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Degradation of doxycycline antibiotics using lanthanum copper oxide microspheres under simulated sunlight Full text
2022
Prabagar, Jijoe Samuel | Yashas, Shivamurthy Ravindra | Gurupadayya, Bannimath | Wantala, Kitirote | Diganta, Das Bhusan | Shivaraju, Harikaranahalli Puttaiah
In this study, lanthanum copper oxide was synthesized under hydrothermal techniques and characterized for doxycycline degradation. The catalyst exhibited enhanced photocatalytic doxycycline degradation under visible light owing to its compatible bandgap energy (1.7 eV). The XRD data revealed high crystallinity of the material with no noticeable impurities. Three-dimensional microspheres of varying sizes (average diameter of 2.52 μm) were observed from SEM. EDX confirms the successful synthesis of La₂CuO₄. The effect of DC concentration, catalyst dosage, and initial pH on the degradation rate of DC was studied methodically. Interestingly, about 85% of doxycycline (10 mg/L) was degraded within 120 min of light-emitting diode irradiation at pH 10. Oxygen vacancies and surface defects were determined through photoluminescence spectra. The recyclability experiments suggested that the catalyst is capable of degrading DC for three consecutive runs. Radical trapping trials suggested that holes (h⁺), superoxide radicals (●O₂⁻), and hydroxyl radicals (●OH) are involved in the photodegradation of DC. Herein, the novel approach of La₂CuO₄ synthesis and the efficient visible-light harvesting capability of as-prepared catalyst reveal the potentiality for DC degradation thereby opening a new horizon of research employing La₂CuO₄ used for various environmental applications.
Show more [+] Less [-]Preparation of BiFeO3 and photodegradation of tetracycline pollutant in the UV-heterogeneous Fenton-like system Full text
2022
Jiang, Yongwei | Xing, Chao | Chen, Yue | Shi, Jing | Wang, Sheng
Surplus tetracycline in the water body causes damage to the ecology balance and human health. Therefore, this work established an efficient strategy, namely, the BFO-based UV-heterogeneous Fenton-like system, to eliminate TC pollution. The photocatalytic oxidation system has been integrated with the heterogeneous Fenton-like system, cooperated with the photolysis of H₂O₂. These synergistic effects could boost the generation of reactive species for the TC degradation and mineralization, due to the reduction of Fe(III) to Fe(II) by photogenerated electrons and the separation of photogenerated electron–hole pairs. The prepared BFO was stable with no secondary pollution, and could be recovered by an extra magnet to reuse. Compared with other single oxidation systems, this coupled system showed an outstanding performance in TC disposal, and TC and TOC removal efficiencies could reach 100% and 74.92%, respectively. Moreover, the mechanisms for TC degradation involved that TC was degraded by oxidation species, such as superoxide radicals, hydroxyl radicals, and positive holes, and intermediate products in the TC degradation process mainly were products at m/z = 459, m/z = 445, and m/z = 134. The promising TC disposal efficiency achieved by the integration between BFO-based photocatalytic and heterogeneous Fenton-like system sheds light on applying BFO to control water pollution.
Show more [+] Less [-]Arbuscular Mycorrhiza Reduced Nitrogen Loss via Runoff, Leaching, and Emission of N2O and NH3 from Microcosms of Paddy Fields Full text
2022
Zhang, Shujuan | Yun, Wenfei | Xia, Yu | Wu, Sikai | You, Zhaoyang | Matthias C. Rillig,
This study aims to investigate the role of arbuscular mycorrhizal (AM) symbiosis in reducing N loss from paddy fields, using two rice lines: a mycorrhiza-defective rice line (non-mycorrhizal) and its mycorrhizal progenitor. Two rice lines were grown in the presence of an AM fungal isolate. In this study, N loss of runoff, leaching, N₂O emission, and NH₃ volatilization were measured, and in addition, N uptake of rice, soil aggregates, and plant available N concentration of soil. The results obtained suggest that N loss via runoff, leaching, NH₃ volatilization, and N₂O emission of mycorrhizal rice was 11%, 8%, 6%, and 1%, lower than that of non-mycorrhizal rice, respectively. Meanwhile, mycorrhizal rice has higher biomass and plant N uptake. Our study shows that the AM symbiosis contributes to the sustainability of rice production by reducing N loss, enhancing soil aggregation and increasing plant N uptake.
Show more [+] Less [-]The club convergence of green productivity across African countries Full text
2022
Shen, Zhiyang | Shao, Anqi | Chen, Jiayi | Cai, Jinyang
This study investigates economic convergence and sustainable development in Africa. By introducing an aggregate production technology and directional distance function, it examines the productivity growth of 28 African economies from 1990 to 2019. The proposed approach considers all decision-making units (countries) as a whole, and the productivity gains are then estimated under a nonparametric framework. In the empirical analysis, the carbon emissions are included in the Luenberger productivity measurement, called green productivity. The results show that the annual average growth rate of green productivity is 1.51% in African, and different types of club convergence for green productivity indicator and its decomposition are observed during the sample period. The decomposition of the Luenberger indicator shows that green African growth is mainly driven by technological progress, not efficiency change. Furthermore, the overall inefficiency is decomposed into technical and structural effects. The latter measure the potential improvement in terms of resource reallocation. Structural inefficiency is larger than technical inefficiency, suggesting that African countries could improve their economic and environmental performances by optimizing input/output mixes.
Show more [+] Less [-]Contract farming, social trust, and cleaner production behavior: field evidence from broiler farmers in China Full text
2022
Mao, Hui | Fu, Yong | Cao, Guangqiao | Chen, Shaojian
Pollution from livestock and poultry is the main source of rural pollution, which directly affects the rural ecological environment as well as the quality and safety of agricultural products. Based on field experiment data on broiler farmers in China, this paper analyzes farmers’ cleaner production behavior from the perspective of incomplete contracts and social trust. We find that social trust can promote farmers’ cleaner production behavior. Moreover, our evidence suggests that contract farming (CF) has a significant positive effect on farmers’ social trust and cleaner production behaviors. Further analysis indicates that CF not only directly promotes farmers’ cleaner production, but can also indirectly promote farmers’ cleaner production by improving their interpersonal trust and institutional trust. Overall, this paper offers a new point of view for improving the rural environment and sheds light upon how the government can formulate relevant policies to promote farmers’ cleaner production behavior.
Show more [+] Less [-]Wind energy and CO2 emissions: AMG estimations for selected countries Full text
2022
Güney, Taner | Üstündağ, Emrah
This study analyzes the relationship between wind energy consumption, coal energy consumption, globalization, economic growth, and carbon emissions. Data from 37 countries for the period 2000–2019 are included in the analysis. To examine the long-term relationship between the variables, the AMG method, which considers the cross-section dependence and slope homogeneity, was used. According to the long-term coefficient estimates of the cointegrated variables, wind energy consumption has a statistically significant and negative effect on carbon emissions in the long run. For example, a 1% increase in wind energy consumption reduces carbon emissions by 0.018%. On the other hand, the variable of globalization has a statistically significant and positive effect on carbon emissions in the long run. A 1% increase in globalization increases carbon emissions by 0.107%. These findings show the importance of wind energy consumption in reducing carbon emissions.
Show more [+] Less [-]Seasonal and inter-annual variability of bacterioplankton communities in the subtropical Pearl River Estuary, China Full text
2022
Mai, Yongzhan | Peng, Songyao | Lai, Zini | Wang, Xuesong
It is widely recognized that environmental factors substantially influence on the seasonal and inter-annual variability of bacterioplankton communities, yet little is known about the seasonality of bacterioplankton communities in subtropical estuaries at longer-term time scales. Here, the bacterioplankton communities from the eight major outlets of the subtropical Pearl River Estuary were investigated across 3 years (2017–2019) using full-length 16S rRNA gene sequencing. Significant seasonal and inter-annual variation was observed in bacterioplankton community compositions across the 3 years (p < 0.05). In addition, the inferred functional composition of the communities varied with seasons, although not significantly, suggesting that functional redundancy existed among communities and across seasons that could help to cope with environmental changes. Five evaluated environmental parameters (temperature, salinity, pH, total dissolved solids (TDS), total phosphorus (TP)) were significantly correlated with community composition variation, while only three environmental parameters (temperature, pH, and TDS) were correlated with variation in inferred functional composition. Moreover, community composition tracked the seasonal temperature gradients, indicating that temperature was a key environmental factor that affected bacterioplankton community’s variation along with seasonal succession patterns. Gammaproteobacteria and Alphaproteobacteria were the most dominant classes in the surface waters of Pearl River Estuary, and their members exhibited divergent responses to temperature changes, while several taxa within these group could be indicators of low and high temperatures that are associated with seasonal changes. These results strengthen our understanding of bacterioplankton community variation in association with temperature-dependent seasonal changes in subtropical estuarine ecosystems.
Show more [+] Less [-]The roles of foreign direct investments, economic growth, and capital investments in decarbonizing the economy of Oman Full text
2022
Hamid, Ishfaq | Alam, Md. Shabbir | Murshed, Muntasir | Jena, Pabitra Kumar | Sha, Nadia | Alam, Mohammad Noor
Oman is a Middle Eastern country that has traditionally been monotonically reliant on its indigenous fossil fuel supplies. Besides, the nation has also been a surplus producer and net exporter of oil which further highlights the prolonged fossil fuel dependency of Oman. Consequently, despite flourishing economically, environmental quality in Oman has persistently aggravated. These opposing economic and environmental performances have necessitated Oman to identify the factors which can enable Oman to decarbonize its economy for tackling the environmental concerns faced by the nation. Against this backdrop, this study aims to examine the symmetric and asymmetric effects of foreign direct investments, economic growth, and capital investments on carbon dioxide emissions in Oman during 1980–2019. Using relevant econometric estimation methods for controlling structural break concerns in the data, the findings reveal evidence of asymmetric environmental impacts associated with shocks to the nation’s foreign direct investment inflow, economic growth, and capital investment figures. Specifically, it is witnessed that positive shocks to the levels of foreign direct investment inflows, economic growth, and capital investments boost carbon dioxide emissions both in the short and long run. On the other hand, negative shocks to the levels of foreign direct investment inflows and economic growth are witnessed to reduce the emissions. Besides, the findings also validate the environmental Kuznets curve and pollution haven hypotheses in the context of Oman. Hence, considering these key findings, it is recommended that Oman should ideally pursues green economic growth policies by restricting inflows of unclean foreign direct investments and green its financial sector in order to collectively minimize its carbon dioxide emission figures.
Show more [+] Less [-]Potencies of organotin compounds in scallop RXRa responsive activity with a GAL4-based reconstituted yeast assay in vitro Full text
2022
Zhao, Anran | Miao, Jingjing | Liu, Liru | Pan, Luqing
Retinoid X receptor (RXR) has been found to be a major target in various processes of endocrine disruption from the exposure to organotin compounds (OTCs), including imposex in gastropod mollusks. It was also reported in bivalves that OTCs caused intersex and skewed sex ratio. In order to evaluate the effect of these ligand-like OTCs, we constructed a reconstituted yeast system (CfRE system) based on GAL4 yeast two-hybrid principle using scallop Chlamys farreri retinoid X receptor (CfRXRa) and retinoid X response element (RXRE) to investigate the ligand-induced transactivation of CfRXRa. Responses of CfRXRa to 9-cis retinoic acid (9cRA) and tested four OTCs showed concentration-dependent response which is comparable with reported RXRa in vitro assay of human and gastropods. The detective limits of the CfRE system were found to be 100 nM for 9cRA and 10–1000 nM for the tested OTCs. While the tested non-Sn endocrine disrupting chemicals, including Benzo[a]pyrene, 2,4-Dichlorophenol, Nonylphenol, and Tetrabromobisphenol A, showed no effect on CfRXRa response. The present assay system may provide a valuable tool for screening assessments of unidentified environmental ligand chemicals on bivalve mollusks. It is also useful for comparison of sensitivity differences among species exposed to EDCs.
Show more [+] Less [-]The asymmetric effect of environmental policy stringency on CO2 emissions in OECD countries Full text
2022
Albulescu, Claudiu Tiberiu | Boatca-Barabas, Maria-Elena | Diaconescu, Andra
This paper uses a quantile fixed-effect panel data approach to investigate how environmental policy stringency affects CO₂ emissions in a set of 32 countries from 1990 to 2015, using OECD data. This approach allows us to identify the asymmetric impact of policy stringency on emissions, considering the emission level recorded in each analysed country. More precisely, we posit that the effectiveness of environmental regulations and policies is influenced by the air pollution level. Our results show that an increase in policy stringency has a negative impact on emissions and that environmental stringency has a more powerful impact in the countries with lower levels of carbon emissions. In addition, we show that policy stringency measures only became effective after the implementation of the Kyoto agreement, whereas the policy stringency effect is stronger for EU countries at high risk of missing the 20–20-20 target in terms of greenhouse gas emissions. Lastly, policy implications refer to the need to adapt policy stringency measures to emission levels to increase their effectiveness. At the same time, the setting up of emission targets determines policymakers to be more engaged in the fight against carbon emissions.
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