[Source Apportionment and Health Risk Assessment of Heavy Metals in Dust Around Bus Stops in Kaifeng City Based on APCS-MLR Model].

In order to reveal the influence of urban transportation systems on the quality of urban ecological environment, this study selected surface dust from bus stops, which is strongly disturbed by transportation, as the research object. The contents of eight heavy metals (V, Cr, Co, Ni, Cu, Zn, Cd, and Pb) in the dust were determined through inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectroscopy (ICP-ASE). The spatial distribution characteristics and pollution levels of the eight heavy metals in the dust were analyzed using the geo-accumulation index method. A combined qualitative (correlation analysis and principal component analysis) and quantitative (absolute principal component scores-multiple linear regression model (APCS-MLR)) method was used to explore the sources of heavy metals in surface dust near bus stops. The spatial distribution characteristics of heavy metals from different sources were elucidated using the Kriging interpolation method. The health risk assessment model proposed by the United States Environmental Protection Agency was used to evaluate the human health risks. The results showed that the average values of ω(V), ω(Cr), ω(Co), ω(Ni), ω(Cu), ω(Zn), ω(Cd), ω(Pb), and ω(As) in the bus stop surface dust were 68.36, 59.73, 5.81, 19.34, 40.10, 208.32, 1.01, and 49.46 mg·kg-1, respectively. The concentrations of heavy metals (Cd, Zn, Pb, Cu, and Cr) in the dust were all higher than the background values in the surrounding dust, exceeding them by 3.37, 2.70, 2.01, 1.95, and 1.28 times, respectively. The order of the geo-accumulation index for the eight heavy metals was Cd > Zn > Pb > Cu > Cr > V > Ni > Co, with Cd, Zn, Cu, and Pb in the dust indicating mild pollution levels and the others showing no pollution. The source analysis results showed that Cr, Co, and Ni were natural sources, whereas Cu, Zn, Pb, and Cd were traffic sources, and V was derived from a combination of industrial and natural sources. The APCS-MLR results indicated that the average contribution rates of the four sources were as follows:natural source (34.17 %), traffic source (29.84 %), industrial-natural mixed source (14.64 %), and unknown source (21.35 %). The spatial distribution map of the contribution rate of the traffic source was consistent with the trends of traffic volume and bus route density distribution. According to the health risk assessment, the cancer risk and non-cancer risk for children were both higher than those for adults. Cr was the main non-cancer factor, and Cd was the main cancer-causing factor. Natural and traffic sources contributed the most to non-cancer risk and cancer risk, respectively.

Origin of Grain-Coating Chlorite and Implications for Reservoir Quality in the Triassic Deep-Buried Volcaniclastic Sandstones, Central Junggar Basin, Northwestern China.

The occurrence and genesis of grain-coating chlorite were investigated in order to evaluate the impact of grain-coating chlorite on preserving porosity in the deep-buried Triassic Karamay volcaniclastic sandstones based on thin sections, scanning electron microscopy, and an electron probe. Grain-coating chlorite was formed during the eogenesis, originating from the precursor of smectite through the solid-state transformation (SST) mechanism. The hydration and dissolution of unstable, intermediately basic volcanic rock fragments provided essential Fe2+ and Mg2+ ions for the formation of grain-coating chlorite. Due to relatively high stability and low susceptibility to dissolution, acidic volcanic rock fragments could not promote chlorite formation but resulted in authigenic quartz and clays as pore-filling cements. This process would destroy reservoir properties. Under high hydraulic conditions, medium- to coarse-grained sandstone experienced saltation transport, creating significant velocity differentials and pressure differentials on grain surfaces. Subsequently, clay grains adhere to the surfaces, forming grain-coating chlorite during diagenesis with good continuity. In contrast, pebbly sandstone undergoes rolling transport, resulting in smaller velocity differentials on grain surfaces. This makes relatively ineffective clay adsorption and leads to discontinuous grain-coating chlorite in subsequent stages. Under weak hydraulic conditions, grains and clay particles in fine-grained sandstone undergo suspended transport, lacking mutual movement and velocity differentials. Clay particles cannot effectively cover particles but instead fill the pores between them. Therefore, continuous grain-coating chlorite is more commonly developed in the medium- to coarse-grained sandstones and is crucial for inhibiting quartz cementation with a coverage rate exceeding 80%. Inadequate coatings fail to inhibit quartz cementation effectively, while excessive coatings may block pore throats. Optimal protection of primary porosity could occur only when grain-coating chlorite is moderately developed.

Influence of copper and aging on freely dissolved tetracycline concentration in soil.

Copper (Cu) and tetracyclines (TCs) often coexist in agricultural soils because of the use of manures on farmland; however, the influence of Cu on the bioavailability of TCs is still unclear, especially for cases with aging Cu. The freely dissolved concentrations (FDCs) of TCs are believed to be directly related to their bioavailability. In the present study, the FDCs of TCs were determined using organic-diffusive gradients in thin films (o-DGT), and the influence of Cu on the FDCs of TCs in soils was evaluated. The results showed that the FDCs of tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC) were 0.11-0.93, 0.28-1.02, and 0.24-0.53 µg/kg in the CK groups (no Cu added) and accounted for 0.09-0.58, 0.10-1.40, and 0.05-1.19‰ of their total concentrations which ranged from 0.2 to 10.0 mg/kg for TC, OTC, and CTC, respectively. The co-contamination of Cu reduced the FDCs of TCs in most cases, and aging increased the influence of Cu. The presence of Cu resulted in a decrease in the TC FDC by 35.48-95.04% in aged soils and 3.42-87.19% in newly prepared soils. FTIR analysis revealed that aging facilitated the bonding of Cu to soil particles via Cu-O, and Cu bonded to groups such as hydroxyl groups (-OH) in TCs. Our results suggested that the presence of Cu might reduce the bioavailability of TCs, and aging would enhance these effects. This is helpful for the bioavailability analysis of TCs under co-contamination of heavy metals.

The Flow Stress Behavior and Physical-Based Constitutive Model for As-Quenched Al-Zn-Mg-Cu Alloy.

Although heat-treatable Al-Zn-Mg-Cu alloys are widely used in aerospace industries, distortion and cracks exist due to the residual stress during quenching. Understanding the flow stress behavior and numerically modeling the process is the key to predicting the residual stress. This paper investigated the flow stress behavior of the as-quenched 7050 alloy at strain rates from 0.1 s-1 to 1 s-1, temperatures between 423 K and 723 K, and cooling rates from 0.1 K/s to 10 K/s. The experimental results showed that the strain rate, cooling rate, and temperature have effects on the flow stress value, except for the cooling rates at a temperature of 423 K or 723 K. The kinetics model was used to obtain the precipitate features, i.e., precipitate size and volume fraction. Then, a physical constitutive model based on the evolution of immobile dislocation, solutes, and precipitates was developed. The predicted flow stresses showed good agreement with the experimental data. The findings of this work expand the knowledge on the as-quenched flow behavior of Al-Zn-Mg-Cu alloys, improving the prediction accuracy of residual stress by FEM.

Hydrocarbon Generation from Low-Mature Saline Lacustrine Sediments Studied Using Machine Learning and Chemometric Methods: The Succession of the Sikeshu Sag, Junggar Basin, NW China.

Significant attention has been given to the extensive development of saline environments in petroliferous basins. Further exploration and studies have discovered that saline environments, such as those for the deposition of source rocks in the Paleogene Anjihaihe (E2-3 a) Formation of the Sikeshu Sag, are ubiquitous in terrestrial lake basins. Previous studies have suggested that the oil reservoirs in the Sikeshu Sag and its peripheral regions are predominantly derived from the black mudstone and coal measures of the Lower Jurassic Badaowan (J1 b) Formation. However, with deeper exploration of the study area, a growing number of reservoirs with geochemical characteristics different from the J1 b oil source have been discovered, indicating that there are oil sources other than the J1 b source rocks. In this study, various machine learning algorithms were used (random forest, RF; convolutional neural networks, CNN; extreme gradient boosting, XGBoost; ElasticNetCV; Bayesian Ridge; and particle swarm optimization-support vector regression) to select the most suitable algorithm for predicting and comparing the quality of potential source rocks. A violin plot and Taylor diagram were applied to visually compare the reliability and application effectiveness of the models. The results demonstrated that XGBoost and RF can become essential tools for predicting the quality of potential source rocks. Moreover, the measured and predicted values of total organic carbon (TOC), hydrocarbon potential (S1 + S2), and hydrogen index indicate that there are three main source rocks: the E2-3 a, Lower Jurassic Sangonghe (J1 s), and J1 b formations. The thermal maturity of the E2-3 a source rocks is still early mature because of the saline-brackish water nature of these rocks, although large-scale hydrocarbon generation and expulsion can be achieved in the early mature stage. Based on their geochemical characteristics and stepwise discriminant analysis, the oils in the Sikeshu Sag and its peripheral regions can be categorized into two types: groups A and B. Comprehensive organic geochemical evidence suggests that genetically, group A oils are originated from E2-3 a less-mature saline lacustrine sedimentary rocks, while group B oils indicate similar affinity to the Jurassic source. Fluid inclusion microthermometry and one-dimensional basin modeling showed that the oil charging periods of group A and B oils were Middle-Late Miocene (13-8 Ma) and Late Oligocene (23-20 Ma), respectively. Quantitative grain fluorescence (QGF) analysis further propose that the hydrocarbon supply region of the E2-3 a sources is mainly located east of the Western Chepaizi Uplift and the interior area of the Sikeshu Sag, which breaks through the previous understanding that the Jurassic coal-derived oil source is the only main contributor in this study area. The research results can be widely applied to assess the petroleum resources of source rocks in similar areas worldwide.

Freezing method assists calcium hypochlorite for synergistically promoting methane production from sludge anaerobic digestion.

Anaerobic digestion is widely considered to be a promising technology for waste activated sludge (WAS) treatment, by which sludge stabilization and resource recovery are simultaneously achieved. The poor reaction efficiency however hinders the large-scale applications of WAS anaerobic digestion technology. This study reported an efficient sludge pretreatment method by combining freezing with calcium hypochlorite (Ca(ClO)2) for enhancing the anaerobic digestion efficiency. Experimental data showed that the optimal combination was freezing at -20 °C coupled with 0.075 g/g VSS (volatile suspended solids) Ca(ClO)2, by which the maximum biomethane production of 274.4 ± 8.2 mL/g VSS was realized, 1.62 times higher than that of the control. Model-based analysis demonstrated that higher potential and rate for methane production were attained by the combined pretreatment. Mechanism analysis revealed that the extracellular polymeric substances (EPS) and microbial cells were both effectively destructed when treated by combined freezing and Ca(ClO)2, and more dissolved organics were generated in consequence. Microbial analysis demonstrated that the co-treated reactor enriched more functional microbes (such as Methanosaeta, Methanosarcina and Candidatus_Methanofastidiosum) responsible for biomethane generation than that of the control. Furthermore, the number of fecal coliform was largely reduced in co-treated reactor. As the correlation between sludge anaerobic digestion performance and numerous pretreatment parameters was systematically revealed, this study can provide important references for engineers when applying the combined freezing and Ca(ClO)2 technology in practical engineering.

Development of organic-diffusive gradients in thin films technique for measuring freely dissolved concentrations of tetracyclines using a commercial SPE packing.

The freely dissolved concentrations (FDCs) of pollutants are related to their bioavailability in the environment, and the diffusive gradients in thin films technique (DGT) can obtain the FDC of an analyte. Aiming for the detection of the FDCs of tetracyclines (TCs), we used a polyacrylamide hydrogel comprising acrylamide and acrylaide agarose cross-linker as diffusive and binding gels, and a commercial solid-phase extraction (SPE) packing, namely polymer sorbent (PLS), as an adsorption material in the binding gel for the preparation of the organic-diffusive gradients in thin films (o-DGT) devices. The results showed that the diffusion coefficients of tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC) in the diffusive gels were 1.08 × 10-6, 1.08 × 10-6 and 1.03 × 10-6 cm2/ s at 25 °C, respectively. The binding gel showed excellent performance with adsorption capacities of 534.88-569.42 µg/disc for TC, 527.18-565.98 µg/disc for OTC and 1320.12-1320.86 µg/disc for CTC, respectively. The uptake efficiencies were 94.21-111.12, 71.25-88.44 and 76.10-86.62% for TC, OTC and CTC, respectively, with the TCs concentration of 0.05-10 mg/L. The adsorption kinetics of TCs could be described with a pseudo-second-order model (POSM, R2 >0.97). According to the result of adsorption kinetics, the adsorption rate of TCs in the binding gel was not as fast as that of heavy metals, suggesting that the TCs concentrations at the boundary of binding gels in the o-DGT devices could not decrease to zero. After correction of the boundary concentration, the FDCs accounted for 30.30-56.90, 48.10-64.68 and 16.55-50.16% for TC, OTC and CTC, respectively, while their concentrations ranged from 0.2 to 10.0 mg/L. Our results suggested that SPE packing might be an ideal adsorption material for o-DGT binding gels, and that adsorption kinetics should be corrected when calculating the FDCs of organic pollutants.

Phytoremediation of cadmium contaminated alkaline soil using the ornamental hyperaccumulator Mirabilis jalapa L. enhanced by double harvesting: a field study.

Ornamental hyperaccumulators are considered ideal plants for phytoremediation of cadmium (Cd)-contaminated soils because of their high accumulation capacity and minimal potential to enter the food chain. Aiming to estimate the phytoremediation efficiency and explore the influence of double harvesting, a filed study was carried out in Cd-contaminated alkaline soil using the ornamental hyperaccumulator Mirabilis jalapa L. Seeds of M. jalapa were sawn with spacing in rows of 15 cm and in lines of 20 cm on April 20th. Three treatments with different harvesting strategies were arranged: all plants were harvested once on September 10th (marked with H0), and the plants were harvested on July 20th for the first time at a height above ground of 50 cm and 30 cm (marked with H1 and H2, respectively), and then, they were harvested on September 10th for the second time. The plant samples were digested with a mixture of HNO3 and HClO4 and determined using ICP-MS. The results showed that the total biomass of the shoots increased from 505.81 ± 8.29 g/m2 in the H0 treatment to 849.72 ± 59.73 and 933.14 ± 96.12 g/m2 in the H1 and H2 treatments, respectively, while the total Cd accumulation in the shoots was 42.32 ± 4.44, 52.99 ± 7.32, and 56.30 ± 6.95 g/ha in the H0, H1, and H2 treatments, respectively. Phytoremediation efficiencies increased by at least 20% after the application of double harvesting. However, double harvesting also decreased the translocation and bioconcentration factors with a reduction of 30-55% because the Cd concentration in the shoots was low at the first harvest. Our results suggested that double harvesting is a powerful method to improve phytoremediation efficiency with low costs and minimal risk, and other technologies should be applied together to address the accumulation and translocation of Cd.

Efficiency and kinetics of conventional pollutants and tetracyclines removal in integrated vertical-flow constructed wetlands enhanced by aeration.

The integrated vertical-flow constructed wetland (IVCW) is considered as a potential alternative for domestic wastewater treatment of towns and small cities. Oxygen supply is the main limitation of pollutants removal in IVCWs. In the present study, a field experiment was conducted to evaluate the capacity and kinetics of pollutants removal in IVCWs with/without artificial aeration. Two IVCWs constructed with Canna indica and Phragmites australis were running in continuous flow to remove high concentrations of conventional pollutants and low concentrations of tetracyclines (TETs), which are at similar levels of domestic wastewater. The results showed that IVCWs had a good performance on COD, phosphorus, and TETs with removal efficiencies over 80%, 64%, and 75%, respectively, with a hydraulic retention time (HRT) of 3.0 d. However, the removal of nitrogen was limited, showing as TN removal efficiency of about 30%. The IVCW with Phragmites australis had a higher removal efficiency and rate. A kinetics based on Monod Equation and solved with Matlab 2018a could describe the degradation of conventional pollutants. Artificial aeration improved the oxygen supply and remarkably raised the removal capacity for COD, N, and P in IVCWs. The q1/2 values, which was defined as the average removal loading before half of the pollutants was removed and represented the removal capacity without limitation of pollutants concentration, were increased by 5-30 times after aeration. In conclusion, IVCWs could remove conventional pollutants and TETs simultaneously showing a great potential in domestic wastewater treatment. Artificial aeration enhanced removal capacity of IVCWs on conventional pollutants while showed little influence on TETs.

Phytoremediation of alkaline soils co-contaminated with cadmium and tetracycline antibiotics using the ornamental hyperaccumulators Mirabilis jalapa L. and Tagetes patula L.

The co-contamination of farmland soils with heavy metals and antibiotics from the application of livestock and poultry manures poses great threats to human health. Phytoremediation might be a good solution to this problem. A pot culture experiment was conducted to evaluate the remediation capacity of two ornamental hyperaccumulators, namely, Mirabilis jalapa L. and Tagetes patula L., in alkaline soils co-contaminated with cadmium (Cd) and tetracycline antibiotics (TCs). The growth of M. jalapa and T. patula was significantly influenced by the co-contaminated soil. In treatments with TCs alone, the growth of T. patula was promoted (p < 0.05), while that of M. jalapa was inhibited. In the C2T3 treatment with TCs and Cd combined, the biomass of T. patula and M. jalapa decreased by 42.27% and 56.15% in roots and by 22.24% and 32.27% for in shoots, respectively, compared with those in the same treatment without TCs. The addition of TCs increased the accumulation of Cd in treatments with less than 15.0 mg/kg Cd. In M. jalapa, the concentration of Cd increased by 4.64% and 39.69% in roots and by 30.33% and 71.71% in shoots, and that in T. patula increased by 74.66% and 11.03% in roots and by 15.36% and 17.58% in shoots, respectively, in two treatments with TCs compared with those in the treatments with Cd alone. However, the accumulated Cd amounts decreased from 36.25 to 31.91 µg/pot and increased from 201.33 to 229.26 µg/pot in C2T2 for M. jalapa and T. patula, respectively, compared with those in the treatments without TCs. The TC removal efficiencies of all treatments were above 99%, and the residual amounts of TC and OTC were higher than that of CTC. M. jalapa and T. patula are promising hyperaccumulators that can be used for the remediation of alkaline soil co-contaminated with Cd and TCs.

Establishment and characterization of a novel untransfected corneal endothelial cell line from New Zealand white rabbits.

PURPOSE: To establish and characterize a novel untransfected corneal endothelial cell line from New Zealand white rabbits (NRCE cell line) for studies on corneal endothelial cells. METHODS: Primary culture was initiated with a pure population of NRCE cells from corneal endothelia by successive detachment and reattachment procedure of different durations, and cultured in 20% fetal bovine serum-containing DMEM/F12 media with several supplements. The cell line was characterized by chromosome analysis, fluorescence immunoassay and reverse transcription PCR. The tumorigenic potency of the cell line was examined by subcutaneous inoculation to nude mice. The biocompatibility of the cell line to denuded amnions was examined with routine microscopic and electron microscopic techniques. RESULTS: NRCE cells in primary culture proliferated to confluency in 25 days and has been subcultured to passage 227 to date. The novel NRCE cell line, with a steady growing rate in 20% bovine calf serum (BCS)-containing DMEM/F12 medium and a population doubling time of 40.32 h at passage 191, has been established. NRCE cells exhibited chromosomal aneuploidy but their modal chromosome number was still 44. The results of gene expression patterns of marker proteins and membrane transport proteins, combined with immunofluorescent localization patterns of cell junction proteins, indicated that NRCE cells retained normal corneal endothelial characteristics and normal expression pattern of functional proteins. Furthermore, these cells, without any tumorigenic potency, had excellent biocompatibility to denuded amnions in 20% BCS-containing DMEM/F12 medium, and formed confluent cell sheets attached tightly to denuded amnions. CONCLUSIONS: These results suggest that a novel untransfected NRCE cell line established here maintains normal corneal endothelial characteristics and potencies to form normal cell junctions and perform normal functions of transmembrane transport.

Establishment of a novel corneal endothelial cell line from domestic rabbit, Oryctolagus curiculus.

To develop a rabbit corneal endothelial (RCE) cell line, in vitro culture of RCE cells was initiated from Oryctolagus curiculus corneas and a novel RCE cell line was established in this study. To initiate the primary culture of RCE cells, corneas from rabbit eyes were sliced and attached into glutin-coated wells with endothelial cell surface down. After being cultured at a time-gradient interval from 48 to 6 h, the corneal slices were detached and reattached into new wells, respectively. Cells in the wells containing only a pure population of RCE cells were collected and cultured in 20% FBS-DMEM/F12 medium containing chondroitin sulfate, ocular extract, epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), carboxymethyl-chitosan, N-acetylglucosamine hydrochloride, glucosamine hydrochloride, culture medium of rabbit corneal stromal cells and oxidation-degradation products of chondroitin sulfate at 37 degrees C, 5% CO(2). The cultured RCE cells, in quadrangle and polygonal shapes, proliferated to confluence 3 weeks later. During the subsequent subculture, the shape of RCE cells changed gradually from polygonal to more fibroblastic. A novel RCE cell line, growing at a steady rate, with a population doubling time of 53.8 h, has been established and subcultured to passage 67. Chromosome analysis showed that the RCE cells exhibited chromosomal aneuploidy with the modal chromosome number of 44. The results of immuno-cytochemical staining with neuron specific enolase (NSE) confirmed that the RCE cells were in neuroectodermal origin. Combined with the results of vascular endothelial growth factor (VEGF) treatment and endothelial cell morphology recovery, it can be concluded that the cell line established here is an RCE cell line. This RCE cell line may serve as a useful tool in theoretical researches of mammalian corneal endothelial cells, and may also have potential application in artificial corneal endothelium development.