Name: sediment core sectioning and extraction of pore waters under anoxic conditions
Uploaded: 2016-03-07T13:00:00.000+00:00
Duration: 9 min 21 s
Description: Watch this Scientific Journal Video about Sediment Core Sectioning and Extraction of Pore Waters under Anoxic Conditions at JoVE.com

这项研究部分由美国国家科学基金会的快速程序（NSF-1048925，1048919，和1048914）艾莉森Keimowitz，明郭李笃Okeke，和詹姆斯·桑德斯的支持。

1.设备的研制<ol><li>核心内衬的制备<ol><li>计算将使用卷来获得核心片=πR2×厚度厚度;最终的体积必须&lt;50 立方厘米 。用10cm的纤芯直径，可以得到2厘米厚的片。 注意:这是没有必要具有体积是一个完整的50毫升，但得到的孔隙水体积将成比例越小。 </li><li>使用线锯（或类似的）切片一个芯衬垫，或相同直径的塑料管，成2厘米的环（或其它的厚度，如果使用不同的直径芯）。获得3-5环。 </li><li>清洁所有的塑料材料会在接触沉积物，包括核心套，瓶盖核心，戒指，核心切片机，离心管，注射器，和一次性勺子。 （浸泡的塑料材料，在10％HCl中24小时后，冲洗塑料材料nanopure（22兆欧）水3倍，并且允许材料在空气中干燥，优选在层流罩，包装前）。 </li></ol></li><li>杰克实验室制备<ol><li>切下一块胶合板的，采用线锯，以覆盖实验室千斤顶的顶板的6"×6"的大小，并在使用空穴这个夹板的中心钻一个孔锯安装到钻。 注意:这个洞应该只是比PVC扩片直径略大;对于这里使用的尺寸，孔应该是2.75"。 </li><li>钻四个在此夹板的边缘小孔上使用一个手电钻或钻床常规钻头以匹配实验室千斤顶的顶板上的孔。拧紧夹板用扎带实验室插孔。 注:应该有这个夹板没有"回旋"。 </li></ol></li><li>钻在约2&#39;×1.5&#39;胶合板比使用孔锯芯衬垫的外径稍大的中心的孔。对于直径10厘米的核心班轮，一个10.5-11.5厘米的洞会appropria德。这种木材是核心指导板。 </li><li>芯挤压机的制备（活塞） <ol><li>获得完全吻合核心衬里内的橡胶塞的实验室。如果没有可用的，用剃刀刮胡子之一大小。不要使用过小的瓶塞。 </li><li>螺杆实验室塞子约1&#39;-1.5"长，1"直径的木钉或用扫帚柄，与防水绝缘胶带塞子的面盖螺丝头。 注意:动器的较大的面应在销了。 </li></ol></li><li>切PVC管的约1.5&#39;长成〜6"长部分。 注:内部直径应比在步骤1.4.2销钉较大，但比在步骤1.4.1止动小。这个协议假定使用标准2"的PVC的2.375真正的外径。"这些PVC片是核心扩展。 </li><li>装配在材料清单中列出的所有其他必要的设备。 注:此SH乌尔德在家庭实验室中收集并带​​到野外实验室。 </li></ol> 2.设置场站实验室<ol><li>建立手套袋<ol><li>夹紧芯引导板的工作表面（台面，实验室表面等 ）。确保为核心班轮孔是在工作面上，而且是开放的。 </li><li>将在核心导向板一次性手套包，并运行从手套包管道进入到N 2坦克的调节器上的管道。确保燃油箱是用气缸板凳钳牢牢固定。 </li><li>大盘油管手套袋由环绕周围袋用电工胶带管道的外部封住这个入口点。确保约8"管延伸入手套袋的内部的管夹滑到手套袋内的管道;离开该夹紧开放。 </li><li>在手套袋在底部切一个"X"孔用一个盒子刀或直剃刀的核心指导板。这个x应大于芯衬垫直径小。 </li><li>加载与表1中找到的项的手套袋中。 </li></ol></li><li>建立核心<ol><li>将实验室插孔，其中手套包贴在工作区下方的地板上。放置芯通过在手套袋的底部，在步骤2.1.4的"X"切，保持在直立位置。 注:约4-6"的核心应该扩展核心稳定板之上。 </li><li>保持核心稳定，让研究人员2至2.2.6执行步骤2.2.3。 </li><li>磁带核心的塑料手套袋围绕"X"，用大量的密封性好电工胶带。 </li><li>插入，芯挤压机的手柄成"直径，〜6"2 PVC长垫片，随后〜3"长耦合，接着另一个垫片。继续这种模式，直到PVC完全盖手柄;它可以延伸短的距离近的手柄的端部。放置芯挤压机（与PVC间隔件和联接器）的核心的底部的下方。 </li><li>支持核心挤出机实验室千斤顶使挤出机可以支持的核心。此时，保持插座尽可能低，并使用核心隔板尽可能。 </li><li>使用一箱刀围绕底部核心帽精心切割。该切口应当导致芯盖的环留围绕芯衬套的外部和芯盖的代替对芯材的平坦圆形部分。 </li><li>将手放入手套袋（研究员1）。持芯稳定，使得它不会在芯稳定板之上更进一步移动，而研究员2开始转动实验室千斤顶慢慢提高的核心。核心挤出机应该进入核心班轮，并开始推泥沙像向上推弹出。 </li><li>扭动芯挤压机侧小幅如果东北侧EDED将其插入到所述芯衬垫（研究员2）。对于轻微的流行，当它进入做好准备。 </li><li>继续提高芯直到芯材料的顶部处或附近的芯衬垫的顶部（研究者1和2）。请注意，核心上限应在此过程中保持在芯的顶上。 </li></ol></li><li>密封袋手套<ol><li>仔细检查所有必需的生活用品在手套袋;打开便携式氧计。 </li><li>开所有离心管，水瓶，以及包含截留的空气的其他项目。如果核心有积水上面顶空，打开顶盖以清除这个顶部空间。 </li><li>打开调节器，使氮的通过管的流动到手套袋以中等速度。一般一个在所有阀门打开为宜最后调节器级〜15磅的压力。 注:这应该是速度不够快，感觉就像皮肤上强风，但不是那么强大，它驱散手套袋SUP层数。 </li><li>点入氮气手套袋的各个领域，并推动了氮的主要开放的最好的一个人的能力。关掉氮气。 </li><li>通过重复步骤2.3.6至2.3.9三次吹扫手套袋中三次。 注意:一个人可以做到这一点，但它可能对两个人更容易，使人们可以保持他或她的手在属于手套袋的一部分的手套。 </li><li>通过围绕其1-2蹦极绳索几次封袋手套的主要开幕。打开氮气的类似流如在2.3.3。地方研究员1的手在手套袋内置手套。 </li><li>从袋的一个区域移动至氮气管到另一个填充氮气的手套袋中。点管子插入任何缝隙，如打开离心管中，水在上面喷瓶， 等等。 </li><li>通过关闭管夹关掉氮气。注意，这可以在不除去水库来完成earcher 1的手从手套包。 </li><li>打开手套袋的前面，并使用研究者1的身体，推尽可能多的气体从袋子尽可能的。 注:包应该在这一点上是它里面的周边耗材持平。 </li><li>填充手套袋到舒适的压力和使用的管夹关掉氮气。一些试验和错误可能需要找到舒适的压力，因为太满，这是难以移动一个人的手臂，而太空，这是很难看到并操纵对象。打开短期内重新填充袋，如果它似乎有一个缓慢的泄漏或越来越以任何理由空虚氮管夹。打开包的前面，让出少量的氮气，如果它变得不舒服满。 </li><li>检查溶解氧在便携式氧计的水平。它应该是在1％以下。 </li><li>将手套袋手套到一次性手套。这将提高灵活性。改变他们时，他们GEŧ污渍或损坏;丢弃在袋中的废弃物容器中。 </li></ol></li></ol> 3.切片核心注:该过程的这个部分更容易与两位研究者来完成。 <ol><li>除去使用注射器积水。注射器过滤这种水并放入50ml离心管中。 </li><li>删除一个核心部分， <ol><li>上方放置芯衬垫的顶部的芯切片环。提高核心起来（第3.3节），直到沉淀物的顶部是在环的顶部。 </li><li>插入芯衬垫和环的顶部之间的芯切片机。沉积物部分现在坐的核心切​​片机顶上。 </li><li>移动使用一次性勺子沉积物至50ml管中。帽管紧，一旦它充满。 </li><li>冲洗核心切片机和核心切片环与超纯水;喷脏废为手套袋内废物容器。一次性勺子也可以冲洗，或丢弃，这取决于所需要的数量。擦干核心切片机切片核心环纸巾。 </li><li>重复步骤3.2直到没有进一步的芯材依然存在。 </li></ol></li><li>提高核心<ol><li>贯穿3.2有必要提高的核心。在使用实验室千斤顶小的增量执行此操作。执行以下三个步骤一次实验室千斤顶完全展开。 </li><li>握住手套袋（研究员1）代替的核心。 </li><li>放下实验室插孔最低设置，当它被完全压缩（研究员2）。确保核心是与手套包和研究员2的双手从下方支持在研究1的手的地方举行。 </li><li>填充芯挤压机的底端和与PVC间隔件和管件的插孔之间的空间。确保核心是由核心扩展让核心的顶部走之前牢固地支撑。 </li></ol></li></ol> 4.惠tracting孔隙水<ol><li>打开手套袋并取出离心管的机架。 </li><li>根据需要通过消灭纸巾，水等空废物容器内取出任何土壤，液体或冷凝清理杂物袋。 </li><li>用蹦极绳索松散重新密封手套袋中。 </li><li>权衡其现在包含剖开的沉积物（如需要）离心管中。 </li><li>包住离心管的顶部用绝缘带密封的盖/管交界处。 </li><li>用胶带后称重来平衡离心管。添加或删除电工胶带至0.5g中得到的权重。 注意:通常情况下，从芯部的顶部管会比从底部打火机。 </li><li>在离心机和离心以最大加速度地方管（推荐1100 XG）20分钟。 注意:较高的利率离心将允许孔隙水的分离较大。 </li><li>从centrifu删除电工胶带戈管或者通过unpeeling或通过与之前的管返回到手套袋中的剃刀切割。返回离心管离心后机架，并返回到手套袋中。 </li><li>添加另一组离心管，注射器和注射器过滤器到手套袋中。这些新的管将持有孔隙水和可预先标记。 </li><li>再次清除手套塑料袋，在步骤2.3.5。如果手套袋只简单地打开，取出管，未清洁的，这将是可接受的清除它只有两次。如果正在使用氧气监视器，保证在手套袋中的气氛&lt;1％O 2。不要忘了打开新添加的离心管和清除它们。 </li><li>双手插在手套袋手套;和以前一样，请用一次性手套。 </li><li>打开一管。从使用注射器沉积物上方取出孔隙水，然后用注射器过滤器附加到注射器的尖端。如果孔隙水和沉积物很好的分离，porewat器可以直接倒入取下筒与上尖端的注射器过滤器的注射器。 </li><li>通过注射过滤器推水到适当的离心管中。 注:将需要一些力量;可能需要每个样品多于一个针筒过滤器。 </li><li>替换在含有沉积物和含有孔隙水管内的离心管的盖子。 </li><li>对每个样品重复步骤4.13 4.15通过。 </li><li>打开手套袋中，取出样品。既沉积物和孔隙水管可以重新称重。 </li><li>如果需要立即分析孔隙水。分析可包括（但不限于）为主要离子11离子色谱，菲洛嗪铁形态12中 ，砷的形态由伏安13和硫化物形态14。 </li><li>在冷冻干燥托运人孔隙水和沉积物（约-80℃）保存形态为在适当分析后为计划的分析。据米也AY适当样本保持在密闭容器中或氮气吹扫镀铝袋冷却。 </li><li>再利用的手套袋中的第二芯如果需要的话（在2.2.2开始）。两个芯后，将手套袋中通常需要改变。 </li></ol>

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D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spectrophotometric+Determination+of+Hydrogen+Sulfide+in+Natural+Waters.">Spectrophotometric Determination of Hydrogen Sulfide in Natural Waters.</a> L&amp;O. 14, 454-458 (1969).</li></ol>

本文所描述的技术是一种灵活的，能够为各种各样的位置，芯尺寸，芯部厚度等 ，有此系统的三个主要组分进行调整。 首先，准备正确尺寸的芯挤压系统，用于将待分析的核心。这里给出的说明假设一个大约30"芯;长得多芯可能需要更多的PVC增量剂件和PVC管件完全挤出如本领域的更正是困难得多管理计划的挤压系统和仔细的包装，。 其次，确保手?...

研究人员常常希望来研究沉积物 - 水系统的氧化还原状态和地质微生物学。这理想地利用来自两个沉积物和孔隙水的数据，孔隙水通常是系统的敏感显示器和是一个公共源，虽然不是唯一的源，生态暴露于氧化还原敏感性重金属1如砷和铀。孔隙水数据可以原位使用扩散平衡滤波器，也称为"皮珀斯，"安装到沉积物2来获得。偷窥者都在外地网站之前开始现场工作，并在那里过的很长一段时间多次访问可以到野外现场进行， 例如 Shotyk 3闻名设置最常用的。因此，许多情况下不允许使用皮珀斯，如站点只有很短的时间内可以访问或者获得多个探样品，以确定进一步的调查应该发生4。此外皮珀斯不同时采样沉积物水样采集。 当希望采样沉淀物和水一起，或在该领域网站，偷窥安装是不可行的，最常用的方法，以获得沉淀物和水是沉积物核化。获得未混合芯是一个关键的前体在此工作5描述的过程。一旦获得芯孔隙水可以通过挤压6或离心来获得;都具有优点和缺点。离心通常被认为是提取沉积物岩芯，7孔隙水虽然必须小心，以防止或沉积物孔隙水的氧化最可靠的方法。 在这种方法中，我们描述的核心挤出和离心提取孔隙水以最小的氧化。作者使用在各种上下文包括海洋8的本文中所描述的方法中，被污染的湖泊<sup&gt; 9，和湿地10。示出的具有代表性的数据表明，在还原条件得以保存。用离心机之外，使用的材料是廉价的，而且这种方法可以适用于各种各样的地球化学和地球微生物研究问题。

<table><tbody><tr><td>Disposable glove bag(s)</td><td>Sigma-Aldrich</td><td>Z106089-1EA</td><td>One per two cores to be processed is usually sufficient.</td></tr><tr><td>N&lt;sub&gt;2&lt;/sub&gt; tank</td><td>Praxair</td><td></td><td>Often gas supply companies can deliver these directly to the field laboratory.</td></tr><tr><td>Nitrogen gas regulator</td><td>VWR</td><td>55850-478</td><td>Or similar</td></tr><tr><td>Several feet of tubing that fits the regulator</td><td>VWR</td><td>89403-862</td><td>Or similar</td></tr><tr><td>Safety equipment to secure the tank</td><td>VWR</td><td>60142-006</td><td></td></tr><tr><td>Adjustable tubing clamp</td><td>VWR</td><td>62849-112</td><td></td></tr><tr><td>Waterproof, good sealing electrical tape</td><td>Scotch</td><td>Super 33+</td><td>Widely available</td></tr><tr><td>2-4 short bungee cords</td><td></td><td></td><td>Widely available</td></tr><tr><td>Squirt bottles of nanopure water</td><td>VWR</td><td>16650-082</td><td>Any similar bottle is fine; pack an additional supply of nanopure water to refill these.</td></tr><tr><td>Large supply of paper towels and Kimwipes</td><td></td><td></td><td>Widely available</td></tr><tr><td>50 ml centrifuge tubes</td><td>VWR</td><td>21008-951</td><td>Acid cleaned as described in protocol. At least 2/core section needed.</td></tr><tr><td>Several permanent in markers.</td><td></td><td></td><td>Widely available</td></tr><tr><td>Several straight razor blades and box cutters.</td><td></td><td></td><td>Widely available</td></tr><tr><td>Centrifuge</td><td>Beckman-Coulter</td><td>Allegra X-22</td><td>Faster rotor allows greater separation.</td></tr><tr><td>Rotor to accommodate 50 ml tubes</td><td>Beckman-Coulter</td><td>SX-4250</td><td></td></tr><tr><td>50 ml plastic syringes without black rubber tip on the barrel</td><td>VWR</td><td>66064-764&amp;nbsp;</td><td>Acid cleaned as described in protocol. At least 1/core section needed, plus 1 for overlying water.</td></tr><tr><td>Syringe filters compatible with aqueous solutions.</td><td>VWR</td><td>28143-310&amp;nbsp;</td><td>Either 0.45 &amp;mu;m or 0.20&amp;nbsp;&amp;mu;m poresizes may be used. Plan on five filters per core section processed.</td></tr><tr><td>Plastic (disposable) spoons.</td><td></td><td></td><td>Widely available; Acid cleaned as described in protocol.</td></tr><tr><td>Several boxes of disposable gloves.</td><td></td><td></td><td>Widely available</td></tr><tr><td>Large plastic beakers or other waste containers to place in the glove bag.</td><td>VWR</td><td>13890-148</td><td></td></tr><tr><td>Laboratory balance</td><td>VWR</td><td>10205-008</td><td>An available balance will be fine; high precision not required</td></tr><tr><td>Dry shipper, pre-charged with liquid nitrogen</td><td>VWR</td><td>82005-416</td><td>Needed only if samples are being returned to the home laboratory for sensitive analyses.</td></tr><tr><td>Laboratory notebooks</td><td></td><td></td><td>Water repellent can be useful</td></tr><tr><td>Core liners</td><td>Watermark</td><td>77280</td><td>Available from Forrestry Suppliers</td></tr><tr><td>Core caps</td><td>Ben Meadows</td><td>218105</td><td></td></tr><tr><td>Core slicers</td><td>McMaster Carr</td><td>8707K111</td><td>Cut this into 9 3 x 3 squares</td></tr><tr><td>PVC spacers</td><td>McMaster Carr</td><td>48925K96</td><td>Cut this into short lengths</td></tr><tr><td>PVC couplings</td><td>McMaster Carr</td><td>4880K76</td><td>Approximately 12 needed</td></tr><tr><td>Dowel</td><td></td><td></td><td>Widely available</td></tr><tr><td>Lab stopper</td><td>VWR</td><td>59580-400</td><td>Check to ensure the correct size to fit snugly within the core liners</td></tr><tr><td>Plywood for core guidance plate and top of lab jack</td><td></td><td></td><td>Widely available</td></tr><tr><td>Lab jack</td><td>VWR</td><td>89260-826</td><td></td></tr><tr><td>Clamps</td><td></td><td></td><td>Widely available</td></tr><tr><td>Portable oxygen monitor</td><td>RKI instruments</td><td>OX-07</td><td></td></tr></tbody></table>

sediment core sectioning and extraction of pore waters under anoxic conditions

我们演示了切片沉积岩芯和提取孔隙水，同时保持无氧状态的方法。一个简单，廉价的系统构建，可以运到一个临时的工作空间接近现场采样网站（），以方便快速分析。芯被挤压成一个便携式手套袋中，在那里它们被切片并每1-3厘米厚的部分（取决于芯直径）被密封到50ml离心管中。孔隙水用离心分离的手套袋中的外面，然后返回到手套袋用于从沉淀分离。这些提取出来的孔隙水样品可立即进行分析。氧化还原敏感的物种，如硫化物，铁形态，和砷的形态的直接分析表明孔隙水的氧化最小;一些样品显示没有可检测的Fe（III）还原物种的约100％， 例如 100％的Fe（Ⅱ）。这两种沉积物和孔隙水样可以保存到主一旦返回到实验室覃用于进一步分析的化学物质。

<html>类型获得的结果取决于所执行的分析和对从其获得芯地球化学设置。溶解氧可以在所提取的孔隙水进行测量，但在很多情况下，这将是下面的芯的前几个厘米为零。通常提供更多有意义的信息的分析包括铁形态（铁II / III铁）12，砷的形态（如III /作为V）13，和硫化物14。还原物质如硫化物的存在指示既还原环境和足够缺氧芯切片期间维持和孔?...

Watch this Scientific Journal Video about Sediment Core Sectioning and Extraction of Pore Waters under Anoxic Conditions at JoVE.com

Sediment Core Sectioning and Extraction of Pore Waters under Anoxic Conditions

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 ...

sediment-core-sectioning-extraction-pore-waters-under-anoxic

Research

JoVE Journal

Environment

8.9K 次观看.  Vassar College. 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.

视频: Sediment Core Sectioning and Extraction of Pore Waters under Anoxic Conditions

Laboratory-determined Phosphorus Flux from Lake Sediments as a Measure of Internal Phosphorus Loading

Eutrophication is a water quality issue in lakes worldwide, and there is a critical need to identify and control nutrient sources. Internal phosphorus (P) loading from lake sediments can account for a substantial portion of the total P load in eutrophic, and some mesotrophic, lakes. Laboratory determination of P release rates from sediment cores is one approach for determining the role of internal P loading and guiding management decisions. Two principal alternatives to experimental determination of sediment P release exist for estimating internal load: in situ measurements of changes in hypolimnetic P over time and P mass balance. The experimental approach using laboratory-based sediment incubations to quantify internal P load is a direct method, making it a valuable tool for lake management and restoration.
Laboratory incubations of sediment cores can help determine the relative importance of internal vs. external P loads, as well as be used to answer a variety of lake management and research questions. We illustrate the use of sediment core incubations to assess the effectiveness of an aluminum sulfate (alum) treatment for reducing sediment P release. Other research questions that can be investigated using this approach include the effects of sediment resuspension and bioturbation on P release.
The approach also has limitations. Assumptions must be made with respect to: extrapolating results from sediment cores to the entire lake; deciding over what time periods to measure nutrient release; and addressing possible core tube artifacts. A comprehensive dissolved oxygen monitoring strategy to assess temporal and spatial redox status in the lake provides greater confidence in annual P loads estimated from sediment core incubations.

Lake eutrophication is a water quality issue worldwide, making the need to identify and control nutrient sources critical. Laboratory determination of phosphorus release rates from sediment cores is a valuable approach for determining the role of internal phosphorus loading and guiding management decisions.

实验室确定的磷通量湖泊沉积物作为内部磷载入一个测量

Eutrophication is a water quality issue in lakes worldwide, and there is a critical need to identify and control nutrient sources. Internal phosphorus (P) ...

科研

环境科学

The Benthic Exchange of O2, N2 and Dissolved Nutrients Using Small Core Incubations

The measurement of sediment-water exchange of gases and solutes in aquatic sediments provides data valuable for understanding the role of sediments in nutrient and gas cycles. After cores with intact sediment-water interfaces are collected, they are submerged in incubation tanks and kept under aerobic conditions at in situ temperatures. To initiate a time course of overlying water chemistry, cores are sealed without bubbles using a top cap with a suspended stirrer. Time courses of 4-7 sample points are used to determine the rate of sediment water exchange. Artificial illumination simulates day-time conditions for shallow photosynthetic sediments, and in conjunction with dark incubations can provide net exchanges on a daily basis. The net measurement of N2 is made possible by sampling a time course of dissolved gas concentrations, with high precision mass spectrometric analysis of N2:Ar ratios providing a means to measure N2 concentrations. We have successfully applied this approach to lakes, reservoirs, estuaries, wetlands and storm water ponds, and with care, this approach provides valuable information on biogeochemical balances in aquatic ecosystems.

The Benthic Exchange of O2, N2 and Dissolved Nutrients Using Small Core Incubations

Here, we present small core incubations for the measurement of sediment-water gas and solute exchange. These will provide reliable measurements of sediment-water exchange that assess the role of sediment in influencing biological and biogeochemical processes in aquatic ecosystems.

Ø的底栖交易所<sub&gt; 2</sub&gt;，N<sub&gt; 2</sub&gt;和营养盐使用小的核心孵化

The measurement of sediment-water exchange of gases and solutes in aquatic sediments provides data valuable for understanding the role of sediments in ...

Soil Lysimeter Excavation for Coupled Hydrological, Geochemical, and Microbiological Investigations

Studying co-evolution of hydrological and biogeochemical processes in the subsurface of natural landscapes can enhance the understanding of coupled Earth-system processes. Such knowledge is imperative in improving predictions of hydro-biogeochemical cycles, especially under climate change scenarios. We present an experimental method, designed to capture sub-surface heterogeneity of an initially homogeneous soil system. This method is based on destructive sampling of a soil lysimeter designed to simulate a small-scale hillslope. A weighing lysimeter of one cubic meter capacity was divided into sections (voxels) and was excavated layer-by-layer, with sub samples being collected from each voxel. The excavation procedure was aimed at detecting the incipient heterogeneity of the system by focusing on the spatial assessment of hydrological, geochemical, and microbiological properties of the soil. Representative results of a few physicochemical variables tested show the development of heterogeneity. Additional work to test interactions between hydrological, geochemical, and microbiological signatures is planned to interpret the observed patterns. Our study also demonstrates the possibility of carrying out similar excavations in order to observe and quantify different aspects of soil-development under varying environmental conditions and scale.

This study presents an excavation method for investigating subsurface hydrological, geochemical, and microbiological heterogeneity of a soil lysimeter. The lysimeter simulates an artificial hillslope which was initially under homogeneous condition and had been subjected to approximately 5,000 mm of water over eight cycles of irrigation in an 18-month period.

土壤蒸渗仪开挖加之水文，地球化学和微生物调查

Studying co-evolution of hydrological and biogeochemical processes in the subsurface of natural landscapes can enhance the understanding of coupled ...

Reservoir Condition Pore-scale Imaging of Multiple Fluid Phases Using X-ray Microtomography

X-ray microtomography was used to image, at a resolution of 6.6 &#181;m, the pore-scale arrangement of residual carbon dioxide ganglia in the pore-space of a carbonate rock at pressures and temperatures representative of typical formations used for CO2 storage. Chemical equilibrium between the CO2, brine and rock phases was maintained using a high pressure high temperature reactor, replicating conditions far away from the injection site. Fluid flow was controlled using high pressure high temperature syringe pumps. To maintain representative in-situ conditions within the micro-CT scanner a carbon fiber high pressure micro-CT coreholder was used. Diffusive CO2 exchange across the confining sleeve from the pore-space of the rock to the confining fluid was prevented by surrounding the core with a triple wrap of aluminum foil. Reconstructed brine contrast was modeled using a polychromatic x-ray source, and brine composition was chosen to maximize the three phase contrast between the two fluids and the rock. Flexible flow lines were used to reduce forces on the sample during image acquisition, potentially causing unwanted sample motion, a major shortcoming in previous techniques. An internal thermocouple, placed directly adjacent to the rock core, coupled with an external flexible heating wrap and a PID controller was used to maintain a constant temperature within the flow cell. Substantial amounts of CO2 were trapped, with a residual saturation of 0.203 &#177; 0.013, and the sizes of larger volume ganglia obey power law distributions, consistent with percolation theory.

We present a methodology for the imaging of multiple fluid phases at reservoir conditions by the use of x-ray microtomography. We show some representative results of capillary trapping in a carbonate rock sample.

多重流体相储层孔隙条件级成像使用X射线微断层

X-ray microtomography was used to image, at a resolution of 6.6 &#181;m, the pore-scale arrangement of residual carbon dioxide ganglia in the pore-space ...

工程学

Resurrection of Dormant Daphnia magna: Protocol and Applications

Long-term studies enable the identification of eco-evolutionary processes that occur over extended time periods. In addition, they provide key empirical data that may be used in predictive modelling to forecast evolutionary responses of natural ecosystems to future environmental changes. However, excluding a few exceptional cases, long-term studies are scarce because of logistic difficulties associated with accessing temporal samples. Temporal dynamics are frequently studied in the laboratory or in controlled mesocosm experiments with exceptional studies that reconstruct the evolution of natural populations in the wild.
Here, a standard operating procedure (SOP) is provided to revive or resurrect dormant Daphnia magna, a widespread zooplankton keystone species in aquatic ecosystems, to dramatically advance the state-of-the-art longitudinal data collection in natural systems. The field of Resurrection Ecology was defined in 1999 by Kerfoot and co-workers, even though the first attempts at hatching diapausing zooplankton eggs date back to the late 1980s. Since Kerfoot&#39;s seminal paper, the methodology of resurrecting zooplankton species has been increasingly frequently applied, though propagated among laboratories only via direct knowledge transfer. Here, an SOP is described that provides a step-by-step protocol on the practice of resurrecting dormant Daphnia magna eggs.
Two key studies are provided in which the fitness response of resurrected Daphnia magna populations to warming is measured, capitalizing on the ability to study historical and modern populations in the same settings. Finally, the application of next generation sequencing technologies to revived or still dormant stages is discussed. These technologies provide unprecedented power in dissecting the processes and mechanisms of evolution if applied to populations that have experienced changes in selection pressure over time.

Resurrection of Dormant Daphnia magna: Protocol and Applications

Long-term studies are essential to understanding the process of evolution and the mechanisms of adaptation. Generally, these studies require commitments beyond the life-time of researchers. Here, a powerful method is described that dramatically advances state-of-the-art data collection to generate longitudinal data in natural systems.

休眠蚤的复活: 协议和应用

Long-term studies enable the identification of eco-evolutionary processes that occur over extended time periods. In addition, they provide key empirical ...

Sediment Core Extrusion Method at Millimeter Resolution Using a Calibrated, Threaded-rod

Aquatic sediment core subsampling is commonly performed at cm or half-cm resolution. Depending on the sedimentation rate and depositional environment, this resolution provides records at the annual to decadal scale, at best. An extrusion method, using a calibrated, threaded-rod is presented here, which allows for millimeter-scale subsampling of aquatic sediment cores of varying diameters. Millimeter scale subsampling allows for sub-annual to monthly analysis of the sedimentary record, an order of magnitude higher than typical sampling schemes. The extruder consists of a 2 m aluminum frame and base, two core tube clamps, a threaded-rod, and a 1 m piston. The sediment core is placed above the piston and clamped to the frame. An acrylic sampling collar is affixed to the upper 5 cm of the core tube and provides a platform from which to extract sub-samples. The piston is rotated around the threaded-rod at calibrated intervals and gently pushes the sediment out the top of the core tube. The sediment is then isolated into the sampling collar and placed into an appropriate sampling vessel (e.g., jar or bag). This method also preserves the unconsolidated samples (i.e., high pore water content) at the surface, providing a consistent sampling volume. This mm scale extrusion method was applied to cores collected in the northern Gulf of Mexico following the Deepwater Horizon submarine oil release. Evidence suggests that it is necessary to sample at the mm scale to fully characterize events that occur on the monthly time-scale for continental slope sediments.

An extrusion method using a calibrated threaded-rod is presented, which allows for mm scale subsampling of aquatic sediment cores. Millimeter-scale sampling is necessary to fully characterize recent event stratigraphy in sediment records.

沉积物核心挤压法在毫米的分辨率用校准，螺纹杆

Aquatic sediment core subsampling is commonly performed at cm or half-cm resolution. Depending on the sedimentation rate and depositional environment, ...

化学

Estimating Sediment Denitrification Rates Using Cores and N2O Microsensors

Denitrification is the primary biogeochemical process removing reactive nitrogen from the biosphere. The quantitative evaluation of this process has become particularly relevant for assessing the anthropogenic-altered global nitrogen cycle and the emission of greenhouse gases (i.e., N2O). Several methods are available for measuring denitrification, but none of them are completely satisfactory. Problems with existing methods include their insufficient sensitivity, and the need to modify the substrate levels or alter the physical configuration of the process using disturbed samples.This work describes a method for estimating sediment denitrification rates that combines coring, acetylene inhibition, and microsensor measurements of the accumulated N2O. The main advantages of this method are a low disturbance of the sediment structure and the collection of a continuous record of N2O accumulation; these enable estimates of reliable denitrification rates with minimum values up to 0.4-1 &#181;mol N2O m-2 h-1. The ability to manipulate key factors is an additional advantage for obtaining experimental insights. The protocol describes procedures for collecting the cores, calibrating the sensors, performing the acetylene inhibition, measuring the N2O accumulation, and calculating the denitrification rate. The method is appropriate for estimating denitrification rates in any aquatic system with retrievable sediment cores. If the N2O concentration is above the detection limit of the sensor, the acetylene inhibition step can be omitted to estimate the N2O emission instead of denitrification. We show how to estimate both actual and potential denitrification rates by increasing nitrate availability as well as the temperature dependence of the process. We illustrate the procedure using mountain lake sediments and discuss the advantages and weaknesses of the technique compared to other methods. This method can be modified for particular purposes; for instance, it can be combined with 15N tracers to assess nitrification and denitrification or field in situ measurements of denitrification rates.

Estimating Sediment Denitrification Rates Using Cores and N2O Microsensors

This method estimates sediment denitrification rates in sediment cores using the acetylene inhibition technique and microsensor measurements of the accumulated N2O. The protocol describes procedures for collecting the cores, calibrating the sensors, performing the acetylene inhibition, measuring the N2O accumulation, and calculating the denitrification rate.

利用岩体和 n 2o 微传感器估计沉积物脱氮率

Denitrification is the primary biogeochemical process removing reactive nitrogen from the biosphere. The quantitative evaluation of this process has ...

Isolation of Quartz Grains for Optically Stimulated Luminescence (OSL) Dating of Quaternary Sediments for Paleoenvironmental Research

Optically stimulated luminescence (OSL) dating quantifies the time since mineral grains were deposited and shielded from additional light or heat exposure, which effectively resets the luminescence clock. The systematics of OSL dating is based on the dosimetric properties of common minerals, like quartz and feldspar. The acquired luminescence with exposure to natural ionizing radiation after burial provides a depositional age for many Quaternary sedimentary systems, spanning the past 0.5 Ma. This contribution details the procedures for separating pure quartz grains of a known range of particle sizes to facilitate luminescence analysis with small or single grain aliquots. Specifically, protocols are given for the needed data and interpretations for effective OSL dating of terrestrial sediment cores or sample tubes from exposures. These cores, 5-20 m long in 1.2 m sections, are split lengthwise and crown-cut leaving 80% of core volume undisturbed, which facilitates sampling of light-protected sediment for OSL dating deep within the core. Sediment samples are then subjected to a series of physical separations to obtain a certain grain-size interval (e.g., 150-250 &#181;m). Magnetic minerals are removed in wet and dry states using magnets. A series of chemical digestions starts with soaking in H2O2 to remove organic matter, followed by HCl exposure to remove carbonate minerals, followed by density separation. Subsequently, grains are soaked in HF for 80 min and after in HCl to render solely quartz grains. The mineralogic purity (&#62;99%) of the quartz extract is quantified with grain petrographic assessment and Raman spectroscopy. Repeating this quartz isolation procedure may be necessary with sediment that contains &#60;15% quartz grains. Excitation of the purified quartz grains by LED-derived blue and IR light allows calculations of the fast and IR depletion ratios, which are metrics to assess the dominance of luminescence emissions from quartz.

Isolation of Quartz Grains for Optically Stimulated Luminescence OSL Dating of Quaternary Sediments for Paleoenvironmental Research

This protocol is for the isolation of quartz grains by size for luminescence dating of sediments. Outlined are physical cleansing and chemical digestions by soaking sequentially in H2O2, HCl, HF, and HCl again to isolate quartz grains. The quartz purity is quantified with microscopic assessment, Raman spectroscopy, and IR depletion ratio.

分离石英颗粒用于第四纪沉积物的光学刺激发光（OSL）测年，用于古环境研究

Optically stimulated luminescence (OSL) dating quantifies the time since mineral grains were deposited and shielded from additional light or heat ...

Pore-scale Imaging and Characterization of Hydrocarbon Reservoir Rock Wettability at Subsurface Conditions Using X-ray Microtomography

In situ wettability measurements in hydrocarbon reservoir rocks have only been possible recently. The purpose of this work is to present a protocol to characterize the complex wetting conditions of hydrocarbon reservoir rock using pore-scale three-dimensional X-ray imaging at subsurface conditions. In this work, heterogeneous carbonate reservoir rocks, extracted from a very large producing oil field, have been used to demonstrate the protocol. The rocks are saturated with brine and oil and aged over three weeks at subsurface conditions to replicate the wettability conditions that typically exist in hydrocarbon reservoirs (known as mixed-wettability). After the brine injection, high-resolution three-dimensional images (2 &#181;m/voxel) are acquired and then processed and segmented. To calculate the distribution of the contact angle, which defines the wettability, the following steps are performed. First, fluid-fluid and fluid-rock surfaces are meshed. The surfaces are smoothed to remove voxel artefacts, and in situ contact angles are measured at the three-phase contact line throughout the whole image. The main advantage of this method is its ability to characterize in situ wettability accounting for pore-scale rock properties, such as rock surface roughness, rock chemical composition, and pore size. The in situ wettability is determined rapidly at hundreds of thousands of points. 
The method is limited by the segmentation accuracy and X-ray image resolution. This protocol could be used to characterize the wettability of other complex rocks saturated with different fluids and at different conditions for a variety of applications. For example, it could help in determining the optimal wettability that could yield an extra oil recovery (i.e., designing brine salinity accordingly to obtain higher oil recovery) and to find the most efficient wetting conditions to trap more CO2 in subsurface formations.

This protocol is presented to characterize the complex wetting conditions of an opaque porous medium (hydrocarbon reservoir rock) using three-dimensional images obtained by X-ray microtomography at subsurface conditions.

利用 X 射线层析在地下条件下油气储层岩石润湿性的孔隙度成像与表征

In situ wettability measurements in hydrocarbon reservoir rocks have only been possible recently. The purpose of this work is to present a protocol to ...

Dissolved Solute Sampling Across an Oxic-Anoxic Soil-Water Interface Using Microdialysis Profilers

Biogeochemical processes shift rapidly in both spatial (millimeter scale) and temporal (hour scale to day scale) dimensions at the oxic-anoxic interface in response to disturbances. Deciphering the rapid biogeochemical changes requires in situ, minimally invasive tools with high spatial and temporal sampling resolution. However, the available passive sampling devices are not very useful in many cases either due to their disposable nature or the complexity and extensive workload for sample preparation.
To address this problem, a microdialysis profiler with 33 individual polyethersulfone nanomembrane tubes (semipermeable, &#60;20 nm pore size) integrated into the one-dimensional skeleton (60 mm) was established to iteratively sample the dissolved compounds in porewater across the soil-water interface at a high resolution of 1.8 mm (outer diameter plus one spacing, i.e., 0.1 mm between probes). The sampling mechanism is based on the principle of concentration gradient diffusion. The automatic loading of degassed water allows minimal disturbance to the chemical species across the oxic-anoxic interface.
This paper describes the procedures of device setup and continuous porewater sampling across the soil-water interface on a daily basis. Concentration-depth profiles were selectively measured before (on Day 6) and after (on Day 7) disturbances induced by irrigation. The results showed that concentration-depth profiles were undergoing rapid changes, especially for redox-sensitive elements (i.e., iron and arsenic). These protocols can help investigate the biogeochemical responses across the soil-water interface under various disturbances caused by physical, chemical, and biological factors. The paper thoroughly discusses the advantages and disadvantages of this method for potential use in the environmental sciences.

A microdialysis profiler is described to sample dissolved porewater solutes across an oxic-anoxic soil-water interface in situ with minimal disturbance. This device is designed to capture rapid changes in concentration-depth profiles induced by disturbances at the soil-water interface and beyond.

使用微透析剖面仪在氧化-缺氧土壤-水界面上进行溶解溶质采样

Biogeochemical processes shift rapidly in both spatial (millimeter scale) and temporal (hour scale to day scale) dimensions at the oxic-anoxic interface ...