Heavy metal and nitrogen concentrations in mosses are declining across Europe whilst some "hotspots" remain in 2010.

In recent decades, naturally growing mosses have been used successfully as biomonitors of atmospheric deposition of heavy metals and nitrogen. Since 1990, the European moss survey has been repeated at five-yearly intervals. In 2010, the lowest concentrations of metals and nitrogen in mosses were generally found in northern Europe, whereas the highest concentrations were observed in (south-)eastern Europe for metals and the central belt for nitrogen. Averaged across Europe, since 1990, the median concentration in mosses has declined the most for lead (77%), followed by vanadium (55%), cadmium (51%), chromium (43%), zinc (34%), nickel (33%), iron (27%), arsenic (21%, since 1995), mercury (14%, since 1995) and copper (11%). Between 2005 and 2010, the decline ranged from 6% for copper to 36% for lead; for nitrogen the decline was 5%. Despite the Europe-wide decline, no changes or increases have been observed between 2005 and 2010 in some (regions of) countries.

Clover as an indicator plant for phytotoxic ozone concentrations: visible injury in relation to species, leaf age and exposure dynamics.

Visible ozone injury on leaves of three clover species was investigated in relation to species, leaf age and exposure dynamics. It was shown that ozone episodes in south-west Sweden cause visible injury to subterranean clover (Trifolium subterraneum L.), white clover (Trifolium repens L.) and red clover (Trifolium pratense L.). Trifolium subterranean was most sensitive to ozone, whilst T. pratense was least sensitive. Application of the anti-ozonant, ethylenediurea (EDU), reduced the extent of visible ozone injury, but did not give complete protection with the concentrations used. Similarly, filtration of the air reduced the extent of visible injury in T. subterraneum enclosed in open-top chambers. EDU-treated plants of T. subterranean accumulated more biomass than the non-EDU treated plants after a period with rather high ozone concentrations, while the opposite occurred for T. pratense. Experiments with T. subterraneum in open-top chambers also showed that older leaves were more sensitive to ozone than younger leaves and that a shorter period with higher ozone concentrations produced more ozone injury than a longer period with lower ozone concentrations, although the two periods had the same number of ppb-hours.