鼎湖山、尖峰岭和那大地区某些土壤的氧化还原状况

OXIDATION-REDUCTION REGIME IN SOME SOILS OF DINGHU/JIANFENG MOUNTAINS AND NADA REGION

用电化学方法测定了鼎湖山、尖峰岭和那大地区某些土壤的氧化还原电位(强度因素)和还原性物质数量(容量因素)。自然林下土壤的氧化还原状况随植物群落的垂直带(谱)而呈规律性变化。其表层的Eh为400—560mV,较以下土层低80—220mV,还原性物质含量相当于0.5—3.6×10^(-3)mol/L亚锰。经济林下土壤表层的Eh为490—570mV,较下层低50-100mV,还原性物质含量为0.1—1.36×10^(-3)mol/L。水稻土表层的还原性物质含量达6.6×10^(-3)mol/L,Eh为330mV,较下层低100mV。在还原性物质含量的对数值和Eh之间存在着良好的相关性,相关系数为-0.734^(**)。本文对用电化学方法原位测定弱还原性土壤的氧化还原状况给予了评价,对氧化还原过程在红壤形成中的作用进行了讨论。

The oxidation-reduction potentials (intensity factor) and reducing substances(capacity factor) in some soils of the Dinglu Mountain, the Jianfeng Mountain and the Nada region were determined in situ with ,electrochemical methods.It was found that the oxidatlon-reduction regime in soils changed regularly with the variation of the vertical plant community. Generally, the Eh values in the surface layers were 400—60 mV, which were 80—120mV lower than those in the lower horizons, and the amounts of reducing substances corresponded to0.5—3.6×10^(-5) molL^(-1) of Mn^(2+). Under economical trees, the Eh values in the surface layers ranged from 490 to 570mV, which were 50—100mV lower than those in the lower horizons, and the reducing substances were 0.1—1.36×10^(-5) moll^(-1). The amounts of redncing substances in the cultivated layers of paddy soils with a Eh of 330mV were up to 6.6×10^(-5) molL^(-1) of Mn^(2+), being 100mV lower than those in the lower horizons. There was a negative correlation between the Eh value and logarithm of the concentration of reducing substances, with a correlation coefficient of—0.734. A evaluation was made on the determination of oxidation-reduction regimes in the weakly reducing soils especially the natural and upland soils in situ by electrochemical methods and the role of oxidation-reduction processes in the formation of red soils was also discussed.