Environmental evolution in the salt-water intrusion area south of Laizhou Bay since late Pleistocene

The south coastal plain of Laizhou Bay is one of the typical salt-water intrusion areas in China, the occurrence and development of which was closely related with the palaeoenvironment evolution. Systematic analyses of pollen, foraminifera and grain size composition based on ^14C and luminescence dating from two sediment cores were performed for the purpose of understanding the salt-water intrusion in the coastal plain of Laizhou Bay from the perspective of environmental evolution since late Pleistocene. It could be classified into seven evolution stages since 120 kaBP： 120-85 kaBP was a transition period from cold to warm; 85-76 kaBP was a period with warm and wet climate having swamp lakes developed in the lower reaches of the Weihe River, south coastal plain of Laizhou Bay; 76-50 kaBP was characterized by grassland vegetation and coarse sediments in terrestrial environment, which was the early stage of Dali Ice-Age; 50-24 kaBP was a period with alternate sea deposition in the south coastal plain of Laizhou Bay; 24-10 kaBP was the late stage of Dali Ice-Age with coldest period of Quaternary, the south coastal plain of Laizhou Bay was dry grassland and loess deposition environment; 10-4 kaBP was another warm and wet climate period, sea level was high and regressed at 4 kaBP; and has been the modern sedimentary environment since 4 kaBP. Among the three warm stages, including 85-76 kaBP, 50-24 kaBP and 10-4 kaBP, corresponded to late Yangkou, Guangrao and Kenli seawater transgression respectively. The duration of the latter one in south coastal plain of Laizhou Bay was longer than that in west coast of Bohai Sea and east coast of Laizhou Bay. The three periods of seawater transgression formed the foundation of salt-water intrusion in this area.

Ground water hydrochemical characteristics: seawater intruded area in eastern and southern coast of Laizhou Bay

Eastern and southern coastal zones of Laizhou Bay are the most representative seawater intruded areas in the world, with two intrusion sources of contemporary seawater and paleobrine. In order to reveal the complicated hydrochemical changing process and the mechanism of fresh groundwater being polluted by saltwater, we conducted long-term observation and hydrochemical analysis at four observing sections of typical salt-fresh water transitional zone. The study indicates that seawater and brine intrusion processes have different hydrochemical features, and that ion exchange and adsorption actions between water and aquifer produce great influence on the intrusion.

Study on sea water intrusion into palaeochannels on south coastal plain of the Laizhou Bay by the Bohai Sea

The palaeochannel evolution in the study region is divided into four stages by such methods as 14C dating. Sea water intrusion through palaeochannels has been studied as a focal point. Palaeochannels are the main passageways through which the sea water intrudes at a higher speed, through many means and in a changeable dynamic state.

莱州湾南岸海水入侵现状评价

根据莱州湾南岸海水入侵区地下水水质特点,将海水入侵等级划分为4级。同时,选取Cl-,矿化度,SO42-,rHCO3-/rCl-,K-等指标作为评价因子,并分别确定了这5项指标的等级划分范围。然后,运用模糊数学的综合评判方法,对研究区内海水入侵现状做出评价。

莱州湾南岸土壤剖面盐分离子分异规律研究

莱州湾南岸地区受海水入侵影响盐渍化问题严重，土壤盐渍化是制约区域农业生产和发展的主要障碍因子。运用经典统计学和地统计学的方法，研究了莱州湾南岸地区土壤剖面盐分离子的空间分异规律。结果表明：土壤全盐含量随深度的增加而增加，表现出底聚趋势；各层土壤盐分离子均表现中等和强烈的变异性；土壤盐分主要以NaCl和Na2SO4的形式存在；偏相关分析说明不同盐分离子间的相关性差异较大；聚类分析表明盐分离子主要分为三大类：K＋、Mg2 、Ca2 和SO42-为第一类，Na 单独组成第二类，Cl-则为第三类；除全盐含量在30～60cm具有中等空间自相关外，其他各层土壤盐分属性均具有强烈的空间自相关性；盐渍化类型以硫酸盐型、氯化物—硫酸盐型和硫酸盐—氯化物型为主，盐渍化程度以轻度盐渍化为主。

莱州湾南岸地下咸/盐水资源开发设想

莱州湾南岸依托丰富的卤水矿藏发展起来了庞大的海洋化工产业体系,为地下咸/盐水资源的开发提供了潜在的产业基础。文章论述了将海水淡化技术引入盐浓度区间1 g/L^35 g/L地下咸/盐水开发过程的设想,并在此基础上论述了将大菱鲆养殖产业与之共生的可行性。最后,还讨论了将浓度区间35 g/L^50 g/L地下盐水输送盐田晒盐的合理性和必要性。