Interaction of microalgae, nitrogen and arsenic in a water environment co-polluted by nitrogen and arsenic: current knowledge and future perspectives

Nitrogen (N) and arsenic (As) pollution in water environment seriously threaten human life and health. In order to improve the efficiency of sustainable remediation of N and As co-polluted water environment, the migration and transformation of microalgae, N, and As and their interaction were studied. Based on the bibliometric analysis and the research status of remediation for N and As co-polluted water environment, this study focused on the oxidation, reduction, methylation, and absorption of As by microalgae, analyzed the effects of N sources on the physiological and biochemical functions of microalgae, extracellular secretions, and cell growth, and revealed the mechanism of As enrichment by microalgae in the presence of N sources. It was found that the physiological and biochemical characteristics of microalgae showed complex changes under the condition of coexistence of N and As. N sources affect the metabolic pathways and key enzyme activities of microalgae, and affect the absorption and transformation of As. The extracellular secretions of microalgae may also change, and the organic acids and polysaccharides contained in them can be complexed with As, affecting the migration and bioavailability of As. The concentration of N and As and the type of N source affect the growth rate and cell morphology of microalgae. Under the appropriate concentration ratio of N and As, microalgae can adjust their physiological state to achieve the balance between growth and pollutant removal. Clarifying the physiological and biochemical change mechanism of microalgae under the coexistence of N and As and optimizing their ability to remove pollutants are the key to future research. This study can provide new ideas and references for the simultaneous purification of pollutants such as N and As in water environment.