本文關(guān)鍵詞： 鐳同位素 海底地下水排泄 海底地下淡水排泄 營養(yǎng)鹽 渦動擴散系數(shù) 大亞灣　出處：《中國地質(zhì)大學(北京)》2017年碩士論文　論文類型：學位論文

【摘要】：海底地下水排泄(SGD)是地下水與海水交換的研究重點,它包括了兩個部分,一部分是海底地下淡水排泄(SFGD),另一部分是再循環(huán)海水(RSGD)。作為水循環(huán)的重要組成部分,SGD是陸地輸入海洋化學物質(zhì)的重要通道之一,同時也是各種污染物質(zhì)輸入到海水中的一個隱蔽通道。近年來,已經(jīng)有許多的報道證明了由SGD驅(qū)動的物質(zhì)通量是不可被忽視的。本文以未被研究過SGD的大亞灣為研究對象,采集并分析了大亞灣區(qū)域的鐳同位素數(shù)據(jù),發(fā)現(xiàn)鐳同位素在海灣內(nèi)由東北部的子灣向西南灣口逐漸遞減。考慮了河流和外海影響,利用鐳同位素對水體刷新時間進行了估計,得到的結(jié)果是13.41~18.85 d,并利用納潮量模型(結(jié)果是18.83 d)驗證了鐳同位素的水體刷新時間估計。同時,我們利用水體表觀年齡模型得出水體表觀年齡是:9.35~26.72。三者結(jié)果基本一致,相互得到驗證。對于水體混合過程,我們根據(jù)~(224)Ra在海灣內(nèi)的分布狀況和一維~(224)Ra擴散模型,計算了大亞灣內(nèi)的水平渦動擴散系數(shù),結(jié)果為(7.80~11.65)×10~6cm2/s。同時,根據(jù)灣內(nèi)和灣口一個站點計算的垂直分布狀況,估算出垂直渦動擴散系數(shù)為(1.12~4.44)cm2/s。在估計水體刷新時間的基礎(chǔ)上,構(gòu)建了海灣內(nèi)的鐳同位素質(zhì)量平衡模型,估計出大亞灣內(nèi)SGD為(2.68~3.34)×10~7 m~3/d。通過耦合海灣內(nèi)水、鹽質(zhì)量平衡模型,估算出2015年7月大亞灣海底地下淡水排泄量為(3.98~7.12)×10~6 m~3/d。同時在年平均的意義上建立了穩(wěn)態(tài)區(qū)域水均衡模型,估算出海底地下淡水排泄為(1.23~2.41)×10~6m~3/d或(0.22~0.43)cm/d。兩個不同模型得出的海底地下淡水排泄量非常接近,結(jié)果得到相互驗證。估算了由SGD輸入到海灣的營養(yǎng)鹽與重金屬物質(zhì)通量。結(jié)果顯示由SGD輸入到海灣的重金屬通量明顯大于河水輸入,SGD驅(qū)動的營養(yǎng)鹽通量與河流輸入通量相當。確定了SGD攜帶化學物質(zhì)入海中所起的重要作用,在對海灣生態(tài)系統(tǒng)的研究中必須考慮SGD的影響。
[Abstract]:Submarine groundwater discharge (SGD) is the focus of research on the exchange of groundwater and seawater, which consists of two parts. One is the discharge of underwater fresh water, the other is the recycling of sea water, RSGD. As an important part of the water cycle, SGD is one of the important channels for terrestrial input of marine chemicals. In recent years, there have been many reports that the matter flux driven by SGD can not be ignored. In this paper, Daya Bay, which has not been studied on SGD, has been studied. The radium isotopic data in the Daya Bay area are collected and analyzed. It is found that the radium isotopes gradually decrease from Ziwan in the northeast to the mouth of the southwest bay in the Gulf. Considering the influence of rivers and the open sea, the refresh time of water body is estimated by using radium isotopes. The result obtained is 13.41 ~ 18.85 days, and the water refresh time estimate of radium isotope is verified by the model of tidal absorption (18.83 days). At the same time, the apparent age of water body is: 9.35 ~ 26.72 by using the water body apparent age model. The results are basically consistent with each other. For the mixing process of water body, we calculate the horizontal eddy diffusion coefficient in Daya Bay according to the distribution situation of Gui 224Ra in the bay and the one-dimensional diffusion model. The results show that the diffusion coefficient is 7.80 ~ 11.65) 脳 10 ~ (6) cm ~ (2 / s) 路s ~ (-1). At the same time, the horizontal vortex diffusion coefficient in Daya Bay is calculated. According to the vertical distribution calculated at a station in the bay and the mouth of the bay, the vertical eddy diffusion coefficient is estimated to be 1.124.44 cm ~ 2 / s. Based on the estimation of the water refresh time, a radium isotope mass balance model is established in the bay. The SGD in Daya Bay is estimated to be 2.68 ~ 3.34) 脳 10 ~ (7) m ~ (-1) 路d ~ (3 / d). By coupling the mass balance model of water and salt in the bay, it is estimated that in July 2015 the amount of underground fresh water discharged from the bottom of Daya Bay is 3.987.12) 脳 10 ~ (6) m ~ (3 / d) d. At the same time, a steady regional water balance model is established in the sense of annual average. It is estimated that the subsea freshwater discharge is 1.23 ~ 2.41) 脳 10 ~ (6) m ~ (-1) / d or 0.22 ~ 0.43 cm / d 路d. The two different models are very close to each other. The results show that the flux of nutrients and heavy metals from SGD to the bay is obviously larger than that from the river to the bay, and the flux of nutrient and heavy metal from the river to the bay is higher than that from the river. The flux is equivalent. The important role that SGD plays in carrying chemicals into the sea is determined. The effects of SGD must be considered in the study of the Gulf ecosystem.
【學位授予單位】：中國地質(zhì)大學(北京)
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：P734;X820;P641

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