沼泽沉积剖面特征元素比值及其环境意义——盐碱化指标及气候干湿变化

Ratio of Elements and Their Implications Within Typical Sedimentation Profile in the Marsh—— Salinization Indicators and Climatic Change between the Arid and the Humid

沼泽发育过程中堆积的各类沉积物真实地记录下区域环境演变与沼泽发育过程的信息。以向海沼泽湿地为研究对象,由137Cs2、10Pb法定年实现沉积层深度坐标向年代坐标的转换,对典型沉积剖面特征元素比值进行了综合剖析。结果表明:Sr/Ba、Rb/K、(CaO+K2O+Na2O)/Al2O3等比值具有盐碱化和气候干湿变化的指示意义。该区域的盐碱化并非只发生在近几十年,而是由来已久,只是近年来人类活动促进了盐碱化进程。霍林河流域近240年来气候存在冷干—暖湿—冷干的多次波动,1880年之前气候以冷干为主,并有小幅度波动;1880年后气候开始转暖,但仍以冷暖波动振荡为主。

The Xianghai Wetlands Nature Reserve (122°05′-122°31′E, 44°55′-45°09′N) was situated in the western border of the Songnen Plain in Northeast China. It has been listed in the List of Wetlands of International Importance since 1992 (Ramsar site No. 548). As downstream freshwater wetlands of the Huolin River, the Xianghai Wetlands, covering an area of 360 km^2, located at parts of the semi-arid climatic zone and border with the Keerqin Desert. Except for rainfall, the main hydrological inputs (about 55.2%)of the Xianghai Wetlands were from the Huolin River. The Huolin River originated from the Da Hinggan Mountains, flowed about 320km, and lost its watercourse and end at the Xianghai riverine wetlands. Xianghai Wetlands were located at transition zones of terrestrial and aquatic ecosystems, where they received sediment inputs from both systems. Accumulative sediments during marsh development really recorded the region environment change and marsh processes. Here we reported a case study on the Xianghai marsh wetlands at downstream of an interior river—Huolin River. By segmented sample with centimeter and assorted with ^(137)Cs, ^(210)Pb age measure, high-resolution analyzed sediment element geochemistry in two typical sedimentation cores. Through analysis of ratios of elements in the typical sedimentation profile, the following results are revealed: the ratios of Sr/Ba, Rb/K, and (CaO+K_2O+Na_2O)/Al_2O_3 are good indicators to diagnosis salinization and climatic change between the arid and the humid. The salinization in this area not only is occurred in recent several decades, but is long-standing, however, human activities have enforced the progress and periods of salinization in recent years. Too much vibration has occurred between cool arid and warm humid during the recent 240 years in the Houlin River catchments.