芘降解菌在石油污染土壤修复过程中的代谢调控

沈抚灌区是我国面积最大、污灌历史最长的石油类污水灌溉区，土壤中大分子量多环芳烃污染严重，对当地粮食生产与生态安全造成严重危害。对此类污染土壤进行生物修复，对保证农产品的安全，实现当地人与自然的可持续发展具有重大的意义。 本研究以沈抚灌区污染土壤中大分子多环芳烃芘为主要研究对象，采用稳定同位素比率分析技术（IRMS），以磷脂脂肪酸（PLFA）为生物标记物，分析污染土壤参与芘降解的优势微生物类群；并以此为指导，采用分子生物学手段和传统微生物学分析方法，筛选土壤中的高效降解菌，并追踪其释放到土壤中后的动态变化与调控。 从沈抚灌区土壤富集培养芘的降解菌，经过双层平板法初筛和芘降解菌液体摇瓶复筛，获得5株以芘为唯一碳源生长的具有较高降解活性菌株。 将筛选的降解菌投加到污染土壤中，以13C标记的芘为代谢底物，以土壤微生物的磷脂脂肪酸为生物标记物，采用稳定同位素比率分析方法(GC-C-IRMs)，分析投加的降解菌在原位土壤中的降解作用。结果显示，与不加菌的对照土壤相比，富含13C的磷脂脂肪酸指纹图谱相似度较高的为投加了菌株B05和菌株B15的土壤，芘的降解效率也最高，表明这两株菌在原位土壤芘降解中发挥了重要作用。根据形态学观察、16项生理生化鉴定和16S rDNA序列分析结果，将菌株B05鉴定为 Aminobacter ciceronei，将菌株B15鉴定为 Microbacterium arabinogalactanolyticum。菌株B05初步确定为一株新的芘降解菌，并对菌株培养条件进行了优化。 采用PCR-DGGE方法，研究了筛选的5株降解菌在不同的营养条件下释放到土壤中后的数量和代谢活性的变化。PCR-DGGE图谱分析表明：投加初期外加菌在竞争中占据优势，但是随时间推移，营养物质的消耗，优势逐渐消失，PCR-DGGE的条带趋向于一致。菌株B05的稳定期相对较长，在DGGE图谱中的条带相对密度大，而且对芘的降解率最高，是一株具有潜在应用价值的高效降解菌。混合菌比单一菌降解率高，添加碳氮源有利于外加菌群更快更好的适应在污染土壤中生存，而且有助于对多环芳烃的降解。

典型污染海湾河口沉积物中砷的形态分布研究

锦州湾是我国较大的浅水海湾之一，该湾西南五里河沿岸汇集数家工厂排污直接人海， 形成该湾口处的最大污染源。其西南部潮滩地段已成为我国海域污染最严重的区域之一。 本文对葫芦岛3条河流、五里河口和锦州湾水体、沉积物中As的含量、分布、形态及行为进行了系统研究。结果表明，葫芦岛的连山河和五里河未受到明显的As污染，沉积物总As含量一般低于10 mg•kg-1，河水As含量一般低于10 μg•L-1，茨山河下游紧邻葫芦岛锌厂，受到了严重的As污染，沉积物As含量达75.2 mg•kg-1。五里河口区As污染非常严重，锌厂在该区排污口处沉积物As含量高达3176.1 mg•kg-1，超过国家沉积物As标准158倍。受锌厂排污的影响锦州湾As污染也很严重，沉积物中As最高含量达到569.5 mg•kg-1。沉积物和孔隙水As含量在剖面上具有相似的变化趋势，表明孔隙水As含量主要受沉积物As含量影响。锦州湾沉积物中As主要以可交换态存在，残渣态次之，盐酸提取态最少，表明锦州湾沉积物中As的活性很强，有大量的可交换态As随时会进入上覆水体，是重要的As释放源，沉积物中大量As的释放可能会对葫芦岛和锦州湾地区生态系统造成严重的威胁。 以盐度和酸碱度作为环境影响因子进行的释放模拟实验，结果显示：不同盐度条件下，沉积物中的As均在48h左右达到最大释放量。此时，盐度为0‰的水体中As的释放量最大，而其他两种盐度的水体中As的释放量较小且二者相差不大。另外，在室温条件下，随着pH值的升高，沉积物中As的释放量逐渐增加。 通过对不同形态的单一含砷矿物的As提取效果研究得出：对于分级提取方法中吸附态砷的最佳提取条件应为1M KH2PO4 (pH5) 24h, 无定型铁氧化物上结合的砷0.2M oxalic/oxalate (pH3)避光 6h, 硫化亚铁上结合的砷，0.2M oxalic/oxalate (pH3)避光 1h。

石油污染土壤的物理化学处理-生物修复工艺与技术研究

由于污染条件不同，造成石油污染土壤的污染程度、污染性质差异很大，单纯依靠一种方法或技术难以进行清洁和修复，并使其恢复土壤的自然属性，因此，必须采用物理、化学、生物及工程方法进行综合治理.该项工作基于国内外同类研究基础，根据土壤中石油类污染物的含量和性质，提出了石油污染土壤物理化学净化—生物修复的基本思想，采取了有针对性的分级、分段处理方法，研究和开发了高效低耗、经济易行的处理技术，并建立了相应的示范工程，为该技术的应用和推广奠定了基础.

用植物油淋洗修复多环芳烃污染土壤

研究用植物油淋洗修复多环芳烃污染土壤的效果、植物油淋洗剂再生与回用的可行性、植物油的生态效应。采用了批处理法和土柱法对多环芳烃污染土壤进行修复，结果表明：油土比1：1的条件下，批处理法可以去除土壤中90％以上的多环芳烃，多环芳烃的质量转移过程可以用经验模型模拟。恰当的运行条件下，土柱法可去除土壤中90％以上的多环芳烃，但是根据土壤中多环芳烃浓度的高低，植物油的用量是批处理法的2～4倍。无论是批处理法，还是土柱法，土壤水分含量都影响了植物油去除土壤中多环芳烃的能力。采用了化学氧化法、溶剂提取法和吸收剂吸收法对植物油进行再生，结果表明：臭氧和双氧水能氧化植物油中的多环芳烃，但不理想，紫外线及双氧水在pH＝3的条件下可氧化植物油中76.5％的多环芳烃。按植物油／乙醇1:3的比例对植物油进行6级处理可氧化植物油中87％的多环芳烃。活性炭二级处理可去除植物油中87％的多环芳烃，实现植物油的再生。高等植物生长实验说明土壤中的植物油对燕麦及萝卜的生长起了抑制作用，土壤呼吸实验证明，残留在土壤中的植物油可被生物降解，但是必须保证良好的氧气及营养供应。用植物油修复多环芳烃污染土壤具有可行性。

超积累植物筛选及污染土壤植物修复过程研究

超积累植物是植物提取修复的核心，同时也是污染环境修复领域研究的热点与前沿。针对目前已发现的超积累植物数量与对重金属提取种类较少的现状，并根据修复实践的需求，本研究确立了以超积累植物的筛选为主要研究内容并就一些强化措施进行了初步探索，同时根据已报道的植物修复研究的阶段性成果，对污染土壤植物修复的基本概念、原理、方式、强化机制等相关的修复过程进行了系统总结，结果如下：（1）超积累植物应同时具有四个基本特征，即临界含量特征、转移特征、耐性特征和富集系数特征。（2）龙葵和球果掉菜是Cd超积累植物，在Cd投加浓度为259／kg条件下，其茎和叶中Cd含量分别为103.80mg／kg和124.57mg／kg及107.7Omg/kg和150.10mg／kg。植物体内积累的Cd主要分布在茎和叶中。这2种植物不具有同时超积累Pb、Cu或Zn的能力。（3）施加鸡粪后植物对Cd的提取率提高了35.7％～97.0％；采用开花期收获超积累植物的复种方式，植物提取率可以提高到1.43倍和1.75倍。（4）以杂草为筛选对象，将成为筛选超积累植物的一个突破口。（5）盆栽筛选试验具有可操作性强、易于实施等优点，是筛选超积累植物值得尝试的一种方法。（6）现发现的超积累植物几乎均来源于污染区，本研究表明，未污染区也可能存在超积累植物。（7）栽培措施对植物修复效果有较大影响，与现代农业高新技术相结合是植物修复技术成功应用于修复实践的一条捷径。

多氯联苯污染土壤的生态修复研究

本研究针对我国土壤PCBs的污染特点，初步探讨了含有PCBs的变压器油分析与测定，两种典型的机合修复过程和PCBs代谢产物的植物毒理三个方面的问题，得出如下结论：1．采用一种经过检验的新前处理方法，分析变压器油样中含有2种二氯联苯，4种三氯联苯，4种4氯联苯，3种5氯联苯，1种六氯联苯，共13种PCBs同类物，各同类物在ΣPCB中占的百分含量在1.2％-13.4％之间。2．采用KMnO4和好氧降解菌系拙合时，祸合方式不同，藕合效果不同，土壤介质不同锅合的效果也存在差异。3．模拟缺氧条件下，不含脱氯微生物啤酒厂污泥，在经过一定迟滞期后（4星期），存在脱氯情况，添加按计卜油醇可减少迟滞期，有明显的诱导作用。单独投加零价金属的脱氯效果与其化学性质和投加量有关，Fe。和zno辛禺合厌氧微生物的脱氯效果要好于两者单独的脱氯效果，其中Zn0耦合厌氧微生物的脱氯效果最好。4，在实验区间内，两种白菜的POD可与根伸长、发芽率一起作为CBA的生态毒理指标，且比根伸长和发芽率敏感，SOD和CAT则不适合。

石油烃污染土壤植物-微生物联合修复及机理研究

运用土壤学、微生物学、生态学和统计学方法，系统地开展了石油污染土壤的植物-微生物联合修复研究，对植物-微生物修复的生态影响进行了分析，并从根际微生物区系变化与根分泌物特性两个角度深入探讨了污染土壤植物一微生物联合修复的机理。室内模拟、室外盆栽、田间微区实验的结果表明：（1）植物-微生物联合修复对不同浓度石油烃污染土壤有较好的修复效果，125d的修复周期中对土壤中石油污染物的降解率为7.1％-69.8％，随污染物浓度的升高，联合修复对土壤中污染物的降解作川增强；（2）植物一微生物联合修复作用可能会长期持续，并对难降解物质PAHs存在修复潜力；（3）在本实验条件下，采用经济作物与降解微生物联合修复会降低土壤有机质含量，对土壤生态系统的结构和功能不会产生严重的干扰，对土壤生态环境的影响可以在短时间恢复；（4）植物一微生物联合作用方式在于植物与微生物的相互作用，作用区为植物根际，微生物在植物根际区域的种类数量和生化特征存在差异；植物分泌物对于微生物具有调节作用，促使污染物的生物降解。并以本试验研究为例，进一步探讨石油污染土壤植物一微生物联合修复的机理，利石油污染土壤的植物一微生物联合修复的影响因子进行调控研究，联合修复的主要影响因子是营养因子，其次是污染物浓度。石油污染土壤的植物一微生物联合修复研究，对土壤微生物群落，植物根际效应及潜在自然生物降解获得了进一步的理解，为污染土壤修复技术提供了科学依据和理论支持。

稠油污染土壤生物修复的微生物筛选及工艺调控

稠油组分非常复杂，胶质沥青质含量较高，使稠油污染土壤的生物修复难度很大。对稠油中胶质沥青质分的降解是彻底修复稠油污染土壤的关键。试验中利用辽河油田污染土壤中筛选并纯化出来的几株细菌、真菌和放线菌，以胶质沥青质作为碳源，考察不同菌株处理的去除率变化。发现0d-14d期间是微生物去除胶质沥青质的活跃期，42d之后土壤中胶质沥青质的减少趋缓，是生物修复的转折点。筛选出优势降解菌株：细菌22B；真菌中F2006、F2008、F9902，放线菌A2013、A2016混合菌F2006+22B、F6＋22B。同时考查了表面活性剂吐温-80对菌株去除胶质沥青质能力的影响，发现吐温-80对不同菌株有促进或抑制作用。利用上述优势菌株处理5ryn稠油污染土壤，并在42d时，通过采取补加菌液、添加N、P营养物质和添加碳源处理来提高微生物对土壤中稠油的去除能力。经过56天的处理，细菌22B对稠油的去除率最高，达27．420＆；混合菌的去除率在23.64％-26.24％。比较三种处理措施对微生物降解稠油能力的影响时，发现不同菌株对这三种措施的反应并不相同。同时土壤中残留石油烃的族分析证实了土壤中的重质成分是可以被微生物降解的；而稠油污染土壤中的烷烃和芳香烃的含量则呈现动态变化。稠油污染土壤的生物修复后的毒性检验表明，不同菌株处理土壤的毒性因选择的菌株及采取的措施不同而异，其中土壤毒性最小的是22B添加碳源处理；毒性最强的是F2008加菌处理。补加菌液、添加营养和碳源措施会使微生物对稠油降解能力有所加强，但是也加速了某些微生物产生毒性较稠油更大的中间产物的生成，使土壤更加不适合植物的生长。本研究从辽河油田污染土壤中筛选出石油烃降解菌株，对稠油中最难降解的胶质沥青质进行处理，从中选择优势的降解菌株对稠油污染土壤进行生物修复，为稠油污染土壤的生物修复打下理论基础。

青杨组(Populus Section Tacamahaca Spach)不同种对非生物胁迫的响应差异

土壤是人类赖以生存的自然环境和农业生产的重要资源，目前土壤受到干旱和盐胁迫的危害越来越严重。杨树具有适应性强、生长快和丰产等特性，本论文以青杨组杨树为模式植物，研究杨树对土壤干旱和盐胁迫的生态生理及蛋白质组学反应，研究成果可为我国干旱半干旱地区营造人工林、防止沙漠化提供理论依据，也为恢复与重建盐污染地区退化生态系统提供科学指导。主要研究结果如下： 1 青杨不同种对逐步干旱胁迫的响应差异 将来自喜马拉雅山东缘高海拔的康定杨和低海拔的青杨枝条扦插在温室中，用来检测它们对逐步干旱胁迫的响应。研究结果表明来自不同海拔的杨树对逐步干旱胁迫的适应性反应是不一样的。株高、叶片发育、叶片相对含水量、丙二醛、过氧化氢等指标的显著性变化在青杨中比在康定杨中来得早些，而且随着干旱胁迫程度的增加，这些参数的变化越来越明显，尤其是当青杨受到严重干旱胁迫的时候；而可溶性蛋白、可溶性糖、游离脯氨酸、抗氧化酶活力变化在康定杨中来得早一些。与青杨相比，在干旱胁迫下，康定杨仍能保持较好的植株生长和叶片发育；康定杨也能在逐步干旱条件下积累更多的可溶性蛋白、可溶性糖、游离脯氨酸及抗氧化酶活力，但是在丙二醛和过氧化氢含量方面增加的更少些。而且，我们的研究结果表明高海拔的康定杨有更强的耐干旱能力，杨树对干旱胁迫的适应能力与干旱发生的速度、强度、持续时间及两种杨树的海拔有关。 2 干旱胁迫下青杨不同种的蛋白质组学分析 来自青杨和康定杨雌株的枝条扦插在温室中，用来研究它们对干旱胁迫的蛋白质组学反应。采用TCA-丙酮/酚提取法提取总蛋白，并进行双向电泳分析。在每个处理的重复图像中都能检测到1,000 个以上的蛋白点。在青杨中有58 个蛋白在干旱处理后发生显著变化，其中22 个蛋白通过肽指纹图谱成功鉴定。康定杨中有69 个蛋白的表达量发生了显著变化，其中有25 个蛋白通过肽指纹图谱成功鉴定。这些被鉴定的蛋白主要参与了光合作用、氧化还原平衡、信号传导、能量代谢、蛋白质合成等过程。尽管被鉴定的蛋白只占叶片总蛋白的很少一部分，但这些被鉴定的干旱响应蛋白可能对维持植株内部平衡方面有重要作用。 3 青杨的盐胁迫响应 青杨植株分别用 0、50 和100 mM NaCl 溶液进行处理。叶片相对含水量、叶绿素a、b 含量、CO2 同化速率和气孔导度的降低表明叶绿体受到了盐胁迫的影响。过氧化氢、丙二醛含量及电导率的升高表明细胞受到了伤害。可溶性糖、游离脯氨酸含量及抗氧化酶含量的上升增加了植株耐盐胁迫的能力。在每个处理的重复图像中都能检测到1,000 个以上的蛋白点。其中有38 个盐响应蛋白被成功鉴定，有16 个蛋白(点4、10、11、14、15、21、24、26、27、28、33、34、35、36、37 和38)出现在盐胁迫的植株中；3 个蛋白(点10、11 和35)只出现在重度盐胁迫处理中；而1 个蛋白(点1)只出现在对照处理中。2 个蛋白(点1 和2)表达量下降，其余蛋白点表达量都增加。被鉴定的蛋白一部分参与了生理生化反应，而另一部分则在信号传导、蛋白质合成等方面有重要作用。盐胁迫下的生理生化变化及蛋白质组学的联合研究有利于青杨对盐胁迫的适应性分析。 Soil is the indispensable environment for human survival and important resource for agriculture development. Nowadays soil is threatened by drought stress and salt stress. Poplars (Populus spp.) possess some characters such as strong acclimilation, fast growth and great production of biomass. In this study, different species of Populus section Tacamahaca spach were used as model plants to investigate the ecophysiological and proteomic responses to drought stress and salt stress. Our results can provide theoretical evidence for the afforestation and prevention of desertification in the arid and semi-arid areas, and also can supply scientific direction for the reconstruction and rehalibitation of ecosystems contaminated by salinity. The results are as follows: 1 Adaptive responses to progressive drought stress in two contrasting poplar species originating from different altitudes Cuttings of Populus kangdingensis C. Wang et Tung and Populus cathayana Rehd., originating from high and low altitudes in the eastern Himalaya, respectively, were examined during one growing season in a greenhouse to determine the effects of progressive drought stress. The results manifested that the adaptive responses to progressive drought stress were different in these two species from different altitudes. Significant changes in height increment, leaf development, relative water content (RWC), malondialdehyde (MDA) and hydrogen peroxide (H2O2) appeared earlier in P. cathayana than in P. kangdingensis, whereas changes in soluble protein, soluble sugar, free proline and antioxidant enzymes appeared earlier in P. kangdingensis. In addition, changes in these parameters became more and more significant when the drought stress progressed, especially under severe drought stress in P. cathayana. Compared with P. cathayana, P. kangdingensis was able to maintain a superior height increase and leaf development under drought stress. Also, P. kangdingensis possessed greater increments in soluble protein, soluble sugar, free proline and antioxidant enzymes, but lower increments in MDA and H2O2 than did P. cathayana when the cuttings were exposed to progressive drought stress. Our results suggest that P. kangdingensis originating from the high altitude has a better drought tolerance than does P. cathayana originating from the low altitude. Furthermore, this study manifested that acclimation to drought stress are related the rapidity, severity, duration of the drought event and the altitude of two contrasting species. 2 Proteomic responses to drought stress in two contrasting poplar species originating from different altitudes The cuttings from a female clone of P. kangdingensis and P. cathayana were used to determine proteomic response to drought stress, respectively. Total proteins of the leaves were extracted by a combination of TCA-acetone and phenol, and separated by two-dimensional gel electrophoresis. More than 1,000 protein spots were reproducibly detected on each gel. 58 differentially expressed spots were detected under drought stress in P. cathayana and 22 drought-responsive proteins were identified by peptide mass fingerprint. 69 differentially expressed spots were detected under drought stress in P. kangdingensiss and 25 drought-responsive proteins were identified by peptide mass fingerprint. The identified proteins are involved in several processes, i.e., signal transduction, protein processing, redox homeostasis, CO2 fixation and energy metabolism. Although the proteins identified in this investigation represent only a very small part of the poplar leaf proteins, some of the novel drought-responsive proteins identified here may be involved in the establishment of homeostasis in response to drought stress in the woody plants. 3 Responses to salt stress in P. cathayana Cuttings from a female clone of P. cathayana were treated by Hoagland’s solution: 0, 50, 100 mM NaCl, respectively. Salinity significantly decreased the relative water content of leaves, the contents of chlorophyll a and chlorophyll b, CO2 assimilation rate (A) and stomatal conductance (gs) in both salt stress treatments，which suggested the chloroplast was affected by salt stress. The observed increases of H2O2 and malondialdehyde contents and electrolyte leakage suggested that salinity caused cellular damage, whereas the increases in compatible solutes and in the activities of antioxidant enzymes enhanced the salt tolerance. More than 1,000 protein spots were reproducibly detected on each gel, and 38 salt-responsive proteins were successfully identified by peptide mass fingerprint (PMF). 16 spots (spot 4, 10, 11, 14, 15, 21, 24, 26, 27, 28, 33, 34, 35, 36, 37 and 38) absent in the control sample were induced by the salt treatment, and three spots (spot 10，11 and 35) were present only in the severely salt-stressed treatment. The %vol of the differentially expressed proteins generally increased with progressing salt stress, except for the decreased %vol of two proteins (spot 1 and 2) under salt stress and the presence of spot 1 only in the control sample. Some of the novel salt-responsive proteins identified here may be involved in physiological, biochemical response to salt stress in P. cathayana, the other identified proteins play a role in numerous cellular functions, including signal transduction and protein processing. An integrated physiological, biochemical and proteomic approach was used here to systematically investigate salt acclimation in poplar.

Cross-correlation between WMAP and 2MASS: non-Gaussianity induced by the SZ effect

We study the non-Gaussianity induced by the Sunyaev-Zel'dovich (SZ) effect in cosmic microwave background (CMB) fluctuation maps. If a CMB map is contaminated by the SZ effect of galaxies or galaxy clusters, the CMB maps should have similar non-Gaussian features to the galaxy and cluster fields. Using the WMAP data and 2MASS galaxy catalogue, we show that the non-Gaussianity of the 2MASS galaxies is imprinted on WMAP maps. The signature of non-Gaussianity can be seen with the fourth-order cross-correlation between the wavelet variables of the WMAP maps and 2MASS clusters. The intensity of the fourth-order non-Gaussian features is found to be consistent with the contamination of the SZ effect of 2MASS galaxies. We also show that this non-Gaussianity can not be seen by the high-order autocorrelation of the WMAP. This is because the SZ signals in the autocorrelations of the WMAP data generally are weaker than the WMAP-2MASS cross-correlations by a factor f(2), which is the ratio between the powers of the SZ-effect map and the CMB fluctuations on the scale considered. Therefore, the ratio of high-order autocorrelations of CMB maps to cross-correlations of the CMB maps and galaxy field would be effective to constrain the powers of the SZ effect on various scales.

Remediation of Persistent Organic Pollutants (POPs) in Two Different Soils

Persistent organic pollutants (POPs) are a set of chemicals that are toxic, persist in the environment for long periods of time, and biomagnify as they move up through the food chain. The most widely used method of POP destruction is incineration, which is expensive and could result in undesirable by-products. An alternative bioremediation technology, which is cheaper and environ-mentally friendly, was tested during this experiment. Two different soil types containing high and low organic matter (OM) were spiked with 100 mg/kg each of pyrene and Aroclor 1248 and planted with three different species of grasses. The objective of the study was to determine residue recovery levels (availability) and potential effectiveness of these plant species for the remediation of POPs. The results showed that recovery levels were highly dependent on the soil organic matter content—very low in all treatments with the high OM content soil compared to recoveries in the low OM soil. This indicates that availability, and, hence, biodegradability of the contaminants is dependent on the organic matter content of the soil. Moreover, the degree of availability was also significantly different for the two classes of chemicals. The polyaromatic hydrocarbon (PAH) recovery (availability) was extremely low in the high organic matter content soil compared to that of the polychlorinated biphenyls (PCBs). In both soil types, all of the plant species treatments showed significantly greater PCB biodegradation compared to the unplanted controls. Planting did not have any significant effect on the transformation of the PAHs in both soil types; however, planting with switchgrass was the best remedial option for both soil types contaminated with PCB.

石油污染土壤的生物修复技术

The soil contaminated by petroleum hydrocarbons and main methods of cleaning the pollutants were dealt with in the paper.The key principles,technological types, effect factors ,consolidation of the technology,present situation and development of the bioremediation of the soil contaminated by petroleum hydrocarbons were presented.

污染土壤中多环芳烃的共代谢降解过程

The biodegradation of most PAHs with high molecular weight is carried out by means of cometabolism. The development of the theory about cometabolic degradation is reviewed in this paper, and the achievements on the cometabolic degradations of PAHs are also summarized. It is demonstrated that glucose, biphenyl, organic acids and mineral oil could be used as cometabolic substrate to enhance the degradation rate of PAHs, and there are complex interactions in the microbiological degradation process among different PAHs. Some low molecular PAHs could serve as cometabolic substrate, which could also be used to enhance the transformation rate of high molecular weight recalcitrant PAHs. To achieve the cometabolic degradation of the PAHs in the soils, the following problems must be solved: the screening out of efficient degradative strains, the selection of the appropriate cometabolic substrate, the addition of surfactant if necessary and the optimization of operational parameters with the contaminated soils. These problems are the important parts of the project for the cometabolic degradation of PAHs in the soils.

Spatial distribution of soil heavy metal pollution estimated by different interpolation methods: Accuracy and uncertainty analysis

Mapping the spatial distribution of contaminants in soils is the basis of pollution evaluation and risk control. Interpolation methods are extensively applied in the mapping processes to estimate the heavy metal concentrations at unsampled sites. The performances of interpolation methods (inverse distance weighting, local polynomial, ordinary kriging and radial basis functions) were assessed and compared using the root mean square error for cross validation. The results indicated that all interpolation methods provided a high prediction accuracy of the mean concentration of soil heavy metals. However, the classic method based on percentages of polluted samples, gave a pollution area 23.54-41.92% larger than that estimated by interpolation methods. The difference in contaminated area estimation among the four methods reached 6.14%. According to the interpolation results, the spatial uncertainty of polluted areas was mainly located in three types of region: (a) the local maxima concentration region surrounded by low concentration (clean) sites, (b) the local minima concentration region surrounded with highly polluted samples; and (c) the boundaries of the contaminated areas. (C) 2010 Elsevier Ltd. All rights reserved.

Evaluation of a sequential extraction for the speciation of thorium in soils from Baotou area, Inner Mongolia

Sequential extraction procedures were widely applied for speciation of radioactive elements. In this study, the sequential extraction procedure developed by Martinez-Aguirre was employed for quantification of different chemical forms of thorium in the soil. The total amount of thorium in contaminated soil was much higher by four-fold than the local background value. The soil properties affect the amount of thoriurn and distribution of fractions in contaminated soil. Results showed that the proportion of thorium in soils from Baotou was found as the residual fraction (F5 + F6) > absorbed fraction (F3), coprecipitated fraction (F4) > carbonates fraction (172) and exchangeable fraction (F1) that could be available to plants. The recovery, calculated by ratio of the sum of the six fractions to the pseudo-total content of thorium, was in the range from 96% to 110%. A comparison was carried out between the sequential extraction and the single extraction to evaluate the selectivity of the extractants. It was found that the amount of thorium of absorbed fraction (H) was higher in the single extraction than that estimated in the sequential extraction, possibly duo to transform of the labile form. While for non-residual fraction analysis, the single extraction scheme was a desirable alternative to the sequential extraction procedure.