Preliminary Study On Sources And Accumulation Of Heavy Metal Contents Of Epiphytic Bryophytes

Bryophytes are used as biomonitor in the field of environmental monitoring in many countries because of its well known advantages of sensitivity of environment's changes, which much attention has been paid to. Bryophytes'monitoring on heavy metals by its heavy metal contents is an important part of bryophytes'monitoring factors, which caused the focusing researches on the sources of heavy metal contents in bryophytes in recent years. The epiphytic bryophytes Haplocladium microphyllum and Entodon compressus which distribute extensively in Nanjing were studied in Zhongshan Botanical Garden, Zhongshan Tea-plantation, Qingliang Hill Park, Linggu Temple, East Beijing Road and Zhujiang Road, 12 sites in all. By measured the heavy metal contents in the two bryophytes and the environment, studied their ability of accumulating of heavy metals and the influence of environmental factors (the dust and the substrates), and preliminarily studied the sources of heavy metal contents of the epiphytic bryophytes. The main conclusions of this study can be summed up as follows:1) The abilities of accumulating heavy metals of the two epiphytic bryophytes are similar, and they changed together at different sample sites, which are at the highest level at the sites East Beijing Road and Zhujiang Road, next is Linggu Temple, the lowest is at the sites Zhongshan Botanical Garden, Zhongshan Tea-plantation and Qingliang Hill Park.2) The amount of air suspended particles contents of the two epiphytic bryophytes are much higher than that of the leaves of the trees which the epiphytic bryophytes attached to. And the ratio (contents of heavy metals in bryophytes/ contents of heavy metals in the corresponding leaves) is related to the content of TSP of every site. All heavy metal contents in Entodon compressus and its corresponding air suspended particles correlatives at high leave, next is Haplocladium microphyllum, and the correlation coefficients of the epiphytic bryophytes are much higher than that of the corresponding leaves. Then the results of Regressive analysis indicated that, air suspended particles influences the heavy metal contents of the epiphytic bryophytes.3) The difference of accumulation ability of heavy metals is significant between leaves and the bryophytes. The bryophytes'accumulation abilities are much stronger than that of the leaves, and the two bryophytes'accumulation abilities are similar.4) The elements in bryophytes and their corresponding substrate barks correlatives .By he results of Regressive analysis, the substrates barks influence the contents of elements Cr,Cu,Zn contents in Haplocladium microphyllum significantly(P﹤0.1), while to the elements Ni and Pb, the differences are not significant. To Entodon compressus, the substrates barks influence the contents of the 5 elements in Haplocladium microphyllum significantly(P﹤0.1).5) The heavy metal elements in different epiphytic Bryophytes come from different sources. When considering air suspended particles and substrate barks, The elements Cu,Ni,Pb and Zn in Haplocladium microphyllum are mainly from air suspended particles while the elements Cr from both air suspended particles and the substrates. The elements Cr,Cu and Ni in Entodon compressus are mainly from air suspended particles while the elements Pb and Zn from both air suspended particles and the substrates.