Development of a standard protocol for monitoring trace elements in continental waters with moss bags: inter- and intraspecific differences.

This paper is a contribution for validating a standard method for trace element monitoring based on transplants and analysis of aquatic bryophytes, in the framework of the EC Directive 2000/60. It presents the results of an experiment carried out to assess significant differences in the amount and variability of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in three moss species (Cinclidotus aquaticus, Fontinalis antipyretica, Platyhypnidium riparioides) and two different parts of the moss (whole plant vs apical tips). Mosses were caged in bags made of a plastic net and transplanted for 2 weeks to an irrigation canal impacted by a waste water treatment plant. Trace element concentrations were measured by inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) before and after exposure to the experimental and control sites in five samples. Enrichment factors >>2 were found for Cu, Ni, Mn, Pb and Zn in all moss species, lower in C. aquaticus, intermediate in F. antipyretica and higher in P. riparioides (the species we recommend to use). The analysis of apical tips after exposure instead of the whole plant led to (I) lower concentrations of As, Co, Cr, Fe and Zn in C. aquaticus (-7 to -30%) and of Fe and Pb (-13, -18%) in P. riparioides, (II) higher concentrations of Cu, Ni and Zn (+14 to +18%) in P. riparioides, while (III) no significant difference (p > 0.05) in F. antipyretica. Data variability after exposure was generally lower in apical tips, especially in C. aquaticus and in F. antipyretica, less in P. riparioides. In the aim of standardizing the moss-bag technique, the analysis of apical tips is recommended.

Moss bags as sentinels for human safety in mercury-polluted groundwaters.

An equation to estimate Hg concentrations of <4 µg/L in groundwaters of a polluted area in NE Italy was set out by using transplants of the aquatic moss Rhynchostegium riparioides as trace element bioaccumulators. The equation is derived from a previous mathematical model which was implemented under laboratory conditions. The work aimed at (1) checking the compliance of the uptake kinetics with the model, (2) improving/adapting the model for groundwater monitoring, (3) comparing the performances of two populations of moss collected from different sites, and (4) assessing the environmental impact of Hg contamination on a small river. The main factors affecting Hg uptake in the field were-as expected-water concentration and time of exposure, even though the uptake kinetics in the field were slightly different from those which were previously observed in the lab, since the redox environmental conditions influence the solubility of cationic Fe, which is a negative competitor of Hg(2+). The equation was improved by including the variable 'dissolved oxygen concentration'. A numerical parameter depending on the moss collection site was also provided, since the differences in uptake efficiency were observed between the two populations tested. Predicted Hg concentrations well fitted the values measured in situ (approximately ±50%), while a notable underestimation was observed when the equation was used to predict Hg concentration in a neighbouring river (-96%), probably due to the organic pollution which hampers metal uptake by mosses.

Implementation of an active 'bryomonitoring' network for chemical status and temporal trend assessment under the Water Framework Directive in the Chiampo Valley's tannery district (NE Italy).

An innovative network based on transplanted bryophytes providing a continuous monitoring of the priority substances Cd, Hg, Ni, and Pb and other trace elements (Co, Cr, Cu, Fe, Mn, Zn) was designed for the watercourses flowing across an industrial district of NE Italy where both permitted and illegal wastes cause sporadic, intermittent or chronic events of environmental alteration. During a two-year preliminary survey, over 300 biomonitoring actions ('moss bag' transplantation and recovery) were successfully carried out at 25 stations: 190 of them occurred under acceptable conditions and provided results suitable for comparisons. Five environmental priorities were assessed and characterized in space and time. For these situations local authorities drafted a protocol for data management, to plan official controls and dissuasive actions. The 'moss bag' technique allows a flexible approach for both surveillance monitoring (trend assessment) and investigations (point source detection) in compliance with the Water Framework Directive 2000/60/EC as suggested by the recent Guidance Document on chemical monitoring of sediment and biota.

S.TR.E.A.M., system for trace element assessment with mosses. An equation to estimate mercury concentration in freshwaters.

Hundred experiments of Hg bioaccumulation with the aquatic moss Rhynchostegium riparioides (Hedw.) C.E.O. Jensen transplanted under laboratory conditions were carried out with the aim of (1) measuring the metal uptake at increasing water concentrations (0.25-128 microg Hg(2+)L(-1)) and increasing exposure time (24-189 h), (2) studying the influence of pH (6.3-8.5) and water concentration of Na (3-114 mg L(-1)), Ca (62-125 mg L(-1)) and Mg (13-54 mg L(-1)) on the metal uptake, (3) achieving a database for mathematical and statistical elaborations, and, (4) producing an equation modelling the uptake. A linear uptake was observed for water concentrations 0.05) in the Hg uptake ratio (0.496x10(5)