This paper analyzes the grain-size distribution of surface sediments of the Chanthaburi coast of Thailand to investigate the sedimentary environment and its evolution to better use and protect the coast. The Flemming triangle method, the grade-standard deviation method, and the Gao–Collins grain-size trend analysis method (GSTA model) were used to study the dynamic sedimentary environment of the area and provide preliminary identification of source materials. There are seven types of surface sediments on this coast, with grain sizes (φ) generally consisting of sand and silt. Sorting is generally poor, and becomes gradually poorer with distance offshore. Skewness is generally positive. The study area is mainly composed of sand and silt, indicating that the hydrodynamics are strong. The results of grade-standard deviation analysis indicate that sediment grain size b (3.25–4.5φ) is a sensitive indicator of environmental change. This sediment type exhibits a relatively complex transport trend, mainly characterized by northwestward and northeastward transport from sea to land. Sediments at the mouth of the Chanthaburi Estuary and the Welu River fluctuate under the influence of tidal currents. Based on the results of grade-standard deviation analysis and grain-size trend analysis, the study area was divided into three provinces, representing different sedimentary environments and material sources. Compared with tidal-controlled estuaries in the temperate regions of eastern China, the two tropical estuaries examined in this study exhibited smaller suspended sediment loads, runoff amounts, and tidal ranges. However, hydrodynamic conditions were generally stronger. The main reasons for the similarities and differences in the transport trends of sediments in these estuaries were differences in hydrodynamic conditions and the specifics of regional topography.

The data of the identification of diatoms in surface sediment samples from the inner shelf of the East China Sea, are presented here. This data were collected during three surveys: one in winter 2008 and two in summer 2009, i.e., before and after the passage of Typhoon Morakot. Diatom identification was performed using an optical microscope (Olympus BX51). For detailed analysis, explanation, and discussion, the reader is referred to "The influence of season and Typhoon Morakot on the distribution of diatoms in surface sediments on the inner shelf of the East China Sea" Chen et al, 2019. Slides of all samples are held at the Third Institute of Oceanography of the Ministry of Natural Resources in Xiamen (P.R. China).

Diatoms are an important component of submarine biogenic sediments and often used for carrying out palaeoceanographical reconstructions. To understand the relationship between diatoms and environment in the western equatorial Pacific, diatoms from the Holocene sediments in the northern West Caroline Basin were selected for analysis. We made quantitative statistics on diatoms and divided diatom assemblages through cluster analysis. A total of 53 species or varieties of diatoms belonging to 22 genera were identified. The range of diatom abundance was 0-88,373 valves/g. The diatoms found were mainly oceanic warm-water species. Overall, Azpeitia nodulifera was the species with the highest contribution, followed by Hemidiscus cuneiformis and Thalassiosira pacifica with these three species together accounting for approximately 80% in this area. We identified four diatom groupings and divided the study area into three regions. Diatom assemblage I in the West Caroline Basin was mainly affected by the North Equatorial Counter Current (NECC), Antarctic Intermediate Water (AAIW) and upwelling, and the supply of nutrients was relatively high. Assemblage II in the West Caroline Ridge was less influenced by currents, and thus had lower abundance and species diversity than assemblage I. The complex diatom assemblages in the Yap Trench were probably controlled by Upper Circumpolar Deep Water (UCPW) and Lower Circumpolar Deep Water (LCPW).