热带海洋学报 ›› 2023, Vol. 42 ›› Issue (5): 45-55.doi: 10.11978/2022236CSTR: 32234.14.2022236

• 海洋化学 • 上一篇    下一篇

滨海酸性硫酸盐土壤湿地沉积物中还原性无机硫和活性铁的耦合特性及环境意义

陈波1,2(), 覃子东1, 王锋1,2, 蔡平雄1,2, 张生银3   

  1. 1. 北部湾大学石油与化工学院, 广西 钦州 535000
    2. 广西绿色化工新材料与安全技术重点实验室, 广西 钦州 535000
    3. 中国科学院西北生态环境资源研究院, 甘肃 兰州 730000
  • 收稿日期:2022-11-07 修回日期:2023-01-17 出版日期:2023-09-10 发布日期:2023-02-22
  • 作者简介:

    陈波(1985—), 男, 博士, 副教授, 主要从事环境矿物学研究。email:

  • 基金资助:
    广西自然科学基金项目(2020GXNSFBA297128); 广西科技基地和人才专项(桂科AD20238041); 广西自然科学基金联合培育项目(2019GXNSFAA245016)

Coupling characteristics of reduced inorganic sulfur and reactive iron in coastal acidic sulfate soil wetland and its environmental significance

CHEN Bo1,2(), QIN Zidong1, WANG Feng1,2, CAI Pingxiong1,2, ZHANG Shengyin3   

  1. 1. College of Petroleum and Chemical Engineering, Beibu Gulf University, Qinzhou 535000, China
    2. Guangxi Key Laboratory of Green Chemical Materials and Safety Technology, Qinzhou 535000, China
    3. Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
  • Received:2022-11-07 Revised:2023-01-17 Online:2023-09-10 Published:2023-02-22
  • Supported by:
    Guangxi Natural Science Foundation(2020GXNSFBA297128); Special Talent Project of Guangxi Science and Technology Base(Guike AD20238041); Cultivation Project Jointly funded by Guangxi Natural Science Foundation(2019GXNSFAA245016)

摘要:

滨海酸性硫酸盐土成土母质中富含还原性硫化物(reducing inorganic sulfur, RIS)和活性铁等生源要素, 耦合制约着铁、硫以及重金属元素的环境地球化学行为。为了揭示滨海酸性硫酸盐土壤湿地沉积物中RIS和活性铁的耦合机制及环境意义, 文章通过在钦江河口滨海酸性硫酸盐土壤湿地采集深约40cm的沉积柱状样, 在垂向上对酸性可挥发硫(acid volatile sulfide, AVS)、黄铁矿硫(chromium reducible sulfur, CRS)、元素硫(elemental sulfur, ES)和活性铁[(Fe(Ⅱ)和 Fe(Ⅲ)]的含量和分布规律进行了厘定, 并结合沉积物的理化性质进行探讨分析。结果表明: 钦江河口酸性硫酸土中的活性铁中以Fe(Ⅲ)为主, 活性铁中的Fe(Ⅱ)和Fe(Ⅲ)在环境容易发生相互转换, 氧化还原电位(Eh)越低、有机质(organic matter, OM)含量越高越利于Fe(Ⅲ)还原为Fe(Ⅱ); 还原性无机硫以CRS为主, 其次为AVS以及少量ES, 成岩过程中还原性无机硫会相互转化, 其过程主要受到活性铁和OM控制, 但研究区还原性无机硫形成的限制因素并非活性铁, 而是OM的含量及活性; 较高的OM和Fe(Ⅱ)易造成AVS富集, 较高的Fe(Ⅲ)和Eh值利于ES生成, CRS除受OM和活性铁的控制, 还受到AVS转化率的影响; 研究区大部分样点的CRS/AVS比值较低, 表明AVS不能有效的转化为CRS, 硫化物活性与生物有效性较高。因此应尽量避免外源OM引入和人为活动扰动, 以免造成还原性无机硫氧化释放出H+形成酸害, 同时降低吸附或共沉淀在还原性无机硫上的重金属等污染物的浸出, 以减少环境破坏。

关键词: 酸性硫酸盐土湿地, 还原性无机硫, 活性铁, 矿化度

Abstract:

The parent materials of acidic sulfate soils in coastal areas are rich in reduced sulfides (reduced inorganic sulfur, RIS) and reactive iron, which jointly control the environmental geochemical behaviors of iron, sulfur and heavy metal elements. For purpose of revealing the coupling mechanism and environmental significance of RIS and reactive iron in coastal acid sulfate soils wetland, this study collected a sediment core with a depth of about 40 cm at the Qinjiang river estuary. The contents and distribution of acid volatile sulfur (AVS), chromium reducible sulfur (CRS), elemental sulfur (ES) and reactive iron (Fe(Ⅱ) and Fe(Ⅲ)) were investigated. The results show that Fe(Ⅲ) is the main reactive iron in the acid sulfate soil of Qinjiang river estuary, and Fe (Ⅱ) and Fe (Ⅲ) in active iron are easily interconverted in the environment. The lower the REDOX potential (Eh) and the higher the content of Organic Matter (OM), the more beneficial the reduction of Fe (Ⅲ) to Fe (Ⅱ). The reducing inorganic sulfur is mainly CRS, followed by AVS and a small amount of ES. In the diagenetic process, the reducing inorganic sulfur will convert to each other, and the process is mainly controlled by active iron and OM, but the limiting factors of reducing inorganic sulfur formation are the content and activity of organic matter. Higher organic matter and Fe (Ⅱ) are more likely to lead to enrichment of AVS, and higher Fe (Ⅲ) and Eh values are more conducive to the formation of ES.CRS is not only controlled by organic matter and active iron, but also affected by AVS conversion rate. The CRS/AVS ratio of most samples in the study area was low, indicating that AVS could not be effectively converted into CRS, and the activity and bioavailability of sulfide were high. Therefore, the introduction of exogenous organic matter and human disturbance should be minimized to avoid the release of H+ from reductive inorganic sulfur oxidation to form acid damage, resulting in the leaching of heavy metals adsorbed or co-precipitation on inorganic sulfur.

Key words: acid sulfate soil wetland, reducing inorganic sulfur, active iron, mineralization degree