p_(CO_2)平面光极在生物扰动存在下水/沉积物体系中的应用

用内层包埋、外层覆盖的方法制备一种基于TOA+PTS4-离子对的pCO2平面荧光传感膜,并将该传感膜制备的pCO2平面光极系统应用于生物扰动存在的水/沉积物体系,通过连续监测体系垂直剖面pCO2的分布及变化,可得水/沉积物体系中pCO2的原位二维时空分布图.结果表明:在生物扰动作用下,体系中底层上覆水pCO2的变化较大,先上升后逐渐稳定;沉积物表层的pCO2边界扩散层逐渐消失,中层沉积物中pCO2基本不变,深层沉积物中pCO2先增大后逐渐稳定.体系中pCO2的变化是一个复杂的多维变化,涉及CO2产生和消耗的动态过程,是物理混合、颤蚓生命活动及有机质矿化等多种机制综合作用的结果.     

生物扰动下水/沉积物体系中pH,DO和p_(CO_2)的变化规律

利用平面光极技术,制备pH、溶解氧(DO)和CO_2分压(p_(CO_2))荧光传感膜,构建集3种膜于一体的水/沉积物模拟体系,并研究颤蚓扰动作用下体系中pH,DO,p_(CO_2)的二维分布与协同变化规律.结果表明:无生物扰动体系中上覆水和沉积物各参数变化较小;存在颤蚓扰动体系中各参数随时间变化均较显著,随着扰动时间延长,体系中pH,DO,p_(CO_2)呈均一化趋势;在有生物扰动的体系中,3个参数间存在一定的协同变化趋势并相互影响.     

基于平面光极技术研究颤蚓生物扰动对水中Cd2+向沉积物迁移的影响

制备了一种能够选择性识别Cd~(2+)的平面传感膜;该膜具有响应速度快(20 s)、准确性高及稳定性好等特点。利用该传感膜制备的Cd~(2+)平面光极系统,应用于生物扰动存在的水/沉积物体系中,根据体系垂直剖面Cd~(2+)的分布及迁移情况,研究颤蚓生物扰动对上覆水中Cd~(2+)向沉积物迁移的影响。研究发现:制备的Cd~(2+)平面光极系统可以反映出上覆水中Cd~(2+)向沉积物迁移的过程。无生物扰动时,沉积物仅表层及水/沉积物界面下2 cm深度范围内第1~3 d的Cd~(2+)浓度略有升高,随后趋于稳定;深度超过2 cm的沉积物Cd~(2+)浓度几乎不变(同背景浓度)。有生物扰动时,深度约5 cm范围内的沉积物中Cd~(2+)浓度显著增加,深度越浅的沉积物中的Cd~(2+)浓度增加越快,深度超过5 cm的沉积物中Cd~(2+)浓度基本不变。与无生物相比,颤蚓扰动可以显著促进Cd~(2+)由上覆水中向沉积物的迁移。     

Burrow morphology of the echiuran worm Maxmuelleria lankesteri (Echiura: Bonelliidae), and a brief review of burrow structure and related ecology of the Echiura

The burrow morphology of the echiuran worm Maxmuelleria lankesteri (Herdman) was investigated in situ using a resin casting technique. Work was carried out in Lochs Sween and Creran on the west coast of Scotland in predominantly fine mud sediments. Burrow casts typically had only 1 opening, although there is evidence to suggest that a second opening may exist. In 58% of burrows, the opening, which was small and funnel-shaped, was associated with a surface mound reaching up to 20 cm in height. The tunnel below the burrow opening, the ‘neck’, was narrow and circular in transverse section with a smooth wall, possibly due to the action of the mucus-laden proboscis which emerges during feeding. The maximum burrow depth recorded was 80 cm and tunnel orientation became more horizontal with increasing depth. In some larger burrows, the tunnel began to orientate upwards towards its end. Below the neck, the tunnel was much wider but had a sub-circular transverse section. The burrows had distinct striations on the walls of lower tunnels, possibly caused by movements of the animal within. In some cases, a community of symbiotic organisms had developed, including polychaetes and 2 species of bivalve, Mysella bidentata (Montagu) and Saxicavella jeffresii Winckworth. Evidence of burrow modification by the crustacean Jaxea nocturna Nardo was noted and gobies, including Gobius niger Linnaeus, were also responsible for some alterations to the upper burrow around the opening. Evidence suggested that burrows were permanent structures which changed little in position.     

颤蚓生物扰动对Cu和Cd从上覆水向沉积物迁移的影响

通过实验室模拟沉积物/水体系中颤蚓的生物扰动过程, 研究颤蚓密度和上覆水pH对颤蚓生物扰动效应及其对Cu和Cd向沉积物迁移速率的影响. 实验结果表明： 颤蚓扰动作用可显著提高Cu和Cd向沉积物迁移的速率, 且Cu受影响的作用大于Cd; 随着颤蚓密度的增加, Cu和Cd的迁移速率均增大; 酸碱胁迫均可促进生物扰动, 碱性条件下生物扰动作用更显著; 生物扰动促进的物质交换作用可显著增强实验体系对酸碱的缓冲能力, 使体系pH趋于中性、 均一; Cu和Cd的迁移速率同时受体系pH和扰动强度的影响, 总体随上覆水pH值的增大而增加; 生物扰动对Cd迁移的促进作用更大.