Comparative study on the bioaccumulation and biotransformation of arsenic by some northeastern Atlantic and northwestern Mediterranean sponges

Anna Maria Orani,Aurélie Barats,Wendy Zitte,Christine Morrow,Olivier P Thomas

doi:10.1016/j.chemosphere.2018.03.078

Abstract

The bioaccumulation and biotransformation of arsenic (As) were studied in six representative marine sponges from the French Mediterranean and Irish Atlantic coasts. Methodologies were carefully optimized in one of the species on Haliclona fulva sponges for two critical steps: the sample mineralization for total As analysis by ICP-MS and the extraction of As species for HPLC-ICP-MS analysis. During the optimization, extractions performed with 0.6 mol L−1 H3PO4 were shown to be the most efficient. Extraction recovery of 81% was obtained which represents the best results obtained until now in sponge samples. Total As analyses and As speciation were performed on certified reference materials and allow confirming the measurement quality both during the sample preparation and analysis. Additionally, this study represents an environmental survey demonstrating a high variability of total As concentrations among the different species, probably related to different physiological or microbial features. As speciation results showed the predominance of arsenobetaine (AsB) regardless of the sponge species, as well as the occurrence of low amounts of dimethylarsinic acid (DMA), arsenate (As(+V)), and unknown As species in some samples. The process responsible for As transformation in sponges is most likely related to sponges metabolism itself or the action of symbiont organisms. AsB is supposed to be implied in the protection against osmolytic stress. This study demonstrates the ability of sponges to accumulate and bio-transform As, proving that sponges are relevant bio-monitors for As contamination in the marine environment, and potential tools in environmental bio-remediation.

Highlights

Arsenic (As) is a ubiquitous element that ranks 20th in abundance in the earth’s crust (1.5–3 mg kg−1)
The bioaccumulation of trace elements in sponges was suggested to differ according to sponge species and the element of interest (Batista et al, 2014; Mayzel et al, 2014; Cebrian et al, 2007; Patel et al, 1985)
A two-steps method using HNO3 and H2O2 was reported in aquatic organisms such as algae, fishes, bivalves, crabs, and shrimps (Hong et al, 2014; Llorente-Mirandes et al, 2010), as well as in sponges and associated bacteria (Keren et al, 2017)

Summary

Introduction

Arsenic (As) is a ubiquitous element that ranks 20th in abundance in the earth’s crust (1.5–3 mg kg−1). Sponges are sessile filter feeders, capable of filtering every day a volume of seawater up to 50 000 times that of their body (Weisz et al, 2008) They have been recognized as excellent bio-monitors for trace element pollution (Perez et al, 2005; Cebrian et al, 2007) as they are capable to accumulate trace elements at concentrations higher than bivalves (Patel et al, 1985; Negri et al., 2006; Padovan et al, 2012). Sponges seem to accumulate more As than other marine organisms, which makes them suitable models for biomonitoring studies, as already proposed by

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