沉积物捕获器在海岸与陆架沉积动力研究中的应用:以罗源湾和台湾海峡为例

Applications of sediment trap in sediment dynamics in coast and shelf seas:A case study of Luoyuan Bay and Taiwan Strait

运用时间序列的沉积物捕获器对海岸与陆架海域沉降颗粒物进行采集，估算沉降通量，并运用多学科综合研究手段分析沉降颗粒物的来源、组成、时空变化及控制因素，可以为海岸与陆架沉积动力过程的研究提供新的研究手段。福建罗源湾的实验表明，夏季罗源湾潮下带小潮至中潮期间的沉降通量为133．20～256．18 g／（m2·t）；由中潮向大潮变化期间单个潮周期的沉降通量明显增大，台风过后的大潮期间的沉降通量为373．99～590．51 g／（m2·t）；台风显著影响期间的沉降通量为746．34 g／（m2·t）；粒度分析及水动力观测结果显示，观测期间罗源湾潮下带沉降颗粒物主要来源于海底沉积物的再悬浮。台湾海峡西北部内陆架海域的实验研究表明，该海域近底部悬浮颗粒物沉降通量最大值为13．34 g／（m2·d），由小潮向中潮沉降通量逐渐增大，这主要是由于近底部温盐跃层层位上移，近底部垂向混合作用增强，致使底部再悬浮沉积物向上扩散，并最终被沉积物捕获器捕获。沉积物捕获器可以接收到再悬浮沉积物，结合底部边界层过程的观测研究，可以深入认识海底沉积物的侵蚀、沉降及埋藏过程，在研究海岸与陆架区沉积动力学、泥质区沉积记录的形成过程与保存潜力中扮演着十分重要的角色。

Marine particles contain a lot of information on chemical,physical,biological processes in the interior of the ocean.Using time-series sediment trap for collecting the settling particles estimating the settling fluxes,and an-alyzing their sources,compositions and temporal and spatial variations and associated controlled factors by compre-hensive methods,can provide a new method for the research of sediment dynamic process in coast and shelf seas. Two experiments were carried out in Luoyuan Bay of Fujian Province and inner shelf in northwest Taiwan Strait in July,2012.The estimated settling fluxes of the experiment in Luoyuan Bay by cylinder trap increased from neap tide to spring tide.During the neap tide,the near-bed settling fluxes ranged from 133.20 to 256.18 g/（m2 .t）, while the values in spring tide ranged from 373.99 to 590.51 g/（m2 .t）,and the maximum value was 746.34 g/（m2 .t）which occurred at the early spring tide with strong effect of typhoon event.The results of grain size a-nalysis and hydrodynamic measurement indicated that the near-bed settling particles originated from surface sedi-ment resuspension.The maximum near-bed settling flux of the experiment in Taiwan Strait by cone trap during the observation was 13.34 g/（m2 .d）which occurred at neap tide,while the settling fluxes increased from inter-mediate tide to neap tide.During the middle-late stage of the measurement,the near-bed thermocline and halocline varied upward and the vertical mixture was enhanced,which led the resuspended sediment diffused upward and in-creased the settling flux ultimately.These two experimental results indicate that the sediment trap combined with the measurement of bottom boundary layer may play an important role in the research of sediment dynamic proces-ses,sediment record formation and preservation in the muddy deposited system in coast and inner shelf seas.