岱海沉积物氟化物赋存特征及其释放风险

为揭示岱海水-沉积物中氟化物的迁移转化规律，采用连续分级法研究了岱海间隙水，表层沉积物，柱状沉积物系统中氟化物的空间分布，赋存形态及释放风险.结果表明：岱海间隙水体中氟离子浓度平均值为（4.82±0.06）mg/L，显著高于地表水V类阈值（1.5mg/L），并与上覆水中氟离子浓度（4.77±0.04）mg/L达到相对稳定平衡状态.表层沉积物总氟化物含量均值为（934.13±36.79）mg/kg，其中水溶态，可交换态，Fe/Mn结合态，有机束缚态和残渣态氟化物含量均值分别为（34.39±1.69），（7.11±0.93），（3.07±0.50），（11.97±0.79）和（934.13±36.79）mg/kg；柱状沉积物水溶态，可交换态，有机束缚态氟化物含量随沉积物深度的增加呈下降趋势，并在40cm以下基本稳定；而Fe/Mn结合态氟化物在表层含量较低，在25cm后逐步稳定.多元回归分析可知，岱海沉积物中水溶态，可交换态氟化物含量与间隙水氟离子浓度呈显著正相关，且具有较强的迁移能力；SAC（稳定度）风险评估表明，表层沉积物中SAC范围在55.53%~69.52%，平均值为60.63%，处于极不稳定状态，且SAC从表层向下20cm呈逐步降低的趋势，间接反映出近年来可提取态氟化物富集明显，处于较强的释放风险状态.

Occurrence characteristics and release potential of fluoride in sediment of DaiHai Lake

In this paper, we applied a continuous fractionation method to analyze the spatial distribution, occurrence characteristics and release of fluorine in the interstitial water, surface sediments and core sediments of DaiHai Lake, with aiming to reveal the migration and transformation of fluorine in the water-sediment of DaiHai. Investigation results showed that the average of the fluoride ion concentration in the interstitial water was (4.82±0.06)mg/L, which largely exceeded the threshold in National surface water standard criterion Ⅴ(1.5mg/L). Moreover, the relative concentration of fluoride ion between the interstitial water and the overlying water(4.77mg/L) remained stable. The average of the total fluoride in the surface sediments was (934.13±36.79) mg/kg, including (34.39±1.69)mg/kg water-solution fluoride, (7.11±0.93)mg/kg exchangeable fluoride, (3.07±0.50)mg/kg Fe/Mn bound, (11.97±0.79)mg/kg Organic bound and (934.13±36.79)mg/kg residual fluoride. In the core sediments, the fluoride ion concentrations of water-solution, exchangeable, Organic bound reduced with sediment depth increasing, and kept stable under 40cm; however, the fluorine of Fe/Mn bound was low in the surface and became stable under 25cm. Depending on the multiple regression analysis, both the amount of the water-solution fluorine and exchangeable fluorine of the sediment had much positively correlated with the fluorine in the interstitial water, and the fluorine had a strong migration ability. The stability risk assessment indicated that the range of SAC in the surface sediments was between 55.53%~69.52%, with the average being 60.63%, but in a largely unstable state. In addition, the SAC would decrease from the surface down 20cm, which indirectly reflected that the concentration of extractable fluoride had been obvious in recent years, with strong releases risk.