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River health assessment of the Yellow River source region, Qinghai-Tibetan Plateau, China, based on tolerance values of macroinvertebrates Texte intégral
2019
Liu, Wei | Xu, Mengzhen | Zhao, Na | Zhou, Xiongdong | Pan, Baozhu | Tian, Shimin | Lei, Fakai
For decades, the river health of the Yellow River source region (YRSR) on the Qinghai-Tibetan Plateau has been a focal issue owing to its unique geographic location and ecological functions. This study investigated the ecological status of the headwater streams, the main stem, and the tributaries of the Yellow River in the YRSR using the tolerance values of macroinvertebrates and those related to biotic indices. The macroinvertebrate assemblages of the headwater streams were characterized by lower biodiversity than the tributaries downstream, based on comparisons of taxonomical composition, functional feeding group composition, and the pollution-tolerant capacity of taxa. The headwater streams had a lower ratio (16%) of pollution-sensitive macroinvertebrate taxa than that of the tributaries downstream (30%). The biotic indices (family- and genus-level biotic indices) indicated that the ecological health of the headwater streams was comparably poorer than that of the downstream tributaries. The combined effect of vulnerable natural conditions and increasing human disturbance is likely the main cause of eco-environmental degradation in the Yellow River headwater streams.
Afficher plus [+] Moins [-]Toxicological effects benzotriazole to the marine scallop Chlamys nobilis: a 2-month exposure study Texte intégral
2019
He, Tang-tian | Zhang, Tao | Liu, Shi-bo | Shi, Jing-chun | Huang, Yi-sheng | Zheng, Huai-ping | Liu, Wenhua
Benzotriazole and its associated derivatives (BTs) are widely used as ultraviolet stabilizers and corrosion inhibitors. They have been extensively found in marine environments and are bioaccumulative through the food chain. However, the toxicities of BTs to marine organisms are seldom identified and no assessment has been conducted for filter-feeding bivalves. In this study, a marine scallop Chlamys nobilis was exposed to 0, 0.01, 0.1, and 1.0 mg/L of BT for 60 days. Effects of BT on endocrine system, cytochrome P450 activity, antioxidant activity, and neural activity of C. nobilis were examined. The results showed that BT exerted significant estrogenic effects on both male and female scallops and inhibited EROD activities of C. nobilis even at 0.01 mg/L level. BT at ≥ 0.01 mg/L levels also caused significant oxidative stress on C. nobilis. Moreover, most of the adverse effects of BT to C. nobilis were found from day 35 and 0.01 mg/L was the lowest concentration with observed effects, showing the long-term toxic effects of BT to C. nobilis. Thus, the adverse effects of BT and its derivatives to marine benthic communities deserve more attention in future research.
Afficher plus [+] Moins [-]The effect of command-and-control regulation on environmental technological innovation in China: a spatial econometric approach Texte intégral
2019
Li, Wanhong | Gu, Yue | Liu, Fang | Li, Ce
Combining with the spatial variations in environmental technological innovation cross-province in China, this study employs the spatial econometric model to explore how environmental technological innovation responds to changes in command-and-control regulation and three other traditional determinants (the environmental R&D investments, the environmental labor force inputs, and the provincial economic development level) during the study period from 2004 to 2016.The results indicate that there is a clear sign of spatial correlation in the environmental technological innovation according to the global and local indicators of spatial association. Then, considering the spatial interdependence of environmental technological innovation and holding other variables constant, evidence shows that command-and-control regulation has a significant adverse effect on environmental technological innovation in the whole country and the Eastern region, while the effect is statistically positive in the Western region and non-significant in the Central region. We also find that the effects in two sub-periods of 2004–2010 and 2011–2016 are obvious differences because some new command-and-control regulation instruments were formulated and implemented in 2010. In addition, environmental technological innovation is also directly catalyzed by the environmental R&D investments, the environmental labor force inputs, and the provincial economic development level.
Afficher plus [+] Moins [-]Combined effects of coagulation and adsorption on ultrafiltration membrane fouling control and subsequent disinfection in drinking water treatment Texte intégral
2019
Xing, Jiajian | Liang, Heng | Cheng, Xiaoxiang | Yang, Haiyan | Xu, Daliang | Gan, Zhendong | Luo, Xinsheng | Zhu, Xuewu | Li, Guibai
This study investigated the combined effects of coagulation and powdered activated carbon (PAC) adsorption on ultrafiltration (UF) membrane fouling control and subsequent disinfection efficiency through filtration performance, dissolved organic carbon (DOC) removal, fluorescence excitation-emission matrix (EEM) spectroscopy, and disinfectant curve. The fouling behavior of UF membrane was comprehensively analyzed especially in terms of pollutant removal and fouling reversibility to understand the mechanism of fouling accumulation and disinfectant dose reduction. Pre-coagulation with or without adsorption both achieved remarkable effect of fouling mitigation and disinfection dose reduction. The two pretreatments were effective in total fouling control and pre-coagulation combined with PAC adsorption even decreased hydraulically irreversible fouling notably. Besides, pre-coagulation decreased residual disinfectant decline due to the removal of hydrophobic components of natural organic matters (NOM). Pre-coagulation combined with adsorption had a synergistic effect on further disinfectant decline rate reduction and decreased total disinfectant consumption due to additional removal of hydrophilic NOM by PAC adsorption. The disinfectant demand was further reduced after membrane. These results show that membrane fouling and disinfectant dose can be reduced in UF coupled with pretreatment, which could lead to the avoidance of excessive operation cost disinfectant dose for drinking water supply.
Afficher plus [+] Moins [-]Persulfate activation with rice husk-based magnetic biochar for degrading PAEs in marine sediments Texte intégral
2019
Dong, Cheng-Di | Chen, Chiu-Wen | Hung, Chang-Mao
Phthalate esters (PAEs) can interfere with the endocrine systems of humans and wildlife. The main objective of this study was to evaluate the suitability of a composite for remediating marine sediments contaminated with PAEs. The composite was synthesized with magnetite nanoparticles (Fe₃O₄) and rice husk biochar (RHB) by using chemical co-precipitation. Fe₃O₄, RHB, and Fe₃O₄–RHB substantially activated sodium persulfate (Na₂S₂O₈, PS) oxidation to form SO₄⁻• and thus degrade PAEs in marine sediments in a slurry system. The morphology and structural composition of the magnetic composites were examined using XRD, FTIR, environmental scanning electron microscopy–energy-dispersive X-ray spectrometry, and superconducting quantum interference device. The Fe₃O₄–RHB composites were confirmed to be prepared successfully. The influences of various parameters, including the PS concentration, composite loading, and initial pH, were investigated. The concentration of high-molecular-weight PAEs (HPAEs) in sediment was much higher than that of low-molecular-weight PAEs (LPAEs); di-(2-ethylhexyl) phthalate (DEHP) was an especially salient marker of PAE contamination in sediments. Furthermore, increasing the PS and Fe₃O₄–RHB doses accelerated PAE oxidation at pH 3.0; 83% degradation of PAEs was achieved when the PS and Fe₃O₄–RHB concentrations were increased to 2.3 × 10⁻² mM and 1.67 g/L, respectively. LPAEs such as dibutyl phthalate (DnBP) are easier to degrade than HPAEs such as DEHP, diisononyl phthalate (DINP), and diisodecyl phthalate (DIDP). In addition, possible activation mechanisms of the interactions between S₂O₈²⁻ and Fe²⁺/Fe³⁺ on the Fe₃O₄ surface, which involve an efficient electron transfer mediator of the RHB oxygen functional groups promoting the generation of SO₄⁻• in the Fe₃O₄–RHB/PS system, were clarified. Thus, the Fe₃O₄–RHB/PS oxidation process is expected to be a viable method for remediating PAE-contaminated marine sediment.
Afficher plus [+] Moins [-]Differentially expressed circular RNAs in air pollution–exposed rat embryos Texte intégral
2019
Li, Zheng | Ma, Jianqing | Shen, Jianxiong | Chan, Matthew T. V. | Wu, William K. K. | Wu, Zhanyong
Circular RNAs (circRNAs) are an important class of non-coding RNAs partly by acting as microRNA sponges. Growing evidence indicates that air pollution exposure during pregnancy could lead to congenital defects in the offspring. In this study, using circRNAs sequencing, we profiled differentially expressed circRNAs in rat embryos exposed to a high concentration (> 200 μg/m³) of fine particulate matter (PM₂.₅) in utero. Compared with the control embryos whose mothers were reared in clean air, 25 and 55 circRNAs were found to be downregulated and upregulated, respectively, in the air pollution–exposed group. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of circRNA-coexpressed genes indicated that segmentation, brain development, and system development together with lysine degradation, Rap1 signaling pathway, and adrenergic signaling were deregulated by in utero air pollution exposure. We also identified the central role of three circRNAs, namely circ_015003, circ_030724, and circ_127215 in the circRNA-microRNA interaction network. These data suggested that circRNA deregulation might play a crucial role in the development of air pollution–associated congenital malformations.
Afficher plus [+] Moins [-]Droplet flow-assisted heterogeneous electro-Fenton reactor for degradation of beta-blockers: response surface optimization, and mechanism elucidation Texte intégral
2019
Nsubuga, Hakimu | Basheer, Chanbasha | Jalilov, Almaz | Haider, Muhammad Baseer | Al-Saadi, Abdulaziz A.
In this study, we report an effective degradation method for trace level beta-blockers (propranolol and acebutolol) in hospital wastewater using a new droplet flow-assisted heterogeneous electro-Fenton reactor (DFEF) system. Biogenic iron–carbon nanocomposites (RHS/C-x% Fe) as eco-friendly and low-cost heterogeneous Fenton catalysts were synthesized from rice husk via hydrolytic sol–gel routes. Here, we demonstrate the use of natural air as a nebulizing agent for fast and continuous catholyte air saturation and Fenton catalyst transfer to the cathode electrode. The effects of key operational parameters were evaluated and optimized using central composite design. Results clearly indicated that enhanced beta-blocker degradation was mainly dependent on the interactive effects of electrolysis time, current density, and catalyst dosage. Fast degradation efficiencies (≥ 99.9%) was recorded at neutral pH conditions. The decay followed pseudo-first-order kinetics with degradation rates of up to 2.72 × 10⁻² and 2.54 × 10⁻² min⁻¹ for acebutolol and propranolol, respectively. The synergistic contribution of •OHbᵤₗₖ attributable to DFEF process and •OHₐdₛₒᵣbₑd for anodic oxidation (AO) at the anode electrode significantly enhanced the degradation process. Compared to AO, the conventional flow-assisted electro-Fenton (FEF), and the batch electro-Fenton (BEF), DFEF degradation efficiency followed a decreasing order: DFEF ˃ FEF ˃ BEF˃ AO. This trend in performance was mainly due to the fast and continuous cathodic electro-generation of H₂O₂ and Fe²⁺ regeneration. Additionally, in order to elucidate degradation mechanism, we used a combination of DFEF approach with liquid chromatography-tandem mass spectrometry analysis. This approach demonstrates a simple, cleaner, and highly efficient degradation approach for trace level recalcitrant pollutants in a complex aquatic matrix, without the need for external chemical addition and pH adjustment.
Afficher plus [+] Moins [-]The environmental impacts of financial development in OECD countries: a panel GMM approach Texte intégral
2019
Ganda, Fortune
Financial development is often expressed as a private sector initiative earmarked towards motivating economic growth and mitigating poverty. Nonetheless, the need for economic development accompanied by high industrialisation and commercialisation strategies has generated natural environmental effects which have raised enormous concern to green interest groups about whether all the seventeen sustainable development goals will be achieved. This paper investigated the environmental effects of financial development in OECD countries from 2001 to 2012 by employing static models and system GMM analysis. The study utilised foreign direct investments, domestic credit to private sector by banks and domestic credit to private sector as the three proxies of financial development. The effects of these measures of financial development were examined on carbon emissions and greenhouse gases (indicators of environmental quality) and environmental sustainability. In this setting, the findings of the research spotlight that domestic credit to private sector by banks shows a negative and significant relationship with carbon emissions, greenhouse gases and sustainability. Conversely, domestic credit to private sector and economic growth indicates a positive and statistically significant relationship with carbon emissions, greenhouse gases and sustainability. Foreign direct investment is positive and significantly connected with carbon emissions and sustainability but only shows a positive and not significant link with greenhouse gases. The evidence suggested by this analysis adds that the financial system should continue to add more initiatives which consider natural environmental perspectives in their current operations. This present study also confirms the existence of the environmental Kuznets curve (EKC) in carbon emissions (turning point, $109,820), total greenhouse gases (turning point, $74,280) and sustainability (turning point, $112,505). The finding that the turning point of carbon emissions is higher than that of total greenhouse gases indicates why introducing initiatives designed to curb growth of carbon emissions in the respective OECD economies is important.
Afficher plus [+] Moins [-]Ambient air pollution and the risk of stillbirth: a population-based prospective birth cohort study in the coastal area of China Texte intégral
2019
Zang, Hongyan | Cheng, Han | Song, Wenya | Yang, Mei | Han, Ping | Chen, Chunxiao | Ding, Rui
Accumulating evidence has shown that prenatal ambient air pollution exposure is associated with elevated stillbirth risk; however, the results are inconsistent. This population-based prospective cohort study aimed to explore the association between prenatal air pollution exposure and stillbirth rate in the coastal area in China. Data of air pollution and birth outcomes between January 1, 2015, and December 31, 2017, were collected. Among the 59,868 eligible births, there were 587 stillbirths and 59,281 live births. Although the air quality in this study was relatively better than most of the major cities in China, a positive association was still found between prenatal air pollution exposure and stillbirth rate. Every 10 μg/m³ increase of fine particulate matters (PM₂.₅) in each trimester, as well as in the entire pregnancy, was associated with increased stillbirth rate (RR = 1.14, 1.11, 1.15, and 1.14 for the first, second, third trimester, and entire pregnancy, respectively). In addition, every 10 μg/m³ increase of PM₁₀ in the first trimester (RR = 1.09, 95% CI: 1.04–1.14), and 10 μg/m³ increase of O₃ in the first (RR = 1.05, 95% CI: 1.01–1.09) and third (RR = 1.04, 95% CI: 1.00–1.08) trimesters was also associated with increased stillbirth rate. The effects of PM₂.₅ on stillbirth rate were found to be robust in the two-pollutant models. The findings of this study especially underscored the adverse effects of prenatal exposure of high levels of PM₂.₅ on stillbirth. More studies are needed to verify our findings and further investigate the underlying mechanisms.
Afficher plus [+] Moins [-]Ecological and human health risk assessment of heavy metal contamination in road dust in the National Capital Territory (NCT) of Delhi, India Texte intégral
2019
Roy, Sayantee | Gupta, Sanjay Kumar | Prakash, Jai | Habib, Gazala | Baudh, Kuldeep | Nasr, Mahmoud
The present study was carried out to determine the contamination levels of heavy metals in road dust of the National Capital Territory of Delhi (NCT), India and its consequent effect on human and environment. The levels of heavy metals (Pb, Zn, Cu, Cr, Ni, Mn, and Fe) in 9 districts (Z1–Z9) of NCT were monitored and the corresponding human health risk was estimated. District-wise evaluation of heavy metal pollution in the road dust was performed. The mean concentrations of Pb, Zn, Cu, Ni, Cr, Mn, and Fe in the road dust samples over the study area were 164.2 ± 53.2, 200.7 ± 45.3, 99.9 ± 64.8, 24.7 ± 5.7, 57.7 ± 25.9, 241.4 ± 39.8, and 11113.9 ± 1669.7 mg kg⁻¹, respectively. PLI showed a high pollution load in the monitored nine locations, indicating an alarming condition and the urgent need for immediate remedial actions. Ecological risk assessment depicted that a 74% risk was attributed to Pb. Hazard quotient (HQ) values indicated that ingestion was the major pathway of road dust heavy metal exposure to human beings. Hazard index values showed that there was no probable non-carcinogenic risk of the heavy metals present in the road dust of the area. Children were found vulnerable to the risks of road dust metals. The findings of this study showed the alarming status of heavy metal contamination to road dust in NCT and the associated risk to human health.
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