Mercury in the Mediterranean. Part 2: processes and mass balance

• Published in: Environmental science and pollution research international 2014-03, Vol.21 (6), p.4081-4094
• Main Authors: Žagar, Dušan, Sirnik, Nataša, Četina, Matjaž, Horvat, Milena, Kotnik, Jože, Ogrinc, Nives, Hedgecock, Ian M, Cinnirella, Sergio, De Simone, Francesco, Gencarelli, Christian N, Pirrone, Nicola
• Format: Article
• Language: English
• Subjects: Air Pollutants - analysis; Animals; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Bioaccumulation; Coasts; Compartments; Contaminants; Deep sea; Deep water; Dimethylmercury; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental Monitoring; Environmental Pollution - statistics & numerical data; Equilibrium; Fish; Fish harvest; Geologic Sediments - chemistry; Gibraltar; Heavy Metals in the Environment : Sources; Information processing; Interactions and Human Health; Marine environment; Marine pollution; Mathematical models; Mediterranean Sea; Mercury; Mercury (metal); Mercury - analysis; Methylmercury; methylmercury compounds; pollutants; Pollution; Pollution studies; seafoods; Sediments; Speciation; Thermocline; Toxic substances; Toxicity; Transformations; Transport; Trends; Upwelling; Waste Water Technology; Water Management; Water Pollutants, Chemical - analysis; Water Pollution Control
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-013-2055-5

Mass balance of contaminants can provide useful information on the processes that influence their concentrations in various environmental compartments. The most important sources, sinks and the equilibrium or non-equilibrium state of the contaminant in individual environmental compartments can also be identified. Using the latest mercury speciation data, the results of numerical models and the results of recent studies on mercury transport and transformation processes in the marine environment, we have re-evaluated the total mercury (HgT) mass balance in the Mediterranean Sea. New calculations have been performed employing three distinct marine layers: the surface layer, the thermocline and the deep sea. New transport mechanisms, deep water formation and density-driven sinking and upwelling, were included in the mass balance calculations. The most recent data have even enabled the calculation of an approximate methylmercury (MeHg) mass balance. HgT is well balanced in the entire Mediterranean, and the discrepancies between inputs and outputs in individual layers do not exceed 20 %. The MeHg balance shows larger discrepancies between gains and losses due to measurement uncertainties and gaps in our knowledge of Hg species transformation processes. Nonetheless, the main sources and sinks of HgT (deposition and evasion) and MeHg (fluxes from sediment, outflow through the Gibraltar Strait) are in accordance with previous studies on mercury in the Mediterranean Basin. Mercury in the Mediterranean fish harvest is the second largest MeHg sink; about 300 kg of this toxic substance is consumed annually with sea food.