Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 102
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Water Res ; 211: 118045, 2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-35063928

RESUMO

Rational coastal groundwater planning is of great significance to freshwater supply for sustainable social-economic development, and to environmental protection in case of seawater intrusion (SI). Quantifying the relation among groundwater quality, quantity, and the related social-economic benefits in a coastal region with intense spatio-temporal variation in groundwater abstraction is helpful to the restoration of the coastal aquifer, and the practical policymaking. However, due to the comprehensive reality involving interdisciplinary principles, it is usually difficult to integrate all the main attributes of groundwater resources into a mono-policymaking process, which might lead to biased decisions, producing a series of adverse impacts on the environment and the social economy. This study thereby develops a combined simulation-optimization model (S-O model) in the coastal part of Longkou City, China, for striking the balance among the three main attributes of groundwater, i.e., the groundwater quantity, groundwater quality or its environmental function, and its related economic yield involving the agricultural and industrial sectors. It is seen that the industrial sector contributed over 80% of the economic yield by consuming over 10% of the total groundwater resource, and the massive agricultural use of groundwater was mainly responsible for the SI. The results of the multi-objective optimization provided practical alternative schemes for groundwater abstraction in terms of maximizing economic yield and minimizing SI. Moreover, the decision discrepancy caused by partial management only considering the groundwater quantity and quality would lower the water use efficiency, and then cause unacceptable economic losses for the enterprises and the government. Our research highlights that the interdisciplinary management of groundwater resources based on the S-O model could significantly improve practicability in groundwater policymaking, and provides a typical reference for the other developing regions facing difficulty in groundwater management during coastal urban planning and economic transformation.


Assuntos
Monitoramento Ambiental , Água Subterrânea , Cidades , Água do Mar , Água
2.
Water Res ; 212: 118111, 2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35091218

RESUMO

The quantification of trade-offs between social-economic and environmental effects is of great importance, especially in the semi-arid coastal areas with highly developed agriculture. The study presents an integrated multi-objective simulation-optimization (S-O) framework to evaluate the basin-scale water-environment-agriculture (WEA) nexus. First, the variable-density groundwater model (SEAWAT) is coupled to the reactive transport model (RT3D) for the first attempt to simulate the environmental effects subject to seawater intrusion (SWI) and nitrate pollution (NP). Then, the surrogate assisted multi-objective optimization algorithm is utilized to investigate the trade-offs between the net agricultural benefits and extents of SWI and NP while considering the water supply, food security, and land availability simultaneously. The S-O modeling methodology is applied to the Dagu River Basin (DRB), a typical SWI region with intensive agricultural irrigation in China. It is shown that the three-objective space based on Pareto-optimal front can be achieved by optimizing planting area in the irrigation districts, indicating the optimal evolution of the WEA nexus system. The Pareto-optimal solutions generated by multi-objective S-O model are more realistic and pragmatic, avoiding the decision bias that may often lead to cognitive myopia caused by the low-dimensional objectives. Although the net agricultural benefits in Pareto-optimal solutions are declined to some extent, the environmental objectives (the extents of SWI and NP) are improved compared to those in the pre-optimized scheme. Therefore, the proposed multi-objective S-O framework can be applied to the WEA nexus in the river basin with intensive agriculture development, which is significant to implement the integrated management of water, food, and environment, especially for the semi-arid coastal aquifers.


Assuntos
Água Subterrânea , Nitrogênio , Agricultura , Monitoramento Ambiental , Água , Abastecimento de Água
3.
Sci Total Environ ; 815: 152879, 2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-34995596

RESUMO

Most lakes on the Qinghai-Tibet Plateau have expanded in recent years. Zonag Lake, a critical habitat for Tibetan antelopes in the continuous permafrost zone, burst and overflowed after several years of expansion, resulting in a reduction of approximately 100 km2 in the lake area. Observations have revealed new permafrost is forming on the exposed bottom, accompanied by various periglacial landscapes. The permafrost aggradation on the exposed bottom is rapid, and the permafrost base reached 4.9 m, 5.4 m, and 5.7 m in the first three years, respectively. In this study, the future changes and influencing factors of recently formed permafrost are simulated using a one-dimensional finite element model of heat flow. The simulated results indicate that the permafrost on the exposed bottom is likely to continue to develop, appearing first quick back slow trend. Besides the surface temperature, the annual amplitude is also an important factor in affecting the aggradation of permafrost. The unidirectional permafrost aggradation in the study area is different from the bidirectional permafrost aggradation on the closed taliks around the Arctic. Additionally, snow cover and vegetation are two important factors influencing the future development of permafrost on the exposed lake bottom.


Assuntos
Pergelissolo , Regiões Árticas , Ecossistema , Lagos , Tibet
4.
Environ Sci Pollut Res Int ; 29(17): 24672-24681, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34826077

RESUMO

The widespread usage of per- and polyfluoroalkyl substances (PFASs) has led to their ubiquitous co-existence with hydrocarbon surfactants in the subsurface environment. In this study, column experiments were conducted to investigate the effect of an anionic hydrocarbon surfactant (sodium dodecylbenzene sulfonate, SDBS, 1 and 10 mg/L) on the transport of perfluorooctanoic acid (PFOA) in two saturated natural soils under different cation type (Na+ and Ca2+) conditions. Results showed that SDBS (10 mg/L) significantly enhanced the transport of PFOA in two soils. This was likely because SDBS had a stronger adsorption affinity to the soils than PFOA, and can outcompete PFOA for the finite adsorption sites on the soil surface. The effect of SDBS on PFOA transport varied greatly in the two soils. More negatively charged soil surface and greater soil particle size likely contributed to the more noticeable transport-enhancement of PFOA resulting from the presence of SDBS. Also, the enhancement effect of SDBS (10 mg/L) with Ca2+ on PFOA transport was more significantly than that with Na+. This was possibly due to the blocking effect of SDBS to the more positively charged soil surface induced by Ca2+. Findings of this study point out the importance of anionic hydrocarbon surfactants on PFOA transport when assessing its environmental risks and implementing remediation efforts.


Assuntos
Fluorcarbonetos , Poluentes do Solo , Caprilatos , Solo , Poluentes do Solo/análise , Tensoativos
5.
Sci Total Environ ; 804: 149822, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34517329

RESUMO

Rising CO2 levels will change the behavior and toxicity of soil contaminants. However, it remains unclear whether elevated CO2 levels will change the nanoparticle dissolution or their biological effects in soil. In this study, we used a free-air CO2 enrichment system to examine the effects of elevated CO2 on phytotoxicity and bacterial toxicity of zinc oxide nanoparticles (nZnO) in a paddy soil system. The elevated CO2 changed the nZnO diffraction in soil, slightly increasing its dissolution but remarkably improving its bioavailability. Elevated CO2 did not change Zn accumulation in rice, but still alleviated the adverse effects of nZnO on rice growth, although grain protein, K and P decreased. Moreover, nZnO alone significantly decreased the number of observed soil bacterial species and altered the community organization, while elevated CO2 moderated such changes. Overall, these results increase our understanding of plant response and microbial variation in nanoparticle-contaminated soil under elevated-CO2 conditions. It is necessary to pay attention to soil pollution while facing climate change.


Assuntos
Nanopartículas , Oryza , Óxido de Zinco , Bactérias , Dióxido de Carbono/análise , Dióxido de Carbono/toxicidade , Nanopartículas/toxicidade , Solo , Óxido de Zinco/toxicidade
6.
Ecotoxicol Environ Saf ; 228: 113005, 2021 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-34839141

RESUMO

Column experiments were conducted to investigate the effects of ion type, ion strength, humic acid (HA), and nanometer alumina (NA) particles on the transport of hexavalent chromium (HC) in saturated porous media. A one-dimensional model is developed to simulate the migration of HC affected by NA particles. The results show that nano-alumina particles would enhance the mobility of HC in saturated porous media. However, the influence of NA on the migration of HC in porous media is complex. When the concentration of NA reaches 30 mg/L, HC has minimum retention parameter and best mobility. The transport of HC also is affected by ion strength and ion type. Higher ionic strength would decrease the retention of HC and enhance its mobility. Compared with sodium ion, calcium ion has larger effects on the transport of HC. Moreover, HA can improve the mobility of HC in saturated porous media, but the corresponding promoting effect decreases with the increase of HA concentration. As nanometer contaminants and HC come into the subsurface environment, findings from this study elucidate the key factors and processes controlling the transport of HC in porous media, which can promote the prediction and assessment of HC in the groundwater system.

7.
Phys Rev E ; 103(5-1): 053309, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-34134274

RESUMO

The lattice-Boltzmann method is convenient for simulating flow fields in porous media. However, due to its lattice characteristics, the velocity near a solid surface is not accurate, which results in significant errors when simulating colloid transport in porous media. Based on the general properties of a flow field close to a solid surface, we propose an alternative velocity interpolation method in which the velocity at a solid surface is strictly zero. Numerical simulation results show that the proposed method can give more accurate results than the usual bilinear interpolation. In addition, we use this method to simulate the contact efficiency of colloids in porous media and obtain a new power-law form of the contact efficiency.

8.
J Hazard Mater ; 413: 125362, 2021 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-33930947

RESUMO

Root exudates are a major source of dissolved organic matters that strongly affect the stability and transport behaviors of nanomaterials in porous media. This study investigated the effect of citric acid (CA) and oxalic acid (OA), two common low molecular weight root exudates, on the stability and transport of graphene oxide (GO) in saturated sand columns under different combinations of pH (4.5, 7.0), ionic strength (IS: 10, 50 mM), and organic acid concentrations (10, 25 mM). Both OA and CA accelerated GO aggregation, especially under high IS and acid concentration conditions. With the presence of OA/CA (≥ 10 mM), the transport of GO was higher at pH of 7.0 than 4.5, and the GO mobility decreased with increasing IS and OA/CA concentrations, whereas, enhanced GO transport was observed at a low concentration of OA/CA (0.1 mM), indicating that the influence of organic acid was concentration-dependent. All the results suggest that perturbations of surface potential of GO and sand, as well as the chemical structure of organic acids under different solution chemistry conditions are crucial in controlling GO stability and transport behaviors. Mathematical models based on the advection-dispersion equation with one-site kinetics simulated the experimental breakthrough curves of GO very well.

9.
J Contam Hydrol ; 241: 103809, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33866142

RESUMO

High-resolution characterization of complex dense non-aqueous phase liquid (DNAPL) contaminated sites is crucial for developing effective remediation strategies. The DNAPL source zone is usually characterized by hydraulic/partitioning tracer tomography (HPTT). However, the HPTT method may fail to capture the highly saturated pool-dominated DNAPL source zone architecture (SZA), because partitioning tracers tend to bypass the low-permeability zones where the pool DNAPL accumulates, resulting in a low-resolution DNAPL estimation. With a limited number of measurements, the estimation errors may be significant. To overcome these difficulties, time-lapse electrical resistivity tomography (ERT) was integrated with the partitioning interwell tracer test (PITT) and hydraulic tomography (HT) to characterize the pool-dominated DNAPL SZA. Herein, we proposed an iterative joint inversion framework coupling the multiphase flow model with the ERT forward model to estimate the heterogeneous permeability distribution and DNAPL SZA. Under this framework, permeability was estimated using the hydraulic head data from HT in stage 1, and the DNAPL SZA was subsequently estimated by assimilating both the PITT and ERT observations in stage 2. The permeability estimated from stage 1 was used as prior information for stage 2, and the DNAPL saturation estimated from stage 2 was served as prior information for stage 1 in the next loop to form an iterative loop to improve the estimation of both permeability and DNAPL SZA. The iterative joint inversion framework was evaluated in two numerical experiments with different heterogeneous structures by assimilating multi-source datasets, including hydraulic head, partitioning interwell tracer concentration, and electrical resistivity. Results show that with limited measurements of HPTT method, one can roughly capture the DNAPL distribution, missing the fine structure of the DNAPL SZA. In contrast, by incorporating multi-source datasets, the heterogeneous permeability and DNAPL SZA can be reconstructed with a higher resolution. Furthermore, the inversion accuracy of the DNAPL SZA improves progressively as the iteration proceeds, which demonstrates the advantage of utilizing complementary information from permeability and DNAPL distribution through the iteration framework. Comparing with the results without loop iteration, the estimation error is reduced by 17.3% for permeability and 8.6% for DNAPL saturation in Experiment 1; by 14.7% for permeability and 11.2% for DNAPL saturation in Experiment 2 through the iterative framework. To further evaluate our framework, we preformed the prediction of the depletion process of the DNAPL source zone and plume based on the estimated DNAPL SZA. Results show that using the iterative framework, the prediction of the SZA depletion is greatly improved, i.e., the estimation error of the dissolved downstream plume from the DNAPL source zone after 3 years is reduced by 20.9% in Experiment 1, and by 43.2% in Experiment 2, respectively, through the iterative framework. This significant improvement is because the iterative method can better capture the spread of DNAPL pool.


Assuntos
Poluentes Químicos da Água , Eletricidade , Tomografia , Poluentes Químicos da Água/análise
10.
J Environ Manage ; 282: 111964, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33485034

RESUMO

Coastal aquifer management (CAM) considering conjunctive optimization of pumping and injection system for seawater intrusion (SI) mitigation poses significant decision-making challenges. CAM needs to pose multiple objectives and massive decision variables to explore tradeoff strategies between the conflicting resources, economic, and environmental requirements. Here, we investigate a joint artificial injection scheme for ameliorating SI by establishing an evolutionary multi-objective decision-making framework that combines simulation-optimization (S-O) modelling with a cost-benefit analysis, and demonstrate the framework on a large-scale CAM case in Baldwin County, Alabama. First, a SI numerical model, using SEAWAT, was configured to predict the vulnerable region as an SI encroachment area with the scenarios of minimum and maximum pumping capacity. As a result, a smaller number of candidate sites were selected in the SI encroachment area for implementing groundwater injection to avoid the computationally infeasible SI optimization with an inordinate number of injection related decision variables. Second, the effective S-O methodology of niched Pareto tabu search combined with a genetic algorithm (NPTSGA), which considers the moving-well option, was applied to discover optimal pumping/injection (P/I) strategies (including P/I rates and injection well locations) between three conflicting management objectives under complicated SI constraints. Third, for practical operation of the P/I schemes, a cost-benefit analysis provides judgment criteria to allow decision-makers to implement more sustainable P/I strategies to capture the different realistic preferences. The implementation of three extreme optimization solutions for the case study indicates that, compared to the initial unoptimized scheme, a maximum increase of a factor of 3 in groundwater extraction rates, a maximum reduction of 17% in extent of SI, and a maximum 82.3 million US dollars in comprehensive benefits are specifically achieved by conjunctive P/I optimization. The robustness in the decision alternatives attributed to the uncertainty in physical parameters of hydraulic conductivity was discovered through global sensitivity analysis. The proposed framework provides a decision support system for multi-objective CAM with combined pumping control and engineering measures for SI mitigation.


Assuntos
Água Subterrânea , Análise Custo-Benefício , Objetivos , Água do Mar , Incerteza
11.
Int J Neurosci ; 131(7): 641-649, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32677581

RESUMO

INTRODUCTION: Neuroinflammation and oxidative stress are major mechanisms of post-stroke cognitive impairment (PSCI) neural injury and decreased spatial and memory capacity. Enriched environment (EE) is an effective method to improve cognitive dysfunction. However, the regulation by EE of neuroinflammation, oxidative stress and associated mechanisms in animal models remains unclear. MATERIALS AND METHODS: In this study, a rat PSCI model was established by middle cerebral artery occlusion (MCAO). Rats were randomly divided into the control group, standard environment (SE) group and EE group for 28 days. A Morris water-maze test was used to measure cognitive function at 7, 14 and 28 days after MCAO. Rats were sacrificed on the 28th day. Quantitative PCR, immunohistochemistry and ELISA were respectively used to detect mRNA expression of NF-E2-related factor 2 (Nrf2) and Nrf2 response genes, the expression of IL-1ß and levels of proinflammatory cytokines in the hippocampus. RESULTS: EE improved mNSS scores and cognitive ability in PSCI rats. EE increased mRNA expression of the Nrf2 and Nrf2 response genes, including heme oxygenase-1 (HO-1) and NAD(P)H:quinone oxidoreductase 1 (NQO1). EE significantly decreased the level of malondialdehyde (MDA) and increased the levels of superoxide dismutase (SOD) and glutathione (GSH), in the hippocampus of PSCI rats. EE reduced the number of IL-1ß positive cells in the hippocampus, and IL-1ß levels in the hippocampus and serum. EE increased GFAP-positive astrocytes in the hippocampus, and BDNF levels in the hippocampus and serum. CONCLUSIONS: EE can improve cognitive function in PSCI rats by inhibiting neuroinflammation and oxidative stress.


Assuntos
Elementos de Resposta Antioxidante/fisiologia , Disfunção Cognitiva , Meio Ambiente , AVC Isquêmico , Fator 2 Relacionado a NF-E2/metabolismo , Estresse Oxidativo , Reabilitação do Acidente Vascular Cerebral , Animais , Disfunção Cognitiva/etiologia , Disfunção Cognitiva/metabolismo , Disfunção Cognitiva/terapia , Modelos Animais de Doenças , Infarto da Artéria Cerebral Média/complicações , AVC Isquêmico/complicações , AVC Isquêmico/metabolismo , AVC Isquêmico/terapia , Masculino , /metabolismo , Ratos , Ratos Sprague-Dawley , Transdução de Sinais/fisiologia
12.
J Hazard Mater ; 403: 123688, 2021 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-33264881

RESUMO

Current understanding of perfluorooctanoic acid (PFOA) transport in unsaturated porous media is still limited with significant variability in solution chemistry. Column experiments were conducted to systematically evaluate the impacts of ionic strength (1.5-30 mM) and cation type (Na+ and Ca2+) on PFOA transport in unsaturated quartz sand. The results showed that an increase in ionic strength (1.5-30 mM) led to greater PFOA retardation in unsaturated columns. Meanwhile, Ca2+ caused more PFOA retardation than Na+ at the same unsaturated conditions. These findings were supported by bubble column experiments, which indicated greater PFOA adsorption at the air-water interface with increasing ionic strength or in the presence of Ca2+ in comparison to Na+. Furthermore, the air-water interfacial (AWI) adsorption coefficients calculated from surface tension isotherms also increased with increasing ionic strength or in the presence of Ca2+ in comparison to Na+. These results clearly confirm that higher ionic strength or cation valence significantly promoted PFOA adsorption at the air-water interface, and thus caused greater PFOA retardation during transport in unsaturated porous media. This work points out the importance of considering solution ionic strength and cation type in assessing the transport behavior of PFOA in unsaturated porous media.

13.
Talanta ; 223(Pt 2): 121744, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33298268

RESUMO

Designing fluorescent probe for detecting carboxylesterase 1 is remains challenging. Herein, a red emission human carboxylesterase 1 (CES1) probe (CAE-FP) was synthesized based on fluorescent protein chromophore. Probe CAE-FP can specific detect human CES1 with high selectively. The fluorescence quantum yield was calucated as 0.19. The carboxylic acid ester in CAE-FP could be easily hydrolyzed by CES1 under physiological conditions, and this process could induce the obvious fluorescence signal in red emission region. The detection limit of CES1 was calculated as 84.5 ng/mL. Due to the biological detoxification mechanism of carboxylesterase and the obvious inhibitory effect of pesticides on its activity, CAE-FP was applied to detect carbamate pesticide and have achieved good application results. Since fluorescent protein chromophore has excellent biocompatibility, probe CAE-FP with good cell membrane permeable and was successfully applied to monitor the real activities of CES1 in living cells. In summary, this is one of the few reported fluorescent probes that can specific detect the real-time activity of CES1 in biological samples. Besides, we first applied the fluorescent protein chromophore to construct the specific target enzyme probe. This work would contribute to further investigate CES1-associated physiological and pathological processe.


Assuntos
Carboxilesterase , Praguicidas , Carbamatos , Hidrolases de Éster Carboxílico , Ésteres , Corantes Fluorescentes , Humanos
14.
Bull Environ Contam Toxicol ; 105(3): 422-427, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32740746

RESUMO

This study explored the adsorption of representative non-steroidal anti-inflammatory drugs (NSAIDs), acetaminophen (AP), ibuprofen (IB), and salicylic acid (SA) by biochars. The sorption kinetics were fitted with six commonly used kinetic models, and the isotherm data was well described by both Langmuir and Freundlich models. Biochars of longer pyrolysis time showed better performance with the Langmuir maximum sorption capacities for AP, IB, and SA of 196 mg/g, 132 mg/g, and 48.8 mg/g, respectively. Variation in temperature hardly affected the adsorption performances, while the influence of pH exhibited pronounced dependency on physicochemical properties of both NSAIDs and biochars. Eighteen ball-milled (BM) biochars were then produced under different ball-milling conditions and examined for NSAIDs removal. Compared with unmilled biochars, BM-biochars produced under optimum conditions showed higher removal efficiencies. Electrostatic interaction and pore width of biochars greatly affected the NSAIDs adsorption onto biochars.


Assuntos
Anti-Inflamatórios não Esteroides/química , Carvão Vegetal/química , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Pirólise , Temperatura
15.
Environ Pollut ; 266(Pt 1): 115343, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32814265

RESUMO

Understanding the subsurface transport of perfluorooctanoic acid (PFOA) is of considerable interest for evaluating its potential risks to humans and ecosystems. In this study, packed-column experiments were conducted to examine the influence of surface roughness on PFOA transport in unsaturated glass beads, quartz sand and limestone porous media. Results showed decreasing moisture content significantly increased the air-water interfacial adsorption of PFOA and led to greater retardation in all three types of porous media. Particularly, rougher surface (limestone > quartz sand > glass beads) and smaller grain size (i.e. a larger solid specific surface area, SSSA) significantly enhanced PFOA retardation under unsaturated conditions. These results were further supported by bubble column experiments and SSSA analysis of porous media, which demonstrate that except for the factors affecting PFOA transport in solid-water interface (e.g. surface charge and chemical heterogeneity), the greater retardation of PFOA during transport is attributed to the larger air-water interfacial areas associated with rougher surface and smaller grain size and hence greater interfacial adsorption of PFOA. Our results indicated the importance of surface roughness on the retention and transport of PFOA in the unsaturated zone.


Assuntos
Ecossistema , Dióxido de Silício , Caprilatos , Fluorcarbonetos , Porosidade
16.
Sci Total Environ ; 737: 139729, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32526571

RESUMO

Water temperature is a controlling indicator of river habitat since many physical, chemical and biological processes in rivers are temperature dependent. Highly precise and reliable predictions of water temperature are important for river ecological management. In this study, a hybrid model named BP_PSO3, based on the BPNN (back propagation neural network) optimized by the PSO (particle swarm optimization) algorithm, is proposed for water temperature prediction using air temperature (Ta), discharge (Q) and day of year (DOY) as input variables. The performance of the BP_PSO3 model was compared with that of the BP_PSO1 (with Ta as the input) and BP_PSO2 (with Ta and Q as the inputs) models to evaluate the importance of the inputs. In addition, a comparison among the BPNN, RBFNN (radial basis function neural network), WNN (wavelet neural network), GRNN (general regression neural network), ELMNN (Elman neural network), and BP_PSO-based models was carried out based on the MAE, RMSE, NSE and R2. The eight artificial intelligence models were examined to predict the water temperature at the Cuntan and Datong stations in the Yangtze River. The results indicated that the hybrid BPNN-PSO3 model had a stronger ability to forecast water temperature under both normal and extreme drought conditions. Optimization by the PSO algorithm and the inclusion of Q and DOY could help capture river thermal dynamics more accurately. The findings of this study could provide scientific references for river water temperature forecasting and river ecosystem protection.

17.
Environ Res ; 187: 109500, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32460089

RESUMO

Based on the existing comprehensive ecological risk assessment methods of PAHs, this paper proposed an improved hierarchical Archimedean copula integral assessment (HACIA) model with the optimization in the model selection mechanism and accelerating the calculation speed, and according to which performed the sensitivity analysis of the integrated risk relative to the underlying grouped risk probability. Taihu Lake in China and the Bay of Santander in Spain were taken as study areas, whose samples were obtained and extracted concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs). After briefly analyzing their concentration characteristics and source, their comprehensive ecological risks were evaluated by the improve HACIA model and their sensitivity was also analyzed. The results proved that, for Taihu Lake, pyrogenic sources occupied the dominance, especially grass, coal and wood combustion, while the risk proportion of 5-rings PAHs was the lowest indeed based on the improved HAICA model. For the Bay of Santander, source apportionment indicated both petrogenic and pyrogenic sources, mainly from vehicle emissions including gasoline and diesel engines, and 4-ring PAHs were urgently needed to be managed. However, the sensitivity analysis results of two study areas showed that the most effective control target for reducing integral risk has no obvious relationship with the maximum grouped risk. And a clear linear relationship between the maximum sensitivity range and the logarithm of the initial overall risk only presented in one of study areas, which required further research to clarify. In brief, the improved HACIA model is helpful to evaluate the comprehensive ecological risk of 16 PAHs, and formulate risk management strategies based on grouped risk assessment and sensitivity analysis, with the former points out the admonitory risk and the latter helps to find the most effective mitigation measures.


Assuntos
Hidrocarbonetos Policíclicos Aromáticos , China , Monitoramento Ambiental , Hidrocarbonetos Policíclicos Aromáticos/análise , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , Medição de Risco , Espanha
18.
Sci Total Environ ; 724: 138257, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32247119

RESUMO

A mechanistic understanding of perfluorooctanoic acid (PFOA) toxicity to plants is essential for future risk assessment of PFOA in agricultural soil. In this study, soil-grown cucumber (Cucumis sativus) was exposed to 0, 0.2, and 5 mg/kg of PFOA for 60 days. At harvest, contaminant accumulation, cucumber biomass, photosynthesis profiles and metabolites were measured. Results showed that PFOA depressed cucumber biomass and accumulated highest in leaves. Photosynthesis analysis revealed that PFOA at both doses reduced the chlorophyll contents and net photosynthesis rate of cucumber leaves. Gas chromatography-mass spectrometry-based non-targeted metabolomics revealed that PFOA induced metabolic reprogramming in cucumber leaves, including up-regulation of phenols (at 0.2 and 5 mg/kg) and down-regulation of amino acids (at 5 mg/kg), indicating disrupted nitrogen and carbon metabolism. Results revealed how PFOA represses plant growth by down-regulating photosynthetic pigments and disturbing the metabolism of carbohydroxides, phenols and amino acids. These findings provide valuable information for understanding the molecular mechanisms involved in plant responses to PFOA-induced stress.


Assuntos
Cucumis sativus , Caprilatos , Fluorcarbonetos , Metabolômica , Fotossíntese , Folhas de Planta
19.
Am J Cancer Res ; 10(2): 473-490, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32195021

RESUMO

Recently, the combination of platinum chemotherapy with PD-1/PD-L1 pathway blockades has shown synergistic efficacy in a few clinical trials. However, the exact mechanisms and the optimized sequence of such combinations are not fully clear. In this study, we combined different doses of platinum agents (cisplatin or oxaliplatin) with sequential therapy of PD-1 blockade therapy (anti-PD-1 antibody or anti-PD-L1 antibody) to treat established MC38 murine colon tumors. Although 10 mg/kg platinum (cisplatin or oxaliplatin) showed no significant effect on tumor growth, its combination with sequential anti-PD-1 antibody administration caused complete tumor remission in 80-100% mice. The synergic therapeutic efficacy was found to be associated with more effector and less exhausted CD8 T cell infiltration in the tumor sites. Platinum chemotherapy is generally considered immunosuppressive, with lymphopenia and neutropenia being common side effects. However, our data showed that high-dose (20 mg/kg) platinum treatment induced lymphopenia in MC38 tumor-bearing mice, and low-dose (10 mg/kg) treatment augmented the T cell response with an increased number of peripheral T cells. Notably, increased numbers of PD-1 positive CD8 T cells were found in draining lymph nodes, peripheral blood and tumor tissues three days after 10 mg/kg oxaliplatin treatment, and increased numbers of CD8 T cells and apoptotic tumor cells were detected at the edge of tumor tissues. Further investigation showed that the death of tumor cells induced by platinum compounds promoted T cell activation. Moreover, increased expression of T cell-attracting chemokines (CXCL9, CXCL10 and CCL5) was detected in MC38 cells after platinum treatment. These data indicated that the optimal dose of platinum chemotherapy could trigger T cell activation and recruitment into tumors, and sequential PD-1 blockade could prevent newly arriving T cell from becoming exhausted in tumor sites. These findings highlight the importance of optimizing the dose and timing of platinum chemotherapy combined with PD-1 blockade and provide an indication for the improvement of combined therapies in clinical trials.

20.
Water Res ; 175: 115685, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32172055

RESUMO

Understanding subsurface transport of per- and polyfluoroalkyl substances (PFASs) is of critical importance for the benign use and risk management of PFASs. As one of the most commonly found PFASs, perfluorooctanoic acid (PFOA) is used as a representative PFAS and water-saturated column experiments were conducted to investigate the effect of Al/Fe oxyhydroxide coating and ionic strength on its transport at an environmentally relevant PFOA concentration (6.8 µg L-1). Our results showed a clear increase in PFOA retardation in Al/Fe oxyhydroxide coated sand (retardation factor: Al: 1.87-5.58, Fe: 1.28-4.05) than those in uncoated sand (1.00-1.05), due to the stronger electrostatic attraction between anionic PFOA and Al/Fe oxyhydroxide coated sand surface. Notably, Al oxyhydroxide have a more profound effect on PFOA retention and retardation than Fe oxyhydroxide. Besides, higher ionic strength significantly inhabited PFOA retention and retardation in positively charged sand, and the considerable retention of PFOA (∼90%) in deionized water than those in 1.5 mM and 30.0 mM NaCl (<10%) clearly proves the role of competitive adsorption of Cl- on PFOA transport in positively charged sand. In contrast, higher ionic strength (0 mM-30 mM NaCl) slightly increased PFOA retardation in negatively charged sand, illustrating the dominance of electrostatic interaction. Our findings advance current knowledge to understand PFOA transport in natural media with different surface charge property under environmental PFOA concentrations.


Assuntos
Fluorcarbonetos , Caprilatos , Concentração Osmolar , Porosidade , Dióxido de Silício
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...