Effects of microcystin-LR on purification of drinking water source and physiological response of Hydrocharis dubia (Bl.) backer

Abstract

Abstract The safety of drinking water source directly affects human health. Ensuring the safety of drinking water is critical. Microcystin-LR (MC-LR), a toxic and common pollutant, releases by algae into drinking water source and can impede the in-situ remediation effect of aquatic plant on drinking water source purification. However, the effect mechanism of the MC-LR on the purification of the drinking water by aquatic plant remains unclear. This study aims to explore the effects mechanism of MC-LR (0–10 µg L− 1) on drinking water source purification by Hydrocharis dubia (Bl.) backer. After an exposure experiment, the removal rate of NH4+-N, TP, and COD promoted significantly at low concentrations of MC-LR (< 1µg L− 1). And the removal rate of NH4+-N, TP, and COD increased from 78.9–90.7%, 70.0–93.2%, and 46.0–77.3%, respectively. With the increase of MC-LR concentration, the pollutant removal rate was obviously inhibited causing by concentration-dependent. Furthermore, the growth and development of the Hydrocharis dubia (Bl.) backer roots were significantly promoted at the concentration of 0.2 µg L− 1. The length, tips, surface area, and average diameter of the root increased by 71.3%, 271.4%, 265.5%, and 113.0%, respectively. Chlorophyll contents under low-concentration MC-LR shows a 14.5%-15.7% promoting effect compared with the control group (CK). The activities of POD and CAT were also stimulated with the MC-LR increasing at low concentration. Notably, the MDA contents increased with increasing MC-LR concentration (p < 0.01). Therefore, the presence of MC-LR could affect the purification efficiency of Hydrocharis dubia (Bl.) backer in drinking water source. This study indicates the effect mechanism of MC-LR on drinking source water purification by Hydrocharis dubia (Bl.) backer.