Plaza César, Senesi Nicola, Polo Alfredo, Brunetti Gennaro
Centro de Ciencias Medioambientales, Consejo Superior de Investigaciones Cientificas, Serrano 115 dpdo., 28006 Madrid, Spain.
Environ Sci Technol. 2005 Sep 15;39(18):7141-6. doi: 10.1021/es050613h.
The soil acid-base buffering capacity and the biological availability, mobilization, and transport of macro- and micronutrients, toxic metal ions, and xenobiotic organic cations in soil are strongly influenced by the acid-base properties of humic substances, of which humic and fulvic acids are the major fractions. For these reasons, the proton binding behavior of the humic acid-like (HA) and fulvic acid-like (FA) fractions contained in a compost are believed to be instrumental in its successful performance in soil. In this work, the acid-base properties of the HAs and FAs isolated from a mixture of the sludge residue obtained from olive oil mill wastewater (OMW) evaporated in an open-air pond and tree cuttings (TC) at different stages of composting were investigated by a current potentiometric titration method and the nonideal competitive adsorption (NICA)-Donnan model. The NICA-Donnan model provided an excellent description of the acid-base titration data, and pointed out substantial differences in site density and proton-binding affinity between the HAs and FAs examined. With respect to FAs, HAs were characterized by a smaller content of carboxylic- and phenolic-type groups and their larger affinities for proton binding. Further, HAs featured a greater heterogeneity in carboxylic-type groups than FAs. The composting process increased the content and decreased the proton affinity of carboxylic- and phenolic-type groups of HAs and FAs, and increased the heterogeneity of phenolic-type groups of HAs. As a whole, these effects indicated that the composting process could produce HA and FA fractions with greater cation binding capacities. These results suggest that composting of organic materials improves their agronomic and environmental value by increasing their potential to retain and exchange macro- and micronutrients, and to reduce the bioavailability of organic and inorganic pollutants.
土壤酸碱缓冲能力以及大量和微量营养元素、有毒金属离子和土壤中异生物质有机阳离子的生物有效性、迁移和运输，受到腐殖物质酸碱性质的强烈影响，其中腐殖酸和富里酸是主要组分。基于这些原因，堆肥中所含的类腐殖酸（HA）和类富里酸（FA）组分的质子结合行为被认为对其在土壤中的成功应用至关重要。在这项工作中，通过电流电位滴定法和非理想竞争吸附（NICA）-唐南模型，研究了从露天池塘蒸发的橄榄油厂废水（OMW）污泥残渣与树木枝条（TC）混合物在不同堆肥阶段分离得到的HA和FA的酸碱性质。NICA-唐南模型对酸碱滴定数据进行了很好的描述，并指出了所研究的HA和FA在位点密度和质子结合亲和力方面的显著差异。相对于FA，HA的特点是羧酸型和酚型基团含量较低，但其质子结合亲和力较大。此外，HA的羧酸型基团比FA具有更大的异质性。堆肥过程增加了HA和FA中羧酸型和酚型基团的含量，降低了它们的质子亲和力，并增加了HA中酚型基团的异质性。总体而言，这些效应表明堆肥过程可以产生具有更大阳离子结合能力的HA和FA组分。这些结果表明，有机材料的堆肥通过提高其保留和交换大量和微量营养元素的潜力，以及降低有机和无机污染物的生物有效性，提高了它们的农艺和环境价值。
