【摘要】：濱海地區(qū)地下水和海水的相互作用的研究是闡明該區(qū)域的地下水流動(dòng)和溶質(zhì)運(yùn)移規(guī)律、陸-海交界面通量交換機(jī)理和過(guò)程及其對(duì)海岸帶生態(tài)系統(tǒng)和生物多樣性的影響的關(guān)鍵。此外,地下水—海水相互作用為有關(guān)部門(mén)解決及防治濱海生態(tài)環(huán)境問(wèn)題提供可靠的依據(jù)。本文以大亞灣巽寮灣海域某沙質(zhì)海灘為研究對(duì)象,結(jié)合野外觀測(cè)的地下水頭、鹽度及部分營(yíng)養(yǎng)鹽數(shù)據(jù)及室內(nèi)外實(shí)驗(yàn),利用數(shù)值模擬軟件MARUN進(jìn)行了潮灘中地下水—海水相互作用的二維數(shù)值模擬研究,模型中加入了營(yíng)養(yǎng)鹽衰減常數(shù),考慮了營(yíng)養(yǎng)鹽在運(yùn)移過(guò)程中的降解損失和營(yíng)養(yǎng)鹽的海水邊界,定量評(píng)估了海底地下水排泄和地下淡水排泄量及其所攜帶的營(yíng)養(yǎng)鹽。野外觀測(cè)數(shù)據(jù)和數(shù)值模擬結(jié)果表明,該研究區(qū)域營(yíng)養(yǎng)鹽含量和鹽度表現(xiàn)出很強(qiáng)的負(fù)相關(guān),即鹽度高的地方,營(yíng)養(yǎng)鹽低,鹽度低的地方營(yíng)養(yǎng)鹽高。具體而言,潮間帶上部和下部表現(xiàn)為低鹽度、高營(yíng)養(yǎng)鹽,而潮間帶中部則為低營(yíng)養(yǎng)鹽、高鹽度。由此判斷該區(qū)域存在鹽度暈(USP)、咸淡水混合帶以及陸源淡水排泄通道(FDT)。該海域潮灘地下水中營(yíng)養(yǎng)鹽含量較高,無(wú)大型河流匯入,通過(guò)地下水向海域輸入營(yíng)養(yǎng)鹽為該海域營(yíng)養(yǎng)鹽的最主要來(lái)源。數(shù)值模擬結(jié)果表明,在一個(gè)大小潮周期內(nèi),該研究剖面單位長(zhǎng)度海岸線(xiàn)上海底地下水排泄量(SGD)為8.68m2/d,其中地下淡水排泄量(FSGD)為2.03 m2/d,占海底地下水排泄總量的23.4%;內(nèi)陸地下水淡水(FSGD)攜帶的無(wú)機(jī)氮通量為18.67 g/(d·m),而海底地下水排泄(SGD)攜帶的無(wú)機(jī)氮通量為14.39 g/(d·m),最終進(jìn)入海水中的無(wú)機(jī)氮為進(jìn)入含水層無(wú)機(jī)氮的77.1%,約有23%在運(yùn)移的過(guò)程中降解。在以往的研究中認(rèn)為潮下帶的海底地下水排泄是很小的,而數(shù)值模擬結(jié)果表明,本剖面潮下帶存在一定量的海底地下水排泄,為1.84 m2/d,約為整個(gè)剖面海底地下水排泄的21.2%。
[Abstract]:The study of the interaction between groundwater and sea water in coastal area is the key to clarify the law of groundwater flow and solute transport, the flux exchange mechanism and process of land-sea interface and its influence on coastal ecosystem and biodiversity. In addition, the groundwater-seawater interaction provides a reliable basis for the relevant departments to solve and prevent coastal ecological environment problems. In this paper, a sandy beach in Shunliao Bay, Daya Bay, is taken as the research object, and the field observation data of groundwater head, salinity and some nutrients are combined with indoor and outdoor experiments. A two-dimensional numerical simulation study on the interaction between groundwater and seawater in tidal flat was carried out by using the numerical simulation software MARUN. The attenuation constant of nutrient salt was added to the model, and the degradation loss of nutrient salt and the seawater boundary of nutrient salt were considered in the model. The discharge of undersea groundwater and the discharge of underground fresh water and the nutrients they carry are quantitatively evaluated. The results of field observation and numerical simulation show that there is a strong negative correlation between the nutrient content and salinity in the study area, that is, where the salinity is high, where the nutrient is low, where the salinity is low, the nutrient content is high. Specifically, the upper and lower intertidal zone showed low salinity and high salinity, while the middle intertidal zone showed low salinity and high salinity. It is concluded that there are salt halo (USP), salt and fresh water mixed zone and continental freshwater discharge channel (FDT). In the region. The nutrient content in the groundwater of the tidal flat in this area is high and there are no large rivers flowing in. The main source of nutrient salt in the sea area is the input of nutrients from the groundwater to the sea area. The numerical simulation results show that, in a large or small tidal period, The (SGD) of groundwater discharge on the unit length coastline of the study section is 8.68 m2 / d, of which the (FSGD) of underground fresh water is 2.03 m2 / d, accounting for 23.4g / d of the total discharge of undersea groundwater, and the inorganic nitrogen flux of freshwater (FSGD) in inland groundwater is 18.67 g / (d m), and that in the sea is 18.67 g / (d m),. The flux of inorganic nitrogen carried by (SGD) in the bottom groundwater is 14.39 g / (d m), and the inorganic nitrogen that enters the seawater is 77.1% of the inorganic nitrogen in the aquifer. About 23% of the inorganic nitrogen is degraded in the process of transport. The results of numerical simulation show that there is a certain amount of undersea groundwater discharge in the subtidal zone of this section, which is 1.84 m2 / d, which is about 21.2g / d of that of the whole section.
【學(xué)位授予單位】：中國(guó)地質(zhì)大學(xué)(北京)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：P641;P734

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