YREE scavenging in seawater: A new look at an old model
YREE scavenging in seawater: A new look at an old model
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DOI：
10.1016/j.marchem.2015.06.010
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发表时间：
2015-12
期刊：
影响因子：
3
通讯作者：
J. Schijf;E. Christenson;R. Byrne
中科院分区：
文献类型：
--
作者：
J. Schijf;E. Christenson;R. Byrne
在海洋中，钇和稀土元素（YREE）显示出类似营养物的垂直分布。由于YREE没有明显的生物学功能，它们从溶液中的去除（清除）可能是由颗粒吸附而不是活性微生物吸收引起的，但这些颗粒的确切性质尚不确定。现有的理论模型将清除描述为与溶解的无机配体和与颗粒表面上的官能团的络合之间的平衡。该模型能够预测输入归一化（即，页岩标准化）YREE丰度模式在海水中，而不需要像颗粒浓度或网站密度的功能团知之甚少的参数。采用公认的稳定性无机YREE络合物，同时假设吸附剂颗粒是有机的，由简单的一元羧酸的混合物代表的官能团，它再现了海水YREE模式的一些关键特征，特别是页岩归一化丰度与原子序数和某些三价稀土元素（镧和钆）的显着异常的特征增加。熟悉的负Ce异常的海水，然而，是由于氧化还原反应，没有明确accounted.In这项研究中，我们完善了计算YREE溶液的形态，通过添加络合与去铁胺B，以衡量强有机配体的影响，普遍在海洋表面附近。清除模型，然后通过减去高品质的YREE丰度模式，报告的公海，从这个解决方案的形态产生的平均模式的相对YREE亲和力的吸附剂颗粒。由此产生的亲和图案进行比较与图案的分配系数，来自实验室实验，YREE吸附在相关的固相，包括水合铁和锰的氧化物（HFO/HMO），方解石，和绿色macroalgaUlva lactucaas海洋有机质的替代品。对于深海，最好的协议是观察与HMO，这可能是YREE的沉积物的主要载体。由于铈在氧化锰表面上被催化氧化，这可能对铈异常的演变产生影响。直接比较的分布系数模式与YREE分析的悬浮颗粒从大西洋也有利于HMO，但这可能是在一种情况下，通过使用选择性浸出方法。对于浅海，特别是大西洋，最好的协议是观察与U。莴苣和方解石，尽管后者被这种生物矿物的低YREE含量所抵消。与HFO的匹配通常不太令人信服。上述简单一元羧酸的混合物不是海洋有机物吸附性能的良好代表。
In the ocean, yttrium and the rare earth elements (YREEs) show nutrient-like vertical profiles. Since the YREEs have no manifest biological function, their removal from solution (scavenging) is probably caused by sorption on particles rather than active microbial uptake, yet the exact nature of these particles is uncertain. An existing theoretical model describes scavenging as an equilibrium between complexation with dissolved inorganic ligands and with functional groups on particle surfaces. This model was able to predict input-normalized (i.e., shale-normalized) YREE abundance patterns in seawater without requiring poorly known parameters like particle concentrations or the site densities of functional groups. Employing well-established stabilities of inorganic YREE complexes, while assuming that the sorbent particles are organic with functional groups represented by a mixture of simple monocarboxylic acids, it reproduced some key features of seawater YREE patterns, specifically the characteristic increase of shale-normalized abundance with atomic number and distinctive anomalies of certain trivalent REEs (La and Gd). The familiar negative Ce anomaly of seawater, however, is due to redox reactions that were not explicitly accounted for.In this study, we refined calculations of YREE solution speciation by adding complexation with desferrioxamine B to gauge the influence of strong organic ligands prevalent near the ocean surface. The scavenging model was then inverted by subtracting high-quality YREE abundance patterns, reported for the open ocean, from this solution speciation to yield an average pattern of relative YREE affinities for the sorbent particles. The resulting affinity pattern is compared with patterns of distribution coefficients, derived from laboratory experiments, for YREE sorption on relevant solid phases including hydrated Fe and Mn oxides (HFO/HMO), calcite, and the green macroalgaUlva lactucaas a substitute for marine organic matter. For deep seawater, the best agreement is observed with HMO, which may thus be the dominant carrier of YREEs to the sediment. Since Ce is catalytically oxidized on manganese oxide surfaces, this could have implications for the evolution of the Ce anomaly. Direct comparisons of distribution coefficient patterns with YREE analyses of suspended particles from the Atlantic Ocean also favor HMO, but this may be dictated in one case by the use of a selective leaching method. For shallow seawater, particularly in the Atlantic Ocean, the best agreement is observed withU. lactucaand calcite, although the latter is offset by the low YREE contents of this biogenic mineral. Matches with HFO are generally less convincing. The aforementioned mixture of simple monocarboxylic acids is not a good proxy for the sorptive properties of marine organic matter.