State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, PR China.
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, PR China; College of Animal Science and Technology, Anhui Agricultural University, Hefei, 230036, PR China.
Environ Pollut. 2019 Mar;246:207-216. doi: 10.1016/j.envpol.2018.11.092. Epub 2018 Dec 5.
Dredging is frequently implemented for the reduction of internal nitrogen (N) and phosphorus (P) loadings and the control of eutrophication. Residuals during dredging activities and external pollution loadings after dredging both commonly contribute to influence the effectiveness of dredging and have been widely discussed. In the current study, the exchanges of N and P across the sediment-water interface (SWI) to these two factors were compared in a six-month field incubation experiment. The results showed that the continuous deposition of external suspended particulate matter (SPM) led ammonium nitrogen (NHN) and soluble reactive phosphorus (SRP) fluxes across the newly formed SWI to increase by factors of 4.16 and 12.71, respectively, while residual material caused the same fluxes to increase by factors of 2.06 and 5.06. Both the deposition of external SPM and the residual matter led to higher increase of the fluxes of P across the SWI than those of the fluxes of N across the SWI after dredging. The SPM easily adsorbed P in the water due to extensive adsorption of water soluble organic matter (consisting primarily of easily-decomposed humic-like substances), iron, and aluminum. However, the decomposition of organic matter in the SPM after the deposition on the dredged sediment accelerated the dissolution of redox-sensitive P and organic P across the SWI after dredging. Both the increase in the fluxes of N and P across the SWI would further increase the concentrations of N and P in the overlying water and thereby aggravate the eutrophication status in lakes. More frequent dredging operations might be necessary to reduce the fluxes of N and P from the sediment due to the continuous influence of the external SPM and the residual matter.
疏浚通常用于减少内部氮（N）和磷（P）负荷，并控制富营养化。疏浚活动中的残留物和疏浚后的外部污染负荷都会对疏浚效果产生影响，这一点已得到广泛讨论。在当前的研究中，通过为期六个月的野外孵化实验比较了这两个因素对底泥-水界面（SWI）N 和 P 交换的影响。结果表明，外部悬浮颗粒物（SPM）的连续沉积使新形成的 SWI 中铵氮（NHN）和可溶解性反应磷（SRP）通量分别增加了 4.16 倍和 12.71 倍，而残余物质使相同通量分别增加了 2.06 倍和 5.06 倍。外部 SPM 的沉积和残余物质的沉积都导致疏浚后 SWI 中 P 的通量增加高于 N 的通量增加。由于广泛吸附水溶性有机物（主要由易分解的腐殖质样物质组成）、铁和铝，因此，SPM 很容易吸附水中的 P。然而，沉积在疏浚底泥上的 SPM 中的有机物分解加速了疏浚后 SWI 中氧化还原敏感磷和有机磷的溶解。SWI 中 N 和 P 通量的增加会进一步增加上覆水中 N 和 P 的浓度，从而加剧湖泊的富营养化状况。由于外部 SPM 和残余物质的持续影响，可能需要更频繁地进行疏浚作业，以减少底泥中 N 和 P 的通量。
