HR3DHG version 1: modeling the spatiotemporal dynamics of mercury in the Augusta Bay (southern Italy)

Giovanni Denaro,Mario Sprovieri,Bernardo Spagnolo,Enza Quinci,Andrea Cucco,Alessandro Borri,Andrea De Gaetano,Davide Valenti,Daniela Salvagio Manta,Maria Bonsignore

doi:10.5194/gmd-13-2073-2020

Abstract

Abstract. The biogeochemical dynamics of Hg, and specifically of its three species Hg0, HgII, and MeHg (elemental, inorganic, and organic, respectively), in the marine coastal area of Augusta Bay (southern Italy) have been explored by the high-resolution 3D Hg (HR3DHG) model, namely an advection–diffusion–reaction model for dissolved mercury in the seawater compartment coupled with a diffusion–reaction model for dissolved mercury in the pore water of sediments in which the desorption process for the sediment total mercury is taken into account. The spatiotemporal variability of the mercury concentration in both seawater ([HgD]) and the first layers of bottom sediments ([HgDsed] and [HgTsed]), as well as the Hg fluxes at the boundaries of the 3D model domain, have been theoretically reproduced, showing acceptable agreement with the experimental data collected in multiple field observations during six different oceanographic cruises. Also, the spatiotemporal dynamics of the total mercury concentration in seawater have been obtained by using both model results and field observations. The mass balance of the total Hg species in seawater has been calculated for the Augusta Harbour, improving previous estimations. The HR3DHG model could be used as an effective tool to predict the spatiotemporal distributions of dissolved and total mercury concentrations, while contributing to better assessing hazards for the environment and therefore for human health in highly polluted areas.

Highlights

The investigation of the biogeochemical dynamics of Hg species in the marine environment addresses the need to accurately model sources and pathways of this priority contaminant within and among the different abiotic and biotic compartments of the aquatic ecosystem (Driscoll et al, 2013; Batrakova et al, 2014)
The biogeochemical dynamics of Hg, and of its three species Hg0, HgII, and MeHg, in the marine coastal area of Augusta Bay have been explored by the high-resolution 3D Hg (HR3DHG) model, namely an advection–diffusion–reaction model for dissolved mercury in the seawater compartment coupled with a diffusion–reaction model for dissolved mercury in the pore water of sediments in which the desorption process for the sediment total mercury is taken into account
Denaro et al.: HR3DHG version 1 retical studies have offered innovative tools to reproduce the mass balance and the dynamics of [Hg] in the marine environment by means of biogeochemical models based on interconnected zero-dimensional boxes representing water or sediment compartments: among these are the River MERLINExpo model (Ciffroy, 2015) and the WASP (Water Analysis Simulation Program) model (Melaku Canu et al, 2015; Canu and Rosati, 2017; Rosati et al, 2018)

Summary

Introduction

The investigation of the biogeochemical dynamics of Hg species in the marine environment addresses the need to accurately model sources and pathways of this priority contaminant within and among the different abiotic and biotic compartments of the aquatic ecosystem (Driscoll et al, 2013; Batrakova et al, 2014). G. Denaro et al.: HR3DHG version 1 retical studies have offered innovative tools to reproduce the mass balance and the dynamics of [Hg] in the marine environment by means of biogeochemical models based on interconnected zero-dimensional boxes representing water or sediment compartments: among these are the River MERLINExpo model (Ciffroy, 2015) and the WASP (Water Analysis Simulation Program) model (Melaku Canu et al, 2015; Canu and Rosati, 2017; Rosati et al, 2018). The box model approach has been adopted in a 2D configuration (Melaku Canu et al, 2015; Canu and Rosati, 2017) to calculate Hg mass balance in the coastal areas of the Marano–Grado lagoon (northern Italy), where heterogeneous spatial distributions of Hg species have been observed experimentally. Models based on zero-dimensional boxes do not deliver reliable concentration values of contaminants in highly heterogeneous environments unless they provide high spatial resolution and a proper parameterization of the biogeochemical system

Results

Discussion

Conclusion