State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing, 210098, China.
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China.
Environ Sci Pollut Res Int. 2020 Mar;27(7):7538-7548. doi: 10.1007/s11356-019-07404-z. Epub 2019 Dec 29.
The effects of chironomid larval (Propsilocerus akamusi) bioturbation on sediment phosphorus (P) mobility were studied over the course of 34 days using the indoor larval cultivation method on in situ sediment cores. High-resolution dialysis (HR-Peeper) and diffusive gradients in thin films (DGT) techniques were used to record fine-scale changes of soluble and DGT-labile P and iron (Fe) concentrations in the sediment. The larval-driven irrigation of the overlying water into their burrows significantly increased the oxygen penetration depth (OPD) and redox state (Eh) in sediments. In addition, the soluble and DGT-labile P and Fe decreased with the increase of OPD and Eh in larval-bioturbated sediments. The greatest decrease in the mean concentration of SRP, soluble Fe, and DGT-labile P in the Propsilocerus group was observed on Day 15 of the experiment, with a decrease by over half of the mean concentration of the control group. Furthermore, two-dimensional measurements of DGT-labile P concentration showed notable reductions of DGT-labile P around larval burrows. The DGT-induced fluxes in sediments (DIFS) model also exhibited a much longer response time (420 s) and a much higher rate of P adsorption (0.002 s) in the bioturbation sediments than those in the control sediments (116 s and 0.009 s, respectively). A significant correlation was shown for DGT-labile P and DGT-labile Fe. We conclude that Fe(II) oxidation and its enhanced adsorption were the major mechanisms responsible for the decrease of soluble and DGT-labile P in sediments.
室内幼虫培养法在原位沉积物芯上研究了摇蚊幼虫（Prosilocerus akamusi）生物扰动对沉积物磷（P）迁移性的影响，为期 34 天。使用高分辨率透析（HR-Peeper）和扩散梯度薄膜（DGT）技术记录了沉积物中可溶性和 DGT 不稳定 P 以及铁（Fe）浓度的细尺度变化。幼虫将上层水灌入其洞穴中，显著增加了沉积物中的氧气穿透深度（OPD）和氧化还原状态（Eh）。此外，随着幼虫生物扰动沉积物中 OPD 和 Eh 的增加，可溶性和 DGT 不稳定 P 和 Fe 的浓度降低。在实验的第 15 天，Prosilocerus 组中 SRP、可溶性 Fe 和 DGT 不稳定 P 的平均浓度下降最大，下降幅度超过对照组的一半。此外，DGT 不稳定 P 浓度的二维测量显示，DGT 不稳定 P 在幼虫洞穴周围明显减少。DGT 诱导的沉积物通量（DIFS）模型也表现出更长的响应时间（420 秒）和更高的磷吸附速率（0.002 秒），而在生物扰动沉积物中比在对照沉积物中分别为 116 秒和 0.009 秒。DGT 不稳定 P 和 DGT 不稳定 Fe 之间显示出显著的相关性。我们得出结论，Fe(II)氧化及其增强的吸附是导致沉积物中可溶性和 DGT 不稳定 P 减少的主要机制。
