喀喇昆仑山至昆仑山地区湖水溶解氧特性分析

本文根据喀喇昆仑山至昆仑山地区湖泊考察中获得的资料,分析了溶解氧及其饱和度与湖水温度、矿化度及湖面海拔高程的关系,并探讨了这些因素对溶解氧日过程及垂直变化的综合影响。     

江苏省主要湖泊的降水量与湖泊的降水效应

本文分析了江苏境内主要湖泊的降水量特征,揭示了长江是江苏各湖泊不同降水量特征的一条十分明显的天然界线;估算了太湖的降水效应,并据此推估出江苏主要湖泊的降水效应不太明显;江苏各湖泊的降水量与其水位年过程趋势相似,只是后者位相滞后于前者而已。     

贡湖及其相关水域风生流模拟研究

在太湖风生流的数值模拟研究的基础上，设计模拟贡湖及其相关水域风生流的套网格数值模式。应用该模式研究不同风情下，梅梁湖，太湖主体湖水对贡湖的影响。     

青藏高原中部湖泊沉积物中Zr/Rb值及其环境意义

由于青藏高原及其周边地区构造复杂,湖泊沉积物中的粒级差别很大,单一的测量方法往往难以奏效。Rb、Zr是表生地球化学过程中的稳定元素,但它们之间也存在显著差别,Rb一般富集在细颗粒中,Zr则在粗颗粒中含量较高。研究发现,湖泊沉积物中Zr/Rb比值与粘土(<2μm)含量存在显著相关,Zr/Rb值反映了湖泊沉积物的粒度大小。Zr/Rb比值所揭示的青藏高原中部280万年来经历的3次大的环境演化过程与岩性变化、孢粉指标反映的环境特征是一致的。     

运城盆地11 kaBP以来气候环境变迁与湖面波动

通过黄土区湖泊沉积研究来恢复古气候、古环境，是对黄土区古气候、古环境研究的补充和检验。通过山西运城盆地硝地湖泊沉积物的多环境代用指标分析，结合史料记载，探讨了该地区11kaBP以来古气候演化和湖面波动的历史。结果表明，该地区存在YD（Younger Dryas）事件，进入全新世后气候有显著的趋势，最高湿润度发生在7．88－5．15和5kaBP后，气候逐渐变干，湖面波动与气候波动相关，全新世早期湖面开始上升，湖泊扩张，5kaBP后湖泊萎缩，盐类结晶析出。     

δ^13C-δ^18O Covariance： An Effective Indicator of Hydrological Closure for Lakes？

The correlation between theδ~(13)C andδ~(18)O in primary carbonates is affected by several factors such as hydrological balance,total CO_2 concentrations,climatic condition and lake productivity. The influence of these factors on theδ~(13)C-δ~(18)O correlation may be different on different time scales.In this paper,two different-type lakes in southwestern China,Lake Erhai and Lake Chenghai,are selected to investigate the influence of climatic pattern on theδ~(13)C-δ~(18)O correlation and to evaluate the reliability of theδ~(13)C-δ~(18)O covariance as an indicator of hydrological closure.The results show that there exists good correlation between theδ~(13)C andδ~(18)O in Lake Erhai (overflowing open lake) and in Lake Chenghai (closed lake).This suggests that theδ~(13)C-δ~(18)O covariance may be not an effective indicator of hydrological closure for lakes,especially on short time scales.On the one hand,a hydrologically open lake may display covariantδ~(13)C andδ~(18)O as a result of climatic influence.The particular alternate warm-dry and cold-wet climatic pattern in southwestern China may be the principal cause of theδ~(13)C-δ~(18)O covariance in Lake Erhai and Lake Chenghai.On the other hand,a hydrologically closed lake unnecessarily displays covariant trends betweenδ~(13)C andδ~(18)O because of the buffering effect of high CO_2 concentration on theδ~(13)C shift in byper-alkaline lakes.We should be prudent when we use the covariance betweenδ~(13)C andδ~(18)O to judge the hydrological closure of lake.     

岷江上游第四纪叠溪古堰塞湖的演化

采用岩性相和沉积体系的分析方法对岷江上游流域的阶地进行了研究．发现叠溪较场到太平村以北约28km的沿江河段内断续分布有湖相沉积。对太平村一带的三级阶地沉积识别出冲积扇沉积体系、湖泊沉积体系、河流沉积体系和风成、表生沉积体系。认为古堰塞湖发育2期高湖平面,其间存在低湖面期形成的古土壤层。根据最高湖泊沉积与堵江滑坡体的顶部高度对比和堰塞湖发育的时间计算,太平村地区相对叠溪校场地区存在着平均3．18m／ka的抬升运动。     

青藏高原腹地湖泊沉积对第四纪晚期古季风变化的响应

通过对青藏高原腹地的综合科学考察和对中心钻孔岩芯剖面的最新研究,用层序地层学与年代地层学和气候地层学相结合的方法,分辨出可可西里地区湖泊沉积记录(孔深7.25 m)的第四纪晚期距今3万余年以来的古气候变化,沉积物磁化率等因子综合表征的高原古季风变化是波动发展的,发生在仙女木期地质环境事件中的季风活动具有强烈暴发的特点,是高原季风发展中的突变事件,而且地表热点效应对其起到了激发作用。综合分析的研究成果表明,它的变化频谱与激变因子及其运行机制是伴随着青藏高原地质效应的演变而发展的,为研究第四纪冰消期以来的气候变化提供了新的信息。     

Weathering and climate change since l820 AD in Hoh Xil, Qinghai-Xizang Plateau, China——Evidence from element geochemistry of lake sediments of Gulug Co Lake

Element geochemistry of lake sediments has been widely used to detect climate change because element composition and ratios can reflect the weathering degree in the source area. Given the dement composition of lake sediments from Gulug Co Lake, Hoh Xil, Qing- hai-Xizang Plateau, chemical index of alteration （CIA）, index of composition variability （ICV） and other element ratios have been used to establish the weathering sequence of this area since 1820 AD. The weathering is so weak that the element composition change is more sensitive to climate change and autochthonous processes. From 1820 to 1984 AD, there were two drier periods with a wetter interval from 1870 to 1945 AD. After 1984 the weather showed a tendency of becoming wet.     

Measurement of the total nitrogen in lake sediments： Comparison and its environmental significance

Nitrogen cycle is an important bio-geochemical process in the environment. Measurement of the total nitrogen （TN） is a routine experiment in agriculture, biology and environmental sciences. The Kjeldahl method （KM） and elemental analyzer method （EA） are both commonly used to determine TN. Total nitrogen by EA is the sum of nitrate （NO3）, nitrite （NO2）, organic nitrogen and ammonia. Total nitrogen by KM （TKN） is made up of both organic nitrogen and ammonia. A comparative study focused on the two methods is conducted by analysis of TN in 97 samples from the sediment sequence of Gouchi, a salt lake in North China. KM presents a higher degree of accuracy than EA with a standard deviation of 0.007 vs. 0.024. With the presence of nitrate and/or nitrite nitrogen, however, measurement by KM is considerably lower than that by EA. Therefore, for samples from lake sediment sequences or soils in North China, KM is inapplicable to determining TN because of usually high contents of nitrous salt. Despite the inconsistency, use of both methods to the same samples makes sense in reconstructions of climatic and environmental changes from lake sediments. In Lake Gouchi, the contents of nitrate and nitrite nitrogen vary from 1.40% in the lower part of the sequence to 14.77% in the uppermost part, suggesting a gradual evolution process from a fresh water lake to the present-day salt lake.