Keywords: 
• trace element zinc /
• organic phosphorus /
• inorganic phosphorus /
• Microcystis aeruginosa /
• microcystin

Abstract: Focusing on the effect of phosphorus and trace elements on the growth of algae, the effects of zinc on the growth and toxicity of algae cells under different phosphorus sources were studied. Taking Microcystis aeruginosa as the algae species and selecting inorganic phosphorus potassium hydrogen phosphate (K₂HPO₄), small molecule organic phosphorus glycerin sodium phosphate (NaGly) and macromolecular organic phosphorus lecithin (LEC) as the source of phosphorus, the effects of different zinc (Zn²⁺) concentration on algal cell density, alkaline phosphatase activity (APA) and intracellular microcystins (MC-LR) were studied. It was found that the effect of trace element zinc on algal cell growth was significant using NaGly as the phosphorus resource, while it had no significant effect on the growth of algal cells when K₂HPO₄ or LEC was used as the phosphorus resource. APA was not only related to the phosphorus source but also related to zinc content. When LEC was used as phosphorus source, the APA was significantly higher than that of K₂HPO₄ or NaGly. It also showed the lower the zinc content, the lower the APA. While the lower the content of zinc with K₂HPO₄ as the phosphorus resource, the APA was higher. The content of zinc had little effect on the APA when NaGly was the phosphorus source. Phosphorus and trace element zinc had an impact on the production of algal cells. NaGly was beneficial to the production of microcystin. On the opposite, LEC inhibited the microcystin production of algal cells and the lower the zinc content, the more microcystin the algal cells produced. In summary, phosphorus source and trace element zinc jointly had an impact on the growth and toxin production of algal cells. Small molecular organic phosphorus and zinc had significant effects on the growth and toxicity of algal cells especially.