Seasonal and Spatial Patterns of Ecotoxicological Indices of Trace Elements in Superficial Sediments of the Marchica Lagoon Following Restoration Actions during the Last Decade

Abstract

Marchica Lagoon, a Ramsar site on the Mediterranean coast of Morocco, is experiencing the impacts of watershed pollution, which includes pollutants from the domestic, agricultural, industrial, and mining sectors. Restoration actions were undertaken around this lagoon during the last decade in order to protect its ecological value and to develop tourist activity. To conserve the biodiversity in the lagoon, it is important to assess the environmental state of this ecosystem. This study aims to evaluate the ecotoxicological state of sediments through the post restoration characterization of the trace elements Pb, Cu, Zn, Cr, Co, and Ba, as well as their correlation to the major elements, grain size, and total organic carbon, sampled during two campaigns (the wet and dry seasons of 2018) across a sampling network of thirteen stations. Multivariate analysis and ecotoxicological risk assessment of the trace elements using the sediment quality guidelines and five pollution indices (geoaccumulation index (Igeo), enrichment factor (EF), contamination factor (CF), pollution-load index (PLI), and mean effect range median quotient (m-ERM-Q)) revealed contamination of the lagoon by Pb, Zn, and Cu, and minimal pollution by Cr, Co, and Ba. The distribution of the biological-risk index reveals that four zones of the lagoon may present a high probability of toxicity, thus constituting potential risk areas for aquatic organisms: during the wet season, the area in the northwestern sandbar border, the southwest eutrophication zone, and the mouth of the stream valley conveying industrial discharges; and during dry season, the northwestern eutrophication zone. Despite the restoration actions achieved around the lagoon, the lead, zinc, and copper concentrations increased, and their variation was significant between group stations. The biodiversity conservation of Marchica Lagoon requires continuous monitoring and assessment, as well as the implementation of an integrated management plan with restoration actions, not only around the lagoon, but also at its watershed level.

Assessment of old eutrophication in the sediments of Marchica Lagoon (a post-restored lagoon, Mediterranean): The role of geochemistry and granulometry of the sediments

“…In our study, recorded TOC rates were slightly lower than those recorded by Bloundi et al (2008) (up to 7.59%), consistent with those published by Oujidi et al (2021) and higher than the results of Aknaf et al (2022). The high values of TOC are related to hydrodynamic regime, muddy fraction; which is mostly composed of fine clay minerals with a high ability to interact with organic matter, and the strong movement of terrigenous organic matter delivered toward the lagoon, as reported by Ben Mna et al (2021).…”

“…Our results show that total phosphorus concentrations in sediments are higher than those reported by Oujidi et al (2021). Comparing our results with those obtained from other lagoons, TN contents in sediment of the Gulf of Tunis ranged from 0.170 to 1.46 mg/g, with an average of 0.66 mg/g, and TP con-tents ranged from 0.1 to 0.68 mg/g (Ben Mna et al 2021), and in the Bizert Lagoon, phosphorus ranges from 464-619 mg/g 15-20 mmol P/g in surface core sediment (Zaaboub et al 2014).…”

“…The organic index values were interpolated (inverse distance weighting) on the Marchica map to show the seasonal variation of this index along the Marchica Lagoon during the study period. Normality was not verified generally (Shapiro-Wilk test, P > 0.05); statistical analysis was applied using Spearman's coefficient to test significant correlations between the above parameters and the geochemical characteristics and granolumetry of sediments by using data of Oujidi et al (2021). To investigate the relationships between the variables and their possible distribution pattern, a PCA was used.…”

Assessment of the Coastal Marchica Watershed through Ecotoxicological Indices of Trace Elements in Superficial Sediments

“…Granulometry analysis was measured by a laser particle size analyzer (Malvern Mastersizer 2000) and Total organic carbon analysis by a LECO carbon analyzer. Analysis details are given in [8].…”

Geoquímica E Petrografia De Depósitos Quaternários Da Porção Sw Da Praia Brava, Armação Dos Búzios, Rj, Brasil: Edfrx E Difração a Laser

“…Para as análises geoquímicas, cada uma das amostras foi quarteada a fim de se obter porções de 50 g. destinados à análise de Fluorescência de Raios-X com Energia Dispersiva (EDFRX). O EDFRX, (Bruker S1 Turbo SD;NYAMBURA et al, 2013;FLOOD et al, 2017;GOMES et al, 2020;OUJIDI et al, 2021), foi utilizado por um tempo de 120 segundos em uma velocidade de 100.000 contagens por segundo para cada uma das amostras. O equipamento utiliza um ânodo de Ag, que permite a medição de 25 elementos e um detector Silicon Deriva Detector (SDD) de 10 mm 2 com refrigeração termoelétrica e resolução de ~145 eV a MnKα (BAZAES CASANOVA, 2013).…”