Heavy metal content and potential ecological risk assessment of sediments from Khnifiss Lagoon National Park (Morocco)

Abstract

Coastal lagoons are important but sensitive environments, being transitional zones between land and sea. The Khnifiss lagoon is the most important desert wetland in Morocco, but little data have been produced concerning heavy metal geochemistry and enrichments in the sediments. Therefore, 26 surface sediments (15 intertidal and 11 subtidal) and 2 sediment cores were collected in 2016 and analyzed for a selection of heavy metals. The data were processed to assess the degree of contamination and the corresponding potential ecological risk, using several accumulation/enrichment indices, and the singular and multi-metal risk indices. Mean concentrations in the bottom layers of the two cores, dating from a pre-industrial age according to geochronological analysis, were used as the local geochemical background. The resulting values were on the whole lower than those reported for other areas of the northeastern coast of Morocco. Multivariate statistics were also applied to better understand relationships among variables (metals and other geochemical parameters) and to reveal similarities among sample groups. The results showed that, although the lagoon is not yet affected by significant anthropogenic influences, small enrichments can be recognized, especially for Ni and Cd. The cause may be related to the proximity to the main national highway, the vehicles and machinery used in the saltworks located in the area, and the small harbors used principally for fishing. In addition, industrial emissions from the Atlantic coast of Morocco and adjacent countries can be reasonably attributed as additional contributors to the enrichments. In terms of potential ecological risk, Cd shows the greatest impact compared to the other metals investigated.

Evaluating coastal lagoon sustainability through the driver-pressure-state-impact-response approach: a study of Khenifiss Lagoon, southern Morocco

“…A study conducted by Tnoumi et al (2022), based on the calculation of the contamination factor (µCF), revealed that intertidal sediments of the lagoon are more sensitive to contamination than subtidal sediments, which is related to the important role of tidal cycles in the transport and deposition of contaminants that originate in the city of Tarfaya, the Canary Islands, and industrial emissions from the Atlantic. However, compared to other Moroccan lagoons (Sidi Moussa, Nador, and Oualidia), the potential ecological risk posed by heavy metals in the KL is classified as low (Tnoumi et al, 2022).…”

Spatial distribution, sources, and risk assessment of heavy metals in sediments from industrial areas in the Kuye River Basin in Shenmu, China

“…Saha explored different types of GIS spatial interpolation methods, and the final results show that the inverse distance weighting method (IDW) is the optimal interpolation model for studying the spatial distribution pattern of toxic metal content (Saha et al, 2022). Sediment quality guidelines (SQG), pollution load index (PLI), and human health risk assessment have been widely applied to metal ion hazard assessment in various regions (Kolawole et al, 2022;Lim et al, 2022;Mor et al, 2022;Tnoumi et al, 2022;Zhang et al, 2022a). Xu studied the Hulan River Basin and found that Cd has caused serious biological risk in estuarine areas.…”

Spatial Distribution of Trace Elements in Sub-Surficial Marine Sediments: New Insights from Bay I of the Mar Piccolo of Taranto (Southern Italy)

“…Sediments are therefore considered the most conservative environmental matrix and represent the final sink of most anthropogenic contaminants, thus playing a primary role both in the accumulation of pollutants through the deposition of suspended particles and adsorption by clay minerals and in their redistribution [3]. Inorganic compounds and trace elements, whose presence in coastal zones can be attributed to both natural processes and anthropogenic activities [4] and reference therein, are characterized by high persistence in the various environmental matrices and can lead to bioaccumulation with consequent negative impacts on ecosystems. The presence of high concentrations of trace metals in the marine sediments represents a global issue since worldwide the coastal areas host the highest density of anthropogenic activities, including industrial systems [metallurgical, steel, chemical, pharmaceutical, petrochemical, mechanical], arsenals, landfills, shipyards, and harbors, with the related high maritime bustle [5][6][7][8][9][10].…”