几种多环芳烃在不同类型稻田土壤中的降解行为

    Degradation of Polycyclic Aromatic Hydrocarbons in Paddy Soils From Different Regions in China

    • 摘要: 为揭示我国不同类型稻田土壤中多环芳烃(PAHs)的降解率,采集了8个地区的稻田土壤,分别加入菲、荧蒽和苯并a蒽进行室内培养试验,分析不同类型稻田土壤中PAHs降解速率的差异及其与土壤理化性质的关系。结果表明,不同类型稻田土壤中PAHs降解能力由大到小依次为四川石灰性紫色土、黑龙江黑土、重庆中性紫色土、山西褐土、北京潮土、安徽黄褐土、河南潮土和湖南黄壤。不同类型稻田土壤中PAHs降解率在培养7 d时均可达51.5%,28 d后降解率大于80%。土壤中PAHs易降解程度由高到低依次为菲、荧蒽和苯并a蒽。除四川石灰性紫色土和重庆中性紫色土外,PAHs能显著增加其他类型土壤中总细菌数量和菲降解过程中的双加氧酶功能基因phnAc数量。冗余分析结果表明,土壤中菲和荧蒽降解速率与土壤中NH4+-N和有机质含量呈显著正相关(P < 0.05),与pH值和含水量呈负相关。土壤中苯并a蒽降解速率与土壤理化性质均无显著相关性(P>0.05)。不同类型稻田土壤中PAHs自然降解速率和留存时间有所差异,可通过在土壤中添加氮肥等营养物质促进PAHs的降解。

       

      Abstract: Polycyclic aromatic hydrocarbons (PAHs) belong to an important class of persistent organic contaminants ubiquitously found in soils. Their fate in soil varies depending on both soil properties and their chemical structure. It is therefore important to understand the factors that control PAHs biodegradation in different soil environments. A study was conducted on eight paddy soils which are geographically distributed in different region of China. Time-course laboratory incubation was employed coupled with GC-MS analysis to explore the effects of variable soil properties on PAHs degradation, and evaluate the correlation between them. It was found that the capacities of PAHs degradation of different paddy soils were as follows:Sichuan (calcareous purple soil) > Heilongjiang (black soil) > Chongqing (neutral purple soil) > Shanxi (cinnamon soil) > Beijing (fluvo-aquic soil) > Anhui(yellow-cinnamon soil) > Henan (fluvo-aquic soil) > Hunan (yellow earth). The degradability of three PAHs was as follow:phenanthrene > fluoranthene> benzoa anthracene. Real-time quantitative polymerase chain reaction (qPCR) of 16S rRNA genes and phenanthrene dioxygenase functional gene phnAc demonstrate that the abundance of bacteria and phnAc gene was significantly stimulated by the addition of PAHs in these soil except the soils from Sichuan and Chongqing. Redundancy analysis indicate that the degradation pattern of phenanthrene and fluoranthene was positively associated with the content of NH4+-N and soil organic matter significantly (P < 0.05), and negatively correlated with soil pH and water content. The degradation of benzoa anthracene was not significantly correlated with all the environmental parameters in this study (P> 0.05). Overall, results show that the fate of PAHs varies in different paddy soils, and the application of nitrogen and organic fertilizers could potentially stimulate the PAHs degradation rate in soils. The results of the study could provide basic information for evaluating the mechanism of PAHs degradation in natural soils and developing remediation strategy in China paddy soils.

       

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