本文選題：總有機(jī)碳 + 黑碳��； 參考：《中國(guó)科學(xué)院研究生院(廣州地球化學(xué)研究所)》2015年碩士論文

【摘要】：黑碳(BC)是生物質(zhì)和化石燃料等不完全燃燒產(chǎn)生的含碳物質(zhì)。黑碳在生物地球化學(xué)循環(huán)中有著非常重要的作用,也是全球碳循環(huán)中重要的源和匯。古老沉積物中黑碳的記錄可以重建過(guò)去的火災(zāi)和陸地植被演化歷史,也可以間接獲得過(guò)去大氣中氧氣濃度。在前期工作的基礎(chǔ)上,本文以古老地質(zhì)樣品為研究對(duì)象,首先對(duì)樣品中總有機(jī)碳(TOC)的測(cè)定和黑碳的分離方法進(jìn)行了研究與改進(jìn),然后使用改進(jìn)后的方法對(duì)松遼盆地白堊紀(jì)地層中(以青山口組和嫩江組為例)的TOC和BC含量進(jìn)行測(cè)定,對(duì)當(dāng)時(shí)的火災(zāi)歷史和古氣候特征進(jìn)行了初步的探討。獲得的主要認(rèn)識(shí)和結(jié)論如下:1、總有機(jī)碳是土壤和沉積物等樣品的重要指標(biāo),然而預(yù)處理方法對(duì)樣品TOC值的最終測(cè)定會(huì)產(chǎn)生一定的影響。針對(duì)這個(gè)問(wèn)題,本論文主要從酸處理方式、干燥過(guò)程等方面研究了預(yù)處理方法對(duì)不同類(lèi)型樣品的TOC含量和穩(wěn)定碳同位素(δ13C值)測(cè)定的影響。研究結(jié)果顯示:酸處理方式對(duì)TOC含量測(cè)定的影響很大,Ag杯和鹽酸酸化/分離未去除殘留酸液兩組實(shí)驗(yàn)所測(cè)得TOC含量明顯大于其他組。這種差異可能是樣品酸處理過(guò)程中水溶性有機(jī)碳(DOC)的損失所造成的。對(duì)于δ13C測(cè)定來(lái)說(shuō),該兩組實(shí)驗(yàn)所測(cè)得δ13C相對(duì)于其他組略微偏重。另外加熱干燥和真空冷凍干燥方式測(cè)定的TOC含量和δ13C值沒(méi)有明顯的變化,表明了揮發(fā)性有機(jī)物對(duì)本次實(shí)驗(yàn)所選用樣品的有機(jī)碳分析影響甚微。綜合來(lái)看,對(duì)于含有較多DOC的現(xiàn)代樣品來(lái)說(shuō),Ag杯法是比較好的選擇;對(duì)于含DOC很少的古老地質(zhì)樣品來(lái)說(shuō),樣品的預(yù)處理方法對(duì)樣品的最終測(cè)定影響相對(duì)較小,可根據(jù)實(shí)驗(yàn)條件選擇最方便快捷的方法。2、鉻酸化學(xué)氧化法和熱氧化法(CTO-375)是地質(zhì)樣品中黑碳的常用測(cè)定方法,但這兩種方法都存在一些缺點(diǎn),比如化學(xué)氧化法會(huì)把高成熟度的干酪根誤判為黑碳,從而高估了黑碳的含量,而CTO-375方法也存在有機(jī)碳焦化的現(xiàn)象。針對(duì)這些問(wèn)題,本文選擇低成熟度的Ⅰ型和Ⅲ型干酪根作為基礎(chǔ)樣品,通過(guò)熱模擬制備了兩套不同成熟度的干酪根,然后以這兩套樣品為參考物,對(duì)傳統(tǒng)鉻酸氧化法分離BC和CTO-375熱氧化法分離soot-BC進(jìn)行了系統(tǒng)對(duì)比和優(yōu)化,研究結(jié)果顯示:(1)分離含有Ⅰ型干酪根的沉積物樣品中的BC,干酪根成熟度低于1.25%時(shí)傳統(tǒng)的鉻酸氧化法可很好的去除干酪根,在成熟度0.38-0.89%時(shí)使用傳統(tǒng)的鉻酸氧化法處理氧化時(shí)間需要延長(zhǎng)到120 h;而成熟度在0.89-1.25%時(shí)將氧化時(shí)間延長(zhǎng)到300 h;成熟度高于1.25%時(shí),該法具有一定的局限性。對(duì)于Ⅲ型干酪根來(lái)說(shuō),鉻酸氧化法的去除效果較差,表明Ⅲ型干酪根含有部分抗氧化性的碳質(zhì)組分。這種現(xiàn)象意味著Ⅲ型干酪根可能會(huì)對(duì)鉻酸氧化法分離沉積物中黑碳造成較大的干擾。但總的來(lái)說(shuō)對(duì)含有低成熟度Ⅲ型干酪根的樣品,傳統(tǒng)鉻酸氧化法還是可以謹(jǐn)慎使用的;(2)針對(duì)成熟度高于1.25%的樣品,從氧化劑濃度方面對(duì)傳統(tǒng)鉻酸氧化法進(jìn)行優(yōu)化,初步的結(jié)果表明提高氧化劑濃度可以有效地改善鉻酸氧化法的效率;(3)使用CTO-375熱氧化法分離沉積物中soot-BC時(shí),干酪根對(duì)其并不造成影響,但其具體的處理方式有待進(jìn)一步改進(jìn)。3、采用改進(jìn)的鉻酸氧化法和常規(guī)CTO-375法對(duì)松遼盆地白堊紀(jì)嫩江組和青山口組樣品中黑碳記錄進(jìn)行了研究,來(lái)重建這段時(shí)期松遼盆地的湖泊及周邊區(qū)域內(nèi)火災(zāi)的頻次和規(guī)模以及火山噴發(fā)事件等。結(jié)果表明:(1)青山口組:桻一段的TOC和BC含量都非常低,可能是由于鳥(niǎo)河剖面位于整個(gè)松遼盆地湖泊的邊緣,湖水較淺,有機(jī)質(zhì)和黑碳都不利于保存;桻一段上部TOC組分中BC所占的比例由下至上逐漸升高,這可能是由于從青一段到青二段氣候逐漸干旱導(dǎo)致。在青二段下部BC含量有一處大幅度升高,其升高的強(qiáng)度大于TOC增加的強(qiáng)度,推測(cè)該時(shí)間段有頻繁火災(zāi)事件發(fā)生,且根據(jù)前人研究該段發(fā)現(xiàn)火山灰層,因此該時(shí)間段的火災(zāi)可能與頻繁的火山活動(dòng)有關(guān)。(2)嫩江組:根據(jù)嫩江組BC的記錄,在嫩一中下部,BC的豐度升高,其升高的強(qiáng)度大于TOC增加的強(qiáng)度,推測(cè)該時(shí)間段有頻繁火災(zāi)事件發(fā)生,且根據(jù)前人研究該段發(fā)現(xiàn)火山灰層,因此該時(shí)間段的火災(zāi)可能與頻繁的火山活動(dòng)有關(guān)。在嫩一段上部,TOC和BC的豐度都處于較低的水平,可能是由于嫩一段中部至上部,湖水逐漸變淺,相對(duì)更不利于有機(jī)質(zhì)的保存。在嫩二段BC具有明顯較高的含量,且波動(dòng)范圍很大,反映這一段存在明顯強(qiáng)烈的火災(zāi)事件。而在同一時(shí)期,TOC的含量也很高,反映這段時(shí)間生物量非常大。另外由于海侵事件大量陸地上沉積的BC被帶入湖泊中被沉積下來(lái),且海侵使湖水變深,使得BC和TOC都很好的保存下來(lái)。至嫩二段中部,TOC和BC的豐度都有下降的趨勢(shì),可能該時(shí)期的氣候逐漸干涼。嫩一段下部可能發(fā)生了小規(guī)模的劇烈大火事件。
[Abstract]:Black carbon (BC) is a carbon containing substance produced by incomplete combustion of biomass and fossil fuels. Black carbon plays a very important role in the biogeochemical cycle. It is also an important source and sink in the global carbon cycle. The record of black carbon in ancient sediments can reconstruct the history of the evolution of past fires and terrestrial vegetation, and can also be indirectly obtained in the past. The concentration of oxygen in the atmosphere. On the basis of the earlier work, this paper takes ancient geological samples as the research object. First, the determination of total organic carbon (TOC) and the method of black carbon separation are studied and improved. Then the improved method is used for the TOC and BC containing in the Cretaceous layer of the Songliao Basin (with the Qingshankou group and the Nenjiang group as an example). The main understanding and conclusions obtained are as follows: 1, total organic carbon is an important indicator of soil and sediment samples. However, the pretreatment method will have a certain effect on the final determination of the TOC value of the sample. The effects of pretreatment methods on the content of TOC and the determination of stable carbon isotopes (delta 13C values) of different types of samples were studied. The results showed that the effect of acid treatment on the determination of TOC content was great, and the content of TOC in the two groups of Ag cup and hydrochloric acid acidification / separation without removing residual acid solution was obviously greater than that of the others. This difference may be caused by the loss of water-soluble organic carbon (DOC) in the sample acid treatment. For the delta 13C determination, the two groups of experiments have measured slightly partial weight of the delta 13C relative to the other groups. In addition, the TOC content and delta 13C value determined by the heating drying and vacuum freeze drying methods have not changed significantly, indicating the volatile organic compounds. There is little influence on the organic carbon analysis of the samples selected in this experiment. For the modern samples containing more DOC, the Ag cup method is a better choice. For the old geological samples with little DOC, the pre treatment method of the sample is relatively small for the final determination of the sample, and it can be chosen most convenient according to the experimental conditions. Fast methods.2, chromic acid chemical oxidation and thermal oxidation (CTO-375) are common methods for determining black carbon in geological samples, but there are some shortcomings in these two methods. For example, chemical oxidation can misjudge the high maturity kerogen as black carbon, so that the content of black carbon is overestimated, and CTO-375 method also has the phenomenon of organic carbon coking. In order to solve these problems, two sets of kerogen with different maturity were prepared by thermal simulation with low maturity type I and type III kerogen as the base sample. Then the two sets of samples were used as reference materials to compare and optimize the separation of soot-BC by traditional chromic acid oxidation method BC and CTO-375 thermal oxidation method. The results showed that the results were obvious. (1) separation of BC in the sediment samples containing type I kerogen, and the traditional chromic acid oxidation method can remove the kerogen well when the maturity of kerogen is less than 1.25%, while the oxidation time of the traditional chromic acid oxidation process needs to be prolonged to 120 h when the maturity is 0.38-0.89%, while the maturity is extended to 300 h when the maturity is at 0.89-1.25%. When the maturity is higher than 1.25%, the method has some limitations. For the type III kerogen, the removal of chromic acid oxidation method is poor, indicating that type III kerogen contains some antioxidant carbon components. This phenomenon implies that type III kerogen may interfere with the black carbon in the sediment by chromic acid oxidation method. For samples containing low maturity type III type kerogen, traditional chromic acid oxidation method can be used carefully. (2) the traditional chromic acid oxidation process is optimized from the concentration of oxidant for the samples with higher maturity than 1.25%. The preliminary results show that improving the oxidizing agent concentration can effectively improve the efficiency of chromic acid oxidation process; (3) use C. When TO-375 thermal oxidation is used to separate soot-BC from the sediments, the kerogen does not affect it, but its specific treatment needs to be further improved by.3. The modified chromic acid oxidation method and the conventional CTO-375 method are used to study the black carbon record in the Cretaceous Nenjiang and Qingshankou formation samples of the Songliao Basin, to reconstruct the Songliao Basin during this period. The frequency and scale of fire in the lake and its surrounding area and volcanic eruption events show that: (1) the content of TOC and BC in the Qingshankou group is very low, maybe because the bird river section is located at the edge of the lake in the whole Songliao Basin, the lake water is shallow, the organic matter and the black carbon are not good for preservation, and the BC in the upper TOC component of the upper section is accounted for. The proportion of BC is gradually rising from the bottom to the top, which may be due to the gradual drought from the Qingyi to the green section. In the lower part of the two section of the Qing Dynasty, there is a large increase in the BC content in the lower part of the two section of the Qing Dynasty. The fire in the interval may be related to frequent volcanic activity. (2) Nenjiang group: according to the record of the Nenjiang group BC, the abundance of BC in the lower middle part of Nen is higher than that of TOC. It is suggested that there are frequent fire events in this period, and the fire possibility of this period is possible according to the discovery of the volcanic ash layer in this section. It is related to frequent volcanic activity. The abundance of TOC and BC at the upper part of the tender section is at a lower level, which may be due to the shallow water of the middle to the upper part of the tender one, which is relatively less conducive to the preservation of the organic matter. In the two part of the tender section, the BC has a significantly higher content and a wide range of fluctuations, reflecting the obvious and intense fire incident in this section. And in the same period, the content of TOC is very high, reflecting the very large biomass in this period. In addition, as a result of the transgression events, a large amount of land deposited on land has been deposited in the lake, and the transgression makes the lake water deep, so that both BC and TOC are well preserved. The abundances of TOC and BC have a downward trend in the middle part of the two tenderness, possibly the same. During the period, the climate gradually cooled down. A small and severe fire occurred in the lower part of the Nen.
【學(xué)位授予單位】：中國(guó)科學(xué)院研究生院(廣州地球化學(xué)研究所)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：P595;P534.53

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 曹蘊(yùn)寧,劉衛(wèi)國(guó),寧有豐,張慶樂(lè),王政;土壤有機(jī)碳同位素樣品制備過(guò)程的影響因素討論[J];地球化學(xué);2005年04期

2 方大鈞,葉德泉;中國(guó)松遼盆地白堊紀(jì)巖石磁化率、剩磁強(qiáng)度與古氣候意義[J];地球物理學(xué)報(bào);1989年01期

3 王璞s，

本文編號(hào)：1950641