东江流域土壤、植被和悬浮物的碳、氮同位素组成

碳、氮同位素值对监测流域植被组成、环境变迁是一种非常有效的指标,为中短时间尺度环境变化研究提供了一条新的途径。以亚热带山区的东江流域为例,以流域内的植被、土壤及水体悬浮物为研究对象,应用其有机质同位素组成（δ13C、δ15N）,揭示流域植被的成分和环境变化的信息。研究发现：东江流域土壤碳同位素、C/N比值差值不大;植被的氮同位素差值明显,C/N比值差异较大。对东江流域悬浮物δ13C值近20年的监测表明：其值在早期逐年升高,近10年来转趋稳定并呈明显下降趋势,变化范围在-17.8‰～-26.1‰之间,反映了该流域植被破坏和恢复的过程以及土壤侵蚀状况的变化趋势。

Carbon and nitrogen stable isotope composition of soil,vegetation and suspended sediment in Dongjiang river basin

Carbon and nitrogen stable isotope composition（δ 13 C,δ 15 N）are effectual indicators for monitoring vegetation and environmental change,which offer a new method to observe the environmental change in a short-medium scale.This paper analyzes δ 13 C,δ 15 N and C/N ratios in Dongjiang river basin and reveals the vegetation and environmental changes in this region.Results indicated thatδ 13 C and C/N ratios of soils were not very different,butδ 15 N and C/N ratios of vegetations had an apparent difference. Theδ 13 C of suspended sediment gradually became＂partial positive＂in 1990’s but＂partial negative＂in recent years.The carbon sta-ble isotope composition ranged from-17.8 to-26.1‰,which reflected the change trend of soil erosion,vegetation disruption and recovery in Dongjiang river basin.