A much improved understanding of how farmyard manure application may affect carbonate rock dissolution is needed in order to predict possible feedbacks between the rock carbon cycle and the global climate system. Two ...A much improved understanding of how farmyard manure application may affect carbonate rock dissolution is needed in order to predict possible feedbacks between the rock carbon cycle and the global climate system. Two carbonate mineral rock tablets; dolomite and limestone were buried at six depths between 0 and 110 cm in a soil typical of the subtropical karst area in Guiyang City, Guizhou Province. The extent of tablet dissolution, soil CO2, soil p H, soil water content, soil mineral and chemical composition, and chemical composition of soil water were tested in order to assess the degree of dissolution under manure application over the course of one year. The results show that manure addition decreases the dissolution rate of carbonate rocks; limestone and dolomite by between 11.7%-116.9% and 25.0%-65.69% respectively, with the dissolution rate of limestone consistently exceeding that of dolomite under the same conditions. Our data indicates that the rate of pedogenesis of the dolomite and limestone rocks is decreased as much as 35.77% and 59.41% respectively, as a result of manure application. Moreover, the results suggest that manure application accelerated the generation of soil CO2, with soil CO2 concentration increasing on average by 93.94%, and the CO2 flux increasing by 67.64% compared with the control profile. Finally, the data also indicates that manure decreases CO2 uptake by dissolution of carbonate rocks by 25.50%-39.45% on a Guiyang city scale. The counteraction of the CO2 sink contributed by karst water due to farmyard manure utilization in general karst area（both dolomite and limestone） however was 59.41%-62.72%, indicating the application of manure successfully reduces both dissolution and CO2 release to the atmosphere.展开更多
Coagulation followed by sedimentation, as a conventional technique in the water treatment plant, can be the first line of defense against exposures of carbon nanotubes （CNTs） to aquatic organisms and human beings, w...Coagulation followed by sedimentation, as a conventional technique in the water treatment plant, can be the first line of defense against exposures of carbon nanotubes （CNTs） to aquatic organisms and human beings, which has been rarely documented. This study investigated the removal of dispersant-stabilized CNT suspensions by poly aluminum chloride （PAC1） and KAl（SO4）2-12H20 （alum）, with a focus on the effects of dispersant type, coagulant type and dosage. PAC1 performed better than alum in the removal of tannic acid-, humic acid-, and sodium dodecyl benzenesulfonate-stabilized CNTs, but worse for polyethylene glycol octylphenyl ether （TX100）-stabilized CNTs. Neither coagulant could effectively precipitate cetyltrimethyl ammonium bromide-stabilized CNTs. The removal by PACl first increased up to a plateau and then decreased with the continued increase of coagulant dosage. However, the removal rates leveled off but did not decrease after achieving their highest level with the continued addition of alum. The coagulation and flocculation of the CNT suspensions by PACl could be regulated mainly by the mechanism of adsorption charge neutralization, whereas the coagulation by alum mainly involved electrical double-layer compression.展开更多
文摘A much improved understanding of how farmyard manure application may affect carbonate rock dissolution is needed in order to predict possible feedbacks between the rock carbon cycle and the global climate system. Two carbonate mineral rock tablets; dolomite and limestone were buried at six depths between 0 and 110 cm in a soil typical of the subtropical karst area in Guiyang City, Guizhou Province. The extent of tablet dissolution, soil CO2, soil p H, soil water content, soil mineral and chemical composition, and chemical composition of soil water were tested in order to assess the degree of dissolution under manure application over the course of one year. The results show that manure addition decreases the dissolution rate of carbonate rocks; limestone and dolomite by between 11.7%-116.9% and 25.0%-65.69% respectively, with the dissolution rate of limestone consistently exceeding that of dolomite under the same conditions. Our data indicates that the rate of pedogenesis of the dolomite and limestone rocks is decreased as much as 35.77% and 59.41% respectively, as a result of manure application. Moreover, the results suggest that manure application accelerated the generation of soil CO2, with soil CO2 concentration increasing on average by 93.94%, and the CO2 flux increasing by 67.64% compared with the control profile. Finally, the data also indicates that manure decreases CO2 uptake by dissolution of carbonate rocks by 25.50%-39.45% on a Guiyang city scale. The counteraction of the CO2 sink contributed by karst water due to farmyard manure utilization in general karst area（both dolomite and limestone） however was 59.41%-62.72%, indicating the application of manure successfully reduces both dissolution and CO2 release to the atmosphere.
基金supported by the National Basic Research Program (973) of China (No. 2008CB418204)the National Natural Science Foundation of China (No. 21077089,40873072)+1 种基金the Zhejiang Provincial "Qianjiang Talent Program" (No. 2010R10041)Zhejiang Provincial Innovative Research Team of Water Treatment Functional Materials and their Application
文摘Coagulation followed by sedimentation, as a conventional technique in the water treatment plant, can be the first line of defense against exposures of carbon nanotubes （CNTs） to aquatic organisms and human beings, which has been rarely documented. This study investigated the removal of dispersant-stabilized CNT suspensions by poly aluminum chloride （PAC1） and KAl（SO4）2-12H20 （alum）, with a focus on the effects of dispersant type, coagulant type and dosage. PAC1 performed better than alum in the removal of tannic acid-, humic acid-, and sodium dodecyl benzenesulfonate-stabilized CNTs, but worse for polyethylene glycol octylphenyl ether （TX100）-stabilized CNTs. Neither coagulant could effectively precipitate cetyltrimethyl ammonium bromide-stabilized CNTs. The removal by PACl first increased up to a plateau and then decreased with the continued increase of coagulant dosage. However, the removal rates leveled off but did not decrease after achieving their highest level with the continued addition of alum. The coagulation and flocculation of the CNT suspensions by PACl could be regulated mainly by the mechanism of adsorption charge neutralization, whereas the coagulation by alum mainly involved electrical double-layer compression.
