The construction of a subsurface dam and/or physical cutoff barriers is one of the most known techniques used to prevent seawater intrusion during excessive exploitation of freshwater from a coastal aquifer. This method is widely used in many sites around the world (Japan, Brazil, India, Burkina Faso…). In this study, we present an innovative technique for constructing subsurface barriers based on geochemical reactions. A calcite cutoff wall is developed by mixing two aqueous solutions Na2CO3 and CaCl2 under pCO2 equal to 3.16·10-4 bar. The deposition of calcite in the mixing zone induces a high clogging, which greatly reduces the porosity and then the permeability of the aquifer into the injection zone. We use GEODENS code to study the effect of a developed geochemical cutoff wall on saltwater intrusion and to assess their protective effect on preventing seawater intrusion. The GEODENS code can solve these equations by a finite element procedure; it can handle density-dependent flow, transport, and geochemical reactions in porous media. The effect of depth and location of the geochemical cutoff wall is tested and results showed a significant reduction of seawater intrusion penetration length. According to the budget used in many barrier construction projects, we have shown that the developed geochemical cutoff wall presented in this work could produce a lower seawater intrusion penetration length than the traditionally used barriers at a very lower cost.Manganese activated carbon (Mn-AC) was successfully prepared by the incipient wetness method and characterized by SEM, XRD, and FTIR. This study chose N,N-dimethylformamide (DMF) as the target pollutant, and the removal rate of DMF and removal mechanism were systematically studied by dielectric barrier discharge (DBD) plasma combined with Mn-AC. This study indicated that DBD plasma combined with Mn-AC could effectively remove DMF. With the addition of Mn-AC, the removal rate and mineralization rate of DMF within 40 min increased from 51.5% and 36.0% to 82.2% and 58.2%, respectively. The discharge power, initial concentration of DMF, initial pH of the solution, and dosage of Mn-AC affect the removal of DMF. The optimal discharge power is 16.19 W, and energy efficiency is 20.79 mg·kJ-1; low concentration DMF could be removed more effectively. Neutral and alkaline conditions showed better removal effect of DMF than acid conditions; Mn-AC optimal dosage is 1.0 g L-1. The concentration variations of O3, H2O2, and ·OH manifested that Mn-AC could effectively convert O3 and H2O2 to ·OH, thereby increasing the DMF removal rate. Quenching experiments showed that ·OH is the main active species in the reaction. Based on reaction products of DMF such as N-methylformamide, methanol, formaldehyde, and formic acid, possible degradation pathways were proposed. Prospect analysis demonstrated combining plasma systems with catalysts is promising.Cobalt exposure has adverse health effects on the cardiovascular system in occupational and laboratory studies, but these effects have not been assessed in the general population. We aimed to determine whether serum cobalt levels had relationship with the prevalence of cardiovascular disease (CVD) in the general population. Using data from the National Health and Nutrition Examination Survey (NHANES) (2015-2016), we performed the cross-sectional study. We analyzed the baseline characteristics of 3389 participants (1623 men and 1766 women). Generalized linear models and restricted cubic spline plots curve were undertaken to elucidate the relationship. Stratified subgroup analysis was tested to exclude interaction between different variates and cobalt. Our results showed that the adjusted odds ratios (ORs) with 95% confidence intervals (CIs) for CVD prevalence across the quartiles of cobalt were 0.94 (0.67, 1.30), 1.55 (1.15, 2.10), and 1.74 (1.28, 2.35) compared with lowest quartile. The restricted cubic spline curve also suggested nonlinear and positive association between cobalt and CVD (P for nonlinearity = 0.007). In summary, our cross-sectional results verify that higher cobalt levels are associated with a higher prevalence of cardiovascular disease.The layout of urban spatial functions may play an important role in sustainable regional development. Given the rapid development of urbanization in China, this study attempts to analyze how functional specialization affects coordinated regional development. To quantitatively measure the degree of coordinated development within different regions, the coordinated degree index is used to calculate the degree of coordinated development of four Chinese metropolitan areas from 2008 to 2019. The panel vector autoregressive (PVAR) model is employed to empirically test the impact of urban functional specialization on coordinated regional development. The results indicate that high market activity is conducive to the formation of functional specialization synergy in space, and the level of social productivity directly affects the functional specialization and the level of synergy within a region. With the continuous strengthening of the implementation of local government policies, the functional specialization and synergy in metropolitan areas have gradually strengthened. However, the promotion effects and the expression of functional specialization, the coordinated development of government actions, and spatial functions differ across metropolitan areas in China.Denitrification and NH3 volatilization are the main removal processes of nitrogen in coastal saline soils. In this incubation study, the effects of wheat straw biochar application at rates of 0, 2, 5, 10 and 15% by weight to saline soil with two salt gradients of 0 and 1‰ on denitrification and NH3 volatilization were investigated. https://www.selleckchem.com/products/LBH-589.html The results showed that the denitrification rates with 2, 5 and 10% biochar amendments decreased by 25.26, 33.07 and 17.50%, respectively, under salt-free conditions, and the denitrification rates with 2 and 5% biochar amendments under 1‰ salt conditions decreased by 17.74 and 17.39%, respectively. However, the NH3 volatilization rates increased by 8.05-61.73% after biochar application. The path analysis revealed the interactions of overlying water-sediment system environmental factors in biochar-amended saline soils and their roles in denitrification and NH3 volatilization. Environmental factors in sediment exerted **** greater control over denitrification than those in overlying water.
The construction of a subsurface dam and/or physical cutoff barriers is one of the most known techniques used to prevent seawater intrusion during excessive exploitation of freshwater from a coastal aquifer. This method is widely used in many sites around the world (Japan, Brazil, India, Burkina Faso…). In this study, we present an innovative technique for constructing subsurface barriers based on geochemical reactions. A calcite cutoff wall is developed by mixing two aqueous solutions Na2CO3 and CaCl2 under pCO2 equal to 3.16·10-4 bar. The deposition of calcite in the mixing zone induces a high clogging, which greatly reduces the porosity and then the permeability of the aquifer into the injection zone. We use GEODENS code to study the effect of a developed geochemical cutoff wall on saltwater intrusion and to assess their protective effect on preventing seawater intrusion. The GEODENS code can solve these equations by a finite element procedure; it can handle density-dependent flow, transport, and geochemical reactions in porous media. The effect of depth and location of the geochemical cutoff wall is tested and results showed a significant reduction of seawater intrusion penetration length. According to the budget used in many barrier construction projects, we have shown that the developed geochemical cutoff wall presented in this work could produce a lower seawater intrusion penetration length than the traditionally used barriers at a very lower cost.Manganese activated carbon (Mn-AC) was successfully prepared by the incipient wetness method and characterized by SEM, XRD, and FTIR. This study chose N,N-dimethylformamide (DMF) as the target pollutant, and the removal rate of DMF and removal mechanism were systematically studied by dielectric barrier discharge (DBD) plasma combined with Mn-AC. This study indicated that DBD plasma combined with Mn-AC could effectively remove DMF. With the addition of Mn-AC, the removal rate and mineralization rate of DMF within 40 min increased from 51.5% and 36.0% to 82.2% and 58.2%, respectively. The discharge power, initial concentration of DMF, initial pH of the solution, and dosage of Mn-AC affect the removal of DMF. The optimal discharge power is 16.19 W, and energy efficiency is 20.79 mg·kJ-1; low concentration DMF could be removed more effectively. Neutral and alkaline conditions showed better removal effect of DMF than acid conditions; Mn-AC optimal dosage is 1.0 g L-1. The concentration variations of O3, H2O2, and ·OH manifested that Mn-AC could effectively convert O3 and H2O2 to ·OH, thereby increasing the DMF removal rate. Quenching experiments showed that ·OH is the main active species in the reaction. Based on reaction products of DMF such as N-methylformamide, methanol, formaldehyde, and formic acid, possible degradation pathways were proposed. Prospect analysis demonstrated combining plasma systems with catalysts is promising.Cobalt exposure has adverse health effects on the cardiovascular system in occupational and laboratory studies, but these effects have not been assessed in the general population. We aimed to determine whether serum cobalt levels had relationship with the prevalence of cardiovascular disease (CVD) in the general population. Using data from the National Health and Nutrition Examination Survey (NHANES) (2015-2016), we performed the cross-sectional study. We analyzed the baseline characteristics of 3389 participants (1623 men and 1766 women). Generalized linear models and restricted cubic spline plots curve were undertaken to elucidate the relationship. Stratified subgroup analysis was tested to exclude interaction between different variates and cobalt. Our results showed that the adjusted odds ratios (ORs) with 95% confidence intervals (CIs) for CVD prevalence across the quartiles of cobalt were 0.94 (0.67, 1.30), 1.55 (1.15, 2.10), and 1.74 (1.28, 2.35) compared with lowest quartile. The restricted cubic spline curve also suggested nonlinear and positive association between cobalt and CVD (P for nonlinearity = 0.007). In summary, our cross-sectional results verify that higher cobalt levels are associated with a higher prevalence of cardiovascular disease.The layout of urban spatial functions may play an important role in sustainable regional development. Given the rapid development of urbanization in China, this study attempts to analyze how functional specialization affects coordinated regional development. To quantitatively measure the degree of coordinated development within different regions, the coordinated degree index is used to calculate the degree of coordinated development of four Chinese metropolitan areas from 2008 to 2019. The panel vector autoregressive (PVAR) model is employed to empirically test the impact of urban functional specialization on coordinated regional development. The results indicate that high market activity is conducive to the formation of functional specialization synergy in space, and the level of social productivity directly affects the functional specialization and the level of synergy within a region. With the continuous strengthening of the implementation of local government policies, the functional specialization and synergy in metropolitan areas have gradually strengthened. However, the promotion effects and the expression of functional specialization, the coordinated development of government actions, and spatial functions differ across metropolitan areas in China.Denitrification and NH3 volatilization are the main removal processes of nitrogen in coastal saline soils. In this incubation study, the effects of wheat straw biochar application at rates of 0, 2, 5, 10 and 15% by weight to saline soil with two salt gradients of 0 and 1‰ on denitrification and NH3 volatilization were investigated. https://www.selleckchem.com/products/LBH-589.html The results showed that the denitrification rates with 2, 5 and 10% biochar amendments decreased by 25.26, 33.07 and 17.50%, respectively, under salt-free conditions, and the denitrification rates with 2 and 5% biochar amendments under 1‰ salt conditions decreased by 17.74 and 17.39%, respectively. However, the NH3 volatilization rates increased by 8.05-61.73% after biochar application. The path analysis revealed the interactions of overlying water-sediment system environmental factors in biochar-amended saline soils and their roles in denitrification and NH3 volatilization. Environmental factors in sediment exerted much greater control over denitrification than those in overlying water.
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