State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Number 73 Beijing East Road, 210008, Nanjing, People's Republic of China.
CEER, Nanjing Hydraulic Research Institute, Nanjing, 210029, People's Republic of China.
Environ Sci Pollut Res Int. 2018 Sep;25(25):24682-24694. doi: 10.1007/s11356-018-2432-1. Epub 2018 Jun 18.
In eutrophic lake restorations, in situ capping is an often considered method to control sediment internal phosphorus (P) pollution for mitigating eutrophication status. Subsequent aquatic macrophyte revegetation can directly derive P from the sediment for growth. However, the effects of capping with clean soils on internal P release from sediments under rooted aquatic macrophyte revegetation are still unclear. In the present study, the influences of sediment P remobilization by P. australis revegetation on P inactivation by capping were investigated based on an entire growth simulation study. Our findings showed during the growth of P. australis, tests conducted on total phosphorous (TP), calcium-bound P (Ca-P), loosely bound P (loose-P), organic P (Org-P), and iron-adsorbed P (Fe-P) found significant changes (p < 0.001). Specifically, the mean contents of TP and Ca-P decreased by 291.1 and 224.2 mg kg, respectively, while those of Fe-P increased from 26.4 to 124.8 mg kg. In addition, sediment mobile-P contents increased coincidentally with the growth of P. australis during the whole course of experiment. Further analysis indicated calculated diffusion fluxes of soluble reactive phosphorus (SRP) generally increased with incubation time, although capping effectively induced the reduction of SRP concentration in pore water and its release to waters. Therefore, sediment P remobilization by P. australis revegetation was able to enhance P lability in lake sediments, with intermediate activation ability compared to other correlated water bodies. This phenomenon was most likely attributed to solubilization of sediment P by organic acids secreted from P. australis rhizosphere. Overall, sediment P remobilization by rooted macrophytes is unfavorable for capping to control internal P release to water column during eutrophic lake restorations.
在富营养化湖泊修复中，原位覆盖是一种常用的控制沉积物内部磷（P）污染的方法，以减轻富营养化状况。随后水生大型植物的重新种植可以直接从沉积物中获取 P 进行生长。然而，在有根水生大型植物重新种植的情况下，用清洁土壤覆盖对沉积物内部 P 释放的影响仍不清楚。本研究基于整个生长模拟研究，调查了磷质植物（P. australis）重新种植对 P 固定的影响。研究结果表明，在 P. australis 的生长过程中，对总磷（TP）、钙结合磷（Ca-P）、松散结合磷（loose-P）、有机磷（Org-P）和铁吸附磷（Fe-P）的测试表明，有显著变化（p < 0.001）。具体而言，TP 和 Ca-P 的平均含量分别减少了 291.1 和 224.2 mg kg，而 Fe-P 的含量从 26.4 增加到 124.8 mg kg。此外，在整个实验过程中，随着 P. australis 的生长，沉积物的移动磷含量也随之增加。进一步的分析表明，计算出的可溶性反应磷（SRP）扩散通量通常随培养时间的增加而增加，尽管覆盖有效地降低了孔隙水中 SRP 的浓度及其向水体中的释放。因此，P. australis 重新种植引起的沉积物 P 再移动能够增强湖泊沉积物中的 P 可利用性，与其他相关水体相比具有中等的激活能力。这种现象很可能归因于 P. australis 根际分泌的有机酸对沉积物 P 的溶解。总的来说，有根大型植物引起的沉积物 P 再移动不利于覆盖控制富营养化湖泊修复过程中内部 P 向水柱的释放。
