摘要
采用红壤(pH=4.46)和潮黄土(pH=7.10)在氮气(N2)覆盖下进行淹水恒温((25.0±0.5)℃)培养.红壤在淹水60d后pH上升到5.92,潮黄土在淹水3d后pH降至6.62,然后再上升到6.89.2种土壤的pe+pH从14.16下降到5.38.pH和pe+pH的升降导致了土壤固相交换态(Exc-)、碳酸盐结合态(Carb-)、氧化物结合态(Oxide-)、有机质结合态(Org-)Fe再分配比例的增长,并使Exc-Cd向Carb-Cd、Oxide-Cd、Org-Cd转化.土壤Exc-Cd与Exc-Fe之间,Exc-Cd与(Carb-Cd+Oxide-Cd+Org-Cd)、(Carb-Fe+Oxide-Fe+Org-Fe)之间均显著负相关,由此表明,Fe组分的再分配决定着Cd组分的再分配.Fe、Cd的形态分配还影响着液相中Fe、Cd的浓度.在红壤淹水的1～7d中,固相中Cd以Exc-Cd为主,液相中Cd的浓度随pe+pH的下降而增加;在红壤淹水的中后期及潮黄土的整个淹水期,固相中Cd以Carb-Cd和Oxide-Cd为主,液相中Cd的浓度随pe+pH的下降而下降.淹水土壤中DOM对水溶性Cd浓度的影响不显著.
Cadmium activity in soils may vary considerably under submerged conditions, yet the mechanisms are not well understood. In this study, a red soil （pH = 4.46） and a fluvo-aquic soil （pH = 7.10） were submerged and incubated under a nitrogen atmosphere at constant temperature （ （25.0 ± 0. 5） ℃ ） to study the variation of Cd activity. The pH increased to 5.92 after 60 days for the red soil and decreased to 6.62 after 3 days and then rose to 6.89 for the fluvo-aquic soil. The pe ＋ pH for both soils decreased from 14.16 to 5.38. The variation of pH and pe ＋ pH caused the Fe redistribution in exchangeable （Exc-） , carbonate-bound （Carb-）, oxide-bound （Oxide-） and organic matter-bound （Org-） fractions, and transformation of Exc-Cd to Carb-, Oxide- and Org-Cd. The negative correlations were significant or highly significant between Exc-Cd and Exc-Fe, as well as between Exc-Cd and （ Carb-Cd ＋ Oxide-Cd ＋ Org-Cd） or （ Carb-Fe ＋ Oxide-Fe ＋ Org-Fe）, indicating that Fe redistribution controlled Cd redistribution in the soil solid phase and also affected the concentrations of Fe and Cd in soil solution. During the first 7 days following flooding in the red soil, Exc-Cd was the major fraction in the solid phase and the Cd concentration in the solution phase increased as the pe ＋ pH decreased. From days 15 to 60 after submergence for the red soil and over the whole incubation period for the fluvo-aquic soil, Carb-Cd and Oxide-Cd were the dominant forms in the solid phase. The soluble Cd concentration declined as pe ＋ pH decreased. Dissolved Organic Matter （DOM） did not significantly affect Cd solubility in the submerged soils.
出处
《环境科学学报》
CAS
CSCD
北大核心
2009年第2期373-380,共8页
Acta Scientiae Circumstantiae
基金
中国科学院南京土壤研究所土壤与农业持续发展国家重点实验室开放基金项目(No.0751010005)~~
