Division of Life Science, Rutgers University, 604 Allison Road, Piscataway, NJ, 08854, USA.
Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, NJ, 08854, USA.
Environ Sci Pollut Res Int. 2021 Apr;28(15):18392-18406. doi: 10.1007/s11356-020-12175-z. Epub 2021 Jan 20.
The mutual mitigation of selenium and mercury toxicity is particularly interesting, especially for humans. Mercury is widely recognized as a pantoxic element; all forms are toxic to all organisms. Less well known is that selenium in excess is toxic as well. The high affinity between these elements influences their bioavailability and toxicity. In this paper, we use selected species from Barnegat and Delaware Bays in New Jersey to examine variations in levels of selenium and mercury, and selenium:mercury molar ratios between and within species. We report on species ranging from horseshoe crab eggs (Limulus polyphemus), a keystone species of the food chain, to several fish species, to fish-eating birds. Sampling began in the 1970s for some species and in the 1990s for others. We found no clear time trends in mercury levels in horseshoe crab eggs, but selenium levels declined at first, then remained steady after the mid1990s. Concentrations of mercury and selenium in blood of migrant shorebirds directly reflected levels in horseshoe crab eggs (their food at stopover). Levels of mercury in eggs of common terns (Sterna hirundo) varied over time, and may have declined slightly since the mid2000s; selenium levels also varied temporally, and declined somewhat. There were variations in mercury and selenium levels in commercial, recreational, and subsistence fish as a function of species, season, and size (a surrogate for age). Selenium:mercury molar ratios also varied as a function of species, year, season, and size in fish. While mercury levels increased with size within individual fish species, selenium levels remained the same or declined. Thus selenium:mercury molar ratios declined with size in fish, reducing the potential of selenium to ameliorate mercury toxicity in consumers. Mercury levels in fish examined were higher in early summer and late fall, and lower in the summer, while selenium stayed relatively similar; thus selenium:mercury molar ratios were lower in early summer and late fall than in midsummer. We discuss the importance of temporal trends in biomonitoring projects, variations in levels of mercury, selenium, and the molar ratios as a function of several variables, and the influence of these on risks to predators and humans eating the fish, and the eggs of gulls, terns. Our data suggests that variability limits the utility of the selenium:mercury molar ratio for fish consumption advisories and for risk management.
硒和汞毒性的相互缓解特别有趣，特别是对人类而言。汞被广泛认为是一种泛毒性元素；所有形式的汞对所有生物都有毒。而硒过量也有毒这一点则鲜为人知。这两种元素之间的高亲和力影响了它们的生物利用度和毒性。在本文中，我们使用新泽西州巴内加特湾和特拉华湾的选定物种来研究硒和汞的水平以及物种内和物种间硒与汞的摩尔比的变化。我们报告了从马蹄蟹卵（Limulus polyphemus）（食物链的关键物种）到几种鱼类，再到食鱼鸟类的各种物种。一些物种的采样始于 20 世纪 70 年代，而另一些物种则始于 20 世纪 90 年代。我们发现马蹄蟹卵中的汞水平没有明显的时间趋势，但硒水平最初下降，然后在 20 世纪 90 年代中期后保持稳定。候鸟血液中的汞和硒浓度直接反映了马蹄蟹卵中的水平（它们在停留时的食物）。普通燕鸥（Sterna hirundo）卵中的汞含量随时间而变化，自 21 世纪中叶以来可能略有下降；硒水平也随时间而变化，略有下降。商业、娱乐和自给性鱼类中的汞和硒水平因物种、季节和大小（年龄的替代物）而异。鱼类中的汞和硒水平也因物种、年份、季节和大小而变化。虽然在单个鱼类物种中，汞水平随个体大小而增加，但硒水平保持不变或下降。因此，随着鱼类个体的大小，硒与汞的摩尔比下降，从而降低了硒缓解消费者体内汞毒性的潜力。检查的鱼类中的汞含量在初夏和晚秋较高，在夏季较低，而硒含量相对稳定；因此，初夏和晚秋的硒与汞的摩尔比低于仲夏。我们讨论了生物监测项目中时间趋势的重要性、汞、硒和摩尔比随几个变量的变化以及这些因素对捕食者和食用鱼类及其鸥、燕鸥卵的人的风险的影响。我们的数据表明，可变性限制了硒与汞的摩尔比在鱼类消费建议和风险管理中的应用。
