ABSTRACT
Most trace metal inputs to the Mediterranean come from rivers and major urban, port and
industrial centres. Despite numerous efforts, these inputs are continuing, while at the same time
changing with global changes: changes in river flows, emerging metals, new chemical forms.
These inputs and the risk they pose to coastal ecosystems have been studied on the French coast,
but for the southern shore of the Mediterranean there is currently very little information
available. Our study aims to define the flows and speciation of trace metals from the El Harrach
and Mazafran wadis in the coastal region of Algiers, as well as the current state and history of
marine sediment contamination.
Temporal monitoring of the waters of the El Harrach and Mazafran wadis was carried out during
twenty-four (24) sampling campaigns between August 2017 and July 2018, with a frequency
of bi-monthly sampling. At the same time, around thirty stations were sampled for surface
sediment opposite the mouths of the wadis. In addition, two sediment cores were taken in the
bays of Algiers and Marseille. Trace metals were measured in the water and sediment samples
using ICP-MS. The organic matter content and granulometry of the sediment samples were also
determined. TME fluxes were estimated, and the risk assessment of TSS and sediments was
carried out using an ecotoxicological approach based on the calculation of multiple indices.
The results of this study indicate that all the particulate metals analysed in the wadis come from
anthropogenic sources (EF > 1.5), with higher contamination of dissolved Pb, Cd, Zn and Ni
and a slight degree of contamination of particulate Cu and Zn (0 < Igeo < 1). A significant toxic
effect (ΣTUi >4) of the combined particulate metals (Pb, Cd, Cu, Zn, Cr, Ni and As) is observed
in both wadis. The results of this study also showed that surface sediments present a low
ecological risk for living species. Arsenic and mercury are the only metals with a potential
ecological risk. With the exception of arsenic, the other metals recorded higher concentrations
in Algiers Bay than in Bou-Ismail Bay. The mean RI value for the eleven trace metals in Algiers
Bay shows a severe ecological risk (RI = 306).
Key words: trace metals, continental inputs, contamination, marine sediment, coastal
ecosystem.
Most trace metal inputs to the Mediterranean come from rivers and major urban, port and
industrial centres. Despite numerous efforts, these inputs are continuing, while at the same time
changing with global changes: changes in river flows, emerging metals, new chemical forms.
These inputs and the risk they pose to coastal ecosystems have been studied on the French coast,
but for the southern shore of the Mediterranean there is currently very little information
available. Our study aims to define the flows and speciation of trace metals from the El Harrach
and Mazafran wadis in the coastal region of Algiers, as well as the current state and history of
marine sediment contamination.
Temporal monitoring of the waters of the El Harrach and Mazafran wadis was carried out during
twenty-four (24) sampling campaigns between August 2017 and July 2018, with a frequency
of bi-monthly sampling. At the same time, around thirty stations were sampled for surface
sediment opposite the mouths of the wadis. In addition, two sediment cores were taken in the
bays of Algiers and Marseille. Trace metals were measured in the water and sediment samples
using ICP-MS. The organic matter content and granulometry of the sediment samples were also
determined. TME fluxes were estimated, and the risk assessment of TSS and sediments was
carried out using an ecotoxicological approach based on the calculation of multiple indices.
The results of this study indicate that all the particulate metals analysed in the wadis come from
anthropogenic sources (EF > 1.5), with higher contamination of dissolved Pb, Cd, Zn and Ni
and a slight degree of contamination of particulate Cu and Zn (0 < Igeo < 1). A significant toxic
effect (ΣTUi >4) of the combined particulate metals (Pb, Cd, Cu, Zn, Cr, Ni and As) is observed
in both wadis. The results of this study also showed that surface sediments present a low
ecological risk for living species. Arsenic and mercury are the only metals with a potential
ecological risk. With the exception of arsenic, the other metals recorded higher concentrations
in Algiers Bay than in Bou-Ismail Bay. The mean RI value for the eleven trace metals in Algiers
Bay shows a severe ecological risk (RI = 306).
Key words: trace metals, continental inputs, contamination, marine sediment, coastal
ecosystem.