Studies Of The Purification Effect Of Plants On Sewage Containing Mn And The Selection Of Dominant Plants Species

12 kinds of wetland plant species which were aqua-cultured in order to test theirpurification ability of sewage containing Mn, and to study the dominant plant speciesCanna indica and Arachnis labrosa (Lindl.) Rchb. F which have better comprehensiveprocessing results, efficient manganese accumulation ability, greater growth capacity,better landscape. A study on the mechanism of plant resistance against heavy metals wasconducted with the aim of providing theoretical basis of Mn polluted water plantstreatment. The main results are as follows:1 The tested plants decreased the pH value of sewage, the longer the wastewaterremains the more obviously the removal rates of sewage pollutants of CODcr. TN. TP andMn.Canna indica,Calla palustris Linn.,Crinum latifolium Linn., Arachnis labrosa (Lindl.)Rchb. F were most effective at integrated removing.2 The tested plants significantly absorbed and transported Mn。The accumulation ofMn was mainly done in the roots and the leaves. The Mn content in Polygonumlapathifolium Linn, Canna glauca L and Canna indica Linn leaves were significantlyhigher than those in the roots, and reached 2100-2800 mg/kg. Canna indica Linn,Polygonum lapathifolium Linn, Arachnis labrosa (Lindl.) Rchb. F and Crinum latifoliumLinn etc…could be the prior choice species for constructed wetland phyto-remediationof low concentration Mn polluted water.3 Under different Mn treatments, the sewage purification ability of wetland plants were as follows: Low concentration of Mn (0-50 mg/L) promoted the CODcr and TNremoving ability of the tested plants. Along with the increase of Mn concentration andtime of treatment, there were significant decrease of CODcr and TN removing rate.There wasn't great effect of plant TP purification below 500 mg/L Mn stress. Higher isthe Mn treatment concentration, lower is the rate of Mn removing from polluted waterby plants.4 Treatments with 15-50 mg/L Mn inhibited shoot and root nitrogen absorption ofCanna indica Linn but promoted its shoot phosphorus accumulation and transportability from the shoot to the root. Under Mn stress, the shoot nitrogen content ofArachnis labrosa (Lindl.) Rchb. F were higher than those in the control but its shootphosphorus absorption were inhibited at different levels. Treatment with 15 mg/L Mnand 500 mg/L Mn caused a certain increase in the nitrogen content of Arachnis labrosa(Lindl.) Rchb. F root and the treatment with 15 mg/L Mn also can enhance thephosphorus accumulation in the shoot.5 Canna indica Linn and Arachnis labrosa (Lindl.) Rchb. F had a strong tolerranceand absorption capacity of manganese: the content of manganese in both plants and thetotal amount of manganese transfer to their shoot increased linearly with the increase ofthe manganese concentration of the treatment.6 Treatments with manganese concentration below 50 mg/L, increased at differentlevels the leaf chlorophyll content, the soluble sugar content, SOD and POD activities inCanna indica Linn and Arachnis labrosa (Lindl.) Rchb. F. Whereas, with the increaseof the treatment manganese concentration, restraining effects occurred and leaf MDAcontent increased along with the increase of treatment manganese concentration.