| Huainan with a 100-year coal-mining history is an important coal-production base of the country in East China.The exploitation and utilization of coal resources has promoted the city economic and social development, however, at the same time it has also inspired a series of questions including geological environment and ecological environment problems for natural rock, water, and soil, for example large amount of coal gangue heaping, formation of subsidence areas, and so on.Using coal gangue to fill subsidence areas has been for several decades at Huainan mining area. Soil reconstruction factors were not considered in the traditional reclamation technology, which made great changes of soil physicochemical property physical structure and soil environment in the reclamation area. Meanwhile, the soil pollution problem of heavy metals was always an important and difficult point for study of mining area reclamation, which was produced by using coal gangue to fill subsidence areas. Because phytoremediation has a lot of advantage in soils remediation polluted to heavy metals, such as low cost, not destroying the soil structure, play a certain role to beautify the environment, and easily be accepted for the society, and so on. Nowadays, it has been focal problem of science and frontier field of research at home and abroad, especially Screening out and utilization of hyperaccumulators from the resources of farmland weeds.But for a long time, it is short of the studies about the physicochemical property of reclamation soil filled with coal gangue in coal mining area, the characteristics of heavy metals pollution, the transformation law of heavy metals in soil-plant system, and the systemic research of potentiality of phytoremediation for heavy metals with farmland weeds.Systematically summarized the development of research at home and abroad on the phytoremediation of heavy metal pollution in reclamation soil, this paper focuses on the following three research works:1. Research on characters of reclamation soil and coal gangueCombined with the field measurement and laboratory tests, the reclaimed soil and the coal gangue characters were relatively systematically researched, soil character of the filled reclaimed soil and the change of level were analyses. The results show that compared with characters of comparative soil, the moisture content, organic matter, rapidly-available potassium, rapidly-available phosphorus and total nitrogen in the soil of Panyi reclamation area were relatively low; both the amount of organic matter and rapidly-available phosphorus of the soil nutrient in Panyi reclamation area were relatively lacking, especially the organic matter amounts were in a famine level. By analyzing the characters of coal gangue that was used to filling the reclamation, the results indicated that the nutrient amounts of coal gangue after weathering were relatively rich, which could satisfy the need of plants' growth. But the saltness was relatively high, which might cause the salinization of the soil between the contact layers.2. Research on heavy metal pollution characteristics of reclamation soilTo collect 140 soil samples on the different layers of research area locale, these 9 heavy metals' space distribution characters of both vertical and horizontal—Cu, Cr, Mn, Zn, Ni, Pb, Cd, Hg and As in the reclamation soil were detailedly researched, and the surfer8.0 software was utilized to show a visualization express for the horizontal distribution of these heavy metals. The results indicated that there was some heavy metals risk of reclamation soil which comes from using coal gangue to fill the subsidence areas, and there was also some extend and scope of heavy metals pollution caused by accumulation of coal gangue hills and the existence of coal ash storage yard. And on the basis of these problems, some related researches on the heavy metals and the relevance between the soil heavy metal contents and the soil characters were conducted.3. Research on phytoremediation potential of farmland weedsBased on the 12 kinds of dominant farmland weeds of Panyi reclamation area as the research objects, the absorption and accumulation characters of these 9 heavy metals of the farmland weeds were analyzed, and then combined with Enrichment coefficient and translocation factor to screen out the heavy metals phytoremediation potential of these 12 kinds of dominant weeds. By referring to the screening standards of hyperaccumulator, Zn was accumulated by wild Vigna vexillata, Cd was accumulated by Erigeron annuus and Helianthus tuberosus. Hg was accumulated by Erigeron annuus, Bidens pilosa, Solidago canadensis, Aster subulatus and Vigna vexillata with two basic characteristics of hyperaccumulator.But the heavy metal amounts of the overground tissue which come from 6 kinds of compositae didn't reach to the critical content standards of hyperaccumulator, so the hyperaccumulator of heavy metal had been not screened out.Figure [20] table [19] reference [53]... |
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