報告書番号

U00022

タイトル（和文）

植物による環境修復(1) -－現状と遺伝子工学の適用に関する調査－-

タイトル（英文）

The current status of phytoremediation - a problem in the technology and the applicability -

概要 （図表や脚注は「報告書全文」に掲載しております）

約330編の論文を調査し、ファイトリメディエーション技術の現状について以下の点を明らかにした。①対象となった汚染物質：重金属類についてはほとんどの種類が網羅されているが、化合物では富栄養化物質と有機塩素系化合物や爆薬類以外には報告が少ない。また、セシウムなどの放射性物質も報告がある。②用いられた植物：500種類以上の既存種が検討された中で、重金属ではアブラナ科植物、化合物や放射性物質についてはブタクサ等が高い能力を持つとされている。③処理に要する時間とコスト、市場規模：全般に既存の植物は汚染物質の吸収効率が低く、処理に時間がかかる。一方、既存の処理法とのコスト比較では概ね1/10以下と試算されている。また、市場は今後も大きく拡大すると予測されている。さらに、遺伝子工学を応用したリメディエーション用植物の育種について、今後利用される可能性の高い遺伝形質を抜粋し、対象物質毎にまとめた。

概要 （英文）

Phytoremediation is a technique to restore the environment using living plant itself. The concept is closed up in the last decade since the strategy based on the low energy input and low waste output is necessary for the sustainable development of our society. In this paper, we reviewed 330 references and cleared the status in quo from the view of technology and the applicability. The points of discussion are as shown in below:1. What kind of pollutants are cleaned by phytoremediation?The main course of the phytoremediation is aimed for a kind of heavy metals. Most of the metal species are covered to restore (ex. Cd, Pb, Ni, Hg, Zn, Se, Cr, As, Al, Mn etc.). On the other hand, chemicals excepting organic civil waste, chlorinated organic compounds and explosives are not on the target. Interestingly, kind of radionuclides, such as Cs and Sr, dispersed into the surroundings by the accident of Chernobyl, are also well studied to restore by plant.2. What kind of plant is used for phytoremediation?Even several hundreds of plant species are valuable to accumulate heavy metals, it can be concluded that a kind of Brassica spp. (e.g. Indian mustard) is one of the most useful plant to restore metals from polluted soils. However, it is reported that only a few species like Cyperus esculentus can catalyze TNT (trinitrotoluene) and RDX (hexahydro-1,3,5-triazine), even though the metabolites are still toxic. It may be caused from the mechanisms of tolerance in plants against chemicals that are not based on the disintegration but on the separation and/or modification. In addition, a radionuclide accumulator is not identified so much other than a few species like Chenopodiaceae spp.3. How about the applicablity and the market size of phytoremediation are?The potential applicability and the market size of the phytoremediation might well. However, it can not be estimated precisely, because the technique is still under developing. At least, we can see the advantage in the case that the pollution is dispersed in large area at low concentration and/or the cost is compared with the other restoration techniques. One estimation about the market size showed that it will be greater than 214 million dollars until 2005. 4. The probability for creation of new plant using the recombinant technology for phytoremediationWe also reviewed the aspects to use recombinant technology. It will make the phytoremediation technique to be more advanced and sophisticated restoration tool of the environmental problem. Actually, some of the possibilities have already examined (e.g. Mercury uptake and vapor plant and TNT completely catalyze plant). The probable genetic traits now on concerning are listed with the explanatory notes.

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