这项研究由中国自然科学基金 (No. 91128101、41273054和 41373007) 共同出资和资助, 中国南海天然气水合物资源勘查地质调查项目 (No。DD20160211), 中央大学基础研究基金 (No. 16lgjc11), 广东省高校珠江学者资助计划 (No. 2011)。张志勇林承认中国奖学金委员会 (No. 201506380046) 提供的财政支持。扬路感谢广州精英项目 (No。JY201223) 和中国博士后科学基金 (No. 2016M592565)。我们感谢 Dr. 盛雄杨、Guangxue 和 Dr. 强对广州海洋地质调查所提供的样品和宝贵的建议。我们感谢中国科学院地质与地球物理研究所 (北京) 的 Dr. 华和 Dr., 对模拟人生的分析提供帮助。Dr. 小萍被感谢提供了中国科学院广州地球化学研究所的模拟实验室, 为这篇文章的拍摄做准备。这份手稿得益于 Dr. 艾丽莎 Dsouza 的评论, 《朱庇特》的评论编辑, 以及两位匿名的裁判。

1. 从沉积物核心收集样品 注: 核心 HS148 是从2006年在南海的沪地区的天然气水合物钻探区的一个地点获得的, 这是在 Sihao 的海洋航行中. 
<ol> <li> 将活塞核心 (此处, HS148) 从顶部到底部 (在船上) 的间隔0.7 米处切割成节, 然后将这些部分转移到冷室 (4 和 #176; C), 以便在检索后进行存储. </li>
	<li> 将核心部分转移到在陆上实验室中的冷室 (4 和 #176; C), 以便在巡航后存放。把这些部分从寒冷的房间里拿出来, 用锯子把它们纵向切成两半. </li>
	<li> 清洁沉积物表面, 并收集一组沉积物样本 (长度为15厘米; 1/4 的沉积物芯), 用小刀在整个长度范围内进行。将湿的样品单独装在拉链塑料袋中, 并用记号标记. </li>
	<li> 将湿沉积物样品 (〜30克) 放在 pre-cleaned 烧杯中, 并在40和 #176 中烘干; C 在烘干炉中为24小时。干燥后, 将沉积物分离成两个等分: 一个用于收集硫铁矿骨料 ( 即, 自黄铁矿), 另一种用于散装硫磺萃取 (见步骤 3). </li>
	<li> 将一分干沉积物放入烧杯, 加入蒸馏水以软化2小时的沉淀物. 将浆料 (包括沉淀物和烧杯中的水) 转移到用蒸馏水冲洗的0.063 毫米筛子上。
	<ol> <li> 用蒸馏水筛出沉淀物, 使所有细粒 (#60; 0.063 毫米) 都经过洗涤。收集烧杯中的粗馏分 (如: 如 、石英颗粒、化石壳和自矿物), 并在40和 #176 中烘干; 在烘干炉中进行24小时的 C. </li>
	</ol> </li> <li> 在双目显微镜下 (20X 放大倍数) 下的玻璃幻灯片上放置一些粗段分数。从粗馏分中识别黄铁矿骨料。精选这样的黄铁矿聚合使用针, 并将它们单独装入拉链塑料袋中. 
	注: 大多数硫铁矿骨料呈黑色, 管状. </li>
	<li> 将干沉积物样品的第二分粉碎成细粉 (和 #60; 0.074 毫米), 使用玛瑙砂浆进一步提取散装硫 (见步骤 3). </li>
</ol> 2。可变形态的观察 <ol> <li> 从精心挑选的黄铁矿骨料中选取一些代表性的黄铁矿管 (20X 放大倍数) 进行厚断面准备, 以检查形态学和纹理硫铁矿集料的特点. </li>
	<li> 将双面胶带粘在幻灯片上, 并将选定的黄铁矿管放在磁带上。将安装管 (直径25毫米) 放在滑轨上, 以覆盖所有的黄铁矿骨料。在室温下将10毫升的环氧树脂与1.3 毫升的固化剂混合, 将混合液倒入安装管中。
	<ol> <li> 将滑轨和安装管置于真空室中。将空气泵出燃烧室, 直到燃烧室内的压力低于 0.2 bar, 使样品的所有孔隙空间都充满环氧树脂。将滑轨和安装管移出会议厅, 并让环氧树脂固化在室温下为12小时. </li>
		<li> 环氧树脂固化后, 在固定的、9的 #181 上手工研磨硫铁矿管, 直到黄铁矿颗粒暴露。用5、3、1和 #181 对黄铁矿颗粒进行抛光, 使其表面光滑平整. </li>
	</ol> </li> <li> 在200X 放大倍数的反射光显微镜下观察黄铁矿的形貌和质地, 工作距离为3毫米. </li>
	<li> 在反射光显微镜下进行岩石观察 6 , 然后用25纳米碳层将厚剖面涂上。使用热场发射扫描电子显微镜和散射电子模式检查它们的形态和纹理特征 6 , 19 . 
	注: 这一步是在中山大学地球科学与地质工程学院进行的. </li>
</ol> 3。散装硫同位素分析 注: 总硫 (如硫化物) 被提取为硫化氢 通过 湿化学顺序提取 26 27 f 和 #252; Geologie 和 #228; ontologie、Westf 和 #228; lische Wilhelms-大学和 #228; t. #252; nster. 
<ol> <li> 将4克的干样粉末或10毫克的硫铁矿骨料每瓶放入圆底烧瓶中, 并将10毫升乙醇加入每瓶中作为催化剂。
	<ol> <li> 在500毫升的玻璃瓶中制备醋酸锌 (3%) 醋酸溶液, 以捕获硫化氢。将含醋酸锌的烧瓶连接到含有样品的烧瓶中。检查烧瓶的连接, 并将氮气冲入烧瓶中以除去空气. </li>
	</ol> </li> <li> 将20毫升 HCl 溶液 (25%) 注入到圆底烧瓶中, 使用注射器从样品中释放酸挥发性 (单) 硫化物 (AVS); 允许样品在室温下反应1小时. 
	注: 在这里, 分析表明, 没有 AVS 是目前在研究样本. </li>
	当上述反应完成时, <li> 将30毫升的1米 CrCl 2 溶液注入圆底烧瓶中; 允许样品在85和 #176 反应2小时;
	注: 铬可还原硫 (CRS, 黄铁矿) 减少到硫化氢 (H 2 ) 后的反应和沉淀作为锌硫化物在醋酸锌陷阱. </li>
	<li> 将含有硫化锌沉淀物的所有溶液转移到烧杯, 并将硫化锌沉淀物转换为硫化银 (Ag 2 S), 方法是向烧杯添加一个0.1 米 AgNO 3 解决方案。将烧杯放在加热板上, 并将其加热到90和 #176; C 使精细传播的 Ag 2 更好地凝结。
	<ol> <li> 通过过滤 (#60; 0.45 和 #181; m) 在溶液冷却到室温并在夜间在40和 #176 干燥滤液后, 收集 Ag 的 2 沉淀物; C. </li>
	</ol> </li> <li> 称200和 #181; g Ag 2 S 沉淀, 并在锡杯中混合使用等量的 V 2 O 5 。通过与元素分析仪连接的质谱仪 (EA-值) 6 , 在如此 2 分子上进行燃烧分析的硫组成. 
	注: 上述步骤是在 f 和 #252; r Geologie 与 Pal 和 #228; ontologie, Westf 和 #228; lische Wilhelms-大学和 #228; 吨和 #252; nster. </li>
</ol> 4。 原位 模拟分析 <ol> <li> 选择代表 pyr在岩石学研究之后, 从不同的沉积样品中提取出具有特征的晶体习性 ( 例如, 莓、虱子和自晶体) 的聚合体。将选定的黄铁矿骨料和索诺拉黄铁矿标准片粘在双面胶带上。模具在5毫米的中心的一个25毫米环氧安装. 
	注: 环氧盘生产工艺与步骤2.2 相同。
	<ol> <li> 在环氧树脂固化后, 在固定的9和 #181 上手工研磨圆盘; m 菱形网垫达到所需的水平, 使黄铁矿颗粒暴露。手工抛光环氧圆盘, 以产生平滑, 平坦的表面, 先后使用 5, 3, 和1和 #181; m 钻石, 这是高精度同位素比率分析所需的模拟器 28 . </li>
	</ol> </li> <li> 用去离子水和乙醇清洁环氧盘的表面。将环氧树脂盘放在镀金机中, 并将干燥的表面涂上25纳米的黄金层。
	<ol> <li> 在扫描电子显微镜下再次观察样品, 在1,000X 放大倍数下, 用9毫米的工作距离, 选择具有不同晶体习性的斑点 ( 例如, 莓、虱子和自晶体) 为模拟人生分析. 
		注: 采用高空间分辨率的硫同位素分析方法, 揭示了不同黄铁矿类型硫同位素的变异性. </li>
	</ol> </li> <li> 执行模拟分析 15 , 16 . 
	注: 在中国科学院广州地球化学研究所的模拟实验室进行。
	<ol> <li> 使用 Cs + 主离子束来测量黄铁矿的硫同位素比率 ( 34 s/ 32 s)。将 Cs + 主离子束聚焦到15和 #181; m 和 #215; 10 和 #181; m 点在10伏的能量下, 2.5 nA 电流。使用三轴向法拉第杯的同时测量 32 s, 33 和 34 s 在 multi-collector 模式, 与入口狭缝宽度60和 #181; m 和出口狭缝宽度500和 #181; m 在每个三法拉第杯子探测器. </li>
	</ol> </li> <li> 在自动序列中进行硫同位素分析, 每个分析包括三十年代的 pre-sputtering、六十年代次离子自动定心, 以及160s 的数据采集和硫同位素信号集成 (40 周期和 #215; 4 秒)。
	<ol> <li> 定期分析索诺拉黄铁矿为标准, 每 5-6 样本分析. 
		注: 见陈 et al. 19 用于更详细的分析方法和仪器参数. </li>
	</ol>
	</li>
</ol>

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Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stable+isotope+patterns+of+coexisting+pyrite+and+gypsum+indicating+variable+methane+flow+at+a+seep+site+of+the+Shenhu+area,+South+China+Sea.">Stable isotope patterns of coexisting pyrite and gypsum indicating variable methane flow at a seep site of the Shenhu area, South China Sea.</a> J Asian Earth Sci. 123, 213-223 (2016).</li><li>Virtaslo, J. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pyritic+and+baritic+burrows+and+microbial+filaments+in+postglacial+lacustrine+clays+in+the+northern+Baltic+Sea.">Pyritic and baritic burrows and microbial filaments in postglacial lacustrine clays in the northern Baltic Sea.</a> J Geol Soc London. 167 (6), 1185-1198 (2010).</li><li>Kohn, M. J., Riciputi, L. R., Stakes, D., Orange, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sulfur+isotope+variability+in+biogenic+pyrite:+Reflections+of+heterogeneous+bacterial+colonization?.">Sulfur isotope variability in biogenic pyrite: Reflections of heterogeneous bacterial colonization?.</a> Am Mineral. 83 (11-12 Pt 2), (1998).</li><li>Canfield, D. E., Raiswell, R., Westrich, J. T., Reaves, C. M., Berner, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+chromium+reduction+in+the+analysis+of+reduced+inorganic+sulfur+in+sediments+and+shales.">The use of chromium reduction in the analysis of reduced inorganic sulfur in sediments and shales.</a> Chem Geol. 54 (1-2), 149-155 (1986).</li><li>Rice, C. A., Tuttle, M. L., Reynolds, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+analysis+of+forms+of+sulfur+in+ancient+sediments+and+sedimentary+rocks:+comments+and+cautions.">The analysis of forms of sulfur in ancient sediments and sedimentary rocks: comments and cautions.</a> Chem Geol. 107 (1-2), 83-95 (1993).</li><li>Kita, N. T., Huberty, J. M., Kozdon, R., Beard, B. L., Valley, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-precision+SIMS+oxygen,+sulfur+and+iron+stable+isotope+analyses+of+geological+materials:+accuracy,+surface+topography+and+crystal+orientation.">High-precision SIMS oxygen, sulfur and iron stable isotope analyses of geological materials: accuracy, surface topography and crystal orientation.</a> Surf Interface Anal. 43 (1-2), 427-431 (2011).</li></ol>

作者没有什么可透露的。

硫铁矿的硫同位素分析是一种有用的方法, 可以帮助确定影响黄的生物地球化学过程。然而, 如果采用大容量硫同位素分析, 得到的硫同位素特征通常代表混合信号, 因为沉积黄铁矿聚集物通常是由多贯世代组成的。在这里, 我们提出了一个方法 (即,模拟人分析), 以分析原位硫同位素组成的各种黄铁矿世代的微观尺度。本协议中的关键步骤包括: (1) 从不同的沉积深度 (例如,莓、ove...

沉积物中的甲烷排放在大陆边上是常见的1,2。然而, 扩散渗流区的大部分甲烷是在沉积物中以硫酸盐为代价而氧化的, 这一过程被称为4-AOM (方程式 1)3,4。在这一过程中, 硫化物的产生通常导致黄铁矿的沉淀。此外, OSR 还通过释放硫化物 (方程式 2)5来驱动黄铁矿的形成。
CH4 +42- → HS– + 小贩3– + H2O (1)
2CH2O + 42- → H2S + 2HCO3- (2)
研究发现, 硫酸盐-甲烷过渡区 (SMTZ) 中的自硫化物揭示了高δ34的值, 这被认为是由增强引起的, 所以4-AOM 在渗透区域的范围内6,7, 8。相比之下, 由 OSR 诱导的黄铁矿通常显示较低δ34值9。然而, 这是挑战, 以确定不同的硫铁矿世代诱导的这些过程 (即, OSR, 因此4-AOM), 如果只使用一个散装硫同位素测量, 因为连续地形成了贯硫铁矿世代具有不同的同位素组成。因此, 需要进行微量的原位硫同位素分析, 以提高我们对实际矿化过程的认识10,11,12。作为一种多用途的技术为原位同位素分析, 西姆斯只需要几个微克的样本, 这引发了它的指定作为一种无损技术。一个主离子束地目标, 导致二次离子的发射, 随后被传送到质谱仪测量13。在早期的原位硫同位素分析应用中, Pimminger et al.通过使用 10-30 µm 直径光束14成功地分析了在方铅矿中的δ34值。这种方法已越来越多地应用于硫化物中硫同位素的微量分析, 在测量精度和分辨率方面都有显著的改进11,12,13,14,15,16,17,18,19,20. 从渗漏和 non-seep 环境中报告了各种形态属性和不同硫稳定同位素形态的黄铁矿, 从渗、下、21、、22、2324。然而, 我们最好的知识, 在我们最近的模拟人生研究6之前, 只有一项研究使用了原位从渗流环境中黄铁矿的硫同位素分析, 揭示了生物黄铁矿的大硫同位素变化25。
在这项研究中, 我们应用模拟人分析了自黄铁矿不同世代的δ34值从南海的渗流场, 它允许对 OSR 的微尺度判别-, 因此, 因此,4-AOM 衍生黄铁矿。

<table><tbody><tr><td>secondary ion mass spectroscopy</td><td>Cameca</td><td>IMS-1280</td><td></td></tr><tr><td>thermal field emission scanning electron microscopy</td><td>Quanta</td><td>Quanta 400F</td><td></td></tr><tr><td>elemental analyser - isotope ratio mass spectrometry</td><td>ThermoFinnigan</td><td>ThermoFinnigan Delta Plus</td><td></td></tr><tr><td>binocular microscope</td><td>any</td><td>NA</td><td></td></tr><tr><td>reflected light microscope</td><td>Carl Zeiss</td><td>3519001617</td><td></td></tr><tr><td>polishing machicine</td><td>Struers</td><td>60210535</td><td></td></tr><tr><td>cutting machicine</td><td>Struers</td><td>50110202</td><td></td></tr><tr><td>carbon/gold coating machicine</td><td>any</td><td>NA</td><td></td></tr><tr><td>ethanol</td><td>any</td><td>NA</td><td></td></tr><tr><td>acetic acid</td><td>any</td><td>NA</td><td></td></tr><tr><td>zinc acetate solution (3%)</td><td>any</td><td>NA</td><td></td></tr><tr><td>HCl solution (25%)</td><td>any</td><td>NA</td><td></td></tr><tr><td>1 M CrCl&lt;sub&gt;2&lt;/sub&gt; solution</td><td>any</td><td>NA</td><td></td></tr><tr><td>0.1 M AgNO&lt;sub&gt;3&lt;/sub&gt; solution</td><td>any</td><td>NA</td><td></td></tr><tr><td>V&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5 &lt;/sub&gt;powder</td><td>any</td><td>NA</td><td></td></tr><tr><td>pure nitrogen</td><td>any</td><td>NA</td><td></td></tr><tr><td>syringe</td><td>any</td><td>NA</td><td></td></tr><tr><td>filter(&amp;lt;0.45 &amp;micro;m)</td><td>any</td><td>NA</td><td></td></tr><tr><td>tin cups</td><td>any</td><td>NA</td><td></td></tr><tr><td>round bottom flasks</td><td>any</td><td>NA</td><td></td></tr><tr><td>epoxy</td><td>Struers</td><td>41000004</td><td></td></tr></tbody></table>

preparation of authigenic pyrite from methane-bearing sediments for in situ sulfur isotope analysis using sims

自黄铁矿的不同硫同位素组成通常是由硫酸盐驱动的甲烷厌氧氧化 (如此4-AOM) 和 organiclastic 硫酸盐还原 (OSR) 在海洋沉积物中产生的。然而, 由于不同顺序形成的黄铁矿相共存, 解开复杂的黄序列是一个挑战。这份手稿描述了一个样品制备过程, 使使用二次离子质谱 (西姆斯) 获得原位δ34S 值的各种黄铁矿世代。这使得研究人员能够约束如何使4-AOM 影响黄在含甲烷的沉积物中的含量。西姆斯分析揭示了δ34值中的一个极端范围, 从-41.6 到 + 114.8‰, 这比从相同样本的传统的块状硫同位素分析得到的δ34值范围宽得多。浅层沉积物中的黄铁矿主要由34贫化莓, 表明 OSR 早成岩形成。更深的沉积, 更多的黄铁矿发生 overgrowths 和自晶体, 其中显示更高的西姆斯δ34的值比莓。这样的34富硫黄铁矿与 AOM 在硫酸盐-甲烷过渡带, postdating OSR 的增强, 因此,4。高分辨率原位模拟程序硫同位素分析允许黄过程的重建, 这是不能通过散装硫同位素分析来解决的。

数据表达-大块硫磺同位素:
与维也纳峡谷暗黑硫 (V-CDT) 标准相比较, 其体积硫同位素比值表示, 分析精度优于±0.3‰。用国际参考材料对硫同位素测量进行了标定: IAEA-S1 (δ34s =-0.30‰), IAEA-S2 (δ34s =-21.55‰), IAEA-S3 (δ34s =-31.4‰), 和国家统计局 127 (δ34s = 20.30‰)。 
<img alt="Equation" src="/files/ftp_upload/55970...

Watch this Scientific Journal Video about Preparation of Authigenic Pyrite from Methane-bearing Sediments for In Situ Sulfur Isotope Analysis Using SIMS at JoVE.com

Preparation of Authigenic Pyrite from Methane-bearing Sediments for In Situ Sulfur Isotope Analysis Using SIMS

含甲烷沉积物中黄铁矿的硫同位素组成 (δ34) 的分析通常集中在散装样品上。在这里, 我们应用二次离子质谱分析了不同黄铁矿世代的δ34值, 以了解黄的成岩史。

原位含甲烷沉积物中自黄铁矿的制备及应用模拟器硫同位素分析

Different sulfur isotope compositions of authigenic pyrite typically result from the sulfate-driven anaerobic oxidation of methane (SO4-AOM) and ...

preparation-authigenic-pyrite-from-methane-bearing-sediments-for-situ

Research

JoVE Journal

Environment

Preparation of Authigenic Pyrite from Methane-bearing Sediments for In Situ Sulfur Isotope Analysis Using SIMS

7.6K 次观看.  Sun Yat-sen University. 含甲烷沉积物中黄铁矿的硫同位素组成 (δ34) 的分析通常集中在散装样品上。在这里, 我们应用二次离子质谱分析了不同黄铁矿世代的δ34值, 以了解黄的成岩史。

视频: Preparation of Authigenic Pyrite from Methane-bearing Sediments for In Situ Sulfur Isotope Analysis Using SIMS

Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor

The importance of microbial sulfate reduction relies on the various applications that it offers in environmental biotechnology. Engineered sulfate reduction is used in industrial wastewater treatment to remove large concentrations of sulfate along with the chemical oxygen demand (COD) and heavy metals. The most common approach to the process is with anaerobic bioreactors in which sulfidogenic sludge is obtained through adaptation of predominantly methanogenic granular sludge to sulfidogenesis. This process may take a long time and does not always eliminate the competition for substrate due to the presence of methanogens in the sludge. In this work, we propose a novel approach to obtain sulfidogenic sludge in which hydrothermal vents sediments are the original source of microorganisms. The microbial community developed in the presence of sulfate and volatile fatty acids is wide enough to sustain sulfate reduction over a long period of time without exhibiting inhibition due to sulfide. 
This protocol describes the procedure to generate the sludge from the sediments in an upflow anaerobic sludge blanket (UASB) type of reactor. Furthermore, the protocol presents the procedure to demonstrate the capability of the sludge to remove by reductive dechlorination a model of a highly toxic organic pollutant such as trichloroethylene (TCE). The protocol is divided in three stages: (1) the formation of the sludge and the determination of its sulfate reducing activity in the UASB, (2) the experiment to remove the TCE by the sludge, and (3) the identification of microorganisms in the sludge after the TCE reduction. Although in this case the sediments were taken from a site located in Mexico, the generation of a sulfidogenic sludge by using this procedure may work if a different source of sediments is taken since marine sediments are a natural pool of microorganisms that may be enriched in sulfate reducing bacteria.

Microbial sulfate reduction is a process of great importance in environmental biotechnology. The success of the sulfidogenic reactors depends among other factors on the microbial composition of the sludge. Here, we present a protocol to develop sulfidogenic sludge from hydrothermal vents sediments in a UASB reactor for reductive dechlorination purposes.

Sulfidogenic污泥海洋沉积物和三氯乙烯减少在上流式厌氧污泥床反应器开发

The importance of microbial sulfate reduction relies on the various applications that it offers in environmental biotechnology. Engineered sulfate ...

科研

环境科学

Sediment Core Sectioning and Extraction of Pore Waters under Anoxic Conditions

We demonstrate a method for sectioning sediment cores and extracting pore waters while maintaining oxygen-free conditions. A simple, inexpensive system is built and can be transported to a temporary work space close to field sampling site(s) to facilitate rapid analysis. Cores are extruded into a portable glove bag, where they are sectioned and each 1-3 cm thick section (depending on core diameter) is sealed into 50 ml centrifuge tubes. Pore waters are separated with centrifugation outside of the glove bag and then returned to the glove bag for separation from the sediment. These extracted pore water samples can be analyzed immediately. Immediate analyses of redox sensitive species, such as sulfide, iron speciation, and arsenic speciation indicate that oxidation of pore waters is minimal; some samples show approximately 100% of the reduced species, e.g. 100% Fe(II) with no detectable Fe(III). Both sediment and pore water samples can be preserved to maintain chemical species for further analysis upon return to the laboratory.

A protocol for sectioning sediment cores and extracting pore waters under anoxic conditions in order to permit analysis of redox sensitive species in both solids and fluids is presented.

沉积物核心切片和孔隙水萃取缺氧条件下

We demonstrate a method for sectioning sediment cores and extracting pore waters while maintaining oxygen-free conditions. A simple, inexpensive system is ...

Laboratory Simulation of an Iron(II)-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria

A conventional concept for the deposition of some Precambrian Banded Iron Formations (BIF) proceeds on the assumption that ferrous iron [Fe(II)] upwelling from hydrothermal sources in the Precambrian ocean was oxidized by molecular oxygen [O2] produced by cyanobacteria. The oldest BIFs, deposited prior to the Great Oxidation Event (GOE) at about 2.4 billion years (Gy) ago, could have formed by direct oxidation of Fe(II) by anoxygenic photoferrotrophs under anoxic conditions. As a method for testing the geochemical and mineralogical patterns that develop under different biological scenarios, we designed a 40 cm long vertical flow-through column to simulate an anoxic Fe(II)-rich marine upwelling system representative of an ancient ocean on a lab scale. The cylinder was packed with a porous glass bead matrix to stabilize the geochemical gradients, and liquid samples for iron quantification could be taken throughout the water column. Dissolved oxygen was detected non-invasively via optodes from the outside. Results from biotic experiments that involved upwelling fluxes of Fe(II) from the bottom, a distinct light gradient from top, and cyanobacteria present in the water column, show clear evidence for the formation of Fe(III) mineral precipitates and development of a chemocline between Fe(II) and O2. This column allows us to test hypotheses for the formation of the BIFs by culturing cyanobacteria (and in the future photoferrotrophs) under simulated marine Precambrian conditions. Furthermore we hypothesize that our column concept allows for the simulation of various chemical and physical environments &#8212; including shallow marine or lacustrine sediments.

Laboratory Simulation of an IronII-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria

We simulated a Precambrian ferruginous marine upwelling system in a lab-scale vertical flow-through column. The goal was to understand how geochemical profiles of O2 and Fe(II) evolve as cyanobacteria produce O2. The results show the establishment of a chemocline due to Fe(II) oxidation by photosynthetically produced O2.

一个铁（II）的实验室模拟的前寒武纪富海洋上升流系统探索光合细菌生长

A conventional concept for the deposition of some Precambrian Banded Iron Formations (BIF) proceeds on the assumption that ferrous iron [Fe(II)] upwelling ...

Metal-silicate Partitioning at High Pressure and Temperature: Experimental Methods and a Protocol to Suppress Highly Siderophile Element Inclusions

Estimates of the primitive upper mantle (PUM) composition reveal a depletion in many of the siderophile (iron-loving) elements, thought to result from their extraction to the core during terrestrial accretion. Experiments to investigate the partitioning of these elements between metal and silicate melts suggest that the PUM composition is best matched if metal-silicate equilibrium occurred at high pressures and temperatures, in a deep magma ocean environment. The behavior of the most highly siderophile elements (HSEs) during this process however, has remained enigmatic. Silicate run-products from HSE solubility experiments are commonly contaminated by dispersed metal inclusions that hinder the measurement of element concentrations in the melt. The resulting uncertainty over the true solubility and metal-silicate partitioning of these elements has made it difficult to predict their expected depletion in PUM. Recently, several studies have employed changes to the experimental design used for high pressure and temperature solubility experiments in order to suppress the formation of metal inclusions. The addition of Au (Re, Os, Ir, Ru experiments) or elemental Si (Pt experiments) to the sample acts to alter either the geometry or rate of sample reduction respectively, in order to avoid transient metal oversaturation of the silicate melt. This contribution outlines procedures for using the piston-cylinder and multi-anvil apparatus to conduct solubility and metal-silicate partitioning experiments respectively. A protocol is also described for the synthesis of uncontaminated run-products from HSE solubility experiments in which the oxygen fugacity is similar to that during terrestrial core-formation. Time-resolved LA-ICP-MS spectra are presented as evidence for the absence of metal-inclusions in run-products from earlier studies, and also confirm that the technique may be extended to investigate Ru. Examples are also given of how these data may be applied.

We present a procedure to determine the metal-silicate partitioning of siderophile elements, emphasizing techniques that suppress the formation of metal inclusions in experiments for the noble metals. The results of these experiments are used to demonstrate the effect of core-formation on the highly siderophile element composition of the mantle.

金属硅酸盐分区在高压和高温:实验方法和协议，以抑制高亲铁元素元素夹杂物

Estimates of the primitive upper mantle (PUM) composition reveal a depletion in many of the siderophile (iron-loving) elements, thought to result from ...

化学

In Situ Characterization of Shewanella oneidensis MR1 Biofilms by SALVI and ToF-SIMS

Bacterial biofilms are surface-associated communities that are vastly studied to understand their self-produced extracellular polymeric substances (EPS) and their roles in environmental microbiology. This study outlines a method to cultivate biofilm attachment to the System for Analysis at the Liquid Vacuum Interface (SALVI) and achieve in situ chemical mapping of a living biofilm by time-of-flight secondary ion mass spectrometry (ToF-SIMS). This is done through the culturing of bacteria both outside and within the SALVI channel with our specialized setup, as well as through optical imaging techniques to detect the biofilm presence and thickness before ToF-SIMS analysis. Our results show the characteristic peaks of the Shewanella biofilm in its natural hydrated state, highlighting upon its localized water cluster environment, as well as EPS fragments, which are drastically different from the same biofilm's dehydrated state. These results demonstrate the breakthrough capability of SALVI that allows for in situ biofilm imaging with a vacuum-based chemical imaging instrument.

In Situ Characterization of Shewanella oneidensis MR1 Biofilms by SALVI and ToF-SIMS

This article presents a method for growing a biofilm for in situ time-of-flight secondary ion mass spectrometry for chemical mapping in its hydrated state, enabled by a microfluidic reactor, System for Analysis at the liquid Vacuum Interface. The Shewanella oneidensis MR-1 with green fluorescence protein was used as a model.

原位萨尔和 TOF-SIMS希瓦氏菌 oneidensis MR1 生物膜的表征

Bacterial biofilms are surface-associated communities that are vastly studied to understand their self-produced extracellular polymeric substances (EPS) ...

Simulation of Early Earth Hydrothermal Chimneys in a Thermal Gradient Environment

Deep sea hydrothermal vents are self-organizing precipitates generated from geochemical disequilibria and have been proposed as a possible setting for the emergence of life. The growth of hydrothermal chimneys in a thermal gradient environment within an early Earth vent system was successfully simulated by using different hydrothermal simulants, such as sodium sulfide, which were injected into an early Earth ocean simulant containing dissolved ferrous iron. Moreover, an apparatus was developed to sufficiently cool the ocean simulant to near 0 &#176;C in a condenser vessel immersed in a cold water bath while injecting a sulfide solution at hot to room temperatures, effectively creating an artificial chimney structure in a temperature gradient environment over a period of a few hours. Such experiments with different chemistries and variable temperature&#160;gradients resulted in a variety of morphologies in the chimney structure. The use of ocean and hydrothermal fluid simulants at room temperature resulted in vertical chimneys, whereas the combination of a hot hydrothermal fluid and cold ocean simulant inhibited the formation of robust chimney structures. The customizable 3D printed condenser created for this study acts as a jacketed reaction vessel that can be easily modified and used by different researchers. It will allow the careful control of injection rate and chemical composition of vent and ocean simulants, which should help accurately simulate prebiotic reactions in chimney systems with thermal gradients similar to those of natural systems.

The goal of this protocol is to form simulated hydrothermal chimneys via chemical garden injection experiments and introduce a thermal gradient across the inorganic precipitate membrane, using a 3D printable condenser that can be reproduced for educational purposes.

热梯度环境中早期地球热液烟囱的模拟

Deep sea hydrothermal vents are self-organizing precipitates generated from geochemical disequilibria and have been proposed as a possible setting for the ...

A Method to Preserve Wetland Roots and Rhizospheres for Elemental Imaging

Roots extensively interact with their soil environment but visualizing such interactions between roots and the surrounding rhizosphere is challenging. The rhizosphere chemistry of wetland plants is particularly challenging to capture because of steep oxygen gradients from the roots to the bulk soil. Here a protocol is described that effectively preserves root structure and rhizosphere chemistry of wetland plants through slam-freezing and freeze drying. Slam-freezing, where the sample is frozen between copper blocks pre-cooled with liquid nitrogen, minimizes root damage and sample distortion that can occur with flash-freezing while still minimizing chemical speciation changes. While sample distortion is still possible, the ability to obtain multiple samples quickly and with minimal cost increases the potential to obtain satisfactory samples and optimizes imaging time. The data show that this method is successful in preserving reduced arsenic species in rice roots and rhizospheres associated with iron plaques. This method can be adopted for studies of plant-soil relationships in a wide variety of wetland environments that span concentration ranges from trace-element cycling to phytoremediation applications.

We describe a protocol to sample, preserve, and section intact roots and the surrounding rhizosphere soil from wetland environments using rice (Oryza sativa L.) as a model species. Once preserved, the sample can be analyzed using elemental imaging techniques, such as synchrotron X-ray fluorescence (XRF) chemical speciation imaging.

元素成像保护湿地根和岩石圈的方法

Roots extensively interact with their soil environment but visualizing such interactions between roots and the surrounding rhizosphere is challenging. The ...

Separation of Uranium and Thorium for 230Th-U Dating of Submarine Hydrothermal Sulfides

The age of a submarine hydrothermal sulfide is a significant index for estimating the size of hydrothermal ore deposits. Uranium and thorium isotopes in the samples can be separated for 230Th-U dating. This article presents a method to purify and separate U and Th isotopes in submarine hydrothermal sulfide samples. Following this technique, the separated U and Th fractions can meet measuring requirements by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS). The age of the hydrothermal sulfide sample can be calculated by measuring the present-day activity ratios of 230Th/238U and 234U/238U. A super clean room is necessary for this experiment. Cleaned regents and supplies are used to reduce the contamination during the sample processes. Balance, hotplate, and centrifuge are also used. The sulfide sample is powdered for analysis and less than 0.2 g sample is used. Briefly, the sample is weighed, dissolved, added to 229Th-233U-236U double spike solution, Fe co-precipitated, and separated on an anion-exchange resin extraction column. Approximately 50 ng U is consumed for 230Th-U dating of sulfides sample by MC-ICPMS.

Separation of Uranium and Thorium for 230Th-U Dating of Submarine Hydrothermal Sulfides

The protocol describes a method to purify and separate the U and Th nuclide in submarine hydrothermal sulfide sample with Fe co-precipitation and extraction chromatography for 230Th-U disequilibrium dating.

海底热液硫化物230Th-U测定铀和铀的分离

The age of a submarine hydrothermal sulfide is a significant index for estimating the size of hydrothermal ore deposits. Uranium and thorium isotopes in ...

Using Flexible Gold-Titanium Reaction Cells to Simulate Pressure-Dependent Microbial Activity in the Context of Subsurface Biomining

Laboratory studies investigating subsurface microbial processes, such as metal leaching in deep ore deposits (biomining), share common and challenging obstacles, including the special environmental conditions that need to be replicated, e.g., high pressure and in some cases acidic solutions. The former requires an experimental setup suitable for pressurization up to 100 bar, while the latter demands a fluid container with high chemical resistance against corrosion and unwanted chemical reactions with the container wall. To meet these conditions for an application in the field of in situ biomining, a special flexible gold-titanium reaction cell inside a rocking high-pressure reactor was used in this study. The described system allowed simulation of in situ biomining through sulfur-driven microbial iron reduction in an anoxic, pressure-controlled, highly chemically inert experimental environment. The flexible gold-titanium reaction cell can accommodate up to 100 mL of sample solution, which can be sampled at any given time point while the system maintains the desired pressure. Experiments can be performed on timescales ranging from hours to months. Assembling the high-pressure reactor system is fairly time consuming. Nevertheless, when complex and challenging (microbiological) processes occurring in the earth&#39;s deep subsurface in chemically aggressive fluids have to be investigated in the laboratory, the advantages of this system outweigh the disadvantages. The results found that even at high pressure the microbial consortium is active, but at significantly lower metabolic rates.

This protocol describes microbial experiments under elevated pressures to study in situ biomining processes. The experimental approach employs a rocking high-pressure reactor equipped with a gold-titanium reaction cell containing a microbial culture in an acidic, iron-rich medium.

使用柔性金钛反应细胞在地下生物采矿环境中模拟压力依赖微生物活性

Laboratory studies investigating subsurface microbial processes, such as metal leaching in deep ore deposits (biomining), share common and challenging ...

工程学

Biological Samples Preparation for Speciation at Cryogenic Temperature using High-Resolution  X-Ray Absorption Spectroscopy

The study of elements with X-ray absorption spectroscopy (XAS) is of particular interest when studying the role of metals in biological systems. Sample preparation is a key and often complex procedure, particularly for biological samples. Although X-ray speciation techniques are widely used, no detailed protocol has been yet disseminated for users of the technique. Further, chemical state modification is of concern, and cryo-based techniques are recommended to analyze the biological samples in their near-native hydrated state to provide the maximum preservation of chemical integrity of the cells or tissues. Here, we propose a cellular preparation protocol based on cryo-preserved samples. It is demonstrated in a high energy resolution fluorescence detected X-ray absorption spectroscopy study of selenium in cancer cells and a study of iron in phytoplankton. This protocol can be used with other biological samples and other X-ray techniques that can be damaged by irradiation.

This protocol presents a detailed procedure to prepare biological cryosamples for synchrotron-based X-ray absorption spectroscopy experiments. We describe all the steps required to optimize sample preparation and cryopreservation with examples of the protocol with cancer and phytoplankton cells. This method provides a universal standard of sample cryo-preparation.

使用高分辨率X射线吸收光谱在低温下制备生物样品以进行形态分析

The study of elements with X-ray absorption spectroscopy (XAS) is of particular interest when studying the role of metals in biological systems. Sample ...