A simple and rapid method for measuring total free sulfides in marine sediments

IF 2.1 3区 地球科学 Q2 LIMNOLOGY
Peter J. Cranford
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引用次数: 0

Abstract

The quantitatively most important process by which organic matter in marine sediments is mineralized is performed by sulfate-reducing bacteria, resulting in the accumulation of total dissolved (free) sulfide (S2− = H2S + HS + S2−) in porewater. S2− is toxic to benthic animals and vascular plants and measurements serve as a proxy for the deleterious effects of organic enrichment on benthic habitat, biodiversity, and ecosystem function. Methodologies for measuring S2− in water have been pursued for at least a century, and standard approaches employ colorimetry (methylene blue and iodometric titration) and potentiometry. These standard methods require between 1 and 200 mL of porewater, which can be laborious to obtain. The ion-selective electrode method is widely employed as a practical approach for sediment S2− analysis but lacks analytical robustness and is highly prone to measurement biases that misinform research and environmental management decisions. A technically simple method is described, based on direct UV spectrophotometry, for the near real-time field analysis of small porewater samples. The procedure prevents known measurement biases associated with particulate sulfide interference, S2− volatilization and oxidation, and represents a practical approach for monitoring organic enrichment and classifying benthic ecological quality status. Porewater concentrations between 200 and 15,000 μmol L−1 can be measured and instrument calibration is highly stable. The method has the capacity to rapidly process and analyze sediment samples at low cost, which helps resolve the problem of chronic under-sampling associated with the use of traditional S2− methods.

测量海洋沉积物中总游离硫化物的简单快速方法
硫酸盐还原菌对海洋沉积物中的有机物进行矿化的最重要定量过程,导致孔隙水中总溶解(游离)硫化物(S2- = H2S + HS- + S2-)的积累。S2- 对底栖生物和维管植物具有毒性,其测量结果可代表有机物富集对底栖生物栖息地、生物多样性和生态系统功能的有害影响。测量水中 S2- 的方法至少已有一个世纪的历史,标准方法采用比色法(亚甲基蓝和碘滴定法)和电位法。这些标准方法需要 1 到 200 毫升的孔隙水,而获取孔隙水非常费力。离子选择电极法作为一种实用的沉积物 S2- 分析方法被广泛采用,但该方法缺乏分析稳定性,极易出现测量偏差,给研究和环境管理决策带来误导。本文介绍了一种技术简单的方法,该方法基于直接紫外分光光度法,可对小型孔隙水样本进行近实时现场分析。该方法可避免与微粒硫化物干扰、S2- 挥发和氧化有关的已知测量偏差,是监测有机富集和划分底栖生物生态质量状况的实用方法。可以测量 200 到 15,000 μmol L-1 的孔隙水浓度,仪器校准高度稳定。该方法能够以较低的成本快速处理和分析沉积物样本,有助于解决与使用传统 S2- 方法相关的长期采样不足的问题。
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来源期刊
CiteScore
4.80
自引率
3.70%
发文量
56
审稿时长
3 months
期刊介绍: Limnology and Oceanography: Methods (ISSN 1541-5856) is a companion to ASLO''s top-rated journal Limnology and Oceanography, and articles are held to the same high standards. In order to provide the most rapid publication consistent with high standards, Limnology and Oceanography: Methods appears in electronic format only, and the entire submission and review system is online. Articles are posted as soon as they are accepted and formatted for publication. Limnology and Oceanography: Methods will consider manuscripts whose primary focus is methodological, and that deal with problems in the aquatic sciences. Manuscripts may present new measurement equipment, techniques for analyzing observations or samples, methods for understanding and interpreting information, analyses of metadata to examine the effectiveness of approaches, invited and contributed reviews and syntheses, and techniques for communicating and teaching in the aquatic sciences.
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