摘要
Batch experiments and XAD resin were used to investigate the adsorption of dissolved organic matter(DOM) by ferrallitic soils. The effects of soil properties and DOM characteristics on the adsorption were also studied to reveal the adsorption mechanism. The results showed that:(1) ferrallitic soils were high in DOM adsorption capacity,which increased with initial DOM concentrations,and the kinetics of DOM adsorption in the ferrallitic soils can be divided into the two stages: fast and slow reactions,it could be better fitted by first-order model;(2) the adsorption isotherms of DOM on ferrallitic soils could be better fitted by Freundlich equation,indicating the adsorption process was a physical multilayer adsorption process;( 3) for different soils,the adsorption capacity of DOM was listed as follows: rhodic ferralsol > haplic ferralsol > paddy soil,for example,adsorbing capacity of compost DOM was up to 594. 906,309. 317 and 206. 316 mg / kg in the initial concentration of 50 mg / L,positively correlated with CEC,free iron oxide,free aluminium oxide and clay content,while negatively correlated with sand content;(4) for different DOMs,higher hydrophobic DOM had the larger adsorption capacity,which listed as follows: compost DOM( H-DOM) > soil DOM( M-DOM) > straw DOM( L-DOM);(5) for different DOM components,the adsorption capacity decreased as follows: hydrophobic neutrals( HON) > acid-insoluble matter( AIM) > hydrophobic bases( HOB) > hydrophobic acids( HOA) > hydrophillic matter( HIM),and the chain structure of aliphatic alkanes and higher aromaticity in DOM were the key factors influencing adsorption capacity as revealed by fourier-transform infrared spectroscopy( FT-IR);(6)the contribution to DOM adsorption by different fractions was the result of their adsorption capacities and contents. For different hydrophobic DOM,hydrophobic matter's contribution( HO) was more than HIM,up to 69. 43%85. 08%. For different polar fractions,H-DOM: HOA( 40. 24%) > HON( 39.10%) > HIM( 14.92%) > AIM( 3.82%) > HOB( 1.88%); L-DOM: HOA( 33. 50%) > HIM( 30. 57%) > HON( 24. 81%) > AIM( 7. 45%) > HOB( 3.68%);( 7) The presence of native DOM in soil impeded the exotic DOM adsorption by soil,especially for high hydrophobic DOM.
Batch experiments and XAD resin were used to investigate the adsorption of dissolved organic matter(DOM) by ferrallitic soils. The effects of soil properties and DOM characteristics on the adsorption were also studied to reveal the adsorption mechanism. The results showed that:(1) ferrallitic soils were high in DOM adsorption capacity,which increased with initial DOM concentrations,and the kinetics of DOM adsorption in the ferrallitic soils can be divided into the two stages: fast and slow reactions,it could be better fitted by first-order model;(2) the adsorption isotherms of DOM on ferrallitic soils could be better fitted by Freundlich equation,indicating the adsorption process was a physical multilayer adsorption process;( 3) for different soils,the adsorption capacity of DOM was listed as follows: rhodic ferralsol > haplic ferralsol > paddy soil,for example,adsorbing capacity of compost DOM was up to 594. 906,309. 317 and 206. 316 mg / kg in the initial concentration of 50 mg / L,positively correlated with CEC,free iron oxide,free aluminium oxide and clay content,while negatively correlated with sand content;(4) for different DOMs,higher hydrophobic DOM had the larger adsorption capacity,which listed as follows: compost DOM( H-DOM) > soil DOM( M-DOM) > straw DOM( L-DOM);(5) for different DOM components,the adsorption capacity decreased as follows: hydrophobic neutrals( HON) > acid-insoluble matter( AIM) > hydrophobic bases( HOB) > hydrophobic acids( HOA) > hydrophillic matter( HIM),and the chain structure of aliphatic alkanes and higher aromaticity in DOM were the key factors influencing adsorption capacity as revealed by fourier-transform infrared spectroscopy( FT-IR);(6)the contribution to DOM adsorption by different fractions was the result of their adsorption capacities and contents. For different hydrophobic DOM,hydrophobic matter's contribution( HO) was more than HIM,up to 69. 43%85. 08%. For different polar fractions,H-DOM: HOA( 40. 24%) > HON( 39.10%) > HIM( 14.92%) > AIM( 3.82%) > HOB( 1.88%); L-DOM: HOA( 33. 50%) > HIM( 30. 57%) > HON( 24. 81%) > AIM( 7. 45%) > HOB( 3.68%);( 7) The presence of native DOM in soil impeded the exotic DOM adsorption by soil,especially for high hydrophobic DOM.
基金
Supported by the National Natural Science Foundation of China(41371465)
