Centre for Ecology & Hydrology, Bush Estate, Penicuik, EH26 0QB, Scotland, UK; School of GeoSciences, The University of Edinburgh, Crew Building, Alexander Crum Brown Road, Edinburgh, EH9 3FF, Scotland, UK.
School of GeoSciences, The University of Edinburgh, Crew Building, Alexander Crum Brown Road, Edinburgh, EH9 3FF, Scotland, UK.
Water Res. 2017 Oct 15;123:569-577. doi: 10.1016/j.watres.2017.07.009. Epub 2017 Jul 5.
Red mud is a by-product of alumina production. Little is known about the long-term fate of red mud constituents in fresh waters or of the processes regulating recovery of fresh waters following pollution control. In 1983, red mud leachate was diverted away from Kinghorn Loch, UK, after many years of polluting this shallow and monomictic lake. We hypothesised that the redox-sensitive constituents of red mud leachate, phosphorus (P), arsenic (As) and vanadium (V), would persist in the Kinghorn Loch for many years following pollution control as a result of cycling between the lake bed sediment and the overlying water column. To test this hypothesis, we conducted a 12-month field campaign in Kinghorn Loch between May 2012 and April 2013 to quantify the seasonal cycling of P, As, and V in relation to environmental conditions (e.g., dissolved oxygen (DO) concentration, pH, redox chemistry and temperature) in the lake surface and bottom waters. To confirm the mechanisms for P, As and V release, a sediment core incubation experiment was conducted using lake sediment sampled in July 2012, in which DO concentrations were manipulated to create either oxic or anoxic conditions similar to the bed conditions found in the lake. The effects on P, As, and V concentrations and species in the water column were measured daily over an eight-day incubation period. Phosphate (PO-P) and dissolved As concentrations were significantly higher in the bottom waters (75.9 ± 30.2 μg L and 23.5 ± 1.83 μg L, respectively) than in the surface waters (12.9 ± 1.50 μg L and 14.1 ± 2.20 μg L, respectively) in Kinghorn Loch. Sediment release of As and P under anoxic conditions was confirmed by the incubation experiment and by the significant negative correlations between DO and P and As concentrations in the bottom waters of the lake. In contrast, the highest dissolved V concentrations occurred in the bottom waters of Kinghorn Loch under oxic conditions (15.0 ± 3.35 μg L), with the release from the bed sediment apparently being controlled by a combination of competitive ion concentrations, pH and redox conditions.
赤泥是氧化铝生产的副产品。对于赤泥成分在淡水中的长期归宿，以及在污染控制后淡水恢复过程中起调控作用的各种过程，人们知之甚少。1983 年，在英国 Kinghorn 湖受到赤泥浸出液多年污染之后，该湖的赤泥浸出液被引走。我们假设，赤泥浸出液中的氧化还原敏感成分磷（P）、砷（As）和钒（V），在污染控制之后的许多年里，将在 Kinghorn 湖的湖底沉积物和上覆水柱之间循环，从而在湖水中持续存在。为了验证这一假说，我们于 2012 年 5 月至 2013 年 4 月在 Kinghorn 湖进行了为期 12 个月的野外考察，以定量确定 P、As 和 V 与湖水表层和底层水中的环境条件（如溶解氧（DO）浓度、pH 值、氧化还原化学和温度）之间的季节性循环。为了确认 P、As 和 V 释放的机制，我们于 2012 年 7 月使用从湖中采集的沉积物进行了一个沉积物核心培养实验，其中 DO 浓度被人为控制，以产生类似于在湖中发现的床条件的好氧或缺氧条件。在 8 天的培养期内，每天测量水柱中 P、As 和 V 的浓度和形态。磷（PO-P）和溶解态 As 的浓度在湖底水中（分别为 75.9 ± 30.2μg/L 和 23.5 ± 1.83μg/L）明显高于湖表层水中（分别为 12.9 ± 1.50μg/L 和 14.1 ± 2.20μg/L）。在缺氧条件下，沉积物中 As 和 P 的释放通过培养实验和 DO 与湖底层水中 P 和 As 浓度之间的显著负相关得到证实。相反，在好氧条件下，Kinghorn 湖底层水中的溶解态 V 浓度最高（15.0 ± 3.35μg/L），床沉积物的释放显然受到竞争离子浓度、pH 值和氧化还原条件的共同控制。
