The steroids of hexactinellid sponges

The Hexactinellida ('glass sponges') are commonly considered to be the most basic metazoans. Steroids of 20 species from different taxa were studied for chemotaxonomy and biosynthetic implications. All Hexactinellida contain cholest-5-en-3#-ol (cholesterol) and/or its saturated derivative 5!(H)-cholestan-3#-ol, along with their C-24-alkylated homologues. Where 5!(H)-stanols are present, they regularly co-occur with their 3-keto analogues. The steroid concentrations generally decrease with increasing carbon numbers, similar to sterol distributions typically found in marine sediments. These features argue against de novo sterol biosynthesis operating in hexactinellid sponges. Rather, we suggest a dietary uptake of (⁵-stenols and their stereoselective transformation via 3-keto intermediates to 5!(H)-stanols.     

Chemo-ecological studies on hexactinellid sponges from the Southern Ocean

Hexactinellids (glass sponges) are an understudied class with syncytial organization and poor procariotic associations, thought to lack defensive secondary metabolites. Poriferans, though, are outstanding sources of bioactive compounds; nonetheless, a growing suspicion suggests that many of these chemicals could be symbiont-derived. In Polar latitudes, sponges are readily invaded by diatoms, which could provide natural products. Hexactinellids are typical of deep waters; but in Antarctica, they dominate the upper shelf providing shelter and food supply to many opportunistic mesograzers and macroinvertebrates, which exert strong ecological pressures on them. Aiming to examine the incidence of defensive activities of hexactinellids against consumption, feeding experiments were conducted using their lipophilic fractions. Antarctic hexactinellid and demosponge extracts were tested against the asteroid Odontaster validus and the amphipod Cheirimedon femoratus as putative sympatric, omnivorous consumers. Hexactinellids yielded greater unpalatable activities towards the amphipod, while no apparent allocation of lipophilic defenses was noted. After chemical analyses on the lipophilic fractions from these Antarctic glass sponges, quite similar profiles were revealed, and no peculiar secondary metabolites, comparable to those characterizing other poriferans, were found. Instead, the lipidic compounds 5α(H)-cholestan-3-one and two glycoceramides were isolated for their particular outspread presence in our samples. The isolated compounds were further assessed in asteroid feeding assays, and their occurrence was evaluated for chemotaxonomical purposes in all the Antarctic samples as well as in glass sponges from other latitudes by NMR and MS. Characteristic sphingolipids are proposed as chemical markers in Hexactinellida, with possible contributions to the classification of this unsettled class.     

微藻脂肪酸在中国近海缺氧海水-沉积物界面中的降解模拟研究

通过一系列培养实验,模拟了有机物在中国近海季节性缺氧环境沉积物-海水界面的降解过程.以中国近海典型的赤潮藻中肋骨条藻(Skeletonema costatum)为研究对象,对中肋骨条藻中的几种典型脂类生物标志物在不同程度缺氧海水-沉积物界面中的降解行为进行追踪.通过分析测定不同培养时间获取的不同含氧体系(氧饱和度100%、50%,25%和0%)中中肋骨条藻4种主要脂肪酸[14:0、16:0、16:1(7)、20:5]的含量,结果表明,在前2~3周4种脂肪酸迅速减少,之后则变化很慢甚至几乎不变.在不同含氧体系中4种脂肪酸的降解存在很大差异,14:0、16:1(7)、20:5经过两个月的培养,在4种不同含氧体系中几乎降解完全,而16:0在4种体系中剩余25%~35%.根据multi-G模型对4种脂肪酸降解进行定量描述,结果表明,每种化合物可以分为降解较快和较慢的部分,各化合物的平均降解速率常数k av范围在0.079~0.84 d-1,14:0与16:1(7)的降解在25%含氧体系中最快,在降解最快的体系中,14:0的k av是最慢体系(含氧50%)的2.3倍,16:1(7)的k av是最慢体系(含氧100%)的1.7倍;16:0的最快降解速率出现在无氧体系中(0.17 d-1),是最慢体系[50%含氧体系(0.079 d-1)]的2.1倍;20:5的降解速率常数则与含氧量呈正相关.结果表明,影响中国近海缺氧海区沉积物-海水界面中中肋骨条藻中脂肪酸降解的因素除了含氧量之外,有机化合物本身的结构和性质以及环境中微生物作用等对其降解也存在着很大影响.     

山东半岛南部近海表层沉积物中脂类生物标志物的组成及形态分析

分析了山东半岛南部近海表层沉积物中游离态和碱不稳定结合态脂类物质的组成,结果显示:脂肪酸呈现以16∶0为主峰的单峰形分布趋势,具明显偶碳优势,海源为其主要来源,脂肪酸主要以结合态形式存在,不同类别的脂肪酸形态分布略有差异,脂肪酸的结构和来源是影响脂肪酸形态分布的重要因素;同样以海源为主的甾醇则主要以游离态形式存在,但陆源甾醇的结合态比重相对较高;烷烃呈现以C29烷烃为主峰的单峰形分布趋势,陆源输入是其主要来源;烷烃主要以游离态形式存在,且UCM(不可分辨成分)峰仅出现在游离态烷烃的气相色谱图中。     

牵牛花对石油污染盐碱土壤微生物群落与石油烃降解的影响

利用磷脂脂肪酸（PLFAs）生物标记法分析野生型牵牛花（Pharbitis nil （Linn.） Choisy）根际土壤微生物群落结构,探讨牵牛花生长对石油烃污染土壤微生物群落与石油烃降解的影响.结果表明,供试土壤微生物群落中,先后出现了24种PLFAs,包括标记细菌的饱和脂肪酸（SAT）、革兰氏阳性菌（G⁺）的末端支链饱和脂肪酸（TBSAT）、革兰氏阴性菌（G^-）的单不饱和脂肪酸（MONO）和环丙脂肪酸（CYCLO）、真菌的多不饱和脂肪酸（PUFA）和放线菌的中间型支链饱和脂肪酸（MBSAT）等六大类型.PLFAs的主成分分析（PCA）表明,牵牛花根际与对照组（未种牵牛花,CK）土壤微生物群落具有明显的差异,微生物多样性在春季增加83%、夏季增加140%、秋季增加50%;微生物的生物量在春季增加97.6%,夏季增加116.3%,秋季增加60.3%.牵牛花根际与对照组相比土壤中石油烃降解率明显提高,在春、夏、秋季分别提高了7.5%、34.2%和19.7%;并且,在牵牛花生长的不同季节石油烃的降解率有明显的差异,春季为22.3%,夏季为51.8%,秋季为38.0%.相关性分析表明,石油烃降解与土壤微生物总生物量具有中等程度的相关性（|r|=0.75）;与G⁺细菌、甲烷氧化菌的生物量具有高度相关性,相关系数|r|>0.8;与G^-的生物量具有中度相关性,相关系数为|r|=0.74;与真菌的生物量具有低度相关性,相关系数为|r|=0.36,与放线菌没有相关性,相关系数为|r|<0.30.     

金佛山不同高程岩溶泉初春时期溶解态脂类生物标志物研究

为探究金佛山不同高程的表层岩溶泉入春时期溶解有机质的来源和转化特点,于2017年1、2和4月分别在水房泉(2045 m)和碧潭泉(730 m)进行采样,利用气相色谱-质谱联用仪(GC-MS)对样品中脂类生物标志物(溶解态正构烷烃、脂肪酸)的组分进行定量分析.结果表明,水房泉和碧潭泉溶解态正构烷烃(T-ALK)含量变化范围分别为1546~19314 ng·L~(-1)和1089~12234 ng·L~(-1),平均含量分别为8036、5553ng·L~(-1);脂肪酸变化范围分别为4163~13048 ng·L~(-1)和5519~10079 ng·L~(-1),平均含量分别为8039和8421 ng·L~(-1).由于春季气温回升和降水增多,正构烷烃和脂肪酸含量总体均处于上升趋势.同时,基于正构烷烃分子参数CPI、OEP、TAR、L/H发现,溶解态正构烷烃以细菌源为主,高等植物源输入逐月升高,以低海拔处的碧潭泉变化更为显著.溶解态脂肪酸1、2月以细菌源为主,4月以真菌源和高等植物源脂肪酸为主,细菌源比重依然较高,且因不同海拔的生境不同导致碧潭泉的水生生物输入较水房泉更稳定.     

广州秋季灰霾污染过程大气颗粒物有机酸的污染特征

收集广州秋季一个灰霾过程大气颗粒物昼夜样品,进行了26种脂肪酸和8种二元羧酸的定量分析(GC/MS).结果表明,大气脂肪酸和二元羧酸的污染水平较高.灰霾与非灰霾期间脂肪酸和二元羧酸浓度之比分别为1.9和2.5.污染上升过程脂肪酸和二元羧酸晚上浓度(653 ng.m-3)高于白天浓度(487 ng.m-3),而在污染降低过程,白天脂肪酸和二元羧酸浓度(412 ng.m-3)要高于晚上浓度(336 ng.m-3).采样期间二元羧酸和脂肪酸日均值浓度总体上与颗粒物和碳质组分的变化趋势一致.脂肪酸和二元羧酸与有机碳比值大体上与颗粒物污染成反比,比值随着大气颗粒物的增加而降低,27号晚上之后,随着颗粒物的降低而开始增加,说明有机酸主要以直接排放为主,而灰霾对有机酸的富集有明显抑制作用.基于特征比值法(C3/C4)及相关性分析,表明秋季灰霾污染过程脂肪酸和二元羧酸都是以一次排放为主.     

美人蕉根系对铜绿微囊藻的化感作用

通过在铜绿微囊藻(Microcystis aeruginosa)培养物中添加美人蕉(Canna indica)种植水的方式,研究了美人蕉种植水对铜绿微囊藻的抑制效应. 结果表明:①以蒸馏水培养3 d收集获得的美人蕉种植水对铜绿微囊藻的生长有明显的抑制作用; 在与铜绿微囊藻共培养20 d后,美人蕉种植水对铜绿微囊藻的抑制率最高可达64.4%,对照组铜绿微囊藻中ρ(Chla)是种植水的1.98倍. ②美人蕉种植水(根系分泌物)中有乳酸、己二酸、棕榈酸、乙二醇和硬脂酸等10种脂肪酸,其根系提取物中有乳酸、3-儿茶酚乳酸、亚油酸和棕榈酸等19种物质. ③美人蕉种植水和根系提取物中乳酸含量均最高,美人蕉根系提取物中化合物种类多于种植水,美人蕉种植水中绝大部分化合物在其根系提取物中均可找到. 推断美人蕉自身代谢产生的化感物质释放于水体中,可有效抑制铜绿微囊藻的正常生长.      

Comparative study of microbial community structure in di erent filter media of constructed wetland

Comparisons of microbial community structure, in eight filter media of zeolites, anthracite, shale, vermiculite, ceramic filter media, gravel, steel slag and bio-ceramic, were undertaken by analyzing the phospholipid fatty acid (PLFA) composition. A total of 20 fatty acids in the range of C11 to C20 were determined but only 13 PLFAs were detected in steel slag. They consist of saturated fatty acids, branched fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids. The variation of fatty acids was revealed in the relative proportions of these fatty acids in di erent media. The aerobic prokaryotes were the predominant group in all media. The PLFA composition showed significant di erences among the eight di erent media by Tukey’s honestly test. It was found that steel slag was significantly di erent in the microbial community as compared to other filter media, probably due to its alkaline e uent. Steel slag alone is probably not a good choice of substratum in constructed wetlands. The principle components analysis (PCA) showed that zeolites, bio-ceramic, shale and vermiculite had a similar microbial community structure while steel slag and ceramic filter media were distinct from other media.     

北京PM2.5中有机酸的污染特征及来源

采用GC/MS定量分析了2003年9月至2004年7月期间北京市PM2.5中33种脂肪酸(C10～C32)和10种二元酸(diC2～diC11)的含量.研究表明,脂肪酸具有明显的偶数碳优势,4个季节中最丰富的脂肪酸物种都是棕榈酸和硬脂酸(C16、C18).脂肪酸总浓度年均值为493.89ng·m-3,变化范围1.68～2961.70 ng·m-3,季节变化特征不明显.二元酸以草酸(diC2)、丙二酸(diC3)为主,浓度年均值分别为548.13ng·m-3、530.1 ng·m-3;二元酸总浓度呈明显季节变化特征,夏季最高(1539.36 ng·m-3),冬季最低(908.12 ng·m-3).4个季节碳优先指数(CPI)无显著差别,分别是15.3(秋)、12.4(冬)、11.5(春)和13.4(夏);CPI值与植物蜡贡献脂肪酸值呈现出一定的负相关.主成分分析结果表明,油烟、高等植物排放和细菌活动是脂肪酸的主要污染源,二次化学反应转化是二元酸的主要来源.     

基于生物标志物法的珠江流域有机碳溯源及DIC施肥效应研究

内源有机碳由地表水体水生光合固定DIC产生,是岩石风化碳汇的重要组成部分。为准确区分河陆地流水体中的内源有机碳及计算其所占比例,本文选取珠江流域作为研究区,通过不同季节的野外采样调查,利用类脂生物标志物法,结合传统水化学特征,揭示河流中有机碳的来源差异;最终根据有机碳的时空分布规律与水-岩-土-气-生相互作用分析,明确流域岩性及气候变化对碳汇的影响。结果表明:(1)珠江流域水体中冬季和夏季内源有机碳占总有机碳比例的平均值分别为65%和54%,表明水生植物光合作用导致的初级生产力的重要性;(2)内源有机碳比例和水生藻类生物量与DIC浓度和呈现出显著的正相关关系,表明DIC对水生植物光合作用具有施肥效应;(3)雨季因降雨稀释DIC浓度和冲刷外源有机质,对水生植物的施肥效应减弱,生成的内源有机质减少,且携带的外源有机质增加,导致内源比例减少;(4)高悬浮质(TSS)可以遮挡水体表层太阳光,减弱水生光合作用强度,降低内源有机碳的形成;但在TSS浓度比较低的情况下,其对水生植物生长繁殖的影响则体现在为其提供空间和营养物,从而增加水生藻类生物量及内源有机碳比例。     

Comparative study of microbial community structure in different filter media of constructed wetland

Comparisons of microbial community structure, in eight filter media of zeolites, anthracite, shale, vermiculite, ceramic filter media, gravel, steel slag and bio-ceramic, were undertaken by analyzing the phospholipid fatty acid (PLFA) composition. A total of 20 fatty acids in the range of C_(11) to C_(20) were determined but only 13 PLFAs were detected in steel slag. They consist of saturated fatty acids, branched fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids. The variation of fatty acids was revealed in the relative proportions of these fatty acids in different media. The aerobic prokaryotes were the predominant group in all media. The PLFA composition showed significant differences among the eight different media by Tukey's honestly test. It was found that steel slag was significantly different in the microbial community as compared to other filter media, probably due to its alkaline effluent. Steel slag alone is probably not a good choice of substratum in constructed wetlands. The principle components analysis (PCA) showed that zeolites, bio-ceramic, shale and vermiculite had a similar microbial community structure while steel slag and ceramic filter media were distinct from other media.     

雨季不同土地利用下表层岩溶泉中脂肪酸来源分析

为阐述南川表层岩溶泉中溶解性有机质的来源,采用气相色谱-质谱联用仪(GC-MS)对采自南川柏树湾(BQ)、兰花沟(LQ)、后沟(HQ)表层岩溶泉水中的脂肪酸进行定量分析.结果表明,BQ、LQ和HQ中5~7月泉水脂肪酸平均含量分别为14 870、12 912和8 801 ng·L~(-1),脂肪酸组成均表现为饱和直链脂肪酸单不饱和脂肪酸支链脂肪酸多不饱和脂肪酸,在检测到的脂肪酸中,单体脂肪酸以C16:0、C18:0含量最高,BQ、LQ、HQ中5~7月脂肪酸总浓度随时间推移呈升高趋势.各泉域植被覆盖和基岩裸露率不同,以及降雨带来的稀释作用与土壤迁移增大效应相互作用引起脂肪酸含量和组分变化.通过分析3口表层岩溶泉水中的脂肪酸分布特征和特征参数H/L、CPIh、TARFA,及细菌源、浮游植物源、陆源高等植物源脂肪酸含量发现,兰花沟泉脂肪酸5月以高等植物源为主,7月后沟泉脂肪酸以藻类来源为主,其他月的兰花沟、后沟泉、柏树湾泉的5~7月脂肪酸主要来自于细菌.     

Medium-chain fatty acids and their potential to reduce methanogenesis in domestic ruminants

In the wave of the Kyoto Protocol, a large effort is undertaken to find sustainable strategies for reducing greenhouse gas emissions from livestock. The present paper summarises the results of a research project, which was designed to analyse the potential of medium-chain fatty acids (MCFA) as a diet component for ruminants to inhibit rumen methanogenesis. In a series of eight in vitro and four in vivo experiments, a research strategy was pursued including: (i) a comparison of feeding coconut oil (rich in MCFA) and feeds containing long-chain unsaturated fatty acids (LCFA) with respect to their effects on rumen and total digestive tract metabolism; (ii) a search for effective MCFA feeds other than coconut oil; (iii) identification of specific MCFA effective against rumen methanogenesis; (iv) clarification of the mode of action of MCFA; and (v) revealing of dietary pre-conditions for a significant methane-suppressing effect of MCFA. The project clearly demonstrated the potential of MCFA, used either in esterified form (such as coconut oil, palm kernel oil and genetically modified canola oil) or in non-esterified form (C12:0 and C14:0), to substantially reduce methanogenesis in domestic ruminants. Detailed insight into the numerous interactions within the rumen, which will determine the extent of methanogenesis inhibition when feeding MCFA, was gained. From an assessment of the combined data, it was concluded that even with dietary proportions below 3% MCFA of C12:0 and C14:0, a 50% reduction of in vivo methane emission is possible.     

重庆主城区PM2.5中羧酸的季节变化和来源分析

本文针对重庆主城区4个采样点PM2.5中羧酸开展研究,通过GC-MS分析,定量分析了16种饱和脂肪酸、21种不饱和脂肪酸和8种二元羧酸等多种物质的浓度水平,进而对羧酸的季节变化及来源进行了探讨.羧酸日均总浓度为130.42~1953.79 ng·m~(-3),一元脂肪酸和二元羧酸在各采样点浓度差异显著.一元脂肪酸呈明显的季节变化,夏季最高(961.97 ng·m~(-3)),冬季最低(49.24 ng·m~(-3)).饱和脂肪酸中偶数碳优势明显,以C_(16)(棕榈酸)和C_(18)(硬脂酸)最为丰富.二元羧酸也呈明显的季节变化,在冬季最高(432.04 ng·m~(-3)),春季最低(64.57 ng·m~(-3)).二元羧酸以丙二酸、丁二酸和戊二酸为主.细菌活动和烹饪油烟对一元脂肪酸具有较大的贡献,光化学氧化作用则对二元羧酸贡献较大.     

酸-碱预处理促进剩余污泥厌氧消化的研究

为提高剩余污泥的厌氧消化效率,投加酸和碱对污泥进行预处理,对比分析了不同预处理方式（单独碱处理、酸-碱处理和碱-酸处理）对污泥水解酸化的影响,并研究了各种预处理方式对后续厌氧消化产甲烷效率的影响.结果表明,单独碱处理的溶解性化学需氧量（SCOD）溶出量比酸碱联合处理要大16%左右,预处理第8 d,达到5 406.1 mg.L-1.采用先酸（pH 4.0,4d）后碱（pH 10.0,4 d）预处理,在污泥水解酸化过程中,乙酸产量及其占总短链脂肪酸（SCFAs）的质量分数均高于其他预处理方式,其乙酸产量（以COD/VSS计）可达到74.4 mg.g-1,占总SCFAs的60.5%.酸-碱预处理后污泥混合液的C∶N比值为25左右,C∶P比值在35～40之间,这比单独碱处理和碱-酸处理后的C∶N和C∶P比值更有利于后续厌氧消化.通过对比研究发现,酸-碱预处理后,厌氧消化到第15 d,酸-碱预处理污泥的累积甲烷产量（CH4/VSS加入）达到136.1 mL.g-1,分别是空白对照、碱-酸预处理和单独碱预处理方式的2.5、1.7和1.6倍,厌氧消化效率最高.经过8 d酸-碱预处理和15 d的厌氧消化,挥发性悬浮固体（VSS）总去除率达到60.9%,污泥减量效果比其他预处理要好.很显然,酸-碱预处理方式更有利于污泥厌氧消化及污泥减量化.     

甘油投加对餐厨垃圾厌氧产酸性能的影响

餐厨垃圾厌氧发酵产生的挥发性脂肪酸（VFAs）可以作为合成聚羟基脂肪酸酯（PHA）的底物,PHA的性能与VFAs的组成密切相关.为改善PHA产品的性能,本文研究了甘油投加对餐厨垃圾产酸性能的影响.在餐厨垃圾厌氧消化半连续流反应器运行稳定的基础上,探讨了不同C/N对厌氧发酵有机物转化及VFAs产量和组成的影响.结果表明,投加甘油会降低发酵体系的pH,提高VFAs的产量,相比于对照组,C/N比为25/1时,VFAs产量提高了10.3%.C/N10.69/1（对照组）、15/1、20/1和25/1时,发酵液奇数碳VFAs所占总VFAs的比例分别为54.23%、61.16%、64.78%和66.79%.甘油的投加可以提升丙酸、戊酸等奇数碳VFAs所占比例,有利于改善PHA产品性能.     

不同深度复合垂直流人工湿地脱氮性能比较

设计构建了4套分段式复合垂直流人工湿地(IVCW)柱状模拟系统(总程分别为145,185 cm),针对低C/N型人工污水，研究基质层高、添加活性生物质及进水中氮素组成对该系统脱氮效果的影响。结果表明：当水力停留时间为1 d时，4套系统对总氮(TN)去除率均在30%以上，半程基质层设置为95 cm,不添加活性生物质的HI组对TN去除率最高，达到42%;对NH₃-N、NO^-₃-N的平均去除率分别为20%～48%、21%～66%,而NO^-₂-N在各系统中均发生了不同程度的积累。随着进水中NO^-₃-N占比负荷的增加(从1/7到6/7),其NO^-₃-N去除率整体呈下降趋势，仅HI组去除率变化较其他组更稳定。但IVCW系统加深后，添加活性生物质反而会降低其TN去除效果。IVCW系统第1段，即下行流上层单元对脱氮贡献最大，高达80%以上；不同处理间强化脱氮效果差异虽不显著，但系统后段其脱氮途径间存在一定差...     

餐饮源有机颗粒物排放特征

餐饮油烟是大气有机颗粒物的重要来源之一.本研究在深圳市内选择了西餐、茶餐厅、职工食堂和韩式料理这4种类型的餐馆,通过对这4类餐厅的外场采样,分析各类型餐厅油烟中有机颗粒物的化学组成,筛选了餐饮油烟污染源的有机特征组分.结果表明,各餐馆排放的PM_(2.5)中,有机物占60%以上.在所有定量的有机组分之中,脂肪酸含量最高,其次是二元羧酸和正构烷烃,而多环芳烃、甾醇和单糖等有机组分的含量较低.颗粒物的有机组成特征受到菜系的影响,西餐厅和韩式料理排放脂肪酸、正构烷烃和多环芳烃等有机物含量较高,但却排放了低含量的甾醇和单糖,茶餐厅和职工食堂则相反.餐饮源颗粒物中Fla/(Fla+Pyr)和LG/(Gal+Man)的比值受菜系影响较小,也区别于其他污染源的特征比值,可以作为餐饮源潜在的示踪物.餐饮源为深圳市大气颗粒物贡献了大量的脂肪酸和二元羧酸.     

边缘海环境中陆源有机质的化学生物标志物研究进展

边缘海是陆地和大洋的连接带,是陆源物质向开阔海输送的主要途径,在全球碳循环过程发挥着重要的作用。示踪边缘海沉积有机碳的来源,可以为有机碳的分布、降解、迁移和转化等研究提供基础。本文从高等植物类脂化合物(如长链正构烷烃、正构烷醇、脂肪酸、甾醇等)、维管植物木质素和土壤有机质支链和类异戊二烯四醚(BIT)等几个方面,介绍了基于化学生物标志物示踪边缘海陆源有机质来源的研究进展。指出以包含木质素、BIT等指标在内的多重示踪方法和多端元模型是指示边缘海沉积有机质来源的良好方法,能够提供比单指标方法更为准确可靠的结果。