近地面O_3含量升高条件下土壤中腐殖质单体儿茶酚转化的放射性~（14）C示踪研究

近地面大气臭氧（O3）含量不断升高对生态环境的影响已引起人们的广泛关注,然而O3含量升高对土壤有机碳的矿化及转化影响却少有研究。土壤有机碳是全球碳循环的重要组成部分,土壤碳库的微小变化将引起大气CO2浓度的显著改变。文章以典型土壤腐殖质单体化合物儿茶酚为代表,利用14C示踪技术,研究了O3含量比当前背景升高约0.15μmol·mol-1时对土壤中腐殖质苯酚类前体化合物的矿化及转化的影响。结果表明,O3含量升高会对土壤中培育12d后儿茶酚的矿化及残留物分布具有显著的影响,而且这种影响程度和规律同土壤有关。O3含量升高促进了黄棕壤中儿茶酚的矿化,增加了儿茶酚残留物在黄棕壤腐殖酸（HA）中的总量,并使残留物在HA中偏向于同大分子结合。O3含量升高对灰潮土中儿茶酚的矿化有抑制作用,但对儿茶酚残留在HA内总量及分布没有显著影响。O3含量升高对儿茶酚在土壤中的稳定性及归趋的影响可能是O3对于微生物活性的抑制作用和O3的直接氧化作用的共同结果。后续工作中应研究土壤腐殖质中其它组份的稳定性及转化对近地面大气O3含量升高的响应,以全面考察O3含量升高对土壤碳库的影响。

The effect of atmospheric elevated O3 on the degradation of 14 catechol in the soil

The increasing amount of O3 in the atmosphere has caused international public and scientific concerns;however,little is known about the effects of the elevated O3 on mineralization and transformation of soil organic matter（SOM）,which is an important carbon pool in global carbon cycle.Small changes of the SOM stability can significantly affect the atmospheric CO2 concentration. Using uniformly ring-1 4C labeled catechol as a model compound of the humus phenolic compounds,we studied mineralization and transformation of phenolic precursors of humus in two soils（a yellow brown soil and a gray alluvial soil）under an elevated O3（0.15 μmol·mol-1 higher than the atmospheric O 3 ）.After incubation in the soils for 12 days under the elevated O3,mineralization of 14C-catechol in the yellow brown soil was significantly stimulated and the total amounts of 14C-catechol residues in humic acid fraction was increased.High performance-14 C-gel permeation chromatography showed that molecular size distribution of the residues within the humic acids was shifted to humic molecules with high molecular weights.In contrast,mineralization of 14C-catechol in the gray alluvial soil was significantly reduced and both the total amounts of 14C-catehchol residues in the humic acids and the molecular distribution of the residues within the humic acids were not significantly affected by the elevated O3.The results suggest that effects of the elevated O3 on stability of SOM depend on soil type and that different components of SOM might response differently,which needs further studied.