Effects of phosphate on the toxicity and bioaccumulation of arsenate in marine diatom Skeletonema costatum

Qunhuan Ma; Lizhao Chen; Li Zhang

doi:10.1016/j.scitotenv.2022.159566

Effects of phosphate on the toxicity and bioaccumulation of arsenate in marine diatom Skeletonema costatum

Sci Total Environ. 2023 Jan 20;857(Pt 2):159566. doi: 10.1016/j.scitotenv.2022.159566. Epub 2022 Oct 18.

Authors

Qunhuan Ma¹, Lizhao Chen², Li Zhang³

Affiliations

¹ Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China; University of Chinese Academy of Sciences, Beijing 100049, China.
² Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China; Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou 511458, China.
³ Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China; Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou 511458, China; Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, China. Electronic address: zhangli@scsio.ac.cn.

PMID: 36265640
DOI: 10.1016/j.scitotenv.2022.159566

Abstract

The effects of nutrient phosphate (P) at environmentally relevant levels on the toxicity of arsenic (As) in marine microalgae have been rarely known. In the present study, we explored the toxicity and bioaccumulation of As in a globally distributed diatom species Skeletonema costatum at different ambient P concentrations. The results showed that As toxicity was suppressed at elevated P concentrations. Intracellular As content ([As]_intra) and the molar ratio of intracellular As to P ([As:P]) were negatively correlated with the ambient P concentrations. The trends of As bioaccumulation were substantially different between the relatively low (0, 0.5 and 1.5 μM) and high P concentrations (7.5 and 37.5 μM). Both [As]_intra and [As:P] suggested that As bioaccumulation was a better factor to explain the As toxicity comparing to the ambient As concentration. The 4 h As uptake kinetics at different P concentrations followed Michaelis-Menten kinetic pattern. The maximum uptake rates (V_max) decreased with the increase in P concentrations, and the half-saturation constants (K_d) remained constant except for that at extremely high P concentration (37.5 μM-P), suggesting the depression of P on As uptake was mainly due to the non-competitive effect. Overall, these results demonstrate that the P concentration in seawater is an important factor affecting As toxicity and bioaccumulation in the marine diatom. This study therefore helps us better understand the effects of eutrophication on the toxicity and biogeochemistry of As in the marine environment.

Keywords: Arsenic; Diatom; Phosphate; Toxicity; Uptake kinetics.

MeSH terms

Arsenates / toxicity
Bioaccumulation
Diatoms*
Phosphates

Substances

arsenic acid
Arsenates
Phosphates