Rare-earth elements and yttrium distributions in mangrove coastal water systems: The western Gulf of Thailand

Abstract

The concentration of rare-earth elements and yttrium (REY) was investigated in dissolved phase, suspended particulate matter, and seafloor sediments of the western coastal area of the Gulf of Thailand. The samples show Eu and Gd positive anomalies in the shale-normalized REY patterns, especially in the suspended particulate matter. On the other hand, a very high REE content was detected in the coastal waters, probably due to the weathering produced by the Mae Klong river waters on rare-earth element (REE)-rich accessory minerals coming from terrains and mineral deposits cropping out in the studied area. The shale-normalized patterns of yttrium and REE estimated for the dissolved phase show an enrichment of medium rare-earth elements (MREE), characteristic of extensive water-rock interactions and weathering occurring in the continental environment. The REE concentrations of suspended particulate, normalized to the REE concentrations in each sediment sampled from the tidal flat, show the same behaviour of the experimentally determined apparent REE bulk distribution coefficients [1] for pH values ranging from about 5.5 to 6.2. Since the REY concentration of the water masses is controlled by the oceanographic features of the studied area, riverine inputs, and ionic straight, we suppose that the dissolved phase represents a mix of truly dissolved and colloidal pool (<0.2 µm) in which REY were enriched during the rock-water interactions of continental environment. In the estuarine system, the salt-induced coagulation of colloidal pool takes place and an authigenic fraction of suspended matter is formed, assuming the typical REE behaviour due to rock-water interactions.

Alteration effects of volcanic ash in seawater: Anomalous Y/Ho ratios in coastal waters of the Central Mediterranean sea

“…Trace element scavenging on an ion exchange resin was repeated five times to ensure their complete removal. The efficiency of this approach was demonstrated by Mö ller et al (1992) and Censi et al (2004Censi et al ( , 2005, and by the results obtained in this work (Table 1). A 500-ll aliquot of a standard solution of known YREE concentration was added to 5 l of the trace metals free seawater to yield an artificial seawater solution, hereafter referred to as SOL-1 (Table 1).…”

Recognition of water masses according to geochemical signatures in the Central Mediterranean sea: Y/Ho ratio and rare earth element behaviour

“…Analytical blanks were obtained with 50 ml of HNO 3 Merck ultrapure in Millipore ultrapure waters, and their concentrations were negligible compared with the measured REE concentrations. All methodologies were carried out as extensively described in previous publications [7,8,26]. …”

“…(1) recognize fractionation processes between dissolved and suspended phases [1][2][3][4] (2) examine the capability of REY to depict evidence of anthropogenic input in river and coastal waters, with a special emphasis on countries surrounded by highly populated areas [5]; (3) evaluate the mechanisms of input of these elements in the sea-water system for atmospheric or riverine loads [6][7][8].…”

State of rare earth elements in the sediment and their bioaccumulation by mangroves: a case study in pristine islands of Indian Sundarban

“…In addition, the variations of REE is related to complex estuarine-geochemical processes such as removal and fractionation primarily due to estuarine mixing (Sholkovitz 1990;Censi et al 2005;Santos et al 2007;Hannigan et al 2010), redox alteration in the water column (Bau et al 1997), anthropogenic impacts on sediments (Olmez et al 1991;Tranchida et al 2011;Perez-Lopez et al 2016;Brito et al 2018b), etc. Iron oxyhydroxides (FeOOH) and organic matter (OM) are known to have strong affinities with REE and play an important role in transfer and immobilization of REE.…”

“…Estuarine and coastal systems, particularly mangroves, are carbon-rich productive ecosystem (Duarte et al 2005). Clay and OM rich estuarine sediment can serve as repository of REE (Brito et al 2018a;Zhang et al 2013;Silva-Filho et al 2011;Prasad and Ramanathan 2008;Censi et al 2005). In contrast to estuarine sediment, little is known about the bioaccumulation, distribution, and fractionation pattern of REE within the complex halophytes like mangroves.…”