Seasonal changes in Porteresia coarctata (Tateoka) beds along a subtropical coast

Shoot density, standing crop (above- and below-ground biomass) and habitat of salt marsh grass Porteresia coarctata were investigated along the coast of Bakkhali estuary, Cox’s Bazar, Bangladesh from January to December 2006. Shoot density of P. coarctata was influenced by season and was found to be higher (>2 500 shoots/m 2 ) in post-monsoon and minimal in monsoon season; plants were particularly active in vegetative propagation during pre-monsoon. Above-ground biomass was greater along the protected coast compared with the exposed one in this estuary. Below-ground biomass was higher (7.75-269.53 g DW/m 2 ) than that above ground (2.20-114.75 g DW/m 2 ). Standing crops of P. coarctata showed a negative relationship (R=-0.77; P<0.05) with sedimentation rate, while seasonal activity influenced sedimentation. The recorded sedimentation rate was lower (6.09 mg/(cm 2 ·d)) in pre-monsoon and highest (14.55 mg/(cm 2 ·d)) in monsoon season. The mean value of pore water salinity was higher (34.25±5.05) during post-monsoon and lowest (18.0±3.71) in monsoon season. The soil was sandy clay in this P. coarctata bed; it consisted of 86% sand, 13% clay and 1% silt. Soil organic matter dropped during the monsoon season (0.78%-0.67%) and was highest ((2.17±1.42)%-(2.3±1.47)%) during post-monsoon, probably owing to accumulation of decomposed peat on the marsh surface. The mean pore water NH 4 -N concentration ranged from 2.44±1.65 to 3.33±1.82 μg/L, with a minimum air temperature of 22.09°C in post-monsoon and a maximum of 31.16°C in pre-monsoon. Variations of physico-chemical parameters in the soil, water, and climate governed biological parameters of P. coarctata in the Bakkhali estuary, and were comparable with estuarine environments elsewhere.     

塔里木沙漠公路沿线不同地下水埋深下的土壤水盐分布特征

通过在塔里木沙漠公路沿线选取3个不同地下水埋深区域（地下水埋深分别为3 m、7.3 m、13.7 m）取样并测定土壤含水率和含盐量,分析了地下水埋深对于土壤水盐分布的影响。结果表明：不同地下水埋深处土壤含水率随深度增加均先减小后增大,盐分的变化相对比较复杂;砂土最大毛细上升高度大约为1.8 m;黏土层具有聚水积盐的作用,其分布处含水率和含盐量都比较大;灌溉水影响深度为1.2 m。研究结果充分考虑了地下水埋深在土壤水盐分布中起的重要作用,在相关研究中具有重要的参考意义,对于建立合理的灌溉制度具有重要的指导意义。     

四川盆地地下卤水勘探开发前景展望

四川盆地地下卤水分布广泛,点多面广,品质优良,资源丰富,开发历史悠久。卤水含有K+、Br-、I-、B3+、Li+、Sr2+等多种有用组分,为重要的化工原料水。进一步加强四川盆地卤水资源研究,对卤水有利构造或地段进行勘探开发,必将为振兴四川卤化工业,实施西部大开发战略作出贡献。     

金属镁生产工艺进展

简要介绍了工业上镁的生产方法——热还原法和电解法;对热还原法和电解法的优缺点进行了讨论;概述了皮江法和电解法在改进方面所取得的新进展。     

微波炉法测定遗址土含水率的可靠性研究

古代土遗址病害发展与土的含水率变化密切相关,但土遗址保护现场快速准确测定土的含水率不是一件容易的事。选择遗址土、含盐土、黄土等进行对比试验,研究分析微波炉烘干法（简称微波炉法）测遗址土含水率结果的可靠性。在测定试验土样界限含水率和易溶盐含量的基础上,对比分析微波炉法、烘箱法两种方法测定土含水率的误差来源。试验结果表明,土的塑性对微波炉法的测定有一定影响,但测定误差均在2%以内;土的含盐量影响水分的蒸发速度,不影响微波炉法的测定结果;微波法测定遗址土含水率准确,且具有快速、便捷等优势,值得在土遗址保护工程中推广使用。     

盐膏层造斜井段井眼缩径及套管外载数值模拟

盐膏层是油气成藏的良好盖层,塔里木盆地多个大型油气藏都属于巨厚盐下油气藏,为了提高单井产能,决定采用定向井和水平井来开发盐下油气藏。由于盐膏层距离产层较近,需要在盐膏层进行造斜。造斜井段盐膏层井眼的缩径规律及其对套管外载的影响国内外鲜有报道。应用有限元方法建立了造斜井段砂岩和盐膏岩地层、水泥环及套管耦合的三维力学模型,以塔里木羊塔克区块岩石力学测试成果为基础,研究得到造斜段井斜和方位对井眼缩径及套管外载的影响规律。该研究成果成功应用于塔里木巨厚盐下定向井、水平井轨迹设计,钻遇盐膏层泥浆密度的确定和井身结构设计,为塔里木盐膏层钻井、完井施工提供了重要的理论参考。     

盐穴储油（气）库水溶造腔管柱动力特性初探

针对盐穴储气库单井水溶造腔过程中管柱动力特性开展了初步探讨,认为造腔工程中,管柱在受限空间的自激振动和动力失稳是导致管柱发生严重弯曲或者破损的主要原因。初步分析了无空间约束条件下内外管柱的振动特性,得到了理想条件下管柱临界流速的计算式。计算表明,无约束条件下造腔管柱一般会由于液-固耦联振动而发生动力失稳,而且造腔内管一般会先于造腔外管发生失稳破坏。鉴于问题的重要性和复杂性,还对造腔管柱临界流速全面计算力学模型应考虑的诸因素进行了探讨,初步分析了管道轴力、液体压力、造腔循环方式、管道水平支撑,以及轴向水击和管道横向振动耦合的影响,为进一步结合工程实际开展空间约束条件下造腔管柱动力特性全面分析提出了建议。     

On the potential of plant species invasion influencing bio‐geomorphologic landscape formation in salt marshes

Species invasions are known to change biotic and abiotic ecosystem characteristics such as community structure, cycling of materials and dynamics of rivers. However, their ability to alter interactions between biotic and abiotic ecosystem components, in particular bio‐geomorphic feedbacks and the resulting landscape configuration in tidal wetlands, such as tidal channels have not yet been demonstrated. We studied the impact of altered bio‐geomorphic feedbacks on geomorphologic features (i.e. tidal wetland channels), by comparing proxies for channel network geometry (unchanneled flow lengths, fractal dimension) over time between non‐invaded and invaded salt marsh habitats. The non‐invaded habitats (the south of eastern Chongming Island, Yangtze estuary, China) show little change in network geometry over time with a tendency for an increased drainage density. The invaded site (salt marshes in the north of eastern Chongming Island invaded by the exotic plant species Spartina alterniflora) showed a decreasing tendency in channel drainage density throughout and after the species invasion. This suggests that species invasions might not only affect biotic ecosystem characteristics, but also their ability to change bio‐geomorphic feedback loops, potentially leading to changes in existing geomorphologic features and therefore landscape configuration. Our results further suggest that the species invasion also altered sediment composition. Based on observations we propose a mechanism explaining the change in channel drainage density by an alteration in plant properties. The physical and physiological characteristics of the invading species Spartina alterniflora clearly differ from the native species Scirpus mariqueter, inducing different bio‐geomorphic feedback loops leading to the observed change in salt marsh channel configuration. Copyright © 2016 John Wiley & Sons, Ltd.     

盐岩地下储气库体积收敛失效概率分析与模型试验验证

盐岩地下储气库受盐岩蠕变特性影响会产生较大的体积收缩变形,影响储气库安全稳定运行。目前对地下储气库体积稳定性分析方法和评价准则各国没有统一标准,国内主要采用数值计算的方法来评价储气库体积稳定性。以江苏金坛盐矿地下储气库体积收敛数值分析为基础,借鉴国外盐岩地下储气库稳定性评价标准,建立盐岩地下储气库体积收敛失效风险评价矩阵,采用一次二阶矩法显示功能函数分析储气库体积收敛失效概率,分析得出：储气库在长期恒定内压工况下体积收敛失效概率随内压的增大而减小;在短期调峰低压工况下体积收敛失效概率随内压的减小而增大;最小内压应保持在4.2 MPa以上。通过交变气压条件下层状盐岩地下储气库大型三维地质力学模型试验得出:储气库体积收敛变形随内压的增大而减小;短期运行最小内压应大于4.0 MPa。模型试验结果与失效概率分析结论较为相似。因此,为避免盐岩地下储气库产生体积收敛破坏,应保证调峰短期最小内压在4.0 MPa以上。