Relationships between trace elements in Posidonia oceanica shoots and in sediment fractions along Latium coasts (northwestern Mediterranean Sea) (original) (raw)

2016, Environmental Monitoring and Assessment

The Mediterranean endemic seagrass Posidonia oceanica is widely used as a sensitive bioindicator of trace elements (TEs) in the coastal environment. Therefore, a bulk of data exist on TE levels from impacted versus unpolluted sites while only recent studies started comparing TE accumulation in plant compartments versus both water column and sediment characteristics. In this study, six TEs (As, Cd, Cr, Cu, Ni, Pb) were analyzed in P. oceanica shoots related to depth (−10 and −20 m) and to TE concentrations in the different grain size fractions of the sediment, from two Sites of Community interest (SIC) in the central Tyrrhenian Sea. TE concentrations in both shoots and sediment were generally low, except for Cr. Cu was the only element showing significantly different concentrations at the two sites while As differed significantly between samples taken at different depths. TE concentrations in the unsieved sediment were found uncorrelated to TEs in shoots except for the important nutrient Cu (positive correlation). The finest sediment fractions were enriched in TEs and significantly correlated to Cd, Cr, Cu, and Ni concentrations in the shoots. Keywords Trace elements. Sediment grain size fractions. Bioaccumulation. Tyrrhenian Sea Background The environmental quality of coastal habitats of the Mediterranean Sea is seriously challenged by a plethora of anthropogenic impacts resulting from the multiple and conflicting use of coasts, urbanization, industrialization, mining, waste disposal, aquaculture, tourism, or transports (Micheli et al. 2013). One of the consequences of these activities is the chemical contamination by trace elements (TEs), which are both toxic and persistent, hence accumulating in marine living organisms along their life cycle and so entering the food chain (Nixon and Fulweiler 2009). For this reason, trace elements are regarded as dangerous pollutants and some of them such as Cd, Pb, Hg, and Ni are listed as priority substances in the European Environmental Quality Standard Directive (EQSD 2008/105/EC) and subject to control under several directives and regulations. An effective monitoring of trace element concentrations is therefore essential and has required the identification of reliable bioindicators responding to the concentration and bioavailability of elements present in the marine waters and soil (Costanza et al. 1997). Among the