Seasonal variability of metals (Fe, Cr and Ni) and physicochemical parameters in seawater and sediments of the Marchica lagoon (Northeast Morocco)

¹ OLMAN-BGPE, Pluridisciplinary Faculty of Nador, Mohammed First University, B.P 300, Selouane, 62700, Nador, Morocco
² Higher School of Technology of Nador, Mohammed First University, B.P 300, Selouane, 62700, Nador, Morocco

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

This study aims to characterize the seasonal variability of trace metals Fe, Cr, and Ni, and the state of physicochemical parameters in the seawater and sediments of the Marchica lagoon, focusing on the mouth of Selouane River and the New Pass areas. In the analyzed seawater samples, physicochemical parameters like temperature and salinity were significantly (p<0.05) higher in summer (28.17 °C and 36.00 PSU) than winter (22.17 °C and 33.67 PSU), whereas dissolved oxygen (DO) was significantly (p<0.05) higher in winter (8.73 mg/L) than summer (7.33 mg/L). In space, salinity and DO were significantly (p<0.05) higher in the New pass (Sal = 35.67 psu, and DO = 8.63 mg/L) than Mouth of Seloune River (Sal = 34 PSU, and DO = 7.43 mg/L). Metal concentrations increased significantly (p<0.05) in sediments (3.19, 93.92 and 52.83 mg/kg for Fe, Cr and Ni respectively) than in seawater (0.559, 0.035 and 0.039 mg/L for Fe, Cr and Ni, respectively), confirming the role of the sediments as reservoirs of contaminants. The highest values of metal contents were recorded near the mouth of Selouane River for sediments (3.61, 119.17 and 67.00 mg/kg for Fe, Cr and Ni, respectively) and seawater (0.733, 0.043 and 0.040 mg/L for Fe, Cr and Ni, respectively) than New pass. The highest values were recorded near the mouth of the Selouane River, probably due to terrigenous inputs and runoff from the watershed. These results highlight the existence of spatial and seasonal variability in trace metals within the lagoon and underscore the importance of regular environmental monitoring to better understand contamination processes and assess ecological risks in this Mediterranean coastal ecosystem.