鸡粪堆肥有机物演化对重金属生物有效性影响研究

采用离子色谱、三维荧光光谱、紫外-可见吸收光谱和多元统计分析,研究了鸡粪堆肥水溶性有机物(DOM)和重金属组成与演化特性,探究了有机物演化对重金属生物有效性的影响及其机理.结果显示,堆肥升温期和高温期有机物降解最为剧烈,产生了大量苹果酸、酒石酸、乙酸和草酸,其浓度分别在2097.55~2155.61、39.24~51.58、12.52~12.90及1.68~2.31 mg·L-1之间;堆肥降温期和二次发酵过程,蛋白类物质降解,腐殖质类物质合成,DOM的腐殖化率和缩合度增大,稳定性增强.堆肥过程中水溶态重金属中Fe的浓度(1.069~7.106 mg·L-1)最高,Al、As、Cr、Cu和Mn的浓度(0.1~1.008mg·L-1)其次,Pb的浓度(0.003~0.02 mg·L-1)最低,随着堆肥的进行水溶态重金属含量呈下降趋势(Al除外),相关性分析显示,水溶态重金属主要结合在腐殖质类物质上,生物可利用性低.分析结果表明,堆肥可通过降低水溶态重金属的含量和将水溶态重金属络合在腐殖质类物质上降低产品中重金属的生物有效性.

Influence of Organic Matter Evolution During Composting on the Bioavailability of Heavy Metals

Ion chromatography, fluorescence spectroscopy, UV-visible absorption spectroscopy and multivariate statistical analysis were applied to study the composition and evolution characteristics of dissolved organic matter (DOM) and heavy metal extracted from chicken manure during composting, and the influence of organic matter evolution on the bioavailability of these heavy metals was further investigated. The result showed that, a large number of organic acids were generated during the active stage, and their concentrations were in the range of 2097.55-2155.61 mg·L^-1, 39.24-51.58 mg·L^-1, 12.52-12.90 mg·L^-1 and 1.68-2.31 mg·L^-1, respectively. During the curing stage, protein-like matter was degraded, whereas humic-like substances were formed, which increased the humification degree, condensation degree and stability of DOM. The content (1.069-7.106 mg·L^-1) of dissolved iron ranked first during composting, that of dissolved Al, As, Cr, Cu and Mn (0.1-1.008 mg·L^-1) ranked second, and the concentration of dissolved lead was the lowest. Concentrations of all heavy metals decreased during composting except aluminum. Furthermore, the result from correlation analysis showed that these dissolved heavy metals were bound with DOM, and their bioavailability was low. It could be concluded that, the bioavailability of the heavy metals in chicken manures became lower through the decrease of dissolved heavy metals and the binding between dissolved heavy metals and humic-like substances.