稳定的同位素将大气来源限制在海洋中
Martin Jiskra1,2, Lars-Eric Heimbürger-Boavida3,4, Marie-Maëlle Desgranges5
1Environmental Geosciences, University of Basel, Basel, Switzerland. martin.jiskra@unibas.ch.
Nature
|September 30, 2021
概括
人类食用海鲜是有毒 (Hg) 暴露的主要来源. 这项研究表明,海洋吸收气态 (Hg) 和 (Hg) 沉积是海洋的同样重要的途径.
科学领域:
- 环境化学
- 海洋生物地质化学
- 同位素地化学
背景情况:
- 人类接触有毒 (Hg) 主要是通过食用海鲜.
- 地球系统模型显示大气沉积 (Hg) 是海洋的主要来源,气态 (Hg) 的吸收较少.
- 目前对海洋Hg(II) 沉积和Hg(0) 气体交换的观察是有限的,导致了解水银的海洋来源存在不确定性.
研究的目的:
- 量化大气中的沉积途径进入海洋生态系统.
- 研究Hg(II) 沉积和Hg(0) 吸收对海水总 (tHg) 的相对贡献.
- 分析全球海洋同位素数据以了解循环的度变化.
主要方法:
- 在大西洋和地中海海水中测量稳定 (Hg) 同位素的总 (tHg).
- 应用稳定同位素质量平衡模型 (Δ200Hg) 来估计沉积路径.
- 收集和分析全球海洋Hg同位素数据,包括Hg颗粒,沉积物和生物群.
主要成果:
- 海水的tHg同位素组成在表面和深层样本中是相似的,在Hg(0) 和Hg(II) 末端之间有 Δ200Hg 的中位数.
- 海水的Hg同位素质量平衡 tHg是由42%的大气Hg(II) 总沉积和58%的Hg(0) 总吸收的混合物产生的.
- 观察到一个度 Δ200Hg 的梯度,表明在更高度的海洋中气的吸收量更大.
结论:
- 全球海洋吸收大气Hg(0) 的量相当于Hg(II) 的沉积量.
- 这一发现挑战了以前关于散的假设,并对了解海洋生态系统在污染后的恢复有重大影响.
- 水银稳定同位素为海洋环境中复杂的生态化学循环过程提供了强大的工具.
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