Research Of Heavy Metal Transfer & Accumulation In Coniferous Forest Rock-earth-plant System

Chengdu Economic Zone, including Chengdu, Deyang, Mianyang, Meishan, Ziyang, Leshan, Yaan City and other eastern regions, is the typical economically active circle where ecological problems such as point source pollution and vegetation degradation caused by industrialization, urbanization and population aggregation is increasingly prominent. This paper is to clarify that the mechanism of pollution in the area, effect of phytoremediation and plant structure adjustment is the ke y of relieving environmental degradation–industry development conflicts.Based on the results of "Chengdu Economic Zone multi-purpose geochemical survey" and "Chengdu Economic Assessment of Forestry Ecological geochemistry", the research of Heavy Metal Transfer & Accumulation in Coniferous Forest Rock-Earth- Plant System on the main types of coniferous tree species: Pinusmassoniana, Cryptomeria fortunei, Cunninghamia lanceolat, and the basic geochemical data and the current technical information, this paper finds out the characteristics of migration and accumulation of the geochemical elements from the starting point (source) - the end (the destination) and the toxic and harmful elements fractionation on different organs of various species of geological rock mass (Soil parent rocks)- Soil (layers-bit) - plant (the organ) scale systems through the combination of the ecological survey and forest ecological survey of the differential coniferous trees in Economic Area. Explore the mechanism of conifer species and soil variables'interaction from respects of ecological geochemistry and agricultural geology; clarify the nature and content of tree species and soil interface interaction; and offer decision making foundation for anti-pollution barriers through the eco-geochemical overall assessment.1)The soil geologic potential input sequence of the 3 coniferous forests Site As, Hg elements of rock library weathering is: Cunninghamia lanceolata, Pinusmassoniana, Cryptomeria fortunei; Al,Pb,Cd element rock weathering on soil geological repository, among which the highest potential input is Cryptomeria fortunei. 2)Although Al2O3,As of Pinusmassoniana soil surface soil are both lower than the Chengdu economic region, the background value in China, Cd,Hg,Pb are higher, with characterizations of different levels of soil contamination. Cryptomeria fortunei soil's Al2O3 is lower than the background value in China but higher than the Chengdu economic region, As is lower than the background value in China but higher than the Chengdu economic region; Cunninghamia lanceolata soil's Al2O3,As are both lower than the Chengdu economic region, the background value in China, Cd,Hg,Pb are higher than he background value in China but lower than the Chengdu economic region.3) As for the five elements in coniferous soil heavy metals, except Al, As,Hg,Cd,Pb show a trend of accumulation in the soil surface, especially the Pinusmassoniana soil, are not only entirely different, but also far from the mean level.4) Cryptomeria fortunei's enrichment trend: Pb>Hg>Cd>Al>As ;Pinusmassoniana's enrichment trend: Pb>Cd>Hg> Al>As; Cunninghamia lanceolata's enrichment trend: Pb>Cd>Hg >Al>As. Comprehensively, the three conifer species have a high accumulation ability on Pb, Hg, Cd, but low on Al,As. Measurement of the enrichment factor of three conifer species shows: Organ leaf, one of the conifers, has stronger regeneration capability, strong enrichment of branches growth in one year, aging organs such as trunk are comparatively weak. Remediation of Heavy Metal's overall trend is: Cryptomeria fortunei, Pinusmassoniana, Cunninghamia lanceolata.5) As's displacement coefficient sequence in all plants is: Pinusmassoniana, Cunninghamia lanceolata, Cryptomeria fortunei. Hg's size of sequence is: Cryptomeria fortunei,, Cunninghamia lanceolata, Pinusmassoniana. As for Pb, the sequence is: Cunninghamia lanceolata,Pinusmassoniana, Cryptomeria fortunei. A1's displacement coefficient sequence is: Cryptomeria fortunei, Cunninghamia lanceolata, Pinusmassoniana. Cd's displacement coefficient sequence is: Cunninghamia lanceolata, Pinusmassoniana, Cryptomeria fortunei. Seen for the above, As has strong ability of displacement in Pinusmassoniana and Cunninghamia lanceolata. Hg is apt to displace in Cryptomeria fortunei. Al has high transport capacity in Cunninghamia lanceolata and Cryptomeria fortunei. Pb has high migration ability in Pinusmassoniana and Cunninghamia lanceolata. Cd is apt to displacement in Pinusmassoniana.6) Pinusmassoniana, Cunninghamia lanceolata and Cryptomeria fortunei have a similar law on the absorption of toxic elements on the five stocks. Their high concentration of plant organs are the root sand leaves that of high regeneration ability; tree trunks, branches and bark that of relatively low accumulation capacity; Cryptomeria fortunei is the low absorption of Pb element species.Through the research on the element transfer and transform of As, Hg, Al, Cd, Pb elements in the coniferous forest to rock, soil and trees of Chengdu Economic Zone, the paper clarifies the heavy metals distribution patterns; the basic law of accumulation and mechanism of migration, concomitance and accumulation in rock - soil - plant ecosystem, and provides technical mechanism for screening of phytoremediation anti-pollution of the target species, construction of forests with forest type barriers and stratified forest management model.