【作者】 程书波；

【导师】 刘敏； 许世远；

【作者基本信息】 华东师范大学 ， 自然地理学， 2009， 博士

【摘要】 多环芳烃（PAHs）作为一种典型的持久性有机污染物（POPs）,在世界各种生态系统多介质中被广泛检出。土壤/沉积物作为PAHs的主要汇集和累积场所,而生长于土壤/沉积物上的各种生物是PAHs进入食物网累积,并发生迁移、转化的关键介质。因此,深入开展本项研究不仅对丰富PAHs生物地球化学研究内容具有重要的理论意义,而且可为提高生态和健康风险评价准确度和控制陆地生态系统PAHs污染提供重要科学依据。本研究选择典型土壤/沉积物—生物系统,通过实地资料收集与室内分析与模拟相结合的方法,联合环境地球化学、土壤学、与生物学等学科,研究了典型土壤/沉积物—生物系统中PAHs的累积、迁移与降解机制与影响因素。土壤—植物系统选择植物为优势生物的土壤—水稻系统为例,研究结果显示,上海市周边水稻田表层土壤（0-10cm）TPAHs含量水平空间差异很大。稻田表层土壤中5环和6环的高环PAHs占优势地位,约为43.4%,比例最小的化合物为2环和3环的低环PAHs,仅占总量的18.5%。表层土壤中PAHs总量、高、中、低环化合物和土壤理化性质之间均没有明显的相关关系。农田水稻植物体累积PAHs的途径主要为叶片吸附和吸收大气中的PAHs。稻根从土壤中获取PAHs也是水稻累积PAHs的一个重要途径。籽和茎主要依赖叶片与根部获取PAHs。TPAHs总量的根累积因子为0.05—0.08,PAH化合物根累积因子为0—0.41。说明上海农田水稻根系未发现从土壤中富集放大PAHs的现象。无论水稻种植前后,PAHs总量和化合物在土壤中的垂直分布都具有向下逐渐递减的趋势,而且自土壤表层向亚表层迅速减少,60cm以下变化较小,趋于稳定。水稻种植可以使土壤中PAHs含量明显降低。除萘外,菲和中、高环PAH化合物均在水稻种植后出现亚表层（10-20cm）截存富集现象。稻田土壤低环PAH化合物表现为随深度增加所占比例逐渐增大的规律,而中、高环PAH化合物则显示出相反的趋势。SOC（土壤有机碳）是影响土壤PAHs累积与迁移的关键因素,而BC（碳黑）重要性远小于SOC。相对富集系数计算结果显示,水稻种植前PAHs在土壤剖面中出现了隔层相对富集的现象,水稻种植后PAHs在土壤剖面中的相对富集系数与种植前有很大差异,表明水稻种植能够有效去除土壤剖面中PAHs,影响PAHs垂直变化。另外,水稻种植前后土壤剖面PAHs相对富集系数与1g k_OW相关性均不明显,表明PAHs自身理化性质对其迁移特征影响较弱,其他作用机制（如淋溶、扰动等）影响较强。沉积物—动物系统选择动物为优势生物的冬季潮滩沉积物—底栖动物系统为例,研究结果表明,长江口滨岸边滩表层沉积物中TPAHs总量为87.7—1851.0ng g^-1,平均值为599.7 ng g^-1,具有从长江口内向口外逐渐减少的趋势。边滩表层沉积物中环和高环PAH化合物占优势地位。崇明表层沉积物TPAHs含量表现为中潮滩＞高潮滩＞低潮滩的特征,且低环化合物占绝对优势,与边滩表层沉积物形成鲜明对比,高环化合物所占比例自高潮滩向低潮滩逐渐减少。表层沉积物理化性质中SOC是控制PAHs累积与迁移最重要的影响因素。来源辨析结果表明边滩表层沉积物PAHs主要来源于不完全燃烧,崇明低潮滩显示出较强的石油类产品泄漏来源的特征。长江口潮滩底栖动物中BLG弹涂鱼TPAHs含量最高,达到891.0 ng g^-1,CM中潮滩蟹体内TPAHs含量最低,为36.1 ng g^-1,表现出营养级放大效应。所有底栖动物体内累积的低环PAH化合物占有绝对统治地位,且所有动物体内均未检测到4环PAH化合物,仅在部分样品中有少量高环PAH化合物检出。脂含量是影响PAHs在底栖动物体内累积的关键因素。长江口滨岸潮滩动物体PAHs的含量水平与BSAF并没有随沉积物PAHs含量、SOC的变化而对应变化的趋势。TPAHs和PAH（5+6）的BSAF均较小,表明底栖动物自沉积物中富集高环PAH化合物的能力较弱。由于水溶性较强,沉积物中低环PAH化合物被底栖动物食用后易于吸收,而且底栖动物还可以从上覆水体直接获取低环PAH化合物,所以PAH（2+3）化合物的BSAF要高许多。BSAF与LogK_OW具有较强的相关性,当LogK_OW＜6时,BSAF值通常随着K_OW值的升高而升高,当LogK_OW＞6时,BSAF值则开始降低。土壤—微生物系统选择受PAHs污染严重且微生物为优势生物的Mosel河流沿岸土壤—微生物系统为例,研究结果发现,Temmels土壤添加的D₁₀-PA被很快释放,并被本土微生物迅速降解,在2周时间内降解了约92%,并在4周内降解了约99%,以后基本保持稳定。加入Konzerbr（u|¨）ck土壤中的D₁₀-PA同样很快被释放并被本土微生物降解,但D₁₀-PA的降解速度约为Temmels降解速度的一半,这与两种土壤溶液的D₁₀-PA降解速度正好吻合,后者土壤中微生物数量约为前者的一半强,表明微生物数量对于PAHs降解速度具有重要作用。Temmels土壤微生物降解组和灭菌对照组结果表明,Temmels土壤中的PAHs能够被本土微生物少量降解。Konzerbr（u|¨）ck土壤微生物降解组PAHs则未发生明显降解现象。Temmels土壤的Saar煤炭对照组降解了20.0±2.7 mg kg^-1,约占初始浓度的19.0%,表明Temmels土壤的Saar煤炭对照组PAHs被微生物小幅降解,显示加入额外Saar煤炭后土壤中PAHs可降解能力会提高。Konzerbr（u|¨）ck土壤的Saar煤炭对照组中TPAHs共降解了46.0±1.1 mg kg^-1,约占初始浓度的31.5%,表明Konzerbr（u|¨）ck土壤的Saar煤炭对照组中PAHs可以被本土微生物明显降解,这与Konzerbr（u|¨）ck土壤的微生物降解组几乎无降解形成鲜明对比,表明本土微生物能够大幅度降解新鲜Saar煤炭。Novgorod煤炭的加入没有明显增加Temmels土壤PAHs的降解水平。Konzerbr（u|¨）ck土壤的Novgorod煤炭对照组TPAHs共降解了初始浓度的20.4%。结果显示Novgorod煤炭的加入,大幅提高了PAHs的降解水平,但与Konzerbr（u|¨）ck土壤的Saar煤炭对照组对比,降解百分比低于后者,表明本土微生物降解外来煤炭的能力小于本地煤炭。Temmels土壤Saar煤炭对照组中PAH化合物降解量对总降解量贡献率排序为PAH（2+3）＞PAH（5+6）＞PAH（4）,其中Nap、1-MNap和PA降解最明显;Konzerbr（u|¨）ck土壤的Saar煤炭和Novgorod煤炭对照组中PAH化合物降解量对总降解量贡献率大小顺序一致,均为PAH（2+3）＞PAH（4）＞PAH（5+6）,其中中Saar煤炭对照组Nap、1-MNap、2-MNap和PA降解最明显。Novgorod煤炭对照组中Nap、1-MNap和PA降解最明显。更多还原

【Abstract】 Polycyclic aromatic hydrocarbons（PAHs）,as a set of typical persistent organic pollutants,have been found in worldwide multimedia and are of great concern. Soil/sediment is an important sink of PAHs and organisms living in the soil/sediment are key media for PAHs transferring and accumulating through the food web. Therefore,conducting the present study has important theoretical significance for enriching PAHs biogeochemical researches.Moreover,the results will also improve the accuracy of ecological and health risk assessments and means of controlling PAHs pollution.The present study selected typical soil/sediment-organism systems.Then,the mechanisms of PAHs accumulation,transfer and biodegradation and its effecting factors were elucidated combining field survey and laboratory simulation methods and environmental geochemistry,agrology and biology subjects.Soil-rice system which the organisms living in is predominated by rice was selected as typical soil-plant system.The results showed that TPAHs levels in surface soils varied significantly in different sampling sites around Shanghai.All surface soils were prevalent of PAH（5+6）as about 43.4%of TPAHs while PAH（2+3）as the least compounds were only about 18.5%.TPAHs and individual PAH compounds levels had no significant correlation with soil physicochemical characteristics.In agriculture field,rice plant accumulated PAHs mainly through absorption and adsorption airborne PAHs by leaves.Another important organ for rice getting PAHs was root which can accumulate PAHs from soil.Stem and seed received PAHs depending on transfer from leaf and root.TPAHs and PAH compounds root accumulate factor were 0.05-0.08 and 0-0.41,respectively,which indicated that there was no biomagnification of PAHs by rice root through around soil.In both soil profiles before and after rice planting,TPAH and PAH compounds levels were gradually decreased with soil depth.The decrease was most significant between surface soil and sub-surface soil and pollution levels were getting steady in soils below 60 cm.There was obvious declination of PAHs levels in soil after rice planting.PA and PAH（4）were caught and enriched in sub-surface layer（10-20 cm） except of Nap after rice planting.PAH（2+3）levels decreased with soil depth,however, PAH（4）and PAH（5+6）showed opposite trends.SOC（soil organic carbon）was the most important factor affected PAHs transferring and accumulating.In contrast,BC （black carbon）was no significant relationship with PAHs soil mobility.Relative enrichment factor results suggested that PAHs occurred relative enrichment every other layer in soil profile before rice planting.However,the relative enrichment factors changed greatly after rice planting,which showed that rice planting was able to remove PAHs from soil profile and change the vertical variation of PAHs levels. Additionally,relative enrichment factors had no significant correlation with 1g K_OW in both soil profiles,indicating that PAHs behaviors in soil profile were not influenced by their physicochemical characteristics but other factors（such as eluviate and organism disturbing）.Sediment-benthic animal system in winter from the Yangtze estuarine tidal flat was chosen as typical sediment-animal system because that benthic animals were majority in the system.The results suggested that TPAHs levels in surface sediment from the Yangtze estuarine tidal flat were from 87.7-1851.0 ng g^-1,averaged in 599.7 ng g^-1and decreased from inner to outer of the Yangtze river mouth.PAHs in surface sediments were dominated by PAH（4）and PAH（5+6）.However,TPAHs levels in surface sediments from the Chongming island characterized by middle tidal flat＞high tidal flat＞low tidal flat.PAH（2+3）was the major PAH compounds.The relative content of PAH（5+6）decreased gradually from high tidal flat to low tidal flat.Source identification results showed that PAHs in surface sediments along the Yangtze estuary mainly came from incomplete combustion while PAHs in surface sediments from the Chongming island were mostly petrogenic PAHs.Tidal flat fish （periophthelmus cantonensis）from BLG site had the highest TPAHs level about 891.0 ng g^-1while crab（Sesarma）from Chongming middle tidal flat had the lowest level about 36.1 ng g^-1,which indicated that high trophic level animal tended to magnify PAHs concentration through food web.Crabs accumulated similar amount of PAHs, which was in relation to their hunting behavior and living habits.PAH（2+3）were the majority while PAH（4）was not found in all benthic animals’ bodies.Lipid content may strongly control PAHs accumulation in benthic animals’ bodies.PAHs levels and BSAF（bio-sediment accumulation factor）didn’t vary according to PAHs levels and SOC in surface sediments.BSAFs of TPAHs and PAH（5+6）were lower which suggested benthic animals only had weak ability accumulating them from surface sediments.However,due to their higher water solubility,PAH（2+3） tended to be caught more by benthic animals,which caused higher BSAFs.In addition, BSAF had strongly correlation with LogK_OWWhen LogK_OW＜6,BSAFs increased according to LogK_OWwhile they decreased when LogK_OW＞6.Soil-microorganisms system in two sites along Mosel river was chosen as typical soil-microorganisms system because the soil was highly polluted by PAHs and microorganisms were the majority of organisms.Results showed that D₁₀-PA added to Temmels soil was biodegraded quickly about 92%and 99%during 2 and 4 weeks, respectively.Similarly,D₁₀-PA added to Konzerbr（u|¨）ck soil was biodegraded a large amount during 4 weeks,but the speed is only half of Temmels soil,which was in consistent with microorganism amount in two soil slurries.Bioavailable and killed control sets results for Temmels soil were compared and slight biodegradation was found.However,there was no significant biodegradation happened in Konzerbr（u|¨）ck soil.TPAHs had been biodegraded about 20.0±2.7 mg kg^-1in Saar coal control of Temmels soil.That is,19.0%of initial TPAHs in Saar coal control of Temmels soil was biodegraded,which indicated that PAHs of fresh Saar coal could be biodegraded by native microorganisms in Temmels soil.For Konzerbr（u|¨）ck soil,there was 46.0±1.1 mg kg^-1PAHs biodegraded in its Saar coal control.That is,31.5%of initial TPAHs in Saar coal control of Konzerbr（u|¨）ck soil,which was greatly contrary to its bioavailable set.This showed that extra Saar coal also could improve PAHs bioavailability in Konzerbr（u|¨）ck soil.However,extra Novgorod coal didn’t increase PAHs biodegradation in Temmels soil.For Konzerbr（u|¨）ck soil,extra Novgorod coal led to 20.4%of initial TPAHs level.Compared to its Saar coal control,Novgorod coal control for Konzerbr（u|¨）ck soil biodegraded less PAHs,showing native microorganisms were not used to immigrant coals but native coals. For Temmels soil,the order of contribution to total biodegradation of PAH compounds in Saar coal control was PAH（2+3）＞PAH（5+6）＞PAH（4）.Nap,1-MNap and PA had been biodegraded more in comparison of other PAHs.The order of contribution in Saar coal control and Novgorod coal control of Konzerbr（u|¨）ck soil had the same trend:PAH（2+3）＞PAH（4）＞PAH（5+6）.Nap,1-MNap,2-MNap and PA were easiest to be biodegraded in Saar coal control while Nap,1-MNap and PA were biodegraded strongest in Novgorod coal control.更多还原