Centre for Ecology & Hydrology, Penicuik, Midlothian, Scotland EH26 0QB, UK.
Water Res. 2013 Sep 1;47(13):4460-73. doi: 10.1016/j.watres.2013.05.017. Epub 2013 May 21.
Phoslock(®) is increasingly used worldwide to control sediment phosphorus (P) release and cyanobacterial blooms despite the fact that little is known about its mode of action in lake bed sediments. This study quantified the effects of Phoslock(®) on sediment elemental composition and P fractionation (one year pre- and post-application of 170 g Phoslock(®) m(-2)) in an attempt to address these knowledge gaps. Post-application, sediment La content was significantly higher in the top 10 cm of the sediment compared to pre-application conditions. Mass balance calculations indicated that the applied mass of La had the potential to bind 25% of potentially release-sensitive P (Pmobile; sum 'labile P', 'reductant-soluble P' and 'organic P' fraction) present in the top 4 cm or 10% of Pmobile present in the top 10 cm of the sediment. Assessing variation in sediment P partitioning indicated that the application caused a significant increase in the mass of P present in the more refractory 'apatite bound P' fraction between post-application month 4 and 7 compared to Pmobile. This suggests that Phoslock(®) controls sediment P release by increasing the mass of P permanently bound in the sediment. To address uncertainty in estimating product dose required to control sediment P release we conducted laboratory assays using intact sediment cores to which we added serial additions of Phoslock(®) under either aerobic or anaerobic conditions. The laboratory experiment indicated that the original dose to Loch Flemington was sufficient to control sediment P release under aerobic conditions but that significant P release will occur should prolonged anaerobic conditions persist. However, Phoslock(®) may be a viable option to control sediment P-release under anaerobic conditions which would require an estimated additional application of up to 510 g Phoslock(®) m(-2). A conceptual model is proposed for the use of P-capping agents in lake remediation projects which is likely to increase cost-effectiveness and reduce non-target effects by applying multiple smaller doses compared to a single high dose.
Phoslock(®) 越来越多地被全世界用于控制沉积物磷 (P) 的释放和蓝藻水华，尽管人们对其在湖底沉积物中的作用模式知之甚少。本研究量化了 Phoslock(®) 对沉积物元素组成和 P 分馏的影响（应用 170 g Phoslock(®) m(-2) 前后一年），试图解决这些知识空白。应用后，与应用前条件相比，沉积物中前 10 厘米的 La 含量明显更高。质量平衡计算表明，施加的 La 质量有可能结合存在于前 4 厘米或沉积物前 10 厘米中 10%的 Pmobile 中 25%的潜在释放敏感 P（Pmobile；“可利用磷”、“还原剂可溶磷”和“有机磷”之和）。评估沉积物 P 分配的变化表明，与 Pmobile 相比，在应用后 4 至 7 个月期间，应用导致“磷灰石结合磷”中存在的 P 质量显著增加。这表明 Phoslock(®) 通过增加沉积物中永久结合的 P 质量来控制沉积物 P 的释放。为了解决估计控制沉积物 P 释放所需产品剂量的不确定性，我们使用完整的沉积物岩芯进行了实验室试验，在有氧或无氧条件下向这些岩芯中添加了一系列 Phoslock(®) 添加物。实验室实验表明，Loch Flemington 的原始剂量足以在有氧条件下控制沉积物 P 的释放，但如果持续存在长时间的无氧条件，将发生显著的 P 释放。然而，Phoslock(®) 可能是控制缺氧条件下沉积物 P 释放的可行选择，这可能需要额外施加约 510 g Phoslock(®) m(-2)。提出了一个用于湖泊修复项目中 P 封盖剂的概念模型，与单一高剂量相比，通过施加多个较小剂量，可能会提高成本效益并减少非目标效应。
