The use of aquatic moss (Fontinalis antipyretica) as monitor of contamination in standing and running waters: limits and advantages

The aim of this work is to verify whether water moss (Fontinalis antipyretica) could be used as a monitor of trace element contamination in lotic and lentic waters. The investigation was split up the into three sequential experimental trials. 1) Experiments have been set up in lab in order to evaluate the amount of trace elements (Cd, Pb, Cr, Cu and Hg) released by moss during a period of 133 days, under controlled chemical-physical conditions. A release of 64% of Hg, 83% of Cr and 70% of Pb was found, whereas no re lease of Cd and Cu has been observed. 2) Clean moss has successively treated with running water at different pH and then treaded with Cu, Cr, Hg and Pb, in order to evaluate the dynamics of accumulation of trace elements in moss. Specifically, three basins containing 100 liters of Lake Maggiore water were equipped with three distinct pumps (15 l min-1 each) ensuring the water circulation into a glass tube were arranged. Afterwards, 105 thallus, equivalent to 4.5 g of Fontinalis antipyretica, were fixed into each glass tube. The accumulation dynamics was calculated by collecting moss and water at the beginning, after 1 h, 6 h, 1 day, 4, 9, 14 and 28 days of the experiment. Results showed that the metals accumulation was significant during the first hour. 3) Samples of clean moss were placed in situ. Nine sites in Lake Orta, characterized by high contents of elements due to the anthropic activities, the Toce River and other minor rivers, have been chosen in order to estimate the ability of moss to accumulate Cu, Cr, Pb and Hg from water, and to localize the metal pollution sources. In three sites the Cu average concentration in Fontinalis antipyretica increased from 167 mg kg-1 dry moss to 2100 mg kg-1 after 14 days and to 2900 mg kg-1 after 28 days. A marked accumulation of Hg was observed in Fontinalis antipyretica located in site no 6 (from an initial concentration of 0.2 mg kg-1 dry moss to 17.7 mg kg-1 after 14 days, and 24.6 mg kg-1 after 28 days). The results showed that Fontinalis antipyretica had the ability to accumulate great amounts of trace elements in a short time (a few days and/or a few weeks), whereas the release occurred more slowly (a few months). Therefore, it could be reasonable to stress that moss can be used to monitor water contamination and sources, and to characterize environments with different types of contaminated, such as industrial and urban areas.