【作者】 张彬；

【导师】 郭劲松；

【作者基本信息】 重庆大学 ， 环境科学与工程， 2013， 博士

【摘要】 消落带作为水域和陆域生态系统的交错带，是生态系统中物质、能量输移和转化的活跃地带。在三峡水库周期性蓄水期间，淹没区土壤中的有机质（SOM）、氮、磷可以通过间隙水与上覆水进行物理的、化学的和生物的交换作用，影响上覆水的水质。因此，研究三峡水库消落带土壤有机质、氮、磷含量分布及其对水环境的影响对于阐明消落带土壤有机质、氮、磷的生物地球化学循环具有重要意义。本论文主要分析了三峡水库重庆主城-巫山区段消落带区域土壤理化特征，调查了消落带土壤有机质、氮、磷污染负荷时空分布特征，并利用收支平衡法构建了消落带土壤有机质、氮、磷的通量模型，利用简化后的模型估算了其在淹水和落干条件下的交换通量。同时结合三峡水库消落带的实际环境条件，在室内通过柱状实验模拟研究了有机质、氮、磷在不同环境条件下的扩散通量，结果如下：①三峡水库重庆主城-巫山段消落带土壤呈中性偏弱碱性；氧化还原电位偏低，整体上呈还原性；体积含水率较高。电导率的变化范围大部分在0.25-0.75ms/cm之间。不同采样点位消落带土壤电导率有一定差异；土壤粒径组成表现为粉砂粒>砂粒>粘粒；土壤化学组成主要由SiO₂构成，其占土壤化学组成比例为41.13%-74.88%。②不同土壤类型的有机质含量整体上表现为黄壤>冲积潮土>紫色土；不同流域的有机质含量整体上看来，三峡水库支流流域的有机质含量高于长江干流流域（甘井河流域除外）；2010年落干期消落带土壤有机质含量变化不大，2011年落干期消落带土壤有机质含量增加，2010年9月-2011年4月淹水期间消落带土壤有机质含量增加。③不同土壤类型的消落带土壤全氮（TN）含量表现为黄壤>紫色土>冲积潮土；不同流域全氮含量除龙溪河流域的全氮含量较高外，其余各流域无显著性差异；2010年落干期间，消落带土壤全氮含量变化不大，2011年落干期间消落带土壤全氮含量减少，2010-2011三峡水库蓄水期间，消落带土壤全氮含量减少。各形态氮整体上看来，在落干期间，可转化态氮（TF-N）、离子交换态（IEF-N）、弱酸可浸取态氮（WAEF-N）、铁锰氧化态氮（IMOF-N）、有机硫化物结合态氮（OSF-N）含量减少，但IEF-N和OSF-N整体下降幅度不大。非可转化态氮（NTF-N）含量在2010年落干期间增加，在2011年落干期间略有下降。淹水期间，TF-N、IEF-N、WAEF-N、IMOF-N和OSF-N含量增加，但OSF-N增加较少。而NTF-N含量有降低。TN与OSF-N的相关性最显著；WAEF-N与OSF-N相关性极显著；TN，OSF-N与SOM呈显著性正相关；全磷（TP）与IEF-N呈显著性正相关，与IMOF-N呈显著性负相关；pH与IEF-N呈显著性负相关，含水率与OSF-N呈显著性正相关。④研究范围内不同土壤类型全磷含量表现为黄壤>冲积潮土>紫色土。不同流域全磷含量除甘井河流域的全磷含量较高外，其余各支流流域全磷含量均低于长江干流流域。2010年落干期间，消落带土壤全磷含量变化不大。2011年落干期间，消落带土壤全磷含量增加。在2010年-2011年淹水期间，消落带土壤全磷含量减少。各形态磷整体上看，落干期间，除了2011年无机磷（IP）和有机磷（OP）含量有增加外，其余IP、铁铝结合态磷（Fe/Al-P）、钙结合态磷（Ca-P）和OP含量变化均不明显。淹水期间，IP、Fe/Al-P含量降低，而Ca-P和OP含量变化不明显。消落带土壤Ca-P与TP和IP相关性显著，Fe/Al-P和OP的相关性较显著，TN与OP，SOM与OP，SOM与Fe/Al-P之间具有显著相关性，OP同pH呈正相关，同氧化还原电位（ORP）呈负相关，消落带土壤磷的释放量和Fe/Al-P、OP呈显著性正相关。⑤消落带土壤磷的吸附主要发生在前12h，而后达到平衡；磷吸附速率主要受粒径小于50μm所占土壤组成比例的影响，其所占土壤组成比例越大，其磷的吸附速率越大。消落带土壤磷最大吸附能力变化范围在137.79-1975.59mg/kg之间，吸附效率的变化范围在47.34-230.88L/kg之间。⑥落干期交换通量估算结果为：全氮通量FN落干期=-43845t，全磷通量FP落干期=2025t，有机质通量FSOM落干期=42208t。淹水期交换通量估算结果为：全氮通量FN淹水期=48764t，全磷通量FP淹水期=7932t，有机质通量FSOM淹水期=-62117t。在一个淹水-落干周期中，消落带全氮含量减少了4919t，有机质含量增加了19909t，全磷含量减少了9957t。⑦消落带土壤TOC随着上覆水浓度增加先表现为源后表现为汇；随着pH增加交换通量呈倒“U”型；随着温度增加先表现汇后表现为源。消落带土壤氨氮、硝态氮、无机氮随着上覆水浓度增加实现由源到汇的转变；随着pH增加氨氮交换通量呈倒“U”型，硝态氮和无机氮实现由汇到源的转变；随着温度增加氨氮交换通量逐渐增加，硝态氮交换通量逐渐减少，无机氮实现由汇到源的转变。磷酸盐随着上覆水浓度增加先表现为源后变现为汇；随着pH增加磷酸盐交换通量呈“U”型；随着温度增加磷酸盐交换通量先表现为汇后表现为源。不同氮、磷含量条件下硝态氮和磷酸盐交换通量与土壤有机质含量呈显著正相关（P<0.05, R=0.75）。经过2003年-2011年几年的淹水落干，消落带土壤表现为有机质和全磷的释放源，全氮的累积汇。更多还原

【Abstract】 With regard to cohesion zone between the water and land area, complicatedmaterial and energy exchange and transformation processes would occur in thewater-level-fluctuating zone （WLFZ） of Three Gorges Reservoir （TGR）. Duringperiodical impoundment and flooding in TGR area, organic matter, nitrogen andphosphorous in the submerged soil of WLFZ can have physical, chemical and biologicalexchanges through interstitial water and overlying water. Therefore, the study of organicmatter, nitrogen and phosphorous distribution characteristics in the soil of WLFZ andtheir impact on water environment has great significance in illustrating biogeochemicalcycles. The physical and chemical indicators and the contents of organic matter,nitrogen and phosphorus in the center （from Wushan County to Chongqing city） ofWLFZ in TGR area are studied in this paper. Organic matter, nitrogen and phosphorusflux model by the break-even method are also built, and exchang fluxes in inundatedsoils and non-inundated soils of WLFZ using the simplied model are calculated. At last,combined with the actual environmental conditions of TGR, organic matter, nitrogenand phosphorus diffusion fluxes under different environmental conditions are simulatedby the experiment. The results are as follows:①The pH in the soils of WLFZ is mainly neutrality and alkalescency. ORP is low,showing reduction. Water content is high. Conductivity in the soils is vaired from0.25to0.75ms/cm, which is different among different sampling sites. The silt fraciton is themajor fraction in the study area. The clay fraction is the minor fraction. The chemicalcomposition of the soils in WLFZ is mainly made up of SiO₂, accounting for41.13%-74.88%of the total.②The average value of SOM in the soil of WLFZ could be ordered as yellowsoil>Fluvo-aquic soil>purple soil. The average contents of SOM in different basins areas follows: Tributaries basin>Yangtze River basin （excepting Ganjing River）. Duringnon-inundated period in2010, the content of SOM has little change. While Duringnon-inundated period in2011, the content of SOM has increased. During inundatedperiod from September2010to April2011, the concentration of SOM has increased,too.③The average value of TN was in the descending order of yellow soil>purplesoil>Fluvo-aquic soil. The average contents of TN in Longxi River are highest among different basins and there was no significant difference in the others. Duringnon-inundated period in2010, the content of TN has little change. While Duringnon-inundated period in2011, the content of TN has decreased. During inundatedperiod from2010to2011, the concentration of TN has also decreased. The contents ofvarious of nitrogen indicate that TF-N, IEF-N, WAEF-N, IMOF-N and OSF-N havedecreased during non-inundated, while IEF-N and OSF-N have declined a little. Thecontents of NTF-N have increased during non-inundated period in2010, but decreasedin2011. During inundated period, TF-N, IEF-N, WAEF-N, IMOF-N and have increased;NTF-N has declined. Positive correlation exists among the contents of TN, OSF-N andSOM, between WAEF-N and OSF-N, between TP and IEF-N, water content and OSF-N.TP is negatively correlated to IMOF-N, and pH is negatively correlated to IEF-N too.④The order of the average value of TP is as follow: Yellow soil>Fluvo-aquicsoil>Purple soil. In this study, the average contents of TP in different basins are asfollows: Yangtze River basin> Tributaries basin （excepting Ganjing River）. Duringnon-inundated period in2010, the content of TP has a little change. While Duringnon-inundated period in2011, the content of TP has increased. During inundated periodbeween2010and2011, the value of TP has decreased. The value of several of nitrogenindicates that IP, Fe/Al-P, Ca-P and OP have little change during non-inundated, whileIP and OP in2011have increased. During inundated period, IP and Fe/Al-P haveincreased; Ca-P and OP have changed a little. Positive correlation exists among thecontents of Ca-P, TP and IP, between Fe/Al-P and OP, among TN, OP and SOM, SOMand Fe/Al-P, between OP and pH. The contents of P released from the soils havepositive correlations with Fe/Al-P and OP. OP is negatively correlated to ORP.⑤The phosphate sorption on soils mainly occurs within12h and then reaches todynamic equilibrium. Its sorption rates are obviously affected by the volume percentageof fine particles less than50μm. The sorption rates increase rapidly with the percentageof fine particles increasing. The maximum phosphate sorption capacity of the soils isranged from137.79to1975.59mg/kg and the phosphate sorption efficiency of the soilsfrom47.34to230.88L/kg.⑥During the non-inundated period, the results of the flux of TN, TP and SOM inWLFZ are-43845t,2025t and42208t, respectively. During the inundated period, theresults of the flux of TN, TP and SOM in WLFZ are48764t,7932t and-62117t,respectively. After a cycle, the decrease of TN, TP content are4919t and9958t, theincrease of SOM content is19909t, and, respectively. ⑦TOC of the soil in WLFZ varied from source to sink with the concentration ofTOC in the overlying water increased; The exchange fluxes content of TOC expressedas inverted “U” curve under different pH; and the exchange fluxes value of TOC rangedfrom sink to source with the temperature increased. Ammonia, nitrate and inorganicnitrogen varied from source to sink under the different concentration of ammonia,nitrate and inorganic nitrogen in the overlying water, respectively; the exchange fluxescontent of ammonia described as inverted “U” curve and nitrate, inorganic nitrogenvaried from sink to source under different pH; the exchange fluxes value of ammoniaincreased, the fluxes value of nitrate decreased and inorganic nitrogen ranged from sinkto source with the temperature increased. Phosphate varied from source to sink underthe different concentration of phosphate in the overlying water; the exchange fluxescontent of phosphate characterised as “U” curve under different pH; and phosphateranged from sink to source with the increase of temperature. Positive correlation existsamong the contents of SOM and the exchange fluxes of nitrate and phosphate underdifferent content of nitrogen and phosphorus.更多还原