Phytoextraction and Antioxidant Defense of Mangrove Seedling (Kandelia obovata) to Inorganic Arsenate Exposure

Guirong Wu,Caimei He,Sujuan Wang,Kang Mei,Liling Jiang

doi:10.3390/w14040643

Abstract

Increasing arsenic (As) pollution is posing potential endangerment to mangrove wetland ecosystems. Mangrove phytoextraction, translocation, and responses to As exposure must be urgently addressed. In this study, the growth and physiological response of Kandelia obovata seedlings were examined after addition of 25−200 mg kg−1 As under sediment culture conditions. Results showed that the seedling morphological variations were not significant below 100 mg kg−1 compared to the control group, indicating superoxide dismutase, peroxidase, and catalase synergetic interaction to resist the As exposure. High As concentrations (150–200 mg kg−1) inhibited the seedling growth accompanied by a significant increase in malondialdehyde content and decrease in activities of antioxidant enzymes. Toxicity symptoms and mortality appeared in 200 mg kg−1 As, presumably because the plant reached the limit of As tolerance. Besides, As accumulated mainly in roots, accounting for 87.04–97.85% of the total As, and the bioaccumulation factor (BCF) was >100%. However, the BCF and translocation factor (TF) in stems and leaves were below unity, illustrating a weak capacity of transferring As to aerial parts of the seedlings. Overall, K. obovata is a potential remediated species in polluted coastal wetlands due to high phytoextraction capacity and high tolerance to As exposure.

Highlights

IntroductionMangroves are evergreen, growing in tropical or subtropical coastal intertidal wetlands.As the main producers of estuaries and wetland ecosystems, mangroves play a critical role in preventing waves, reinforcing embankments, protecting benthic biodiversity, and maintaining the balance of mangrove ecosystems [1,2,3]
Mangroves are evergreen, growing in tropical or subtropical coastal intertidal wetlands.As the main producers of estuaries and wetland ecosystems, mangroves play a critical role in preventing waves, reinforcing embankments, protecting benthic biodiversity, and maintaining the balance of mangrove ecosystems [1,2,3]
25–100 mg kg−1 As concentration, no obvious difference in the height of seedlings was registered compared to the control (p > 0.05), while the height and biomass significantly reduced (p < 0.05) at As concentration of 150 mg kg−1

Summary

Introduction

Mangroves are evergreen, growing in tropical or subtropical coastal intertidal wetlands.As the main producers of estuaries and wetland ecosystems, mangroves play a critical role in preventing waves, reinforcing embankments, protecting benthic biodiversity, and maintaining the balance of mangrove ecosystems [1,2,3]. Mangroves are evergreen, growing in tropical or subtropical coastal intertidal wetlands. The mangrove systems have become the main repository of heavy metals because of their specific physico-chemical properties, such as a high content of sulfides, organic matter, and clay, which promotes the adsorption and precipitation of heavy metals in the sediments [6,7,8]. In the case of Pearl River port in Guangdong Province, China, from the Seventh Five-Year Plan Period (1986–1990) to 2018–2019, the content of As in the sediments increased from 8.9 to 52.08 mg kg−1 [9]. The As content in the intertidal plain and mangrove sediments of Shenzhen Bay was up to 152.4 and 199.66 mg kg−1 , respectively [10]

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Discussion

Conclusion