Analysis of Diesel Fuel Contamination in Soils by Near-Infrared Reflectance Spectrometry and Solid Phase Microextraction-Gas Chromatography

A feasibility study was undertaken to determine whether the rapid, nondestructive analytical technology, near-infrared reflectance spectrometry (NIRS) could be used to predict total petroleum hydrocarbon (TPH) in contaminated soil. Hydrocarbon concentrations were determined on samples of diesel-contaminated soils by the solid phase microextraction-gas chromatography (SPME-GC) method. The same samples were then scanned for near-infrared reflectance spectrometry over the wavelength range 1100 to 2498 nm. Calibrations were developed between the NIR spectral data and the reference SPME-GC chemical data using stepwise multiple linear regression. Linear regression relationships between NIR-predicted TPH concentrations and reference data had r² of 0.68 and 0.72. These results indicate that the combination of NIRS and SPME-GC shows promise as a method for rapid estimation of TPH in soil. A major hurdle in the evaluation of methodology for hydrocarbons residues in soil is the challenge posed by the weathering of such residues.     

东北高寒地区麦田土壤活性有机质和环境因素关系的灰色分析

土壤圈是地球各圈层物质循环和能量交换的枢纽,在土壤圈中的养分变化和生物结构变化对农业持续发展的影响起重要作用［６］。土壤有机质层是动态的生态系统。它是由植物、动物和微生物及其它环境因素共同作用而组成的物质和能量交换系统。其中土壤中有机质释放的具有生物活性的酶类也参与这一过程。这种作用与有机质的合成和分解密切相关,其作用集中表现在活性有机质的动态变化方面。所以土壤活性有机质可以表征土壤物质循环特征,也可用以评价土壤质量的优劣。有机质的生产和矿化过程是土壤中生物因素和非生物因素共同作用的结果。因此,…     

缙云山森林土壤速效P的分布特征及其与物种多样性的关系研究

土壤状况直接影响着植物的生长发育 ,植物在整个生长发育过程中也能通过根系分泌物和枯落物等改善土壤的水、热、气、肥等理化性质[6 ] 。研究表明 ,土壤理化性质与种子萌发、幼苗定居密切相关 ,且幼苗在定居过程中能分泌氨基酸和有机酸作用于土壤 ,为其生长创造适宜的土壤条件[9] 。Ｍｃｋｅｅ研究指出 ,红树林的土壤理化性质影响着群落内植物种类的分布格局[10 ] 。Ｆｒａｎｃｏ ｖｉｚｃａｉｎｏ等对墨西哥加里佛尼亚沙漠的土壤性质和植物多样性的研究则表明 ,土壤的Ｃａ/Ｍｇ比例与植物多样性密切相关 ,且二者是协同发展的[11] 。可见 ,…     

东北黑土区坡耕地表层土壤颗粒有机碳和团聚体结合碳的空间分布

北黑土区典型漫岗坡耕地为研究对象,测定不同侵蚀程度地形部位表层土壤不同粒级有机碳、水稳性团聚体及其结合碳含量,探讨土壤侵蚀和沉积作用对表层土壤有机碳（SOC）损失、迁移和累积的影响.研究结果表明：与侵蚀微弱的坡顶相比,严重侵蚀的坡肩部位表层土壤水稳性大团聚体、矿质结合碳（IOC）和团聚体结合碳含量分别减少23﹪、17.5﹪和8.7﹪,而土壤颗粒有机碳（POC）含量无明显差异.长期处于沉积状态的坡脚部位,表层土壤大团聚体、POC和大团聚体结合碳含量分别较坡顶低56.1﹪、47.9﹪和67﹪;而IOC和微团聚体结合碳分别较坡顶高10﹪和18.7﹪.研究结果反映了土壤侵蚀以及耕作倾向于破坏水稳性大团聚体,其内部包裹的轻质、细颗粒物质易被地表水流迁移流失,加上下层土壤的稀释作用,导致侵蚀部位SOC减少.轻质活性碳组分在迁移和累积过程中易被微生物利用分解,沉积区土壤以IOC和微团聚体碳为主,形成一个惰性碳汇.     

内蒙古退化草原中与小叶锦鸡儿相关的小尺度土壤碳、氮资源异质性动态

小叶锦鸡儿在内蒙古典型草原中有着广泛分布,从而对小空间尺度土壤资源异质性产生强烈影响。退化草原中小叶锦鸡儿能够通过克隆生长形成灌丛斑块,不同大小斑块对应于其发育的不同阶段。因此,通过对与不同大小灌丛斑块相关的土壤有机碳（SOC）、全氮（STN）空间分布状况的分析,能够推断内蒙古退化草原中、与小叶锦鸡儿相关的小尺度SOC与STN异质性动态。结果表明：在内蒙古退化草原中,就0-5cm,5-10cm,10-20cm 3个土壤层次,小叶锦鸡儿均导致了与灌丛斑块相关小尺度上SOC与STN分布的空间异质性,且随着灌丛斑块的发育,这种异质性均不断增强,其中土壤表层0-5cm碳氮资源异质性的增强最为强烈,表现在灌丛斑块内部相对于外部（或边缘）对SOC与STN富集程度均显著增加。这表明内蒙古退化草原中,随着灌丛斑块自身的扩展,与小叶锦鸡儿相关小尺度上土壤碳氮资源空间异质性趋于增强。     

Influence of Temperature and Oil Content on the Soil/Air Partition Coefficient for Hexachlorobenzene in Oil-Contaminated Rice Paddy Field Soil

The soil/air partition coefficients (K _SA ) for hexachlorobenzene (HCB) in oil-contaminated (crude oil and diesel) rice paddy field soils were measured in a solid fugacity meter at different oil concentrations over the temperature range of 5 to 30°C at 100% relative humidity. The results showed that values of K _SA increased with a decrease of temperature. As for oil content, there is a critical separate phase concentration (CSPC) above which K _SA increased with increasing of oil content. When oil content is above CSPC, oil plays a role as a separate phase that enhances the sorption capacity of the soil. At a given temperature (20°C) values of CSPC depended on the natural organic matter (NOM) contents of the soil, while for a given oil concentration they depended on the temperature. The normalized oil/air partition coefficients ) for HCB deduced from K _SA for oils and experimentally determined with crude oil/quartz sand system were similar and 0.7–7 times higher than the normalized organic/air partition coefficient ), which implied that oil was a super sorbent. The enthalpies (ΔH_SA) for crude oil and diesel were 64.9 and 55.7 kJ mol^?1, respectively.     

汾河流域中下游植物群落物种多样性与土壤因子的关系

于2011年4~10月对汾河流域中下游33个样地128个样方的植被进行样地调查和土壤取样分析,并运用双向指示种分析（TWINSPAN）进行群落分类,用典范对应分析法（CCA）分析7种土壤因子与汾河流域中下游植物群落的分布关系,以揭示汾河流域中下游植被的物种多样性与土壤因子的关系。结果表明:（1）汾河流域中下游地区共发现植物121种,隶属33科81个属,其中以菊科、禾本科、藜科和蓼科植物最多,分别占总数的24.79%、14.05%、8.26%和7.43%,且芦苇的分布频率最高,达到49%。（2）双向指示种分析表明,汾河流域中下游33个样地分为8个群落类型（Ⅰ~Ⅷ）。（3）汾河流域中下游植物群落的Patrick丰富度指数和Shannon-Wiener指数变化趋势相似,而Simpson指数则与Patrick丰富度指数和Shannon-Wiener指数呈相反的变化趋势;Pielou均匀度指数的变化趋势与其他3个指数均不同。（4）汾河流域中下游土壤含水量、速效钾含量在不同群落类型的不同样地间的差异大部分达到显著水平,土壤养分具有比较明显的空间分布中度不均的特点。（5）汾河流域中下游地区的土壤有机质含量与物种Simpson指数以及土壤全氮与Pielou均匀度指数均具有显著负相关关系。（6）CCA排序结果表明,土壤含水量及速效磷、速效钾含量是影响植被群落分布最重要的环境因子。     

缙云山森林土壤速效K的分布特征及其与物种多样性的关系

土壤作为植物生长繁殖的基地 ,也作为一种重要的生态因子 ,总是与植物 (被 )协同发展的。Ｍｃｋ ｅｅ研究指出 ,红树林的土壤理化性质影响着群落内植物种类的分布格局[7] 。Ｆｒａｎｃｏ ｖｉｚｃａｉｎｏ等对墨西哥ＢａｊａＣａｌｉｆｏｒｎｉａ沙漠中的土壤性质和植物多样性的研究表明 ,土壤的Ｃａ/Ｍｇ比例与植物是协同发展的 ,土壤Ｃａ ,Ｍｇ含量及其比例与植物多样性存在一定的相关关系[8] 。可见 ,深入研究土壤理化性质与植物种类的分布、植物多样性的关系具有重要的理论和实践意义。最近 ,已有学者研究了速效Ｎ的空间格局及其与群落…     

油田区多环芳烃污染盐碱土壤活性微生物群落结构解析

多环芳烃(Polycyclic aromatic hydrocarbons,PAHs)是土壤中广泛存在的、美国环保总署(USEPA)优先控制的一类有毒(致癌、致突变)的持久性污染物,主要来源于人类活动。土壤微生物多样性是表征土壤质量变化的敏感指标之一。磷脂脂肪酸(PLFAs)分析方法是基于活性微生物细胞膜的PLFAs组分的生化检测技术,克服了传统培养方法只能分离出少量微生物(1%)的缺点。采用PLFAs方法,解析了土壤活性微生物对PAHs污染胁迫的反应。结果表明,土壤微生物分布情况可分为4种类型:Ⅰ型,微生物PLFAs种类最多,占该区土壤微生物PLFAs种类总数的57.7%,PAHs对变量的解释量最小;Ⅱ型,微生物PLFAs占PLFAs总数的30.8%,PAHs对变量的解释量较小;Ⅲ型,微生物PLFAs种类占总数的7.68%,PAHs对变量的解释量较大;Ⅳ型,微生物PLFAs的种类仅占总数的3.85%,PAHs对变量的解释量最大。相关性分析表明:土壤微生物PLFAs的种类、生物量和生态多样性指数与土壤中萘(Nap)、芴(Flu)、蒽(Ant)、苯并[K]荧蒽(Bkf)、苯并[a]芘(Bap)、茚并[1,2,3-cd]芘(Ind)的相对含量呈负相关关系;与苊(Ace)、菲(Phe)、荧蒽(Fla)、芘(Pyr)、苯并[a]蒽(Baa)的相对含量呈正相关关系;与PAHs的种类和浓度呈负相关关系。结果将为开展PAHs污染土壤的生态风险评价和微生物生物修复技术研究提供理论依据。     

石油污染盐碱土壤棉花根际微生物与石油烃降解关系

【目的】探讨棉花(Gossypium spp.)生长对石油烃(TPH)污染盐碱土壤微生物群落结构的影响,揭示根际微生物与TPH降解的相关关系。【方法】利用磷脂脂肪酸(PLFA)方法解析根际土壤活性微生物群落随棉花生长的动态变化特征。【结果】根际土壤先后出现了21种PLFAs,包括：饱和脂肪酸(SAT),标识除放线菌之外的细菌;甲基支链末端型饱和脂肪酸(TBSAT),标识除放线菌之外的革兰氏阳性(G+)细菌;标识真菌的多不饱和脂肪酸(PUFA);标识放线菌的甲基支链中间型饱和脂肪酸(MBSAT);标识革兰氏阴性(G?)细菌的单不饱和脂肪酸(MONO)和环丙基脂肪酸(CYCLO)。棉花根际与未栽种棉花的对照(CK)相比,根际土壤微生物PLFAs种类在苗期、蕾期、吐絮期分别增加了100%、83.3%、20.0%,生物量分别增加了53.9%、6.60倍和60.7%;土壤TPH降解率分别提高13.0%、28.0%和30.6%。相关性分析表明：根际土壤TPH降解与根际土壤微生物总生物量具有低度正相关关系(|r|=0.5),但与a14:0、a16:0、i15:0标记的G+细菌生物量高度正相关(|r|≥0.8)。【结论】棉花生长对石油污染盐碱土壤活性微生物群落结构具有显著(p<0.05)的影响,且加速了土壤TPH的降解。该结果将为今后更好地开展石油污染盐碱土壤的生物修复技术研究提供理论依据。     

血清硫氧还蛋白1与脑外伤患者的白质恢复的相关性分析

为探讨血清硫氧还蛋白1 (thioredoxin 1, Trx1)含量与脑外伤后白质恢复的相关性关系,本研究选取60例脑外伤患者,根据格拉斯哥昏迷指数(Glasgow coma scale, GCS)将患者分为3组(轻度,中度和重度脑外伤患者),每组20例,采用核磁共振成像(magnetic resonance imaging, MRI)检测各组患者头颅白质情况,并通过ELISA方法检测各组患者血清Trx1水平,最后利用SPSS软件Pearson方法检测血清硫氧还蛋白1含量与脑外伤后白质恢复的相关性。结果显示,轻度脑损伤患者的GCS分值明显高于中度和重度脑外伤患者;轻度脑外伤患者的Trx1含量明显高于中度和重度患者;轻度和中度脑外伤患者的白质恢复情况明显优于重度患者;脑损伤患者的血清Trx1含量和白质恢复程度呈正相关。本研究初步结论表明脑外伤患者的白质恢复情况与血清Trx1存在正相关性关系,这将为脑外伤的治疗提供新思路。     

Genetic dissection of the relationship between carbon metabolism and early growth in maize,with emphasis on key-enzyme loci

The determinism of carbon metabolism traits during early growth in maize has been investigated using a marker-based quantitative genetics approach. In addition to growth traits, concentration of carbohydrates and activity of four key enzymes of their metabolism (sucrose phosphate synthase, ADP-glucose pyrophosphorylase, invertases and sucrose synthase) have been measured in leaves of individuals of a recombinant inbred line population. Using more than 100 RFLP markers, quantitative trait loci (QTLs) were mapped for each biochemical and developmental trait. Causal relationships, suggested by previous physiological studies, were reinforced by common locations of QTLs for different traits. Thus, the strong correlation between growth rate and invertase activity, which may reflect sink organ strength, could be explained to a large extent by a single region of chromosome 8. Moreover, some of the structural genes of the enzymes mapped to regions with QTLs affecting the activity of the encoded enzyme and/or concentration of its product, and sometimes growth traits. These results emphasize the possible role of the polymorphism of key-enzyme genes in physiological processes, and hence in maize growth.     

溶磷细菌和丛枝菌根真菌接种对南方红豆杉生长及根际微生物和土壤酶活性的影响

以南方红豆杉实生苗为材料,采用盆栽实验探讨了高效溶磷细菌草木樨中华根瘤菌(Sinorhizobium meliloti)CHW10B与丛枝菌根真菌缩球囊霉(Glomus constrictum)单独和双接种条件下,其植株生长、根际土壤可培养微生物数量、土壤酶活和土壤微生物功能多样性变化,在微生态水平揭示接种对南方红豆杉生长的影响及其机制。结果表明:(1)各接种处理对南方红豆杉幼苗均有促生长作用,接种处理苗高、地径和生物量均较对照显著增加,并以双接种促进效果最好。(2)各接种处理提高了南方红豆杉根际土壤可培养细菌、真菌和放线菌含量,增加了土壤微生物碳源利用率,改变了土壤中物种的丰富度和均一度,增加了土壤中的生物多样性。(3)各接种处理促进了南方红豆杉根际重要土壤酶(酸性磷酸酶、脱氢酶、转化酶)活力的增加,且双接种的促进作用最为明显。可见,溶磷细菌(草木樨中华根瘤菌CHW10B)和丛枝菌根真菌(缩球囊霉)具有协同作用,两者同时接种可显著提高南方红豆杉根际土壤微生物数量及土壤酶活力,提高土壤微生物碳源利用率和土壤肥力,增加土壤中的生物多样性,从而达到间接促进宿主植物南方红豆杉生长的目的。     

Lipidomics of human Meibomian gland secretions: Chemistry, biophysics, and physiological role of Meibomian lipids

Human Meibomian gland secretions (MGS) are a complex mixture of diverse lipids that are produced by Meibomian glands that are located in the upper and the lower eyelids. During blinking, MGS are excreted onto the ocular surface, spread and mix with aqueous tears that are produced by lachrymal glands, and form an outermost part of an ocular structure called “the tear film” (TF). The main physiological role of TF is to protect delicate ocular structures (such as cornea and conjunctiva) from desiccating. Lipids that are produced by Meibomian glands are believed to “seal” the aqueous portion of TF by creating a hydrophobic barrier and, thus, retard evaporation of water from the ocular surface, which enhances the protective properties of TF. As lipids of MGS are interacting with underlying aqueous sublayer of TF, the chemical composition of MGS is critical for maintaining the overall stability of TF. There is a consensus that a small, but important part of Meibomian lipids, namely polar, or amphiphilic lipids, is of especial importance as it forms an intermediate layer between the aqueous layer of TF and its upper (and much thicker) lipid layer formed mostly of very nonpolar lipids, such as wax esters and cholesteryl esters. The purpose of this review is to summarize the current knowledge on the lipidomics of human MGS, including the discussions of the most effective modern analytical techniques, chemical composition of MGS, biophysical properties of Meibomian lipid films, and their relevance for the physiology of TF. Previously published results obtained in numerous laboratories, as well as novel data generated in the author’s laboratory, are discussed. It is concluded that despite a substantial progress in the area of Meibomian glands lipidomics, there are large areas of uncertainty that need to be addressed in future experiments.     

Effects of precipitation on photosynthesis and water potential in Andropogon gerardii and Schizachyrium scoparium in a southern mixed grass prairie

In grassland ecosystems, spatial and temporal variability in precipitation is a key driver of species distributions and population dynamics. We experimentally manipulated precipitation to understand the physiological basis for differences in responses of species to water availability in a southern mixed grass prairie. We focused on the performance of two dominant C₄ grasses, Andropogon gerardii Vitman and Schizachyrium scoparium (Michx.) Nash, in treatments that received ambient rainfall, half of ambient rainfall (“drought” treatment), or approximately double ambient rainfall (“irrigated” treatment). Water potentials of S. scoparium were lower than A. gerardii, suggesting superior ability to adjust to water deficit in S. scoparium. Additionally, drought reduced photosynthesis to a greater extent in A. gerardii compared to S. scoparium. Leaf-level photosynthesis rates were similar in ambient and irrigated treatments, but were significantly lower in the drought treatment. Although stomatal conductance was reduced by drought, this was not limiting for photosynthesis. Leaf δ¹³C values were decreased by drought, caused by an increase in C_i/C_a. Chlorophyll fluorescence measures indicated light-harvesting rates were highest in irrigated treatments, and were lower in ambient and drought treatments. Moreover, drought resulted in a greater proportion of absorbed photon energy being lost via thermal pathways. Reductions in photosynthesis came as a result of non-stomatal limitations in the C₄ cycle. Our results provide mechanistic support for the hypothesis that S. scoparium is more drought tolerant than A. gerardii.