【作者】 蒋疆；

【导师】 王果；

【作者基本信息】 福建农林大学 ， 土壤学， 2000， 硕士

【摘要】 研究了由草炭提取的胡敏酸（HA）、富里酸（FA）、水溶解态有机物质（WSOM）的基因特征，分子量特征及其与Cu²⁺、Cd²⁺、Pb²⁺、Zn²⁺四种金属离子之间的络合稳定性和配位数，采用化学常量分析法测定其主要含氧功能基组成，以固态¹³C NMR对HA、FA及WSOM的结构特征进行描述，用水相凝胶色谱法测定三种有机质样品的分子量及分子量分布。研究结果显示HA分子最大且含有大量的长链烷烃，而FA分子小得多，结构以碳水化合物及多糖为主，WSOM的分子量略低于FA，结构与FA相近。FA的总酸度和羧基含量明显高于HA和WSOM，而WSOM略低于HA。 对三种有机质样品与四种重金属离子的红外光谱研究证实除—COOH外参与络合重金属阳离子的还有—OH和C＝O。但仅仅从对称及反对称伸缩振动的频率还不能确定金属离子与含氧官能团键合是共价性还是离子性。胡敏酸酸、富里酸和Cu²⁺、Cd²⁺、Pb²⁺、Zn²⁺四种金属离子络合能力依次为：Cu²⁺＞Pb²⁺＞Cd²⁺＞Zn²⁺，但WSOM和Cu²⁺、Cd²⁺、Pb²⁺、Zn²⁺四种金属离子络合物的红外光谱还不能揭示哪种金属离子具有最大结合倾向。 采用离子交换平衡法测定三种有机质样品与四种金属离子的络合配位数和稳定常数，得出如下主要测定结果； 络合配位数 络合稳定常数 结果表明：金属离子与有机质通常形成混合或多核络合物。随介质PH的增大，x、logK均有不同程度的增加。同一介质条件下logK：M—HA＞M—FA＞M—WSOM。更多还原

【Abstract】 Complexiation of heavy-metal ions by naturally occurring dissolved-organic-matter(DOM) is widely studied because this complexiationcan chang the transport pathways and toxicity of metal ions.The group characteristics, molecular weight of the DOM extracted from a peat,humic acid(HA),fulvic acid(FA) and water-soluble-organic-matter (WSOM),and the complexiation relationship between HA. FM WSOM and Cu2~~ Zn2~~ Pb2~~ Cd2~ were studied. The oxgen- containing functional group of HA FA WSOM was identified by direct chemical analytical methods .A solid state ?C-NMR was done to describe the structure of the DOMs.An aqueous gel chromatography was developed for determination of molecular and molecular weight distribution of the DQMs.The results of the studies showed that HA was of higher molecular weight and contained a large amount of alkly carbons in its structure,while FA was of lower molecular weight and contained a large amount of polysaccharide carbons.Although the molecular weight of WSOM was a little lower than that of FA ,the structure of WSOM was similar to that of FA.The contents of total acid group and carboxyl group in fulvic acid were far higher than that of l-IA,while that of total acid group and carboxyl group of WSOM was olower thanthat of HA. An infrared spectroscopic investigation of the complexes of four metal ions with DOMs demonstrated the participation of 桹H and C0 groups in addition to 桟OOK in binding of heavy- metal cations.However the nature of the metal-carboxylate linkages cannot be accurately determined from the positions of antisymmetric and symmetric carboxylate stretching vibrations .The complexiation tendency of the four divalent cations with HA and FA, revealed by the infrared spectroscopic spectrum, decreased in the order of Cu2~>Pb2~>Cd2~>Zn2~,while the tendency of the ions with WSOM was not clearly revealed by the IR method. Ion-exchange equilibrium method was used to determine the stability constants of the ion- DOM complexes formed by four different ions under two PH conditions.The results were as follows: at 10.l,PH=3.5,the orders of the coordination numbers x were: M-HA: Cu2~ (1.21) >Zn2~ (0.90) >Pb2~ (0.85) >Cd2~ (0.42): M-FA Cu2~ (0.99) >Pb2~ (0.93) >Cd2~ (0.59) >Zn2~ (0.46); M-WSOM: Cu2~ (0.92) >Pb2~ (0.59) >Zn2~ (0.33) >Cd2~ (0.18). the orders of stability constants were: M-HA Cu2~ (4.81) >Pb2~ (3.76) >Zn24 (3.72) >Cd2~ (1.91); M-FA: Cu2~ (3.16) >Pb2~ (2.96) >Zn2~ (1.72) >Cd2~ (1.46); M-WSOM Cu2~ (3.31) >Pb2~ (1.57) >Zn2~ (0.73) >Cd2~ (0.37). At 10.1,PH=5.0, the orders of the coordination numbers x were: M-HA: Cu2~ (1.76) >Zn2~ (1.28) >Pb2~ (1.01) >Cd2~ (0.64); 47 M-FA: Cu24 (0.98) >Pb24 (0.90) >Cd24 (0.80) >Zn2~ (0 .48): M-WSOM: Cu24 (1.42) >Pb24 (0.65) >Cd24 (0.53) >Zn24 (0.34)~ the orders of stability constants were: M-HA Cu2~ (6.48) >Pb24 (4.45) >Zn24 (4.29) >Cd24 (2.36); M-FA: Cu24 (4.26) >Pb24 (3.12) >Cd24 (2.49) >Zn24 (1.75): M-WSOM Cu24 (4.71) >Pb24 (1.26) >Zn24 (0.79) >Cd24 (0.47)~ Metal ions and DOM usually formed mixed or plynuclear complexes.Under high PH condition,there was a marked increase in coordination numbers and stability constants.The stability constants Of ion-DOM under the same PH condition were: M-HA>M-FA>M-WSOM.更多还原