Sorption of cadmium and zinc in selected species of epigeic mosses

The significance of heterophasic ion exchange in active biomonitoring of heavy metal pollution of surface waters

We have carried out studies to examine the possibility of using biosorbents: the epigeic mosses Pleurozium schreberi (Willd. ex Brid.) Mitt., and the epiphytic lichens Hypogymnia physodes (L.) Nyl. in active biomonitoring of heavy metal pollution of surface waters. The dried sea algae Palmaria palmata (L.) Weber & Mohr were used as the third biosorbent. The studies were conducted in the waters of the Turawa Reservoir, a dam reservoir with a significant level of eutrophication in south-western Poland. Incremental concentrations of Mn, Ni, Zn, Cu, Cd, and Pb were determined in the exposed samples. It was shown that a 2-h exposure period increases the concentration of some metals in the exposed samples, even by as much as several hundred percent. High increments of nickel concentrations in the algae Palmaria palmata (mean: 0.0040 mg/g, with the initial concentration of c0 < 0.0016 in the algae) were noted, with negligible increments in concentrations of this metal in mosses and lichens. In contrast, mosses and lichens accumulated relatively high amounts of Cd (mean: 0.0033 mg/g, c0 = 0.00043 mg/g) and Pb (mean: 0.0243 mg/g, c0 = 0.0103 mg/g), respectively.

Bioaccumulation of Trace Elements from Aqueous Solutions by Selected Terrestrial Moss Species

The interrelationship between metal concentrations in mosses and their surroundings prompts research toward examining their accumulation properties, as it is particularly important for their usage in biomonitoring studies that use mosses. In this study, the kinetics of elemental sorption in three moss species (Pleurozium schreberi, Dicranum polysetum, and Sphagnum fallax) were investigated under laboratory conditions. Sorption from metal salt solutions was carried out under static conditions with decreasing elemental concentration. Functional groups responsible for binding metal cations to the internal structures of the mosses were also identified. It was shown that the equilibrium state was reached after about 60 min. Under the conditions of the experiment, in the first 10 min of the process, about 70.4-95.3% of metal ions were sorbed from the solution into the moss gametophytes by P. schreberi (57.1-89.0% by D. polysetum and 54.1-84.5% by S. fallax) with respect to the concentration of this analyte accumulated in the mosses at equilibrium. It can be assumed that the exposure of mosses with little contamination by heavy metals in an urbanized area under active biomonitoring will cause an increase in the concentration of these analytes in proportion to their concentration in atmospheric aerosols. In the case of P. schreberi and D. polysetum, the O-H/N-H band was enormously affected by the adsorption process. On the other hand, FTIR (Fourier transform infrared spectroscopy) analysis of S. fallax after adsorption showed slight changes for most of the bands analyzed. Based on this study, it can be concluded that mosses can be used as, for example, a biomonitor in monitoring of urban ecosystems, but also in the phytoremediation of surface waters.

Is Your Moss Alive during Active Biomonitoring Study?

Biomonitoring was proposed to assess the condition of living organisms or entire ecosystems with the use of bioindicators-species sensitive to specific pollutants. It is important that the bioindicator species remains alive for as long as possible while retaining the ability to react to the negative effects of pollution (elimination/neutralization of hazardous contaminants). The purpose of the study was to assess the survival of Pleurozium schreberi moss during exposure (moss-bag technique) based on the measurement of the concentration of elements (Ni, Cu, Zn, Cd, and Pb), chlorophyll content, and its fluorescence. The study was carried out using a CCM-300 portable chlorophyll content meter, portable fluorometer, UV-Vis spectrophotometer, and a flame atomic absorption spectrometer. As a result of the laboratory tests, no significant differences were found in the chlorophyll content in the gametophytes of mosses tested immediately after collection from the forest, compared to those drying at room temperature in the laboratory (p = 0.175 for Student's t-test results). Mosses exposed using the moss-bag technique of active biomonitoring were characterized by a drop in the chlorophyll content over 12 weeks (more than 50% and 60% for chlorophyll-a and chlorophyll-b, respectively). Chlorophyll content in mosses during exposure was correlated with actual photochemical efficiency (yield) of photosystem II (calculated value of Pearson's linear correlation coefficient was 0.94-there was a significant correlation between chlorophyll a and yield p = 0.02). The highest metal increases in mosses (RAF values) were observed for zinc, lead, and copper after the second and third month of exposure. The article demonstrates that the moss exposed in an urbanized area for a period of three months maintains the properties of good bioindicator of environmental quality.

Towards rare earth element recovery from wastewaters: biosorption using phototrophic organisms

Abstract

Whilst the biosorption of metal ions by phototrophic (micro)organisms has been demonstrated in earlier and more recent research, the isolation of rare earth elements (REEs) from highly dilute aqueous solutions with this type of biomass remains largely unexplored. Therefore, the selective binding abilities of two microalgae (Calothrix brevissima, Chlorella kessleri) and one moss (Physcomitrella patens) were examined using Neodym and Europium as examples. The biomass of P. patens showed the highest sorption capacities for both REEs (Nd³⁺: 0.74 ± 0.05 mmol*g⁻¹; Eu³⁺: 0.48 ± 0.05 mmol*g⁻¹). A comparison with the sorption of precious metals (Au³⁺, Pt⁴⁺) and typical metal ions contained in wastewaters (Pb²⁺, Fe²⁺, Cu²⁺, Ni²⁺), which might compete for binding sites, revealed that the sorption capacities for Au³⁺ (1.59 ± 0.07 mmol*g⁻¹) and Pb²⁺ (0.83 ± 0.02 mmol*g⁻¹) are even higher. Although different patterns of maximum sorption capacities for the tested metal ions were observed for the microalgae, they too showed the highest affinities for Au³⁺, Pb²⁺, and Nd³⁺. Nd-sorption experiments in the pH range from 1 to 6 and the recorded adsorption isotherms for this element showed that the biomass of P. patens has favourable properties as biosorbent compared to the microalgae investigated here. Whilst the cultivation mode did not influence the sorption capacities for the target elements of the two algal species, it had a great impact on the properties of the moss. Thus, further studies are necessary to develop effective biosorption processes for the recovery of REEs from alternative and so far unexploited sources.

Key points

• The highest binding capacity for selected REEs was registered for P. patens.

• The highest biosorption was found for Au and the biomass of the examined moss.

• Biosorption capacities of P. patens seem to depend on the cultivation mode.

Trace elements in Polytrichum commune and Polytrichastrum formosum from the Karkonosze Mountains (SW Poland)

The Karkonosze National Park, an unique mountainous biosphere reserve, is influenced by long-distance anthropogenic atmospheric transport of among others trace elements and additionally by local tourist centres, which may be supplementary sources of pollution. Discharged trace elements are non-degradable, and their level must be precisely monitored. Therefore, the concentrations of As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Rb and Zn in Polytrichum commune and Polytrichastrum formosum collected from the Karkonosze sites influenced only by long-range pollution and from sites in the vicinity of local tourist centres were established. P. commune and P. formosum revealed the ability to accumulate higher concentrations of trace elements while growing in locally contaminated sites in comparison with sites free from such pollution. Therefore, both species may be utilised for bioindication in the Karkonosze National Park. Elevated levels of trace elements in both species (except for Hg) in comparison with concentrations typical for mosses from unpolluted sites point to the existence of pollution of this area. P. commune was a better bioindicator of Cd, Co, Cr, Cu, Mo, Ni, Pb and Rb than P. formosum, probably because of the larger gametophytes and its morphology, which appears prone to an increased uptake of trace elements from the atmosphere.

Metals in Pleurozium schreberi and Polytrichum commune from areas with various levels of pollution

Metals deposited into ecosystems are non-degradable and become one of the major toxic agents which accumulate in habitats. Thus, their concentration requires precise monitoring. To evaluate pollution around a chlor-alkali plant, a glass smelter, two power plants and a ceramic and porcelain factory, we selected terrestrial mosses with different life forms: the orthotropic and endohydric Polytrichum commune and plagiotropic and ectohydric Pleurozium schreberi. Metal concentrations were determined in both species growing together at sites situated at various distances approximately 0.75, 1.5, 3 and 6 km from polluters. MARS analysis evaluated different tendencies of both species for Cd, Co and Pb accumulation depending on the distance from the emitter. In P. schreberi, the concentration of these metals diminished relatively rapidly with an increasing distance from the emitter up to 3000 m and then stabilised. For P. commune, a steady decrease could be observed with increasing the distance up to 6000 m. PCCA ordination explained that both species from the vicinity of the chlor-alkali plant were correlated with the highest Co, Cr, Cu, Fe and Pb as well as Mn and Ni concentrations in their tissues. The mosses from sites closest to both power plants were correlated with the highest Cd and Zn concentrations. P. commune contained significantly higher Cd, Cr, Ni, Pb and Zn concentrations compared to P. schreberi. This may be caused by the lamellae found in the leaves of P. commune which increase the surface area of the possible aerial absorption of contaminants. Soil may also be an additional source of metals, and it affects the uptake in endohydric P. commune more than in ectohydric P. schreberi. However, the precise explanation of these relations needs further investigation.

Correlating concentrations of heavy metals in atmospheric deposition with respective accumulation in moss and natural surface soil for ecological land classes in Norway between 1990 and 2010

This study investigated whether statistical correlation of modeled atmospheric heavy metal deposition and respective accumulation in moss and natural surface soil varies across natural landscapes in Norway. Target metals were cadmium, lead, and mercury, and analyses were run between 1990 and 2010 on a 5-year interval. The landscape information was derived from the Ecological Land Classification of Europe. Correlations between concentration and respective deposition data were computed for each land class. The strongest correlations between heavy metal concentrations in atmospheric deposition and corresponding levels in moss and natural surface soil were observed for lead. Correlations for mercury were weaker compared to those calculated for cadmium and lead, indicating that atmospheric transport of mercury occurs at a larger spatial scale, while accumulation additionally seems to be influenced by factors operating on smaller scales. The correlation between concentrations in atmospheric deposition and moss is landscape-specific and metal-specific. The same holds true for the relations between heavy metal concentration in modeled atmospheric deposition and natural surface soil. The results of this investigation are in line with similar calculations from across Europe. They further confirm previous studies indicating that for Norway atmospheric transport is a main source of lead and cadmium accumulation in moss as well as in natural surface soil.