Assessing trace metal pollution along the northeast and North Yorkshire coasts using brown algae

Sediments in the Tees Estuary are among the most metal-contaminated in the UK, reflecting a legacy of metal mining and industrial activity. Regular dredging and offshore disposal of these sediments may contribute to marine metal pollution, yet few studies have investigated bioavailable concentrations in this region. This study employed four species of brown algae (Laminaria digitata, L. hyperborea, Fucus vesiculosus, and F. serratus) as biological monitors to assess trace metal pollution along the northeast and North Yorkshire coastlines. Samples underwent acid digestion and were analysed for Fe, Zn, Mn, Cu, Ni, Cd, Cr, and Pb using inductively coupled plasma mass spectrometry (ICP-MS).

Overall, trace metal concentrations were comparable to background levels, indicating largely unpolluted conditions and minimal change since the late 1990s. Nevertheless, significant declines in macroalgal Fe, Cu, Zn, and Pb levels downstream of the Tees Estuary point to sediment disturbance as a potential source of contamination. Anomalously elevated Pb concentrations exhibited by two specimens from South Gare suggest transient inputs or fine particulate contamination of sample surfaces. Some trace metal concentrations at Cullercoats Beach were also relatively high compared to other sites, indicating possible influence from the Tyne Estuary. Interspecific and intrathallus variations were evident for several elements, with factors such as shore level, season, and year also likely affecting metal uptake. Despite these complexities, brown algae proved to be effective indicators of bioavailable trace metals, though their continued application requires tighter control of sampling variables and an improved understanding of uptake processes.