Fate and Trophic Transfer of Rare Earth Elements in a Tropical Estuarine Food Web

We sampled abiotic and food web components in an impacted estuarine system to assess the transfer and fate of rare earth elements (REE). REE (based on dry weight) were measured in sediments, suspended particulate matter (SPM), and organisms from different trophic levels. The highest n-ary sumation REE concentrations were measured in sediments (180 & PLUSMN; 4.24 mg kg-1) and SPM (163 & PLUSMN; 12.6 mg kg-1). Phytoplankton (45.7 & PLUSMN; 5.31 mg kg-1), periphyton (51.6 & PLUSMN; 1.81 mg kg-1), and zooplankton (68.5 & PLUSMN; 1.27 mg kg-1) are the major sources of exposure and transfer of REE to the food web. REE concentrations were several orders of magnitude lower in bivalves, crustaceans, and fish (6.01 & PLUSMN; 0.11, 1.22 & PLUSMN; 0.18, and 0.059 & PLUSMN; 0.003 mg kg-1, respectively) than in plankton. The n-ary sumation REE declined as a function of the trophic position, as determined by functional feeding groups and delta 15N, indicating that REE were subject to trophic dilution. Our study suggests that the consumption of seafood is unlikely to be an important source of REE for humans. However, given the numerous sources of dietary introduction of REE, they should be monitored for a possible harmful cumulative effect. This study provides new key information on REE's baseline concentrations and trophic transfers and patterns.

Automated summary

We studied the transfer and fate of rare earth elements (REE) in an impacted estuarine system by sampling abiotic and food web components. The highest concentrations of n-ary sumation REE were found in sediments and suspended particulate matter (SPM). Phytoplankton, periphyton, and zooplankton were identified as the major sources of REE exposure and transfer to the food web. The concentrations of REE in bivalves, crustaceans, and fish were much lower than in plankton, indicating trophic dilution. The study suggests that seafood consumption is unlikely to pose a significant risk of REE exposure for humans.