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首页> 外文期刊>Marine Chemistry >Influence of salinity and humic substances on the uptake of trace metals by the marine macroalga, Ulva lactuca: Experimental observations and modelling using WHAM
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Influence of salinity and humic substances on the uptake of trace metals by the marine macroalga, Ulva lactuca: Experimental observations and modelling using WHAM

机译：盐度和腐殖质对海洋大型藻（Ulva lactuca）摄取微量金属的影响：使用WHAM进行的实验观察和建模

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摘要

Uptake of the trace metals, Pd, Cd, Hg and Pb, by the marine macroalga, Ulva lactuca, has been studied along a salinity gradient (S=15-35; pH ～ 8.3) created by batch mixing of synthetic sea water and pure water, both in the absence and presence of humic substances. Factors defining the concentration ratio of metal taken up (w/w) to metal remaining in solution ranged from about 10~2 mL g~(-1) for Cd to 10~3 mL g~(-1) for Pd and Hg. Within experimental error, only the biouptake of Cd appeared to exhibit a dependence on salinity, while the addition of 3 mg L~(-1) of humics resulted in a small suppression of Pd and Hg uptake and a moderate enhancement of Pb uptake compared with the humic-free system. Metal internalisation, evaluated from an EDTA wash of the alga, followed the sequence: Hg>Pd>Cd>Pb; and was notably inhibited in the presence of humics for Pb. Metal uptake (as adsorption and internalisation) was modelled using the Windermere Humic Aqueous Model (WHAM, v6) by encoding the macroalga as a polyelectrolytic binding phase whose properties were defaulted to those of aqueous humics in the software database. By setting the "activity" of the binding phase to about 0.1 and systematically reducing the default constants for metal binding, the magnitude of metal uptake by U. lactuca was reproduced. However, for all metals the model predicted a reduction in algal uptake as a function of salinity that was not always observed experimentally. Moreover, calculations performed in the presence of aqueous humic substances and using the earlier fitted constants significantly underestimated metal uptake by U. lactuca. Discrepancies between experimental observations and model calculations, which are attributed to the formation of ternary complexes at the algal surface, suggest that conventional equilibrium speciation considerations alone are not applicable for modelling metal interactions with marine macroalgae.
机译：已研究了通过合成海水和纯净水的批量混合产生的盐度梯度（S = 15-35； pH〜8.3），海洋大型藻类Ulva lactuca对痕量金属Pd，Cd，Hg和Pb的吸收。在没有和有腐殖质存在下的水。决定溶液中所吸收的金属与残留金属的浓度比（w / w）的范围从Cd的约10〜2 mL g〜（-1）到Pd和Hg的10〜3 mL g〜（-1）。在实验误差范围内，仅镉的生物吸收似乎表现出对盐度的依赖性，而与腐殖质相比，添加3 mg L〜（-1）腐殖质导致对Pd和Hg吸收的抑制作用较小，并且对Pb的吸收具有适度的增强作用。无人的系统。由藻类的EDTA洗涤评估金属内在化，其顺序为：Hg> Pd> Cd> Pb；并且在腐殖质存在下对Pb具有明显的抑制作用。使用温德米尔腐殖酸水模型（WHAM，v6）对金属吸收（作为吸附和内在化）进行建模，方法是将大型藻类编码为聚电解结合相，其属性默认为软件数据库中的腐殖质水溶液。通过将结合相的“活性”设定为约0.1，并系统地降低金属结合的默认常数，可再现乳酸菌对金属的吸收量。但是，对于所有金属，该模型都预测藻类摄入量随盐度的降低而降低，这在实验中并不总是观察到的。而且，在含水腐殖质存在下并使用较早的拟合常数进行的计算大大低估了U. lactuca对金属的吸收。实验观察值与模型计算之间的差异是由于藻类表面三元复合物的形成所致，表明仅传统的平衡形态学考虑因素不适用于建模金属与海洋大型藻类的相互作用。

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