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Leaching of metal(loid)s from ashes of spent sorbent and stabilisation effect of calcium-rich additives 全文
2020
Kasiuliene, Alfreda | Carabante, Ivan | Sefidari, Hamid | Öhman, Marcus | Bhattacharya, Prosun | Kumpiene, Jurate
Contaminated water with multiple contaminants, including As, Cr, Cu and Zn, was treated with a sorbent prepared by coating peat with Fe oxides. Because As has a relatively little explored market, the regeneration of the spent sorbent was not feasible. Meanwhile, the disposal of As wastes in landfills can cause landfill leachate treatment problems. Under the reducing conditions prevailing at landfills, As(V) is reduced to As(III), which is a toxic and more mobile form. In this study, incineration was explored as a management option to treat the spent sorbent that was loaded with As, Cr, Cu and Zn. The first objective of this study was to evaluate the leaching of these metal(loid)s from the ashes and compare it with the leaching from the spent sorbents before incineration. The second objective was to evaluate the leaching behaviour when the spent sorbent was co-incinerated with a Ca-rich additive (lime). To achieve these objectives, the obtained ashes were subjected to leaching tests, sequential extraction, and X-ray diffraction analyses. After the incineration, the ash content ranged from 9 to 19% of the initial mass of the spent sorbents. The leaching of As, Cu and Zn decreased compared with that from the spent sorbents before the thermal treatment because of the high incineration temperatures and/or co-incineration with lime. However, the leaching of Cr increased, which would hinder the disposal of the obtained ashes in a landfill because the limit value for disposal at a landfill for hazardous wastes was exceeded by 50 times. However, co-incineration with 10 wt% lime significantly decreased the leaching of Cr as a result of the formation of water-insoluble Ca-Cr compounds.
显示更多 [+] 显示较少 [-]Macroelement, trace element, and toxic metal levels in leaves and infusions of yerba mate (Ilex paraguariensis) 全文
2020
Olivari, Ilaria | Paz, Soraya | Gutiérrez, Ángel J. | González-Weller, Dailos | Hardisson, Arturo | Sagratini, Gianni | Rubio, Carmen
Mate is an infusion made from the dried leaves of yerba mate (Ilex paraguariensis). Yerba mate may be an important source of essential elements but could contain toxicologically relevant metals. Macroelements (Ca, Mg, Na, K), trace elements (B, Ba, Sr, V, Li, Ni, Fe, Zn, Cu, Cr, Co, Mn, Mo), and toxic metals (Al, Cd, Pb) content have been determined in 32 samples of yerba mate by ICP-OES (inductively coupled plasma—optical emission spectrometry) with the aim of determining the element content of yerba mate leaves and the influence of temperature in the extraction of these elements from the plant to the infusion, and estimating the dietary intake for each element studied. The highest element contents have been found in infusions prepared with hot distilled water (70–75 °C); the most noteworthy are K (303 mg/L), Mn (4.85 mg/L), and Al (4.52 mg/L). The consumption recommended by the producers (500 mL infusion/day) contributes significantly to the daily intake of essential elements such as Mn, Mg, and Cu. This consumption does not pose a health risk, although it is necessary to assess the risk/benefit of Ni intake from mate consumption for people with impaired renal function (500 mL/day accounts for 52.2% of the TDI).
显示更多 [+] 显示较少 [-]Distribution and potential risk assessment of antibiotic pollution in the main drinking water sources of Nanjing, China 全文
2020
Liu, Yanhua | Feng, Mengjuan | Wang, Bo | Zhao, Xin | Guo, Ruixin | Bu, Yuanqing | Zhang, Shenghu | Chen, Jianqiu
The distribution character of 41 antibiotics belonging to 6 groups, sulfonamides (SAs), quinolones (QUs), tetracyclines (TCs), macrolides (MLs), penicillins (PLs), and chloramphenicol (CHL), was investigated in drinking water sources of Nanjing during 2017–2019. MLs (42.98%) were the most abundant category, followed by SAs (25.94%) and QUs (22.52%). The dominant antibiotic was ofloxacin (OFX) in Dec. 2017 (average concentration, 3.14 ng/L; range, ND–35.20 ng/L) and Nov. 2018 (2.16 ng/L, ND–12.26 ng/L), and sulfadiazine (SDZ) in Mar. 2019 (16.37 ng/L, ND–25.90 ng/L). For Dec. 2017, the total concentrations in Zhongshan Waterworks (S15) and Jinniushan Reservoir (S16) were significantly higher than the other sampling sites, which may be attributed to point source pollution. The ecological and human risk of the main antibiotics was assessed by risk quotients (RQs) and target hazard quotient (THQ), respectively. Most of the RQ values were below 0.1, except enrofloxacin (ERX, 0.11) and enoxacin (ENX, 0.62) in Dec. 2017, lomefloxacin (LOM, 0.14) in Nov. 2018, and LOM (0.28) and ERX (0.10) in Mar. 2019. This indicated that the risk of the target antibiotics to aquatic organisms in the 3 years was moderate or low level. Meanwhile, results of the THQ values showed that antibiotic exposure caused no risk to human health. This research provides scientific information for antibiotic pollution control and enriches environmental monitoring data in the drinking water sources.
显示更多 [+] 显示较少 [-]Traffic noise prediction model of an Indian road: an increased scenario of vehicles and honking 全文
2020
Thakre, Chaitanya | Laxmi, Vijaya | Vijay, Ritesh | Killedar, Deepak J. | Kumar, Rakesh
Noise is considered as an underrated and underemphasized pollutant in contrast to other pollutants of the environment. Due to the non-acute response of health effects, people are not vigilant towards consequences regarding noise pollution. The expansion of the transportation industry is contributing towards the increment in the public and private vehicular volume which causes an increment in noise pollution. For evaluation of respective scenario, the research study has been conducted on one of the minor roads of Nagpur, India; for 2 years, viz., 2012 and 2019. The study concludes an increment of 5–6 dB(A) in noise level, 4–6 times in honking, and 1.7 times in traffic volume. The study confirms increment in sound pressure by 65.9% and 81.9% for the year 2012 and 2019 during morning and evening sessions, respectively. Noise prediction model has also been developed for the abovementioned years, using multiple regression analysis, considering traffic volume, honking, and speed against noise equivalent level. Honking has been further characterized into honk by light and medium category vehicles as acoustical properties of horns vary with respect to category of vehicle and introduced into the noise prediction model. Noise prediction model for 2019 has predicted the noise level in a range of − 1.7 to + 1.4 dB (Leq) with 84% of observations in the range of − 1 to + 1 dB (Leq), when compared with observed Leq on the field. For proper management of noise pollution, a noise prediction model is essentially needed so that the noise level can be anticipated, and accordingly, measures can be outlined and executed. This increased noise level has serious impacts on human hearing capacity and overall health. Accordingly, noise mitigation preventive measures are recommended to control traffic noise in the urban environment.
显示更多 [+] 显示较少 [-]Integrated geophysical and geochemical methods applied for recognition of acid waste drainage (AWD) from Zn-Pb post-flotation tailing pile (Olkusz, southern Poland) 全文
2020
Pierwoła, Jolanta | Szuszkiewicz, Marcin | Cabała, Jerzy | Jochymczyk, Krzysztof | Żogała, Bogdan | Magiera, Tadeusz
Long-term underground exploitation of Zn-Pb ores has led to drainage of the area and formation of a huge dumping ground in the form of a pile. In its vicinity, processes of acid drainage have developed as a result of contamination of soils and groundwater. Geochemical transformations of mineral contents of waste can significantly affect physical and chemical properties of the soils and the bedrock. At the prospect of termination of the mining activity in the near future, determining the routes of the pollution migration, ability to monitor acid drainage processes and assessment of the risk of heavy metal pollution are really crucial. The paper presents a proposal for solving this problem by means of geophysical methods: Electrical Resistivity Tomography (ERT), Time Domain-Induced Polarisation (TDIP), Frequency Domain Electromagnetics (FDEM) and shallow-depth magnetometric surveys combined with geochemical investigations. The obtained results of geophysical surveys have been confirmed by geochemical investigations. The applied ERT and TDIP methods make it possible to identify the spread of the zones of pollution around the tailing pile, but their effectiveness depends on humidity of the ground. Soil magnetometry and shallow-depth induction profiling are a good tool to identify the medium contaminated with minerals redeposited by aeolian processes and allow to determine the range of the dust spread from the pile. It has been shown that the range of impact of the geochemical changes around the tailing pile is high and depends not only on directions and dynamics of water flow from the pile but also on aeolian transport.
显示更多 [+] 显示较少 [-]Monitoring of a mound made of sediments: exploring landscaping as a way to upgrade dredged materials (VALSE project) 全文
2020
Liénard, Florian | Haouche, Laurence
Because of the shallow relief in Belgium and northern France, the dredging of waterways generates significant quantities of sediments for which few valorization pathways are validated. Waterways operators and public authorities are still waiting for efficient valorization solutions. The VALSE project, funded by the Interreg V FWVl program, aims to validate valorization pathways through large-scale works that promote a good integration in territories and a sustainable use. In this context, landscaping could be an upgrading solution; hence, a mound made with unpolluted sediments is ecologically and ecotoxicologically monitored over time to assess if dredged materials are harmful for the environment. An embankment near the studied site was chosen as a reference. The monitoring consists of, on the one hand, in situ flora and substrate macro-invertebrates surveys. On the other hand, ecotoxicity tests are performed on sediments and soil respectively taken from the mound and the embankment: the activity of nitrifying bacteria in these substrates and the reproduction of an earthworm (Eisenia fetida) are studied. First, results show that the sediments do not seem to impact negatively plant colonization or the settlement of substrate macro-invertebrates. About laboratory testing, sediments do not seem to interfere with natural nitrification process and E. fetida reproduction seems equivalent in sediments and embankment soil. These results do not allow drawing any definite conclusion because they relate to a first year of experimentation only, but they tend towards a good integration of the mound in the surrounding environment for the monitored parameters.
显示更多 [+] 显示较少 [-]Biodegradable chitosan-ethylene glycol hydrogel effectively adsorbs nitrate in water 全文
2020
Chen, Changhong | Guo, Yiwei | Long, Li | Chen, Keyan | Hudielan, | Xue, Yingwen
Nitrate, existing as inorganic anions in water, possesses high water-solubility and has caused lots of contaminations around the world. It is thus extremely urgent to develop an effective method to effectively remove nitrate from water in a sustainable way. In this study, chitosan-ethylene glycol hydrogel (CEGH) was synthesized using the repeated freezing-thawing procedure. A range of batch sorption experiments were conducted to evaluate CEGH as a nitrate sorbent. The adsorption isotherms of nitrate onto CEGH followed the Langmuir model with coefficient of determination of 0.98 and a maximum Langmuir adsorption capacity of 49.04 mg/g, which is higher than that of other adsorbents. The adsorption of nitrate onto CEGH was affected by pH value and temperature. The results indicate that the main removal mechanism was polarity of CEGH molecules given by functional group O–H and N–H and hydrogen bond interaction between CEGH and nitrate molecules under acidic conditions. Therefore, CEGH, a biodegradable carbon-rich adsorbent, can be widely applied to remove nitrate in wastewater treatment and water body remediation.
显示更多 [+] 显示较少 [-]Study on the correlation between mechanical and oxidation characteristics of methanol/biodiesel particulate matter 全文
2020
Lichuanjushi, | Zhang, Libin | Wang, Zhong | Li, You | Sun, Yong
In order to effectively reduce the number of diesel exhaust particles and reduce particulate emissions, it is necessary to have a deep understanding of the mechanical and oxidation characteristics of diesel exhaust particles. For the combustion particles of methanol/biodiesel (BM5, BM10, and BM15), atomic force microscopy and thermogravimetric analyzers were used to study changes of particle in mechanical parameters and oxidation rules, and association impact analysis was performed. Biodiesel (B100) was used as a reference. The results showed that with the increase of methanol content, the attraction force Fₐₜ, the cohesive force Fₐd, the adhesion energy Wₐd, and Young’s modulus E of the methanol/biodiesel particles all decreased significantly. During the oxidation process, the weight loss rate of SOF increased, while the content of soot decreased. In addition, the initial combustion temperature of the SOF component TSOF and soot component Tₛₒₒₜ in particles as well as the burn-out temperature Tₑₙd showed a downward trend. There was a certain correlation between the mechanical parameters and the oxidation properties of the particles. The smaller the mechanical parameters, such as the attraction force Fₐₜ, viscous force Fₐd, the cohesive force Fₐd, the adhesion energy Wₐd, and Young’s modulus E, the greater the looseness of the particles, the smaller the particle hardness and the degree of graphitization.
显示更多 [+] 显示较少 [-]MOA-based linear and nonlinear QSAR models for predicting the toxicity of organic chemicals to Vibrio fischeri 全文
2020
Zhang, Shengnan | Wang, Ning | Su, Limin | Xu, Xiaoyan | Li, Chao | Qin, Weichao | Zhao, Yuanhui
Risk assessment of pollutants to humans and ecosystems requires much toxicological data. However, experimental testing of compounds expends a large number of animals and is criticized for ethical reasons. The in silico method is playing an important role in filling the data gap. In this paper, the acute toxicity data of 1221 chemicals to Vibrio fischeri were collected. The global models obtained showed that there was a poor relationship between the toxicity data and the descriptors calculated based on linear and nonlinear regression analysis. This is due to the fact that the studied compounds contain not only non-reactive compounds but also reactive and specifically acting compounds with different modes of action (MOAs). MOAs are fundamental for the development of mechanistically based QSAR models and toxicity prediction. To investigate MOAs and develop MOA-based prediction models, the compounds were classified into baseline, less inert, reactive, and specifically acting compounds based on the modified Verhaar’s classification scheme. Satisfactory models were established by multivariate linear regression (MLR) and support vector machine (SVM) analysis not only for baseline and less inert chemicals, but also for reactive and specifically acting compounds. Compared with linear models obtained by the MLR method, the nonlinear models obtained by the SVM method had better performance. The cross validation proved that all of the models were robust except for those for reactive chemicals with nN (number of nitrogen atoms) = 0 and n(C=O) (number of carbonyl groups) > 0 (Q²ₑₓₜ < 0.5). The application domains and outliers are discussed for those MOA-based models. The models developed in this paper are significantly helpful not only because the application domains for baseline and less inert compounds have been expended, but also the toxicity of reactive and specifically acting compounds can be successfully predicted. This work will promote understanding of toxic mechanisms and toxicity prediction for the chemicals with structural diversity, especially for reactive and specifically acting compounds.
显示更多 [+] 显示较少 [-]The financial development-environmental degradation nexus in the United Arab Emirates: the importance of growth, globalization and structural breaks 全文
2020
Shahbaz, Muhammad | Haouas, Ilham | Sohag, Kazi | Ozturk, Ilhan
This article revisits the nexus between financial development and environmental degradation by incorporating economic growth, electricity consumption and economic globalization in the CO₂ emissions function for the period 1975QI–2014QIV in the United Arab Emirates. We apply structural break and cointegration tests to examine unit root and cointegration between the variables. Further, the article also uses the Toda-Yamamoto causality test to investigate the causal relationship between the variables and tests the linkages of the robustness of causality by following the innovative accounting approach. Our empirical analysis shows cointegration between the series. Financial development increases CO₂ emissions. Economic growth is positively linked with environmental degradation. Electricity consumption improves environmental quality. Economic globalization affects CO₂ emissions negatively. The relationship between financial development and CO₂ emissions is U-shaped and inverted N-shaped. Further, financial development leads to environmental degradation, and environmental degradation in turn leads to financial development in the Granger sense.
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