Plaza César, Hernández Diana, Fernández José M, Polo Alfredo
Centro de Ciencias Medioambientales, Consejo Superior de Investigaciones Científicas, Serrano 115 dpdo, Madrid, Spain.
Chemosphere. 2006 Nov;65(8):1321-9. doi: 10.1016/j.chemosphere.2006.04.026. Epub 2006 Jun 2.
The acid-base properties of humic acids (HAs) and fulvic acids (FAs) isolated from liquid swine manure (LSM), soils amended with either 90 or 150 m(3)ha(-1)year(-1) of LSM for 7 years, and the corresponding unamended control soil were investigated by a current potentiometric titration method. The non-ideal competitive adsorption (NICA)-Donnan model for proton binding by two classes of binding sites (i.e., carboxylic- and phenolic-type groups) was fit to titration data, and a set of fitting parameters was obtained for each HA and FA sample. The NICA-Donnan model was shown to describe with a great degree of accuracy the behavior of experimental titration datasets, and highlighted important differences in the acid-base properties of the HAs and FAs examined. When compared to the unamended soil HA and FA, LSM-HA and LSM-FA, had smaller acidic functional group contents, larger proton binding affinities of both carboxylic- and phenolic-type groups, smaller heterogeneity of carboxylic-type groups, and smaller, in the case of HA, or similar, in the case of FA, heterogeneity of phenolic-type groups. Amendment with LSM caused a decrease of acidic functional group contents and a slight increase of proton binding affinities of carboxylic- and phenolic-type groups of soil HAs and FAs. Further, LSM application induced a decrease of the heterogeneity of carboxylic-type groups, whereas appeared not to affect substantially the heterogeneity of phenolic-type groups of LSM-amended soil HAs and FAs. These effects were more evident for HAs than for FAs and tended to slightly increase with increasing LSM amendment rate.
采用电位滴定法研究了从液体猪粪（LSM）中分离出的腐殖酸（HAs）和富里酸（FAs）、用90或150立方米·公顷⁻¹·年⁻¹的LSM改良7年的土壤以及相应的未改良对照土壤的酸碱性质。将两类结合位点（即羧基和酚基类型基团）质子结合的非理想竞争吸附（NICA）-唐南模型拟合到滴定数据中，得到了每个HA和FA样品的一组拟合参数。结果表明，NICA-唐南模型能够高度准确地描述实验滴定数据集的行为，并突出了所研究的HA和FA酸碱性质的重要差异。与未改良土壤的HA和FA相比，LSM-HA和LSM-FA的酸性官能团含量较低，羧基和酚基类型基团的质子结合亲和力较大；羧基类型基团的异质性较小，对于HA来说酚基类型基团的异质性较小，对于FA来说酚基类型基团的异质性相似。用LSM改良导致土壤HA和FA的酸性官能团含量降低，羧基和酚基类型基团的质子结合亲和力略有增加。此外，施用LSM导致羧基类型基团的异质性降低，而似乎对LSM改良土壤HA和FA的酚基类型基团的异质性没有实质性影响。这些影响对HA比对FA更明显，并且随着LSM改良率的增加有轻微增加的趋势。
