Dataset on the abundance, enrichment and partitioning of chemical elements between the filtered, particulate and sedimentary phases in the Cai River estuary (South China Sea).

This data article refers to the paper entitled "Multi-element signatures in solid and solution phases in a tropical mixing zone: A case study in the Cai River estuary, Vietnam" (Koukina et al., 2021), which considers the fate of major, trace, and rare-earth elements transported through the estuarine geochemical filter of the typical tropical estuary. The present work contributes to the local geochemical baselines as a background for long-term monitoring of potential hazardous elements. Therefore, the dataset covers the abundance, enrichment, and partitioning parameters of 53 chemical elements in the water, suspended particulate matter, and bottom sediment samples collected in the Cai River estuary and the adjacent part of the Nha Trang Bay (South China Sea) between July and August 2013. The total filtered, particulate, and sedimentary elements were determined by atomic emission and inductively coupled plasma mass spectrometry (ICP-AES; ICP-MS). The environmental indices (the enrichment factor and geoaccumulation index) and partition coefficients were calculated from the total element contents. The data provided is essential for the comprehensive environmental assessment of the anthropogenic impact on the coastal ecosystem as well as for the evaluation and modelling of element fractionation and mobility at the estuarine gradients.

Multi-element signatures in solid and solution phases in a tropical mixing zone: A case study in the Cai River estuary, Vietnam.

This study provides baseline concentrations of major, trace, and rare earth elements (REEs) in the solid and solution phases of the tropical Cai River estuary under influence of multiple stresses. The application of the selected multivariate analysis tools (principal component analysis and redundancy analysis) to the enrichment factor and partitioning coefficients (KSPM/Water and KSPM/Sed) calculated from the bulk element contents highlighted the strongest relationships (considered as multi-element signatures) according to the efficiency of the transfer across the estuarine gradients (considered as a selective geochemical filter). Thus, most of the major and trace elements, and REEs studied mainly settle within the mixing zone due to the association with terrigenous aluminosilicate clay minerals, whereas Co, Ni, Cu, As, and Mo are transferred seaward because of their association with the most labile fraction of the fluvial particulate load (such as clays, organic colloids, and carbonates). The major and trace elements, and REEs investigated in this study are mainly introduced in the Cai River and its estuary via basement rock weathering under enhanced monsoonal precipitation, whereas Bi showed the most severe enrichment in the non-weathering distribution pattern. The fractionation of the fluvial element load within the estuarine geochemical filter is mainly controlled by the differential settling of fluvial mineral element-bearing phases along with estuarine colloid dynamics - a topic that must warrants further investigation.

Dataset on optical characteristics and spectroscopic indices of dissolved organic matter of the Kara, Laptev, and East Siberian seas in August-September 2017.

A total of 137 water samples to study optical properties of chromophoric dissolved organic matter were collected in the Artic shelf seas during the 69th cruise on board the R/V Akademik Mstislav Keldysh in August-September 2017. Sampling sites were located in the Kara, Laptev and East Siberian seas and associated to the areas influenced by terrestrial runoff of the Kolyma, Indigirka, Lena, Khatanga, Ob and Yenisei rivers. In this data article, conventional spectroscopic indices and lignin phenol concentrations, calculated on the basis of fluorescence and UV-vis absorption spectra, are presented.