Abstract：
Hydrothermal vent sites found along mid-ocean ridges are sources of numerous reduced chemical species and trace elements. To establish dissolved iron (II) (dFe(II)) variability along the Mid Atlantic Ridge (between 39.5°N and 26°N), dFe(II) concentrations were measured above six hydrothermal vent sites, as well as at stations with no active hydrothermal activity. The dFe(II) concentrations ranged from 0.00 to 0.12 nmol L-1 (detection limit = 0.02 ± 0.02 nmol L-1) in non-hydrothermally affected regions to values as high as 12.8 nmol L-1 within hydrothermal plumes. Iron (II) in seawater is oxidised over a period of minutes to hours, which is on average two times faster than the time required to collect the sample from the deep ocean and its analysis in the onboard laboratory. A multiparametric equation was used to estimate the original dFe(II) concentration in the deep ocean. The in-situ temperature, pH, salinity and delay between sample collection and its analysis were considered. The results showed that dFe(II) plays a more significant role in the iron pool than previously accounted for, constituting a fraction >20 % of the dissolved iron pool, in contrast to <10 % of the iron pool formerly reported. This discrepancy is caused by Fe(II) loss during sampling when between 35 and 90 % of the dFe(II) gets oxidised. In-situ dFe(II) concentrations are therefore significantly higher than values reported in sedimentary and hydrothermal settings where Fe is added to the ocean in its reduced form. Consequently, the high dynamism of dFe(II) in hydrothermal environments masks the magnitude of dFe(II) sourced within the deep ocean.
摘要：
沿大洋中脊发现的热液喷口是许多减少的化学物质和微量元素的来源。建立沿大西洋中脊（39.5°N和26°N之间）的溶解铁（II）（dFe（II））变异性，在六个热液喷口以上测量dFe(II)浓度，以及没有活跃热液活动的站点。在非水热影响区域中，dFe（II）的浓度范围为0.00至0.12nmolL-1（检测限=0.02±0.02nmolL-1），在热液羽流中的值高达12.8nmolL-1。海水中的铁（II）在几分钟到几小时内被氧化，平均而言，这比从深海收集样本并在船上实验室进行分析所需的时间快两倍。使用多参数方程估算深海中的原始dFe（II）浓度。现场温度,pH值,考虑了样品收集和分析之间的盐度和延迟。结果表明，dFe(Ⅱ)在铁池中的作用比以前的解释更显著，构成>20%的溶解铁池的一部分，与之前报道的<10％的铁池相反。这种差异是由采样过程中35至90%的dFe(II)被氧化时的Fe(II)损失引起的。因此，原位dFe（II）的浓度明显高于沉积和热液环境中报道的值，其中Fe以还原形式添加到海洋中。因此,热液环境中dFe（II）的高动态性掩盖了深海中dFe（II）的大小。
