發(fā)布時(shí)間：2018-07-11 13:10

  本文選題：DOC + δ13CDOC��； 參考：《國(guó)家海洋局第三海洋研究所》2015年碩士論文

【摘要】：碳循環(huán)是研究全球生物地球化學(xué)循環(huán)中最核心的一個(gè)環(huán)節(jié),涉及到大氣圈、陸地生物圈、水圈和巖石圈。河流作為連接地球上海洋和陸地這兩個(gè)碳庫(kù)最重要的紐帶,是將陸地含碳物質(zhì)輸送到海洋的主要通道。因此,研究河流中碳循環(huán)過(guò)程對(duì)了解碳的生物地球化學(xué)循環(huán)過(guò)程具有重要意義,而穩(wěn)定同位素技術(shù)則對(duì)研究碳的來(lái)源提供了技術(shù)手段。本文研究了一種能同時(shí)測(cè)定溶解有機(jī)碳(DOC)含量及其同位素(δ13CDOC)的方法——濕氧化-質(zhì)譜法。該方法利用常規(guī)水化學(xué)的方法(濕氧化法),配合實(shí)驗(yàn)室現(xiàn)有在線制樣裝置(Gas Bench II)和穩(wěn)定同位素質(zhì)譜儀(IRMS),用于測(cè)定水體中DOC含量和δ13CDOC值。經(jīng)過(guò)多次實(shí)驗(yàn),在不同條件下對(duì)該方法進(jìn)行分析測(cè)試其穩(wěn)定性后,將其用于九龍江西溪和北溪與河口區(qū)表層水體中DOC含量及δ13CDOC值測(cè)定,并對(duì)其變化規(guī)律及來(lái)源進(jìn)行了探討,獲得了以下幾點(diǎn)認(rèn)識(shí):1.實(shí)驗(yàn)結(jié)果表明,濕氧化-質(zhì)譜法對(duì)空白和DOC標(biāo)準(zhǔn)物質(zhì)的同位素測(cè)試結(jié)果穩(wěn)定,可以應(yīng)用于DOC碳同位素的測(cè)定。該方法在1.0 ml氧化劑量、100℃氧化溫度的條件下,DOC標(biāo)準(zhǔn)物質(zhì)的碳回收率及δ13CDOC值穩(wěn)定性較好,但δ13CDOC值受空白的影響都出現(xiàn)明顯分餾。當(dāng)DOC標(biāo)準(zhǔn)物質(zhì)的濃度逐漸升高時(shí),δ13CDOC值逐漸接近其真實(shí)值,但碳的回收率表現(xiàn)為降低的趨勢(shì)。2.西溪表層水體DOC含量季節(jié)變化為春季(5.56 mg/L)高于夏季(3.38mg/L),δ13CDOC值表現(xiàn)為春季(-13.11‰)高于夏季(-15.38‰);空間變化為春季DOC含量和δ13CDOC值均沿河道逐漸遞增,下游高于上游,夏季DOC含量和δ13CDOC值無(wú)明顯變化趨勢(shì)。北溪表層水體中DOC含量季節(jié)變化為春季(2.18mg/L)低于夏季(4.85 mg/L),δ13CDOC值為春季(-12.91‰)低于夏季(-12.37‰);空間變化為春夏季DOC含量沿河道從上游逐漸降低,在臨近河口區(qū)時(shí),含量有回升趨勢(shì);δ13CDOC值春季無(wú)明顯變化趨勢(shì),夏季沿河道逐漸降低。3.河口區(qū)表層水體DOC含量季節(jié)變化為春季(5.13 mg/L)低于夏季(6.68mg/L);表層水體中δ13CDOC值為春季(-12.38‰)低于夏季(-8.74‰)。春夏季DOC含量和δ13CDOC值空間變化表現(xiàn)為隨河道從上游地區(qū)到下游地區(qū)均呈升高趨勢(shì),在近海端均有高DOC含量和高δ13CDOC值。
[Abstract]:The carbon cycle is the core of the global biogeochemical cycle, involving the atmosphere, terrestrial biosphere, hydrosphere and lithosphere. As the most important link between the two carbon pools on the earth, rivers are the main way to transport carbon-containing matter from land to ocean. Therefore, the study of carbon cycling in rivers is of great significance in understanding the biogeochemical cycling process of carbon, while stable isotope technology provides a technical means for studying the source of carbon. A method for simultaneous determination of dissolved organic carbon (DOC) and its isotopes (未 13 CDOC) by wet oxidation-mass spectrometry has been studied. This method is used to determine DOC content and 未 13 CDOC value in water by conventional hydrochemical method (wet oxidation method), gas Bench II and stable isotope mass spectrometer (IRMS). After many experiments, the stability of the method was analyzed and tested under different conditions. The method was applied to the determination of DOC content and 未 13 CDOC value in the surface water of Xixi, Beixi and estuary areas of Jiulong River, and its variation law and source were discussed. The following points of understanding have been gained: 1. The experimental results show that the isotopic measurements of blank and DOC reference materials by wet oxidation-mass spectrometry are stable and can be applied to the determination of DOC carbon isotopes. The method has good stability of carbon recovery and 未 13 CDOC values of DOC standard materials at oxidation temperature of 100 鈩，

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