生物活动对黄河口潮滩表层沉积物扰动作用的研究

A Study of the Effects of Bioturbation on the Surface Sediments in the Yellow River Estuarine Intertidal Zone

以螃蟹扰动作用下黄河口刁口地区潮滩表层沉积物为例,对沉积物的物理力学性质及其运移进行了试验研究,结果表明:螃蟹扰动作用使表层20 cm以内沉积物的含水率明显增加,渗透性略有提高,表层30 cm以内土体贯入强度降低,下层土体贯入强度增高;螃蟹每日掘出的细粒物质达502.08 g/m2(干重),远大于螃蟹洞穴在涨落潮过程中所捕获的细颗粒物质,并使潮滩表层沉积物细化。从螃蟹扰动对沉积物组成、性质和运移产生的作用,可以得出生物活动对黄河口潮滩的稳定性具有一定的影响。

The effects of bioturbation on sediments are increasingly gaining attention. A case study of burrowing crab effects on the surface sediments in the Yellow River Estuarine intertidal zone has been made. The burrowing crab activities of digging burrows impact sediment physical and mechanical features and sediment transportation. The study finds that the crab activities increase the water content and hydraulic conductivity of the sediments, but decrease the cone penetration strength value within 30 cm of the surface sediments and increase it below 30 cm. The funnel shapes of the burrows are always open, and they effectively trap clay and silt during spring and ebb tide. Crabs turn over large amounts, of sediments, up to 502.08 g/m^2·d （dry）, which is more than the amount of the sediments trapped. These sediments make the surface sediments mean grain size smaller. The crab behavior impacts sediment composition, sediment features, sediment transportation and the stability of the Yellow River Estuarine intertidal zone.