Harper Colleen O, Amos Richard T
Department of Earth Sciences, Carleton University, 1125 Colonel By Dr, Ottawa, ON, K1S 5B6, Canada.
Heliyon. 2024 Dec 13;11(1):e41223. doi: 10.1016/j.heliyon.2024.e41223. eCollection 2025 Jan 15.
Metal mining operations can release toxic metals to surrounding environments where site-specific conditions control the movement of contaminants. Colloid-facilitated transport, the transport of contaminants with small, mobile particles, has been recognized as a potential contaminant transport vector in groundwater, but it remains unclear under what conditions it is important and whether neutral, metal-rich mine drainage from legacy mining impacts this transport vector. This work presents a set of laboratory column experiments that study the effect of colloids on metal mobility in saturated, wetland sediment that has been receiving neutral mine drainage for nearly a century, using mixed and single metal input solutions at neutral pH. Results indicate that colloid-facilitated transport is only important when small (<0.01 μm) colloids, most likely formed from organic matter, are present. Larger particles were found to be generally immobile, so could aid in the immobilization of metal contaminants. These findings imply that colloid-facilitated transport is an important transport vector in mine-impacted wetland sediment and should be considered when remediating mine sites.
金属采矿作业会将有毒金属释放到周围环境中，而特定场地条件会控制污染物的迁移。胶体促进迁移，即污染物随小的可移动颗粒迁移，已被认为是地下水中一种潜在的污染物迁移载体，但目前尚不清楚在何种条件下它很重要，以及来自遗留采矿的中性、富含金属的矿井排水是否会影响这种迁移载体。这项工作展示了一组实验室柱实验，研究了胶体对饱和湿地沉积物中金属迁移率的影响，该湿地沉积物近一个世纪以来一直接收中性矿井排水，实验使用了中性pH值的混合和单一金属输入溶液。结果表明，只有当存在可能由有机物形成的小（<0.01μm）胶体时，胶体促进迁移才很重要。发现较大颗粒通常是不可移动的，因此有助于固定金属污染物。这些发现表明，胶体促进迁移是受采矿影响的湿地沉积物中的一种重要迁移载体，在修复矿场时应予以考虑。
