以水稻土水溶性有机物(DOM)为对照,采用物理化学和光谱学实验研究了农业上常用有机物料:猪粪、绿肥和污泥DOM的理化性质差异.结果表明,水稻土、污泥、猪粪和绿肥DOM含量分别为122,23793,12904,380560mgC/kg.若施用等量有机物料,带入土壤的DOM量最多的应是绿肥.不同有机物料DOM中大分子组分含量高低顺序为:水稻土(51.08%)〉猪粪(41.25%)〉污泥(23.33%)〉绿肥(7.36%);而极性组分含量的顺序则相反,水稻土(10.71%)〈猪粪(31.04%)〈污泥(31.91%)〈绿肥(54.16%).DOM的生物可降解性与DOM的分子量、极性组分含量有关,分子量越大,极性组分含量越低,其越难被降解;反之则易.红外图谱显示DOM中存在醇及苯酚中的-OH、脂肪族饱和C-H、-NH4+、苯环C=C、-NH、多糖类、醇类、羧酸类与酯类C-O及苯环C-H等基团.其非极性基团与极性基团峰高之和的比值顺序显示土壤DOM非极性(1.21)〉猪粪DOM(1.12)〉污泥DOM(1.11)〉绿肥DOM(0.98),紫外图谱也证实了这一点.
Since environmental behavior and effect of dissolved organic matter depend mainly on its physicochemical properties,a series of physicochemical and spectroscopic experiments was employed to investigate fractionation and characterization of dissolved organic matter (DOM) derived from pig manure,sewage sludge and green manure,commonly applied in agriculture.The contents of DOM were 122,23793,12904 and 380560 mg C/kg for paddy soil,sewage sludge,pig manure and green manure,respectively.On the basis of the content of high molecule fraction,the DOM could be arranged in the following order:paddy soil (51.08%)pig manure (41.25%)sewage sludge (23.33%)green manure (7.36%).The tendency in content of polar fraction was reverse,i.e.,paddy soil (10.71%)pig manure (31.04%)sewage sludge (31.91%)green manure (54.16%).Biodegradability of DOM was related to its molecular weight and polar fraction.The higher the molecular weight was,the lower the content of polar fraction was,and the more difficultly DOM was biodegraded.FT-IR spectra indicated that DOM contains O—H (hydrogen-bonded alcohols,phenols and carboxylic acids),N-H (amines),aromatic ring,C—O (polysacchrides,carboxyl),and-CH2 function groups.The ratio of total peak heights of apolar function groups to those of polar function groups can be employed a token of apolarity of DOM.These ratios were arranged as paddy soil DOM (1.21)pig manure DOM(1.12)sewage sludge DOM(1.11)green manure DOM(0.98),and UV spectra of DOM further confirmed the order.