【摘要】 分析了贺兰山地区油松树轮的稳定碳氧同位素组成对环境因素的响应关系,发现树轮碳氧同位素组成均与当年5～9月总降水量具有较好的响应关系,碳同位素组成与5～9月总降水量呈负相关关系,而氧同位素组成与5～9月总降水量呈正相关关系,二者都可较好地反映该地区夏季风降水量的变化。同时,碳氧同位素的相关性分析表明二者具有一定程度的负相关性。树轮碳氧同位素的分馏机理十分复杂,其同位素组成不仅与降水量有关,同时还受其他环境因素的影响,单纯利用一种同位素指标来提取相应的气候信息,存在很大的不确定性。在本研究中,同时采用两种同位素指标来研究其气候意义,使得出的结论更加可靠。因此,夏季风降水量是控制该地区树轮稳定碳氧同位素组成的主要因素。更多还原

【Abstract】 Oxygen and carbon isotopic compositions of tree ring are affected by climatic factors. By studying the relationship between isotope ratios in tree r ing cellulose and climatic parameters, it is found that both the stable carbon a nd oxygen isotopic compositions of tree ring in Mt. Helan is significantly corre lated with the amount of growing seasonal precipitation from May to September. T he oxygen isotopic composition of the tree ring is in direct proportion to preci pitation amount, while the carbon isotope is in inverse to precipitation amount. Our results show that growing seasonal precipitation is the dominative factor f or both oxygen and carbon isotopic compositions of tree ring in arid and semi-a rid northwestern China. It is concluded that combining of the stable carbon and oxygen isotope ratios of tree ring can provide reliable proxy of paleoprecipitat ion for the arid and semi-arid area.更多还原