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Metal toxicity and natural antidotes: prevention is better than cure Full text
2020
Rajak, Chetan | Singh, Neelu | Parashar, Poonam
Toxicity due to heavy metals (HM), specifically mercury (Hg), arsenic (As), lead (Pb), and cadmium (Cd) remains a challenge to scientists till date. This review gives insights into natural antidotes for the management and prevention of HM toxicity. Various databases such as PubMed, Embase, and Science Direct were searched for available facts on natural antidotes and their commercial products against HM toxicity till date. Toxicity owing to such metals needs prevention rather than therapy. Natural antidotes, fruits and vegetables, rich in antioxidant are the answers to such toxicities. Synthetic chelators impart a major drawback of removing essential metals required for normal body function, along with the toxic one. Natural antioxidants are bestowed with scavenging and chelation properties and can be alternative for synthetic chelating agents. Natural compounds are abundantly available, economic, and have minimal side effects when compared with classical chelators. Prevention is better than cure and thus adding plentiful vegetables and fruits to our diet can combat HM toxicity-related illness. Graphical abstract
Show more [+] Less [-]Isotherm, kinetic, and thermodynamic studies for dynamic adsorption of toluene in gas phase onto porous Fe-MIL-101/OAC composite Full text
2020
Khoshakhlagh, Amir Hossein | Beygzadeh, Mojtaba | Golbabaei, Farideh | Saadati, Zohreh | Carrasco-Marín, Francisco | Shahtaheri, Seyed Jamaleddin
In the present paper, micro-mesoporous Fe-MIL-101/OAC composite using in situ incorporation of Fe-MIL-101 into oxidized activated carbon was synthesized and characterized by XRD, FT-IR, SEM, EDS, and BET techniques. The adsorption performances of toluene onto adsorbents in the gas phase were studied using a laboratory-scale dynamic adsorption system under moist ambience. The toluene adsorption capacity of Fe-MIL-101/OAC composite and Fe-MIL-101 were 127 and 97.6 mg g⁻¹, severally. Results revealed that the larger pores in micro-mesoporous Fe-MIL-101/OAC enhanced the molecular diffusion rate. The findings indicated that micro-mesoporous structures played key roles in the capture of toluene molecules. The initial toluene concentration positively affected on toluene adsorption capacity while temperature and humidity negatively affected on toluene adsorption capacity. The Langmuir model and the pseudo-second-order kinetics model described better adsorption process of Fe-MIL-101/OAC composite. Thermodynamic findings determined that toluene adsorption over Fe-MIL-101/OAC was spontaneous, exothermic physisorption. The regeneration of the composite was still up to 72.6% after six cycles. The micro-mesoporous Fe-MIL-101/OAC composite proposes a promising support for the high toluene removal for future. Graphical abstract
Show more [+] Less [-]Nexus among CO2 emissions, remittances, and financial development: a NARDL approach for India Full text
2020
Neog, Yadawananda | Yadava, Anup Kumar
The nexus of remittances and CO2 emission is very important and gathers a significant place in empirical research. This paper tries to find out the asymmetric relationship between carbon emissions, remittances, and financial development in India for the period 1980–2014. Based on the theoretical linkages, we develop a nonlinear ARDL model with the use of time series data in this study. The results of the NARDL bound test suggest that there is long-run cointegration among the variables. The findings show that positive shock in remittances causes an increase in CO2 emissions, where negative shock reduces it. The coefficient for financial development is positive but becomes statistically insignificant. Empirical results also support the existence of asymmetric long-run relationship among the variables. Based on the findings, the paper recommends the proper channelization of remittances and financial development towards environment-friendly energy sources and projects without compromising economic growth.
Show more [+] Less [-]Possible Factors Influencing the Accumulation of Different Radionuclides in Sludge from a Drinking Water Treatment Plant Located in Southern Catalonia Between 2002 and 2018 Full text
2020
Peñalver, A. | Baciu, T. | Borrull, F. | Aguilar, C.
The drinking water treatment plant (DWTP) in L’Ampolla collects water from the River Ebro. The sludge generated during the water treatment processes applied accumulates some of the radionuclides present in the ingoing water. Gamma spectrometry measurements of the sludge were carried out monthly for a period of 17 years (2002–2018) to evaluate possible factors that might influence the radioactive content. These included the geology, river flow rate, suspended particulate matter, turbidity, water treatment processes, and industrial activities in the area of the river basin. The activity concentrations of ²¹⁴Pb, ²¹⁴Bi, ²²⁸Ac, ²²⁸Ra, and ²²⁶Ra from both the ²³⁸U and ²³²Th decay chains decreased significantly from 2012 onwards. This may be related to a change in the water treatment process in the L’Ampolla DWTP, and in particular, that potassium permanganate was no longer added to the raw water from 2011. Other isotopes such as ⁴⁰K, ⁷Be, and ²³⁴U/²³⁸U have not displayed the same behavior, which could support our hypothesis that the accumulation of radium isotopes in the sludge could be influenced by the use and nonuse of permanganate. A number of artificial radionuclides were also determined, which is consistent since L’Ampolla DWTP is located 70 km from a nuclear power plant, and the activities found for some of these radionuclides correlate with its annual liquid discharges into the river. The results therefore indicate that a relationship exists between the different factors in connection with the raw water and the radioactive content of the sludge generated by the plant under study.
Show more [+] Less [-]Desulfurization Performances of Activated Coke Prepared from Fine Blue-Coke Full text
2020
Tian, Yuhong | Hu, Shudi | Jing, Xian de | Xue, Juanqin | Song, Yonghui | Lan, Xinzhe
Activated coke was prepared by CO₂ activation using solid waste fine blue-coke as main raw material and coal direct liquefaction residue (DCLR) as binder. The activated coke was characterized by BET, XRD, and infrared analysis. The flue gas desulfurization experiment was carried out with a fixed bed reactor and activated coke as the adsorbent. The experimental results show that coal direct liquefaction residue pyrolysis process will produce a large number of cohesive colloids, further increasing the strength of the activated coke. BET analysis shows that there is abundant microporous structure in the activated coke, infrared analysis shows that the activated coke contains abundant surface functional groups, and XRD shows that the crystallization degree of the activated coke is high. At lower temperature, SO₂ and O₂ have competitive adsorption on the surface of activated coke, if the concentration of water vapor is too high, a water film will be formed on the surface of activated coke, which will hinder the adsorption of SO₂ by activated coke. The initial concentration of SO₂ is 700 ppm, the adsorption temperature is 80 °C, the oxygen concentration is 9%, and the concentration of water vapor is 8%. The removal of SO₂ by activated coke is better, and the desulfurization rate reaches 97%.
Show more [+] Less [-]Biogeochemical transformation of greenhouse gas emissions from terrestrial to atmospheric environment and potential feedback to climate forcing Full text
2020
Shakoor, Awais | Ashraf, Fatima | Shakoor, Saba | Muṣṭafá, ʻAdnān | Rehman, Abdul | Altaf, Muhammad Mohsin
Carbon dioxide (CO₂) is mainly universal greenhouse gas associated with climate change. However, beyond CO₂, some other greenhouse gases (GHGs) like methane (CH₄) and nitrous oxide (N₂O), being two notable gases, contribute to global warming. Since 1900, the concentrations of CO₂ and non-CO₂ GHG emissions have been elevating, and due to the effects of the previous industrial revolution which is responsible for climate forcing. Globally, emissions of CO₂, CH₄, and N₂O from agricultural sectors are increasing as around 1% annually. Moreover, deforestation also contributes 12–17% of total global GHGs. Perhaps, the average temperature is likely to increase globally, at least 2 °C by 2100—by mid-century. These circumstances are responsible for climate forcing, which is the source of various human health diseases and environmental risks. From agricultural soils, rhizospheric microbial communities have a significant role in the emissions of greenhouse gases. Every year, microbial communities release approximately 1.5–3 billion tons of carbon into the atmospheric environment. Microbial nitrification, denitrification, and respiration are the essential processes that affect the nitrogen cycle in the terrestrial environment. In the twenty-first century, climate change is the major threat faced by human beings. Climate change adversely influences human health to cause numerous diseases due to their direct association with climate change. This review highlights the different anthropogenic GHG emission sources, the response of microbial communities to climate change, climate forcing potential, and mitigation strategies through different agricultural management approaches and microbial communities.
Show more [+] Less [-]Herbicides based on 2,4-D: its behavior in agricultural environments and microbial biodegradation aspects. A review Full text
2020
Magnoli, Karen | Carranza, Cecilia Soledad | Aluffi, Melisa Eglé | Magnoli, Carina Elizabeth | Barberis, Carla Lorena
One of the main herbicides used in the agricultural environments is 2,4-dichlorophenoxyacetic acid (2,4-D). It is a synthetic plant hormone auxin employed in many crops including rice, wheat, sorghum, sugar cane, and corn to control wide leaf weeds. The indiscriminate use of pesticides can produce numerous damages to the environment. Therefore, this review has the objective to provide an overview on the main characteristics of the herbicides based on 2,4-D, mostly on the role of microorganisms in its degradation and its main degradation metabolite, 2,4- dichlorophenol (2,4-DCP). The remediation processes carried out by microorganisms are advantageous to avoid the pollution of the environment as well as to safeguard the population health.
Show more [+] Less [-]Winter Rye Cover Crop Impacts on Runoff Water Quality in a Northern New York (USA) Tile-Drained Maize Agroecosystem Full text
2020
Griffith, Keegan E. | Young, Eric O. | Klaiber, Laura B. | Kramer, Stephen R.
Nonpoint source phosphorus (P) and nitrogen (N) pollution from agriculture is a global concern. Planting a cover crop after harvesting annual crops such as maize may help mitigate nutrient transport risk to surface and groundwater. Few studies have focused on the impact of a winter rye cover crop on both surface runoff (SR) and tile drainage (TD) water quality. Here, we measured N and P losses in SR and TD from maize plots grown with and without a winter rye cover crop. Four plots (46 × 23 m) in northern New York, USA, equipped with automated SR and TD flow monitoring were planted with winter rye (Secale cereal) in 2016 and 2017 after maize silage harvest. Plots were managed as typical silage fields for dairy farms in the region and received fertilizer and manure applications. Dissolved reactive P (DRP), total P (TP), nitrate-N, total N (TN), and total suspended solids (TSS) loads were monitored from 4/7/16 to 6/29/17. Cumulative SR (volumetric depth equivalent) was 1.8-fold lower for rye compared to control plots. Although runoff and loading were variable, cumulative TSS, TP, and DRP losses were approximately 3-fold lower for rye plots compared to control. Cumulative TN and nitrate-N loads for TD were similar; however, cumulative TN loss for SR was lower for rye plots. Surface runoff was the main pathway of P loss (> 90% of DRP and TP loss) with > 90% of cumulative P exported from 2017 snowmelt events. Results suggest winter rye mitigated N and P transport risk in SR compared to the common practice of leaving maize silage fields bare after harvest.
Show more [+] Less [-]The effects of FDI, technological innovation, and financial development on CO2 emissions: evidence from the BRICS countries Full text
2020
Rafique, Muhammad Zahid | Li, Yafei | Larik, Abdul Razaque | Monaheng, Malepekola Precious
The scholars of environmental economics have attempted the investigation of the impact of foreign direct investment-growth nexus, but they have missed the essential role played by technological innovation and financial development regarding the environmental costs. The notable economic growth and the consequent speedy process of urbanization in BRICS countries have brought about colossal escalation of energy needs leading to environmental degradation. The present study endeavors to explore the effect of foreign direct investment, technological innovation, and financial development on carbon emissions in BRICS member countries, with data from 1990 to 2017. The results verify a strong cross-sectional dependence within the panel countries. The Augmented Mean Group (AMG) estimator shows that foreign direct investment, technological innovation, and financial development in the BRICS countries possess a negative and statistically significant long-run association with CO₂ emissions, while economic growth, trade openness, urbanization, and energy use are found to contribute statistically significant and positive with carbon emissions. The current study chose to employ the Dumitrescu and Hurlin panel causality test for examining the direction of causality. Findings reveal a bidirectional long-run causality running among financial development, economic growth, trade openness, urbanization, energy use, and CO₂ emissions; on the contrary, unidirectional causality is found between foreign direct investment and carbon emissions. Consequently, for the BRICS member countries, the development of industries, financial institutions, and development of technological innovation are required to attract quality foreign direct investment. Moreover, urbanization contributes enormously to environmental degradation and necessitates urgent policy responses in these countries.
Show more [+] Less [-]The presence of heavy metals in Avicennia schaueriana Stapf & Leechman ex Moldenke leaf and epicuticular wax from different mangroves around Sepetiba Bay, Rio de Janeiro, Brazil Full text
2020
Victório, Cristiane Pimentel | dos Santos, Mayara Silva | de Mello, Marise Costa | Bento, João Pedro Silvério Pena | da Costa Souza, Marcelo | Simas, Naomi Kato | do Carmo de Oliveira Arruda, Rosani
This study aimed to investigate the leaf epicuticular wax and the presence of heavy metals in leaves of Avicennia shaueriana, a halophyte found in Brazilian mangroves. We evaluated plants collected in mangroves located around Sepetiba Bay, Rio de Janeiro State. Heavy metals were analyzed by energy dispersive X-ray spectroscopy (EDS or EDX) and inductively coupled plasma optical emission spectrometry (ICP-OES). Chemical analysis of epicuticular wax was made by gas chromatography–mass spectrometry (GC-MS). We also evaluated the micromorphology of leaf surface using scanning electronic and light microscopy. The leaves from each mangrove presented alterations in wax layer. Fagarasterol (lupeol) in high quantity was the main triterpene identified in the leaf wax from plants collected in all mangroves: Coroa Grande (76.43%), Pedra de Guaratiba (38.91%), and Marambaia (62.56%). Al, Fe, Mn, and Zn were the main heavy metals detected in leaves from the three mangroves by ICP-OES. Thus, we show that that plants able to survive in the mangrove swamp can adapt to the exposure of heavy metals, accumulate them in their leaves, and be used in coastal area recovery projects as a phytoremediator.
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