Metal Concentrations In Mosses Research Articles

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.

Doğu Karadeniz Bölgesi Sahil Otoyol Çevresindeki Karayosunlarında Trafik Kaynaklı Ağır Metal Analizleri

Bu çalışmanın amacı; Giresun-Samsun otoyol çevresindeki karayosunları kullanılarak Trafik kaynaklı ağır metal kirliliğini belirleyebilmektir. Karayosunları, ağır metalleri biriktirebilme yeteneğinden dolayı, ağır metal hava kirliliğinin belirlenmesinde oldukça uygun biyoindikatörlerdir. Türkiye’nin Doğu Karadeniz bölgesinde yer alan Giresun-Samsun otoyolu çevresindeki karayosunlarının ağır metal analizleri InductivelyCoupledPlasma–MassSpectrometer (ICP-MS) cihazı kullanılarak belirlendi. Karayosunlarının kalitatif analizleri neticesinde Cr, Fe, Mn, V, Zn, Cu, Ni, Pb ve Co olduğu belirlendi. Şehir merkezlerinden toplanan karayosunlarındaki konsantrasyon değerleri sırasıyla 15.12, 6087.31, 301.12, 27.80, 74.20, 38.48, 56.69, 19.40 ve 9.10, mg/kg olarak belirlenirken, şehirler arasından toplanan karayosunlarının ağır metal konsantrasyonları ise 15.56, 4751.23, 247.93, 28.03, 83.71, 33.72, 48.38, 17.20 ve 6,97 kg/kg olarak belirlendi. Genelde karayosunlarında, Krom(Cr), Demir(Fe), Mangan(Mn), Vanadyum(V), Çinko(Zn), Bakır(Cu), Nikel(Ni), Kurşun(Pb) ve Kobalt(Co)’ınkonsantrasyonlarının 2006 ve 2017 yılları arasında azaldığı görüldü. Fakat bu azalmaya rağmen karayosunlarındaki ağır metal konsantrasyonları hala yüksektir.

Comparison of Exposure Techniques and Vitality Assessment of Mosses in Active Biomonitoring for Their Suitability in Assessing Heavy Metal Pollution in Atmospheric Aerosol.

The most widespread and used technique is the moss-bag method in active biomonitoring of air pollution using mosses. In the literature, we can find various studies on the standardization of this method, including attempts to standardize treatments and preparation procedures for their universal application. Few works comprehensively focus on other methods or compare other techniques used in active biomonitoring with mosses, especially including measurements of their vital parameters. Our experiment aimed to assess air pollution by selected heavy metals (Cu, Zn, Cd, Pb, Mn, Fe, and Hg) using three moss species (Pleurozium schreberi, Sphagnum fallax, and Dicranum polysetum) during a 12-week exposure in an urban area. Mosses were exposed simultaneously using four techniques: moss bag in three variants (exposed to air for total deposition of heavy metals, exposed to air for only dry deposition, and sheltered from the wind) and transplants in boxes. Increases in heavy metal concentrations in mosses were determined using the relative accumulation factor (RAF). The actual quantum yield of photosystem II photochemical was also analyzed as the main vitality parameter. The results indicate that all moss species during the changing environmental conditions survived and retained their vitality, although it decreased by >50% during the exposure. The best biomonitor was the moss P. schreberi, whose RAF increments were the highest throughout the study period for the majority of elements. The moss-bag technique had a statistically significant effect (almost 40%) on the concentration value of a given metal for a certain species, and thus it is the most recommended technique that can be applied in air quality monitoring in urban areas. Environ Toxicol Chem 2022;41:1429-1438. © 2022 SETAC.

The influence of environmental conditions on the lifespan of mosses under long-term active biomonitoring

Biomonitoring with living organisms is most often used in order to gather quick information about environmental quality – for example the level of heavy metals polluting the air. Experiments are not often performed when the bioindicator is exposed to pollutants over the long time (6 months and more) because this period required to obtain credible results and the risk not yet studied of physiological changes and of degeneration of the living material which would undoubtedly affect the biomonitoring results. The aim of study was to evaluate the physiological condition of Pleurozium schreberi moss species subjected to continuous exposure for a year, using the moss-bag method, under variable environmental conditions, including atmospheric aerosol contaminated by selected analytes: Cu, Zn, Cd, Hg, Pb determined by flame atomic absorption spectrometer. AMA apparatus was used to measure mercury. The survival of the moss during exposure was assessed based on the measurement of chlorophyll content. As a result of the research, it was found that the concentrations of metals in mosses increased depending on the exposure time and the certain element. It was also found that mosses, despite the long period of exposure to environmental factors and the decreasing content of chlorophyll, still revealed the features of a living organism during the study and can be used in long-term biomonitoring of the environment. It was also proposed to correct the period and duration of P. schreberi exposure to air pollution in relation to the previous literature and recommend the period of 3–6 months.

Long-term exposure to atmospheric metals assessed by mosses and mortality in France

BackgroundLong-term exposure to air pollution affects health, but little is known about exposure to atmospheric metals. Estimating exposure to atmospheric metals across large spatial areas remains challenging. Metal concentrations in mosses could constitute a useful proxy. Here, we linked moss biomonitoring and epidemiological data to investigate the associations between long-term exposure to metals and mortality. MethodsWe modelled and mapped 13 atmospheric metals from a 20-year national moss biomonitoring program to derive exposure estimates across France. In the population-based Gazel cohort, we included 11,382 participants from low to intermediate population density areas and assigned modelled metals to their residential addresses. We distinguished between airborne metals that are primarily of natural origin and those primarily of anthropogenic origin. Associations were estimated between exposure to metals and mortality (natural-cause, cardiovascular and respiratory), using Cox models, with confounder adjustment at individual level. FindingsBetween 1996 and 2017, there were 1313 deaths in the cohort (including 181 cardiovascular and 33 respiratory). Exposure to the anthropogenic metals was associated with an increased risk of natural-cause mortality (hazard ratio of 1.16 [1.08–1.24] per interquartile range of exposure), while metals from natural sources were not. InterpretationSome atmospheric anthropogenic metals may be associated with excess mortality – even in areas with relatively low levels of exposure to air pollution. Consistent with the previous literature, our findings support the use of moss biomonitoring as a tool to assess health effects of air pollution exposure at individual level.

Railroad derived nitrogen and heavy metal pollution does not affect nitrogen fixation associated with mosses and lichens at a tundra site in Northern Sweden

Traffic derived nitrogen (N) and heavy metal pollution is a well-known phenomenon, but little explored in otherwise pristine ecosystems such as subarctic tundra. Here, the main source of N input to the ecosystem is via N2 fixation by moss- and lichen-associated bacteria. While inhibitory effects of N deposition on moss-associated N2 fixation have been reported, we still lack understanding of the effects of traffic derived N and heavy metal deposition on this ecosystem function in an otherwise pristine setting. To test this, we established a distance gradient (0–1280 m) away from a metal pollution source -a railway transporting iron ore that passes through a subarctic birch forest. We assessed the effects of railway-derived pollution on N2 fixation associated with two moss species Pleurozium schreberi, Hylocomium splendens and with the lichen Peltigera aphthosa. Deposition and availability of N and heavy metals (Fe, Cu, Zn, Pb) as well as the respective contents in moss, lichen and soil was assessed. While we found a steep gradient in metal concentration in moss, lichen and soil with distance away from the pollution source, N deposition did not change, and with that, we could not detect a distance gradient in moss- or lichen-associated N2 fixation. Hence, our results indicate that N2 fixing bacteria are either not inhibited by heavy metal deposition, or that they are protected within the moss carpet and lichen tissue.

Comparison of Wet and Microwave Sample Digestion Method for the FAAS and GFAAS Determination of Heavy Metal Concentrations in Moss and Lichen Samples

Comparison of Wet and Microwave Sample Digestion Method for the FAAS and GFAAS Determination of Heavy Metal Concentrations in Moss and Lichen Samples

Assessing temporal trends of trace metal concentrations in mosses over France between 1996 and 2011: A flexible and robust method to account for heterogeneous sampling strategies

Air quality biomonitoring has been successfully assessed using mosses for decades in Europe, particularly regarding heavy metals (HM). Assessing robust temporal variations of HM concentrations in mosses requires to better understand to what extent they are affected by the sampling protocol and the moss species. This study used the concentrations of 14 elements measured during four surveys over 15 years in France. Analyses of variance (ANOVA) and a modeling approach were used to decipher temporal variations for each element and adjust them with parameters known to affect concentrations. ANOVA followed by post hoc analyses did not allow to estimate clear trends. A generalized additive mixed modeling approach including the sampling period, the collector and the moss species, plus quadratic effects, was used to analyze temporal variations on repeated sampling sites. This approach highlighted the importance of accounting for non-linear temporal variations in HM, and adjusting for confounding factors such as moss species, species-specific differences between sampling periods, collector and methodological differences in sampling campaigns. For instance, lead concentrations in mosses decreased between 1996 and 2011 following quadratic functions, with faster declines for the most contaminated sites in 1996. On the other hand, other HM showed double trends with U-shaped or hill-shaped curves. The effect of the moss was complex to handle and our results advocate for using one moss species by repeated site to better analyze temporal variations.

Monitoring Airborne Heavy Metal Using Mosses in the City of Xuzhou, China.

The concentrations of six elements (Cd, Cr, Cu, Ni, Pb and Zn) were measured in moss (Haplocladium microphyllum) samples collected from 55 urban sites in the summer of 2013. The objectives were to evaluate variations in the heavy metal concentrations in mosses across Xuzhou, and to develop maps of metal pollution for this region. Despite great variations in the concentrations of the six heavy metals in the mosses, significant correlations among certain heavy metals were identified, suggesting that these pollutants likely originated from identical sources. With the exception of Cr, there was no significant correlation in metal concentration between the moss tissues and adhering soils. The highest concentration of Cr occurred in the west. However, the spatial distribution for the other metals generally showed higher concentrations in the northeast, likely due to greater contamination by industrial activities and higher traffic volume.

First survey of atmospheric heavy metal deposition in Kosovo using moss biomonitoring.

Bryophytes act as bioindicators and bioaccumulators of metal deposition in the environment. The atmospheric deposition of Cd, Cr, Cu, Fe, Hg, Ni, Mn, Pb, and Zn in Kosovo was investigated by using carpet-forming moss species (Pseudocleropodium purum and Hypnum cupressiforme) as bioindicators. This research is part of the European moss survey coordinated by the ICP Vegetation, an International Cooperative Programme reporting on the effects of air pollution on vegetation to the UNECE Convention on Long-range Transboundary Air Pollution. Sampling was performed during the summer of 2011 at 25 sampling sites homogenously distributed over Kosovo. Unwashed, dried samples were digested by using wet digestion in Teflon tubes. The concentrations of metal elements were determined by atomic absorption spectrometry (AAS) equipped with flame and/or furnace systems. The heavy metal concentration in mosses reflected local emission sources. The data obtained in this study were compared with those of similar studies in neighboring countries and Europe (2010-2014 survey). The geographical distribution maps of the elements over the sampled territory were constructed using geographic information system (GIS) technology. The concentrations of Cr, Ni, Pb, and Zn were higher than the respective median values of Europe, suggesting that the zones with heavy vehicular traffic and industry emission input are important emitters of these elements. Selected zones are highly polluted particularly by Cd, Pb, Hg, and Ni. The statistical analyses revealed that a strong correlation exists between the Pb and Cd content in mosses, and the degree of pollution in the studied sites was assessed.

Metals in Tortula muralis from sandstone buildings in an urban agglomeration

Acrocarpous mosses present on stonewalls in urban areas may be used for monitoring purposes. Therefore for this investigation we selected Tortula muralis expecting that this species with an ability to colonise buildings in polluted agglomerations where other species have vanished may provide important information to monitor environmental quality. Concentrations of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn in T. muralis, in dust deposited on sandstone surfaces, and in the sandstones on which the moss grew were measured. T. muralis appeared to be a good bioindicator of airborne pollution which accumulated especially extremely high Cu, Fe and Zn concentrations reaching values much higher than harmful for plants. There was no relation between metal concentrations in underlying sandstones and T. ruralis. There was a relation between metal concentrations in dust and T. muralis. Cd, Co, Cr, Mn and V concentrations in T. muralis were higher than in dust. The Self-Organizing Feature Map identifying groups of sampling sites with similar concentrations of metals in mosses was able to classify the pollution level by distinguishing groups of highly, medium and less polluted sites. Once trained, SOFM can be applied in ecological investigations and could form a future basis for recognizing e.g. the type of pollution in urban environments by analysing the concentrations of elements in T. muralis.

Multivariate association of regional factors with heavy metal concentrations in moss and natural surface soil sampled across Norway between 1990 and 2010

Assessing effects of air pollution needs the monitoring of atmospheric deposition. At least for enhancing the spatial resolution of measuring deposition by use of technical devices and of deposition modeling, mosses are used complementarily as biomonitors. In Norway, since 1985, nationwide surveys have been carried out every 5 years. This study aimed at investigating statistical relationships between heavy metal concentrations in samples of moss and natural surface soil, collected in spatial dense networks covering Norway, and regional factors. Heavy metal (HM) concentrations in moss samples collected in 1990, 1995, 2000, 2005, and 2010 and in natural surface soil specimens sampled in 1995 and 2005 across Norway were assessed statistically. Classification and regression trees were computed in order to uncover multivariate relationships between HM concentrations in moss and natural surface soil and potential influencing environmental factors that were integrated into the multivariate analyses. Atmospheric deposition of HM could be proved as the strongest predictor for HM concentrations in moss and natural surface soil samples. Land use within a 5-km radius and population density around the sampling sites were identified as further predictors of HM concentrations in moss and natural surface soil. HM monitoring with moss and natural surface soil samples indicates complementarily atmospheric deposition and thus should be carried out as long-term observation.

Spatial patterns and temporal trends of heavy metal concentrations in moss and surface soil specimens collected in Norway between 1990 and 2010

The aim of this investigation was to inquire whether the spatial patterns and temporal trends of heavy metal concentrations in moss and soil specimen monitored in two spatial dense networks covering Norway are correlated. To this end, data about concentrations of cadmium, mercury and lead in moss and soil specimens collected were compiled. The data were derived from moss surveys conducted in 1990, 1995, 2000, 2005 and 2010, as well as from soil monitoring campaigns in 1995 and 2005. The data sets from both moss and soil surveys indicate a decrease of heavy metal concentrations in moss and soil specimen. However, in case of moss samples, the decrease is by far more pronounced and statistically significant. The heavy metal concentrations in moss and soil are correlated significantly with high positive coefficients for Pb, medium for Cd and moderate for Hg. From a set of potentially influencing boundary conditions, the modelled atmospheric deposition showed the highest correlation with the heavy metal concentrations in moss and soil. The spatial patterns of Cd and Pb concentration in moss and soil specimens 1995 and 2005 are similar. Thereby, the spatial differentiation of concentrations in moss is higher than that in soil, while the opposite holds true for the Hg concentration. Even if the metal concentrations in moss and soil are statistically correlated, they should not be replaced by each other but should be used as complementary monitoring systems.

Modelling and mapping spatio-temporal trends of heavy metal accumulation in moss and natural surface soil monitored 1990–2010 throughout Norway by multivariate generalized linear models and geostatistics

Objective. This study explores the statistical relations between the accumulation of heavy metals in moss and natural surface soil and potential influencing factors such as atmospheric deposition by use of multivariate regression-kriging and generalized linear models. Based on data collected in 1995, 2000, 2005 and 2010 throughout Norway the statistical correlation of a set of potential predictors (elevation, precipitation, density of different land uses, population density, physical properties of soil) with concentrations of cadmium (Cd), mercury and lead in moss and natural surface soil (response variables), respectively, were evaluated. Spatio-temporal trends were estimated by applying generalized linear models and geostatistics on spatial data covering Norway. The resulting maps were used to investigate to what extent the HM concentrations in moss and natural surface soil are correlated. Results. From a set of ten potential predictor variables the modelled atmospheric deposition showed the highest correlation with heavy metals concentrations in moss and natural surface soil. Density of various land uses in a 5 km radius reveal significant correlations with lead and cadmium concentration in moss and mercury concentration in natural surface soil. Elevation also appeared as a relevant factor for accumulation of lead and mercury in moss and cadmium in natural surface soil respectively. Precipitation was found to be a significant factor for cadmium in moss and mercury in natural surface soil. The integrated use of multivariate generalized linear models and kriging interpolation enabled creating heavy metals maps at a high level of spatial resolution. The spatial patterns of cadmium and lead concentrations in moss and natural surface soil in 1995 and 2005 are similar. The heavy metals concentrations in moss and natural surface soil are correlated significantly with high coefficients for lead, medium for cadmium and moderate for mercury. From 1995 up to 2010 the modelled moss and natural surface soil estimates indicate a decrease of lead concentration in both moss and natural surface soil. In the case of the moss data the decrease of accumulation is more pronounced. By contrast, the modelled cadmium and mercury concentrations do not exhibit any significant temporal trend. Conclusions. In Europe, there is hardly any nation-wide investigation of statistical correlations between the accumulation of heavy metals in moss and natural surface soil and potential influencing factors such as atmospheric deposition. This study could show that assessments of heavy metal concentrations in natural surface soil could complement biomonitoring with moss but should not replace it since the heavy metal concentrations in mosses reliably traces the spatial pattern of respective atmospheric deposition. Generalized linear models extend established methods for estimating spatial patterns and temporal trends of HM concentration in moss and natural surface soil.

Monitoring of Metal Deposition by Moss Barbula Constricta J. Linn., from Mussoorie Hills in the India

The moss Barbula constricta J. Linn. was used as an active bio-monitor for estimation of atmospheric metal deposition and its seasonal trend to assess the metal (Zn, Pb, Cu, Cd) status of Mussoorie city and its adjoining areas. Moss transplants were exposed for four months, each period representing winter, summer and monsoon season data at the distances of 0.5, 1.0 and 3.0 km during 2003 to 2007. Significantly higher levels of Zn, Pb, and Cu were measured in the moss harvested at the end of each season. The values of metals at different distances from the city center were higher than in the background samples treated as control. Patterns of moss analysis for seasonal and annual metal data were closely identical. Values of metals were the highest during summer followed by winter, and the lowest in monsoon. It was found that an increase recorded in the sampling sites in the past 5 years could be due to the rapid economic development and the manifold increase in tourist activities. Results from the present moss surveys make the examination of both spatial and temporal trends of metals possible, and also confirm the validity of moss B. constricta J. Linn. as a reliable bio-monitor, and recommend it for the bio-mapping program. Data from existing surveys of metal concentrations in moss is filling a gap due to very limited information available in this field. In addition, it is an invaluable resource for policy makers in preparing the strategies for mitigation. DOI: http://dx.doi.org/10.5755/j01.erem.67.1.1750

Present and Past Deposition of Heavy Metals in Poland as Determined by Moss Monitoring

This study investigates the air deposition of heavy metals (past and recent) in Poland using a common bioindicator – moss Pleurozium schreberi. In 2010 moss samples were collected from 320 sites evenly distributed throughout the country; 297 sites coincided with those in which the 1995 survey was carried out. In green parts of mosses, the concentrations of Cd, Cu, Fe, Pb, and Zn were determined. The 2010 data were compared with those from 1995. The moss concentration of most of the studied metals decreased significantly (P<0.05) between the surveyed years: from 0.45 to 0.30 mg Cd·kg -1 , from 7.6 to 6.0 mg Cu·kg -1 , from 362 to 344 mg Fe·kg -1 , and from 18.8 to 4.9 mg Pb·kg -1 , taking into account median values. This temporal trend was dependent on region (for some provinces decreases were insignificant). The concentration of Zn did not alter in time; median values of this variable were 42.8 and 47.5 mg·kg -1 in 1995 and 2010, respectively. The spatial patterns of the heavy metal concentrations in mosses were similar in both surveys; southern parts of Poland, industrialized and densely populated, were contaminated more than the rest of the country.

Assessing interpolation error for space–time monitoring data

In Europe, since 1990, a survey on environmental monitoring has been taking place every 5 years, using moss samples to study the distribution of heavy metal concentration and assess contamination sources, resulting on the identification of statistical association of several heavy metal concentrations in mosses. With this work, we propose an extension of an existing spatio-temporal model, introduced in Host et al. (JASA 90(431):853–861, 1995), allowing for prediction at unsampled locations of pollution data in the presence of covariates related to each country specificities, when separately modelling the spatial mean field, the spatial variance field and the space–time residual field. Moreover, this model allows to estimate an interpolation error, as an accuracy measure, derived dependently on the case study. For a validation purpose, a simulation study is conducted, showing that the use of the proposed model leads to more accurate prediction values. Results obtained by the proposed methodology for the most recent available survey, are compared with results obtained with no temporal information, namely when Ordinary Kriging, according to the definition in Cressie (Statistics for spatial data, Wiley, New York, 1993), is used to derive illustrative prediction maps based only on the most recent data. An exercise of cross-validation is performed relative to each of the scenarios considered and the average interpolation errors are presented. While assessing interpolation errors, we conclude that the monitoring specificities of each country and the information of preceding surveys allow for more accurate prediction results.

Correlation between atmospheric deposition of Cd, Hg and Pb and their concentrations in mosses specified for ecological land classes covering Europe

Referring to Europe as a whole and to single European countries, previous studies have shown that heavy metal concentrations in mosses (1) are primarily determined by atmospheric deposition of heavy metals; (2) are country and element–specific; and (3) agree well with respect to element–specific spatial patterns and temporal trends of atmospheric deposition of heavy metals. This paper investigates correlations between the concentrations of cadmium, lead and mercury in atmospheric deposition and mosses within the units of an ecological land classification of Europe. To this end, measurements from the 2005/2006 European moss survey and modeled atmospheric deposition in the previous three years were intersected with a map on ecologically defined land classes of Europe. Then, the minimum numbers of sampling sites required within the ecological land classes were computed. Considering spatial auto–correlations, subsequently the correlations between the concentrations of heavy metals in mosses and corresponding deposition were calculated and mapped for each of those ecological land classes containing moss sampling sites. It was concluded that the numbers of sampling sites within Europe and most participating countries as well as within most of the ecological land classes are sufficient for estimating the mean of measurements for the above mentioned three spatial levels within 20% of its true value with 95% confidence. Spatial patterns of correlations between the atmospheric deposition and bioaccumulation were shown to vary by element and ecologically defined land classes.

Does heavy metal deposition affect nutrient uptake by mossPleurozium schreberi?

Heavy metals may influence chemical composition of plants, and thus shape elemental stoichiometry of plant communities. That is because some physiological processes aiming at neutralization of contaminant toxicity require increased acquisition of some nutrients (e.g. N, S, P or Ca). The aim of the study was to evaluate the heavy metal deposition in Poland using moss Pleurozium schreberi as a bioindicator, and check whether C/N, C/S, C/P and Ca/Mg ratios in mosses correspond with the accumulation of heavy metals. Heavy metal concentrations in mosses were highly variable across the study area – southern parts of the country, industrialized and densely populated, were the most contaminated. There were significant correlations between nutrient ratios and metal accumulation in mosses. Mosses seem to take 1) more N, P and S under Cu contamination, and 2) more Ca under Zn contamination. This increased acquisition of nutrients, mainly N and Ca, may be a response to higher toxicity of heavy metals. Further studies are required to exclude other causes for observed relationships.

Fractionation of trace metals in a contaminated freshwater stream using membrane filtration, ultrafiltration, DGT and transplanted aquatic moss

Four metal speciation and fractionation techniques – DGT (diffusive gradients in thin films), 1-kDa ultrafiltration, 0.22-µm membrane filtration and aquatic moss – were simultaneously applied to a small, contaminated freshwater stream in northern Sweden to investigate differences and similarities between the methods regarding trace metal speciation and their dependence on geochemical water properties. The investigated metals comprise Al, Cd, Co, Cu, Fe, Mn, Ni, and Zn. The normal DGT devices with Chelex cation exchanger were used. Shoots from the aquatic moss Fontinalis antipyretica L ex Hedw. were collected in a non-polluted brook and transplanted to the sampling site for exposure. It was evident that 0.22-µm membrane filtration, 1-kDa ultrafiltration and DGT generally measured different metal fractions where &lt;1-kDa ultrafiltered concentrations were lower than DGT labile concentrations which in turn were lower than &lt;0.22-µm concentrations. The differences between DGT and &lt;1-kDa concentrations indicate the occurrence of labile colloids discriminated by ultrafiltration. Strong correlations between DGT and &lt;1 kDa concentrations were found for Al, Cu, Cd, Co and Zn. Despite a rigorous sample cleaning, retention of particulate matter on the moss samples was revealed by a significant correlation between metal concentrations in moss and particulate Fe. Generally, elevated trace metal concentrations were found in moss exposed at the sampling site compared to reference moss from the non-polluted brook. No significant correlations were found between DGT-labile concentrations and moss concentrations. Supplementary material: DGT – labile concentrations of Al, Cd, Co, Cu, Fe, Mn, Ni and Zn from deployments in Gråbergsbäcken Stream is available online at http://www.geolsoc.org.uk/SUP18566 . A hard copy can be obtained from the Society Library.