Although fish is an important source of nutrients, including some of the healthiest proteins, long-chain fatty acids, and essential selenium, species at the top of the food chain frequently contain large amounts of toxic mercury (Hg). The provisional tolerable weekly intake (PTWI) of Hg from fish consumption is calculated from the total concentration of Hg and assuming that all Hg is speciated as organic methylmercury (MeHg). Using high energy-resolution X-ray absorption near-edge structure (HR-XANES) spectroscopy, we show that blue marlin (Makaira sp.), a common top predator consumed by humans, contains high concentrations of inorganic Hg(II) complexed as 57 ± 10% Hg-tetraselenolate [Hg(Sec)₄] and 43 ± 10% tiemannite (HgSe). The stable Hg–Se chemical bond likely attenuates the bioavailability of Hg and counteracts some of its health hazards to consumers. Thus, monitoring the concentration of MeHg, rather than total Hg, in top predators such as marlin would provide a more robust measure of potential Hg exposure and may be sufficient for food safety controls. The bonding of Hg atoms to four selenocysteine (Sec) residues in the Hg(Sec)₄ complex severely depletes the stock of bioavailable Se, and quantification shows that blue marlin is not a chief source of dietary Se essential to selenoenzyme synthesis and activity.

中文翻译：

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蓝枪鱼鳞鱼中汞的化学形式：对人体暴露的影响

尽管鱼类是重要的养分来源，包括一些最健康的蛋白质，长链脂肪酸和必需硒，但食物链顶部的物种经常含有大量有毒的汞（Hg）。鱼类消费中汞的暂定每周耐受摄入量（PTWI）是根据汞的总浓度计算得出的，并假设所有汞均指定为有机甲基汞（MeHg）。使用高能量分辨率的X射线吸收近边缘结构（HR-XANES）光谱，我们显示了蓝马林鱼（Makaira sp。）是人类消耗的常见顶级捕食者，其中含有高浓度的无机汞（II） 57±10％四氢硒酸汞[Hg（Sec）₄]和43±10％的铁锰矿（HgSe）。稳定的Hg-Se化学键可能会削弱Hg的生物利用度，并抵消其对消费者的健康危害。因此，监测顶级捕食者（例如马林鱼）中的MeHg浓度而不是总Hg浓度将提供更可靠的潜在Hg暴露量，并且可能足以控制食品安全。Hg原子与Hg（Sec）₄复合物中的四个硒代半胱氨酸（Sec）残基的键合会严重消耗可生物利用的Se的储备，并且定量显示蓝马林不是硒中硒酶合成和活性必不可少的主要膳食硒来源。