The Influence Of Cation And A Anion In Soil On Phytoliths Of Phragmites Australis In Northeast China

Phragmites australis and relevant soil are sampled from twelve sample plots in Northeast China. And then we tested the exchange capacity of selected cation and anion(Cl^-, NO₃^-, SO₄^2-, K⁺, Ca²⁺, Na⁺ and Mg²⁺) to explore the spatial and temporal differentiation rules of cation and anion and their influences on phytolith. This work is significant for phytolith study. And the results will provide basic references for wetland management and paleovegetation reconstruction. The main results are as followings.The mean exchange capacity of chloridion, nitrate ion and sulfate ion is 292.67 mg·kg^-1, 297.14 mg·kg^-1 and 367.49 mg·kg^-1. And the mean exchange capacity of potassium ion, calcium ion, sodion and magnesium ion is 80.30 mg·kg^-1, 91.07 mg·kg^-1, 281.51 mg·kg^-1 and 37.63 mg·kg^-1. Obviously, the ion exchange capacity distribution characteristic is not only affected by soil parent material and physical and chemical property of different soil. But also it’s controlled by the hydrothermal condition of the sample plot. However, it changes as the growing demand of P. australisand hydrothermal condition varies at different growing period.Ion exchange capacity distribution characteristic of potassium ion and sodion, calcium ion and magnesium ion is similar. But sodion and potassium ion has a significant impact on conductivity, while the calcium ion and magnesium ion have a correlation with sulfate ion. Variation coefficient analysis shows cation exchange capacity of soil and P. australis changes obviously as the time varies. But the vary trend among different ions is different.Ion content in P. australis is influenced by the ion exchange capacity in soil and its own demands. The content of nitrate ion, sulfate ion, calcium ion, sodion, magnesium ion in P. australis has a remarkable correlation with their exchange capacity in soil. And also, the ratio of anion to cation in P. australis is much lower than that in soil. So we may speculate P. australis absorbing these ions passively. However, the content of chlorion and potassium ion in P. australis didn’t show any remarkable correlation with the ion exchange capacity in soil. And the ratio of anion to cation in P. australis is higher than that in soil. So we think P. australis absorbs these two ions via an active absorption process.The concentration of phytolith in P. australis has a correlation with the exchange capacity of nitrate ion, sulfate ion, calcium ion, sodion and potassium ion. Detrended Correspondence Analysis（DCA） results show the concentration of phytolith in P. australis is mainly affected by the exchange capacity of calcium ion, potassium ion and sulfate ion in soil.