骆马湖泥-水界面磷铁硫原位同步变化特征

利用薄膜梯度扩散（DGT）原位采样装置获取了骆马湖全湖8个典型湖区泥-水界面（SWI）活性磷（P）、铁（Fe）、硫（S）垂向分布信息，据此定量估算三者交换通量.结果表明，骆马湖沉积物剖面P、Fe、S浓度范围分别为0~2.05，0~11.10和0.01~0.63mg/L，并在微小尺度呈高度空间异质性.在水平方向上活性P、Fe主要表现为西北湖区高于东南湖区，而活性S则未表现出明显的分布规律；就垂直剖面而言，活性P、Fe、S自界面向下呈升高趋势，并在60mm深度内出现峰值，且活性P和Fe剖面呈明显的同步变化特征；活性P、Fe在多数点位具有显著的正相关性（r>0.65，P<0.01），且各采样点沉积物中的总铁与总磷比值w（∑Fe）/w（∑P）]均高于15，这表明Fe的地球化学循环过程对于骆马湖内源磷释放起重要控制作用；8个采样点样品中活性P、Fe、S交换通量分别为0.066~0.698，1.671~5.592和0.007~0.071mg/（m²·d），表明P、Fe、S由沉积物向水体释放.西北湖区表现出较高的P通量和活性P浓度，这可能会增加南水北调过程中水质污染的风险，应予以重视.以上结果支持了P、Fe耦合释放机制，明确了骆马湖SWI的活性P、Fe、S迁移特征.

In situ and combined variations of phosphorus,iron and sulfur across the sediment-water interface of Lake Luoma

This study firstly obtained 8 typical profiles of labile phosphorus (P), iron (Fe), and sulfur (S) in the sediments of Lake Luoma using the in situ, diffusive gradients in thin films (DGT) technology, and then quantitatively calculated the combined fluxes of P, Fe and S across the sediment-water interfaces (SWI). Our results demonstrated that highly heterogeneous distributions of DGT-measured labile P, Fe and S in the sediment profiles, with the concentration ranges from 0 to 2.05mg/L, 0 to 11.10mg/L and 0.01 to 0.63mg/L, respectively. Generally, the concentrations of labile P and Fe in the northwest lake area were higher than those in the southeast lake area, while the variations of labile S showed no significant regularity. For all the profiles collected, the variations of labile P, Fe, and S exhibited a similar shape reflected by downward increases in concentration with sediment depth, and appear concentration peaks were observed within 60mm depth. Moreover, there was a significant positive correlation(r>0.65, P<0.01) between labile P and Fe, and the ratio of total iron to total phosphorus w(∑Fe)/w(∑P)] was higher than 15, which disclosed that the geochemical cycle of Fe played an important role in controlling the release of endogenous phosphorus in Lake Luoma; The fluxes of labile P, Fe and S across the SWI were 0.066~0.698mg/(m²·d), 1.671~5.592mg/(m²·d) and 0.007~0.071mg/(m²·d), respectively, indicating that P, Fe and S of Lake Luoma were released from sediments to water. It may increase the risk of water pollution during the South-to-North Water Diversion and accordingly should be taken seriously. The above results supported the coupled release mechanism of P and Fe, and clarified the migration characteristics of active P, Fe and S in SWI of Lake Luoma, providing reference and theoretical basis for water quality control of Luoma Lake.