Comparison of two monitoring systems for Cu and Mo in the Swedish environment

Bio-geochemical samples (BGS) are roots of certain aquatic plants and mosses suitable for monitoring elements dissolved in stream water. The moose, a wild ruminant living in most parts of Sweden, represents higher trophic level and another manifestation of bioavailability. By analyzing BGS (n≈33 600) and moose liver (n≈2400), a systematic survey has been performed in the terrestrial environment of Sweden. Cu and Mo are essential elements for life, and their presence is especially important for the Cu-dependent processes in ruminants. The availability of Cu and Mo as monitored in BGS and moose was visualized in the form of maps and subjected to further statistical analysis. The medians, with lower and upper quartiles indicated as intervals, for the country as a whole were: moose liver, Cu=34 (20–59), Mo=0.82 (0.58–1.06) mg kg−1 wet weight; BGS, Cu=50 (35–77), Mo=9.0 (5.3–18.0) mg kg−1 dry weight. The ranges of medians for the 22 Swedish counties were: moose liver, Cu=(20–62), Mo=(0.54–1.18) mg kg−1 wet weight; BGS, Cu=(28–115), Mo=(5–47) mg kg−1 dry weight. The relationships between the counties and the connections between the monitoring variables were elucidated by principal component analysis (PCA). It was demonstrated that two monitoring systems could give divergent results. An unexpectedly strong negative correlation was found between the county medians for Cu in BGS and moose liver. A possible explanation, based on the interaction between Cu and Mo in moose, could not be verified.