低潮位降雨及其径流对淤泥质潮间带颗粒物输运的影响研究综述

Review of the effects of low-tide rainfall-runoff on the particle transport in intertidal zone

低潮降雨及其径流能够扰动淤泥质潮间带表层沉积物并夹带极大量颗粒物输入潮间带水体,这一过程被视为潮间带物质循环的"热点",近年来备受关注。本文综合1978年至2018年针对降雨及其径流扰动和输运淤泥质潮间带物质的文章,阐释降雨在淤泥质潮间带物质输运过程中的作用及其导致的生态效应。这些研究发现降雨之所以能扰动和夹带沉积物首先是因为低潮期的雨滴冲击可以破坏并排出黏性沉积物,而后续形成的径流则向下坡方向转移被扰动的沉积物;其次,低潮降雨通常导致淤泥质潮间带径流中悬浮颗粒物浓度增大两倍以上,最高甚至增大到100倍,而潮汐和浅水波扰动则不能产生类似的效应;再次,附着在颗粒物上的有机质和金属等物质成分会出现与颗粒物浓度相一致的响应过程;最后,被降雨扰动的颗粒物在潮汐的输送下可能通过潮沟-潮下带系统从潮间带净输出至近岸水体。总而言之,在全球变化大背景下极端降雨事件趋于增加,因此降雨及其径流对淤泥质潮间带物质循环的影响应更加引起人们的关注。

Low tide rain drops directly suspend surfacial particulates of intertidal environment, and the following runoff facilitate the mobilization of substantially amounts of particles to the water column. These processes have been proposed as "hot moments". In order to demonstrate the influences of rainfall-runoff on the particle cycling and its ecological effects, rainfall related research papers between 1978 and 2018 were reviewed in this paper. These studies suggest that raindrops at low-tide destroy and discharge viscous surface sediments, and then the subsequent runoff transfers the resuspended sediments downhill. These processes lead to 2-100 times increase in suspended sediment concentrations of tidal creek water column, which is substantially higher than that of shallow water waves and tidal currents. Meanwhile, concentrations of organic matter and heavy metals correspond to the temporal dynamic of the suspended particulate matter. Finally,suspended particles driven by rainfall-runoff have great chances to export to the coastal ocean by tidal current and hereby contribute to the "Outwelling" processes. This issue is particularly relevant because global climate models highlight an intensification of the hydrologic cycle in many coastal areas. Therefore, the potential for low-tide rainfall to influence intertidal zone biogeochemical processes can be expected to increase, and therefore, a more comprehensive understanding of rainfall-runoff effects on intertidal landscape material cycling is needed.