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A Carballeira

Publications and source records attributed to A Carballeira.

At least 19 recordsLinked to original sources
PubMed2006

Testing the use of juvenile Salmo trutta L. as biomonitors of heavy metal pollution in freshwater.

Individual specimens of Salmo trutta were captured, from four sampling sites in Galician rivers (NW Spain) affected by different types of contamination: diffuse urban waste, run-off from an unrestored dump at a copper mine and waste from a fish farm. The ages of the captured trouts were established and only those belonging to the 1+ age class were selected for study. The liver and kidney were removed from each fish and analysed to determine the tissue concentrations of Cu, Fe and Zn. The results obtained showed that: (i) the use of 1+ individuals allowed differentiation of contamination scenarios on the basis of the tissue concentrations of metal; (ii) the use of 1+ individuals allowed standardization of the time of exposure, which was sufficiently long for differential uptake to have taken place; (iii) liver tissue provided the best results as, less effort was required than for processing kidney tissue, and significant differences between sampling sites were detected because the intrapopulational variability in metal levels was lower than for kidney, and (iv) the levels of elements detected were not affected by basal tissue concentrations or residual concentrations due to past contamination, which older trouts may have been exposed to. In addition, the use of 1+ trout may provide better results in annual environmental sampling surveys.

Aging↗
PubMed2006

Lolium perenne as a biomonitor of atmospheric levels of fluoride.

The aim of the present study was to develop a standardised protocol for the use of Lolium perenne cultures to biomonitor the surroundings of an aluminium smelter. Five ecological stations, which corresponded to air quality network monitoring sites pertaining to the smelter, were selected for study. Cultures of L. perenne (one at each site) were exposed for approximately 28 days, at different times between August 1999 and October 2000. At the end of the exposure periods, the fluoride concentrations in the cultures were determined. The concentrations of fluoride determined in the L. perenne cultures varied from 4.32 microg g(-1) to 912.22 microg g(-1) and followed a similar trend to concentrations of atmospheric fluoride. However, a wider range of fluoride concentration was observed in the L. perenne cultures than in the air surrounding the smelter. The background levels of fluoride in L. perenne cultures were also calculated, thereby allowing classification of fluoride air pollution in the area under study.

Air Pollutants↗
PubMed2006

Considerations on the sample size of wood mice used to biomonitor metals.

The concentrations of various metals (Zn, Cu, Mn and Cr) in liver, kidneys and brain from specimens of the wood mouse Apodemus sylvaticus captured from 5 sites were measured. Two of the sites were in a restored mine dump, another in an area characterized by serpentized soils and the remaining two were control sites. The sample size required for statistical differentiation of the sampling sites was calculated from the mean values and the variability in bioaccumulation corresponding to each of the sites. The relationship between the sample size and the results of the statistical test used to reveal significant differences between the mean concentrations of metals in organs from A. sylvaticus is demonstrated. The homeostatic control exerted by the wood mice on the tissue levels of metals reduced the interpopulational variability, thereby homogenizing the mean bioaccumulation corresponding to the different sampling stations. The sample size, tissue regulation of the levels of heavy metals and the patterns of variability are of vital importance in evaluating the usefulness of A. sylvaticus as a biomonitor of heavy metals.

Animals↗
PubMed2005

Definition and number of subsamples for using mosses as biomonitors of airborne trace elements.

We collected 50 subsamples of the moss Scleropodium purum from each of three sampling sites and determined the concentrations of As, Cd, Cu, K, Hg, Ni, Pb, Se, and Zn in each subsample. We then calculated the number of subsamples required to determine significant differences in the mean concentrations of two sampling sites. We found that to differentiate between an uncontaminated sampling site and another, slightly contaminated site, 30 subsamples are required from each. On the basis of these results and because, to date, there are no studies that justify the application of the previously proposed recommendations, studies of local variability in other areas, and under different conditions, with other contaminants and moss species must be undertaken. For posterior comparison of data on variability as well as application of the recommendations associated with such results, the general use of a single definition of a subsample is required. We propose the following definition of a subsample: "1 g dry weight (approx.), collected within a 25-cm radius of a node, selected at random from a 1 x 1-m sampling grid placed in a sampling site."

Air Pollution↗
PubMed2005

Modelling the extra and intracellular uptake and discharge of heavy metals in Fontinalis antipyretica transplanted along a heavy metal and pH contamination gradient.

Samples of the aquatic bryophyte Fontinalis antipyretica Hedw. were transplanted to different sites with the aim of characterizing the kinetics of the uptake and discharge of heavy metals in the extra and intracellular compartments. The accumulation of metals in extracellular compartments, characterized by an initial rapid accumulation, then a gradual slowing down over time, fitted perfectly to a Michaelis-Menten model. The discharge of metals from the same compartment followed an inverse linear model or an inverse Michaelis-Menten model, depending on the metal. In intracellular sites both uptake and discharge occurred more slowly and progressively, following a linear model. We also observed that the acidity of the environment greatly affected metal accumulation in extracellular sites, even when the metals were present at relatively high concentrations, whereas the uptake of metals within cells was much less affected by pH.

Aluminum↗
PubMed2005

Mapping the results of extensive surveys: the case of atmospheric biomonitoring and terrestrial mosses.

In this paper we discuss some difficulties associated with the process of constructing maps of pollution from data obtained in surveys covering extensive areas. As we show here, these problems may be wide-ranging but are seldom recognized by investigators. The origin of the problems is the existence of multiple sources of pollution in the study area, each of different intensity and affecting areas of different extent. The particular spatial structure of the pollution sources interacts with the spatial layout of the samples, resulting in data sets with distributions that are very different from the usually assumed normal distribution, and characterized by heavy tails and gross outliers. These distributions arise because of incomplete sampling of small-scale pollution processes (i.e. those occurring on a spatial scale smaller than the spatial scale of the sampling grid). After discussion of the potential problems and appropriate techniques for analyzing this kind of data, we applied the proposed techniques to a real data set of heavy metal contents in terrestrial mosses. From the exercise we concluded that a) the first step in analysis of this kind of data must be to check for the presence of spatial structure on scales larger than the sampling grid, to avoid mapping noise, and b) the map generated must not contain information about pollution sources with a spatial scale smaller than the spatial scale of the sampling grid. We present and discuss the performance of robust statistical methods of testing for spatial structure (based on robust variograms and randomization testing) and of filtering the small-scale spatial processes (using median-polishing) prior to mapping.

Atmosphere↗
PubMed2005

The effect of sampling design on extensive bryomonitoring surveys of air pollution.

In this study, we investigated if the different sampling designs normally used in extensive bryomonitoring surveys of air pollution allow compliance with the objectives proposed in the 'Heavy Metals in European Moss' project. For this, we have used data on concentrations of As, Cu, Se and Zn from five moss sampling surveys carried out in Galicia (NW Spain), using three types of sampling design: regular grid, sampling sites inside squares and the strategy recommended in the guidelines for European surveys. To study the effect of the interaction between the sampling design and the spatial pattern of the presence of contaminants, we have used a simulated and a real pattern onto which we superimposed the three sampling designs considered. We found that only random sampling and grid sampling allow compliance with the proposed objectives, and we discuss the advantages of the latter over the former. The data corresponding to studies using different sampling designs are not comparable, and in future large-scale surveys, the same design must be used if the results are to be compared and if valid conclusions are to be reached. The scale of the grid determines the scale to which the objectives are complied with, so that for correct standardization of the technique, and taking into account the most commonly used grid sizes, we recommend a grid size of 30 x 30 or 32 x 32 km. When additional samplings are required, the size of the grid size should be 30/2(n) or 32/2(n) km.

Air Pollution↗
PubMed2004

Active biomonitoring of element uptake with terrestrial mosses: a comparison of bulk and dry deposition.

Moss (Scleropodium purum) transplants were used to study bioconcentration originating from dry and bulk deposition, by measuring the tissue contents of Al, As, Ca, Cu, Fe, Hg, Mn, Ni, Pb, Se and Zn. Furthermore, a laboratory experiment was carried out to determine the sequence of maximum concentration and affinity of Al, Cu, Fe, Hg, Ni, Pb and Zn, in S. purum. We found that in many of the transplants, for the same period of exposure, higher levels of metals were accumulated via dry deposition than via bulk deposition. This result may be explained by the simple washing action of the rain on the surface of the moss, and by the existence of processes that provoke the loss of some of the accumulated elements: intercationic displacement and leaching caused by acid precipitation. Modelling of the final bioconcentration observed, as a balance of inputs and outputs of elements, revealed that this terrestrial moss does not integrate, but rather concentrates atmospheric deposition, and there exists a state of unstable equilibrium between inputs and outputs of elements, a state that is determined by the characteristics of the surrounding environment. On the basis of the results obtained in this study, we can conclude that at present, it is not possible to extrapolate the calibrations between the concentrations of elements accumulated in a certain species of moss to values of atmospheric deposition (bulk deposition) from one place to another with different environmental conditions.

Acid Rain↗
PubMed2004

A new method for testing the sensitivity of active biomonitoring: an example of its application to a terrestrial moss.

For the first time, the concepts of limit of detection and limit of quantification, commonly used in analytical chemistry, are applied to the field of active biomonitoring with terrestrial mosses, using the controls as blanks so that the limits indicate the error associated with the transplant technique. The application of these concepts to data corresponding to Hg concentrations in the surroundings of a chlor-alkali plant and a power plant, makes interpretation of the results easier by providing better spatial and temporal coherence. This procedure may allow improvement in the standardization of active biomonitoring techniques as it is applicable to all kinds of biomonitors. One disadvantage of the application of the limit of detection and limit of quantification is that they only take into account the alpha error, or risk of false positives, and do not take into account the beta error, or risk of false negatives.

Adaptation, Physiological↗
PubMed2004

Identification of pollution sources by means of moss bags.

Moss bags containing Scleropodium purum were exposed for 30 days in an industrial area in which a chlor-alkali plant (CAP) and a concrete factory (CF) are located close to one another (121 m). Following the exposure, the transplanted mosses were analyzed to determine levels of Hg, Zn, Ni, and Cr. The enrichment factors (EFs) of the metals (final concentration/initial concentration) were calculated; the mean values obtained were 26.4 for Hg, 6.6 for Zn, 1.07 for Ni, and 1.0 for Cr. Dispersion of Cr and Ni was closely related, probably because they were dispersed together on the same particle. The spatial structure of the data was examined, and significant fits to the semivariograms were found for Hg, Zn, and Cr, using kriging to interpolate the data. Using this technique, it was possible to estimate where the maximum concentrations of elements occurred, allowing us to distinguish from which focal point they were emitted: Hg from the CAP, and Zn and Cr from the CF. The combined use of moss bags and geostatistical techniques allowed characterization of the emissions and identification of focal points of contamination in the study area.

Air Pollutants↗
PubMed2002

Biomonitoring of metal deposition in northern Spain by moss analysis.

The results of the first survey carried out in northern Spain to determine atmospheric deposition of metals by analysis of terrestrial mosses, are described. Samples of different mosses, mainly Hypnum cupressiforme and Scleropodium purum, were collected from 134 sampling sites, between 1995 and 1996. Levels of Al, As, Cr, Cu, Fe, Hg, Ni, Pb and Zn, were determined by flame atomic absorption or atomic fluorescence spectrophotometry. Regression analysis was used to compare the capacity of the selected moss species to accumulate the elements, and intercalibration of accumulation in these species was carried out where necessary. Distribution maps were prepared to allow the zones most affected by metal deposition to be identified and to relate this to known sources of contamination: electricity power stations and other industries (e.g. Hg and Ni), edaphic contamination (e.g. Al and Cr) and road traffic (Pb). Background levels of metals in each species were also determined for the study area.

Bryopsida↗
PubMed2002

Biomonitoring metal deposition in Galicia (NW Spain) with mosses: factors affecting bioconcentration.

Three factors (canopy effect, lithology and seasonal variations) that may influence the concentrations of metals in terrestrial mosses were studied. The levels of 17 elements were determined in terrestrial mosses (Scleropodium purum (Hedw.) Limpr, and Hypnum cupressiforme Hedw.) collected from 75 sites in Galicia at two sampling times, in 1995 and 1997. In addition, monthly samples of S. purum were collected throughout a period of one year from four sites in the same area, for analysis of levels of eight elements. The first studied factor, collection of mosses from areas under tree cover, did not influence significantly the levels of the elements analysed. The second factor studied was the dominant lithology in the sampling area (granite, slate and schist). No significant differences were found between samples from sites where granites and slates dominated. Significant differences were found in the levels of Co, Cr, Ni and Mn in both species growing in granite and slate substrate areas when compared with those growing in schist areas. This was also found for Al and Fe in S. purum and for As in H. cupressiforme. The third factor investigated, using the results from the monthly survey, was the seasonal effect. No significant differences were found in the concentrations of all elements in S. purum throughout the year.

Air Pollutants↗
PubMed2002

Bioconcentration of metals in the moss Scleropodium purum in the area surrounding a power plant. A geotopographical predictive model for mercury.

Samples of the moss Scleropodium purum collected in 1995 and 1997 were used to biomonitor the deposition of metals in the area surrounding a thermal power plant. Significantly higher levels of Cu (p < 0.05), Fe (p < 0.01), As and Hg (p < 0.001) were found in the 1997 samples than in the 1995 samples, due to changes in atmospheric conditions. The influence on bioconcentration of the orientation of the sampling sites relative to the source of emission was studied. It was found that the increase recorded in 1997 generally occurred in the sampling sites in the south east of the study area. Analysis of the effect of distance from the source of emission revealed that the increase in metal levels in 1997 took place close to the power station (10-30 km). Finally, multiple regression analysis was used to construct a model that related different topographical variables to the concentrations of Hg in moss. The model, constructed using the data collected in both sampling periods, included the orientation of the sampling sites relative to the source of emission as well as the height of sampling sites in 1995 and the distance from the emission point in 1997. The model allowed us to determine the extent of the area affected by deposition and to establish the magnitude of deposition.

Air Pollutants↗
PubMed2002

Seasonal variation and background levels of heavy metals in two green seaweeds.

Seasonal variation in the contents of different metals (Al, Cr, Cu, Fe, Mn, Ni and Zn) in two genera of macroalgae, Ulva and Enteromorpha was studied at 22 sites on the northwest coast of Spain. The seasonal variation in the different metals followed a similar pattern in both seaweeds and appeared to be caused by dilution during the period of maximum growth and concentration during periods of slow growth. Fluvial inputs of Al, Fe and Mn in autumn and winter appeared to accentuate the latter effect: the concentrations of these three metals in both macroalgae and of Cr in Enteromorpha were highest at those sites most influenced by inputs from rivers. The background levels of Cr, Cu, Ni and Zn in the algae in summer and winter were established.

Chlorophyta↗
PubMed2001

Evaluation of contamination, by different elements, in terrestrial mosses.

Evaluation was made of the degree to which samples of terrestrial mosses (Scleropodium purum and Hypnum cupressiforme) collected in Galicia (NW Spain) were contaminated by different elements. The concentrations of Al, As, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, Pb, S, Se, and Zn in the mosses were determined, then the contamination factors were calculated by dividing each value by the corresponding background level of that element. To assess contamination using contamination factors (CFs), a scale was established that allowed categorization of sampling sites for each element determined. The proposed scale comprises six categories, ranging from CF values of less than 1 (no contamination) to values of greater than 27 (extreme contamination). Finally, all available information was brought together and summarized in a contamination index. This index has the advantage that it takes into account the toxicity of the elements and that can be used with an already existing scale of classification.

Air Pollution↗
PubMed2001

A comparison of indigenous mosses and topsoils for use in monitoring atmospheric heavy metal deposition in Galicia (northwest Spain).

Samples of moss (Scleropodium purum or, in its absence, Hypnum cupressiforme) and of topsoil (0-5 cm) were collected in the spring of 1995, from 75 sites distributed throughout Galicia (northwest Spain) in order to compare the potential usefulness of each in evaluating the atmospheric deposition of contaminants. Analysis was made of the total content of various metals in the moss and of different soil metal fractions (including total metal content, labile metals and metals bound to organic material). We found that the labile fraction most closely resembled the metal content of the moss. Calculation of enrichment factors allowed us to show that the soil was not, except in the case of Cr, the main source of contamination in the moss. By comparing contamination factors of metals in moss and soil fraction samples we found that moss samples were more useful for evaluating the degree of contamination at different sites.

Air Pollutants↗
PubMed2001

Sampling optimization, at site scale, in contamination monitoring with moss, pine and oak.

With the aim of optimizing protocols for sampling moss, pine and oak for biomonitoring of atmospheric contamination and also for inclusion in an Environmental Specimen Bank, 50 sampling units of each species were collected from the study area for individual analysis. Levels of Ca, Cu, Fe, Hg, Ni, and Zn in the plants were determined and the distributions of the concentrations studied. In moss samples, the concentrations of Cu, Ni and Zn, considered to be trace pollutants in this species, showed highly variable long-normal distributions; in pine and oak samples only Ni concentrations were log-normally distributed. In addition to analytical error, the two main source of error found to be associated with making a collective sample were: (1) not carrying out measurements on individual sampling units; and (2) the number of sampling units collected and the corresponding sources of variation (microspatial, age and interindividual). We recommend that a minimum of 30 sampling units are collected when contamination is suspected.

Air Pollutants↗