细化搜索
结果 1341-1350 的 6,548
Sources and spatio-temporal distribution of aerosol polycyclic aromatic hydrocarbons throughout the Tibetan Plateau 全文
2020
Zheng, Huijun | Kang, Shichang | Chen, Pengfei | Li, Quanlian | Tripathee, Lekhendra | Maharjan, Linda | Guo, Junming | Zhang, Qianggong | Santos, Ewerton
With the recent rapid development of urbanization, atmospheric pollutants such as polycyclic aromatic hydrocarbons (PAHs) have attracted wide attention, particularly in remote regions. The Tibetan Plateau (TP), known as the third pole is adjacent to areas with heavy atmospheric pollution, such as South and East Asia. However, the spatial distribution and sources of PAHs on the TP remain unclear. Thus, we investigated the sources and spatio-temporal distributions of PAHs on the TP by combining aerosol sample data from six sites, including Ngari (NG), Laohugou (LHG), Beiluhe (BLH), Nam Co (NMC), Everest (EV), and Yulong (YL), in 2014 and 2016. The average concentrations of 15 PAHs at the six sites ranged from 3.4 to 15.2 ng m⁻³, with a decreasing trend from the marginal to inner areas of the plateau. The highest concentration was that in YL in the southeastern part of the TP, with an average of 15.2 ng m⁻³. The PAH concentrations in NG, NMC, and YL were higher in autumn and winter and lower in summer. High molecular weight PAHs usually exists in the particulate phase whereas tricyclic PAHs can change from particulate to gaseous phase, therefore it can indicate long-range transport. Tricyclic PAHs were the dominant PAHs on the TP (44%–58%), indicating long-range atmospheric transport as the major source of PAHs. Principal component analysis (PCA) and diagnostic ratio analysis showed that biomass and coal combustion were the major sources of PAHs in inland areas of the TP; however, marginal plateau areas were affected by fossil fuel emissions. Compared with levels in Beijing and other urban sites, the toxic equivalent quantity (TEQ) was low (0.36–1.06 ng m⁻³), suggesting a low risk to human and ecosystem health.
显示更多 [+] 显示较少 [-]Microbial community evolution during the aerobic biodegradation of petroleum hydrocarbons in marine sediment microcosms: Effect of biostimulation and seasonal variations 全文
2020
Hamdan, Hamdan Z. | Salam, Darine A.
Evolution of the microbial community structure in crude oil contaminated marine sediments was assessed under aerobic biodegradation during wet (18 °C) and dry (28 °C) seasons experiments, to account for seasonal variations in nutrients and temperature, under biostimulation and natural attenuation conditions. NMDS showed significant variation in the microbial communities between the wet and the dry season experiments, and between the biostimulation and the natural attenuation treatments in the dry season microcosms. No significant variation in the microbial community and oil biodegradation was observed during the wet season experiments due to high background nitrogen levels eliminating the effect of biostimulation. Larger variations were observed in the dry season experiments and were correlated to enhanced alkanes removal in the biostimulated microcosms, where Alphaproteobacteria dominated the total microbial community by the end of biodegradation (54%). Many hydrocarbonoclastic bacterial genera showed successive dominance during the operation affecting the ultimate performance of the microcosms.
显示更多 [+] 显示较少 [-]Composition characterization and biotransformation of dissolved, particulate and algae organic phosphorus in eutrophic lakes 全文
2020
Feng, Weiying | Yang, Fang | Zhang, Chen | Liu, Jing | Song, Fanhao | Chen, Haiyan | Zhu, Yuanrong | Liu, Shasha | Giesy, John P.
Characteristics and transformation of organic phosphorus in water are vital to biogeochemical cycling of phosphorus and support of blooms of phytoplankton and cyanobacteria. Using solution ³¹P nuclear magnetic resonance (NMR), combined with field surveys and lab analyses, composition and structural characteristics of dissolved phosphorus (DP), particulate phosphorus (PP) and organic P in algae were studied in two eutrophic lakes in China, Tai Lake and Chao Lake. Factors influencing migration and transformation of these constituents in lake ecosystems were also investigated. A method was developed to extract, flocculate and concentrate DP and PP from lake water samples. Results showed that orthophosphate (Ortho-P) constituted 32.4%–81.3% of DP and 43.7%–54.9% of PP, respectively; while monoester phosphorus (Mono-P) was 13.2%–54.0% of DP and 32.9%–43.7% of PP, respectively. Phosphorus in algae was mostly organic P, especially Mono-P, which was ≥50% of TP. Environmental factors and water quality parameters such as temperature (T), electrical conductivity (EC), pH, secchi depth (SD), dissolved oxygen (DO), chemical oxygen demand (CODcᵣ), chlorophyll-a (Chl-a), affected the absolute and relative concentrations of various P components in the two lakes. Increased temperature promoted bioavailable P (Ortho-P and Mono-P) release to the lake waters. The results can provide an important theoretical basis for the mutual conversion process of organic P components between various media in the lake water environment.
显示更多 [+] 显示较少 [-]Biological effects from environmental pollution by toxic metals in the “land of fires” (Italy) assessed using the biomonitor species Lunularia cruciata L. (Dum) 全文
2020
Maresca, Viviana | Sorbo, Sergio | Loppi, Stefano | Funaro, Federica | Del Prete, Davide | Basile, Adriana
The liverwort Lunularia cruciata was collected from the town of Acerra, in the heart of the so-called ‘Land of Fires’ a large area in the eastern part of Campania region of Italy affected by burning of waste and fraudulent dumping and one of the vertices of the “Italian Triangle of Death” so said for the high incidence and mortality from tumors. The data obtained from these samples were compared with samples collected in two other sites representing two different environmental conditions. The soil below the samples, and gametophytes, were collected and analyzed for the concentration of Al, As, Ba, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, V. DNA damage, Reactive Oxygen Species production and localization, activity of antioxidant enzymes and presence of chelating molecules were investigated. All biomarkers provided an answer closely related to the pollution conditions at the 3 sites. We discuss the data considering the possibility of using these biological changes as environmental pollution biomarkers. Finally, it is underlined the importance of phytochelatins due to of their specificity for metal pollution.
显示更多 [+] 显示较少 [-]China is implementing “Garbage Classification” action 全文
2020
Tong, Yeqing | Liu, Jiafa | Liu, Sizhe
In recent days, garbage classification has become a hot topic in China, and Shanghai took the lead in the implementation of garbage classification legislation in China. Starting from the current situation of garbage classification in China, this study emphasizes the garbage classification in terms of law, amount, economy, management, resourcing and successful experience of garbage classification in China, so as to provide inspiration and guidance for garbage classification for other countries.
显示更多 [+] 显示较少 [-]Distribution of organophosphate esters between the gas phase and PM2.5 in urban Dalian, China 全文
2020
Wang, Yan | Bao, Meijun | Tan, Feng | Qu, Zhenping | Zhang, Yuwei | Chen, Jingwen
We investigated the concentrations and seasonal variations of organophosphate esters (OPEs) in the gas phase and PM₂.₅ (particulate matter with an aerodynamic diameter <2.5 μm) in an urban area of Dalian, China, as well as their gas-particle partitioning. The total concentrations of OPEs in the gas phase were in the range of 0.056–6.38 ng/m³ with the mean concentration of 0.83 ± 1.24 ng/m³, while the concentrations of OPEs in the PM₂.₅ were in the range of 0.32–3.46 ng/m³ with the mean concentration of 1.21 ± 0.67 ng/m³. Tris-(1-chloro-2-propyl) phosphate (TCIPP) was the dominant congener in the gaseous phase, followed by tris-(2-chloroethyl) phosphate (TCEP) and tri-n-butylphosphate (TNBP), whereas TCEP was the dominant species in the PM₂.₅, followed by TCIPP and triphenyl phosphate (TPHP). Seasonality was discovered for OPEs in both gas phase and PM₂.₅ with their concentrations higher in hot seasons, which may due to the temperature-driven emission or gas-particle partitioning. The PM₂.₅-bound fractions of OPEs varied significantly between seasons. Tricresyl phosphate (TMPP), tri(2-ethylhexyl) phosphate (TEHP), 2-ethylhexyl diphenyl phosphate (EHDPP), and TPHP were mostly adsorbed onto fine particles, while TNBP, TCEP, TCIPP, and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) distributed in both gas and fine particle phases. The predicted PM₂.₅-bound fractions by Kₒₐ-based model were closer to the measurements for TCIPP, TDCIPP, and TPHP, whereas the predictions by Junge-Pankow model were closer to the measurements for TMPP and tris (2-butoxyethyl) phosphate (TBOEP). However, the predictions of both models cannot accurately match the measured gas-particle partitioning of TNBP and TCEP.
显示更多 [+] 显示较少 [-]Contrasting temporal dynamics of dissolved and colloidal trace metals in the Pearl River Estuary 全文
2020
Xie, Minwei | Wang, Wen-Xiong
Metal contamination in the Pearl River Estuary (PRE) is persistent-, yet a comprehensive understanding of distribution and behavior of metals in surface water of this large, multi-source estuary is still lacking. In the present study, water samples from 24 sites spanning the whole estuary during the dry and wet season were collected and fractioned. Trace metal concentrations in samples were then determined following a preconcentration technique using Nobias Chelate-PA1 resin. Distribution of trace metals exhibited variability along and across estuary, as a result of estuarine mixing, external metal loadings, addition and removal. Behavior of metals was contrasting between the dry and wet seasons, exhibiting metal-specific intercorrelations and dynamics. Colloidal metals (Mn, Ni and Cd) were primarily present in upper estuary and areas affected by external contaminant loading. Colloidal Cu was the only metal that was ubiquitous in the estuary in both seasons. It showed a high affinity for small-size organic colloids (likely fulvic acid) during the dry season. Overall, the present study demonstrated the multi-source character of the PRE and that the behavior of trace metals was controlled by the coupling of hydrologic and geochemical processes, with anthropogenic perturbations.
显示更多 [+] 显示较少 [-]Silica nanoparticles induce spermatogenesis disorders via L3MBTL2-DNA damage-p53 apoptosis and RNF8-ubH2A/ubH2B pathway in mice 全文
2020
Liu, Jianhui | Li, Xiangyang | Zhou, Guiqing | Sang, Yujian | Zhang, Yue | Zhao, Yanzhi | Ge, Wei | Sun, Zhiwei | Zhou, Xianqing
Silica nanoparticles (SiNPs) can reduce both quality and quantity of sperm via inhibiting the progress of meiosis and mitosis and inducing apoptosis of spermatogenic cells, however, their specific mechanism and effects on the later stage of spermatogenesis are still unclear. To investigate the effects of SiNPs on the reproductive system, male mice were treated with SiNPs (0, 1.25, 5 and 20 mg/kg.bw) via intratracheal instillation once every 3 days and for a total of 15 days. Results revealed that exposure to SiNPs induced reduction in the rate of sperm activity, histological abnormalities in seminiferous epithelium as well as apoptosis of spermatogenic cells, which are associated with decreased level of Lethal (3) malignant brain tumor like 2 (L3MBTL2) and activation of DNA damage-p53-mitochondrial apoptosis pathways. Moreover, reduction in L3MBTL2 level caused by SiNPs also led to the lower expression of RNF8-ubH2A/ubH2B pathway, thus resulting in incomplete histone-to-protamine exchange. These results suggest that the inhibition of L3MBTL2 expression caused by SiNPs not only activates DNA damage-p53-mitochondrial apoptosis pathway leading to the apoptosis of spermatogenic cells, but also inhibits RNF8-ubH2A/ubH2B pathway resulting in incomplete histone-to-protamine exchange, thereby affected spermatogenesis. This indicates that L3MBTL2 plays an important role in reproductive toxicity of males caused by SiNPs.
显示更多 [+] 显示较少 [-]Personal exposure to fine particulate matter and renal function in children: A panel study 全文
2020
Liu, Miao | Guo, Wenting | Cai, Yunyao | Yang, Huihua | Li, Wenze | Yang, Liangle | Lai, Xuefeng | Fang, Qin | Ma, Lin | Zhu, Rui | Zhang, Xiaomin
There is a lack of evidence regarding the association of short-term exposure to fine particulate matter (PM₂.₅) with renal function in children and its underlying mechanism. We included 105 children aged 4–13 years from a panel study conducted in Wuhan, China with up to 3 repeated visits across 3 seasons from October 9, 2017 to June 1, 2018. We measured personal real-time PM₂.₅ exposure concentration continuously for 72 h preceding each round of health examinations that included serum creatinine and cytokines. Linear mixed-effects models were performed to estimate the effects of PM₂.₅ on estimated glomerular filtration rate (eGFR) over various lag times, and a mediation analysis was applied for the role of cytokines in association between PM₂.₅ and eGFR. Results showed that personal exposure to PM₂.₅ was dose-responsive related to decreased eGFR within lag 2 days. The effect was the strongest at lag 0 day with estimation of −1.69% [95% confidence interval (CI): -2.27%, −1.10%] in eGFR by a 10-μg/m³ increase in PM₂.₅, and reached peak at lag 3 h, then declined over time. Such inverse relationships were more evident among children aged 4–6 years, or boys or those who lived proximity to major roadways <300 m. Notably, eGFR still held on to decrease even when PM₂.₅ was below Class II Chinese ambient air quality standard at lag 0 day. Moreover, the effect of PM₂.₅ on eGFR was significantly reduced in children with high and medium levels of serum chemokine ligand 27 (CCL27), but not in those with low CCL27. Furthermore, CCL27 was positively relevant to PM₂.₅, and mediated proportion of CCL27 ranged from 3.75% to 6.61% in relations between PM₂.₅ and decreased eGFR over various lag times. In summary, short-term PM₂.₅ exposure might be dose-responsive associated with reduced eGFR whereby a mechanism partly involving CCL27 among healthy children.
显示更多 [+] 显示较少 [-]Effect of biochar modified with magnetite nanoparticles and HNO3 for efficient removal of Cr(VI) from contaminated water: A batch and column scale study 全文
2020
Imran, Muhammad | Khan, Zia Ul Haq | Iqbal, Muhammad Mohsin | Iqbal, Jibran | Shah, Noor Samad | Munawar, Saba | Ali, Shafaqat | Murtaza, Behzad | Naeem, Muhammad Asif | Rizwan, Muhammad
Chromium (Cr) poses serious consequences on human and animal health due to its potential carcinogenicity. The present study aims at preparing a novel biochar derived from Chenopodium quinoa crop residues (QBC), its activation with magnetite nanoparticles (QBC/MNPs) and strong acid HNO₃ (QBC/Acid) to evaluate their batch and column scale potential to remove Cr (VI) from polluted water. The QBC, QBC/MNPs and QBC/Acid were characterized with SEM, FTIR, EDX, XRD as well as point of zero charge (PZC) to get an insight into their adsorption mechanism. The impact of different process parameters including dose of the adsorbent (1–4 g/L), contact time (0–180 min), initial concentration of Cr (25–200 mg/L) as well as solution pH (2–8) was evaluated on the Cr (VI) removal from contaminated water. The results revealed that QBC/MNPs proved more effective (73.35–93.62-%) for the Cr (VI) removal with 77.35 mg/g adsorption capacity as compared with QBC/Acid (55.85–79.8%) and QBC (48.85–75.28-%) when Cr concentration was changed from 200 to 25 mg/L. The isothermal experimental results follow the Freundlich adsorption model rather than Langmuir, Temkin and Dubinin-Radushkevich adsorption isotherm models. While kinetic adsorption results were well demonstrated by pseudo second order kinetic model. Column scale experiments conducted at steady state exhibited excellent retention of Cr (VI) by QBC, QBC/MNPs and QBC/Acid at 50 and 100 mg Cr/L. The results showed that this novel biochar (QBC) and its modified forms (QBC/Acid and QBC/MNPs) are applicable with excellent reusability and stability under acidic conditions for the practical treatment of Cr (VI) contaminated water.
显示更多 [+] 显示较少 [-]