曹 琳，吉芳英，林 茂，王图锦，黎 司

重庆大学三峡库区生态环境教育部重点实验室，重庆 400045

有机质对三峡库区消落区沉积物磷释放的影响

曹 琳，吉芳英*，林 茂，王图锦，黎 司

重庆大学三峡库区生态环境教育部重点实验室，重庆 400045

以三峡库区丰都消落区沉积物为研究对象，通过分析沉积物中磷的赋存形态，以及去除轻组有机质沉积物和沉积物矿物质对磷的吸附等温曲线，揭示了磷的赋存形态及释放与有机质的关系.结果表明:消落区本底土壤较沉积物w(总磷)，w(有机磷)及w(活性磷)更高，首次覆水时更具潜在释磷风险，夏季出露期有利于沉积物有机质和有机磷积累，沉积物有机质矿化分解对磷释放起促进作用，沉积物中w(有机质)与w(有机磷)呈显著正相关，与w(无机磷)呈负相关.关键词:三峡库区;磷;有机质;沉积物;释放

Abstract:Taking the sediments in the fluctuating zone of the Fengdu section in the Three Gorges Reservoir Area as the study object，phosphorous forms in the sediments and adsorption isotherm curves of phosphorous to m ineral sediments and light fraction organic matter-removed sediments were analyzed.This study reveals the correlation between forms and release laws of phosphorous and organic matter.The results show:total phosphorous(TP)content，organic phosphorous content and active phosphorous content in background soils are higher than their corresponding contents in sediments in the fluctuating zone.In addition，the very first submersion posesmore potential risk of phosphorous release.The exposing state in summer is conducive to accumulation of organic matter and organic phosphorous in the sediments.Decomposition of organic matter boosts the release of phosphorous. Moreover，organic matter content in sediments show a significant positive correlation with organic phosphorous content，while a negative correlation with inorganic phosphorous content.

Keywords:Three Gorges Reservoir Area(TGRA);phosphorous;organic matter;sediments;release

根据三峡水库“蓄清排浊”的运行方案，库区周边已形成垂直距离30 m，面积440 km2的反季节消落区［1］.消落区表层沉积物是磷元素积累和释放的重要且活跃场所［2-4］.现有研究［5-7］表明沉积物有机质是湖库重要的磷源，其矿化降解过程中释放的营养物质可以造成严重的水体富营养化.MORRIS等［8］模拟研究沉积物剖面发现，有机质矿化主要发生在表层 2 cm厚的沉积物中; GACHTER等［9］经10年湖底曝气研究发现，由于湖底富集的有机质大量矿化释放导致上覆水体中ρ(磷)的降低效果不明显;王圣瑞等［10-11］研究长江中下游浅水湖泊发现，沉积物对磷的吸附解吸平衡浓度与其……