Density and conductivity properties of Na−CO3−Cl−SO4 brine from Mono Lake, California, USA

Relationships among conductivity, temperature, total dissolved solids (TDS), and density were determined for hypersaline brine (TDS, 83 g kg⁻¹) from Mono Lake. A theoretical estimate of density based on ionic composition and calculated partial molar volumes compared well with actual measurements (difference, 390 ppm). However, an empirically derived equation of state based on temperature and conductivity provides the most accurate density estimates (residual errors, 190 ppm) and can be used with data collected with CTD profilers.     

新疆乌尊布拉克东部干盐湖成盐环境和成盐年代的初步研究

新疆乌尊布拉克盐湖是我国目前少见的含钾硝酸盐型盐湖。文中根据资料和ＣＫ９６—１钻孔剖面中(１４)Ｃ年龄以及岩性的变化,粗略地探讨第四纪晚更新世末期大约４万年以来新疆乌尊布拉克盐湖沉积特征、成盐环境和大致年代。     

我国湖泊沉积环境演变研究中元素地球化学的应用现状及发展方向

全球气候恶化,洪涝、风沙、干旱等自然灾害频繁,科学研究预测区域乃至全球环境演变趋势,并采取有效措施加以防治,成为目前全人类面临的一大课题。要科学的掌握环境变化的规律,就必须研究过去的环境变迁,沉积物无疑是最好的研究对象。而湖泊在其发生发展过程中,直接出露于地表,其沉积物则是最好记录环境变化信息的载体。近几年来元素地球化学在研究湖泊演变历史,揭示湖泊环境变迁等方面取得了很大的进展。根据目前的研究现状,今后的工作应着眼于分析研究引起源泊环境变化的原因,环境演变与人类活动的关系及其演变规律,进而对未来环境演变趋势进行预测和对自然灾害进行防治,或许是今后湖泊沉积物元素地球化学研究的主要方向。     

青土湖近6000年来沉积气候记录研究--兼论四五世纪气候回暖

对青土湖志云村剖面沉积气候记录和湖泊进退进行了研究,证实季风边缘区河西走廓东段存在暖湿,冷干气候变化的阶段性特征。根据湖相沉积的颜色,粒度,化学组成和有机质含量等气候代用指标的综合分析,提出公元四五世纪存在一次百年尺度上的气候回暖,这一气候回暖事件的发现,可得到历史文献记录和青海湖自然记录的佐证。     

民勤湖区水资源与农业发展浅析

本文从湖区水资源现状出发, 论述了水、盐碱是湖区发展农业生产的主要限制因素。探讨了地下水利用, 因水种植与土地弃耕和轮歇以及储水灌溉定额等问题。提出了解决水的措施; 干旱、盐碱、风沙应统筹考虑, 农林牧水综合治理的观点。建议从有限的水资源中拨出一定数量的水用于种草种树。     

东海西湖凹陷平北地区表层沉积物特征及其成因初探

对研究区域的３７０个站位,１０８４个样品进行了粒度分析,对其中的部分样品进行了重矿物、古生物的分析和鉴定,发现东海西湖凹陷平片地区表层改造砂的特征与一般的规律有较大的差别,这种独特的表层沉积物特征的形成原因主要和所处的地貌部位有关。     

Geology and evolution of lakes in north-central Florida

 Fluid exchange between surficial waters and groundwater in karst environments, and the processes that control exchange, are of critical concern to water management districts and planners. High-resolution seismic data were collected from 30 lakes of north-central Florida. In each case study, lake structure and geomorphology were controlled by solution and/or mechanical processes. Processes that control lake development are twofold: (1) karstification or dissolution of the underlying limestone, and (2) the collapse, subsidence, or slumping of overburden to form sinkholes. Initial lake formation is directly related to the karst topography of the underlying host limestone. Case studies have shown that lakes can be divided by geomorphic types into progressive developmental phases: (1) active subsidence or collapse phase (young); (2) transitional phase (middle age); (3) baselevel phase (mature); and (4) polje (drowned prairie) – broad flat-bottom that have one or all phases of sinkhole. Using these criteria, Florida lakes can be classified by size, fill, subsurface features, and geomorphology. Received: 28 July 1998 · Accepted: 9 September 1998     

Seasonal variation in the biogeochemical cycling of seston in Grand Traverse Bay, Lake Michigan

This study describes the biogeochemical cycling of seston in Grand Traverse Bay, Lake Michigan. Seston was characterized by carbon and nitrogen elemental and isotopic abundances. Fluorescence, temperature, light transmittance, and concentrations of dissolved inorganic nitrogen were also determined. PCBs were analyzed from surface (10 m) seston and ΣPCB was calculated by summing all of the congeners quantified in each sample. The vertical and seasonal trends in the δ¹³C values of seston exhibited a broad range from −30.7 to −23.9‰. Low δ¹³C values that occur concurrently with a peak in fluorescence below the thermocline reflect uptake of ¹³C depleted respiratory CO₂ and/or the accumulation of ¹³C depleted lipids by phytoplankton. High δ¹³C values late in the season likely result from a reduction in photosynthetic fractionation associated with a decrease in the CO₂ pool. Seasonal δ¹⁵N values of seston were high in the spring and declined through August. The δ¹⁵N values of seston reflect a balance between fractionation during assimilation of NH₄⁺ or NO₃⁻ and degradative processes. The seston ΣPCB and fluorescence were both high in the spring and subsequently declined, suggesting that the concentrations of PCBs in seston were associated with labile material derived from primary productivity. The strong seasonal trends in the organic geochemical characteristics of seston and concentrations of PCBs emphasize the complex nature of particle cycling in aquatic environments.     

洪湖网簖数量调查和渔获物分析

利用卫星遥感定点技术,估算洪湖１９９３年初约有１１０００部网簖,洪湖网簖可分为“稀阵”,“密阵”两种。１９８６年稀阵渔获物中,乌鳢,鲤、鲇,草鱼等大中型鱼类的比例达４７．６％,１９９２￣１９９４年这些鱼类的比例不到７％,１９８６年鲫,红鳍三各小型鱼类的比例为５１．０％,１９９２￣１９９４年达８７．６％。九十年代洪湖主要经济鱼类的捕捞规格进一步下降,为此应地网簖渔业实施管理。     

9711号台风对太湖水位影响分析

针对１９９７年８月出现的９７１１号台风,就其对太湖水位的影响作了分析,分析表明,这次台风对太湖东西两岸水位影响显著东岸以减水为主,水位降幅达０．６６－０．９３ｍ,西岸以增水为主,增幅达０．６７－０．７７ｍ,水位振幅达－０．６７－１．２２ｍ,同一时间内,东西两岸水位差达１．１７－１．４２ｍ。分析还表明,太湖风场变化与水位变化关系较为紧密,表现为：当风向相对一致时,背风岸望亭,胥口的水位随风速的增加而