新疆石河子草滩湖湿地沉积物地球化学特征及其古环境分析

以新疆石河子草滩湖湿地作为研究地点,采用化学分析手段,获取该地区4 000 a B.P.以来有机质和总氮TN等数据,并结合孢粉数据,综合探讨古气候变化特征。在500-1 080 a B.P.和2 190-3 800 a B.P.期间,有机质和TN含量较高,此时气候较为湿润,泥炭累积;而在1 080-2 190 a B.P.期间,有机质和TN含量均处于剖面最低值,可能出现一次干旱事件,不利于泥炭堆积。湿地开垦为农田,其有机质和TN含量变化迅速减少,养分大量损失,可见开垦活动是引起湿地退化的原因之一。

Geochemical Characteristics and Its Paleoenvironment of Wetland Sediment in Caotanhu Wetland,Shihezi City in Xinjiang Province of China

Soil organic matter,total organic carbon(TOC) and total nitrogen(TN) are the important indexes to research the change of dry-moist palaeoclimate change and analyze the reason of the wetland degeneration.The Caotanhu wetland in Shihezi,which is located at the transitional zone between the middle section of Tianshan Mountains and the Junggar Basin in Xinjiang,is selected as the research area.Using the chemical analysis methods,the high resolution record of soil organic matter,TOC and TN data since 4 000 a B.P.was obtained.Combined with pollen data,the information of paleoclimate change was extracted.The results revealed during 500-1080 a B.P.and 2190-3800 a B.P.,soil organic matter and TN were at their higher values,suggesting that the climate became humid and the wetland developed with abundant freshwater aquatic plants,which contributed to the peat accumulation.But during 1080-2190 a B.P.,the lowest values of soil organic matter and TN indicated that a dry climatic condition was not favorable for the accumulation of peat.Once the wetland has been converted into farmland,the great loss in soil organic matter and TN happened,which indicates that human reclamation is one of reasons of the degradation of wetlands.