Mineralization Tests Made by Algae and It's Organic Matters

Key words: 
• biomineralizaftion by algae-bacterin /
• simulant tests /
• the channel and methods of biomineralization

Abstract: The experimental methods of accumulation metal and mineralization by algae-bacteria are introduced as follow: I.A artificial development on large scale algal mats have been carried out in Guan-rao saltwork,Shandong Province, from 1992-1996.According to last examination on December 2,1996,the thickness of algal mats come up 2.5cm. The sediment microzones with relating redox-gradient,which are developing in the algal mats,on the test pond floors have a strong influence for the mobilization and fixation of irons and sulfide.The precipitation of inorganic calcium carbonate(CaCO₃)and gypsum (CaSO₄)formed in the algal mats. As a result of the decay of organic matter in the black layer,an anaerobic microenviroment appears where hydrogen sulfide(H₂S) is produced by the activity of sulfate reducing bacteria. Organic matters from algal mats are divided into more than 335 compounds which could accumulate metal ions. Iron,which is bound on clay and other minerals,and which is dissolved also in the pore water,is in solution as Fe²⁺ underneath the black layer and precipitates as Fe³⁺,ferric oxide above the algal mats. In this higher productivity microenvironment of such an algal mat,the redox gradients are very high (more than 200mv Eh-difference between above and below the algal mat). Contents(‰) of some complex ions in the polysaccharide and protein from algal mats show that the Al,Ca,Fe,Mg, Sr,Zn in protein,are more than that in polysaccharide. Ⅱ.The tests of accumulating Au by algae,bacteria and fungi 1.Bacteria and Fungi Thiobacillus ferrooxiduns and Thiobacillus thiooxidans were separated from Tongling Au ore deposit.The results of culture experiment and test by X-ray-diffracterometer evidence that both generally existed in the mineral body,and from sulphate and H₂SO₄,changed the environment into acidity and the organic matters produced by bacteria decay could enrich the Au.The experiment made by Aspergillus niger also evidence the accumulation of Au. 2.The experimental results made by Lyngbya confercides,Spirulina platensis,Spirulina subsalsa of Cyanophyta and Chorella pyrenoidosa, Kirchneriate lunaris of Chlorophyat show that the activities of algal growth changed the blance of the ions systems CO₂-HCO^- ₃-CO^2- ₃ and Ca²⁺-Mg²⁺-Na⁺-PO^3-₄-Au²⁺,and,resulting in the rise of pH and the drop of Eh during growth stage.The Au contents accumulated by these algae are 3.7⁴-20.35⁴ times of cultural liquor concentrations,after growth for three weeks. 3.Algal action on formation and deposition of phosphates. The algae used in experiment are Spirulina platensis of Cyanophyta. (1)The OD value of algal growth was determined by a Model 721 spectrophoto-meter in 560nm wavelength. (2)The pH and Eh value of algal liquor was measured by a data acquisition system connected with a Model 251 glass electrode and a saturated calomal electrode was used for comparison.The surveying system consists of a sharp PC-1500A computer with a CE-printer and a 86-4D/A convertor. (3)The determination of the PO^3-₄ concentration was performed with a 721 spectrophotometer connected to computerized data acquisition system. (4)The tests of accumulation of phosphorus in algal cells were made by six 2L beakers,which were divided three groups.In group (1),the K₂HPO₄ concentration is 0.5g/L,in group (2) it is 1.5g/L,and in group (3)it is 2.5g/L. They were cultured under the onditional illumination of 2200LX.light/dark as 16/8h. (5)Phosphorus compounds (inorganic phosphate,ATP,ADP,polyphosphate containing phosphohexose,nucleotide and phosphate ester in algal cells)were extracted (as Liu Zhi-li et al,1996). (6)Mineralogical determinations were made with a D/MAX rotating anode X-ray diffracterometer. The results show that after the algal logarthmic growth stage,the pH Value rose From 8.323 to 9.027 (average value),the Eh dropped from 0.4259V to 0.2828V.Spirulina platensis could grow in the cultural liquor that contained PO^3-₄ ionic concentration up to 7.25g/L.After a growth cycle of the algae,the PO^3-₄ concentration in the cultural liquor dropped to an absolute value,0.9g/L,and white deposits of calcium magnesium phosphate ［Ca₂Mg(PO₄)₂.2H₂O］ and calcium sodium carbonates［Na₂Ca(CO₃) 2.5H₂O］ were separated from bottom of the bottles.The results of simulated test of mineralization show that under the normal atmospheric temperture and presure and in the Ca2+-HPO^2-₄-F-HCO₃ -H₂O system,the polyphosphate extracted from algal cels of Spirulina subsalsa may form mineral deposits which contain mainly carbonate fluorapatite,calcite and non-crystal phosphorus. Simulated tests of algae and ist organic matters actions on formatoin and deposition of the Cu,Mn,Zn etc.also show that algae and it's organic matter have important signification in the accumulation of metal ions.