Optimization of Extraction Method for Easily Extractable Glomalin-Related Soil Protein from Calcareous Soil
-
摘要:
在水-二氧化碳-碳酸盐岩-生物的相互作用下，全球形成8.24×108t C/a的岩溶碳汇，其中部分岩溶碳汇以土壤有机质的形式固存，进而在国家双碳目标中发挥重要作用。全球分布广泛的丛枝菌根真菌分泌的球囊霉素相关土壤蛋白(Glomalin-related soil protein，GRSP)性质稳定、不易分解，是土壤有机质的重要组成部分。提取合格的GRSP是深入研究岩溶土壤有机碳汇的基础，然而以往研究因GRSP提取量不高、提取不充分、产物不专一等问题，以至其在有机质中发挥的作用机制无法深入开展研究，因此，提高GRSP提取量对于探究岩溶土壤有机质的形成和稳定机制具有重要意义。本文选取岩溶区黑色、棕色、黄色和红色四种石灰土，通过温度和时间正交实验，筛选出适用于岩溶土壤颗粒态有机质(POM)和矿物结合态有机质(MAOM)易提取球囊霉素相关土壤蛋白(EE-GRSP)的最佳提取条件。实验结果表明，POM和MAOM在123℃和80min条件下提取时，EE-GRSP提取量最高。应用于四类石灰土后，EE-GRSP增量范围为4.6%～34.2%。相较于全土，MAOM具有更高的稳定性与更强的有机碳保护能力。因此，随着温度和提取时间的提高，MAOM中的EE-GRSP得到更完全的释放，提取量显著提高。由此可见，EE-GRSP提取条件优化对深入研究岩溶土壤碳汇潜力及其稳定机制具有重要意义。
-
关键词:
- 易提取球囊霉素相关土壤蛋白 /
- 提取条件优化 /
- 颗粒态有机质 /
- 矿物结合态有机质
要点(1)提高温度、延长提取时间可提高石灰土易提取球囊霉素相关土壤蛋白提取量。
(2)通过正交实验进行提取条件探索，并将优化条件应用于石灰土实际样品，实验假设得到验证。
(3)石灰土颗粒态有机质和矿物结合态有机质的易提取球囊霉素相关土壤蛋白提取条件区别于全土，需要提高提取温度、延长提取时间。
HIGHLIGHTS(1) The amount of easily extractable glomalin-related soil protein from calcareous soil will be increased by increasing extraction temperature and prolonging extraction time.
(2) An optimization condition was selected and applied to four types of calcareous soil based on orthogonal experiments, which verifies the experimental hypothesis.
(3) The extraction condition about easily extractable glomalin-related soil protein from particulate organic matter and mineral-associated organic matter is different from bulk soil, so it is necessary to increase extracting temperature and prolong extracting time.
Abstract:Glomalin-related soil protein (GRSP) secreted by arbuscular mycorrhizal fungi is widely distributed worldwide, has stable properties and is not easily decomposed, which is an important component of soil organic matter. Extracting high quality GRSP is important for in-depth research on organic carbon sinks in calcareous soil from karst areas. However, in previous studies, the mechanism of GRSP in organic matter could not be further studied due to low extraction yield, insufficient extraction and non-specific products. Therefore, the high extraction amount of GRSP is of great significance to explore the formation and stabilization mechanism of organic matter in calcareous soil. This experiment selected four types of calcareous soil from karst areas: black, brown, yellow and red calcareous soil. By using orthogonal experiments of temperature and time, the optimal extraction conditions for easily extractable glomalin-related soil protein (EE-GRSP) related to particulate organic matter (POM) and mineral-associated organic matter (MAOM) in calcareous soil were selected. The experimental results showed that the highest extraction amount of EE-GRSP was achieved when POM and MAOM were extracted at 123℃ and 80min. After application into the four types of calcareous soil, the EE-GRSP contents increased from 4.6% to 34.2%. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202402060015.
BRIEF REPORTSignificance: Under the interaction of water-carbon dioxide-carbonate rocks-organisms, a global karst carbon sink of 8.24×108t C/a is formed. Some of the carbon sinks were sequestered in the form as soil organic matter, which plays an important role in the dual carbon goals. Glomalin-related soil protein, as a part of soil organic carbon, is stable and difficult to decompose, and plays an important role in soil carbon sequestration[6]. The extraction process of GRSP remains inadequate. Many scholars have improved the extraction time and centrifugal force, but few of them have optimized the extraction temperature and time by orthogonal optimization. After a single adjustment of the extraction condition, EE-GRSP from soils was mostly concentrated in 0.5−1.0mg/g[46-47]. In this study, temperature, time experiment and two-factor orthogonal experiments were carried out sequentially. After an optimized condition was selected, four types of calcareous soil from the karst area were used to verify the experimental hypothesis. By using this optimization extracting method, EE-GRSP content from calcareous soil can reach up to 1.375mg/g.
Methods: Black, brown, yellow, and red calcareous soil were collected in Nonggang Nature Reserve in Guangxi, China. Bulk samples were mixed well by removing debris such as gravel and stubs. Bulk soil was air-dried and sieved through a 10-mesh sieve. POM and MAOM were obtained by applying the wet sieving method. The 0.5g samples were placed in a 15mL centrifuge tube and parallel samples were set up. According to the ratio of sample and extraction solution (1∶8), 20mmol/L sodium citrate solution (pH=7) was added into the centrifuge tube. Samples were put into an autoclave with the lid open and extracted for 80min at 123℃, and then centrifuged at 9500r/min for 10min after sterilization. The supernatant was retained at 4℃ for the determination of EE-GRSP content.
Data and Results: (1) The main factors affecting EE-GRSP extraction. Sterilization samples were used with open or closed lids. After the lid was closed, EE-GRSP content decreased from 0.591mg/g to 0.105mg/g in brown calcareous soil and in red calcareous soil from 0.071mg/g to 0.011mg/g, as shown in Fig.1. With the extension of extraction time, EE-GRSP content increased in the brown calcareous soil and red calcareous soil sample, as listed in Fig.2.
(2) Results of time and temperature orthogonal optimization experiment. By comparing the extracted amount of EE-GRSP, POM peaked at 123℃ and 80min, which was significantly higher than the other extraction conditions (p<0.05), as seen in Table 1.
(3) Extraction results of actual samples. After increasing the extraction temperature and time, EE-GRSP content of the black calcareous soil-particulate organic matter increased from 0.833 to 1.118mg/g. The previous studies indicated that the extraction amount of EE-GRSP from non-karst area soil was 0.5−0.6mg/g[46], and the EE-GRSP content of brown calcareous soil was 0.4−1.17mg/g[47]. In this study, the EE-GRSP contents of POM and MAOM in black, brown and yellow calcareous soil were significantly increased about 11.5%−30.4% by using this optimization extraction method, as shown in Fig.3. Compared to bulk soil, MAOM had higher stability and stronger organic carbon protection ability. Therefore, by using increased temperature and extraction time, the EE-GRSP content in MAOM is completely released, and the extraction amount can be significantly increased.
-
微裂缝是页岩的重要孔隙类型[1-3]，可以形成良好的渗流网络从而改善储层质量[4-6]，对其进行定量研究有利于认识页岩储层类型与页岩气勘探潜力评价。对于宏观裂缝，国内外主要通过线、面等维度去描述裂缝的条数与密度等信息[7-9]，而页岩中微裂缝尺度较小，缝宽约在0.1mm以下，长约在50mm以下[10-12]，分析微裂缝对孔隙度的影响为进一步研究的难点。国外学者主要采用高分辨率的成像与测试技术对微裂缝进行定性观察评价[3, 13-14]，如Loucks等[14]通过大量的薄片与扫描电镜观察并记载了页岩中的天然微裂缝，探讨了微裂缝的重要性。我国学者尝试采用双孔隙介质模型法[15-16]、高压压汞[17-19]以及微米级X射线断层成像(微米CT)[20-24]等方法对微裂缝进行定量研究。双孔隙介质模型法通过建立物理模型定量计算页岩中的基质孔隙度与微裂缝孔隙度[16]，由于需要大量配套的岩石氦气孔隙度与矿物组成的资料，大大限制了其在资料较少井区的使用。高压压汞法可对页岩中的微裂缝进行研究，微裂缝在高压压汞曲线中表现为进汞速率较高的斜线段，将该段的孔容与渗透率值累积可分析微裂缝对总孔与渗透率的贡献[17]。由于高压压汞难以探测页岩的部分中-微孔隙，故其方法可能存在一定误差。
微米CT技术能够直观地展示微米级孔隙的三维状态，统计出其孔径分布以及孔隙度[25-31]，为页岩中微裂缝的精细刻画提供了良好的技术手段。屈乐等[25-26]详细描述了微米CT技术的建模方法，实现了对岩石孔隙结构与渗流特征等特性的表征，为该方法应用于页岩储层中提供了良好的借鉴。黄振凯等[27]介绍了微米CT技术在松辽盆地白垩系页岩中的应用，页岩孔隙类型以粒间孔隙和晶间孔隙为主，直径在0.7~25μm。苟启洋等[30-31]通过微米CT技术将页岩中识别出的微米级孔隙均归结为微裂缝，认为四川涪陵地区页岩的微裂缝的孔隙度达到1.24%[30]，而实际上应用该技术仍能识别出一部分微米级孔隙，故微裂缝孔隙度应该小于该值。根据已有的应用情况，微米CT技术是目前表征页岩中微裂缝最为直观有效的方法，但是在微裂缝的划分与孔隙度求取方面仍存在难题。
四川盆地北部元坝地区大安寨段低丰度总有机碳(TOC平均约1.12%)背景下多口井钻获了中高产工业气流[32-35]，前人研究认为页岩中微裂缝非常发育，发育构造微裂缝等多种微裂缝[35]。但是在实际勘探生产中，对于页岩储层类型的认识存在“孔隙型”与“裂缝型”的疑惑，定量评价微裂缝的发育程度影响着该区页岩气勘探开发潜力的评价。为了定量评价元坝地区大安寨段页岩中微裂缝的发育程度，本文通过微米CT实验，采用二维图像上微裂缝的识别与统计，通过积分的方法精确计算三维空间下的微裂缝孔隙度，同时结合氦气孔隙度对其总孔隙进行评价，分析了微裂缝占页岩总孔隙空间的比例，从页岩孔隙的角度对页岩气勘探开发潜力进行了探讨。
1. 实验部分
1.1 实验样品基本信息
实验样品主要为来自川北元坝地区大安寨段的黑色页岩，共5块，样品基本信息见表 1，部分样品为来自川东涪陵地区弧形高陡褶皱带大安寨段的黑色页岩(2块：FY1-9与FY1-13)。样品均为实际勘探中的柱状钻井岩心，采样深度2605.70~4140.75m。编号FY1-X前面FY1代表井号，后面X代表样品号，依此类推。页岩样品的TOC含量主要在0.47%~1.48%，平均1.12%，为本区典型的富有机质页岩[36-38]。页岩的无机矿物组成具有高黏土矿物与高脆性矿物含量的特点，黏土矿物含量36.50%~61.90%，平均48.49%，脆性矿物含量38.1%~63.5%，平均51.51%，主要为石英(平均27.76%)与方解石(平均14.90%)，并且含有少量长石、黄铁矿、菱铁矿、白云石等矿物[36-38]。
表 1 页岩样品基本信息Table 1. Basic information of shale samples研究地区 构造带 样品编号 采样深度(m) 层位 岩性 涪陵地区 川东弧形高陡 FY1-9 2605.70 大安寨段 黑色页岩 褶皱带 FY1-13 2636.00 大安寨段 黑色页岩 元坝地区 巴中低缓构造带 YB102-7 3923.19 大安寨段 黑色页岩 元坝东部断褶带 YL171-5 3885.28 大安寨段 黑色页岩 YL176-7 4140.75 大安寨段 黑色页岩 元坝中部断褶带 YL4-6 3748.38 大安寨段 黑色页岩 YL4-10 3752.18 大安寨段 黑色页岩 1.2 微米CT实验微裂缝孔隙度分析
微米CT实验在中国石油勘探开发研究院石油地质实验中心进行，使用仪器为Xradia Ultra-XRM L200立体显微镜，使用电压为8kV，仪器极限分辨率为0.7μm。样品为垂直页岩层理制样，形态为高约1cm直径约4mm的圆柱状。将样品竖直固定在设备中用X射线扫描，获取岩心的三维数据体。本文使用Avizo 9.0对三维数据体进行常规分析，根据不同密度与厚度的物体吸收X射线能力不同，可将页岩中的物质分为含铁矿物、矿物基质、孔隙和微裂缝三部分[25-28]：含铁矿物密度大，在图像中亮度最高，为亮白色；矿物基质主要为黏土矿物与碳酸盐岩矿物等，密度中等，在图像中呈现为灰白色；孔隙和微裂缝由于密度最小，常常呈现为灰黑色。根据图像灰度的差异通过阈值分割的方法将三者进行区分，可以建立页岩中微米级孔隙与微裂缝三维分布的模型[30-31]。
由于采用阈值分割方法无法将微裂缝与孔隙区分开，故通过人工识别与统计的方法计算微裂缝的孔隙度。将每个样品的三维数据体沿Z轴导出约1000张TIFF格式的二维灰度切片，在灰度切片上可以清楚地看出微裂缝的形态(图 1a、c)。每20张选出一张，选出等距离的50张图像。将图像导入CoreDRAW软件中，用发丝细的线条将微裂缝的边缘勾勒出来(图 1c)，利用一个Visual Basic编写的宏程序插件可以对该软件中封闭曲线的像素面积进行统计，通过公式(1)与公式(2)计算微裂缝孔隙度。三维孔隙度计算的模型如图 1b所示。
$ {F_n} = \frac{{{f_1} + {f_2} + \ldots + {f_i}}}{S} $
(1) $ {\phi _f} = \frac{{0.5 \times ({F_1} + {F_2}) \times h + \ldots + 0.5 \times ({F_{n - 1}} + {F_n}) \times h}}{{n \times h}} $
(2) ![]()
图 1 微米CT微裂缝孔隙度计算方法a—微米CT二维灰度图像；b—微裂缝孔隙度计算方法；c—微裂缝人工识别图像。Figure 1. Calculation method of micro-fracture porosity in micro-CT公式(1)为微裂缝的面孔率计算方法，公式(2)为样品的微裂缝孔隙度计算方法。式中：Fn为第n张切片的微裂缝面孔率，本文n等于50；S为圆形灰色视域的总像素面积；fi为第i条裂缝的像素值；ϕf为第f个样品的微裂缝孔隙度值，本文f等于7；h为任意两张切片之间的间距。
1.3 氦气法孔隙度测量
由于氦气法可以测量页岩的全尺度孔隙度，故用该方法评价页岩的总孔隙空间的发育情况[39-41]。该方法根据波义耳定律通过氦气膨胀测量柱体岩石骨架体积和孔隙体积，通过公式计算求出页岩的总孔隙度。该实验在江汉油田分公司勘探开发研究院石油地质测试中心进行，主要仪器为氦孔隙度测量仪(JS100007)，检测依据为国家标准《岩心分析方法》(GB/T 29172—2012)。
2. 结果与讨论
2.1 微米CT实验中页岩微裂缝的类型与分布
从微米CT实验获取的页岩二维灰度图像中(图 2a、b、c、d、e、f)可见众多微裂缝，它们的形态蜿蜒崎岖，缝面粗糙，偶见分叉状，均为区域构造应力作用在页岩中形成的张性微裂缝[42-44]。每个页岩样品中均发育1~4条主要的微裂缝，呈线状切穿灰白色矿物基质颗粒，微裂缝之间呈现为近平行状，沿着页岩的层理面延伸(图 2d)。由于页岩中含有大量片状黏土矿物颗粒，矿物的排列呈层性，而矿物颗粒边缘为力学薄弱面，成为微裂缝发育与延伸的主要路径。微裂缝均呈现灰黑色，显示出密度低值，说明其中无物质充填，能够成为页岩气储集与渗流的孔隙空间。
![]()
图 2 页岩样品中的典型微裂缝图版a—YL4-6，可见两条微裂缝，其中一条呈现分叉状; b—YL4-10，可见一条微裂缝; c—YB102-7，可见一条微裂缝; d—FY1-9，可见四条近平行状微裂缝; e—FY1-13，可见两条微裂缝，微裂缝的开度较大; f—YB176-7，可见一条主要的微裂缝; g—FY1-13，可见两条主要的微裂缝，三维空间呈层状并且相互连接; h—YL176-7，可见一条主要的微裂缝，三维空间呈层状，同时可见众多微米级孔隙; i—YL4-10，可见一条微裂缝，三维空间内成层性不明显，同时可见众多微米级孔隙。Figure 2. Typical micro-fracture plates in shale samples从页岩孔隙与微裂缝的三维模型(图 2g、h、i)来看，三维空间中弥散分布着大量微米级孔隙(图 2g、h、i)，这些孔隙呈现点状与近圆状，数量庞大，粒径细小，相互之间存在一定距离，可以说明页岩中大量的基质孔隙的连通性较弱，这与页岩储层致密相对应。微裂缝在三维空间上呈现为层状(图 2h)，相互交叉沟通，发育时形成网络状(图 2g)，微裂缝的发育有利于沟通页岩中的大量连通性较弱的基质孔隙空间，提高储层整体的渗透性与储集能力。
根据对二维图像中微裂缝的缝宽的统计(图 3)，微米CT中识别出的微裂缝缝宽主要位于0~32μm(占比99.6%)，其中缝宽在0~12μm的微裂缝占比94.0%，缝宽在12~32μm的微裂缝占比5.7%。说明页岩中微裂缝的缝宽在微米级，集中在0~12μm，该实验结果与前人的认识一致[30-31]。
![]()
图 3 微米CT实验微裂缝的缝宽统计Figure 3. Width statistics of micro-fractures in micro-CT experiment2.2 微米CT实验微裂缝孔隙度计算的误差分析
微裂缝在微米CT图像上是连续变化的[25-28]，在垂直方向的变化差异对微裂缝面孔率的统计存在一定影响。理论上来说，每个样品中选取的切片越密集，求取的微裂缝孔隙度越接近于真实的微裂缝孔隙度，然而其工作量也越庞大。为了提高数据处理的可操作性，本文采用每20张选取一张切片的方法，该方法求取的微裂缝孔隙度存在一定误差，此节针对该方法的误差进行分析。
为了形象地说明垂向上微裂缝的变化对统计结果的影响，本文选取YL176-7样品的第0~20张切片进行分析与统计。二维图像中主要发育4条微裂缝(图 4b、c、d)，其中主要为1号微裂缝与2号微裂缝(图 4a)，其位于图像的中部，延伸较长，3号微裂缝与4号微裂缝位于图像中下部，延伸较短。随着图像序列的递增，1号微裂缝与2号微裂缝在每张切片中的形态与长度变化不大，而从第10张切片以后(图 4b、c、d)，图像中不仅有1号微裂缝与2号微裂缝，3号微裂缝与4号微裂缝同时开始发育。
![]()
图 4 YL176-7样品的部分二维切片a—YL176-7-5，第5张切片可见1号微裂缝与2号微裂缝; b—YL176-7-10，第10张切片可见1号微裂缝、2号微裂缝、3号微裂缝与4号微裂缝; c—YL176-7-15，第15张切片可见四条微裂缝，其中3号微裂缝与4号微裂缝逐渐增长; d—YL176-7-20，第20张切片可见四条微裂缝，其中3号微裂缝与4号微裂缝逐渐增长。Figure 4. Part of the two-dimensional slices of YL176-7 sample根据对每张切片的面孔率统计(图 5)，随着图像序列的递增，0~10张切片的面孔率测量值基本稳定在0.578%~0.667%，说明当时微裂缝的面孔率较为稳定。在第10~20张切片中，由于3号与4号微裂缝的发育，微裂缝的面孔率逐渐增长到0.683%~0.805%。由此可见，20张切片内，测得微裂缝的面孔率约在0.578%~0.805%，微裂缝的面孔率变化较小，微裂缝在垂直方向的变化差异不影响微裂缝面孔率统计。同时本文选取多张切片进行测量，有利于提高孔隙度测量的精度。
![]()
图 5 YL176-7样品的前20张切片统计结果Figure 5. Statistical results of the first 20 photos of YL176-7 sample2.3 页岩中微裂缝占总孔隙空间的比例分析
元坝地区大安寨段页岩中主要发育构造微裂缝(图 2)，而微米CT实验无法给出其准确的微裂缝孔隙度，因此通过人工方法对页岩中的构造微裂缝进行精确统计(图 1)。用页岩的氦气孔隙度评价页岩的总孔隙度，微裂缝的孔隙度除以页岩的总孔隙度，可以评价微裂缝占总孔隙空间的比例。
不同方法的测试结果(表 2)显示，微米CT实验测得的页岩孔隙度普遍小于2.50%，大多数在1.27%~2.46%，由于其仅对页岩中微米级的孔隙与微裂缝进行表征，故远小于页岩的氦气孔隙度值。由于微米CT测量的主要是微裂缝，前人采用微米CT孔隙度评价页岩的微裂缝发育程度具有一定的道理[24-25]。通过人工方法测得的微裂缝的孔隙度普遍小于1.50%，大多数在0.25%~1.06%，此值相比微米CT孔隙度较小。由于针对页岩中构造微裂缝进行表征，除去了部分微米级别孔隙的影响，该值对于微裂缝的定量评价相对于微米CT孔隙度更加有效。
表 2 页岩孔隙组成分析结果Table 2. Analytical results of porosity compositions of shale研究地区 样品编号 CT孔隙度(%) 氦气孔隙度(%) 微裂缝孔隙度(%) 微裂缝占总孔的比例(%) 基质孔隙度(%) 基质孔隙占总孔的比例(%) 涪陵地区 FY1-9 1.49 5.02 0.78 15.54 4.24 84.46 FY1-13 4.74 - 4.32 - - - 元坝地区 YB102-7 2.46 4.60 0.93 20.22 3.67 79.78 YL171-5 1.27 2.24 0.25 11.16 1.99 88.84 YL176-7 1.84 3.45 0.83 24.06 2.62 75.94 YL4-6 1.69 2.93 1.04 35.49 1.89 64.51 YL4-10 1.53 4.16 1.06 25.48 3.10 74.52 元坝地区大安寨段页岩孔隙组成的分析结果(表 2)显示，页岩的氦气孔隙度为2.24%~4.60%，平均3.48%，其中微裂缝孔隙度为0.25%~1.06%，平均0.82%，在总孔隙空间中占比11.16%~35.49%，平均占比23.28%；基质孔隙度为1.89%~3.67%，平均2.65%，在总孔隙空间中占比64.51%~88.84%，平均占比76.72%。页岩以基质孔隙为主，同时微裂缝发育，这与前人的基本认识一致[34-35]。涪陵地区大安寨段页岩中微裂缝同样非常发育，FY1-9的实验结果显示，页岩的总孔隙度为5.02%，其中构造微裂缝孔隙度为0.78%，占比15.54%；基质孔隙度为4.24%，占比84.46%。FY1-13的构造微裂缝的孔隙度高达4.32%，而导致氦气孔隙度无法准确测量。
邹才能等[45]通过建立四川盆地龙马溪组页岩的双孔隙介质模型分析认为，页岩的总孔隙度平均为4.9%~5.8%，其中基质孔隙度平均为4.6%~5.4%，微裂缝孔隙度与区域构造有关。在构造条件复杂的焦石坝地区，页岩中微裂缝孔隙非常发育，平均孔隙度为0.3%~1.3%，占页岩总孔隙空间的6.1%~22.4%，而在构造条件较为稳定的长宁与威远等地区，页岩中微裂缝孔隙度仅为平均0.1%，占页岩总孔隙空间的1.7%~2.0%。由此可见，元坝地区陆相大安寨段页岩中微裂缝的发育程度与构造条件复杂的焦石坝地区海相龙马溪组页岩相近。
2.4 页岩的储集空间对于页岩气富集高产的影响
如2.3节所述，元坝地区大安寨段页岩主要为孔隙型储层(基质孔隙占总孔隙度的比例平均为76.72%)，其储集空间主要为大量纳米尺度的基质孔隙，在扫描电镜下可以看到大量的有机质孔隙、黏土矿物晶间孔隙与脆性矿物颗粒间孔隙等多种类型[38]，在页岩的高压压汞和气体吸附综合分析中，页岩的总孔隙度达到平均11.6×103cc/g，孔径集中在0~50nm[46-48]，基质孔隙的发育有利于页岩气在孔隙空间中的吸附与游离，页岩的基质孔隙度(1.89%~3.67%，平均2.65%)适中，具备页岩气稳产的孔隙条件与良好的页岩气勘探潜力。元坝地区位于四川盆地内部的川北坳陷与川中低缓构造带结合部，区内构造变形弱，与孔隙型储层相对应，页岩气的保存条件良好。
同时，页岩中发育微米尺度的构造微裂缝，并且微裂缝占总孔隙度的比例平均为23.28%，微裂缝的发育程度适当，有利于沟通页岩中大量孤立的纳米基质孔隙空间，改善页岩的储集性能利于页岩气的高产。本区页岩气富集模式属于“构造型甜点”，后期的区域构造运动是页岩中微裂缝形成的主因，成岩收缩与有机质生烃等作用为页岩中微裂缝形成的次要因素，区内大安寨段经历燕山、喜山多期次的构造运动，构造抬升岩石卸压而在页岩中产生大量的构造微裂缝(图 2a、b、c、d、e、f)。页岩的组成、结构与岩性组合是微裂缝形成的内因，区内大安寨段页岩中含有较多的黏土矿物与脆性矿物，层理发育，非均质性强，常夹有较多灰岩条带，页岩的层理与岩性的突变界面处为微裂缝形成的有利位置(图 2g、h、i)。元坝地区多口钻井在大安寨段常规直井测试获得中高产工业气流，这进一步证实微裂缝对页岩气高产的贡献[49]。
3. 结论
利用微米CT技术可以实现对页岩中微裂缝的定量表征。本文以四川盆地元坝地区大安寨段页岩为研究对象，通过二维图像识别微裂缝的方法积分计算出了微裂缝的孔隙度，结合氦气法孔隙度分析了微裂缝占页岩总孔隙度的比例，从孔隙角度探讨了本区的页岩气勘探潜力。同时解决了微米CT实验中页岩微裂缝识别、分离与孔隙度分析的难题，该计算微裂缝孔隙度的方法可以在其他区域页岩的研究中推广使用。
元坝地区大安寨段页岩中基质孔隙的比例平均为76.72%，说明页岩为孔隙型储层，发育众多的纳米级孔隙空间，页岩的基质孔隙度适中，具备页岩气稳产的孔隙条件。微裂缝占总孔隙度的比例平均为23.28%，微裂缝的发育有利于页岩气的高产。本区页岩具备页岩气的高产稳产的孔隙条件，具有良好的页岩气勘探开发潜力。
-
![]()
图 1 开盖/关盖条件下棕色石灰土、红色石灰土中易提取球囊霉素相关蛋白含量
Figure 1. EE-GRSP content of brown calcareous soil and red calcareous soil under open/closed lid condition
![]()
图 2 不同提取时间下棕色石灰土、红色石灰土的EE-GRSP含量
Figure 2. EE-GRSP content of brown calcareous soil and red calcareous under different extraction time
![]()
图 3 四类石灰土颗粒态有机质(a)、矿物结合态有机质(b)的EE-GRSP含量对比
优化前：121℃和40min; 优化后：123℃和80min。
Figure 3. Comparison of EE-GRSP content from POM (a) and MAOM (b) in four types of calcareous soils. Before optimization: 121℃ and 40min. After optimization: 123℃ and 80min
表 1 不同提取时间和提取温度下棕色石灰土、红色石灰土的EE-GRSP提取量
Table 1 EE-GRSP content of brown calcareous soil and red calcareous soil at different extracting time and temperatures
提取条件 EE-GRSP提取量(mg/g) 棕色石灰土-颗粒态有机质 红色石灰土-颗粒态有机质 棕色石灰土-全土 红色石灰土-全土 121℃，40min 0.456±0.070d 0.288±0.02de 0.7±0.028d 0.276±0.012cd 121℃，60min 0.688±0.045c 0.45±0.027b 0.659±0.039d 0.467±0.083a 121℃，80min 0.733±0.128bc 0.38±0.034c 0.89±0.082c 0.374±0.065abc 123℃，40min 0.641±0.083cd 0.347±0.023cd 0.91±0.074bc 0.397±0.062ab 123℃，60min 0.610±0.025cd 0.294±0.025de 1.05±0.041ab 0.321±0.066bcd 123℃，80min 0.963±0.054a 0.594±0.085a 1.126±0.114a 0.388±0.106ab 125℃，40min 0.581±0.052cd 0.269±0.019e 0.723±0.027d 0.256±0.014d 125℃，60min 0.892±0.021ab 0.387±0.027c 1.158±0.164a 0.439±0.01a 125℃，80min 0.729±0.237bc 0.306±0.016de 0.653±0.078d 0.302±0.005bcd 注：同列不同小写字母表示差异显著(p＜0.05)，含相同字母表示差异不显著。
Note: Different lowercase letters in the same column indicate significant difference (p＜0.05), and the same letters indicate no significant difference.
下载: 导出CSV
-
[1] Chen L, Fang K, Wei B, et al. Soil carbon persistence governed by plant input and mineral protection at regional and global scales[J]. Ecology Letters, 2021, 24(5): 1018−1028. doi: 10.1111/ele.13723
[2] 李大通, 罗雁. 中国碳酸盐岩分布面积测量[J]. 中国岩溶, 1983, 2(2): 147−150. Li D T, Luo Y. Measurement of carbonate rocks distribution area in China[J]. Carsologica Sinica, 1983, 2(2): 147−150.
[3] 李强. 岩溶土壤有机碳库分配、更新及其维持的微生物机制[J]. 微生物学报, 2022, 62(6): 2188−2197. doi: 10.13343/j.cnki.wsxb.20220010 Li Q. Microbial mechanism on distribution, renewal, and maintenance of soil organic carbon pool in karst area[J]. Acta Microbiologica Sinica, 2022, 62(6): 2188−2197. doi: 10.13343/j.cnki.wsxb.20220010
[4] 程子捷, 陈志, 纪超, 等. 基于Citespace的国内外碳汇研究热点与前沿分析[J]. 环境与发展, 2023, 35(6): 18−27. doi: 10.16647/j.cnki.cn15-1369/X Cheng Z J, Chen Z, Ji C, et al. Research progress and frontier analysis of carbon sink at home and abroad based on Citespace[J]. Environment and Development, 2023, 35(6): 18−27. doi: 10.16647/j.cnki.cn15-1369/X
[5] 王应琼, 温庆忠, 王昌命, 等. 基于文献计量分析的生态系统碳汇现状研究[J]. 林业调查规划, 2024, 49(1): 98−107. doi: 10.3969/j.issn.1671-3168.2024.01.018 Wang Y Q, Wen Q Z, Wang C M, et al. Carbon sequestration of ecosystem based on bibliometric analysis[J]. Forest Inventory and Planning, 2024, 49(1): 98−107. doi: 10.3969/j.issn.1671-3168.2024.01.018
[6] 田慧, 刘晓蕾, 盖京苹, 等. 球囊霉素及其作用研究进展[J]. 土壤通报, 2009, 40(5): 1215−1220. doi: 10.19336/j.cnki.trtb Tian H, Liu X L, Gai J P, et al. Review of glomalin-related soil protein and its function[J]. Chinese Journal of Soil Science, 2009, 40(5): 1215−1220. doi: 10.19336/j.cnki.trtb
[7] Yan J H, Li Q, Hu L A, et al. Response of microbial communities and their metabolic functions to calcareous succession process[J]. Science of the Total Environment, 2022, 825: 154020. doi: 10.1016/j.scitotenv.2022.154020
[8] 王建, 周紫燕, 凌婉婷. 球囊霉素相关土壤蛋白的分布及环境功能研究进展[J]. 应用生态学报, 2016, 27(2): 634−642. doi: 10.13287/j.1001-9332.201602.028 Wang J, Zhou Z Y, Ling W T. Distribution and environmental function of glomalin-related soil protein: A review[J]. Chinese Journal of Applied Ecology, 2016, 27(2): 634−642. doi: 10.13287/j.1001-9332.201602.028
[9] Rillig M C. Arbuscular mycorrhizae, glomalin, and soil aggregation[J]. Canadian Journal of Soil Science, 2004, 84(4): 355−363. doi: 10.4141/S04-003
[10] 郭雪佳. 球囊霉素相关土壤蛋白的分离纯化及性质分析[D]. 武汉: 华中农业大学, 2022: 1–69. Guo X J. Purification and characterization of glomalin-related soil protein[D]. Wuhan: Huazhong Agricultural University, 2022: 1–69.
[11] 柴立伟, 刘梦娇, 蒋大林, 等. 北京市不同地区土壤中的球囊霉素荧光特征及其与土壤理化性质的关系[J]. 环境科学, 2016, 37(12): 4806−4814. doi: 10.13227/j.hjkx.201606113 Chai L W, Liu M J, Jiang D L, et al. Fluorescence properties of glomalin and its relationship with soil physicochemical characteristics in different regions of Beijing[J]. Environmental Science, 2016, 37(12): 4806−4814. doi: 10.13227/j.hjkx.201606113
[12] Zhang Z, Wang Q, Wang H, et al. Effects of soil salinity on the content, composition, and ion binding capacity of glomalin-related soil protein (GRSP)[J]. Science of the Total Environment, 2017, 581−582(1): 657−665. doi: 10.1016/j.scitotenv.2016.12.176
[13] Zhang J, Li J, Ma L, et al. Accumulation of glomalin-related soil protein benefits soil carbon sequestration: Tropical coastal forest restoration experiences[J]. Land Degradation & Development, 2022, 33(10): 1541−1551. doi: 10.1002/ldr.4192
[14] Wright S F, Upadhyaya A. A survey of soils for aggregate stability and glomalin, a glycoprotein produced by hyphae of arbuscular mycorrhizal fungi[J]. Plant and Soil, 1998, 198(10): 97−107.
[15] Zhou W, Sun X, Li S, et al. Effects of organic mulching on soil aggregate stability and aggregate binding agents in an urban forest in Beijing, China[J]. Journal of Forestry Research, 2022, 33(3): 1083−1094. doi: 10.1007/s11676-021-01402-z
[16] Li Y, Xu J, Hu J, et al. Arbuscular mycorrhizal fungi and glomalin play a crucial role in soil aggregate stability in Pb-contaminated soil[J]. International Journal of Environmental Research and Public Health, 2022, 19(9): 5029. doi: 10.3390/ijerph19095029
[17] Ji L, Tan W, Chen X. Arbuscular mycorrhizal mycelial networks and glomalin-related soil protein increase soil aggregation in Calcaric Regosol under well-watered and drought stress conditions[J]. Soil and Tillage Research, 2019, 185: 1−8. doi: 10.1016/j.still.2018.08.010
[18] Bedini S, Pellegrino E, Avio L, et al. Changes in soil aggregation and glomalin-related soil protein content as affected by the arbuscular mycorrhizal fungal species Glomus mosseae and Glomus intraradices[J]. Soil Biology and Biochemistry, 2009, 41(7): 1491−1496. doi: 10.1016/j.soilbio.2009.04.005
[19] 张梦歌, 石兆勇, 杨梅, 等. 热带山地雨林土壤球囊霉素的分布特征[J]. 生态环境学报, 2020, 29(3): 457−463. doi: 10.16258/j.cnki.1674-5906.2020.03.004 Zhang M G, Shi Z Y, Yang M, et al. Elevational distribution of glomalin-rated soil proteins in a tropical montane rain forest[J]. Ecology and Environment Science, 2020, 29(3): 457−463. doi: 10.16258/j.cnki.1674-5906.2020.03.004
[20] 杨梅, 石兆勇, 卢世川, 等. 增温对青藏高原草地生态系统土壤球囊霉素含量的影响[J]. 生态环境学报, 2020, 29(4): 650−656. doi: 10.16258/j.cnki.1674-5906.2020.04.002 Yang M, Shi Z Y, Lu S C, et al. Effect of warming on soil glomalin in grassland of the Qinghai—Tibet Plateau[J]. Ecology and Environment Science, 2020, 29(4): 650−656. doi: 10.16258/j.cnki.1674-5906.2020.04.002
[21] Jing H, Meng M, Wang G L, et al. Aggregate binding agents improve soil aggregate stability in Robinia pseudoacacia forests along a climatic gradient on the Loess Plateau, China[J]. Journal of Arid Land, 2021, 13(2): 165−174. doi: 10.1007/s40333-021-0002-8
[22] Li T, Yuan Y, Mou Z, et al. Faster accumulation and greater contribution of glomalin to the soil organic carbon pool than amino sugars do under tropical coastal forest restoration[J]. Global Change Biology, 2023, 29(2): 533−546. doi: 10.1111/GCB.16467
[23] 王琼. 城市森林球囊霉素相关土壤蛋白特征差异研究[D]. 长春: 中国科学院大学(中国科学院东北地理与农业生态研究所), 2019: 1–186. Wang Q. Variation of glomalin-related soil protein characteristics in urban forest in China[D]. Changchun: University of Chinese Academy of Sciences (Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences), 2019: 1–186.
[24] 权常欣, 马玲玲, 林钊凯, 等. 广东省森林球囊霉素相关土壤蛋白含量及影响因素[J]. 生态环境学报, 2020, 29(2): 240−249. doi: 10.16258/j.cnki.1674-5906.2020.02.004 Quan C X, Ma L L, Lin Z K, et al. Patterns and influence factors of glomalin-related soil protein in Guangdong forests[J]. Ecology and Environment Science, 2020, 29(2): 240−249. doi: 10.16258/j.cnki.1674-5906.2020.02.004
[25] Liu H, Wang X, Liang C, et al. Glomalin-related soil protein affects soil aggregation and recovery of soil nutrient following natural revegetation on the Loess Plateau[J]. Geoderma, 2020, 357: 113921. doi: 10.1016/j.geoderma.2019.113921
[26] 邸涵悦, 郝好鑫, 孙兆祥, 等. 不同演替阶段下球囊霉素相关土壤蛋白对团聚体稳定性的影响[J]. 生态环境学报, 2021, 30(4): 718−725. doi: 10.16258/j.cnki.1674-5906 Di H Y, Hao H X, Sun Z X, et al. Effects of glomalin-related soil protein on the stability of aggregates at different succession stages[J]. Ecology and Environ-mental Sciences, 2021, 30(4): 718−725. doi: 10.16258/j.cnki.1674-5906
[27] 甘佳伟, 韩晓增, 邹文秀. 球囊霉素及其在土壤生态系统中的作用[J]. 土壤与作物, 2022, 11(1): 41−53. doi: 10.11689/j.issn.2095-2961.2022.01.005 Gan J W, Han X Z, Zou W X. Glomalin and its roles in soil ecosystem: A review[J]. Soils and Crops, 2022, 11(1): 41−53. doi: 10.11689/j.issn.2095-2961.2022.01.005
[28] 张静, 唐旭利, 郑克举, 等. 赤红壤地区森林土壤球囊霉素相关蛋白测定方法[J]. 生态学杂志, 2014, 33(1): 249−258. doi: 10.13292/j.1000-4890.20131220.0002 Zhang J, Tang X L, Zheng K J, et al. An improved procedure for glomalin-related soil protein measurement in subtropical forest[J]. Chinese Journal of Ecology, 2014, 33(1): 249−258. doi: 10.13292/j.1000-4890.20131220.0002
[29] 高瑞, 牛伊宁, 何仁元, 等. 不同种植年限苜蓿地球囊霉素相关土壤蛋白含量及其影响因素[J]. 草业科学, 2024, 41(3): 700−708. doi: 10.11829/j.issn.1001-0629.2022-0922 Gao R, Niu Y N, He R Y, et al. Content and factors influencing glomalin-related soil protein of alfalfa fields at different growing ages[J]. Pratacultural Science, 2024, 41(3): 700−708. doi: 10.11829/j.issn.1001-0629.2022-0922
[30] 高瑞. 陇中黄土丘陵区长期种植紫花苜蓿土壤AMF群落结构及多样性研究[D]. 兰州: 甘肃农业大学, 2023: 1–58. Gao R. Study on AMF community structure and diversity of long-term planted Alfalfa soil in the loess hilly region of Central Gansu[D]. Lanzhou: Gansu Agricultural University, 2023: 1–58.
[31] 王国禧, 王萍, 刘亚龙, 等. 球囊霉素在土壤团聚体中的分布特征及影响因素的Meta分析[J]. 土壤学报, 2024, 61(4): 1147−1155. doi: 10.11766/trxb202301170024 Wang G X, Wang P, Liu Y L, et al. Distribution characteristics and influencing factors of glomalin in soil aggregates: A meta-analysis[J]. Acta Pedologica Sinica, 2024, 61(4): 1147−1155. doi: 10.11766/trxb202301170024
[32] Wei Q, Gunina A, Kuzyakov Y, et al. Contributions of mycorrhizal fungi to soil aggregate formation during subalpine forest succession[J]. Catena, 2023, 221: 10680. doi: 10.1016/j.catena.2022.106800
[33] Tang Q, Li Q, Tong L, et al. Rhizospheric soil organic carbon accumulated but its molecular groups redistributed via rhizospheric soil microorganisms along multi-root Cerasus humilis plantation chronosequence at the karst rocky desertification control area[J]. Environmental Science and Pollution Research, 2023, 30(5): 72993−73007.
[34] Angst G, Mueller K E, Castellano M J, et al. Unlocking complex soil systems as carbon sinks: Multi-pool management as the key[J]. Nature Communications, 2023, 14(1): 2967. doi: 10.1038/s41467-023-38700-5
[35] Yuan B, Li H, Hong H, et al. Immobilization of lead(Ⅱ) and zinc(Ⅱ) onto glomalin-related soil protein (GRSP): Adsorption properties and interaction mechanisms[J]. Ecotoxicology and Environmental Safety, 2022, 236: 113489. doi: 10.1016/j.ecoenv.2022.113489
[36] Cissé G, Essi M, Nicolas M, et al. Bradford quantification of glomalin-related soil protein in coloured extracts of forest soils[J]. Geoderma, 2020, 372(5): 114394. doi: 10.1016/j.geoderma.2020.114394
[37] 欧阳永忠. 分光光度法在岩矿元素测试的应用分析[J]. 中国金属通报, 2022, 30(6): 237−239. doi: 10.3969/j.issn.1672-1667.2022.11.078 Ouyang Y Z. Application of spectrophotometric method for testing elements in mineral and rock[J]. China Metal Bulletin, 2022, 30(6): 237−239. doi: 10.3969/j.issn.1672-1667.2022.11.078
[38] Koide R T, Peoples M S. Behavior of Bradford-reactive substances is consistent with predictions for glomalin[J]. Applied Soil Ecology, 2013, 63(9): 8−14. doi: 10.1016/j.apsoil.2012.09.015
[39] 温云杰, 刁风伟, 高敏, 等. 有机物料与土壤质地对土壤球囊霉素的影响[J]. 山西农业科学, 2022, 50(8): 1176−1183. doi: 10.3969/j.issn.1002-2481.2022.08.15 Wen Y J, Diao F W, Gao M, et al. Influence of organic amendments types and soil texture on soil glomalin[J]. Journal of Shanxi Agricultural Sciences, 2022, 50(8): 1176−1183. doi: 10.3969/j.issn.1002-2481.2022.08.15
[40] 舒宝生, 万勇, 汪晓红. 关于热力学中热力学能和热力学焓的讨论[J]. 黄冈师范学院学报, 2020, 40(3): 108−110. doi: 10.3969/j.issn.2096-7020.2020.03.21 Shu B S, Wan Y, Wang X H. Understanding about thermodynamic energy and thermodynamic enthalpy[J]. Journal of Huanggang Normal University, 2020, 40(3): 108−110. doi: 10.3969/j.issn.2096-7020.2020.03.21
[41] 谢小林, 许朋阳, 朱红惠, 等. 球囊霉素相关土壤蛋白的提取条件[J]. 菌物学报, 2011, 30(1): 92−99. doi: 10.13346/j.mycosystema.2011.01.010 Xie X L, Xu P Y, Zhu H H, et al. Extraction conditions of glomalin-related soil protein[J]. Mycosystema, 2011, 30(1): 92−99. doi: 10.13346/j.mycosystema.2011.01.010
[42] 任闻达. AM真菌和物种丰富度调控斑块异质性土壤理化性质研究[D]. 贵阳: 贵州大学, 2023: 1–81. Ren W D. AM fungi and species richness control soil physicalchemical properties relating to heterogeneity conditions[D]. Guiyang: Guizhou University, 2023: 1–81.
[43] 张治伟, 许娟娟, 严焕德, 等. 海拔与岩性变异对石灰岩发育土壤黏土矿物组成的影响[J]. 土壤学报, 2017, 54(2): 535−542. doi: 10.11766/trxb201607250297 Zhang Z W, Xu J J, Yan H D, et al. Effects of elevation and lithology on clay mineral composition of soils derived from limestone[J]. Acta Pedologica Sinica, 2017, 54(2): 535−542. doi: 10.11766/trxb201607250297
[44] 顾新运, 许冀泉. 中国土壤胶体研究 Ⅴ. 滇桂地区石灰岩发育的三种土壤的粘土矿物组成和演变[J]. 土壤学报, 1963, 11(4): 411−416. Gu X Y, Xu J Q. Soil colloid researches Ⅴ. Clay minerals and their transformations in Rendzina, Terra Fusca and Terra Rossa of Yunnan and Kwangsi[J]. Acta Pedologica Sinica, 1963, 11(4): 411−416.
[45] 胡清菁, 张超兰, 靳振江, 等. 铅锌矿尾砂重金属污染物对不同土地利用类型土壤性质影响的典范对应分析[J]. 岩矿测试, 2014, 33(5): 714−722. doi: 10.15898/j.cnki.11-2131/td Hu Q J, Zhang C L, Jin Z J, et al. Canonical correspondence analysis for soil properties and heavy metal pollution from Pb-Zn mine tailings in different land use types[J]. Rock and Mineral Analysis, 2014, 33(5): 714−722. doi: 10.15898/j.cnki.11-2131/td
[46] 何开平, 杜鹏, 吴强盛. 球囊霉素相关土壤蛋白提取条件的优化[J]. 长江大学学报(自科版), 2015, 12(33): 25−28,5. doi: 10.16772/j.cnki.1673-1409.2015.33.016 He K P, Du P, Wu Q S. Optimization of extraction techniques for glomalin-related soil protein[J]. Journal of Yangtze University (Natural Science Edition), 2015, 12(33): 25−28,5. doi: 10.16772/j.cnki.1673-1409.2015.33.016
[47] 沈育伊, 滕秋梅, 徐广平, 等. 桂林会仙岩溶湿地土地利用方式对球囊霉素相关土壤蛋白分布的影响[J]. 地球学报, 2022, 43(4): 491−501. doi: 10.3975/cagsb.2022.012701 Shen Y Y, Teng Q M, Xu G P, et al. Effects of land use type on distribution of glomalin-related soil protein in the Huixian karst wetland, Guilin[J]. Acta Geoscientica Sinica, 2022, 43(4): 491−501. doi: 10.3975/cagsb.2022.012701
[48] Angst G, Mueller K E, Nierop K G J, et al. Plant-or microbial-derived? A review on the molecular composition of stabilized soil organic matter[J]. Soil Biology and Biochemistry, 2021, 156: 108189. doi: 10.1016/j.soilbio.2021.108189
[49] Wang Q, Chen J, Chen S, et al. Terrestrial-derived soil protein in coastal water: Metal sequestration mechanism and ecological function[J]. Journal of Hazardous Materials, 2020, 386: 121655. doi: 10.1016/j.jhazmat.2019.121655
-
期刊类型引用(1)
1. 王俊杰，王巧环，熊满艳，宋祥梅，王美娥，傅慧敏，李虹，孟龄. 银杯消解-元素分析仪法测定土壤和沉积物中有机碳. 岩矿测试. 2024(06): 936-944 . 
本站查看
其他类型引用(0)
计量
- 文章访问数: 92
- HTML全文浏览量: 22
- PDF下载量: 42
- 被引次数: 1
京公网安备 11010202008159号