Tracing Submarine Groundwater Discharge into Jiaozhou Bay by radium isotopes

本文依托国家自然科学基金项目“多种方法研究胶州湾海底地下水排泄（41072174）”，采用天然镭同位素（224Ra和226Ra）作为示踪剂，探讨沉积物中镭的扩散和解吸规律，分析胶州湾及其周边水体中224Ra和226Ra的时空分布特征；用224Ra和226Ra比值估算水体的表观年龄；通过三端元混合模型和镭质量平衡模型，评价胶州湾海底地下水排泄（SGD）及其输送的营养盐通量。 通过沉积物室内培养实验，发现同一沉积物在不同盐度水体条件下，随着水体盐度的逐渐增加，224Ra、226Ra解吸活度呈增加趋势，说明盐度越高，沉积物越容易解吸释放Ra到水中。不同粒径沉积物在同一水环境条件下，粒径为125μm...This paper is supported by the project of using multi-methods research submarine groundwater discharge (SGD) in Jiaozhou Bay (41072174), which belongs to the National Natural Science Foundation of China. The purposes are using natural radium isotopes (224Ra and 226Ra) as a tracer to explore the diffusion and desorption of radium from sediment, and analyze spatial and temporal characteristics of 22...学位：理学博士院系专业：海洋与环境学院_海洋化学学号：2242009015325

The Estimation of Submarine Inputs of Groundwater to a Coastal Bay Using Radium Isotopes

福建省漳州市隆教湾海水中镭同位素的研究,目的是评价海底地下水排泄量。在2007年6月的航次中,垂直于岸线的9km剖面上布置15个站位,每个站位用潜水泵采集表层海水样60L于塑料桶中。水样运回实验室后,立即用装有锰纤维的PVC管以虹吸的方式富集水样中的镭同位素,水通过PVC管的流速小于300ml/min。224Ra活度用连续射气法测定,测完224Ra后密封7d以上,然后用直接射气法测定226Ra活度。224Ra和226Ra活度都呈现自岸向海逐渐降低的规律,表明扩散控制镭同位素的分布,由224Ra获得68.83km2d-1的扩散系数,同时226Ra形成-0.963dpm100l-1km-1的活度梯度。用扩散系数和活度梯度建立的226Ra的离岸通量为6.62×1011dpmkm-2d-1,这个通量一定是得到SGD输入的镭支持,从而获得隆教湾的海底地下水排泄量是3.03×109m3km-2d-1。该排泄量包括陆源地下淡水排泄量和再循环海水排泄量,绝大部分可能是再循环海水,有待进一步研究。This paper reports the results of initial research on radium isotopes of surface ocean waters in the Longjiao Bay on the western flank of Taiwan Strait. The main objective of this research is to assess the submarine groundwater discharge (SGD). In order to assess the spatial distribution of 224Ra and 226Ra, the authors collected 15 surface ocean water samples (ca. -1 m in depth) during the low tide. The collection was performed within a period of 2 hours in the direction from onshore to 9 km offshore by using 60 L polypropylene buckets. In the laboratory, the water samples were immediately treated through gravity-fed PVC column (4.5 cm in diameter, 50 cm in length), filled with manganese oxide-impregnated acrylic fiber at a flow rate of ~300 ml/min to retain radium. After that, the activities of 224Ra absorbed on the Mn-fiber were measured through the continuous emanation method. Finally, the Mn-fiber was sealed for more than 7 days, and the activities of 226Ra absorbed on the Mn-fiber were measured through the direct emanation method. 226Ra distribution yields an activity gradient of -0.963 dpm100 l-1km-1. The short-lived 224Ra distribution in this region yields an eddy diffusion coefficient of 68.83 km2d-1. The interpretation is that the eddy diffusion is the primary controlling agent for the shore perpendicular distribution of the long-lived 226Ra. In order to estimate the seepage rate of groundwater in the study area, the authors applied the approach developed by Moore. The short-lived radium isotopes, 224Ra, were used to establish the eddy diffusion coefficient for the near-shore study area. The product of the eddy diffusion coefficient and the offshore 226Ra activity gradient established the 226Ra flux of 6.62×1011dpmkm-2d-1. It is expected that this flux must be balanced by Ra input from the submarine groundwater discharge (SGD). On the basis of the flux of SGD within the shore, 226Ra budget was calculated as 3.03×109 m3km-2d-1. This magnitude of SGD includes terrestrially-derived fresh SGD and recirculated seawater SGD, However, further researches should be required to determine the terrestrially-derived fresh SGD on the one hand, and recirculated seawater SGD on the other hand.国家自然科学基金项目(编号:40672166)资

Estimating Submarine Groundwater Discharge into the Jiaozhou Bay Using ~(226)Ra

海底地下水排泄(SGD)是全球水循环的一个组成部分,其输送的溶解物质不仅参与海洋的生物地球化学循环,而且影响近岸海域的生态环境。为了评估胶州湾海底地下水排泄状况,通过建立胶州湾内海水中226Ra的质量平衡模型来计算海底地下水排泄通量。胶州湾海水中226Ra的源主要有河流的输入、沉积物扩散输入和地下水的输入,海水系统在稳定状态下,这几种源应该与湾内海水和湾外海水的混合损失达到平衡。除了将地下水输入作为未知项外,对其他源和汇逐个进行量化,计算得知:2011年9—10月胶州湾的海底地下水排泄通量为7.85×10~6m~3·d~(-1);2012年4—5月胶州湾的海底地下水排泄通量为4.72×106m~3·d~(-1)。在此基础上,对地下水输入胶州湾的营养盐进行了评价。Submarine groundwater discharge( SGD) is a part of global water cycle,which delivers a large amount of solutes to the biogeochemical cycle and affects the coastal ecological environment. The ~(226)Ra mass balance model was established to estimate the submarine groundwater discharge to the Jiaozhou Bay. The ~(226)Ra sources include river transport,sediment diffusion and SGD,these sources should be in balance with the mixing loss of the bay water and open seawater when the seawater system is in the stable state. Except for the SGD was unknown item,other sources and sinks were quantified one by one. Calculated results showed that the SGD fluxes during September to October in 2011 was 7. 85 × 106m~3·d~(-1),April to May in 2012 was 4. 72 × 106m~3·d~(- 1). Based on the SGD fluxes,the SGD derived nutrient fluxes were estimated.国家自然科学基金项目(41072174)~

Temporal and spatial variation of nutrients in the rivers around Jiaozhou Bay and its fluxes into the sea

本文选取胶州湾周边5条主要入海河流作为研究对象,于2011秋季和2012年春季,测定了河流中无机营养盐的浓度水平,调查了各河流营养盐的主要来源,分析了营养盐的时空变化及成因,并计算了营养盐的入海通量.结果表明,各流域nO-3-n、SIO2-3-SI、nH+4-n、nO-2-n浓度主要表现为秋季较高,PO3-4-P浓度春季较高.白沙河、洋河流域营养盐主要来源为面源污染;墨水河、李村河流域营养盐主要来源于工业废水和生活污水;大沽河流域营养盐主要来源于农田径流和生活污水.除nH+4-n入海通量为墨水河最高外,其余各项营养盐入海通量均为大沽河最高.dIn、PO3-4-P、SIO2-3-SI入海通量分别为373.74x103MOl·d-1、7.08x103MOl·d-1、73.16x103MOl·d-1,n∶P∶SI数量比约为53∶1∶10.River runoff is the most important discharge pathway from mainland to sea,which is one of the reasons that the eutrophication and red tide occur frequently in parts of Jiaozhou Bay.The nutrient investigations about five relatively big rivers around Jiaozhou Bay were conducted in autumn of 2011 and spring of 2012,respectively.We measured the nutrient concentrations in river water, investigated the main resources of nutrients,analyzed the temporal and spatial variations of nutrients and its causes, and calculated the nutrient fluxes to Jiaozhou Bay.Results show that the concentrations of NO-3-N, SiO2-3-Si, NH+ 4-N and NO-2-N are higher in autumn while the concentration of PO3-4-P is higher in spring.Non-point source pollution is the main source of nutrients in Baisha River and Yang River.Industrial wastewater,urban sewage and household wastes are the main sources of nutrient in Moshui River,and the nutrients originate mainly from farmland runoff and sewage in Dagu river.Except for NH+ 4-N flux which is much higher in Moshui River,all other nutrient fluxes to the sea are comparatively higher in Dagu River.The calculated fluxes for DIN,PO3-4-P and SiO2-3-Si are 373.74 × 103mol·d- 1,7.08 ×103mol·d- 1and 73.16 × 103mol·d- 1, respectively,and the ratio of N,P and Si within the fluxes is 53 ∶ 1 ∶ 10.国家自然科学基金项目资助(41072174)资

Characteristics of Radium Desorption from Sediments in the Salt Water Environment

海底沉积物向上覆水体扩散的镭是海洋水体中镭同位素的重要来源之一。为了研究沉积物中镭同位素的解吸和扩散特点,进行了不同盐度和不同粒度条件下224rA和226rA解吸的模拟实验,并通过多个时间段的沉积物培养实验获取224rA和226rA的扩散通量。实验结果表明:随着水体盐度增大,沉积物中224rA、226rA的解吸量随之增加,在盐度为25时,解吸量基本达到最大值;在同一咸水环境条件下,4个粒级(2000~1000μM、1000~500μM、500~250μM、250~125μM)的沉积物的224rA、226rA解吸量比较接近,粒级>2000μM的224rA、226rA解吸量略高于上述4个粒级,而粒级<125μM的224rA、226rA解吸量远大于上述5个粒级;胶州湾沉积物中224rA和226rA的平均扩散通量分别为0.85 bQ·M–2·d–1和0.022 bQ·M–2·d–1。Radium diffusion from sediments to overlying water is one of the important sources of radium isotopes in ocean water.A series of laboratory desorption/diffusion experiments were conducted to help elucidate the characteristics of sediments on 224 Ra and 226 Ra desorption and diffusion,which included 1) 224 Ra and 226 Ra desorption from sediments in water of different salinities,2) 224 Ra and 226 Ra desorption from sediments of different grain sizes in water of the same salinity,3) 224 Ra and 226 Ra diffusive fluxes by observing Ra enrichment with time in the overlying water of incubated sediments.The experimental results show that there is an increase in the amount of 224 Ra and 226 Ra with the increase of salinity from 5 to 30,and Ra desorption is strongest at the salinity of 25.Under the same salt water condition,224 Ra and 226 Ra desorption activities of the four grain sizes(2000~1000 μm,1000~500 μm,500~250 μm and 250~125 μm) of sediments are very close to each other.When the grain sizes of sediments are larger than 2000μm,the 224 Ra and 226 Ra desorption activities are slightly higher than those of the sediments of the above-mentioned four grain sizes.When the grain sizes of sediments are less than 125 μm,the 224 Ra and 226 Ra desorption activities are much larger than those of the above-mentioned five grain sizes.The average diffusive fluxes of 224 Ra and 226 Ra of sediments from Jiaozhou Bay are 0.85 Bq·m-2·d-1 and 0.022 Bq·m-2·d-1,respectively.国家自然科学基金项目(编号:41072174)资

The Evaluation of Submarine Groundwater Discharge in Jiaozhou Bay Based on ~(222)Rn Mass Balance

海底地下水排泄(Sgd)作为全球水循环的一个组成部分,近年来成为陆海相互作用的研究热点。地球化学示踪法是研究海底地下水排泄的主要手段。本文以环境同位素222rn作为示踪剂,通过构建222rn质量平衡模型来评价胶州湾的海底地下水排泄,并进一步估算地下水输入的营养盐。222rn质量平衡模型的源项考虑了河流的输入、沉积物的扩散、母体226rA的支持,汇项考虑了222rn的自身衰变、222rn散逸到大气的损失以及与湾外海水的混合损失,源汇项的差值则作为地下水输入的222rn通量。结果表明,2011年9—10月胶州湾海底地下水排泄通量为24.2 l？M–2？d–1,2012年4—5月胶州湾海底地下水排泄通量为7.8 l？M–2？d–1。丰水季节地下水输入胶州湾的营养盐低于河流输入的,但是枯水季节地下水输入的营养盐接近河流输入的,特别是输入的活性磷酸盐和硅酸盐很接近。Submarine groundwater discharge(SGD), an important part of global water cycle, has recently been a research focus in the field of land-ocean interaction along the coastal zone.Geochemical tracing is a major tool to study submarine groundwater discharge.Taking natural occurring isotope 222 Rn as a tracer, the authors built 222 Rn mass balance model to estimate groundwater discharge to Jiaozhou Bay, and also evaluated the nutrient fluxes transported via groundwater.River input, dispersion of sediments, and support from parent 226 Ra are considered to be the sources of 222 Rn mass balance model, whereas radioactive decay, escape from sea-water interface to air and loss in mixing with the low activity water from open ocean are considered to be the sink of the model.Thus, the imbalance of budget from the model is attributed to submarine groundwater discharge.Calculations show that submarine groundwater discharge flux to Jiaozhou Bay was 24.2 L·m–2·d–1 from September to October in 2011, and 7.8 L·m–2·d–1 from April to May in 2014, respectively.The results of the study also indicate that the nutrient fluxes derived from groundwater during the wet season are lower than those transported by the local rivers, whereas the nutrient fluxes derived from groundwater during the dry season are close to those transported by the local rivers and, what is more, soluble reactive phosphate and silicate fluxes from both groundwater and river are very close to each other.国家自然科学基金项目(编号:41072174)资

An Analysis of the Interaction between River Water, Groundwater and Seawater in Minjiang River Estuary Region, Fujian Province, Based on Stable Isotopes D and ~(18)O

为了揭示闽江河口两岸的地下水形成演化规律以及河口区河水、地下水和海水的相互作用,分别于2009年枯水期(10至11月)和2010年丰水期(7至8月),在闽江河口区采集了河水、地下水和海水样品,测定了水样的氢氧稳定同位素组成和盐度。研究结果表明:(1)闽江河口两岸的浅层地下水主要接受降水补给,北岸地下水还接受山区基岩裂隙水补给,南岸浅层地下水在枯水期还接受经过蒸发作用的灌溉水补给;(2)闽江河口区,枯、丰水期河水与地下水的补排关系始终表现为地下水补给河水,枯水期南岸地下水在河口混合中的贡献明显增大;(3)海岸带含水层基本上不存在海水入侵,仅局部含水层有微弱的海水入侵迹象;(4)丰水期和枯水期的淡咸水混合带在河口中的位置和混合类型存在明显差异。The aim of this study is to reveal the origin and evolution of groundwater as well as the interaction between groundwater, river water and seawater.During both the dry season (October and November) and the wet season (July and August) of 2009, the authors collected fresh river water and brackish water samples in Minjiang River estuary, groundwater samples near Minjiang River estuary, and seawater samples in Taiwan Strait, then measured salinity, D and 18 O isotopic composition for the water samples.Some conclusions have been reached: (1) the unconfined groundwater on both sides of Minjiang River estuary is mainly recharged by rainfall, the groundwater on the northern side is also recharged by the bedrock fissure groundwater, and the groundwater on the southern side is also recharged by the irrigation water in the dry season, which has somewhat experienced evaporation before discharging; (2) the interaction between river water and groundwater always shows that the groundwater recharges to the river water occur in both dry season and wet season, and the mixing ratio of groundwater from the southern side of Min River estuary significantly increases in the dry season; (3) the seawater intrusion in the costal aquifer doesn’t exist on the whole, and this kind of phenomenon just occurs locally in a small part of the costal aquifer; (4) the site and mixture type of the mixed zone between fresh and brackish water in the estuary in the dry season is clearly different from those in the wet season.福建省重点基金项目(编号:2009I0025); 国家自然科学基金项目(编号:41072174)联合资

Application of Radon and Radium Isotopes in Estimating Submarine Groundwater Discharge in Coastal Areas

海底地下水排泄(Sgd)是海岸带陆海相互作用的一个重要的过程,其重要意义体现在它对海岸带水循环和地球化学循环的影响,以及它对沿岸海域生态环境的影响。国际上自从20世纪90年代中期开始系统研究海底地下水排泄以来,已经研究和开发出一整套较为完善的理论和方法,但Sgd的研究在我国才刚刚起步,相关报道极少见且缺乏不同方法的对比研究。目前,评价Sgd常用的方法有:渗流仪法、数值模拟法和地球化学示踪法。其中以氡和镭为代表的地球化学示踪法成为最具影响力的评价方法。该文详细介绍用氡和镭同位素评价Sgd的理论和方法及其适用条件。Submarine groundwater discharge(SGD) is recognized as an important land-sea interaction in the coastal zone,for it is volumetrically and chemically significant to coastal water and chemical budgets,and it may have an influence on coastal ecological environment.Since the mid 90′s,a set of relatively complete theories and methods has been developed and established due to the systematic researches on SGD internationally.However the study on SGD has just begun in China,its relevant report is rarely available and short of comparison experiments of different methods.The current methods for SGD estimation mainly include: seepage meter measurement,numerical simulation,geochemical tracing method.Among those methods,geochemical tracing method has become one of the most powerful methods,and radium and radon as the representative of geochemical tracers has been extensively used.The methods and applicable conditions of SGD estimation using radon and radium isotopes are introduced in detail.近岸海域的海底地下水排泄及其海洋生态环境效应研究(编号40672166);多种方法研究胶州湾的海底地下水排泄(编号41072174

Distribution Feature of Trichlorofluoromethane and Its Chemical Tracer Study in the North Pole of Chukchi Sea

2008年7—9月于北极楚科奇海采集了17个站位不同深度的海水水样,用吹扫捕集与气相色谱相结合的方法分析氟氯烃CfC11(CCl3f)的含量分布,并结合温度、盐度、溶解氧等水文和海洋化学数据用于楚科奇海水的化学示踪研究.结果表明,楚科奇海表层水中CfC-11的含量在2.95--8.81 PMOl/kg之间,表层水与30 M层水还没完全混合;HEr-Ald浅滩南边为夏季太平洋入流水,而以北仍然为冬季陆架残留水;CfC-11高值进一步证实阿纳德尔水、白令海陆架水与阿拉斯加沿岸流在bArrOW峡谷混合,CfC-11低值则证实北极中层水增暖现象,CfC-11表层含量的显著增加表明楚科奇海陆坡区离岸较近的地方受到河流径流的影响.Seawater samples were collected at 17 stations in the Chukchi Sea from July to September in 2008,and CCl3F(CFC-11) was measured with gas chromatography coupled with a purge-trap concentrator system.The datas of CFC-11 were used for seawater tracer study together with temperature,salinity and DO.The results showed that the concentrations of CFC-11 in surface water were 2.95 pmol/kg to 8.81 pmol/kg,and the shallower than 30 m water had not commingle entirety,and to the south of the Herald Shoal was summer Pacific Ocean water,but to the north was winter Chukchi Sea residual water.High amount of CFC-11 confirmed that the Anadyr water,Bering sea shelf water and Alaska coastal current were mixed in the Barrow Canyon,and low amount of CFC-11 approved the phenomenon of warming of middle water in north pole,the markely increase of CFC-11 in surface water meant that the less distant offshore stations had great influence by river stream.国家自然科学基金(40276035

Assessment of submarine groundwater discharge into the Wuyuan bay via continuous Radon-222 measurements

海底地下水排泄(Sgd)近年来成为陆-海相互作用的研究热点,地球化学示踪方法是其主要研究手段,尝试用天然示踪剂氡-222评价厦门五缘湾的Sgd。为了评价五缘湾Sgd的入海通量及其变化,对五缘湾海水中222rn和226rA活度、大气中222rn活度、风速、水温和水深进行了连续2 d的测量,对沉积物进行了培养实验用以获得其222rn扩散通量和孔隙水中222rn活度。基于海水中222rn通量的质量平衡,对实测的海水中222rn活度实施了母体支持、涨落潮影响、大气逃逸损失、沉积物扩散输入、混合损失的校正,保守估计Sgd输入的222rn通量在0~126.7 bQ/(M2·H)范围内变化,对海水中222rn的平均贡献达54%。以井水和孔隙水中222rn的加权平均值作为Sgd端元的代表,获得Sgd的输入速率为0~29.3 CM/d,平均输入速率9.3 CM/d。Sgd输入速率的动态变化基本围绕12 H的周期波动,是对本海域正规半日潮的具体响应。假设Sgd以平均速率在五缘湾海底输入,则五缘湾海底的Sgd输入量为1.86x105M3/d。以陆源地下淡水占Sgd输入量的10%考虑,五缘湾的陆源地下淡水输入量约为1.86x104 M3/d。In recent years,submarine groundwater discharge(SGD) has been recognized as an important process in land-ocean interactions in the coastal zone(LOICZ).The subject has thus become the focus of intensive research.Geochemical tracers can be effective tools for estimating SGD in LOICZ.The objective of this study is to estimate SGD in the Wuyuan Bay using Radon-222(222Rn) as naturally occurring tracer.The dynamic variation of SGD can thus be subsequently assessed.We continuously measure the seawater 222Rn and 226Ra activities,the near-sea surface air 222Rn,wind speed,sea water temperature and depth for two consecutive days.We also deploy an incubation device to measure the diffusive flux of 222Rn from sediments and the pore-water 222Rn activities.Based on the mass balance principle for the 222Rn flux,the measured seawater 222Rn are corrected for the decay product of parent 226Ra,the effects of tides,the losses to the atmosphere,the diffusive influxes from the sediments,and the mixing with offshore seawaters.The result shows a conservative estimate of 222Rn flux attributed to SGD is between 0 and 126.7 Bq/(m2 h),which can account for 54% 222Rn in seawater.Taking a SGD end-member as example,the calculated SGD input rates range from 0 to 29.3 cm/d with an average value of 9.3 cm/d.The end-member is made of the weighted average of groundwater and pore-water 222Rn activities.The fluctuation in the SGD input rate has a 12-h period,which matches well with the semi-diurnal tides in this region.The SGD input to the Wuyuan Bay could be as much as 1.86×105 m3/d if the estimation were made under the assumption that the average SGD input rate is applicable to the entire bay area.The input of terrestrially derived fresh groundwater in the Wuyuan Bay could be approximately 1.86×104 m3/d if the fresh groundwater were 10% of the total SGD input.国家自然科学基金资助项目(40672166;41072174)---