The coincidence and superposition of flood processes from different rivers and regions tend to form compound flood events, determined by spatial relationship between diverse flood processes that ...cannot be accurately depicted and evaluated by existing dependence analysis methods. A framework, integrating multi‐dimensional vine copula model and dependence evaluation system, was developed with a testing‐oriented application to explore underlying dependence between two kinds of extreme runoff series (peak discharge and flood volume) extracted from the identified compound flood events in the upper reaches of the Yangtze River. Multi‐dimensional regular vine (R‐vine) copula models were established to depict the complex and diverse dependence, and corresponding vine structure was specified by the vine structure array that can reflect the sequence of tributaries flowing into the main stream and the spatial locations of different hydrometric stations. Dependence magnitude and association status were calculated and compared according to the optimal R‐vine copula models and information theory. Comparison with existing methods demonstrated that dependence evaluation system could reflect nonlinear and local dependence characteristics and eliminate the effect of extreme runoff series from other hydrometric station on the dependence. The association status between different extreme runoff series of the upper Yangtze River and its tributaries were diverse in view of the impact of tributary flood inflow. The proposed framework can be regarded as an effective way for dependence modeling and evaluation of compound floods, thus providing a scientific reference for the risk analysis of water resources systems.
Key Points
Vine structure is specified by the sequence of tributaries flowing into main stream and spatial locations of hydrological stations
Dependence evaluation system determines dependence magnitude and association status through R‐statistic and interaction gain
Extreme runoff series of the same hydrometric station show distinct association status
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Riverine water temperature (WT) is a crucial factor affecting habitat quality and ecological effect of aquatic ecosystems. To accurately quantify and classify WT variation features caused by climate ...change and reservoir construction and operation, a framework was developed that integrates multivariate vine copula model for accurately reconstructing the WT process and general evaluation indicators for comprehensively characterizing of WT variation. In this framework, month‐wise R‐vine copula models were employed to depict the multivariate dependence structure between WT and related hydrometeorological factors, and the change of WT process in the fluctuation range and thermal deviation was analogized as the change of simple harmonic wave in amplitude and phase. A testing‐oriented application of this framework in Yichang section of the Yangtze River highlighted that climate change and the Three Gorges Reservoir (TGR) dominated or participated in the fluctuation range changing and phase deviation of different monthly WT processes, as the ratios of affected months were 1.08:1 and 1.25:1 during the construction phase, and 1:2 and 1:1.28 during the operation phase. WT process also exhibited diverse monthly variation trends during construction and operation phases of the TGR. Therefore, it is inappropriate to neglect the impact of the TGR construction phase and climate change on WT variation. The proposed framework achieved systematic quantification and attribution analysis of WT variation, thereby providing an enhanced understanding of the variation characteristics of river thermal regimes under the individual and combined effects of climate change and artificial reservoir. Considering the significant influence of WT variation on aquatic organism reproduction, the identification of the sources and categories of monthly WT variation can also serve as a foundation for future targeted thermal and hydrological regime regulation, aiming to protecting aquatic species and preventing biodiversity loss.
The testing‐oriented application of this framework achieved a truly quantitative evaluation for the impact of the Three Gorges Reservoir (TGR) and climate change on downstream water temperature (WT) variation features, thus demonstrating its high reliability and practicability. It is inappropriate to neglect the impact of climate change and reservoir construction on WT variation because the TGR and climate change dominate or participate in different monthly WT variation features, and WT variation appears complex and opposite characteristics during the construction and operation phases of the TGR.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
A coupled modelling framework, consisting of the storm surge model and the European Regional Seas Ecosystem Model (ERSEM), has been established to examine hydrodynamics process during Typhoon Hagupit ...and its role on nutrient and salinity dynamics in the Pearl River Estuary (PRE). The accuracy of modelling framework was reasonably validated against measured typhoon wind, storm tide, and water quality data. Further analysis suggests Hagupit significantly increases water levels in the PRE. Meanwhile, the seaward residual currents apparently and chaotically change. The phosphate and dissolved inorganic nitrogen concentrations decrease by 0.2–1.8 and 20–88.6 μmol/L in the most area from the downstream of narrow river channels to offshore region due to the variations of hydrodynamics, while small difference was detected in upstream narrow channels and open sea. By contrast, salinity distribution showed opposite variation. Statistically, the typhoon winds alleviated the averaged nutrient pollution in the whole PRE, while causing serious saltwater intrusion.
•A coupled storm surge-water quality modelling framework is developed.•The accuracy of the coupled model is validated against in-situ measured data.•The hydrodynamics, nutrient and salinity dynamics during a typhoon are presented.•The study improves the understand of water environment evolutions during typhoons.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
To dynamically observe the levels and activities of von Willebrand factor (vWF) and ADAMTS-13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) in plasma of children ...with congenital ventricular septal defect (VSD) during perioperative period, and explore the value of plasma vWF antigen (vWF:Ag) and ADAMTS-13 activity (ADAMTS-13: AC) in evaluating vascular endothelial injury and prognosis in children with VSD.
In this cross-sectional study, a total of 74 children with VSD who underwent surgical treatment in TEDA International Cardiovascular Hospital from September 2018 to March 2019 were enrolled in the observation group. Among them, there were 28 cases of pure VSD, 32 cases of VSD combined with pulmonary hypertension, and 14 cases of VSD combined with valvular heart disease. 31 healthy children who underwent physical examination in Tianjin Children's Hospital during the same period were collected as the control group. The biochemical indexes of the children at admission were
•Complexing ligands had contrasting effect on Mn(II)/PMS and Mn(II)/PDS systems.•EDTA and NTA greatly enhanced the oxidation of contaminants in Mn(II)/PMS system.•Formation of Mn(III) species was an ...essential step for contaminants degradation.•Mn(V) but not free radicals was the dominant reactive oxidant.
In recent years, the activation of persulfates (peroxydisulfate (PDS) and peroxymonosulfate (PMS)) via transition metal ions for contaminants degradation has received extensive attention in water treatment. There has been growing interest on the mechanism (radical versus non-radical pathway) of activation processes. Interestingly, in contrast to copper, iron or cobalt ions regarded as effective activators for persulfates, manganese ion (Mn(II)) is inefficient for persulfates activation. Inspired by the enhanced stability of manganese species by ligands, this study for the first time systematically investigated the Mn(II)/persulfates with different ligands as a novel oxidation technology. UV-vis spectrometry, chemical probing method and mass spectrometry were used to explore the reactive intermediate (free radical versus high-valent manganese species) therein. It was surprisingly found that the oxidation efficiency of Mn(II)/ligand/persulfates system was highly dependent on the nature of persulfates and ligands. Mn(II) chelated by amino ligands such as ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetate (NTA) could efficiently trigger the oxidation of contaminants (e.g., recalcitrant compounds nitrophenol, benzoic acid and atrazine) by PMS, suggesting a promising Mn(II)/ligand/PMS technology for environmental decontamination especially under manganese-rich conditions. High-valent Mn species (Mn(V)) but not free radicals was demonstrated to be the dominant reactive intermediate, where Mn(III) species played a vital role in Mn(V) generation. The formation of Mn(III) species was found to be affected by the reactivity of persulfates and the type of ligands, thus influencing its further oxidation to Mn(V) species. This study presents a new oxidation process based on the combination of PMS and Mn(II) complex and broadens the knowledge of persulfates activation as well as manganese chemistry for decontamination in water treatment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•R-statistic is used in predictor variables selection and vine structure determination.•Stochastic simulation series preserve distribution and statistical characteristics of observed records.•The ...proposed approach has low sensitivity to the number of predictor variables.•The proposed approach possesses good adaptability and robustness.
Stochastic streamflow generation is crucial for water resources planning and management as well as water conservancy project design and operation. This study proposes an accurate, reliable and parsimonious approach for stochastic streamflow generation considering temporal and spatial dependence on the basis of regular vine copula model. The emphasis is on advancing an R-statistic based strategy of vine structure determination that divide the vine copula model construction into two independent parts and avoid continuous accumulation of uncertainty in the traditional Kendall's tau based method. Two study regions (the Upper Colorado River basin and Middle Yangtze River basin) with diverse hydrology regime and available data length are selected as case studies to showcase the performance of the proposed approach in practice. The results indicate better performance than two existing models in terms of streamflow estimation, and demonstrate that stochastic simulation series can preserve distribution and statistical characteristics of observed records. R-vine copula model constructed by the proposed approach is confirmed to possess low sensitivity to the number of predictor variables as well as good adaptability and robustness to streamflow series with diverse characteristics and abundances. The enhanced capability and performance stem from the accurate identification of predictor variables and characterization of complex and diverse dependence structures among different streamflow series, on the basis of a comprehensive and precise dependence measure, R-statistic.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Although health benefits of physical activity are well known, the risk of physical activity in polluted air is unclear. Our objective is to investigate health effects resulting from physical activity ...in polluted air by looking at particle deposition in human tracheobronchial (TB) airways. Airflow and particle deposition in TB airways were investigated using a computational fluid dynamics (CFD) method. We chose three regional airways: upper (G3–G5), central (G9–G11) and lower (G14–G16). Physical activity was described by breathing rate at the mouth, for three levels of activity: sedentary (15 l/min), moderate (30 l/min) and intense (60 l/min). We found that particle deposition was strongly affected by physical activity. Particles are deposited in greater number in the lower airways (G14–G16) during sedentary activity, more in the upper airways (G3–G5) during intense activity, and uniformly in the airways during moderate activity. The difference in the deposition pattern was due to the reason that physical activity increased the airflow which increased inertial impaction. Our modeling of particle deposition in the human respiratory airways shows that there are different health effects for different activity levels: sedentary activity leads to chronic health effects, intense activity results in acute effects, and moderate activity minimizes the adverse health effects of physical activity in polluted air.
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•Physical activity is generally good for health but increases exposure to air pollution.•We examined particle deposition in human airways for different levels of physical activity.•Inactivity increases particle deposition in lower airways resulting in chronic health effects.•Intense activity increases particle deposition in upper airways resulting in acute health effects.•We found health benefits of moderate activity when exposed to air pollution.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Relative contribution of high-valent iron species and SO4·- were quantitatively accessed.•Both high-valent iron species and SO4·- were involved in the Fe(VI)/sulfite system.•Only ...high-valent iron species was involved in the Fe(VI)/thiosulfate system.•The formation of 18O labeled PMSO2 in H218O was observed.•Effects of solution pH, oxygen and alcohols were investigated.
Recently, it has been reported that sulfur reducing agents (e.g., sulfite and thiosulfate) can effectively activate Fe(VI), leading to a fast degradation of various contaminants. However, the reactive intermediates (i.e., high-valent iron species versus free radicals) involved in the Fe(VI)/sulfite and Fe(VI)/thiosulfate systems remain far from clear. In this work, by using methyl phenyl sulfoxide (PMSO) as a mechanistic probe, we quantitatively assessed the relative contribution of high-valent iron species versus sulfate radical in these two systems. High-valent iron species oxidized PMSO to methyl phenyl sulfone product (PMSO2), while sulfate radical oxidized PMSO to hydroxylated and/or polymeric products. The yield of PMSO2 (mole of PMSO2 formed per mole of PMSO consumed) was quantified to be in the range of 30–95% under various conditions. This finding suggested the contribution of both high-valent iron species and sulfate radical in the Fe(VI)/sulfite system, which was dependent on solution chemistry (i.e., solution pH and Fe(VI):sulfite ratio). Comparatively, the yield of PMSO2 in the Fe(VI)/thiosulfate system remained as high as 90–100% under various conditions. This finding indicated that only high-valent iron species was involved in the Fe(VI)/thiosulfate system and the contribution of sulfate radical was negligible. The discrepancy in the effects of oxygen, alcohol scavenger and co-existing components (e.g., Cl−, HCO3−, and humic acid) on the Fe(VI)/sulfite versus Fe(VI)/thiosulfate systems also indicated the involvement of different oxidants in these two systems.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•TCs could be efficiently degraded by unactivated PMS.•Dimethylamino group and phenolic D ring of TCs were the main reaction sites.•Oxidation of TCs yielded O-addition, demethylation, ...and deamination products.•PMS oxidation could greatly eliminate the antibacterial activity of TCs.•Ca2+ and Mg2+ accelerated the oxidation of TCs by PMS due to their complexation effect.
Tetracyclines (TCs) as a group of widely used antibiotics are frequent detected in aqueous environments. The transformation of tetracycline (TTC), oxytetracycline (OTC), and chlorotetracycline (CTC) as model TCs by unactivated peroxymonosulfate (PMS) during water treatment is examined in this study for the first time. Degradation of TCs by PMS showed a strong pH-dependency. The apparent second-order rate constants were in the range of 0.07–150.10 M−1s−1 (pH 5.0–10.0). Products analysis showed that PMS primarily reacted with TCs at their unprotonated dimethylamino group and deprotonated phenolic-diketone group, leading to the formation of O-addition, demethylation, and deamination products. Water hardness Ca2+ and Mg2+ appreciably accelerated the degradation of TCs by PMS due to their strong complexation with TCs, while chloride, bicarbonate, and natural organic matter at environmental relevant concentrations had negligible impacts. Transformation products of TCs showed negligible antibacterial activity comparing with the parent TCs by using Escherichia coli. as test bacteria. The degradation of TCs by PMS in real waters was appreciably faster than that in pure water, and the presence of background Ca2+ and Mg2+ in real waters accounted for this enhancing effect. Unactivated PMS exhibits great potential for the removal of TCs and their antibacterial activity from contaminated waters.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Oxidation of LEV by unactivated PMS showed strong pH dependency.•In-situ formed MnO2 could activate Mn(VII) for the degradation of LEV.•LEV degradation in real waters by PMS and ...Mn(VII) was investigated.•Oxidation products exhibited much lower antibacterial activity than parent LEV.•The activation mechanisms of BQ for PMS and Mn(VII) were different.
Permanganate (Mn(VII)) as a selective oxidant has been widely used in water treatment process. Recently, peroxymonosulfate (PMS) was recognized as an emerging selective oxidant, which showed appreciable reactivity toward organic compounds containing electron-rich functional groups. In this study, the oxidation of a model fluoroquinolone antibiotic levofloxacin (LEV) by Mn(VII) and PMS was comparatively investigated. Degradation of LEV by PMS followed second-order kinetics and showed strong pH dependency with apparent second-order rate constants (kapp) of 0.15-26.52 M−1 s−1 at pH 5.0–10.0. Oxidation of LEV by Mn(VII) showed autocatalysis at pH 5.0–7.0, while no autocatalysis was observed at pH 8.0–10.0 (kapp = 2.23–4.16 M−1 s−1). Such unusual oxidation kinetics was attributed to the in-situ formed MnO2 from Mn(VII) consumption. The performance of PMS and Mn(VII) for the degradation of LEV was also examined in real waters. PMS primarily react with the aliphatic N4 amine on the piperazine ring of LEV, and Mn(VII) reacted with both the aliphatic N4 amine and aromatic N1 amine. Both PMS and Mn(VII) could efficiently eliminate the antibiotic activity of LEV. Benzoquinone showed activating effect on both PMS and Mn(VII) oxidation, but their activation mechanisms were totally different.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
