本文關(guān)鍵詞：近海溶解態(tài)硒及其同位素的生物地球化學(xué)過程　出處：《華東師范大學(xué)》2017年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 溶解態(tài)硒 形態(tài)分析 硒穩(wěn)定同位素 長江口 東海陸架 桑溝灣 硒同位素分餾 食物鏈傳遞

【摘要】：痕量元素在海洋生態(tài)系統(tǒng)中起著舉足輕重的作用,是海洋科學(xué)乃至全球環(huán)境變化研究的重點(diǎn)領(lǐng)域,而且非傳統(tǒng)穩(wěn)定同位素也是國際上同位素研究的一個(gè)前沿領(lǐng)域。硒是多種生物必需的營養(yǎng)元素,濃度高時(shí)會產(chǎn)生毒性效應(yīng),而且能夠沿食物鏈傳遞富集。研究海洋中硒的分布及其沿食物鏈的傳遞行為,對于認(rèn)識硒的生物地球化學(xué)循環(huán)過程及其對海洋生態(tài)系統(tǒng)的影響尤為重要。本論文針對長江口、東海和黃海桑溝灣(養(yǎng)殖海灣)開展了多次野外觀測,基于不同價(jià)態(tài)硒的濃度和硒同位素組成,系統(tǒng)地認(rèn)識了研究區(qū)域內(nèi)溶解態(tài)硒的時(shí)空分布格局和遷移轉(zhuǎn)化規(guī)律,以及硒沿食物鏈的傳遞行為特征,初步探討了我國近海硒的生物地球化學(xué)循環(huán)過程。硒穩(wěn)定同位素的分餾效應(yīng)大,是一種潛在的地球化學(xué)示蹤劑,但是目前海水中的硒同位素組成尚未見報(bào)道。本論文采用新型巰基樹脂預(yù)富集和純化海水樣品,將氫化物發(fā)生技術(shù)結(jié)合去溶劑裝置與多接收電感耦合等離子體質(zhì)譜儀聯(lián)用,建立了海水中溶解態(tài)硒同位素組成的分析方法。δ82/78Se、δ82/77Se和δ82/76Se的長期精密度分別為0.07‰、0.10‰和0.16‰(2sd,n=24),優(yōu)于文獻(xiàn)報(bào)道值,多個(gè)硒標(biāo)準(zhǔn)溶液的測定結(jié)果與國際同行接近(p=0.4),而且加標(biāo)海水經(jīng)巰基樹脂分離前后也無明顯的硒同位素分餾。在長江口,夏季(2011年7月)和春季(2012年3月)的溶解態(tài)無機(jī)硒(Dissolved Inorganic Selenium,DISe = Se(Ⅳ)+Se(Ⅵ))濃度范圍分別為 0.35～4.39 nmol/L和0.49～4.75nmol/L,其中Se(Ⅵ)為溶解態(tài)無機(jī)硒的主要存在形態(tài)。DISe濃度水平分布格局呈現(xiàn)口內(nèi)向口外逐漸降低的特點(diǎn),受長江淡水、臺灣暖流和黃海沿岸流三個(gè)水團(tuán)的共同控制,各水團(tuán)皆具有特征性的Se(Ⅳ)/Se(Ⅵ)比值。冬季時(shí)DISe、Se(Ⅳ)和Se(Ⅵ)呈嚴(yán)格的保守性行為,而夏季時(shí)則呈非保守性行為。在咸淡水混合的基礎(chǔ)上,浮游植物利用和懸浮顆粒物吸附是長江口 DISe被清除的主要原因,而且Se(Ⅳ)被清除的程度大于Se(Ⅵ)。東海陸架夏季(2013 年 8 月)的δ82/76DISe 平均值為 0.82‰(-1.14‰～1.66‰),是全球第一組海水中溶解態(tài)硒同位素?cái)?shù)據(jù)。春季(2011年5月)和夏季(2013年8月)DISe濃度范圍分別為0.30～2.3 nmol/L和0.26～2.2 nmol/L,較為接近,其中Se(Ⅵ)為溶解態(tài)無機(jī)硒的主要存在價(jià)態(tài)。DISe濃度分布受到長江沖淡水、臺灣暖流和黑潮水的共同控制,呈現(xiàn)近岸高、離岸逐漸降低的特點(diǎn)。初步收支估算顯示臺灣暖流和黑潮水入侵陸架是東海DISe的重要來源,共計(jì)輸入約90%的DISe。沖繩海槽區(qū)域的δ82/76DISe值隨水深從1.59‰逐漸降低至0.41‰,真光層內(nèi)輕質(zhì)硒同位素被浮游植物優(yōu)先利用,導(dǎo)致水體δ82/76DISe偏重,而深層水體生源有機(jī)質(zhì)降解,輕質(zhì)同位素被優(yōu)先釋放到水體中,是δ82/76DISe值逐漸偏輕的可能機(jī)制。長江口近底層缺氧水體中82/76DISe值明顯偏負(fù)(-0.66‰),偏輕約1‰t～2‰,可能發(fā)生了微生物異化還原Se(Ⅵ)。在黃海桑溝灣,2013年的3次調(diào)查(4月、7月和10月)發(fā)現(xiàn)表層水體中DISe濃度范圍為0.21～1.36nmol/L,其中Se(Ⅵ)為溶解態(tài)無機(jī)硒的主要存在形態(tài)。DISe和Se(Ⅳ)濃度存在明顯的季節(jié)差異,夏季低而春、秋季高,而且受灣內(nèi)大面積密集養(yǎng)殖藻類和貝類以及浮游生物的影響,還呈現(xiàn)出明顯的水平梯度變化特點(diǎn)。初步估算了桑溝灣內(nèi)DISe的收支模型,表明最主要的源是黃海與桑溝灣的水交換,其次是地下水輸入;而最重要的匯是生物移除,共計(jì)移除約53±12%的DISe。桑溝灣2015年5月表層水體中溶解態(tài)總硒(Total Dissolved Selenium)同位素組成(TDSe=DOSe+DISe,DOSe 為溶解態(tài)有機(jī)硒,Dissolved Organic Selenium)的范圍為0.38‰到1.06‰,其中δ82/76DISe值相對偏負(fù)(-2.77‰到-2.05‰)。灣內(nèi)生物的硒同位素組成范圍較寬(-3.26到3.46‰),其平均δ82/76Se值的順序?yàn)?魚類肌肉(-1.11±2.02‰)浮游動(dòng)物(0.76±0.17‰)≈浮游植物(0.80±0.10‰)牡蠣肌肉(1.24±0.30‰)扇貝肌肉(1.67±0.23‰)龍須菜(1.88±0.21‰)海帶(3.19±0.22‰)。若不考慮人為餌料等的影響,桑溝灣灣內(nèi),相較于水體中的溶解態(tài)無機(jī)硒,浮游植物和大型藻類均明顯富集重質(zhì)硒同位素;灣內(nèi)貝類與懸浮顆粒物和浮游植物相比,富集重質(zhì)硒同位素;魚類的δ82/76Se值隨著硒含量、δ15N值增加而增加,逐漸富集重質(zhì)硒同位素。本論文針對我國長江口、東海陸架和黃海桑溝灣內(nèi)硒濃度和同位素組成的研究成果表明,我國近海區(qū)域溶解態(tài)硒受水團(tuán)混合、生物利用、懸浮顆粒物吸附和氧化還原環(huán)境變化等多種因素控制,而且硒同位素沿食物鏈傳遞時(shí)會產(chǎn)生明顯的同位素分餾,為硒同位素成為有效的地球化學(xué)示蹤因子提供了依據(jù)。
[Abstract]:Trace elements play an important role in the marine ecosystem, is the focus of research in the field of marine science and global environmental change, but also a frontier field of traditional non stable isotope is also the isotope research. Many biological selenium is required, the high concentration would produce toxic effects, but also along the food chain enrichment Study on the distribution of selenium in the ocean. And along the transfer behavior of the food chain, is particularly important for the biogeochemical cycle of selenium and its impact on the marine ecosystem. Aiming at the mouth of the Yangtze River, the East China Sea and the Yellow Sea in Sanggou Bay (Bay aquaculture) to carry out a number of field observations, the concentration and composition of different valence selenium isotopes se based on the systematic understanding of the temporal and spatial patterns of migration and transformation rules of the distribution of dissolved selenium and selenium in the region, along the food chain transfer line features And discussed the biogeochemical cycle in coastal waters of China. The selenium fractionation effect of selenium isotopes, is a potential geochemical tracer, but the selenium isotopic composition of ocean water has not been reported. This paper adopts novel sulfhydryl resin preconcentration and purification of seawater samples, will combine to device and solvent multi collector inductively coupled plasma mass spectrometry combined with hydride generation technique, an analytical method of dissolved selenium isotopic composition in seawater. The delta 82/78Se, Delta 82/77Se and delta 82/76Se of the long-term precision of 0.07 per thousand respectively, 0.10 per thousand and 0.16 per thousand (2sd, n=24), better than the reported values, the determination results of multiple selenium the standard solution and close to the international counterparts (p=0.4), and the spiked seawater before and after sulfhydryl resin separation has no obvious. Selenium isotope fractionation in the Yangtze River Estuary, the summer (July 2011) and spring (March 2012) dissolved The inorganic selenium (Dissolved Inorganic Selenium, DISe = Se (IV) +Se (VI)) concentration range was 0.35 ~ 4.39 nmol/L and 0.49 ~ 4.75nmol/L, including Se (VI) is the main form of.DISe concentration distribution pattern appeared to the outside mouth gradually reduced characteristics of dissolved inorganic selenium, the Yangtze River water, common control of the Taiwan warm current and the Yellow Sea coastal water flow, the water masses are the characteristics of the Se (IV) /Se (VI) ratio. In the winter of DISe, Se (IV) and Se (VI) is strictly conservative behavior, while the summer is a non conservative behavior. On the basis of mixed salt and fresh water the use of phytoplankton and suspended particles, adsorption is the main reason for the mouth of the Yangtze River DISe is cleared, and the Se (IV) removed is greater than that of Se (VI). The East China Sea shelf in summer (August 2013) of the delta 82/76DISe average value of 0.82 per thousand (-1.14% ~ 1.66 per thousand), is the world's first group in seawater Dissolved selenium isotope data. In spring (May 2011) and summer (August 2013) DISe concentration range was 0.30 ~ 2.3 nmol/L and 0.26 ~ 2.2 nmol/L, which is close to that of Se (VI) for dissolved inorganic selenium mainly has the valence of.DISe concentration distribution by the Changjiang River, the common control of Taiwan warm current and the Kuroshio. Present, coastal, offshore characteristics gradually reduced. Preliminary estimates indicate that the balance of Taiwan warm current and the Kuroshio the continental shelf is an important source of DISe in the East China Sea, about 90% of the total input of 82/76DISe. DISe. in the Okinawa trough area value with depth from 1.59 per thousand gradually reduced to 0.41 per thousand, within the euphotic zone light selenium isotope by phytoplankton is preferred use, resulting in water and deep water on the delta 82/76DISe, biogenic organic matter degradation, light isotope is preferentially released into water, 82/76DISe values is small. The possible mechanism gradually in the Changjiang Estuary near the bottom of. 82/76DISe oxygen in water was significantly negative (-0.66%), partial light about 1 ~ 2 T%%, possible microbial dissimilatory reduction of Se (VI) in the Yellow Sea. In Sanggou Bay, 3 2013 Survey (April, July and October) found the concentration of DISe in surface water is 0.21 ~ 1.36nmol/L. The Se (VI) is the main form of.DISe and Se dissolved inorganic selenium (IV) concentration varied with season, summer is low and high in autumn and spring, but also by the large area of intensive farming algae and plankton and shellfish, also showing a level gradient characteristic. Budget model of mulberry the DISe ditch was preliminarily estimated that the main source of the Yellow Sea and the Sanggou Bay water exchange, followed by the groundwater input; and the most important biological sinks is removed, total dissolved removed about 53 + 12% DISe. in Sanggou Bay in May 2015 in the surface waters of total selenium (Total Dissolved Seleniu M (TDSe=DOSe+DISe, DOSe) isotopic composition of dissolved organic selenium, Dissolved Organic Selenium) in the range of 0.38 per thousand to 1.06 per thousand, the 82/76DISe values of relative partial negative (-2.77% to -2.05%). The biological selenium isotope composition of a wide range (-3.26 to 3.46 per thousand), the average 82/76Se values. Order: fish muscle (-1.11% + 2.02 (0.76 + 0.17) planktonic animal%) = phytoplankton (0.80 + 0.10 per thousand (1.24 + 0.30) oyster muscle muscle Scallop in Shell%) (1.67 + 0.23 per thousand (1.88 + 0.21)%) of Gracilaria kelp (3.19 + 0.22 per thousand). Without considering the effect of artificial bait the Sanggou Bay Bay, dissolved inorganic selenium compared to water, phytoplankton and macroalgae were significantly enriched in heavy isotopes of selenium; the shellfish and suspended particulate and phytoplankton in heavy enriched selenium isotope; Delta 82/76Se fish value with the Se content, 15N values increased gradually. The enrichment of heavy isotopes of selenium gradually in our country. This paper research the mouth of the Yangtze River, the East China Sea shelf and the Yellow Sea Bay and Sanggou selenium isotopic composition indicate that dissolved selenium coastal region of our country by water mixing biological utilization, suspended particle adsorption and redox environment of many factors such as control, and selenium isotope along the food chain will produce significant isotopic fractionation, provide the basis for the effective factors of geochemical trace selenium isotopes become.

【學(xué)位授予單位】：華東師范大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：P736.4

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