【作者】 李辉；

【导师】 潘学军；

【作者基本信息】 昆明理工大学 ， 环境工程， 2012， 硕士

【摘要】 上世纪80年代以来,滇池逐渐成为我国污染最为严重的湖泊之一,严重的内源污染导致滇池自净能力丧失是滇池治理难点所在。沉积物是湖泊生态环境演变历史的记录器,研究滇池柱状沉积物中氮污染物赋存形态及分布特征,是估算滇池沉积物中氮污染负荷和预测沉积物-水界面氮污染物迁移行为的基础,对了解湖泊的历史污染状况、污染物来源追溯、沉积环境的演变与推测等都有着重要意义。本研究测定了滇池外海11根柱状沉积物(0-50cm)中氮的总量以及不同赋存形态。结果表明,与其他湖泊相比,滇池沉积物中氮含量相对较高,平均含量达到了2319.20±387.27mg/kg。其中,Trans-N是TN的主要组成部分,平均含量为1230±148.52mg/kg; SOEF-N是Trans-N的主要组成部分,四种可转化态氮的含量大小顺序依次为SOEF-N>WAEF-N> SAEF-N>IEF-N; WAEF-N是TN中对富营养化贡献最大的形态。在平面分布上,本文按照污染物含量水平将滇池划分为北部、中部和南部三个区域。从TN含量来看,分布特征是南部>北部>中部；而按照Trans-N含量来看,则是北部>南部≈中部,综合推断可以得出,三个区域氮污染程度依次是北部>南部>中部。在纵向分布上,TN分布特征为在0-5cm沉积物中TN含量相对较小,5-15cm沉积层的TN含量相较于其他沉积层明显偏高；15-35cmTN含量有些波动,但幅度较小；而35-50cm沉积层TN含量变化很小；IEF-N的含量一直处于较低水平,随深度变化不大；WAEF-N含量在0-5cm沉积层较高,5-15cm沉积层相较0-5cm则有了明显降低,15cm以下WAEF-N含量随深度基本上变化不大；SAEF-N含量在0-5cm沉积层较低,5-15cm沉积层出现明显上升,15-50cm沉积层SAEF-N含量则相对稳定；SOEF-N的分布特征是在0-10cm沉积层含量很低,10-20cm沉积层开始显著上升,20-50cm沉积层则变化不大。在上述研究基础上,本文估算了滇池氮污染负荷及其生物可利用性：滇池外海0-15cm沉积层中TN负荷达到45353.6吨,其中IEF-N为4125.3吨,WAEF-N为6680.5吨,SAEF-N为3623.9吨,SOEF-N为9926.3吨；可转化态氮为24356吨,不可转化态氮为20997.6吨；生物可利用性氮含量约为14429.7吨,约占TN含量的31.8%。而不同沉积层估算结果显示,10-15cm沉积层TN负荷最高,表明对应的沉积年代(约为1972-1988年)是滇池污染物大量输入的时期,这较好地揭示了滇池的污染历史。本文还结合牛栏江补水工程有关数据,预测了实施补水工程对滇池沉积物-水界面氮污染物的迁移行为及其对水质的影响。更多还原

【Abstract】 Dianchi Lake has been one of the most eutrophic lakes in China since1980s. It’s a hard problem for the control of Dianchi Lake eutrophication that the lake was totally deprived of self-purification under the severely internal pollution for a long time. The form and distribution of nitrogen in sediment are the basis for estimation of internal nitrogen load and prediction on the transfer behavior of nitrogen at the sediment-water interface, it’s very important for learn about the pollution situation, trace the pollutant source, and predict the trend of deposition evolution, because the sediment is a recorder of the evolution of lake’s ecological environment.The content of total nitrogen and various nitrogen form in eleven sediment cores(0-50cm) sampled in the Waihai section of Dianchi Lake were measured in the research. It was shown that the content of TN was relative higher than the other domestic and foreign lakes’. The average content of TN in all the samples was2319.20±387.27mg/kg. Trans-N was the main part of TN and the SOEF-N was the main form of Trans-N, the average content of Trans-N was1230±148.52mg/kg. The order of the content of four transferrable nitrogen form in the sediment was SOEF-N>WAEF-N>SAEF-N>IEF-N; and the WAEF-N made the most contribution to lake eutrophication than the other nitrogen forms’.Dianchi Lake was divided into three part by the content of TN to study the nitrogen’s horizontal distribution:northern lake, central lake and southern lake. The order of the content of TN in this three part was southern>northern>central. However, the order of Trans-N’s content was northern> southern≈central, and the nitrogen pollution level was northern> southern> central in order from on a whole.The vertical profiles of TN and various nitrogen form are as follows:the content of TN was relative lower at0-5cm, and increased to the highest level at5-15cm in the most of sediment cores, and then changed little with the depth. The contents of IEF-N at different depositions were always low; the content of WAEF-N was relative high at0-5cm, and decreased significantly at5-15cm, then changed a little with the depth; the content of SAEF-N was relative low at0-5cm and increased sharply at5-15cm, then remained stable below; the content of SOEF-N was very low at0-5cm and increased sharply at10-20cm, the changed a little below.The internal nitrogen load and its bio-availability were estimated in the study. The weight of TN in the0-15cm deposition of Dianchi Lake was45353.6t, and IEF-N’s was4125.3t, WAEF-N’s was6680.5t, SAEF-N’s was3623.9t, SOEF-N’s was9926.3t; the Trans-N’s was24356t, FN’s was20997.6t. The weight of bio-available nitrogen was about14429.7t, accounted to TN31.8%averagely. The results were showed that the weight of TN at10-15cm, which was deposited in1972-1988approximately, was highest than the other depositions’, it was agreed with the contamination history of Dianchi Lake. In addition, the transfer behaviors of nitrogen at the sediment-water interface and the effect to the water caused by implementing the Diversion Project from Niulanjiang River to Dianchi Lake was predicted and analyzed.更多还原