【作者】 黄勇；

【导师】 项文化；

【作者基本信息】 中南林业科技大学 ， 生态学， 2011， 博士

【摘要】 多环芳烃(Polycyclic Aromatic Hydrocarbon,简称PAHs)是含有两个及两个以上苯环的持久性亲脂有机污染物,它生物累积性强,存在于环境介质中,对人类健康构成潜在的威胁,引起了各国科学家的极大重视。城市森林是城市生态系统的重要组成部分,一方面植物叶片对环境中PAHs具有一定的吞噬能力,另一方面土壤微生物和酶活性受地上植物的影响,能降解土壤中的PAHs。因此,城市森林建设在改善环境发挥重要作用。但目前缺乏定量分析和研究城市森林冠层叶片与地下土壤的PAHs行为及变化规律。研究PAHs大气中的传输途径、各植物的吸收差异和土壤降解能力,为城市绿化植物选择和合理配置提供科学依据。利用气质联用仪对樟树(Cinnamomum camphora)、桂花(Opsmanthus fragrans)、广玉兰(Magnolia grandiflora)、红檵木(Redrlowered loropetalum)4种绿化植物叶片的PAHs含量进行测定,分析其节律变化、叶片结构与富集之间的关系。同时研究不同PAHs浓度下土壤微生物和酶的变化。主要研究结果为：1、四种植物叶片中PAHs含量特征樟树、桂花、广玉兰和红繼木4种植物叶片中的PAHs总含量的差异性显著(p<0.05),分别为7.58mg·kg-1、4.34mg·kg-1、3.66 mg·kg-1、11.13mg·kg-1。其中樟树、桂花和红檵木3种植物叶片中菲(PHE)的含量最高,其次为荧蒽(FLA),第三为芘(PYR)；广玉兰叶片中浓度较高的前三位PAHs分别为菲(PHE)、荧蒽(FLA)和萘(NAP)。4种植物叶片中,2-4环的中低环芳烃均占PAHs总含量的90%以上,而5～6环的高环芳烃小于10%,6环的仅占4%以下。2、叶片中PAHs含量节律变化规律4种植物叶片中PAHs,总含量表现出显著的季节性差异(P<0.05)。4月和7月,樟树叶片中PAHs,总平均含量最高,1月和10月红檵木叶片中PAHs总平均含量最高,广玉兰叶片中PAHs总的平均含量最低。其中1月份樟树、桂花和广玉兰叶片中PAHs总含量日变化规律基本一致,最大值出现在下午14点,最小值出现在晚上20点。红檵木叶片中的PAHs总含量最小值出现上午8点,最大值出现在下午14点。4月份樟树、桂花和红檵木叶片中的PAHs总含量最大值出现在下午15点,但樟树叶片中PAHs总含量在上午9点和次日凌晨3点较低,而桂花和红檵木叶片中PAHs总含量均在晚上21点达到最低。广玉兰4月份的PAHs总含量变化不大。7月份4种植物各时间段叶片中PAHs总含量变化趋势基本一致,呈显著的单峰曲线,最大值出现在晚上20点,最小值出现在下午14点。10月份樟树、桂花和广玉兰叶片中PAHs总含量日变化规律基本一致,最大值出现在晚上20点,最小值出现在下午14点。红檵木叶片中PAHs,总含量日变化规律与其它3种植物相反,最大值出现在14点,最小值出现在晚上20点。3、叶片结构特征与富集PAHs能力的关系4种植物叶片解剖结构与富集PAHs能力的相关关系均达到显著(P<0.05)。其中栅栏组织厚度、海绵组织厚度和叶片总厚度均与PAHs含量呈负相关,叶片栅栏组织、海绵组织和叶片总厚度越小,气态和颗粒态PAHs吸附量越多,对气态和颗粒态PAHs的富集作用较强。而种间其他叶片结构与PAHs含量间相关关系不显著(P>0.05),可能是因为生理特性的差异,表现为某些结构上的差异对PAHs的吸附不敏感,如有的角质层可能较难穿透、不同植物间气孔能力不一致、不同树种叶片气孔对PAHs粒径的选择不一致等。4、PAHs对土壤微生物的影响樟树、桂花、广玉兰和红檵木4种绿化植物和土壤不同PAHs水平0 g·kg-1(CK),2 g·kg-1(L1),10 g-kg-1(L2)和50 g.kg-1(L3)模拟结果表明,栽植樟树、广玉兰和红檵木3中植物幼苗的土壤中,受PAHS处理后细菌、真菌、放线菌和微生物总数都低于对照,栽植桂花幼苗的土壤中,PAHs处理后细菌和微生物总数高于对照。栽植桂花和红檵木幼苗的土壤中,PAHs处理后真菌数量高于对照。放线菌数量都表现为L1>CK>L2>L3。5、PAHs对土壤酶的影响广玉兰、桂花、红檵木3种绿化植物土壤中过氧化氢酶活性年均值均表现为3种污染处理高于对照。只有樟树L3处理与对照过氧化氢酶活性年均值基本相等,L1和L2则低于对照。4种绿化植物土壤中磷酸酶活性年均值表现为高于对照。广玉兰和桂花3种PAHs污染浓度的土壤中多酚氧化酶活性年均值低于对照。樟树表现为L1>CK>L2>L3,红檵木则表现为L2>L1>CK>L3。更多还原

【Abstract】 Polycyclic aromatic hydrocarbons (PAHs), composed of two or more fused aromatic rings, are ubiquitous, bioaccumulative and persistent pollutants. With rapid population growth, concurrent urban expansion and industrial development, contamination of PAHs in the environment has been a serious public health problem that greatly affects human beings health, and ecosystems functions. Urban forests as an important component of urban ecosystems, it plant leaves could absorb pollutants such as PAHs from the air, and plant also could affect soil prepertis including microbial community and enzymes that metabolize PAHs. Hence, urban forests play an critical role in improving the environment and achieve harmonious development of man and nature.In this study, four widely used for urban green plant species(Cinnamomum camphor a,Opsmanthus fragrans, Magnolia grandiflora and Redrlowered loropetalum) were chosen to determine PAHs content in leaves and investigated the effects on PAHs on soil microbes and enzymes activities. The results could provide scientific basis for plant species selection and arrangement. Mian results showed as follows:1. Charactersistics of PAHs content in four plant species leavesPAHs contents in leaf differed significantly with plant species (p<0.05) and were 7.58mg·kg-1,4.34 mg·kg-1,3.66 mg·kg-1 and 11.13mg·kg-1 for C. camphora, O. fragrans, M. grandiflora and R. loropetalum, respectively. PHE content in leaves was the highest of PAHs for C. camphora, O. fragrans and R. loropetalum, and FLA and PYR was the second and the third one. Howerver, for leaf of M. grandiflora, the individual categories of PAHs contents in leaf were ranked in order as PHE> FLA> NAP. The 2-4 ring PAHs were the main components of the 16 PAHs and accounted for more than 90%, the 5-6 ring PAHs comprised a small percentage of total PAHs and was lower than 10%.2. Seasonal and daily changes in PAHs contents in four plant species leavesPAHs contents in four plant leaves showed significant differences among four seasons (P<0.05). The highest PAHs contents in leaves of C. camphora occurred in April and July, while that of R. loropetalum occured in January and October. In January, diurnal variations of PAHs contents in C. camphora, O. fragrans, M. grandiflora were similar, with the highest content appeared in 14 p.m. and the lowest content appeared in 20 p.m.. But the PAHs content in R. loropetalum was highest in 14 p.m and was lowest in 8 a.m. In April, the PAHs content in C. camphora, O. fragrans, R. loropetalum was highest in 15 p.m, but the PAHs content in C. camphora was smaller from 9 am to 3 am the following day, and that in O. fragrans, R. loropetalum were the lowest at 9 pm. The PAHs contents in M. grandiflora changed little in April. In July, PAHs contents of leaves in four plants showed a similar change pattern that was the single curve, the highest PAHs contents appeared at 20 pm and the smallest contents appeared at 14 pm.3. Relationship of leave structures with PAHs contentsThere were closely relationships between leaf anatomical structures and PAHs contents for plant species. Palisade tissue thickness, spongy tissue thickness and the total leaf thickness were negatively correlated with PAHs contents. The thinner were the palisade tissue thickness, spongy tissue thickness and the total leaf thickness, the more did the aired and particle PAHs enrich. Other targets of leave structures showed no significant difference with PAHs contents (p>0.05), such as stratum corneum was hard to be penetrated and stomata in different trees would selected to scavenge the different particle sizes of PAHs.4. Effect of PAHs on soil microbial communityUsing pot experiment in greenhouse, the soils planted with C. camphora, O. fragrans, M. grandiflora and R. loropetalum seedlings were treated without diesel oil addition (control) and at three diesel contents (2g·kg-1, L1; 10 g·kg-1, L2 and 50g·kg-1, L3) to stimulate different levels of PAHs pollution. Soil microbes were investigated for one year. The numbers of bacteria, fungi, actinomyces and total microbes in PAHs polluted soils of C. camphora, M. grandiflora and R. loropetalum were lower than that in control soils. The numbers of bacteria, total microbes in PAHs polluted soils of O. fragrans were higher than that in control soils. The number of fungi in polluted soils of O. fragrans and R. loropetalum were higher than that in control soils. The numbers of actinomyces followed the order of L1>CK>L2>L3.5. Effects of PAHs on soil enzymesCatalase activities in polluted soils of M. grandiflora, O. fragrans and R. loropetalum were stronger than those in control soils. Catalase activities of C. camphora were in order of L3=CK>L1>L2. Phosphatase activities in polluted soils of four tree species were stronger than those in control soils. Polyphenol oxidase activities in polluted soils of M. grandiflora, O. fragrans were weaker than those in control soils, and the order of C. camphor a was ranked as L1>CK>L2>L3, and that of R. loropetalum was followed the order of L2>L1>CK>L3.更多还原