Analysis and health risk assessment of heavy metals in four common seaweeds of Marchica lagoon (a restored lagoon, Moroccan Mediterranean)

The Marchica lagoon (Morocco, Mediterranean) is a wetland classified as a RAMSAR site, which has been the subject of restoration activities after several years of pollution. The heavy metal (loïdes) content was studied in four common species of seaweed (Gracilaria sp., Alsidium corallinum, Caulerpa prolifera and Chaetomorpha sp.) for the first time, and was added to the basic studies carried out on sediments and water of this ecosystem. The heavy metals with mean values (mg/kg) can be sequenced in descending order, Al > Sr > Rb > Ba > As > Ti > V > Ni > Pb > Cr > Cd > Li > Co for Chaetomorpha sp., and the following order Al > Sr > As > Pb > Ti > Ba > Rb > V > Li > Cr > Co > Ni > Cd for Caulerpa prolifera. The mean concentrations (mg/kg) in Gracilaria sp. followed the sequence Al > Sr > Ti > Rb > Pb > As > Co > Ba > V > Ni > Cr > Li > Cd, and the following order Al > Sr > Ti > Rb > As > Ba > Pb > V > Co > Ni > Cr > Li > Cd in Alsidium corralinum. The Pb and As levels in studied seaweeds were above the CEVA standards. The health risk analysis showed that consuming the seaweed under study posed a serious risk. All examined seaweed had HI values greater than 1.0, and arsenic is the element that strongly contributes to these values, which can suggest a potential negative impact caused by this metalloid. Red seaweeds showed the highest MPI, followed by green seaweeds.