%). About 84% combine at least 2 types of energy for cooking. Cooking fuel choice is strongly influenced by the socioeconomic status, the family size, and also by the woman’s educational attainment, her age and the main cooking fuel used in her parents’ house. Actions aimed at reducing the impact of solid fuel use in the environment or health must consider these factors.
Show more [+] Less [-]CR(VI) phytoremediation by hairy roots of Brassica napus: assessing efficiency, mechanisms involved, and post-removal toxicity Full text
2020
Perotti, Romina | Paisio, Cintia Elizabeth | Agostini, Elizabeth | Fernández, María Inés | González, Paola Solange
Industrial activities such as leather tanning involve the use of highly toxic inorganic pollutants, like Chromium (Cr). This work evaluated Cr(VI) remediation by hairy roots (HR) of Brassica napus, paying close attention to the mechanisms involved and the toxicity of post-removal solutions. Results showed that these roots were capable of tolerating concentrations of up to 10 mg L⁻¹ Cr(VI), while higher concentrations were toxic for HR development. Removal efficiency was assessed through the use of synthetic solutions containing different initial Cr(VI) concentrations (2, 5, or 10 mg L⁻¹). Regardless of these initial concentrations, the highest removal efficiency values were between 80 and 90% after 24 and 48 h of treatment, using a 2.0 g inoculum. The mechanisms involved were Cr accumulation (60%) and to a lesser extent, adsorption to the root biomass (30%). A fraction of Cr(VI) was intracellularly reduced to Cr(III), which suggests reductases may have played a role. Additionally, post-removal toxicity was evaluated through two bioassays (Lactuca sativa L. and AMPHITOX test) after the removal of 10 mg L⁻¹ Cr(VI). The treated solutions showed moderate phytotoxicity for L. sativa L. and no toxicity for R arenarum. The ability of HR to remove 10 mg L⁻¹ Cr(VI) from real tannery effluents collected from a regional industry (Córdoba province, Argentina) was also determined. The high removal efficiency observed (98%) demonstrates this system can be successful in treating complex wastewaters.
Show more [+] Less [-]Neurological effects of subchronic exposure to dioctyl phthalate (DOP), lead, and arsenic, individual and mixtures, in immature mice Full text
2020
Feng, Weiwei | Wu, Xueshan | Mao, Guanghua | Zhao, Ting | Wang, Wei | Chen, Yao | Zhang, Min | Yang, Liuqing | Wu, Xiangyang
Dioctyl phthalate (DOP) (200, 500, and 1000 mg kg⁻¹ bw, i.g.), Pb (Ac)₂ (50 mg L⁻¹, p.o.), and NaAsO₂ (10 mg L⁻¹, p.o.) were administered individually and as mixtures to weanling male mice for 8 weeks. It was observed that Pb, As, and DOP exposure could significantly inhibit the growth and development of mice. Compared with the Pb, As, and Pb + As groups, the activities of iNOS and TNOS were significantly increased, the levels of AChE and SOD were significantly decreased, and the level of MDA was significantly increased in the Pb + DOP-H, As + DOP-H, and Pb + As + DOP-H groups. The factorial analysis shows that the iNOS, TNOS, and AChE present synergistic effects on Pb, As, and DOP. A significant increase of escape latency and a significant decrease of original platform quadrant stops were observed between Pb + As + DOP-H and Pb + As groups. The factorial analysis shows that there was a synergistic effect on Pb, As, and DOP. Compared with that of the control group, the expression levels of caspase-3 and Bax expression in Pb + As, DOP-H, Pb + DOP-H, As + DOP-H, and Pb + As + DOP-H groups were significantly increased in the hippocampus. The expression levels of Bcl-2 expression decreased significantly and the Bax/Bcl-2 ratio increased significantly. Pathological alterations on the hippocampus were found in exposed groups. This result shows that combined exposure of Pb, As, and DOP could induce neurotoxicity, of which possible mechanism is hippocampal neuronal apoptosis. Graphical abstract This study shows that there were three components with eigenvalues greater than 1, which together explained 89.40% of total variance. The first component (PC1) showed high loadings on B-SOD, L-SOD, B-MDA, L-MDA, K-MDA, iNOS, tNOS, and AChE and accounted for 46.55% of the total variance after Varimax rotation. PC2 accounted for 23.81% of the total variance with high loadings on B-As, L-As, K-As, and K-SOD, whereas PC3 showed high loadings on B-Pb, L-Pb, and K-Pb and accounted for 19.04% of the total variance.
Show more [+] Less [-]Biota sediment accumulation and bioconcentration factors of trace metals in the snail Melanoides tuberculata form the agricultural drains of the Manzala Lagoon, Egypt Full text
2020
Orabi, Orabi | Khalifa, Moataz M.
The freshwater mollusk, Melanoides tuberculata, contains bioconcentration trace metals in its tissues from the surrounding area. M. tuberculata was used as a bioindicator for pollution with seven trace metals (Mn, Fe, Ni, Cu, Zn, Cd, and Pb) accumulated in snail soft tissues near Bahr El-Baqar and El-Serw agricultural drains of industrial activities in Port Said and Damietta, respectively. The biota sediment accumulation factors (BSAF) in this study reveals that all the soft tissues of the M. tuberculata snails were macro-concentrators with the exception of Ni; it was deconcentrated, and thus provides that the selective tissues as good biomonitors. The bioconcentration factor (BCF) showed the highest concentrations of Fe and Cu in the soft tissues of the M. tuberculata snail, which has the potential to be used as a biomonitoring agent for Fe and Cu contamination of the water.
Show more [+] Less [-]Hazards of nitrogen fertilizers and ways to reduce nitrate accumulation in crop plants Full text
2020
Ahmed, Moddassir | Reuf, Miḧemed | Akhtar, Muhammad | Mukhtar, Zahid | Saeed, Nasir Ahmad
In modern agriculture, farm produce accumulates a lot of nitrates that can reach toxic levels owing to the unfair use of nitrogen fertilizers, cultural methods, farming policies in multiple areas of the world, thereby increasing concerns about the availability of hygienic food supply and environmental hazards. Over the past few decades, global interest in achieving greater output through intensive fertilization has been a growing trend. The fertilizer based on urea or ammonium mainly yields ammonium, which is then transformed to nitrate through the oxidation process that is biologically mediated. Nitrate tends to accumulate differently in distinct crop plants and distinct components of agricultural commodities based on species, crop variety, genetic history, environmental circumstances, harvest phase, post-harvest storage conditions, agronomic variables, nature, and fertilizer application rate. The current article highlights various factors that could directly or indirectly contribute to the accumulation of nitrates in different parts of crop plants and discusses strategies to minimize the accumulation of nitrates in farm produce, thus ensuring healthy food supply and protecting the environment from the accumulation of nitrates.
Show more [+] Less [-]Asymmetric effects of energy efficiency and renewable energy on carbon emissions of BRICS economies: evidence from nonlinear panel autoregressive distributed lag model Full text
2020
Akram, Rabia | Majeed, Muhammad Tariq | Fareed, Zeeshan | Khalid, Fahad | Ye, Chengang
Embracing energy efficiency (EE) and renewable energy (RE) is essential for improving environmental quality. This research investigates the asymmetric impacts of EE, RE, and other factors on CO₂ emissions in BRICS (i.e., Brazil, Russia, India, China, and South Africa) countries from 1990 to 2014. In contrast to previous studies, the present study considers EE as a major cause of CO₂ emissions in BRICS countries. By using the new hidden panel cointegration and nonlinear panel autoregressive distributive lag model, this study is the first of its kind that unfolds the asymmetric links among EE, RE, and CO₂ emissions. Findings clearly explain that the impact of the selected variables on CO₂ emissions is asymmetric, and both EE and RE help to lower CO₂ emissions in BRICS countries. In the long run, positive shocks in EE and RE can significantly mitigate CO₂ emissions in BRICS economies. In particular, a 1% fluctuation in the positive sum of EE reduces CO₂ emissions by 0.783% in the long run. On the other hand, a 1% fluctuation in the positive component of RE reduces CO₂ emissions by 0.733%. Moreover, individual country estimates suggest the heterogeneous effects among BRICS countries. Based on the empirical findings, policymakers should consider the asymmetric behavior of the EE, RE, and economic growth while formulating, energy, environment, and growth policies of BRICS countries. Graphical abstract
Show more [+] Less [-]Climatic seasonality and water quality in watersheds: a study case in Limoeiro River watershed in the western region of São Paulo State, Brazil Full text
2020
Gomes, Felipe David Georges | Osco, Lucas Prado | Antunes, Patrícia Alexandra | Ramos, Ana Paula Marques
Applying the climatological water balance (WB) concept to describe the relationship between climatic seasonality and surface water quality according to different forms of land use and land cover (LULC) is an important issue, but little explored in the literature. In this paper, we evaluate the influence of WB on surface water quality and its impacts when interacting with LULC. We monitored 11 sampling points during the four seasons of the year, from which we estimate WQI (water quality index) and TSI (trophic state index). We found an effect of the seasonality factor on both WQI values (F(3,30) = 12.472; p < 0.01) and in TSI values (F(3,30) = 6.967; p < 0.01). We noticed that LULC interferes in the way that the water balance influences the WQI and TSI values since in sampling points closest to higher urban density, with little or no riparian protection, the correlation between water balance and water quality was lower. In the stations that had the lowest water surplus and deficit, there was positive linearity between water balance and WQI. However, in the seasons when the surplus and water deficit recorded were extreme, there was no linearity. We conclude that water deficiency impairs the quality of surface water. In the extreme surplus water season, the homogeneity of WQI samples was lower, suggesting a higher interaction between rainwater and LULC. This study contributes to design management strategies of water resources, considering the climatic seasonality for optimization.
Show more [+] Less [-]West Africa’s CO2 emissions: investigating the economic indicators, forecasting, and proposing pathways to reduce carbon emission levels Full text
2020
Ameyaw, Bismark | Li, Yao | Annan, Augustine | Agyeman, Joy Korang
This paper investigates the nexus between carbon emissions (CO₂) and economic growth in West Africa based on the Environment Kuznets Curve (EKC) hypothesis by utilizing spatial panel data technique to check the possible effect of spatial dependence among countries in West Africa. Our empirical findings suggest the presence of spatial dependence of carbon emissions distribution in West Africa. By examining the existence of EKC embedded within the Stochastic Impacts by Regression on Population, Affluence, and Technology (STIRPAT) approach, we conclude an inverse N-trajectory of the relationship between carbon emissions and economic growth. Furthermore, to mitigate global carbon emissions, we utilize a recurrent neural network (RNN) bidirectional long short-term memory (BiLSTM) algorithm devoid of exogenous variables and assumptions to forecast carbon emissions from the year 2015 to the year 2030 based on the predictive accuracy of our formulated algorithm. Due to the upward trends in future emission levels, we propose emissions mitigation pathways for countries in West Africa to still hold carbon emissions-related global warming well below 1.5 and 2 °C. Such mitigation pathways proposed could help implement strategic policies to minimize carbon emissions to a considerable level. As a policy implication, drafting strict environmental regulations and utilizing renewable energy technologies will help mitigate carbon emissions for all West African countries.
Show more [+] Less [-]