Effects of atmospheric deposition, soil pH and acidification on heavy metal contents in soils and vegetation of semi-natural ecosystems at Rothamsted Experimental Station, UK

摘要: The effects of acidification on the soil chemistry and plant availability metals Pb, Cd, Zn, Cu, Mn Ni in new archived samples taken from >100-year-old experiments natural woodland regeneration (Geescroft Broadbalk Wildernesses) a hay meadow (Park Grass) at Rothamsted Experimental Station are examined. We measured significant input atmospheric deposition, enhanced under by 33% (Ni) to 259% (Zn); Pb deposition was greatly influenced vehicle emissions introduction petrol. build up long-term acidification, mobilization leaching, but generally, only occurred soils pH<4. Cd were most sensitive acidity with effective occurring pH 6.0–5.5 (0.01 M CaCl2), followed Cu 5.5–5.0. not mobilized until pH<4.5. Acidification 4 60–90% total this adsorbed onto ion exchange surfaces and/or complexed organic matter. This buffering effect matter down generally reflected all investigated. For grassland maximum accumulation herbage corresponded 4.0. concentration oak saplings (Quercus robur) 3-, 4- 6-fold larger than 7. Mature Oak trees contained 10 times more Mn, 3 their leaves At values <4.0 metal content declined. Only for Zn did reflect decline available attributed acid weathering leaching. chief cause species richness increased dominance two acid-tolerant, metal-excluder