[Effects of oxalate on acid phosphatase adsorption and its activity on soil colloids and minerals].
By a batch method, this paper studied the effects of different concentration and pH of oxalate, an important root exudate, on the adsorption of acid phosphatase and its activity on < 2 microm colloids of yellow brown soil and latosol, and on minerals goethite and kaolinite. The results showed that the acid phosphatase adsorption by goethite was less affected by the concentration of oxalate; while the adsorbed amount of this enzyme by the other test colloids and kaolinite was sharply decreased with the increasing oxalate concentration (0-5 mmol x L(-1)) first, and then gradually increased to the level equal to or less than the blank, which may be related to the coordination type of oxalate on soil colloids and minerals, and their surface charge change and dissolution. In the systems oxalate existed, the adsorbed amount of acid phosphatase by soil colloids and minerals decreased in order of goethite >> yellow brown soil > kaolinite > latosol. The pH value for the maximum adsorption of acid phosphatase was between the IEP of the enzyme and the PZC of test colloids and minerals. After the enzyme was immobilized on colloids and minerals, the pH of its maximum specific activity had no change, or shifted to a higher value.
Zhao
Zhenhua
Z
College of Environmental Science and Enginning, Hehai University, Nanjing 210098, China. 2zh4000@mail.tom.com
Huang
Qiaoyun
Q
Jiang
Xin
X
Wang
Daizhang
D
Gao
Hongjian
H
Li
Xueyuan
X
D000135:Acid Phosphatase / Q000378:metabolism*; D000327:Adsorption; D003102:Colloids / Q000032:analysis; D008903:Minerals / Q000032:analysis; D010070:Oxalates; D012987:Soil / Q000032:analysis*
D003102:Colloids; D008903:Minerals; D010070:Oxalates; D012987:Soil; D000135:Acid Phosphatase