Wet deposition of ²¹⁰ Pb aerosols over two areas of contrasting topography

Abstract

Deposition fluxes of 210 Pb on low and moderately high-elevation sites of Edinburgh (Scotland) and mid-Wales, respectively, have been measured. The excess 210 Pb fluxes in moorland Edinburgh soils did not vary significantly and ranged from 71 to 92 Bq m −2 y −1 with a mean value of 78 ± 9 Bq m −2 y −1 , for all the measured sites where both altitude and the mean annual rainfall are similar. On the other hand, the excess 210 Pb measured in moorland soils of mid-Wales sites increased by a factor of 2.4 at or near the summit (741 m asl) relative to the coast (∼15 m asl), whereas rainfall increased by a factor of 1.8 over the same height range. On average, the summit to valley ratio of 210 Pb concentration in rainfall was a factor of 1.3 due to scavenging of the feeder clouds by the seeder rain. These results are consistent with results for both modelled and field studies on the wet deposition of pollutants in complex terrain reported by several researchers. The long-term 210 Pb wet deposition field data will provide an important input parameter for the modelling of wet deposition of aerosols throughout the uplands of the UK and elsewhere where the seeder-feeder process is of common occurrence.

Stable (206Pb, 207Pb, 208Pb) and radioactive (210Pb) lead isotopes in 1year of growth of Sphagnum moss from four ombrotrophic bogs in southern Germany: Geochemical significance and environmental implications

“…In contrast to Neuherberg (855 mm precipitation from 1972 to 1999), the peat bogs studied here experience annual precipitation ranging from 1300 to 1900 mm (Table 1). There is a strong and well established correlation between 210 Pb deposition to terrestrial ecosystems and amount of precipitation (Hill, 1960;Winkler and Rosner, 2000;Garcia-Orellana et al, 2006;Likuku, 2006). Given the linear regression of 210 Pb deposition versus precipitation for a large number of studies in Europe (Garcia-Orellana et al, 2006;Le Roux et al, 2008), total 210 Pb deposition to the four bogs studied should be much greater than at Neuherberg.…”

“…At GS, site I and II are located nearly 400 m away from the other sampling sites within a more forested and, thus, more sheltered area; all other sites were on the same bog area which was more open to winds from the west and had only scattered Pinus mugo stands on the surface. Greater accumulation rates of 210 Pb in forested soils compared to soils from open meadows and pastures are well documented (Likuku, 2006;Likuku et al, 2006), and interception of aerosols by the tree canopy at site I and II of GS may be responsible for the anomalous 210 Pb activities.…”

“…0.4 lm after 1 week (Bondietti et al, 1988) which is also the average residence time of 210 Pb-bearing aerosols in the atmospheric boundary layer (Liu et al, 2001). The supply of atmospheric 210 Pb to the soils and plants of terrestrial ecosystems, therefore, is very strongly correlated with the amount of precipitation (Hill, 1960;Winkler and Rosner, 2000;Garcia-Orellana et al, 2006;Likuku, 2006). However, occult deposition might be important at high altitude sites (Graustein and Turekian, 1989;Le Roux et al, 2008).…”

Effect of snow cover on pan-Arctic permafrost thermal regimes

“…For example, SND in northernmost Siberia displayed strong positive anomalies during 2001-2009. Recent studies have linked the loss of Arctic sea ice to the increased SND in these regions (Ghatak et al 2010;Cohen et al 2012;Park et al 2013b). The open water caused by loss of sea ice is likely to enhance the latent heat flux with the atmosphere and therefore to generate an increase in precipitating clouds over the Arctic (Eastman and Warren 2010;Stroeve et al 2011).…”

“…Among the regionally varying trends in SND, significant increases have been identified mainly in coastal regions rather than in interior areas (Park et al 2013b). The decline in Arctic sea ice cover may be associated with increases in SND over northern regions (Ghatak et al 2010;Cohen et al 2012;Park et al 2013b). However, a data-based analysis has revealed increased poleward atmospheric moisture transport (Zhang et al 2013), implying higher precipitation and therefore increases in SND in the Arctic.…”