酸化及化学修复剂对森林土壤有机物淋溶的影响

选择我国重庆典型的酸化森林土壤,针对自然酸沉降条件下以及投加2种碱性化学修复剂(石灰石和菱镁矿)后土壤溶液中的溶解性有机物(DOM)动态变化展开观测,研究土壤酸化和化学修复对森林土壤碳库的潜在影响.为期3a的研究表明,修复剂加入后,由于土壤溶液pH值迅速升高,凋落物层DOM的淋溶在较短时间内有明显升高,但是这种效果难以持久;同时,投加修复剂后矿质土壤DOM的浓度显著降低,上层土壤溶液的DOC浓度由对照样地的(20.32±3.19)mg·L-1分别降低到石灰石样地的(15.69±2.39)mg·L-1和菱镁矿样地的(11.44±1.87)mg·L-1.矿质土壤溶液的DOC浓度可能与土壤溶液pH值呈负相关关系,与离子强度呈正相关关系.因此从长期来看,修复剂加入不会引起凋落物层有机质向矿质土层加速迁移,并可缓解由于酸化而导致的土壤有机物加速淋溶和碳库降低.

Effects of Acidification and Liming on Organic Matter Leaching in Forest Soil

The potential effects of acidification and liming on the dynamics of carbon pool in forest soil were studied through field experiments at Tieshanping, Chongqing in Southwest China. The changes of dissolved organic matter (DOM) concentration in soil water in different layers within three years after application of limestone or magnesite indicated that soil remediation had leaded to significant decrease of DOM in soil water from mineral layers e.g., DOC concentration in the upper layer decreased from (20.32 +/- 3.19) mg x L(-1) in the reference plots to (15.69 +/- 2.39) mg x L(-1) in limestone plots and (11.44 +/- 1.87) mg x L(-1) in magnesite ones] as probably the results of increasing pH value and decreasing ion strength, although the DOM leaching from the litter layer was found increasing, especially in the first half year. Consequently, liming may not in longterm accelerate the transport of soil organic mater downward from the litter layer to the mineral layer, but prevent the acidified soil from DOM-leaching and thus carbon-pool losing.