【作者】 李莉；

【导师】 杨桂朋；

【作者基本信息】 中国海洋大学 ， 海洋化学， 2014， 博士

【摘要】 挥发性卤代烃（Volatile halocarbons，简称VHCs）是大气中受关注度较高的痕量气体，既有温室效应又能与平流层中的臭氧发生化学反应，大部分VHCs还具有一定的毒副作用。因此，VHCs在全球气候变化和生态环境等方面起着非常重要的作用。大气中VHCs的来源主要有天然源和人为源。众多的研究结果表明，海洋可能是大气中VHCs的重要的天然源，也可能是其汇。占全球71%的海洋对大气中VHCs的源和汇的平衡起着举足轻重的作用，海气界面层是VHCs气体交换的重要场所之一。因此，开展对海水中VHCs的分析和分布研究具有重要的学术意义。本论文以中国近海（东海、黄海和渤海）以及胶州湾作为研究目标，研究了7种VHCs浓度的分布及其影响因素；计算了氯甲烷、溴甲烷、四氯化碳和1,1,1-三氯乙烷的海-气通量及其饱和异常值；并且粗略估算了中国近海的释放对全球海洋释放的贡献。经过仔细的分析、归纳和总结，本论文得到如下结论。（1）于2009年11月18日-12月25日对黄海及长江口周边海域的VHCs的浓度分布和5种VHCs的海气通量进行了研究。结果表明：溴甲烷、二氯乙烯、氯仿、三氯乙烷、四氯化碳和三氯乙烯的浓度范围为0.24~10.22、1.11~15.8、0.67~49.22、1.59~14.46、1.31~6.34和5.59~71.68pmol/L，平均浓度为1.57、4.14、8.44、4.59、3.54和19.30pmol/L。VHCs的浓度受黄海环流和东海环流的影响，且部分VHCs的浓度可能与浮游生物的活动有关。北黄海中VHCs的分布没有明显的规律，部分河流入海口处浓度较高；南黄海中的VHCs的近岸浓度高于远海浓度；长江口区域高浓度的VHCs出现在河口外。溴甲烷、三氯乙烷和四氯化碳的饱和异常值范围分别为-96.34~584.99%、74.77~1987.11%和-75.99~10.30%，其平均饱和异常值分别为-0.62%、436.78%和-39.22%。溴甲烷、四氯化碳、三氯乙烷、氯仿和三氯乙烯的通量范围为-16.76~38.55、-25.72~0.72、0.19~48.87、-174.79~153.50和0.72~154.92nmol m-2d-1，平均通量分别为-1.27、-6.01、9.75、-33.24和36.88nmol m-2d-1。11-12月（秋末）的黄海和长江口调查海域是溴甲烷、四氯化碳和氯仿的汇，是三氯乙烯和三氯乙烷的源。海气通量的大小与风速和VHCs的海气间的浓度梯度有关。（2）于2010年9月对黄海和渤海7种VHCs的浓度分布和4种VHCs海气通量进行了研究。研究结果表明：氯甲烷、溴甲烷、二氯乙烯、氯仿、三氯乙烷、四氯化碳和三氯乙烯的浓度范围为51.69~156.26、1.14~4.34、5.15~18.79、3.79~124.43、0.35~7.82、1.17~11.61和5.63~43.39pmol/L，平均浓度分别为89.87、2.34、12.12、28.31、5.49、2.99和25.07pmol/L。VHCs在北黄海和渤海的分布规律很不明显，渤海VHCs的最低浓度一般位于人为影响较小的中部海域；南黄海沿岸的VHCs的浓度较高。溴甲烷、氯甲烷、四氯化碳和三氯乙烷的饱和异常值范围为-27.61~185.69%、-29.31~125.66%、-69.43~263.22%和-76.25~463.04%，其平均值分别为46.85%、25.65%、-16.85%和296.72%。由于复杂的水文条件和环境因素的影响，VHCs饱和异常值的变化趋势并不一致。海气通量计算结果表明氯甲烷、溴甲烷、四氯化碳和三氯乙烷的海气通量的范围为-71.94~266.05、-3.67~11.80、-13.38~16.77和-0.15~52.96nmol m-2d-1，其平均通量为27.28、1.36、-0.61和12.86nmol m-2d-1。氯甲烷、溴甲烷、四氯化碳和三氯乙烷全年通量（黄渤海）分别是0.19、0.018、-0.013和0.24Gg/y。计算结果表明，9月的黄海和渤海调查海区是四氯化碳的汇，是氯甲烷、溴甲烷和三氯乙烷的源。海气通量的大小与表层水中VHCs的浓度、水温和风速有关。溴甲烷和三氯乙烷的通量变化与饱和异常值的变化趋势类似。（3）于2010年6月对东海7种VHCs的浓度分布和4种物质的海气通量进行了研究，结果表明氯甲烷、溴甲烷、二氯乙烯、三氯乙烯、氯仿、四氯化碳和三氯乙烷的浓度范围为49.37~105.72、1.31~13.80、5.11~11.21、5.51~25.25、9.26~23.71、0.71~15.55和1.31~14.89pmol/L，平均浓度分别为为80.46、4.12、9.06、12.89、17.98、7.71和9.39pmol/L。在沿岸流、东海环流、长江冲淡水以及生物活动等的综合作用下，VHCs在长江口和近岸的浓度较高（除三氯乙烯以外），近岸向外海浓度逐渐减少。氯甲烷、溴甲烷、四氯化碳和三氯乙烷的饱和异常值的范围是-34.22~43.33%、-41.51~431.89%、-32.51~269.19%和-15.78~846.54%，平均异常值分别为8.47%、65.63%、99.72%和511.29%。计算结果表明6月东海VHCs均处于过饱和状态。海气通量计算结果表明氯甲烷、溴甲烷、四氯化碳和三氯乙烷的海气通量的范围为-88.10~174.10、-5.08~60.59、-2.71~68.23和-0.85~78.22nmol m-2d-1，其平均通量分别为29.48、7.42、14.70和29.56nmol m-2d-1。6月的东海是这4种VHCs的源。海气通量的大小与风速、温度、海气界面的浓度梯度等共同决定。（4）通过2010年3月至2011年2月对胶州湾的调查，获得了胶州湾表层海水中VHCs的浓度分布及季节变化规律。由于海水的潮汐运动、陆地径流、海水养殖和水上运输等的影响，VHCs的分布趋势并不一致。一般表现为在东部近岸河口处的浓度较高，北部浓度较高，中部和湾口浓度较低。胶州湾表层海水中VHCs有明显的季节变化，但不同物质的变化趋势并不一致，冬季氯甲烷的浓度最高，溴甲烷的最高浓度在秋季，四氯化碳和三氯乙烯在夏季的浓度最高，二氯乙烯、氯仿和三氯乙烷的浓度在春季最高，在秋季最低。VHCs的季节变化可能与水温、陆地径流的大小和生物的活动等有关。VHCs的海气通量也具有明显的季节变化，计算结果表明胶州湾是VHCs的源，海气通量的大小与温度、浓度和风速有关。尽管胶州湾VHCs的浓度高于外海的浓度，但是胶州湾的风速和温度较低，以致胶州湾的月平均海气通量稍高于外海的调查结果，8月VHCs（氯甲烷除外）月平均通量甚至低于东海（6月）的海气通量结果。胶州湾的面积小，因此胶州湾的海气通量对局部海域的贡献较大，但对中国近海的贡献很小。（5）本文调查中均未发现VHCs的浓度及其饱和异常值与环境因素之间、不同的VHCs之间存在明显的相关性。即便是利用四氯化碳的饱和异常值对VHCs的饱和异常值进行热力学校正后，也未发现VHCs的饱和异常值与环境因素之间存在明显的相关关系。这也表明VHCs的来源比较复杂，既有人为源又有天然源；由于VHCs浓度的影响因子较多，如温度、Chl-a、细菌、海水的运动、近岸释放等，难以推知它们各自的影响强度。（6）经过简单外推后，氯甲烷、溴甲烷、四氯化碳和三氯乙烷的年海气通量（东海、黄海和渤海）分别为0.60、0.22、0.62和1.33Gg/y。占全球海洋面积的0.33%的中国近海的释放约占全球海洋释放量的0.09%、0.39%、4.43%和0.19%，中国近海的氯甲烷和三氯乙烷的释放量较低。更多还原

【Abstract】 Volatile halocarbons (VHCs) are significiant trace gases in the atmosphere,which are part of greenhouse gases and ozone depleting substances and take importantroles in global climatic change and environment change. The VHCs in the atmosphereare mainly from natural production and anthropogenic activities. Previous researcheshave showed that the ocean may be the source or sink of VHCs. Ocean, whichoccupies the71percents of the Earth’s area, takes an important and complex role inthe biological balance of the atmospheric VHCs. Marine boundary layer is animportant field in which the gases in water exchange with those in the atmosphere,thus, it is important to investigate the distributions of the VHCs in sea surfaceseawater.In the present dissertation, the East China Sea (ECS), the Yellow Sea (YS), theBohai Sea (BS) and the Jiaozhou Bay (JZB) are investigated. The distributions,saturation anomalies (SA) and sea-to-air fluxes of the VHCs are analysised anddiscussed systematically. The main research conclusions are drawn as follows:(1) The results showed that the concentrations for CH3Br, C2H2Cl2, CHCl3,CH3CCl3, CCl4and C2HCl3in surface water were0.24~10.22,1.11~15.8,0.67~49.22,1.59~14.46,1.31~6.34and5.59~71.68pmol/L, respectively, with theaverage concentrations of1.57,4.14,8.44,4.59,3.54and19.30pmol/L, in the YS andthe Yangtze River Estuary (YRE) during Nov-Dec2009. The individual VHCs hadtheir own distribution patterns in this survey area, because that the concentrations ofVHCs were influenced by the Yellow Sea circulation, the East Sea circulation andbiological activities et al. The highest concentrations of VHCs in the Northern YellowSea (NYS) usually were observed in the coastal area in which the river current flowedinto sea, the highest concentrations of VHCs were observed outer the Yangtze estuaryin the YRE, and the concentrations for VHCs decreased from inshore to offshore in the Southern Yellow Sea (SYS). The results showed that the SA of CH3Br, CCl4andC2H3Cl3were-96.34~645.52%,74.77~1987.11%and-75.99~10.30%,respectively, with the average values of9.32%,436.78%and-39.22%. The sea-to-airfluxes of VHCs were computed as Wanninkhof relationship (Wan92) and two-layermodel theory. The results showed that fluxes of CH3Br, CCl4, C2H3Cl3, CHCl3andC2HCl3were-16.76~38.55,-25.72~0.72,0.19~48.87,-174.79~153.50and0.72~154.92nmol m-2d-1, respectively, with the average fluxes of-1.27,-6.01,9.75,-33.24and36.88nmol m-2d-1. These results demonstrated that the study area was the sourceof CH3Br, CCl4and CHCl3, and the sink of C2H3Cl3and C2HCl3. The fluxes of VHCswere influenced by the wind speed in situ and the difference concentrations in air andthose in seawater.（2）The concentrations of7kinds of VHCs, the fluxes and the SAof4kinds ofVHCs were investigated in BS and YS during Sept,2010. The results showed that theconcentrations of CH3Cl, CH3Br, C2H2Cl2, CHCl3, C2H3Cl3, CCl4, C2HCl3were51.69~156.26,1.14~4.34,5.15~18.79,3.79~124.43,0.35~7.82,1.17~11.61and5.63~43.39pmol/L, the average concentrations of them were89.87,2.34,12.12,28.31,5.49,2.99and25.07pmol/L, respectively. In general, the lowest concentrations ofVHCs were observed in the middle of BS with little anthropogenic influences, thehighest concentrations of VHCs were observed in the coastal of SYS. The SA ofCH3Br, CH3Cl, CCl4and C2H3Cl3were-27.61~185.69%,-29.31~125.66%,-69.43~263.22%and-76.25~463.04%, the average of them were46.85%,25.65%,-16.85%and296.72%. The VHCs SA had their own distribution pattern, due to thecomplexity hydrological conditions and environmental factors. The fluxes of CH3Cl,CH3Br, CCl4and C2H3Cl3were-71.94~266.05,-3.67~11.80,-13.38~16.77and-0.15~52.96nmol m-2d-1, the average of them were27.28,1.36、-0.61and12.86nmol m-2d-1. Therefore, the BS and YS was the source for CH3Cl, CH3Br andC2H3Cl3, and the sink for CCl4. The fluxes of VHCs were influenced by theconcentrations of VHCs, in situ wind speed and water temperature. The fluxes ofVHCs had similar distribution patterns with the SA of VHCs.(3) The concentrations of7kinds of VHCs, the fluxes and the SA of4kinds of VHCs were investigated in ECS during Jun,2010. The results showed that theconcentrations of CH3Cl, CH3Br, C2H2Cl2, C2HCl3, CHCl3, CCl4and C2H3Cl3were49.37~105.72,1.31~13.80,5.11~11.21,5.51~25.25,9.26~23.71,0.71~15.55and1.31~14.89pmol/L, the average concentrations of them were80.46,4.12,9.06,12.89,17.98,7.71and9.39pmol/L. It was the coastal current, seawater circulation,Yangtze River diluted and biological activities that all influenced the VHCsconcentrations in this survey area. The concentrations of VHCs (C2HCl3exclude)exhibited the declining from the coastal to the open sea. The SA of CH3Cl, CH3Br,CCl4and C2H3Cl3were-34.22~43.33%,-41.51~431.89%,-32.51~269.19%and-15.78~846.54%, the average of them were8.47%,65.63%,99.72%and511.29%,respectively. The fluxes of CH3Cl, CH3Br, CCl4and C2H3Cl3were-88.10~174.10,-5.08~60.59,-2.71~68.23and-0.85~78.22nmol m-2d-1, the average of them were29.48,7.42,14.70and29.56nmol m-2d-1, respectively. Therefore, the ECS were thesource to4kinds of VHCs, and in the ECS surface water VHCs were super saturationduring the survey time. The fluxes of VHCs had related with the in situ wind speed,temperature of surface water, and the difference concentrations of VHCs in water andair.(4) The concentrations of7kinds of VHCs, the fluxes of4kinds of VHCs wereinvestigated in JZB from Apr,2010to Feb,2011. The results showed that each VHCshad its own distribution pattern because that the tidal current, land runoff, sewagedischarge and marineculture et al. all co-influenced the concentrations of VHCs. Ingeneral, the highest concentrations of VHCs were observed in the east coastal and thenorth of JZB, while the lowest concentrations were observed in the middle of and themouth of JZB. The VHCs concentrations were significant variation with the season,but each of them had its own distribution pattern, such as the highest concentration ofCH3Cl and CH3Br were occurred in winter and autumn respectively, the highestconcentration of CCl4and C2HCl3were occurred in summer, the highest concentrationof C2H2Cl2, CHCl3and C2H3Cl3were occurred in spring. The fluxes of VHCs alsosignificant varied with the season. Although the concentrations of VHCs were higherthan the other survey, however, the wind speed and temperature were lower in the similarly month, thus, the average fluxes of VHCs in Sep, Dec and Nov were weakhigher than those in the other survey, the fluxes of VHCs (CH3Cl exclude) in Augustwere lower than those in ECS. The contributions of VHCs in the JZB were high to thelocal area release, but were very low to the China Sea release due to owning the smallarea.(5) There were no significant correlation between the concentrations of VHCsand environmental factors, the SA of VHCs and environmental factors, in VHCs, inthe SA of VHCs. No significant correlation was founded, even the SA of VHCs wererevised by the SA of CCl4. This indicted that VHCs had complexity sources includingnatural sources and anthropogenic sources. A lot of factors influenced the VHCsconcentrations, including surface temperature, Chl-a, bacteria, water current andcoastal release, et al., however, their influencing abilities were not deduced due toabsent factor.(6) The results showed that the annual fluxes of CH3Cl, CH3Br, CCl4andC2H3Cl3were0.60,0.22,0.62and1.33Gg/y in China Sea (ECS, YS and BS) bysimply extrapolation. The China Sea occupied0.33%of the world sea area, the CH3Cl,CH3Br, CCl4and C2H3Cl3release in the China Sea were0.09%,0.39%,4.43%and0.19%of world ocean release, respectively. This indicated that the release of CH3Cland C2H3Cl3were smaller in China Sea than in world ocean.更多还原