When adding sufficient chlorine to achieve breakpoint chlorination to source water containing high concentration of ammonia during drinking water treatment, high concentrations of disinfection by-products(DBPs) may ...When adding sufficient chlorine to achieve breakpoint chlorination to source water containing high concentration of ammonia during drinking water treatment, high concentrations of disinfection by-products(DBPs) may form. If N-nitrosamine precursors are present, highly toxic N-nitrosamines, primarily N-nitrosodimethylamine(NDMA), may also form. Removing their precursors before disinfection should be a more effective way to minimize these DBPs formation. In this study, zeolites and activated carbon were examined for ammonia and N-nitrosamine precursor removal when incorporated into drinking water treatment processes.The test results indicate that Mordenite zeolite can remove ammonia and five of seven N-nitrosamine precursors efficiently by single step adsorption test. The practical applicability was evaluated by simulation of typical drinking water treatment processes using six-gang stirring system. The Mordenite zeolite was applied at the steps of lime softening, alum coagulation, and alum coagulation with powdered activated carbon(PAC) sorption. While the lime softening process resulted in poor zeolite performance, alum coagulation did not impact ammonia and N-nitrosamine precursor removal. During alum coagulation, more than67% ammonia and 70%–100% N-nitrosamine precursors were removed by Mordenite zeolite(except 3-(dimethylaminomethyl)indole(DMAI) and 4-dimethylaminoantipyrine(DMAP)). PAC effectively removed DMAI and DMAP when added during alum coagulation. A combination of the zeolite and PAC selected efficiently removed ammonia and all tested seven N-nitrosamine precursors(dimethylamine(DMA), ethylmethylamine(EMA), diethylamine(DEA), dipropylamine(DPA), trimethylamine(TMA), DMAP, and DMAI) during the alum coagulation process.展开更多
High soil salinity imposes osmotic stress and ion toxicity in plants,leading to substantial crop yield loss worldwide.Understanding of the quantitative and dynamic physiological responses to composite soil salt stress...High soil salinity imposes osmotic stress and ion toxicity in plants,leading to substantial crop yield loss worldwide.Understanding of the quantitative and dynamic physiological responses to composite soil salt stress is limited and needs to be expanded.In this study,physiological,nutritional,and biomass yield parameters of tobacco(Nicotiana tabacum L.)grown in soil with five levels of composite soil salinity(CSS),basal CSS level(control,CK)and 3(T_(1)),6(T_(2)),9(T_(3)),and 12(T_(4))times the basal CSS level,under greenhouse were determined at days 30,60,and 90 after transplanting.Leaf dry biomass significantly(P<0.05)increased at the low salinity levels applied(T_(1) and T_(2))at all three time points,whereas it progressively declined as the CSS level further increased.The leaf physiological and photosynthetic responses were more adversely affected by CSS at the early growth stage(day 30).A path coefficient analysis demonstrated that leaf proline content had the largest direct effect(-0.66),and leaf Cu content had the most significant indirect effect(0.49)on leaf dry biomass of plants.The results suggest that lower CSS levels(T_(1) and T_(2))could stimulate tobacco growth(leaf biomass yield,in particular),and higher leaf proline and Cu levels at the early growth stage may potentially increase the ability of tobacco plants to withstand the adverse effects of salinity,which could be considered for future research and development of salinity management strategies.展开更多
基金supported by US EPA STAR program(No.83517301)Missouri Department of Natural Resourcesthe support from Chemistry Department,Environmental Research Center,and Center for Single Nanoparticle,Single Cell,and Single Molecule Monitoring(CS3M)at Missouri University of Science and Technology
文摘When adding sufficient chlorine to achieve breakpoint chlorination to source water containing high concentration of ammonia during drinking water treatment, high concentrations of disinfection by-products(DBPs) may form. If N-nitrosamine precursors are present, highly toxic N-nitrosamines, primarily N-nitrosodimethylamine(NDMA), may also form. Removing their precursors before disinfection should be a more effective way to minimize these DBPs formation. In this study, zeolites and activated carbon were examined for ammonia and N-nitrosamine precursor removal when incorporated into drinking water treatment processes.The test results indicate that Mordenite zeolite can remove ammonia and five of seven N-nitrosamine precursors efficiently by single step adsorption test. The practical applicability was evaluated by simulation of typical drinking water treatment processes using six-gang stirring system. The Mordenite zeolite was applied at the steps of lime softening, alum coagulation, and alum coagulation with powdered activated carbon(PAC) sorption. While the lime softening process resulted in poor zeolite performance, alum coagulation did not impact ammonia and N-nitrosamine precursor removal. During alum coagulation, more than67% ammonia and 70%–100% N-nitrosamine precursors were removed by Mordenite zeolite(except 3-(dimethylaminomethyl)indole(DMAI) and 4-dimethylaminoantipyrine(DMAP)). PAC effectively removed DMAI and DMAP when added during alum coagulation. A combination of the zeolite and PAC selected efficiently removed ammonia and all tested seven N-nitrosamine precursors(dimethylamine(DMA), ethylmethylamine(EMA), diethylamine(DEA), dipropylamine(DPA), trimethylamine(TMA), DMAP, and DMAI) during the alum coagulation process.
基金funded by the Key Laboratory for Tobacco Cultivation of Tobacco Industry of China(No.30800665)the Marine Science and Technology Innovation Fund of Jiangsu Provincial Department of Natural Resources,China(No.JSZRHYKJ202003)+1 种基金the Scientific and Technological Innovation Fund of Jiangsu Provincial Department of Science and Technology,China(No.BE2022304)Luoyang Tobacco Company of China(No.LYKJ201501)。
文摘High soil salinity imposes osmotic stress and ion toxicity in plants,leading to substantial crop yield loss worldwide.Understanding of the quantitative and dynamic physiological responses to composite soil salt stress is limited and needs to be expanded.In this study,physiological,nutritional,and biomass yield parameters of tobacco(Nicotiana tabacum L.)grown in soil with five levels of composite soil salinity(CSS),basal CSS level(control,CK)and 3(T_(1)),6(T_(2)),9(T_(3)),and 12(T_(4))times the basal CSS level,under greenhouse were determined at days 30,60,and 90 after transplanting.Leaf dry biomass significantly(P<0.05)increased at the low salinity levels applied(T_(1) and T_(2))at all three time points,whereas it progressively declined as the CSS level further increased.The leaf physiological and photosynthetic responses were more adversely affected by CSS at the early growth stage(day 30).A path coefficient analysis demonstrated that leaf proline content had the largest direct effect(-0.66),and leaf Cu content had the most significant indirect effect(0.49)on leaf dry biomass of plants.The results suggest that lower CSS levels(T_(1) and T_(2))could stimulate tobacco growth(leaf biomass yield,in particular),and higher leaf proline and Cu levels at the early growth stage may potentially increase the ability of tobacco plants to withstand the adverse effects of salinity,which could be considered for future research and development of salinity management strategies.