Adsorption of dissolved organic matter on ferrallitic soils
Batch experiments and XAD resin were used to investigate dissolved organic matter (DOM) adsorption 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 had high DOM adsorption capacity,which increased with initial DOM concentrations.The kinetics of DOM adsorption in the ferrallitic soils can be divided into the two stages:fast and slow reactions,and it could be better fitted by frist-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 follows the order of rhodic ferralsol ＞ haplic ferralsol ＞ paddy soil,adsorbing capacity of compost DOM was up to 594.9 mg· kg-1 in the initial concentration of 50 mg·L-1,it positively correlated with CEC,free iron oxide,free aluminium oxide and clay content,while negatively correlated with sand content;(4) for different DOMs,more hydrophobic DOM had the larger adsorption capacity,which follows the order of 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 capacity and content.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 (39.1％) ＞ 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 exogenous DOMs in soil impeded the exogenous DOM adsorption by soil,especially for more hydrophobic DOM.
NETL
NSTL
万方数据
维普
