Utilization Potential Assessment Of Phosphorus In Different Minerals Based On Cyanobacteria Bloom In Shallow Lakes

Minerals in shallow lake sediments/suspensions are the main carriers of phosphorus in natural water bodies and play an important role in the phosphorus balance between sediments/particulates and algae.However,the availability of phosphorus loaded by different types of minerals is still unclear.In this study,typical minerals of lake sediments/suspensions,ferrihydrite,goethite,hematite,α-Al2O3,α-Al(OH)3,montmorillonite,kaolinite,hydroxyapatite,srengite(FePO4)and variscite(AlPO4)were selected to investigate the growth response characteristics of potential to different mineral-loaded phosphorus and to analyze the algal availability of phosphorus to algal.The main findings are as follows.The results of adsorption-desorption experiments on Fe/Al oxides showed that the quasi-secondary kinetic equations fitted better the kinetic process of phosphorus adsorption by Fe/Al oxides;the adsorption of phosphorus showed that ferrihydrite(28.82 mg/g)>goethite(5.76 mg/g)>α-Al2O3(3.99 mg/g)>αAl(OH)3(3.42 mg/g)>hematite(3.22 mg/g).The adsorption of phosphorus by Fe/Al oxides decreased with increasing pH and phosphorus adsorption by ferrihydrite and α-Al(OH)3 was particularly sensitive to pH changes.Desorption experiments with O.1mol/L NaOH on Fe/Al oxides loaded with phosphorus showed that the phosphorus desorption rate increased with increasing adsorption amount for iron oxides and decreased with increasing adsorption amount for aluminum oxides,and the phosphorus desorption rale of aluminum oxides decreased with the increase of adsorption amount,and the desorption capacity showed that:hematite>goethite>ferrihydrite,α-Al2O3>α-Al(OH)3.The potential of algae to utilize mineral phosphorus was studied using Microcystis aeruginosa and Anabaena flos-aquae,respectively,with different mineral loads of phosphorus as the sole source of phosphorus.The results showed that phosphorus in the chemically bonded state in both FePO4 and AIPO4 could not be utilized by the two algae,and the utilization of phosphorus in other different minerals ranged from 45%to 100%.The utilization potential of Fe/Al oxides for phosphorus adsorption is opposite to their ability to adsorb phosphorus,and the utilization efficiency of Microcystis aeruginosa/Anabaena flos-aquae was in the order of hematite(99.42%/85.66%)α-Al2O3(93.18%/78.69%)>α-Al(OH)3(74.63%/63.90%)>goethite(72.53%/58.07%)>ferrihydrite(66.11%/46.82%).The utilization of phosphorus on the surface of clay minerals and hydroxyapatite that can be desorbed by 0.1 mol/L NaOH was:kaolinite(81.93%/74.28%),montmorillonite(98.43%/73.33%),and hydroxyapatite(74.04%/66.43%).In addition to the promotion or inhibition of algal growth by the minerals themselves,there was a difference in the potential of the two algae to utilize the mineral phosphorus.The phosphorus utilization efficiency of the Microcystis aeruginosa group was about 15%higher than that of Anabaena flos-aquae due to the difference in pH during the algal culture.The adsorption structure of phosphorus on mineral surfaces can explain the ability of algae to utilize phosphorus,so the ecological effects of phosphorus in sediment/suspension in shallow lakes should be evaluated with full consideration of the effects of phosphorus regulation by different minerals and environmental conditions.Figure [51] Table [6] Refermce [101]...