The Accumulation of Poisonous Elements in Populus × euramericana ,Salix matsudana,Ulmus pumila and Robinia pseudoacacia Growing on Coal Ash“Soil”

The speciai“soil”type condition is formed by filling the collapsed area withcoal ash from thermal power factory and covering 30 cm Chao soil onto the ash. In 1986～1987, Populus × euramericana, Salix matsudana,Ulmus pumila and Robinia pseudoacaciaplantations were established on the site. Under intensive cultivation,they grew well.Biomassand 14 elements distribution and accmulation,in the trees were investigated in 1991.The re-sult shows that most elements such as N,P, K,Ca,Mg were accumulated mainly in leaf,thenroot,bark and branch,their contents in trunk the least.Among the 4 species,Robinia pseu-doacacia had the highest N content.The accumulation of the poisonous elements in tree wasHg mainly in root and bark,seldom in leaf and branch;Pb mainly in leaf and bark,seldom intrunk;Cd and Cr distributed evenly in all organs. The absorption of nutritive and poisonouselements was calculated by their 4～5 years biomass and element contents. The trees purifica-tion function was discussed based on the calculation.