Zhu Y, Guéguen C
Environmental and Life Sciences Graduate Program, Trent University, ON, Canada.
Chemistry Department, Trent University, ON, Canada.
Environ Pollut. 2016 Dec;219:1140-1147. doi: 10.1016/j.envpol.2016.09.018. Epub 2016 Sep 13.
The Athabasca's oil sands exploitation is controversial due to its potential risks to water quality but little is known about the temporal changes in the most bioavailable fraction of metal, the free/labile species. In this study, diffusive gradient in thin films (DGT) and the Windermere Humic Aqueous Model (WHAM VII) equilibrium model were used to examine the temporal changes in free/labile metal (Cu, Ni, Zn, Pb) species in three tributaries of the north-flowing Athabasca River in the Athabasca oil sands region (AOSR). The influence of dissolved organic matter (DOM) composition (i.e. fulvic: humic ratio) on modeled Cu and Ni speciation showed a negligible effect on the labile concentration. The best agreements (92 ± 8%) between DGT-labile and WHAM calculated labile concentrations were found assuming the formation of iron oxyhydroxides (FeO(OH)). The agreement was only 70 ± 7% in the presence of inorganic colloidal aluminum oxyhydroxides (AlO(OH)) and in the absence of any inorganic colloids. Together these results suggest that a change in DOM composition had limited impacts on modeled free metal ion concentrations. Although the concentration of the main metal ligand (i.e. DOM), varied from 9 to 40 ppm, no significant temporal differences in the abundance of WHAM-modeled labile species were found, suggesting mobility and bioavailability of Cu, Ni, Pb and Zn were comparable over the 2003-2012 period.
阿萨巴斯卡油砂的开采颇具争议，因为其对水质存在潜在风险，但对于金属中生物可利用性最高的部分，即游离/不稳定形态，随时间的变化却知之甚少。在本研究中，采用薄膜扩散梯度技术（DGT）和温德米尔腐殖酸水模型（WHAM VII）平衡模型，研究了阿萨巴斯卡油砂地区（AOSR）向北流淌的阿萨巴斯卡河三条支流中游离/不稳定金属（铜、镍、锌、铅）形态随时间的变化。溶解有机物（DOM）组成（即富里酸与腐殖酸的比例）对模拟的铜和镍形态的影响表明，对不稳定浓度的影响可忽略不计。假设形成羟基氧化铁（FeO(OH)）时，DGT测定的不稳定浓度与WHAM计算的不稳定浓度之间的一致性最佳（92±8%）。在存在无机胶体氢氧化铝（AlO(OH)）且不存在任何无机胶体的情况下，一致性仅为70±7%。这些结果共同表明，DOM组成的变化对模拟的游离金属离子浓度影响有限。尽管主要金属配体（即DOM）的浓度在9至40 ppm之间变化，但未发现WHAM模拟的不稳定形态丰度存在显著的时间差异，这表明在2003 - 2012年期间，铜、镍、铅和锌的迁移性和生物可利用性具有可比性。
