The multi-element content of the lichen Parmelia sulcata, soil, and oak bark in relation to acidification and climate.

Understanding how biodiversity is influenced by changing atmospheric conditions is important for conservation, public policy and environmental health. In a recent study, an impact on two of the most abundant lichens in Europe (Parmelia sulcata and Hypogymnia physodes) was recorded at Burnham Beeches lying 40 km west of London (UK) during unusual atmospheric conditions whilst other species remained unaffected. Bark and soil chemistry also influence lichen vitality and community composition. Correlations between element concentrations and element ratios in different samples help understand element cycling. To study this further, the multi-element content of the lichen P. sulcata and bark sampled in 2000 from 16 oak (Quercus robur) trees at Burnham Beeches was compared with the same elements determined in 24 surface soils sampled in 2005 from beneath the same trees. Soil pH ranged from 4.1 to 6.7. Highly significant correlations (p<0.001) for Mn/Ca ratios in lichen versus bark, soil versus bark and soil versus lichen samples confirmed cycling via the soil-tree-lichen system. Similar Mn/Ca ratios were reported in coniferous forests where high Mn concentrations were shown to limit epiphytic lichen abundance. Soil acidification influences element bioavailability and bark chemistry in Burnham Beeches with implications for lichen diversity and health. Recovery was recorded in P. sulcata, including regeneration within monitoring quadrats. Biological systems are well known to be influenced by pollution episodes.

Effect of bone meal (calcium phosphate) amendments on metal release from contaminated soils--a leaching column study.

Metal-contaminated soil may be remediated in situ by the formation of highly insoluble metal phosphates if an appropriate phosphorus (P) source can be found. Leaching column experiments have been carried out to assess the suitability of bone meal as such a source. Bone meal additions reduced metal release from a contaminated soil, increased soil and leachate pH and decreased soil leachate toxicity. Minimal P leaching occurred from the soil. The data are consistent with a proton consuming bone meal (calcium phosphate) dissolution reaction followed by the formation of metal phosphates. Although, no metal phosphates were observed to form using X-ray diffraction of scanning electron microscopy this could be due to their low concentration. Relatively low (1:50 bone meal:soil) concentrations of fine (90-500 microns) bone meal would appear to be an effective treatment for metal-contaminated soils.