【作者】 刘培怡；

【导师】 李北罡；

【作者基本信息】 内蒙古师范大学 ， 环境科学， 2011， 硕士

【摘要】 生源要素磷(P)在自然界中的循环主要是通过固体颗粒物与陆河海水体间的相互作用来完成,该过程对维持水体正常生态平衡起着举足轻重的作用,因此水体颗粒物对实现磷的地球化学循环具有重要影响。本文主要选取黄河上游不同段位表层沉积物,进行了以下两大方面研究工作：①沉积物样中磷的各种赋存形态及总磷(TP)、无机磷(IP)、有机磷(OP)、总氮(TN)、总碳(TC)的含量和分布特征,七种形态磷的含量与粒径的相关性分析；重点估算了沉积物中潜在的生物可利用磷(BP)的量；②沉积物对磷的吸附特征及吸附/解吸平衡质量浓度(EPC0值)。所得结论如下：1黄河上游表层沉积物中各形态磷、TP、TN、TC及BP的含量分布(1)采用改进的七步连续提取法将沉积物中磷的形态分为七种,即：可交换态磷(Ex-P)、铝结合态磷(Al-P)、铁结合态磷(Fe-P)、闭蓄态磷(Obs-P)、自生钙结合磷(Ca-P)、原生碎屑磷(De-P)、有机磷(OP)。在黄河上游所有不同粒径沉积物的各种形态磷中,De-P和Ca-P是沉积物磷的主要赋存形态,其含量范围分别为139.08～482.89 mg·kg-1和40.30～125.55 mg·kg-1,二者共占TP含量约86.72%；OP含量范围为6.14～36.74 mg·kg-1,占TP的3.90%;Ex-P、Al-P和Fe-P平均含量分别为7.53 mg·kg-1、25.85 mg·kg-1和5.05 mg·kg-1,三者共占TP含量约9.23%；在各形态磷中,Obs-P含量最低,平均值为0.64 mg·kg-1,约占TP的0.15%。其中Ex-P和Fe-P含量在黄河源头玛多段最高,Ca-P和De-P含量在青海贵德段最高,Al-P含量在内蒙古包头段最高,Obs-P含量在宁夏中卫段最高,而OP含量在内蒙古河口段最高。(2)样品中各种形态磷的含量分布直接与取样点及沉积物粒径有关。同一沉积物中不同形态磷含量随粒径的变化而不同；同一形态磷含量在不同沉积物中与粒径的关系也有所不同,如宁夏中卫段Ex-P含量随粒径的减小而降低,其余段位Ex-P含量随粒径的减小而增大。其中De-P与TP有极显著的正相关,因此De-P是TP的最大贡献者。(3)TP.TC和TN的平均含量分别为1249.24 mg.kg-1、62.14 mg·kg-1和324.98mg·kg-1。以上各项含量分布均随取样点的不同而异,但TC和TN最高值均出现在玛多段。(4)沉积物中潜在的生物可利用P(bioavailable phosphorus, BP)的量至少约占TP的5.91%～30.17%。根据每年黄河向渤海的输沙量(约按10亿吨计)可估算出泥沙入海后可提供潜在的BP的量约为3.21～8.92万吨。2黄河上游表层沉积物对磷的吸附特征研究探讨了黄河上游表层沉积物对磷的吸附动力学及其影响因素、等温吸附行为、吸附/解吸平衡质量浓度(EPC0值)及水体pH值对吸附的影响。研究结果如下：(1)吸附动力学研究表明所研究沉积物在相应上覆水体中对磷的吸附具有相同的变化趋势,即在0～8 h内进行较快,8～48 h内吸附速率逐渐变缓,48 h时基本达到吸附平衡,但对磷的吸附量随沉积物的不同而异。沉积物对磷的吸附动力学直接受时间、P初始浓度、沉积物含量和溶液pH值的影响。不同沉积物在不同起始P浓度下对P的吸附动力学均符合二级吸附动力学模型及Weber-Morris扩散方程,求得二级吸附速率常数和扩散速率常数分别在10.99～229.29 g·mg-1·h-1和0.0003～0.0020 mg/(g·h1/2)之间,吸附过程由P在沉积物内扩散控制。(2)沉积物对磷的等温吸附行为既很好的符合线性方程和Freundlich模型,也较好的符合Langmuir模型,不符合Temkim模型,但实验数据经此拟合后的变化趋势符合指数方程,相关性极好。不同pH值对沉积物吸附磷均有一定影响。当平衡质量浓度相同时,除青海贵德、内蒙古包头段外,其余各点样品均在接近中性时吸附量最大,pH值在增大或减小的条件下吸附量均表现为下降,不同pH值下各段位沉积物对磷的等温吸附行为均符合线性方程、Langmuir模型、Freundlich吸附及指数方程,并达到显著相关,不符合Temkim模型。(3)当水体中P浓度很低时,沉积物对磷的吸附量与P初始质量浓度之间呈很好的线性关系,由此获得了不同沉积物对磷的吸附/解吸平衡质量浓度(EPC0值)范围为0.002mg·L-1～0.013 mg·L-1,该值均高于目前上覆水体中P浓度,故沉积物有向上覆水释磷的趋势。更多还原

【Abstract】 Phosphorus (P) is a vital element and its cycling in natural work(?) achieved by the interaction between particulate matters and water among earth-river-sea, which is significant to keep the balance of river-sea ecosystem therefore particulate matters in the waters have very important influences for phosphorus to achieve the cycle of the earth and chemistry. In this papo(?) surface sediments from the upper reaches of the Yellow River were studied by following parts:①The contents and their distribution characteristics of all kinds of phosphorus forms and totle phosphorus(TP), inorganic phosphorus(IP), organic phosphorus(OP), totle nitrogen(TN), totle carbon(TC) were investigated in the sediments, and the relativity between their contents and grain sizes was analyzed; The contents of potential bioavailable phosphorus(BP) in the sediments were estimated;②P adsorption characteristic in sediments and EPCo of P adsorption/desorption were researched. The results have shown that:1 Contents and distribution of TP, all foms phosphorus, TN, TC and BP(?) the sediments from the upper reaches of the Yellow River(1) Seven forms of P in sediments were investigated by using the improved seven-step sequential extraction method and distinguished (?) following:exchangeable+loosely bound P(Ex-P), aluminum-bound P(A1-P), iron-bound P(Fe-P), obstinate-bound P(Obs-P), anthigenic+biogenic apatite +calcium carbonate-bound P(Ca-P), Detrital apatite+other remaining inorganic P (De-P), organic P(OP). In all samples with different particle sizes from the upper reaches of the Yellow River, De-P and Ca-P were the major components and their contents ranged from 139.08 mg-kg-1 to 482.89 mg-kg-1 and from 40.30 mg-kg-1 to 125.55 mg-kg-1,respectively, both of them occupied about 86.72% of TP; OP contens ranged from 6.14 mg-kg-1 to 36.74 mg-kg-1 and was 3.90% of TP; the mean of Ex-P, Al-P and Fe-P was 7.53 mg·kg-1,25.85 mg-kg-1 and 5.05 mg-kg-1, respectively, all of there were about 9.23% of TP; Obs-P contents were the lowest in all form P, the average was 0.64 mg-kg-1, about 0.15% of TP; The maximum contents of Ex-P, Fe-P were appeared in sediments of Qinghai Maduo that is the source of the Yellow River, the maximum value of Ca-P, De-P were appeared at Qinghai Guide, the maximum contents of Al-P, Obs-P and OP were appeared in sediments of Inner Mongolia Baotou, Ningxia Zhongwei and Inner Mongolia Hekou, respectively.(2) The content distribution of various form P in studied sediments correlated with the grain size and the sampling sites directly. The relations between various form P of one kind of sediment and grain sizes and between one form P of different sediments and grain sizes were different, for example, the Ex-P contents in sediments of Zhongwei reduced with grain size minishing and in the other sediments were opposite. The positive correlation between the contents of De-P and TP was very remarkable, so De-P was the major contributor to TP.(3) The mean of TP.TC and TN was 1249.24 mg-kg-1、62.14 mg-kg-1 and 324.98 mg-kg-1, respectively. Their content distributions changed with the sampling sites. The maximum values of TC and TN all appeared in Maduo.(4) In all studied samples, the contents of potential bioavailable phosphorus (BP) were at least about 5.91%～30.17% of TP. Based on the quantity of paticulates transported from the Yellow River to the Bohai Sea and the above results, the amount of potential BP was estimated approximately 32.1～89.2 thousand ton.2 Adsorption charicterristics of P onto sediments from the upper reaches of the Yellow RiverP adsorption kinetics and its influence factors, adsorption isotherm behavior and adsorption/desorption EPC0 and the influence of pH on adsorption in surface sediments from the upper reaches of the Yellow River were researched and the results indicated that:(1) The research on P adsorption kinetics indicates that the adsorption of sediments to P in their overlying water had same tendency, it was faster in 0～8 h, gradually slower in 8～48 h and after 48 h was basically balanceable, but adsorption amount of P on various sediments were different. Time, the initi(?) P concentration, sediment concentration and PH in solution had direct impac(?) on P adsorption. At different initial P concentration, P adsorption kinetics on(?) different sediments all followed second-order adsorption kinetic model and Webber-Morris diffusion equation which second-order adsorption rate constants and diffusion rate constants obtained were in range of 10.99～229.29 g·mg-1·h-1 and 0.0003～0.0020 mg/(g·h1/2), respectively. The P adsorption process was controlled by the intra-particle diffusion.(2) Adsorption isotherms of sediments to P indicated that isotherms for P sorption were well fitted to linear equation and Freundlich equation, as well as Langmuir equation, not fitted to Temkim equation, but the change tendency of experiment data fitted by Temkim equation were well fitted index equation and the relativities were very remarkable. Different pH values had different impacts on P adsoption isotherms. When equilibrium quality concentrations were the same, the absorption amount of phosphate onto other sediments was biggest near neutral condition, and was descended in acid and alkaline conditions except Guide or Baotou.(3) The correlation between the adsorption amount of sediments to P and initial P concentration had good linear relationship when P concentration in the overlying water was very low. According to the linear equation, adsoption-desorption equilibrium concentrations(EPC0 value) of different sediments to P were found and ranged from 0.002 mg·L-1 to 0.013 mg·L-1, which were all higher than P concentrations in waters, so the sediments had the trend of releasing P to overlying waters.更多还原