2 research outputs found
Metallakkumulation in Moosen: Standörtliche und regionale Randbedingungen des Biomonitoring von Luftverunreinigungen [Metal accumulation in mosses: local and regional boundary conditions of biomonitoring air pollution]
Metal accumulation in mosses: Local and regional boundary
conditions of biomonitoring air pollution
Goal and Scope. Several studies show that the concentration of
metals in mosses depends not only on metal deposition but also
on factors such as moss species, canopy drip, precipitation, altitude,
distance to the sea and the analytical technique used. However,
contrasting results have been reported and the interpretation
of the spatial variability of the metal accumulation in mosses
remains difficult. In the presented study existing monitoring data
from the European Heavy Metals in Mosses Surveys together with
surface data on precipitation, elevation and land use are statistically
analysed to assess factors other than emissions that have an
influence on the metal accumulation in the mosses.
Main Features. Inference statistics and Spearman correlation analysis
were applied to examine the association of the metal accumulation
and the distance of the monitoring sites to the sea as well as
the altitude. Whether or not significant differences of the metal
loads in the mosses exist at national borders was examined with
help of the U-test after Mann and Whitney. In order to identify
and rank the factors that are assumed to have an influence on the
metal uptake of the mosses Classification and Regression Trees
(CART) were applied.
Results. No clear tendency could be derived from the results of
the inference statistical calculations and the correlation analyses
with regard to the distance of the monitoring site to the sea and
the altitude. According to the results of the CART-analyses mainly
the moss species, potential emission sources around the monitoring
sites, canopy drip and precipitation have an effect on the metal
bioaccumulation. Assuming that each participating country followed
strictly the manual for sampling and sample preparation
the results of the inference statistical calculations furthermore
suggest that in most cases different techniques for digestion and
analysis bias the measurements significantly.
Discussion. For the first time a national monitoring data base consisting
of measurement data and metadata as well as surface information
on precipitation, land use and elevation was applied to examine
influence factors on the metal bioaccumulation in mosses.
The respective results mirror existing knowledge from other national
studies to a large extend, although further analyses are necessary
to affirm the findings. These analyses should include data
from other national monitoring programmes and should additionally
be carried out with other decision tree algorithms than CART.
Conclusions. The local variability in the metal concentration in
mosses can be uncovered in terms of predictors or underlying
hidden causes by using CART. Ideally, such an approach should
be applied across the whole of Europe. This will only be feasible
if all participating countries provide additional information about
site characteristics as currently is done in for example the German
moss surveys.
Recommendations. The UNECE Metals in Mosses Survey experimental
protocol should be improved in order to reduce the observed
influences, to enhance standardisation, and to strengthen
the quality control. This implies the integration of sampling site
describing metadata into the assessment. Furthermore, basis research
is needed to test the hypothesis concerning moss speciesspecific
accumulation of depositions.
Perspectives. Provided that the presented results hold true in further
analyses correction factors should be applied on the moss
data in order to get the depicted spatial patterns and temporal
trends of metal bioaccumulation unbiased. Such factors should
be calculated for natural landscape units or ecoregions that are
homogeneous with regard to climate, vegetation and altitud