Sowder Andrew G, Bertsch Paul M, Morris Pamela J
Savannah River Ecology Laboratory, The Univ. of Georgia, Drawer E. Aiken, SC 29802, USA.
J Environ Qual. 2003 May-Jun;32(3):885-98. doi: 10.2134/jeq2003.8850.
The effects of iron oxides and organic matter on the partitioning and chemical lability of U and Ni were examined for contaminated riparian sediments from the U.S. Department of Energy's Savannah River Site. In sequential extractions of four sediments that ranged from 12.7 to 82.2 g kg(-1) in organic carbon, U was found almost exclusively in moderately labile fractions (93% in acid-soluble + organically bound). Nickel was distributed across all operationally defined fractions, including substantial amounts in the very labile fractions (4-15% in water-soluble + exchangeable), noncrystalline and crystalline iron oxides (38-49%), and in the nonlabile residual fraction (25-34%). Aqueous U concentrations in 1:1 sediment-water extracts were highly correlated to dissolved organic carbon (DOC) (R2 = 0.96; p < 0.0001) and ranged from 29 to 410 microg L(-1). Aqueous concentrations of Ni exceeded U by two to three orders of magnitude (124-2227 microg L(-1)) but were not correlated with DOC (R2 = 0.04; p = 0.53). Partitioning and solubility trends suggest that Ni availability is controlled primarily by iron-oxide phases, whereas U availability is dominated by naturally occurring organic carbon. Discrete mineral phases were also identified as nonlabile reservoirs of anthropogenic metals. In spite of comparably high sediment concentrations, Ni appears to be significantly more available than U in riparian sediments and therefore warrants greater consideration in terms of environmental consequences (i.e., transport, biological uptake, and toxicity).
针对美国能源部萨凡纳河场地受污染的河岸沉积物，研究了铁氧化物和有机物对铀（U）和镍（Ni）分配及化学活性的影响。在对四种有机碳含量介于12.7至82.2 g kg⁻¹之间的沉积物进行连续萃取时，发现铀几乎完全存在于中度活性组分中（酸溶性 + 有机结合态占93%）。镍分布在所有按操作定义的组分中，包括大量存在于极易变组分中（水溶性 + 可交换态占4 - 15%）、非晶态和晶态铁氧化物中（38 - 49%）以及非活性残留组分中（25 - 34%）。1:1沉积物 - 水萃取液中的水相铀浓度与溶解有机碳（DOC）高度相关（R² = 0.96；p < 0.0001），范围为29至410 μg L⁻¹。镍的水相浓度比铀高出两到三个数量级（124 - 2227 μg L⁻¹），但与DOC不相关（R² = 0.04；p = 0.53）。分配和溶解度趋势表明，镍的有效性主要受铁氧化物相控制，而铀的有效性则主要由天然存在的有机碳主导。离散矿物相也被确定为人为金属的非活性储存库。尽管沉积物浓度相当高，但在河岸沉积物中，镍似乎比铀的有效性显著更高，因此在环境后果（即迁移、生物吸收和毒性）方面值得更多关注。
