胡杨年轮记录的塔里木河下游54年来区域水环境历史变迁

通过胡杨（Populus euphratica Oliv．）树木年轮宽度的分析，建立了塔里木河下游大西海子（A）、阿克墩（B）、亚合甫马汗（c）、英苏（D）、阿布达勒（E）、喀尔达依（F）、吐格买莱（G）、阿拉干（H）、依干不及麻（I）和考干（J）10个采样区过去54a来的STD、RES和ARS年表，并借助RES年表，采用年代际变化分析和突变检验，反演了塔里木河下游54a年来区域水环境状况变迁时空格局。结果表明：①下游10个样区54a来区域水环境状况具有多样性和复杂性，并不完全表现为距离下游上段（大西海子水库）越近其水环境状况就越好，区域水环境状况总体变异程度由低到高排序为A、G、C、H、E、D、I、B、F、J，也反映了下游10个样区生态退化程度的差异；②下游54a来区域水环境状况最好时期出现在20世纪60年代和21世纪初，大部分区域最差时期主要集中在20世纪90年代，是下游地区长达30a断流水环境变干累积效应的体现；③下游10个样区区域水环境变化具有明显的突变时间，突变出现时间相对水文事件年代具有滞后性。胡杨年轮记录的塔里木河下游54a来区域水环境时空变迁格局对下游生态退化的历史认识具有重要意义。

Change of regional water environment of the lower reaches of Tarim River recorded in Populus Euphratica tree ring width in the past 54 years

The characteristics of tree-ring width index sequence (RES chronologies) of Populus euphratica in the lower reaches of Tarim River were studied through the interannnal change analysis and the abrupt change examination. The ten sampling sites in-eluded Daxihaizi(A), Akedun(B), Yahepumahan(C), Yengisu(D), Abdale(E), Kardayi(F), Tugemailai(G), Argan(H), Yiganbujima(I) and Kaogan(J). The research reappeared the change pattern of regional water environment of the lower reaches of Tarim River in the past 54 years. The results indicated: ①The regional water environmental change of the ten sampling sites was various and compli-cated in the river downstream. The water environmental condition did not display completely that the nearer to the upper reaches (Daxihaizi reservoir) the site was, the better its water environmental condition was. The ascending series of the water environmental variation was A, G, C, H, E, D, I, B, F, J and reflected degree of ecology degeneration of the downstream ten sampling areas were different;② the best periods of water environmental conditions appeared in the 1960s and at the beginning of this century, and that the worst periods occurred mainly in the 1990s. This phenomenon was attributed to the breaking flow of river downstream for more than 30 years;③the abrupt change examination indicated that the water environmental change of the downstream ten sampling areas had the obvious sudden change effect. The emergence time of every abrupt change point was later than corresponding hydrology event. Recognizing the tree-ring width index change is important to understand the history of ecology degeneration in the lower reaches of Tarim River.