Name: measurements of soil carbon by neutron-gamma analysis in static and scanning modes
Uploaded: 2017-08-24T14:00:00.000+00:00
Duration: 7 min 51 s
Description: Watch this Scientific Journal Video about Measurements of Soil Carbon by Neutron-Gamma Analysis in Static and Scanning Modes at JoVE.com

作者感谢巴里 g. 杜曼, 罗伯特 a. Icenogle, 胡安. 罗德里格斯, 莫里斯 g. 韦尔奇, 和马林 Siegford 在实验测量方面的技术援助, 以及对吉姆. 克拉克和德克斯特. 拉格朗的计算机模拟帮助。我们感谢夏 LLC 允许在这个项目中使用他们的电子和探测器。这项工作是支持 NIFA ALA 研究合同没有 ALA061-4-15014 "的土壤碳含量的精确地理空间测绘农业生产力和生命周期管理"。

1. 构建 ins 系统 <ol> <li> 使用在 图 1 中显示的常规 ins 系统几何. </li> </ol>
 <img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56270/56270fig1.jpg"/> 图 1 。 INS 系统几何 <a href="//ecsource.jove.com/files/ftp_upload/56270/56270fig1large.jpg" target="_blank"> 请单击此处查看此图的较大版本. </a> 
<ol start="2"> <li> 使用在 图 2 中显示的 INS 系统设计. 10 </li> </ol> <img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/56270/56270fig2.jpg"/> 图 2 。 INS 系统概述 
 A) 第一块包含中子发生器、中子探测器和电力系统; B) 第二块包含三奈 (Tl) 探测器; C) 第三个区块包含系统操作设备; D) 显示单个组件的第一个块的一般视图;和 E) 关闭伽玛探测器的视图。 10 <a href="//ecsource.jove.com/files/ftp_upload/56270/56270fig2large.jpg" target="_blank"> 请单击此处查看此图的较大版本. </a> 
<ol start="3"> <li> 在 INS 系统中使用三块 (见附录)。
	<ol> <li> 对于第一个块 (a), 使用中子发生器 (NG) 和电源系统 ( 图 2A 和 2D )。该发生器的脉冲中子输出将为 10 7 -10 8 n/秒, 中子能量为14兆伏特。电力系统将包括四电池 (12 伏, 105 Ah), 直流交流逆变器和充电器。该区块还将包含铁 (10 厘米 x 20 cm x 30 厘米) 和硼酸 (5 cm x 20 cm x 30 cm) 屏蔽, 以保护γ探测器免受中子辐照. 
		注: 中子探测器也包括在该区块中, 用于检查 NG 是否正常工作. </li>
		<li> 对于第二个块 (B), 使用伽玛射线测量设备 ( 图 2B 和 2E )。该区块将包含三 12.7 cm x 12.7 cm x 15.2 cm 闪烁奈 (Tl) 探测器与相应的电子学。探测器的外部尺寸与电子学将测量 15.2 cm x 15.2 cm x 46 cm. </li>
		<li> 对于第三个块 (C), 使用便携式计算机控制中子发生器 (使用 DNC 软件)、探测器和数据采集系统 ( 图 2C ). </li>
	</ol> </li> </ol> 2。警告和个人要求 <ol> <li> 让 INS 系统的每个用户都通过辐射训练. </li>
	<li> 确保操作 NG 的每个人都携带辐射监测徽章。在测量期间, 受限区域边界 (#62; 20 和 #181; Sv/h) 在 ng 附近将有辐射标志与词和 #34; 小心, 辐射区域. 和 #34; 禁区的所有边缘将不少于4米从 NG. </li>
	<li> 紧急情况下, 立即推 #34; 紧急中断和 #34; 在 ng 上的按钮, 从 ng 中删除该密钥, 然后从电源中拔下 ng. </li>
</ol> 3。测试 INS 系统的准备 <ol> <li> 检查电源系统。充电器上的电源电平指示器将是绿色的, 或者超过3盏红灯必须照亮。如果没有, 将充电器连接到电源插座, 等到电池完全充电 (绿灯亮亮), 或直到达到可接受的功率电平 (和 #8805; 3 盏红灯亮起). </li>
	<li> 打开逆变器 (绿灯灯照明) 和笔记本电脑. </li>
	<li> 运行便携式计算机上的数据采集程序以操作伽玛探测器, 并检查每个检测器所需的参数。这些参数的值将在 INS 系统测试之前定义和记录。
	<ol> <li> 将 Cs-137 控制源 (任何类型) 放在探测器的 5-15 cm 内. </li>
		<li> 启动光谱采集 1-3 分钟; 检查所有探测器的 662 Cs-137 峰值的质心。他们必须在同一个频道。如果不是, 使用数据获取程序的能量系数刻度, 通过改变值来调整662质心峰值. </li>
	</ol> </li> <li> 使用特殊键打开 NG。NG 上的指示灯将照亮绿色和黄色. </li>
</ol> 4。INS 系统的校准 <ol> <li> 准备4坑大小 1.5 m x 1.5 m x 0.6 m 与均匀的沙子-碳混合物 ( 图 3 )。碳含量为0、2.5、5和 10 w%. 
	注: 混凝土搅拌机用于建筑砂和椰子壳组成的合成土 (100% 碳含量, 平均粒径和 #60; 0.5 毫米)。这些混合物的均一性在视觉上被确定. </li>
</ol> <img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/56270/56270fig3.jpg"/> 图 3 。 坑用沙子和坑的看法与 10 Cw% 沙子-碳混合物 。<a href="//ecsource.jove.com/files/ftp_upload/56270/56270fig3large.jpg" target="_blank"> 请单击此处查看此图的较大版本. </a> 
<ol start="2"> <li> 使用以下步骤在凹坑上进行测量。
	<ol> <li> 手动将 INS 系统放置在坑上, 或用适当的车辆拖曳。定位 INS 系统, 使中子源的投射集中在坑上. </li>
		<li> 运行 NG 发生器的便携式计算机上的 DNC 软件。在 DNC 程序屏幕右侧的故障列中, 所有的灯都将照亮绿色;如果没有, 请单击 "清除" 按钮。插入以下参数: 对于脉冲参数-频率5赫, 占空比 25%, 延时0和 #181; s, 扩展2和 #181;对于梁-高电压 50 kV, 光束电流50和 #181; A (请注意, 根据特定的 INS 系统设置和任务, 这些参数可能会有所不同)。
		<ol> <li> 激活 DNC 程序屏幕上的开关, 等待 NG 进入工作状态, 在那里, 高压和光束电流将进入与输入值对应的稳定值;油藏电流也会趋于稳定值. </li>
		</ol> </li> <li> 运行便携式计算机上的数据采集软件以操作伽玛探测器。通过运行1小时的数据采集程序启动频谱采集。两种光谱采集过程 (INS 和 #38; 跨国公司和跨国公司) 将出现在屏幕上. </li>
		<li> 1 小时后, 停止频谱采集并将频谱保存到硬盘 (文件 |保存 MCA 数据 |选择文件夹并输入文件名. 
		注: 将有两个保存的频谱 (跨国公司和 INS) 与文件扩展名. mca 和 _gated 分别). </li>
		<li> 选择第二个探测器 (单击左上角的箭头) 并保存此探测器的频谱。对第三个探测器也这样做. </li>
		<li> 单击文件 |退出以关闭软件. </li>
		<li> 通过关闭 dnc 程序屏幕上的开关来关闭 dnc 软件. </li>
		<li> 对其他坑重复步骤 4.2.1 4.2.7. </li>
		<li> 使用特殊键关闭 NG。NG 上的指示灯会变暗. </li>
	</ol> </li> <li> 通过将整个 ins 系统提升到地面上方大于4米的距离并远离任何大型对象来确定 ins 系统的背景光谱, 并重复数据获取步骤 4.2.2-4.2.9. </li>
	<li> 数据处理 <ol> <li> 使用电子表格程序打开保存在步骤4.2.4 中的数据文件。分别查找28、27和30行中的输出和输入计数率 (OCR 和民事代表) 和实时 (RT) 的值. </li>
		<li> 计算 INS 和 #38 的生命时间 (LT); 跨国公司和跨国公司光谱为所有测量作为 LT 我 = OCR i /民事代表 i 和 #183; RT i (1), 在那里进行 OCR i 和民事代表 i 是 i/o 测量和 RT i 是真实的输出和输入计数率时间的测量. </li>
		<li> 通过将光谱 (电子表格中的33-2080 行) 除以对应的 LT 来计算每秒计数 (cps) 的伽玛谱. </li>
		<li> 计算每个坑的对应测量的净 INS 光谱为 
		净 ins 频谱 = (ins 和 #38; 跨国公司-跨国公司) 中继站 -(ins 和 #38; 跨国公司-跨国公司) Bkg (2) </li> <li> 在每个坑的网络 INS 频谱中查找伽玛峰1.78 兆伏特 ( 28 Si) 和4.44 兆伏特 ( 12 c), 并计算峰值区域 (4.44 兆电子伏特 c 峰值区域, 1.78 兆伏特 Si 峰顶区域) 使用伊戈尔软件。
		<ol> <li> 通过双击图标打开软件。在表中插入第一个净 INS 频谱. </li>
			<li> 单击窗口 |新图表 |从目标 |#34; 文件名和 #34; |做吧。频谱出现在图形窗口中。点击图 |显示信息。带有 a 和 B 标记的窗口显示在 "图形" 窗口下. </li>
			<li> 将鼠标指针放在符号 A 上, 按下鼠标左键, 并将光标拖动到1.78 兆伏特峰值的左侧的频谱上。将鼠标指针放在符号 B 上, 按下鼠标左键, 将光标拖动到1.78 兆伏特峰值的右侧频谱上. </li>
			<li> 单击分析 |多峰配合 |开始新的多峰值匹配 |从目标 |继续.在被标记的弹出窗口使用图表游标 |基线线性 |现在自动定位峰值 |做它 |峰值结果。峰值区域显示在弹出窗口中. </li>
			<li> 对4.44 兆伏特峰值重复相同的操作. </li>
			<li> 使用剩余的净 INS 频谱重复以前的所有操作. </li>
		</ol> </li> <li> 通过公式查找每个坑的净碳峰值区域 净 c 峰值区域 i = 4.44 兆伏特 c 峰值区域 i -0.058 和 #183; 1.78 兆伏特 Si 峰值区域 i (3) </li> <li> 建立 INS 系统的校准线作为直接支柱ortional 碳峰面积与碳浓度的关系, 以重量百分比表示。
		<ol> <li> 在伊戈尔软件中打开新表: 单击窗口 |新表。在第一列中输入坑碳浓度值, 第二列中的相应净 C 峰值区域. </li>
			<li> 绘制网 C 峰值区 vs 坑碳浓度: 单击窗口 |新图。选择净 C 峰面积为 YWave, 碳浓度为 XWave。单击 "执行"。这些点出现在图表上. </li>
			<li> 生成校准行: 单击分析 |曲线拟合 |功能线 |从目标 |做吧。校准线和校准系数 (k) 将出现在窗口中. </li>
		</ol> </li> </ol> </li> </ol> 5。在静态模式下进行野外土壤测量 <ol> <li> 根据步骤3准备用于测量的 INS 系统. </li>
	<li> 将系统放置在需要手动或使用合适的车辆拖曳土壤碳含量分析的站点上。定位 INS 系统, 使中子源的投射集中在被测量的站点上. </li>
	<li> 执行以下步骤 4.2.2-4.2.9 和 4.4.1-4.4.6 用于确定研究站点的净 C 峰值区域. </li>
	<li> 使用校准系数计算重量百分比中的碳浓度 
	<img alt="Equation 1" src="/files/ftp_upload/56270/56270eq1.jpg"/> </li> </ol> 6. 在扫描模式下进行野外土壤测量 <ol> <li> 评估 INS 系统将在该域中旅行的路径, 而计算旅行速度 (和 #8804; 5 公里/小时)、字段大小、INS 系统占地面积 (半径1米) 和测量时间 (1 h), 使移动轨迹最终覆盖整个领域。为方便起见, 将标志放置在沿外围区域的转弯处. </li>
	<li> 根据步骤3准备测试 INS 系统. </li>
	<li> 执行以下步骤的操作 4.2.2-4.2.3. </li>
	<li> 遵循预定的旅行路径1小时 </li>
	<li> 执行以下步骤 4.2.4-4.2.9 和 4.4.1-4.4.6 用于确定所研究字段的净 C 峰值区域. </li>
	<li> 使用校准系数按公式4计算重量的碳浓度%. </li>
</ol>

<ol>
	<li>Potter, K. N., Daniel, J. A., Altom, W., Torbert, H. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stocking+rate+effect+on+soil+carbon+and+nitrogen+in+degraded+soils.">Stocking rate effect on soil carbon and nitrogen in degraded soils.</a> J. Soil Water Conserv. 56, 233-236 (2001).</li><li>Torbert, H. A., Prior, S. A., Runion, G. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+the+return+to+cultivation+on+carbon+(C)+sequestration.">Impact of the return to cultivation on carbon (C) sequestration.</a> J. Soil Water Conserv. 59 (1), 1-8 (2004).</li><li>Stolbovoy, V., Montanarella, L., Filippi, N., Jones, A., Gallego, J., Grassi, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Soil sampling protocol to certify the changes of organic carbon stock in mineral soil of the European Union. Version 2. , (2007).</li><li>Smith, K. E., Watts, D. B., Way, T. R., Torbert, H. A., Prior, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+tillage+and+fertilizer+application+method+on+gas+emissions+(CO2,+CH4,+N2O)+in+a+corn+cropping+system.">Impact of tillage and fertilizer application method on gas emissions (CO2, CH4, N2O) in a corn cropping system.</a> Pedosphere. 22 (5), 604-615 (2012).</li><li>Seybold, C. A., Mausbach, M. J., Karlen, D. L., Rogers, H. H., Lal, R., Kimble, J., Stewart, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+soil+quality.">Quantification of soil quality.</a> Soil processes and the carbon cycle. , 387-404 (1997).</li><li>Nelson, D. W., Sommers, L. E., Sparks, 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=Total+carbon,+organic+carbon,+and+organic+matter.">Total carbon, organic carbon, and organic matter.</a> Methods of Soil Analysis., Part 3, Chemical Methods. , 961-1010 (1996).</li><li>Wielopolski, L., Carayannis, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nuclear+methodology+for+non-destructive+multi-elemental+analysis+of+large+volumes+of+soil.">Nuclear methodology for non-destructive multi-elemental analysis of large volumes of soil.</a> Planet Earth: Global Warming Challenges and Opportunities for Policy and Practice. , (2011).</li><li>Wielopolski, L., Yanai, R. D., Levine , C. R., Mitra, S., Vadeboncoeur, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid,+non-destructive+carbon+analysis+of+forest+soils+using+neutron-induced+gamma-ray+spectroscopy.">Rapid, non-destructive carbon analysis of forest soils using neutron-induced gamma-ray spectroscopy.</a> Forest Ecol. Manag. 260, 1132-1137 (2010).</li><li>Mitra, S., Wielopolski, L., Tan, H., Fallu-Labruyere, A., Hennig, W., Warburton, W. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Concurrent+measurement+of+individual+gamma-ray+spectra+during+and+between+fast+neutron+pulses.">Concurrent measurement of individual gamma-ray spectra during and between fast neutron pulses.</a> Nucl. Sci. 54 (1), 192-196 (2007).</li><li>Yakubova, G., Wielopolski, L., Kavetskiy, A., Torbert, H. A., Prior, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Field+testing+a+mobile+inelastic+neutron+scattering+system+to+measure+soil+carbon.">Field testing a mobile inelastic neutron scattering system to measure soil carbon.</a> Soil Sci. 179, 529-535 (2014).</li><li>Yakubova, G., Kavetskiy, A., Prior, S. A., Torbert, H. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Benchmarking+the+inelastic+neutron+scattering+soil+carbon+method.">Benchmarking the inelastic neutron scattering soil carbon method.</a> Vadose Zone J. 15 (2), (2016).</li><li>Knoll, G. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Radiation Detection and Measurement. , (2000).</li><li>Mitra, S., Dioszegi, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Unexploded+Ordnance+identification+-+A+gamma-ray+spectral+analysis+method+for+Carbon,+Nitrogen+and+Oxygen+signals+following+tagged+neutron+interrogation.">Unexploded Ordnance identification - A gamma-ray spectral analysis method for Carbon, Nitrogen and Oxygen signals following tagged neutron interrogation.</a> Nucl. Instrum. Meth. A. 693, 16-22 (2012).</li></ol>

作者没有什么可透露的。

在以前的研究人员建立的基础上, NSDL 工作人员讨论了在实际和成功地使用这项技术在现实世界领域中的关键问题。最初, NSDL 研究人员证明了在确定净碳峰值区时, 需要考虑 INS 系统的背景信号。11另一项努力表明, 净碳峰值面积是通过直接比例依赖性来表征上部 10 cm 土层 (不论碳深度分布形状) 的平均碳重量百分比。此外, 为 INS 系统校准所需的设备 (即, 1.5 m x 1.5 m x 0.6 m 坑?...

需要了解土壤碳含量, 以优化土壤生产力和利润率, 理解农用土地利用做法对土壤资源的影响, 并评估碳螯合的策略1, 2,3,4。土壤碳是土壤质量的普遍指标5。为土壤碳量测量开发了几种方法。干式燃烧 (DC) 是多年来使用最广泛的方法6;该方法是基于野外样品收集和实验室处理和测量, 具有破坏性, 劳动强度大, 耗时。两个新的方法是激光诱导击穿光谱学, 和近和中红外光谱学7。这些方法也是破坏性的并且只分析非常近表面土壤层数 (0.1-1 cm 土壤深度)。此外, 这些方法只对小样本量 (60 厘米3的 DC 方法) 和 0.01-10 cm3的红外光谱方法的碳含量进行点测量。这样的点测量使得很难将结果推断出场或横向尺度。因为这些方法是破坏性的, 所以重复的测量也是不可能的。
前文国家实验室的研究人员建议应用中子技术进行土壤碳分析 (INS 方法)7,8,9。这一初步的努力发展的理论和实践中使用中子伽马分析土壤碳测量。从2013年开始, 这项工作继续在美国农业部-ARS 国家土壤动力学实验室 (NSDL)。在过去10年中, 这种技术应用的扩大是由于两个主要因素: 相对便宜的商用中子发生器、伽玛探测器和相应的电子软件的可用性;和状态的艺术中子-原子核相互作用参考数据库。这种方法比其他方式有几个优点。一个 INS 系统, 放置在一个平台上, 可以操纵任何类型的领域, 需要测量。这种非破坏性的原位方法可以分析大的土壤体积 (约300千克), 可以通过少量的测量来对整个农业领域进行插值。这个 INS 系统也能够在扫描模式下运行, 它可以根据预先确定的域或横向网格的扫描来决定一个区域的平均碳含量。

<table><tbody><tr><td>Neutron Generator</td><td>Thermo Fisher Scientific, Colorado Springs, CO&lt;br/&gt; DNC software</td><td>MP320</td><td></td></tr><tr><td>Gamma-detector:</td><td></td><td>na</td><td></td></tr><tr><td>- NaI(Tl) crystal</td><td>Scionix USA, Orlando, FL</td><td></td><td></td></tr><tr><td>- Electronics</td><td>XIA LLC, Hayward, CA</td><td></td><td></td></tr><tr><td>- Software</td><td>ProSpect</td><td></td><td></td></tr><tr><td>Battery</td><td>Fullriver Battery USA, Camarillo, CA</td><td>DC105-12</td><td></td></tr><tr><td>Invertor</td><td>Nova Electric, Bergenfield, NJ</td><td>CGL 600W-series</td><td></td></tr><tr><td>Charger</td><td>PRO Charging Systems, LLC, LaVergne, TN</td><td>PS4</td><td></td></tr><tr><td>Block of Iron</td><td>Any</td><td>na</td><td></td></tr><tr><td>Boric Acid</td><td>Any</td><td>na</td><td></td></tr><tr><td>Laptop</td><td>Any</td><td>na</td><td></td></tr><tr><td>mu-metal</td><td>Magnetic Shield Corp., Bensenville, IL</td><td>&amp;nbsp;MU010-12</td><td></td></tr><tr><td>Construction sand</td><td>Any</td><td>na</td><td></td></tr><tr><td>Coconut shell</td><td>General Carbon Corp., Patterson, NJ</td><td>GC 8 X 30S</td><td></td></tr><tr><td>Reference Cs-137 source</td><td>Any</td><td>na</td><td></td></tr></tbody></table>

measurements of soil carbon by neutron-gamma analysis in static and scanning modes

本文介绍了非弹性中子散射 (INS) 法在土壤碳分析中的应用, 其基础是在中子与土壤元素相互作用时所产生的伽玛射线的登记和分析。ins 系统的主要部分是脉冲中子发生器, 奈 (Tl) 伽玛探测器, 分裂电子学, 以分离伽马谱由于 INS 和热中子捕获 (跨国公司) 的过程, 和软件的伽马谱采集和数据处理。这种方法比其他方法有几个优点, 因为它是一种非破坏性的原位方法, 用于测量大容量土壤中的平均碳含量, 地受土壤碳的局部剧烈变化的影响, 可用于静止或扫描模式。INS 方法的结果是, 在静止状态下, 从一个站点的碳含量为 2.5-3 m2 , 或者扫描体制中所遍历区域的平均碳含量。当前 INS 系统的测量范围是和 #62; 1.5 碳重量% (标准偏差± 0.3 w%) 在上部 10 cm 土壤层数为 1 hmeasurement。

土壤和 #38; 跨国公司和跨国公司的伽马谱
在图 4中显示了测量的土壤伽玛谱的一般视图。光谱由连续背景上的一组峰组成。主要的兴趣峰值质心在4.44 兆伏特和1.78 兆伏特在 INS 和 #38; 跨国公司光谱。第二峰可归因于土壤中的硅核, 第一峰是碳和硅核的重叠峰值。本文介绍了从这些光谱中提取净碳峰面积的方法。这一?...

Watch this Scientific Journal Video about Measurements of Soil Carbon by Neutron-Gamma Analysis in Static and Scanning Modes at JoVE.com

Measurements of Soil Carbon by Neutron-Gamma Analysis in Static and Scanning Modes

静态和扫描模式下中子伽马分析法测量土壤碳

在这里, 我们提出了使用中子伽玛技术进行单点测量 (静态模式) 或场平均值 (扫描模式) 的土壤碳的原位测量的协议。我们还描述系统建设和详细的数据处理程序。

The herein described application of the inelastic neutron scattering (INS) method for soil carbon analysis is based on the registration and analysis of ...

measurements-soil-carbon-neutron-gamma-analysis-static-scanning

Research

JoVE Journal

Engineering

7.3K 次观看.  Agricultural Research Service, United States Department of Agriculture. 在这里, 我们提出了使用中子伽玛技术进行单点测量 (静态模式) 或场平均值 (扫描模式) 的土壤碳的原位测量的协议。我们还描述系统建设和详细的数据处理程序。

视频: Measurements of Soil Carbon by Neutron-Gamma Analysis in Static and Scanning Modes

Design and Operation of a Continuous 13C and 15N Labeling Chamber for Uniform or Differential, Metabolic and Structural, Plant Isotope Labeling

Tracing rare stable isotopes from plant material through the ecosystem provides the most sensitive information about ecosystem processes; from CO2 fluxes and soil organic matter formation to small-scale stable-isotope biomarker probing. Coupling multiple stable isotopes such as 13C with 15N, 18O or&#160;2H has the potential to reveal even more information about complex stoichiometric relationships during biogeochemical transformations. Isotope labeled plant material has been used in various studies of litter decomposition and soil organic matter formation1-4. From these and other studies, however, it has become apparent that structural components of plant material behave differently than metabolic components (i.e. leachable low molecular weight compounds) in terms of microbial utilization and long-term carbon storage5-7. The ability to study structural and metabolic components separately provides a powerful new tool for advancing the forefront of ecosystem biogeochemical studies. Here we describe a method for producing 13C and 15N labeled plant material that is either uniformly labeled throughout the plant or differentially labeled in structural and metabolic plant components.
Here, we present the construction and operation of a continuous 13C and 15N labeling chamber that can be modified to meet various research needs. Uniformly labeled plant material is produced by continuous labeling from seedling to harvest, while differential labeling is achieved by removing the growing plants from the chamber weeks prior to harvest. Representative results from growing Andropogon gerardii Kaw demonstrate the system&#39;s ability to efficiently label plant material at the targeted levels. Through this method we have produced plant material with a 4.4 atom%13C and 6.7 atom%15N uniform plant label, or material that is differentially labeled by up to 1.29 atom%13C and 0.56 atom%15N in its metabolic and structural components (hot water extractable and hot water residual components, respectively). Challenges lie in maintaining proper temperature, humidity, CO2 concentration,&#160;and light levels in an airtight 13C-CO2 atmosphere for successful plant production. This chamber description represents a useful research tool to effectively produce uniformly or differentially multi-isotope labeled plant material for use in experiments on ecosystem biogeochemical cycling.

Design and Operation of a Continuous 13C and 15N Labeling Chamber for Uniform or Differential, Metabolic and Structural, Plant Isotope Labeling

This method explains how to build and operate a continuous 13C and 15N isotope labeling chamber for uniform or differential plant tissue labeling. Representative results from metabolic and structural labeling of Andropogon gerardii are discussed.

设计一个连续和操作<sup&gt; 13</sup&gt; C和<sup&gt; 15</sup&gt;Ñ贴标商会统一或差分，代谢和结构，植物同位素标记

Tracing rare stable isotopes from plant material through the ecosystem provides the most sensitive information about ecosystem processes; from CO2 fluxes ...

科研

环境科学

Measurement of Greenhouse Gas Flux from Agricultural Soils Using Static Chambers

Measurement of greenhouse gas (GHG) fluxes between the soil and the atmosphere, in both managed and unmanaged ecosystems, is critical to understanding the biogeochemical drivers of climate change and to the development and evaluation of GHG mitigation strategies based on modulation of landscape management practices. The static chamber-based method described here is based on trapping gases emitted from the soil surface within a chamber and collecting samples from the chamber headspace at regular intervals for analysis by gas chromatography. Change in gas concentration over time is used to calculate flux. This method can be utilized to measure landscape-based flux of carbon dioxide, nitrous oxide, and methane, and to estimate differences between treatments or explore system dynamics over seasons or years. Infrastructure requirements are modest, but a comprehensive experimental design is essential. This method is easily deployed in the field, conforms to established guidelines, and produces data suitable to large-scale GHG emissions studies.

This article showcases the static chamber-based method for measurement of greenhouse gas flux from soil systems. With relatively modest infrastructure investments, measurements may be obtained from multiple treatments/locations and over timeframes ranging from hours to years.

从农业土壤使用静态钱伯斯温室气体流量测量

Measurement of greenhouse gas (GHG) fluxes between the soil and the atmosphere, in both managed and unmanaged ecosystems, is critical to understanding the ...

Measuring Carbon-based Contaminant Mineralization Using Combined CO2 Flux and Radiocarbon Analyses

A method is described which uses the absence of radiocarbon in industrial chemicals and fuels made from petroleum feedstocks which frequently contaminate the environment. This radiocarbon signal &#8212; or rather the absence of signal &#8212; is evenly distributed throughout a contaminant source pool (unlike an added tracer) and is not impacted by biological, chemical or physical processes (e.g., the 14C radioactive decay rate is immutable). If the fossil-derived contaminant is fully degraded to CO2, a harmless end-product, that CO2 will contain no radiocarbon. CO2 derived from natural organic matter (NOM) degradation will reflect the NOM radiocarbon content (usually &#60;30,000 years old). Given a known radiocarbon content for NOM (a site background), a two end-member mixing model can be used to determine the CO2 derived from a fossil source in a given soil gas or groundwater sample. Coupling the percent CO2 derived from the contaminant with the CO2 respiration rate provides an estimate for the total amount of contaminant degraded per unit time. Finally, determining a zone of influence (ZOI) representing the volume from which site CO2 is collected allows determining the contaminant degradation per unit time and volume. Along with estimates for total contaminant mass, this can ultimately be used to calculate time-to-remediate or otherwise used by site managers for decision-making.

Measuring Carbon-based Contaminant Mineralization Using Combined CO2 Flux and Radiocarbon Analyses

A protocol is described wherein CO2 mineralized from organic contaminant (derived from petroleum feedstocks) biodegradation is trapped, quantified, and analyzed for 14C content. A model is developed to determine CO2 capture zone's spatial extent. Spatial and temporal measurements allow integrating contaminant mineralization rates for predicting remediation extent and time.

测量碳为基础的污染物矿化结合使用CO<sub&gt; 2</sub&gt;助焊剂和放射性碳分析

A method is described which uses the absence of radiocarbon in industrial chemicals and fuels made from petroleum feedstocks which frequently contaminate ...

Assessment of Labile Organic Carbon in Soil Using Sequential Fumigation Incubation Procedures

Management practices and environmental changes can alter soil nutrient and carbon cycling. Soil labile organic carbon, a readily decomposable C pool, is highly sensitive to disturbance. It is also the primary substrate for soil microorganisms, which is fundamental to nutrient cycling. Due to these attributes, labile organic carbon (LOC) has been identified as an indicator parameter for soil health. Quantifying the turnover rate of LOC also aids in understanding changes in soil nutrient cycling processes. A sequential fumigation incubation method has been developed to estimate soil LOC and potential C turnover rate. The method requires fumigating soil samples and quantifying CO2-C respired during a 10 day incubation period over a series of fumigation-incubation cycles. Labile organic C and potential C turnover rate are then extrapolated from accumulated CO2 with a negative exponential model. Procedures for conducting this method are described.

Labile organic carbon (LOC) and the potential carbon turnover rate are sensitive indicators of changes in soil nutrient cycling processes. Details are provided for a method based on fumigating and incubating soil in a series of cycles and using the CO2 accumulated during the incubation periods to estimate these parameters.

活性有机碳评估土壤中连续熏蒸孵化程序

Management practices and environmental changes can alter soil nutrient and carbon cycling. Soil labile organic carbon, a readily decomposable C pool, is ...

Measuring and Mapping Patterns of Soil Erosion and Deposition Related to Soil Carbonate Concentrations Under Agricultural Management

Spatial patterns of soil erosion and deposition can be inferred from differences in ground elevation mapped at appropriate time increments. Such changes in elevation are related to changes in near-surface soil carbonate (CaCO3) profiles. The objective is to describe a simple conceptual model and detailed protocol for repeatable field and laboratory measurements of these quantities. Here, accurate elevation is measured using a ground-based differential global positioning system (GPS); other data acquisition methods could be applied to the same basic method. Soil samples are collected from prescribed depth intervals and analyzed in the lab using an efficient and precise modified pressure-calcimeter method for quantitative analysis of inorganic carbon concentration. Standard statistical methods are applied to point data, and representative results show significant correlations between changes in soil surface layer CaCO3 and changes in elevation consistent with the conceptual model; CaCO3 generally decreased in depositional areas and increased in erosional areas. Maps are derived from point measurements of elevation and soil CaCO3 to aid analyses. A map of erosional and depositional patterns at the study site, a rain-fed winter wheat field cropped in alternating wheat-fallow strips, shows the interacting effects of water and wind erosion affected by management and topography. Alternative sampling methods and depth intervals are discussed and recommended for future work relating soil erosion and deposition to soil CaCO3.

Spatial patterns of soil erosion and deposition can be inferred from differences in ground elevation mapped at appropriate time increments. Such changes in elevation are related to changes in near-surface soil carbonates. Repeatable methods for field and laboratory measurements of these quantities and data analysis methods are described here.

农业经营条件下土壤侵蚀和沉积与土壤碳酸盐浓度关系的测量与制图

Spatial patterns of soil erosion and deposition can be inferred from differences in ground elevation mapped at appropriate time increments. Such changes ...

Quantification of Hydrogen Concentrations in Surface and Interface Layers and Bulk Materials through Depth Profiling with Nuclear Reaction Analysis

Nuclear reaction analysis (NRA) via the resonant 1H(15N,&#945;&#947;)12C reaction is a highly effective method of depth profiling that quantitatively and non-destructively reveals the hydrogen density distribution at surfaces, at interfaces, and in the volume of solid materials with high depth resolution. The technique applies a 15N ion beam of 6.385 MeV provided by an electrostatic accelerator and specifically detects the 1H isotope in depths up to about 2 &#956;m from the target surface. Surface H coverages are measured with a sensitivity in the order of ~1013 cm-2 (~1% of a typical atomic monolayer density) and H volume concentrations with a detection limit of ~1018 cm-3 (~100 at. ppm). The near-surface depth resolution is 2-5 nm for surface-normal 15N ion incidence onto the target and can be enhanced to values below 1 nm for very flat targets by adopting a surface-grazing incidence geometry. The method is versatile and readily applied to any high vacuum compatible homogeneous material with a smooth surface (no pores). Electrically conductive targets usually tolerate the ion beam irradiation with negligible degradation. Hydrogen quantitation and correct depth analysis require knowledge of the elementary composition (besides hydrogen) and mass density of the target material. Especially in combination with ultra-high vacuum methods for in-situ target preparation and characterization, 1H(15N,&#945;&#947;)12C NRA is ideally suited for hydrogen analysis at atomically controlled surfaces and nanostructured interfaces. We exemplarily demonstrate here the application of 15N NRA at the MALT Tandem accelerator facility of the University of Tokyo to (1) quantitatively measure the surface coverage and the bulk concentration of hydrogen in the near-surface region of a H2 exposed Pd(110) single crystal, and (2) to determine the depth location and layer density of hydrogen near the interfaces of thin SiO2 films on Si(100).

We illustrate the application of 1H(15N,&#945;&#947;)12C resonant nuclear reaction analysis (NRA) to quantitatively evaluate the density of hydrogen atoms on the surface, in the volume, and at an interfacial layer of solid materials. The near-surface hydrogen depth profiling of a Pd(110) single crystal and of SiO2/Si(100) stacks is described.

通过与核反应分析深度剖面的表面和界面层和颗粒材料氢含量的定量

Nuclear reaction analysis (NRA) via the resonant 1H(15N,&#945;&#947;)12C reaction is a highly effective method of depth profiling that quantitatively and ...

工程学

Two-Dimensional Visualization and Quantification of Labile, Inorganic Plant Nutrients and Contaminants in Soil

We describe a method for two-dimensional (2D) visualization and quantification of the distribution of labile (i.e., reversibly adsorbed) inorganic nutrient (e.g., P, Fe, Mn) and contaminant (e.g., As, Cd, Pb) solute species in the soil adjacent to plant roots (the &#8216;rhizosphere&#8217;) at sub-millimeter (~100 &#181;m) spatial resolution. The method combines sink-based solute sampling by the diffusive gradients in thin films (DGT) technique with spatially resolved chemical analysis by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The DGT technique is based on thin hydrogels with homogeneously distributed analyte-selective binding phases. The variety of available binding phases allows for the preparation of different DGT gel types following simple gel fabrication procedures. For DGT gel deployment in the rhizosphere, plants are grown in flat, transparent growth containers (rhizotrons), which enable minimal invasive access to a soil-grown root system. After a pre-growth period, DGT gels are applied to selected regions of interest for in situ solute sampling in the rhizosphere. Afterwards, DGT gels are retrieved and prepared for subsequent chemical analysis of the bound solutes using LA-ICP-MS line-scan imaging. Application of internal normalization using 13C and external calibration using matrix-matched gel standards further allows for the quantification of the 2D solute fluxes. This method is unique in its capability to generate quantitative, sub-mm scale 2D images of multi-element solute fluxes in soil-plant environments, exceeding the achievable spatial resolution of other methods for measuring solute gradients in the rhizosphere substantially. We present the application and evaluation of the method for imaging multiple cationic and anionic solute species in the rhizosphere of terrestrial plants and highlight the possibility of combining this method with complementary solute imaging techniques.

This protocol presents a workflow for sub-mm 2D visualization of multiple labile inorganic nutrient and contaminant solute species using diffusive gradients in thin films (DGT) combined with mass spectrometry imaging. Solute sampling and high-resolution chemical analysis are described in detail for quantitative mapping of solutes in the rhizosphere of terrestrial plants.

土壤中实验室、无机植物养分和污染物的二维可视化和量化

We describe a method for two-dimensional (2D) visualization and quantification of the distribution of labile (i.e., reversibly adsorbed) inorganic ...

Monitoring Pedogenic Inorganic Carbon Accumulation Due to Weathering of Amended Silicate Minerals in Agricultural Soils.

The present study aims to demonstrate a systematic procedure for monitoring inorganic carbon induced by enhanced weathering of comminuted rocks in agricultural soils. To this end, the core soil samples taken at different depth (including 0-15 cm, 15-30 cm, and 30-60 cm profiles) are collected from an agriculture field, the topsoil of which has already been enriched with an alkaline earth metal silicate containing mineral (such as wollastonite). After transporting to the laboratory, the soil samples are air-dried and sieved. Then, the inorganic carbon content of the samples is determined by a volumetric method called calcimetry. The representative results presented herein showed five folded increments of inorganic carbon content in the soils amended with the Ca-silicate compared to control soils. This compositional change was accompanied by more than 1 unit of pH increase in the amended soils, implying high dissolution of the silicate. Mineralogical and morphological analyses, as well as elemental composition, further corroborate the increase in the inorganic carbon content of silicate-amended soils. The sampling and analysis methods presented in this study can be adopted by researchers and professionals looking to trace pedogenic inorganic carbon changes in soils and subsoils, including those amended with other suitable silicate rocks such as basalt and olivine. These methods can also be exploited as tools for verifying soil inorganic carbon sequestration by private and governmental entities to certify and award carbon credits.

The verification method described here is adaptable for monitoring pedogenic inorganic carbon sequestration in various agricultural soils amended with alkaline earth metal silicate-containing rocks, such as wollastonite, basalt, and olivine. This type of validation is essential for carbon credit programs, which can benefit farmers that sequester carbon in their fields.

监测农业土壤中经修正的硅酸盐矿物风化造成的致病性无机碳积累。

The present study aims to demonstrate a systematic procedure for monitoring inorganic carbon induced by enhanced weathering of comminuted rocks in ...

Utilizing Soil Density Fractionation to Separate Distinct Soil Carbon Pools

Soil organic matter (SOM) is a complicated mixture of different compounds that span the range from free, partially degraded plant components to more microbially altered compounds held in the soil aggregates to highly processed microbial by-products with strong associations with reactive soil minerals. Soil scientists have struggled to find ways to separate soil into fractions that are easily measurable and useful for soil carbon (C) modeling. Fractionating soil based on density is increasingly being used, and it is easy to perform and yields C pools based on the degree of association between the SOM and different minerals; thus, soil density fractionation can help to characterize the SOM and identify SOM stabilization mechanisms. However, the reported soil density fractionation protocols vary significantly, making the results from different studies and ecosystems hard to compare. Here, we describe a robust density fractionation procedure that separates particulate and mineral-associated organic matter and explain the benefits and drawbacks of separating soil into two, three, or more density fractions. Such fractions often differ in their chemical and mineral composition, turnover time, and degree of microbial processing, as well as the degree of mineral stabilization.

Soil density fractionation separates soil organic matter into distinct pools with differing stabilization mechanisms, chemistries, and turnover times. Sodium polytungstate solutions with specific densities allow the separation of free particulate organic matter and mineral-associated organic matter, resulting in organic matter fractions suitable for describing the soil response to management and climate change.

利用土壤密度分馏分离不同的土壤碳库

Soil organic matter (SOM) is a complicated mixture of different compounds that span the range from free, partially degraded plant components to more ...

Neutron Radiography and Computed Tomography of Biological Systems at the Oak Ridge National Laboratory's High Flux Isotope Reactor

Neutrons have historically been used for a broad range of biological applications employing techniques such as small-angle neutron scattering, neutron spin echo, diffraction, and inelastic scattering. Unlike neutron scattering techniques that obtain information in reciprocal space, attenuation-based neutron imaging measures a signal in real space that is resolved on the order of tens of micrometers. The principle of neutron imaging follows the Beer-Lambert law and is based on the measurement of the bulk neutron attenuation through a sample. Greater attenuation is exhibited by some light elements (most notably, hydrogen), which are major components of biological samples. Contrast agents such as deuterium, gadolinium, or lithium compounds can be used to enhance contrast in a similar fashion as it is done in medical imaging, including techniques such as optical imaging, magnetic resonance imaging, X-ray, and positron emission tomography. For biological systems, neutron radiography and computed tomography have increasingly been used to investigate the complexity of the underground plant root network, its interaction with soils, and the dynamics of water flux in situ. Moreover, efforts to understand contrast details in animal samples, such as soft tissues and bones, have been explored. This manuscript focuses on the advances in neutron bioimaging such as sample preparation, instrumentation, data acquisition strategy, and data analysis using the High Flux Isotope Reactor CG-1D neutron imaging beamline. The aforementioned capabilities will be illustrated using a selection of examples in plant physiology&#160;(herbaceous plant/root/soil system)&#160;and biomedical applications&#160;(rat femur and mouse lung).

This manuscript describes a protocol for neutron radiography and computed tomography of biological samples using a High Flux Isotope Reactor (HFIR) CG-1D beamline to measure a metal implant in a rat femur, a mouse lung, and an herbaceous plant root/soil system.

橡树岭国家实验室高通量同位素反应堆的中子射线照相和生物系统计算机断层扫描

Neutrons have historically been used for a broad range of biological applications employing techniques such as small-angle neutron scattering, neutron ...

静态和扫描模式下中子伽马分析法测量土壤碳

摘要

探索更多视频

此视频中的章节

设计一个连续和操作