Study On Soil Heavy Metal Contamination Features And Its Phytoremediation Of The Mining Area In Maguan County

Since the heavy metal pollution of soil is considered as an essential factor causingenvironmental destruction, this paper aims to explore soil pollution characteristics ofmining area as well as figure out the tolerance characteristics absorbing heavy metals ofplants. The mining area of Maguan County which is located in Wenshan Prefecture,Yunnan Province is chosen as researching sample. The study analyzes both soil heavymetal pollution of targeted area and distribution of heavy metals in local plants.Referring to data collection, we selected four different locations consisted of hillside,roadside and river banks of Flower stone and Tiansheng bridge. Due to the hillside areais polluted less comparing with other three, the paper uses plants collected from theslopes as control group. Five plants from mentioned locations are Eupatoriumadenophorum, Artemisia carvifolia, Bidens pilosa, Melastoma affine and Solanumxanthocarpum.Based on the analysis of data collected from sampling locations in terms of singlepollution index method and comprehensive evaluation, it is obvious that arsenic andcadmium pollute soil on the slope as well as Tiansheng Bridge significantly whilearsenic, copper, zinc and cadmium are the main factors of soil pollution on river bank ofFlower stone. In addition, cadmium and arsenic ranked as top two polluted componentswithin roadside spot respectively.Another finding is that there is distinguisheddifference on absorption of heavy metals among different plants though they areselected from same area. In general, the contents of heavy metal of plants indicatepositive relationship with that of soil. Furthermore, same plant presents differentabsorptive capacity when facing different heavy metals. Also, absorption ability of different parts of same plants in not identical. Basically, it follows the formula of soil＞root＞Stems and leaves.By analysing the bio-enrichment coefficients and migration coefficients of heavymetal elements in plants, we can conduct which plants perform huge tolerance to heavymetals and which plants are super enrichment plants. The rule is those which obtainenrichment coefficients and migration coefficient more than1could be defined asplants with super enrichment characteristics.(1) Arsenic: Comparing with other samples, Eupatorium adenophorumSpreng andarteannuin from hillside as well as arteannuin and Melastomacandidum from roadsidepresent higher enrichment and migration coefficients of arsenic. Especially forMelastomacandidum, with rate of0.5, its enrichment coefficient of stems and leavesdemonstrate much higher than others. Due to its strong absorptive capability of arsenic,it can be used for repairing polluted soil by road or improving arsenic-polluted soil inother cases. Another plant needs to be mentioned is Herbal BidentisPilosae. Though itsenrichment coefficient of arsenic is not strong, it presents higher migration coefficient.(2) Copper: With rate around one, artemisinin and yellow fruit tomato collected fromfour locations present bigger enrichment and migration coefficients to copper. Theirtolerance performs strongly. Since the enrichment and migration coefficients of yellowfruit tomato range from0.2-2and0.7-3respectively, it could contribute to soilreparation by transporting heavy metals from underground to superficial. Followedplant to solve copper pollution is artemisinin.(3) Zinc: All five sampling plants illustrate higher enrichment and migrationcoefficients to zinc and present absorptive and transporting capacity in a certain degree.Among them, Yellow fruit tomato,HerbaBidentisPilosae and Eupatorium adenophorumSpreng rank top three with the rate of more than one. Hence, they can be used as plantsfor improving Zinc-polluted soil.(4) Lead: It is observed that in5planting object, the concentration factor of the heavymetal lead is small, but the migration coefficient is relatively larger, basically close to1or more than1, for example in the melastoma candidum gathered around the TianShengBridge river, the migration coefficient reaches up to4.0405. From all above, it can beknown that the ability of the plant to concentrate lead is not strong, but the migrationspeed is very fast. Therefore, the melastoma candidum can be a potential plant spicy toimprove the polluted soil.(5) Cadmium: The average enrichment and migration coefficients of Cadmium inHerbaBidentisPilosae indicate highest. Samples from different locations obtain enrichment coefficient in different degree with the range from0.1to1.1while keep thesame standard in migration coefficient at high level of0.8to3. Thanks to the rate of twocoefficients being greater than1, HerbaBidentisPilosa shows strong absorptive andtransporting capacity which are recommended as main abilities to repaircadmium-polluted soli.