Jørgensen Charlotte, Jensen Henning S, Andersen Frede Ø, Egemose Sara, Reitzel Kasper
Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230, Odense M, Denmark.
J Environ Monit. 2011 Aug;13(8):2328-34. doi: 10.1039/c1em10202h. Epub 2011 Jun 24.
Orthophosphate monoesters often constitute a significant fraction of total phosphorus in lake sediments. The knowledge on the specific composition and recalcitrance of these compounds is however limited. The main aim was therefore to identify and quantify specific orthophosphate monoesters in sediment from 15 Danish lakes by solution (31)P NMR spectroscopy. The four most quantitatively important orthophosphate monoesters were myo-inositol hexakisphosphate (myo-IP(6)), scyllo-inositol hexakisphosphate (scyllo-IP(6)) α-glycerophosphate (α-GP) and β-glycerophosphate (β-GP). The compounds were identified in 9, 4, 8 and in all 15 lakes, respectively. In total these four components made up 46-100% of the orthophosphate monoester pool. The glycerophosphates (GPs) are most likely degradation products of phospholipids, created as an artifact by the alkaline extraction procedure used for (31)P NMR spectroscopy, while the inositol hexakisphosphates (IPs) are naturally occurring compounds. There was a significant positive correlation between myo-IP(6) and total aluminium in the sediment and a negative correlation between myo-IP(6) and lake water pH, suggesting that myo-IP(6) is stabilized in the sediment by adsorption at slightly acidic or neutral conditions. In three lakes, the depth distribution of the orthophosphate monoesters was investigated. The content of scyllo-IP(6) and myo-IP(6) was constant with sediment depth in two of the lakes while the content of myo-IP(6) decreased with depth in one of the lakes. In all cases the IPs seem to be preserved with sediment depth to a higher extent than the orthophosphate diesters and especially the GPs suggesting that IPs can be a sink for phosphorus in the lake ecosystem or at least delay P-recycling for years.
正磷酸单酯通常在湖泊沉积物中的总磷中占相当大的比例。然而，关于这些化合物的具体组成和难降解性的知识却很有限。因此，主要目的是通过溶液³¹P核磁共振光谱法鉴定和定量来自15个丹麦湖泊沉积物中的特定正磷酸单酯。四种在数量上最重要的正磷酸单酯是肌醇六磷酸（myo-IP₆）、scyllo-肌醇六磷酸（scyllo-IP₆）、α-甘油磷酸（α-GP）和β-甘油磷酸（β-GP）。这些化合物分别在9个、4个、8个和全部15个湖泊中被鉴定出来。总体而言，这四种成分占正磷酸单酯总量的46%-100%。甘油磷酸酯（GPs）很可能是磷脂的降解产物，是用于³¹P核磁共振光谱法的碱性提取过程产生的人为产物，而肌醇六磷酸（IPs）是天然存在的化合物。沉积物中myo-IP₆与总铝之间存在显著正相关，myo-IP₆与湖水pH之间存在负相关，这表明myo-IP₆在沉积物中通过在微酸性或中性条件下的吸附而得以稳定。在三个湖泊中，研究了正磷酸单酯的深度分布。在其中两个湖泊中scyllo-IP₆和myo-IP₆的含量随沉积物深度保持恒定，而在其中一个湖泊中myo-IP₆的含量随深度降低。在所有情况下，IPs似乎比正磷酸二酯尤其是GPs在沉积物深度中保存得更好，这表明IPs可能是湖泊生态系统中磷的一个汇，或者至少能使磷的再循环延迟数年。
