Study on the formation of mudflat and habitat of benthos due to mud transport in shallow water area

在这项研究中，利用自动升降仪器测量滩涂的水质，该仪器可以长期收集不同深度的水力数据和水质数据。对数据进行分析，重点关注悬浮物，揭示了不同潮汐时期悬浮物的变化和分布。从获得的测量结果中成功提取了有关滩涂各种物理特征波动的信息。阐明了水位变化下泥滩泥沙输移的一些特征。本研究还尝试考虑SS和营养盐的移动，从而研究它们的特性以及侵蚀对水质的影响。因此，可以说 T-N 和 T-P 在很大程度上取决于泥浆侵蚀行为。它们对水质有很大的影响，而在本次有限的调查中，DIN和DIP可能不会受到泥浆侵蚀的明显影响。另外，水体中被侵蚀物浸出的部分营养物质又被悬浮物吸附。利用沉积物收集器和观测塔对泥滩上悬浮物的行为进行了研究。沉降量和营养盐的分析结果揭示了泥滩沉降物质的特征。在沉积物防水布中观察到的沉降通量几乎与理论计算得到的净沉降通量一致。泥滩的沉降量也根据本研究中测量的沉降通量进行了估计。通过对三个塔的观测数据的检验表明，该区域存在细粘性泥沙输运现象。通过实验提取了缢蛏的偏好因子。由此，根据综合适宜性指数对缢蛉栖息地进行了估算。

In this study, water quality in a tidal flat is measured using an automatic ascending-descending instrument that collects hydraulic data and water quality data at various depths over a long period. Analysis of the data, focusing on suspended solids, reveals the variations and distribution of suspended solids in different tidal periods. Information regarding the fluctuation in various physical characteristics of tidal flats was successfully extracted from the obtained measurements. Some of the characteristics of sediment transport over mud flats under the variations of water level were also clarified. This research also attempts to consider that the movement of SS and nutrients, and thus their characteristics and the influence of erosion to water quality are investigated. As a result, it can be said that T-N and T-P are much dependent on the behaviors of mud erosion. They contribute a great effect to the water quality, while DIN and DIP may not be affected clearly by the mud erosion in this limited survey. In addition, parts of nutrients leached in the water from eroded matters were adsorbed to suspended matters again.Behaviors of suspended matters on the mud flat were investigated by using the sediment-traps and observation towers. Results obtained from the analysis of the amounts of sedimentation and nutrients reveal the characteristics of settling matters in the mud flat. The settling flux observed in the sediment-tarps almost coincided with the net settling flux obtained from a theoretical calculation. The amount of sedimentation to the mud flat was also estimated based upon the settling flux measured in this study. It is shown that the fine cohesive sediment transport in the area was demonstrated through examining the observed data in three towers.The preference factors of Sinonovacula constrica were extracted by some experiments. As the results, habitat of Sinonovacula constrica was estimated on the base of composite suitability index.