Mattia Cesa

Moss bags as indicators of trace element contamination in Pre-alpine streams

Abstract Moss bags of the aquatic bryophyte Rhynchostegium riparioides (Hedw.) C.E.O. Jensen (=Platyhypnidium riparioides (Hedw.) Dixon) were transplanted into freshwaters of the Province of Belluno (NE Italy). This study was aimed at testing the bioaccumulation of trace elements in Pre-alpine Dolomitic streams, where this species does not grow naturally, and where analyses of water samples have never revealed trace element pollution. Mosses were collected after 13, 26 and 59 days of exposure. The concentrations of nine trace elements in the apical shoots were measured. Average concentrations reached in three control stations were adopted as background values, to calculate the contamination factor (CF). Transplants accumulated trace elements and discriminated between non- or scarcely contaminated waters (low CF) and polluted ones (high CF). Furthermore, two patterns of contamination were revealed by multivariate analysis: (I) metals (Cr, Cu, Ni) from galvanic industries, and (II) metals (Pb, Zn) from other industrial/domestic sources or mine sites.

A factor influence study of trace element bioaccumulation in moss bags.

Moss bags of Rhynchostegium riparioides were exposed to different water concentrations of 11 trace elements under laboratory conditions, according to a saturated fractional factorial design (67 treated combinations), with the aim of measuring (1) element uptake and (2) the main effects and first-order interactions of influent factors. Bioaccumulation was directly proportional to water concentration, but the uptake ratio (ranging from 102 to 105) also depended on the concentration of other metals. The highest uptake ratios were observed for Al, Cu, Cr, Hg, and Pb. The multiple regression model showed that interactions among elements exist and induce both antagonism (Fe is the most frequent competitor) and synergism (Cr exerts a great influence on Pb and Zn uptake). Interactions might be relatively strong (as for As, Cr, and Pb) or weak (Cd and Hg). This evidence should be taken into consideration in biomonitoring surveys of industrial sites, where effluents release more than one contaminant.

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 <or=4 microg Hg(2+)L(-1), while a saturation curve was observed at higher concentrations. Uptake followed a 3-stage trend for increasing exposure times: a phase of rapid accumulation (4-5d), followed by an equilibrium plateau (2-3d) and then by a second accumulation phase. The factor influence study revealed that variations in pH or water concentration of alkaline metals, within the range of typical values in freshwaters of NE Italy, did not produce significant differences (p>0.05) in the Hg uptake ratio (0.496x10(5)<or= Bio Accumulation Factor <or= 1.73x10(5)). From a database of 28 Hg concentrations in mosses exposed to 0.25-4 microg Hg(2+)L(-1) for 24-114 h, a mathematical equation was produced, to assess Hg micro-contamination in water. The difference between predicted and real concentration was generally included in the range+/-50%.

Monitoring of aquatic mosses and sediments: a case study in contaminated rivers, Bulgaria

Aquatic mosses and sediments were monitored along Topolnitsa River Basin (Bulgaria), copper-producing and mining region. Six mosses were applied as biomonitors: Bryum turbinatum, Fontinalis antipyretica, Leptodictyum riparium, Platyhypnidium riparioides, Rhizomnium punctatum and Sciuro-hypnum plumosum. Background levels were determined for both plants and fine fraction of sediments collected from an unpolluted site. Contamination factors (CFs) and metal pollution index at each site were presented. The highest sediment enrichment with toxic elements was found in Zlatishka River. Strong increase above background levels showed all 13 heavy metals and toxic elements in biomonitors from stations at Zlatishka and Pirdopska rivers. The two moss species adopted as biomonitors for the first time – Bryum turbinatum and Rhizomnium punctatum – showed high CFs for several heavy metals and contributed to chemical pollution pattern assessment. The parallel use of mosses and sediments in the monitoring study, as well as the applied statistical tools, led to the conclusion that mosses as higher plants revealed pollution patterns not detected by sediments. Results also showed that in a seriously contaminated aquatic environment, which requires rapid assessment, different moss species can be applied for water-monitoring purposes to present preliminary picture of pollution patterns and to direct further studies.

Oven-dried mosses as tools for trace element detection in polluted waters: A preliminary study under laboratory conditions

Abstract The concentration of 11 trace elements, plus Ca, Mg, Na and K was measured in moss bags of living and dead (oven-dried at 105°C) Platyhypnidium riparioides after a 1-week exposure to tap water, and to 0.21, 1.0, 2.5 and 4.0 μM solutions under laboratory conditions, with the aim of (1) observing the accumulation curves and (2) performing a statistical comparison in element concentrations. Uptake occurred both in living and in dead mosses following similar patterns in the two materials: a linear uptake was observed for Cd and Ni, a saturation curve for As, Cu, Hg and Pb, an unclear trend for Al and Mn and a trend leading to a maximum for Cr and Fe. An evident efflux of K indicated alterations in cell membrane permeability in living mosses and cellular damage in dead mosses. Living mosses accumulated higher concentrations of Cr (+4/+49%) and Mn (+124/+216%), while dead mosses accumulated higher concentrations of Cd (+13/+50%), Cu (+26/+51%), Ni (+22/+139%) and Zn (+22/+63%). Dead mosses maintained a considerable uptake efficiency for several trace elements, and sometimes even increased it as compared with living mosses, thus proving to be suitable for standard kits.