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首页> 外文期刊>Journal of soil & sediments >Assessment of lead and beryllium sorption to exposed stream channel sediment under varying freshwater channel conditions
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Assessment of lead and beryllium sorption to exposed stream channel sediment under varying freshwater channel conditions

机译：在变化的淡水河道条件下评估铅和铍对暴露的河道沉积物的吸附

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Purpose Beryllium (Be) and lead (Pb) sorption is important to the utility of the radioisotopes of these elements for sediment fingerprinting. This paper examines the sorption of Be and Pb exposed to fluvial sediment under varying chemical conditions representative of freshwater streams draining two distinct Critical Zone environments in the eastern United States: the mid-Atlantic piedmont and heavily glaciated Great Lakes region. Materials and methods Batch experiments were completed using well-characterized in-stream deposit sediments collected from these two systems and varying solutions to reflect background and elevated levels of iron oxide in the form of goethite across times ranging from 0.25 to 360 h. The mid-Atlantic piedmont sediment had further treatments testing dissolved organic carbon and increased sediment to solution ratio effects on Pb and Be sorption. Results and discussion Beryllium partition coefficients (K-d) ranged from a log K-d of 1.46 to 3.48 L kg(-1) and Pb ranged from 0 to 5.03 L kg(-1) across all treatments displaying several noticeable patterns. Two-stage sorption was observed such that sorption increased over time across all treatments and substrates. Goethite additions either enhanced or reduced sorption relative to the unaltered treatment depending on the original sediment and mixing time. Lead sorption with the addition of 100 mg of goethite increased during shorter mixing times before being surpassed by the unaltered, or base, treatment at longer mixing times for both the mid-Atlantic piedmont and glaciated Great Lakes sediment. Beryllium sorption was increased with the mid-Atlantic piedmont sediment whereas it was primarily decreased with the glaciated Great Lakes sediment. The 1 mg of goethite generally showed equal to or slightly enhanced sorption relative to the base setup of both Pb and Be with the exception of Pb sorption to the Great Lakes sediment. The highest DOC concentration tested of 11.86 mg L-1 retained a greater amount of Be and Pb in solution compared to other treatments after 360 h. Increasing the sediment to solution ratio showed decreased partition coefficients across all analogous times for Be compared to the base treatment whereas Pb sorption surpassed the unaltered treatment after 24 h. Conclusions These results suggest that fluvial sediment mineralogy, organic matter concentration, and biogeochemical cycling of common stream chemical constituents may play a role in the mobilization or retention of these two trace metals and alter their utility for sediment fingerprinting.
机译：目的铍（Be）和铅（Pb）的吸附对于这些元素的放射性同位素用于沉积物指纹分析的用途很重要。本文研究了在变化的化学条件下暴露于河流沉积物中的Be和Pb的吸附情况，这些条件代表着淡水流在美国东部的两个不同的关键区环境中的排放：大西洋中部的山前丘陵和大冰河地区的大湖区。材料和方法使用从这两个系统中收集到的特征明确的流内沉积物沉淀物和不同的溶液来完成批处理实验，以反映从0.25到360 h范围内针铁矿形式的氧化铁的本底和升高的水平。大西洋中部的山前沉积物经过进一步处理，测试了溶解的有机碳，并增加了沉积物与溶液之比对Pb和Be吸附的影响。结果与讨论在所有处理中，铍分配系数（K-d）的对数K-d为1.46至3.48 L kg（-1），Pb的范围为0至5.03 L kg（-1），显示出几种明显的模式。观察到两阶段吸附，使得所有处理和底物的吸附随时间增加。相对于未改变的处理，针铁矿的添加会增加或减少吸附，具体取决于原始沉积物和混合时间。在较短的混合时间内，添加了100 mg针铁矿的铅吸附量就增加了，而在大西洋中部的前山和冰川的大湖沉积物的混合时间较长的情况下，铅的吸附量没有改变。铍吸附随着大西洋中部山前沉积物的增加而增加，而主要随着冰河大湖沉积物的减少而减少。 1 mg针铁矿相对于Pb和Be的基本结构通常表现出相同或略有增强的吸附作用，除了对大湖沉积物的Pb吸附作用。在360小时后，与其他处理相比，测试的最高DOC浓度为11.86 mg L-1可以在溶液中保留更多的Be和Pb。与基础处理相比，增加的沉积物溶液比在所有相似的时间内都显示出降低的分配系数，而24小时后，Pb的吸附超过了未改变的处理。结论这些结果表明，河流沉积物的矿物学，有机物浓度和常见流化学成分的生物地球化学循环可能在这两种微量金属的动员或保留中起作用，并改变了它们在沉积物指纹识别中的作用。

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