The Importance of Organic Matter in Controlling the Metal Variability and Mobility in Seagrass Sediments

Abstract

Metal contamination in seagrass beds has been extensively studied in the past decades. Most of earlier studies have focused on reporting metal concentration in different compartments of seagrass ecosystem, with little attention given to the role of sediment organic matter in controlling the metal mobility and bioavailability. This study investigated that metal contamination (cobalt, nickel, copper, arsenic, chromium, silver, cadmium, and antimony) in seagrass sediments in Hainan Island, China and illustrates how various geochemical factors impact the spatial variability of the metal concentrations. Particularly, we explored how organic matter influence metal storage and mobility in the seagrass sediments. The enrichment of metals in these sediments was not only associated with levels of organic matter but also their sources. The organic matter content showed positive correlations with both metal concentrations and acid-extractable fractions of chromium, silver, and cadmium, highlighting its significant role in influencing metal accumulation and mobility in sediments. Overall, this research enhances our understanding of metal cycling within seagrass ecosystems and highlights the vital role of seagrass-derived organic matter in regulating metal dynamics.

Keywords: Seagrass, heavy metals, Organic matter, Partial extraction, Biomonitoring