微生物对冰封期湖泊沉积物中有机磷降解释放的影响

以寒旱区湖泊乌梁素海为研究对象,以有机磷降解过程中的形态转化为主线,探讨了冰封期内底物添加与灭菌处理对有机磷释放特征的影响.结果表明,180 d冰封期内,灭菌处理(T_N)上覆水中可溶性总磷酸盐(DTP)和可溶性正磷酸盐(DIP)及可溶性有机磷(DOP)的质量浓度均高于底物添加处理(T_M),揭示T_M体系中厌氧微生物的同化利用降低了上覆水中磷的质量浓度;同时微生物驱动下铁的异化还原作用也是影响水-沉积物界面有机磷释放的重要机制.释放周期内,沉积物中活性有机磷(LOP)、总活性磷(TLP)的含量均减少;T_M体系的中等活性有机磷(MLOP)含量先减少后增加,非活性有机磷(NLOP)的含量先增加后减少;T_N的MLOP含量波动性增加,NLOP的含量波动性减少.释放初期(0~60 d),T_M的MLOP含量高于T_N,而NLOP的含量低于T_N;释放中末期(60~180 d),T_M的MLOP含量低于T_N,而NLOP的含量高于T_N.揭示释放中沉积物MLOP与NLOP之间存在相互转化的可能性.释放过程中,T_M沉积物有机磷的相对含量降低,无机磷的相对含量增高,呈现有机磷向无机磷转化的趋势,沉积物有机磷约有6.1%转化为无机磷,揭示了冰封期内,微生物可加速沉积物有机磷向无机磷的转化,提高了磷的生物可利用率,增加了沉积物磷向上覆水释放的风险.

Impacts of Microorganisms on Degradation and Release Characteristics of Organic Phosphorus in Lake Sediments During Freezing Season

Organic phosphorus (OP) has been considered as an important pool for bioavailable phosphorus. In this work, impacts of microorganisms on the degradation and release of OP in sediments from Lake Wuliangsuhai during freezing season were investigated using chemical sequential extraction methods. The results showed that the concentrations of dissolved total phosphorus (DTP), dissolved inorganic phosphorus (DIP) and dissolved organic phosphorus (DOP) in overlying water of the sterilization (T_N) treatments were higher than those of the substrate addition (T_M) treatments, indicating that the assimilation of anaerobic microorganisms and the disassimilation reduction of iron driven by microorganisms were the main mechanisms govening OP behavior and process across the water-sediments interface. The concentrations of labile OP (LOP) and total labile phosphorus (TLP) decreased during the releasing period. During the first 60 days, the concentrations of moderately labile OP (MLOP) of T_M treatments decreased, while those of the nonlabile OP (NLOP) increased. During 60-180 days, the MLOP concentrations of T_M treatments were found increasing, while those of NLOP decreased. During the beginning period (0-60 d), the concentrations of MLOP of T_M treatments were higher than those of T_N treatments, while the NLOP concentrations were lower than those of T_N treatments; and these trends were reversed during 60-180 days. These trends revealed the possibility of transformation between MLOP and NLOP during the releasing process. Furthermore, the percentage of OP was found decreasing, while inorganic phosphorus (IP) of T_M treatments increased, which indicated the transfromation trend from OP to IP (about 6.1% of OP was transformed to IP) in sediments. On the basis of this work, it can be conclueded that microorganisms can improve the transformation from OP to IP elevating the bioavailability and contribution of OP in the eutrophication process of lakes.