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The Routine involving Countryside Ecotourism Stakeholders in Poverty-Stricken Areas of Tiongkok: Ramifications for Outlying Revitalization.
Biodegradation is a significant process for removing organic chemicals from water, soil and sediment environments, and therefore biodegradability is critical to evaluate the environmental persistence of organic chemicals. In this study, based on a dataset with 171 compounds, four quantitative structure-activity relationship (QSAR) models were developed for predicting primary and ultimate biodegradation rate rating with multiple linear regression (MLR) and support vector machine (SVM) algorithms. Two MLR models were built with a dataset with carbon atom number ≤9, and two SVM models were built with a dataset with carbon atom number >9. In the MLR models, nArX (number of X on aromatic ring) is the most important descriptor governing primary and ultimate biodegradation of organic chemicals. For the SVM models, determination coefficient (R2) values, cross-validated coefficients (Q2LOO) and external validation coefficient (Q2ext) values are over 0.9, indicating the SVM models have satisfactory goodness-of-fit, robustness and external predictive abilities. The applicability domains of these models were visualized by the Williams plot. The developed models can be used as effective tools to predict biodegradability of organic chemicals. In this study, the removal performance of a hybrid ozonation-coagulation (HOC) process using AlCl36H2O (Al-HOC) and FeCl36H2O (Fe-HOC) as coagulants for the treatment of wastewater treatment plant (WWTP) effluent and ibuprofen (IBP) was investigated. selleck compound Compared with the conventional coagulation process and pre-ozonation-coagulation process, much better organic matter removal performance can be achieved for both the Al-HOC and Fe-HOC processes. The Fe-HOC process showed an obviously higher dissolved organic carbon (DOC) removal efficiency than that of the Al-HOC process. Surface hydroxyl groups were determined to be the active sites in generating OH in the HOC process, and the hydrolysed Fe species possessed a higher content of surface hydroxyl groups than the hydrolysed Al species according to fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectra (XPS) analyses. In addition, the hydrolysed Fe species contained a higher portion of tetrahedral sites that were more likely to be stronger Lewis acid sites to react with ozone to generate OH. Furthermore, peroxone reactions in the HOC process were other possible way to enhance the OH generation, and higher H2O2 generation was observed in the Fe-HOC process due to higher O2- generation. Therefore, better removal performance of the Fe-HOC process can be obtained due to the increased OH generation in the Fe-HOC process. Soil contamination by pesticide residues is a primary concern because of the high soil persistence of pesticides and their toxicity to humans. We investigated pesticide concentration and distribution at 3 soil depths in 147 soil samples from agricultural land and assessed potential health risks due to non-dietary human exposure to pesticides in Nepal. About sixty percent of the soil samples had pesticides (25% of the soil samples had single residue, 35% of the soil samples had mixtures of 2 or more residues) in 39 different pesticide combinations. Pesticide residues were found more frequently in topsoil. Overall, the concentration of pesticides ranged from 1.0 μg kg-1 to 251 μg kg-1, with a mean of 16 μg kg-1. The concentration of the primary group, organophosphates (OPs), ranged from 1.23 μg kg-1 to 239 μg kg-1, with a mean of 23 μg kg-1. Chlorpyrifos and 3,5,6-trichloro-2-pyridinol (TCP) were the predominant contaminants in soils. The ionic ratio of DDT and its degradation products suggested a continuing use of DDT in the area. Human health risk assessment of the observed pesticides in soil suggested negligible cancer risks and negligible non-cancer risks based on ingestion as the primary route of exposure. The predicted environmental concentrations (PECs) of pesticides were higher than the values found in the guidance for soil contamination used internationally. Low concentrations of residues in the soils from agricultural farms practicing integrated pest management (IPM) suggest that this farming system could reduce soil pollution in Nepal. Prenatal exposure to particulate matter (PM) in ambient air has been linked to changes in newborn mitochondrial DNA copy number (mtDNAcn), but the effects of exposure are inconsistent. We aimed to investigate the effect of weekly PM exposure during pregnancy on newborn mtDNAcn. The present study included 762 mother-infant pairs who were recruited in a birth cohort established between November 2013 and March 2015 in Wuhan, China. Mother's prenatal daily exposure to PM2.5 and PM10 was calculated using a spatial-temporal land use regression model. Relative mtDNAcn in cord blood leukocytes was determined by quantitative real-time polymerase chain reaction. Distributive lag regression models (DLMs) were applied to estimate the association between PM exposure and newborn mtDNAcn. In the adjusted models, prenatal PM2.5 exposure during 25-32 weeks and PM10 exposure during 25-31weeks were significantly associated with decreased cord blood mtDNAcn. PM2.5 exposure during the third trimester was related to decreased mtDNAcn (cumulative percent change -8.55%, 95% CI -13.32%, -3.51%). We also identified other exposure windows (17-22 and 11-22 weeks) in which PM exposure was positively associated with mtDNAcn. Overall, exposure to particulate air pollution during mid-to-late gestation is significantly associated with alterations in newborn mtDNAcn, potentially suggesting an enhanced sensitivity to PM exposure during this period. The iron-air fuel cell (IAFC) has been successfully employed for the oxidative removal of many pollutants, but its feasibility for reductive immobilization of Cr(VI) is still unknown. Herein, we developed an IAFC system consisting of an iron anode and an activated carbon-PTFE based air-cathode, and evaluated its performance for Cr(VI) removal and power generation. In this reaction system, cathodic reduction and Fe(II) reduction both contributed to the reductive removal of Cr(VI). It was found that the decrease of solution pH from 6.0 to 3.0 promoted the removal of Cr(VI) due to the enhanced yield of Fe(II) ions and cathodic reduction, accompanying the increased power generation from 1040 mW m-2 to 2880 mW m-2. Besides, the Cr(VI) removal and power generation could be also promoted by elevating Na2SO4 concentration from 0.01 M to 0.1 M. In the IAFC process, Cr(VI) was initially reduced to less soluble ionic Cr(III) homogeneously and heterogeneously and then Cr(III) was immobilized by adsorption and/or co-precipitation with the fresh Fe(III) (oxy)hydroxides.
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