“…It should be noted, however, that 137 Cs did not disappear in the layers older than 1954, and this is a feature related to the fraction of 137 Cs that is diffuse in interstitial water (Abril et al, 1991 ). The CRS model also allowed MAR to be estimated for each layer: in this core, MAR was higher in layers younger than 1968 (mean value = 1.2 ± 0.4 g/(cm 2 year) compared with 0.5 ± 0.2 g/(cm 2 year) in the older layers), comparable with values in other lagoons in Morocco (Benmhammed et al, 2021 ; Maanan et al, 2013 , 2014 ). Fig.…”
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.
“…It should be noted, however, that 137 Cs did not disappear in the layers older than 1954, and this is a feature related to the fraction of 137 Cs that is diffuse in interstitial water (Abril et al, 1991 ). The CRS model also allowed MAR to be estimated for each layer: in this core, MAR was higher in layers younger than 1968 (mean value = 1.2 ± 0.4 g/(cm 2 year) compared with 0.5 ± 0.2 g/(cm 2 year) in the older layers), comparable with values in other lagoons in Morocco (Benmhammed et al, 2021 ; Maanan et al, 2013 , 2014 ). Fig.…”
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.
“…Several authors [11][12][13]33,34] have assessed the impact of metals on the toxicity of aquatic organisms using sediment quality guidelines (SQGs). The threshold effect level (TEL) and probable effect level (PEL) were used in this study to assess the potential biotic influence of metals contained in sediment samples.…”
Section: Geo-accumulation Index (Igeo)mentioning
confidence: 99%
“…The growth of human activities around coastal cities, mainly industrial activities in response to the development of socioeconomic sectors, has resulted in human overpopulation and pollution level increase, affecting water resources, sediment, and marine organisms [8,11,21,22]. Indeed, coastal sediments have been found to be polluted by wastewater effluent issued from domestic and industrial activities [17,[22][23][24], where several studies indicated that coastal sediment is an important tool for analyzing pollution levels by heavy metals [11,17,22,[25][26][27][28][29][30][31][32][33][34]. According to statistical analysis, about 85% of heavy metals are accumulated in superficial sediments [11,22,35,36].…”
This study assesses the spatial distribution and contamination level of heavy metals in Safi Bay surface sediments. In this order, 28 surface sediment samples were retrieved from the study area and analyzed using the x-fluorescence method. To assess the contamination of the examined sediment, we used geo-ecological indices such as contamination factor (CF), degree of contamination (DC), geo accumulation index, and pollution load index (PLI). The results show that only Pb and Cd present moderate and considerable contamination in some sampling sites, while other elements (Cr, Cu, Zn, and Ni) indicate no contamination and low contamination by these elements. The inhomogeneous distribution of metal concentrations along the bay suggests different heavy metal sources. Given the ecological and socioeconomic importance of the study area, there is a need for a further analysis of both sediments and biological samples for a better understanding of the contamination levels and origin of metals, in addition to the sustainability of Safi Bay.
“…The two cores were previously dated by using lead-210 and cesium-137 as chronometer and time-marker respectively, to obtain the age-depth relationships. The Constant Rate of Supply (CRS) dating model was applied for this purpose and the results were published in a separate paper [12]. The vertical profiles of REEs+Y versus CRS ages are plotted in Figure 2, in which the historical input of these trace elements to Sidi Moussa lagoon can be appreciated.…”
Section: Vertical Distribution Of Rare Earth Elements + Yttriummentioning
Rare Earth Elements and yttrium (REEs+Y) were measured by inductively Coupled Plasmas -Mass Spectrometry in two previously dated sediment cores collected from Sidi Moussa lagoon, located in the Moroccan Atlantic coast, in order to establish the historical inputs of these elements and to determine the contribution of anthropogenic activities. In an attempt to clarify the phase associations of REE+Y, the Ce anomaly profiles were partitioned into three parts: the upper part with negative anomalies, except for a positive Ce/Ce* peak in 1983, the middle part with positive anomalies rising to high Ce/Ce*, and the lower part with also fairly increasing positive anomalies. Pearson correlations were calculated between REE+Y and major elements (Mn, Fe and Al) in different parts of Core-1. REE+Ys, except for Pr, were significantly correlated only with Mn, which suggests that the associated phase in the upper part consists of Mn oxides. The central part is characterized by a negative correlation of REE+Y with Mn and a positive correlation with Fe. The maximal concentrations were observed in two horizons in the sediment cores being attributed to both natural and industrial sources. The association of REEs with manganese oxides, iron-rich minerals and detritus material was changing in different parts of the cores. Only in specific layers, all REEs were weakly to moderately enriched, while yttrium was moderately to strongly enriched. The notable reduction in the upper layers is a reflection of the environmental management plan implemented by the phosphate company and the change in the morphology of the lagoon, which has reduced communication with the ocean.
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