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Purpose <p>This study investigates the role of sediments in Yangzonghai Lake following engineered restoration efforts, with a focus on their functions in the context of post-remediation management. The stability of arsenic in these sediments is critical for the aquatic ecosystem and its biota. Through a multi-faceted approach, we aim to provide insights into the sediment dynamics after restoration.</p> Methods <p>The collected sediment samples were freeze-dried, and in situ dissolved organic matter (DOM) was extracted from the surface layer. The adsorption capacity of the sediments for exogenous arsenic was evaluated through a series of experiments, including adsorption isotherms, adsorption kinetics, and interference ion tests. The arsenic release capacity of the sediments was investigated using shaking experiments. Additionally, arsenic speciation analysis was conducted to assess the potential for arsenic release from the sediments.</p> Results <p>The maximum adsorption capacities of the sediments for arsenic were determined to be 2.26 mg g<sup>− 1</sup> for As(V) and 2.63 mg g<sup>− 1</sup> for As(III). Moreover, the sediments exhibit strong resistance to interference from common anions, indicating that they can act as a sink for arsenic adsorption in lakes. During the desorption experiments, arsenic release was detected exclusively in the presence of phosphate, with a relatively low release concentration of 6.31&#xa0;mg kg<sup>− 1</sup> dry-sediment, which accounted for only 3.03% of the total arsenic content in the sediment. In contrast, the presence of in situ DOM suppressed arsenic release, highlighting the complex role of environmental factors in arsenic mobility. Speciation analysis further revealed a clear temporal trend: the proportion of arsenic in the residual fraction increased from approximately 70% in 2014 to 85% in 2023, reflecting a significant shift towards more stable arsenic forms over time.</p> Conclusions <p>The sediments in Yangzonghai Lake primarily function as a sink for exogenous arsenic, demonstrating sustained adsorption capacity. Given the relatively stable environmental conditions of the lake, the potential for sediments to act as a source of arsenic release is minimal. These findings provide critical insights into the long-term stability and ecological risk of arsenic contamination in the lake ecosystem.</p>

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Sediments in Yangzonghai Lake after engineering treatment with ferric salt flocculation for arsenic mitigation: source or sink??

  • 期刊论文

  • 发表日期：

    2025年4月7日

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  • Boxian Ren,
  • Jinwei Wang,
  • Yaling Dai,
  • Chen He,
  • Shixiong Wang,
  • Xiangjun Yang,
  • Zhiguo Lin,
  • Conghai Zhang

摘要

Purpose

This study investigates the role of sediments in Yangzonghai Lake following engineered restoration efforts, with a focus on their functions in the context of post-remediation management. The stability of arsenic in these sediments is critical for the aquatic ecosystem and its biota. Through a multi-faceted approach, we aim to provide insights into the sediment dynamics after restoration.

Methods

The collected sediment samples were freeze-dried, and in situ dissolved organic matter (DOM) was extracted from the surface layer. The adsorption capacity of the sediments for exogenous arsenic was evaluated through a series of experiments, including adsorption isotherms, adsorption kinetics, and interference ion tests. The arsenic release capacity of the sediments was investigated using shaking experiments. Additionally, arsenic speciation analysis was conducted to assess the potential for arsenic release from the sediments.

Results

The maximum adsorption capacities of the sediments for arsenic were determined to be 2.26 mg g− 1 for As(V) and 2.63 mg g− 1 for As(III). Moreover, the sediments exhibit strong resistance to interference from common anions, indicating that they can act as a sink for arsenic adsorption in lakes. During the desorption experiments, arsenic release was detected exclusively in the presence of phosphate, with a relatively low release concentration of 6.31 mg kg− 1 dry-sediment, which accounted for only 3.03% of the total arsenic content in the sediment. In contrast, the presence of in situ DOM suppressed arsenic release, highlighting the complex role of environmental factors in arsenic mobility. Speciation analysis further revealed a clear temporal trend: the proportion of arsenic in the residual fraction increased from approximately 70% in 2014 to 85% in 2023, reflecting a significant shift towards more stable arsenic forms over time.

Conclusions

The sediments in Yangzonghai Lake primarily function as a sink for exogenous arsenic, demonstrating sustained adsorption capacity. Given the relatively stable environmental conditions of the lake, the potential for sediments to act as a source of arsenic release is minimal. These findings provide critical insights into the long-term stability and ecological risk of arsenic contamination in the lake ecosystem.