Estuarine sediment resuspension and acidification: Release behaviour of contaminants under different oxidation levels and acid sources

Abstract

Carbon dioxide (CO) Capture and Storage (CCS) is a technology to reduce the emissions of this gas to the atmosphere by sequestering it in geological formations. In the case of offshore storage, unexpected CO leakages will acidify the marine environment. Reductions of the pH might be also caused by anthropogenic activities or natural events such as acid spills and dredging operations or storms and floods. Changes in the pH of the marine environment will trigger the mobilisation of elements trapped in contaminated shallow sediments with unclear redox boundary. Trace element (As, Cd, Cr, Cu, Ni, Pb and Zn) release from anoxic and oxic estuarine sediment is analysed and modelled under different laboratory acidification conditions using HNO (l) and CO (g): acidification at pH = 6.5 as worst-case scenario in events of CO leakages and acid spills, and acidification at pH = 7.0 as a seawater scenario under CO leakages, acid spills, as well as sediment resuspension. The prediction of metal leaching behaviour appear to require sediment specific and site specific tools. In the present work it is demonstrated that the proposed three in-series reactions model predicts the process kinetics of the studied elements under different simulated environmental conditions (oxidation levels and acid sources). Differences between HNO and CO acidification are analysed through the influence of the CO gas on the ionic competition of the medium. The acidification with CO provokes higher released concentrations from the oxic sediment than from the anoxic sediment, except in the case of Zn, which influences the release of the other studied elements. Slight acidification can endanger the aquatic environment through an important mobilisation of contaminants. The obtained prediction of the contaminant release from sediment (kinetic parameters and maximum concentrations) can contribute to the exposure assessment stage for risk management and preincidental planning in accidental CO leakages and chemical spills scenarios.

Sunscreens as a New Source of Metals and Nutrients to Coastal Waters

“…The correlation coefficient ( R 2 ), relative standard deviation (RSD), and relative and absolute error were used to check the validity of the model. This tool has been successfully used previously by the authors to model release behavior of contaminants from sediments to seawater. , The model parameters were adjusted using an NL2SOL algorithm for the least-squares minimization of the deviation between the experimental and theoretical data.…”

“…This tool has been successfully used previously by the authors to model release behavior of contaminants from sediments to seawater. 23,24 The model parameters were adjusted using an NL2SOL algorithm for the least-squares minimization of the deviation between the experimental and theoretical data.…”

Impacts of the combined exposure to seawater acidification and arsenic on the proteome of Crassostrea angulata and Crassostrea gigas

“…10048-95-0) was directly spiked into aquaria to achieve a final concentration of 500 μg As L −1 . Arsenic exposure concentration was chosen considering: i) previous studies that showed sublethal effects of As to adult oysters (Zhang et al, 2015a;Moreira et al, 2016); median effect concentrations to oyster embryo-larval development (Martin et al, 1981;Mamindy-Pajany et al, 2013;Moreira et al, 2018); iii) data on As concentrations in the water column from suspended particulate matter (260 mg kg −1 , Ereira et al, 2015), and considering that OA increases the bioavailability of elements (Martín-Torre et al, 2017;Zeng et al, 2015).…”

“…In fact, recent research demonstrated that OA may alter the bioavailability of inorganic contaminants such as metal(loid)s (Zeng et al, 2015), by increasing the relative amount of free metal form, given that pH influences the adsorption properties of these elements with dissolved organic matter, carbonate ion, sulphide, and iron (oxy)hydroxide minerals. OA is therefore expected to increase metal bioavailability, thus potentially increasing element uptake by organisms (Martín-Torre et al, 2017). Such interactions become most relevant in highly dynamic ecosystems such as estuaries, which function as major sinks for contaminants.…”

Modelling geochemical and kinetic processes involved in lead (Pb) remobilization during resuspension events of contaminated sediments

“…Laboratory resuspension experiments are helpful to mimic and predict the remobilization of TM occurring during in situ sediment resuspension and to test the influence of particles concentrations or kinetics of chemical reactions. Results of resuspension experiments in numerous works show kinetic evolutions of TM concentrations in the dissolved phase, and competition phenomenon for the adsorption of TM on the solid suspended particles (Saulnier and Mucci, 2000;Caille et al, 2003;Camino Martin-Torre et al, 2017;Monnin et al, 2018). The evolution of TM concentrations in water are thus controlled by both rapid and slow release and uptake processes.…”