Effect of land-cover changes on heavy metals concentration and ecological risk in sediments of Tahaddart estuary, Morocco

Abstract

Long-term trends of trace element contamination in coastal ecosystems are important for assessing the impact of land cover changes on the environment quality. In this study, the assessment of historical land cover changes and contamination status trends of Tahaddart estuary (N-W, Morocco) was investigated. Two sediment cores were selected, analyzed for trace elements (TEs), compared with sediment quality guidelines, and assessed by using environmental and ecological indices. Radiometric dating was performed on sediment core by using ²¹⁰Pb and ¹³⁷Cs isotope. Identification and description of the land cover patterns from 1984 to 2016 was analyzed using GIS methods. The geomatic results showed significant decline in agricultural land, forests, wetlands, and beaches/dunes between1984 and 2016, which are increasingly replaced by artificial land. The radio-dating of sediment core indicate that the mean sedimentation rates are 0.53 cm/years based on ²¹⁰Pb activities. The ecotoxicological risk and contamination indexes revealed a gradual deterioration in the environment quality of Tahaddart with moderate contamination level and 21% risk of toxicity. This research provides a reference database for costal area development.