夏季長江口外缺氧頻發(fā)的機(jī)制及酸化問題初探
發(fā)布時(shí)間：2018-11-10 12:28
【摘要】：針對夏季長江口外缺氧區(qū),深入認(rèn)識了同缺氧發(fā)生有著密切聯(lián)系的特殊海底地形、流場環(huán)境、鋒面和上升流等主要環(huán)境特征;特別地,夏季長江口外羽狀鋒和上升流這兩種物理過程是耦合在一起的,羽狀鋒的垂向分布形態(tài)與上升流具有密切的聯(lián)系.基于對夏季長江口外歷史缺氧事件的回顧與分析,從統(tǒng)計(jì)學(xué)意義上展現(xiàn)了缺氧區(qū)在水平分布上的空間結(jié)構(gòu),并認(rèn)識了缺氧發(fā)生區(qū)位置的細(xì)節(jié),發(fā)現(xiàn)口門外內(nèi)陸架區(qū)的溶解氧(DO)含量與水深之間呈"V"型關(guān)系,據(jù)此指出內(nèi)陸架的缺氧水體多發(fā)生在具有陡峭海底地形的坡面上.在長江口外缺氧機(jī)制現(xiàn)有認(rèn)知的基礎(chǔ)上,剖析了口門外陡坡地形何以能成為夏季缺氧核心頻發(fā)區(qū)的生物地球化學(xué)機(jī)制,闡釋了坡面處缺氧區(qū)位置與羽狀鋒面和上升流的內(nèi)在聯(lián)系.長江口外羽狀鋒和上升流及其耦合作用是誘發(fā)夏季缺氧的重要驅(qū)動(dòng)力,長江沖淡水羽狀鋒擴(kuò)展和上升流交互作用影響下營養(yǎng)鹽的持續(xù)輸送和該處良好的光照條件是夏季長江口外浮游植物繁殖和底層缺氧的重要機(jī)制.通過對缺氧區(qū)耗氧作用及有機(jī)碳礦化和營養(yǎng)鹽再生的探討,指出夏季長江口外顯著的耗氧過程亦主要發(fā)生在具有鋒面和上升流特征的陡峭坡面附近,并證實(shí)底層缺氧區(qū)存在營養(yǎng)鹽的表觀丟失現(xiàn)象;同時(shí),分析顯示長江口外泥質(zhì)區(qū)底邊界層中的沉積物再懸浮也可對有機(jī)碳耗氧礦化及營養(yǎng)鹽循環(huán)與再生產(chǎn)生影響.研究還指出長江口外的陡坡地形也是夏季低pH酸化環(huán)境的主要發(fā)生區(qū),陡坡處羽狀鋒面和上升流的耦合亦為誘發(fā)夏季底層酸化的重要物理驅(qū)動(dòng)力.最后,對今后長江口外缺氧區(qū)和水體酸化研究中予以關(guān)注的問題進(jìn)行了探討.
[Abstract]:In view of the anoxic zone outside the Changjiang Estuary in summer, the main environmental characteristics of the sea floor topography, flow field, front and upwelling which are closely related to the occurrence of hypoxia are deeply understood. In particular, the two physical processes, the plume front and upwelling, are coupled together in summer, and the vertical distribution of the plume front is closely related to the upwelling. Based on the review and analysis of the historical anoxia events outside the Changjiang Estuary in summer, the spatial structure of the horizontal distribution of the anoxic region is shown statistically, and the location of the anoxic region is recognized in detail. It is found that there is a "V" type relationship between dissolved oxygen (DO) content and water depth in the continental shelf area outside the mouth, and it is pointed out that the anoxic water body of the inland shelf mostly occurs on the slope with steep submarine topography. Based on the existing cognition of the mechanism of hypoxia outside the Changjiang Estuary, this paper analyzes the biogeochemical mechanism why the steep slope topography at the entrance of the Changjiang Estuary can become the core area of hypoxia in summer. The relationship between the position of anoxic zone on the slope and the pinnate front and upwelling is explained. The external plume front and upwelling in the Changjiang Estuary and their coupling are the important driving forces to induce anoxia in summer. The continuous transport of nutrients and good illumination conditions are the important mechanisms of phytoplankton propagation and hypoxia in the bottom layer of Yangtze River Estuary in summer under the influence of plume expansion and upwelling of Yangtze River Estuary. Based on the discussion of oxygen consumption, organic carbon mineralization and nutrient regeneration in the anoxic region, it is pointed out that the significant process of oxygen consumption outside the Changjiang Estuary in summer also mainly occurs near the steep slope with the characteristics of frontal and upwelling. The apparent loss of nutrients in the anoxic zone of the bottom layer was confirmed. At the same time, the analysis shows that the sediment resuspension in the bottom boundary layer of the outer muddy area of the Yangtze River Estuary can also affect the organic carbon oxygen consumption mineralization, nutrient cycling and regeneration. It is also pointed out that the topography of steep slope outside the Changjiang Estuary is also the main occurrence area of low pH acidification environment in summer, and the coupling between the plume front and upwelling at the steep slope is also an important physical driving force to induce the bottom acidification in summer. Finally, the problems concerned in the study of anoxic zone and water acidification outside the Changjiang Estuary are discussed.
【作者單位】： 中國海洋大學(xué)海洋化學(xué)理論與工程技術(shù)教育部重點(diǎn)實(shí)驗(yàn)室;國家海洋局第一海洋研究所;青島海洋科學(xué)與技術(shù)國家實(shí)驗(yàn)室海洋生態(tài)與環(huán)境科學(xué)功能實(shí)驗(yàn)室;國家海洋局第二海洋研究所海洋生態(tài)系統(tǒng)和生物地球化學(xué)重點(diǎn)實(shí)驗(yàn)室;
【基金】：國家自然科學(xué)基金項(xiàng)目(批準(zhǔn)號:41206068,41620104001) 國家自然科學(xué)基金委-山東省聯(lián)合基金項(xiàng)目(批準(zhǔn)號:U1406403) 中央級公益性科研院所基本科研業(yè)務(wù)費(fèi)專項(xiàng)資金(編號:2016G08) 青島海洋科學(xué)與技術(shù)國家實(shí)驗(yàn)室海洋生態(tài)與環(huán)境科學(xué)功能實(shí)驗(yàn)室開放基金(編號:KLMEES201603) 國家重點(diǎn)基礎(chǔ)研究發(fā)展計(jì)劃項(xiàng)目(編號:2010CB428703) 中國近海海洋綜合調(diào)查與評價(jià)專項(xiàng)(編號:908-ZC-I-03)資助
【分類號】：P734
本文編號：2322474
[Abstract]:In view of the anoxic zone outside the Changjiang Estuary in summer, the main environmental characteristics of the sea floor topography, flow field, front and upwelling which are closely related to the occurrence of hypoxia are deeply understood. In particular, the two physical processes, the plume front and upwelling, are coupled together in summer, and the vertical distribution of the plume front is closely related to the upwelling. Based on the review and analysis of the historical anoxia events outside the Changjiang Estuary in summer, the spatial structure of the horizontal distribution of the anoxic region is shown statistically, and the location of the anoxic region is recognized in detail. It is found that there is a "V" type relationship between dissolved oxygen (DO) content and water depth in the continental shelf area outside the mouth, and it is pointed out that the anoxic water body of the inland shelf mostly occurs on the slope with steep submarine topography. Based on the existing cognition of the mechanism of hypoxia outside the Changjiang Estuary, this paper analyzes the biogeochemical mechanism why the steep slope topography at the entrance of the Changjiang Estuary can become the core area of hypoxia in summer. The relationship between the position of anoxic zone on the slope and the pinnate front and upwelling is explained. The external plume front and upwelling in the Changjiang Estuary and their coupling are the important driving forces to induce anoxia in summer. The continuous transport of nutrients and good illumination conditions are the important mechanisms of phytoplankton propagation and hypoxia in the bottom layer of Yangtze River Estuary in summer under the influence of plume expansion and upwelling of Yangtze River Estuary. Based on the discussion of oxygen consumption, organic carbon mineralization and nutrient regeneration in the anoxic region, it is pointed out that the significant process of oxygen consumption outside the Changjiang Estuary in summer also mainly occurs near the steep slope with the characteristics of frontal and upwelling. The apparent loss of nutrients in the anoxic zone of the bottom layer was confirmed. At the same time, the analysis shows that the sediment resuspension in the bottom boundary layer of the outer muddy area of the Yangtze River Estuary can also affect the organic carbon oxygen consumption mineralization, nutrient cycling and regeneration. It is also pointed out that the topography of steep slope outside the Changjiang Estuary is also the main occurrence area of low pH acidification environment in summer, and the coupling between the plume front and upwelling at the steep slope is also an important physical driving force to induce the bottom acidification in summer. Finally, the problems concerned in the study of anoxic zone and water acidification outside the Changjiang Estuary are discussed.
【作者單位】： 中國海洋大學(xué)海洋化學(xué)理論與工程技術(shù)教育部重點(diǎn)實(shí)驗(yàn)室;國家海洋局第一海洋研究所;青島海洋科學(xué)與技術(shù)國家實(shí)驗(yàn)室海洋生態(tài)與環(huán)境科學(xué)功能實(shí)驗(yàn)室;國家海洋局第二海洋研究所海洋生態(tài)系統(tǒng)和生物地球化學(xué)重點(diǎn)實(shí)驗(yàn)室;
【基金】：國家自然科學(xué)基金項(xiàng)目(批準(zhǔn)號:41206068,41620104001) 國家自然科學(xué)基金委-山東省聯(lián)合基金項(xiàng)目(批準(zhǔn)號:U1406403) 中央級公益性科研院所基本科研業(yè)務(wù)費(fèi)專項(xiàng)資金(編號:2016G08) 青島海洋科學(xué)與技術(shù)國家實(shí)驗(yàn)室海洋生態(tài)與環(huán)境科學(xué)功能實(shí)驗(yàn)室開放基金(編號:KLMEES201603) 國家重點(diǎn)基礎(chǔ)研究發(fā)展計(jì)劃項(xiàng)目(編號:2010CB428703) 中國近海海洋綜合調(diào)查與評價(jià)專項(xiàng)(編號:908-ZC-I-03)資助
【分類號】：P734
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