Transformation Of Biotite Into Vermiculite By Bacillus Mucilaginosus YM-1 Or Aspergillus Aculeatus HR-1

Biotite weathering is one of the important surface geochemistry process.Studying biotite weathering can provide important clues for elucidating a series of scientific problems including soil processes and nutrient cycling.Most researchers main focus on the elements release rates in microbially assisted dissolution of biotiteIts weathering was studied using Bacillus mucilagnsus(YM-1)days and Aspergillus aculeatus(HR-1)in batch reactors.The solid products were analyzed by X ray diffraction technique(XRD)and electron microscopy.Dissolution was monitored by inductively coupled plasma optical emission spectrometry(ICP-OES)analysis of elements(Al,Fe,K,Mg,and Si)released into the leach solution;the low molecular weight organic acidsconcentrationswere monitored by high performance liquid chromate graphy(HPLC).The contradistinctive research of the rate and order of dissolution rate and sequence of major elements in the weathering process of black mica by bacteria and fungi were studied.A preliminary analysis of the weathering of the whole black mica was carried out in the experiment system.Special use sedimentation centrifugal method of solid products in the clay fraction were systematically,in order to find out the actual evidence of the existance of the secondary minerals,and we also hope to provide a kind of effective method.Our results show that:(1)In comparison to the control experiment,YM-1 and HR-1 can significantly accelerate the biotite weathering.Dissolution rate of biotite in Aspergillus aculeatus experiment was about 65 times than in Bacillus mucilaginosus experiment.(2)According to the apparent dissolution ability of the cations in the solution,the roughly order of elemental dissolution from biotite in YM-1 or HR-1 erpriment are:the interlayer(k)>the octahedral(Fe,Mg,Al)>the tetrahedrals(Al,Si).(3)Microorganism accelerated dissolution of biotite mainly by the acidification of the bulk liquid by organic acids.(4)Vermiculite layer percentage of interstratified biotite/vermiculite was from 23%(70 day)to 75%(180 day)in YM-1 experimental and from 23%(45 day)to 31%(90 day)in YM-lexperimental.The control experiments showed that,until the end of the experiment(180 day),there was no peak in X-ray diffraction pattern.This fully show that the strain YM-1 can accelerated biotite wether to vermiculite,and interstratified biotite/vermiculite was a intermediate product of biotite transform to vermiculite.(5)Diffraction peak of hydrobiotite was only found in<2?n solid phase products in YM-1/HR-1 experiment.HR-TEM results showed that hydrobiotite;was mainly found on the edge of the solid products in YM-1,and the K content of the edge was less.The results also show that,biotite weathering give priority to the edge of small size biotite.(6)We also found low crystallinity carbonate mineral particles in YM-1 experiment.This shows that bacteria is not only conducive to biotite weathering,but also conducive to the formation of carbonate minerals.