共查询到19条相似文献，搜索用时 343 毫秒
1.
运用吹扫-捕集气相色谱法测定了2017年夏季长江口及其邻近海域海水中4种常见的挥发性卤代烃（VHCs,包括一氟三氯甲烷（CFC-11）、碘甲烷（CH3I）、三氯甲烷（CH3CCl3）和四氯乙烯（C2Cl4））以及大气中CFC-11、CH3I和C2Cl4的浓度。结果表明,表层海水中4种VHCs浓度的水平分布受长江径流输入影响强烈,整体上呈现近岸高、远海低的趋势。垂直方向上4种VHCs浓度最高值出现在10 m水层,长江口内断面的浓度整体高于口外断面的浓度。海水中VHCs的浓度分布受水文环境、生物释放和人为因素等的共同影响。相关性分析表明CH3I与Chl a浓度不存在明显的相关性,而CFC-11与CH3I、C2Cl4浓度存在显著相关性（P<0.01）,表明调查海域人为源对CH3I和C2Cl4的影响大于天然源。大气中CFC-11、CH3I和C2Cl4的浓度分布整体上呈现近岸高、远海低的趋势。CFC-11的浓度低于全球平均值,表明我国CFC-11的排放得到了有效控制。后向轨迹分析表明来自近岸的陆源污染物的扩散和输送是调查海域大气中3种VHCs的重要来源。CFC-11、CH3I和C2Cl4的海-气通量平均值分别为24.99 nmol/（m2·d）、7.80 nmol/（m2·d）、1.55 nmol/（m2·d）,表明夏季长江口及其邻近海域是大气中这3种VHCs的源。 相似文献
2.
海洋中产生的挥发性卤代烃(Volatile Halocarbons,VHCs)是氯、溴和碘进入大气的重要载体。海洋藻类能够产生损耗大气中臭氧的VHCs,尤其是海洋微藻已被证明是大气中一些VHCs的主要贡献者。环境因素对海洋微藻产生VHCs的影响研究较少,本文主要研究了光照和硝酸盐浓度对微藻释放VHCs的影响。将海洋微藻东海原甲藻(Prorocentrum donghaiense)和三角褐指藻(Phaeodactylum tricornutum)置于密封的玻璃容器中,并在不同光照条件(20 μmol/(m2·s)、70 μmol/(m2·s)和140 μmol/(m2·s))及不同硝酸盐浓度(1 mg/L、5 mg/L、10 mg/L和50 mg/L)下进行无菌单种培养,分析碘甲烷(CH3I)、二溴甲烷(CH2Br2)、一氯二溴甲烷(CHBr2Cl)和三氯乙烯(C2HCl3)4种VHCs的生产。采用吹扫?捕集气相色谱技术对其中的VHCs进行提取和分析。结果表明,光照强度和硝酸盐浓度会影响两种微藻对VHCs的释放,但是对不同VHCs的影响效果不同,其中CH3I的释放受光照强度和硝酸盐浓度变化的影响比较显著。一定范围内,光照强度越大,两种微藻对CH3I的释放量越大。适当的硝酸盐浓度(> 5 mg/L)在一定程度上促进了两种微藻对CH3I的释放。 相似文献
3.
海洋硫循环是全球硫循环重要的组成部分,而活跃于上层海洋的二甲基硫(DMS)是主要的生源硫化物,是现今国内外硫循环研究的热点之一。二甲基硫的生物、化学过程较为复杂,其在水体中的分布与浮游植物、浮游动物、细菌等生物因素以及光照、营养盐等环境因素密切相关。本文综述了与DMS循环有关的生物、化学循环过程及其参数化方案,包括细菌消耗、光化学氧化和海-气交换等。根据国内外研究进展,讨论了需要解决的问题,建立了东中国海DMS循环的概念模型。期望通过发展一个中国东部陆架海域物理-生物地球化学耦合三维生态动力学模式,获取DMS海气交换通量的时空分布,并定量评估中国东部陆架海域对全球大气温室效应的贡献。 相似文献
4.
挥发性卤代烃(VHCs)是大气中一类重要的挥发性有机污染物。本文于2020年9月对南海东北部及吕宋海峡邻近海域海水及大气中的二氯二氟甲烷(CFC-12)、三氯氟甲烷(CFC-11)、溴甲烷(CH3Br)和碘甲烷(CH3I)的浓度进行了同步测量,探讨了4种VHCs浓度的水平分布及其影响因素,并估算了CH3Br和CH3I的海-气通量。结果表明,调查海域海水中CFC-12、CFC-11、CH3Br和CH3I的浓度平均值分别为(1.96±0.84)、(5.35±4.86)、(1.26±0.57)和(2.58±0.88)pmol·L-1。海水中CH3Br和CH3I的分布是生物生产释放、陆源输入和光化学等多种因素共同作用的结果。大气中CFC-12、CFC-11、CH3Br和CH3I的浓度平均值分别为(480.65±68.55)、(184.07±31.22)、(... 相似文献
5.
甲烷(CH4)是影响地球辐射平衡的主要温室气体,海洋是大气CH4的自然源,而陆架等近海是释放CH4的热点海域。于2021年4月、7月和10月对渤海进行了调查,以认识其分布特征并估算其海-气交换通量。春、夏和秋季表层海水CH4浓度分别为(4.56±2.60)、(8.31±4.01)和(4.99±1.31) nmol/L,夏季明显高于春秋季。CH4的垂直分布规律为底层普遍高于表层,不同站位的垂直分布空间差异较大。渤海CH4分布主要受河流输入、油气泄漏、生物活动以及沉积物-水界面交换等因素的影响,其中黄河向渤海输入CH4约为每月1.4×104～2.8×105mol,秋冬季沉积物-水界面CH4交换通量范围为–4.0～0.42μmol/(m2·d),表明秋冬季沉积物既可能是渤海水体CH4的源,也可能是其汇。春、夏和秋季渤海CH4海-气交换通量分别为(1.1±... 相似文献
6.
测定了2018年春季长江口及其邻近海域海水和大气中碘甲烷(Iodomethane,CH3I)、二溴甲烷(Dibromomethane,CH2Br2)和溴仿(Tribromomethane,CHBr3)的浓度,研究其在海水和大气中的浓度分布特征,探讨了环境因素对其源汇和浓度分布的影响。调查海域海水中CH3I、CH2Br2和CHBr3的浓度分别为(5.76±2.50)、(5.38±3.31)和(4.65±3.50)pmol·L-1,总体呈现出近岸高,远岸低的趋势。调查海域CH3I的浓度分布受浮游植物的影响显著;CH2Br2的分布是多种因素共同作用的结果,其中人为输入是影响CH2Br2浓度分布的重要因素之一;CHBr3的浓度分布受人为输入和浮游植物产生释放的共同影响。垂直方向上,海水上下混合比较均匀,受长江冲淡水和沉积物释放的影响,CH3I、CH2Br2和CHBr3在表层和底层都观测到浓度高值。大气中CH3I、CH2Br2和CHBr3浓度分别是(1.06±0.77)、(1.72±1.22)和(1.97±2.12)pptv,总体上呈现近岸高于远岸的趋势,人为排放、海-气交换和气团活动共同影响了大气中挥发性卤代烃(Volatile halocarbons,VHCs)的浓度分布,大气中的CH2Br2和CHBr3存在多种来源,不同来源之间CH2Br2和CHBr3排放比率存在较大差异。CH3I、CH2Br2和CHBr3的海-气通量分别为(50.21±45.47)、(-1.76±77.43)和(-37.65±87.07)nmol·(m2·d)-1,表明调查期间长江口及其邻近海域是CH3I的源,同时也是CHBr3和CH2Br2的汇。 相似文献
7.
8.
二甲基硫（DMS）是海洋排放的占优势地位的生源硫气体,其在大气中的氧化产物能够影响到环境酸化和世界的气候变化.因此, 测定海水中的DMS对于准确地评价其在全球硫循环所起的重要作用具有重要意义.本文中作者研究了海水中DMS的痕量分析技术.海水中的DMS首先采用气提-冷阱捕集技术进行预浓缩, 然后用带有火焰光度检测器的气相色谱（GC-FPD）进行分析.该方法的精确度在5%以内, 平均回收率为85.6% （82.8%-90.5%）, 最小检出限为0.15 ng S.β-二甲基巯基丙酸内盐（DMSP）的分析是通过将其在碱性溶液中分解成DMS来进行.作者采用此方法实测了黄海中DMS和DMSP的含量, 获得了理想的结果. 相似文献
9.
黄、渤海二甲基硫化物的浓度分布与迁移转化速率研究 总被引：2，自引：1，他引：1
于2015年8-9月对黄、渤海海域进行现场调查,研究了海水中二甲基硫（DMS）、β-二甲巯基丙酸内盐（DMSP）、二甲亚砜（DMSO）的浓度分布、相互关系及影响因素,测定了DMS的生物生产与消耗、光化学氧化和海-气扩散速率,对DMS的迁移转化速率进行综合评价。结果表明:表层海水中DMS、溶解态DMSP（DMSPd）、颗粒态DMSP（DMSPp）、溶解态DMSO（DMSOd）和颗粒态DMSO（DMSOp）浓度的平均值分别为（6.12±3.01）nmol/L、（6.03±3.45）nmol/L、（19.47±9.15）nmol/L、（16.85±8.34）nmol/L和（14.37±7.47）nmol/L,整体呈现近岸高远海低,表层高底层低的趋势。DMS、DMSPd和DMSOp浓度与叶绿素（Chl a）浓度存在显著的相关性。表层海水中DMS光氧化速率顺序为:kUVA > kUVB > k可见,其中UVA波段占光氧化的70.8%。夏季黄、渤海微生物消耗、光氧化及海-气扩散对DMS去除的贡献率分别为32.4%、34.5%和33.1%,表明3种去除途径作用相当。黄、渤海DMS海-气通量变化范围为0.79~48.45 μmol/（m2·d）,平均值为（11.87±11.35）μmol/（m2·d）。 相似文献
10.
辽河口海域N2O分布特征和海气通量研究 总被引：2，自引：0，他引：2
于2007年5月份(枯水期)和8月份(丰水期)采集辽河口区域大气样品及水样,应用气相色谱及静态顶空法测定大气及海水中溶解N2O的浓度,并计算不同站位的N2O通量。结果表明:辽河口区域水体中溶解N2O浓度存在着明显的时空变化,5月份河口区域水体中N2O浓度高于8月份,且河流段溶解N2O浓度大于近海岸海域。水中溶解N2O浓度及溶解氧浓度呈显著的负相关关系。在枯水期和丰水期,所有站位的N2O均处于过饱和状态,N2O气体从水体向大气排出,辽河口区域是大气中N2O的一个排放源。 相似文献
11.
Biogeochemical ocean-atmosphere transfers in the Arabian Sea 总被引：2，自引：2，他引：2
S. Wajih A. Naqvi Hermann W. Bange Stuart W. Gibb Catherine Goyet Angela D. Hatton Robert C. Upstill-Goddard 《Progress in Oceanography》2005,65(2-4):116
Transfers of some important biogenic atmospheric constituents, carbon dioxide (CO2), methane (CH4), molecular nitrogen (N2), nitrous oxide (N2O), nitrate , ammonia (NH3), methylamines (MAs) and dimethylsulphide (DMS), across the air–sea interface are investigated using published data generated mostly during the Arabian Sea Process Study (1992–1997) of the Joint Global Ocean Flux Study (JGOFS). The most important contribution of the region to biogeochemical fluxes is through the production of N2 and N2O facilitated by an acute, mid-water deficiency of dissolved oxygen (O2); emissions of these gases to the atmosphere from the Arabian Sea are globally significant. For the other constituents, especially CO2, even though the surface concentrations and atmospheric fluxes exhibit extremely large variations both in space and time, arising from the unique physical forcing and associated biogeochemical environment, the overall significance in terms of their global fluxes is not much because of the relatively small area of the Arabian Sea. Distribution and air–sea exchanges of some of these constituents are likely to be greatly influenced by alterations of the subsurface O2 field forced by human-induced eutrophication and/or modifications to the regional hydrography. 相似文献
12.
A spectral range of 920 to 960 cm?1 is chosen for satellite measurements of the CO2 content in the atmosphere with a correlation method. The optimal transmission function of the measured gas in the correlation channel of the radiometer is estimated. It is shown that the effects that atmospheric gases (H2O, CO, O3, N2O, and CH4) and errors in specifying the land-surface temperature and the vertical air-temperature distribution have on errors in measuring the CO2 content throughout the entire atmospheric thickness may reach several percent. 相似文献
13.
湿地生态系统是影响气候变化的活性气体的重要“源”或“汇”,随着人类活动的增加和气候变化的加剧,湿地生态系统活性气体对全球气候变化的影响越来越受到关注。已开展的研究主要集中于二氧化碳(CO2)、甲烷(CH4)、氧化亚氮(N2O)和二甲基硫(DMS)等活性气体。本文综述了湿地生态系统CO2、CH4、N2O和DMS的交换通量、时空变化特征以及影响因素。然而,目前对湿地生态系统活性气体的研究还不够系统和深入,对不同类型湿地的活性气体的源汇格局,碳氮硫的耦合作用机制、人类活动和环境压迫的影响等开展系统地研究,才能定量评价其对全球气候变化的贡献,并阐明变化趋势。 相似文献
14.
A. A. Vinogradova E. I. Fedorova I. B. Belikov A. S. Ginzburg N. F. Elansky A. I. Skorokhod 《Izvestiya Atmospheric and Oceanic Physics》2007,43(5):599-611
Temporal variations in the surface concentrations of two greenhouse gases (carbon dioxide and methane) in the atmosphere over a large city are studied on the basis of the data obtained during the 2003–2005 observations at a Moscow station for environmental monitoring. This station is based on the TROICA mobile observatory and located at the meteorological station of the Faculty of Geography, Moscow State University, on Vorob’evy gory. The methods of isolating the background concentrations of greenhouse gases under urban conditions are proposed, and the excess concentrations of CO2 and CH4 over their background values are estimated for different seasons and times of day. The CO2 and CH4 concentrations are shown to have more pronounced diurnal cycles in summer than in winter. The main causes of temporal variations in the surface concentrations of CO2 and CH4 under urban conditions and the differences between the mean concentrations of these greenhouse gases in Moscow and other areas of Russia are analyzed. It is shown that variations in the surface concentrations of carbon dioxide and methane on different time scales are caused by different atmospheric processes (global circulation, mesoscale gravity waves, surface temperature inversions, etc.) 相似文献
15.
《Deep Sea Research Part II: Topical Studies in Oceanography》2009,56(26):2918-2927
Atmospheric trace gas measurements were conducted during SEEDS-II. Atmospheric dimethylsulfide (DMS) was continuously measured by GC-MS during the R/V Hakuho cruise. Further, ambient air was sampled into canisters (42 samples) and analyzed by GC-MS and GC-FID for various biogenic and anthropogenic volatile organic compounds (VOCs) after the cruise. CO, O3, SO2, and NOx were monitored continuously aboard the ship.A fertilization experiment was conducted in a high-nitrate, low-chlorophyll (HNLC) region (48°N, 165°E). The atmospheric concentrations inside a patch (fertilized area) were compared with those outside it (natural area); however, clear differences were not observed for biogenic trace gasses (DMS, CH3Cl, CH3I, isoprene, and alkenes) in the atmosphere. However, a high DMS concentration was observed over the northwestern Pacific Ocean. The fertilized area was also observed by R/V Kilo Moana, and DMS was measured by GC-FPD. A good agreement was observed between the results of the measurements made aboard the two independent ships by different measurement methods.The atmospheric SO2 concentration was compared with the atmospheric DMS concentration. The SO2 concentration was found to vary with the atmospheric DMS concentration. A diurnal variation of the atmospheric DMS concentration was observed around the fertilized region. The DMS content tends to increase during the night and decrease during the day. A box model calculation was conducted to explain the diurnal variation of the atmospheric DMS. Since there was no diurnal variation of the wind speed, a constant DMS flux from the ocean surface was assumed. Further, the atmospheric OH radical concentration was assumed to be dependent on sunlight. The box model can roughly reproduce the atmospheric DMS diurnal variation mainly caused by its removal reaction with OH radicals. 相似文献
16.
Seasonal Study of Methane and Nitrous Oxide in the Coastal Waters of the Southern Baltic Sea 总被引：2，自引：0，他引：2
H.W. Bange S. Dahlke R. Ramesh L.-A. Meyer-Reil S. Rapsomanikis M.O. Andreae 《Estuarine, Coastal and Shelf Science》1998,47(6):807-817
Atmospheric and dissolved methane (CH4) and nitrous oxide (N2O) were measured in the unique coastal ecosystem of theBoddenwaters, including the western Oder estuary, (southern Baltic Sea) during five campaigns between 1994 and 1997. The CH4saturations, ranging from 105–15 500%, showed great spatial and temporal variability with maximum values in September and minimum values in December. The N2O saturations were in the range of 91–312% with a maximum in March. Enhanced concentrations of both gases were observed only in the western Oder estuary near the mouth of the Peene River. Thus, we conclude that the distributions of CH4and N2O in the investigatedBoddenwaters are, directly or indirectly, linked to the Peene River runoff and not to the Oder River. Our estimate of the annual CH4emissions from theBoddenwaters to the atmosphere indicates a significant contribution (c. 17%) to the overall CH4emissions from the Baltic Sea. In contrast, theBoddenwaters represent only a small source for atmospheric N2O.CH4production rates estimated from sediment slurry experiments revealed a significant spatial variability and indicated that methanogenic activity was related to acetate consumption in the surface sediment layer. Sedimentary CH4production might depend on different amounts of accumulation of organic material. 相似文献
17.
The invasions of the alien species such as Spartina alterniflora along the northern Jiangsu coastlines have posed a threat to biodiversity and the ecosystem function.Yet,limited attention has been given to their potential influence on greenhouse gas(GHG) emissions,including the diurnal variations of GHG fluxes that are fundamental in estimating the carbon and nitrogen budget.In this study,we examined the diurnal variation in fluxes of carbon dioxide(CO_2),methane(CH_4),and nitrous oxide(N2O) from a S.alterniflora intertidal flat in June,October,and December of 2013 and April of 2014 representing the summer,autumn,winter,and spring seasons,respectively.We found that the average CH_4 fluxes on the diurnal scale were positive during the growing season while negative otherwise.The tidal flat of S.alterniflora acted as a source of CH_4 in summer(June) and a combination of source and sink in other seasons.We observed higher diurnal variations in the CO_2 and N_2O fluxes during the growing season(1 536.5 mg CO_2 m~(–2) h~(–1) and 25.6 μg N_2O m~(–2) h~(–1)) compared with those measured in the non-growing season(379.1 mg CO_2 m~(–2) h~(–1) and 16.5 μg N_2O m~(–2) h~(–1)).The mean fluxes of CH_4 were higher at night than that in the daytime during all the seasons but October.The diurnal variation in the fluxes of CO_2 in June and N_2O in December fluctuated more than that in October and April.However,two peak curves in October and April were observed for the diurnal changes in CO_2 and N_2O fluxes(prominent peaks were found in the morning of October and in the afternoon of April,respectively).The highest diurnal variation in the N_2O fluxes took place at 15:00(86.4 μg N_2O m~(–2) h~(–1)) in June with an unimodal distribution.Water logging in October increased the emission of CO_2(especially at nighttime),yet decreased N_2O and CH_4 emissions to a different degree on the daily scale because of the restrained diffusion rates of the gases.The seasonal and diurnal variations of CH_4 and CO_2 fluxes did not correlate to the air and soil temperatures,whereas the seasonal and diurnal variation of the fluxes of N_2O in June exhibited a significant correlation with air temperature.When N_2O and CH_4 fluxes were converted to CO_2-e equivalents,the emissions of N_2O had a remarkable potential to impact the global warming.The mean daily flux(MF) and total daily flux(TDF) were higher in the growing season,nevertheless,the MF and TDF of CO_2 were higher in October and those of CH_4 and N_2O were higher in June.In spite of the difference in the optimal sampling times throughout the observation period,our results obtained have implications for sampling and scaling strategies in estimating the GHG fluxes in coastal saline wetlands. 相似文献
18.
T.D. Jickells P.S. Liss S. Turner J. Read L.M. Cardenas F. Carse M. Hamren-Larssen M. Steinke A. Thompson S.D. Archer C.S. Law P.D. Nightingale C.E. Widdicombe L.C. Gilpin G. Savidge P. Hadziabdic R. Upstill-Goddard R. Simó A. Allen 《Progress in Oceanography》2008,76(3):366-398
We report the results of an experiment in the Northeast Atlantic in which sulphur hexafluoride (SF6) was released within an eddy and the behaviour of trace gases, nutrients and productivity followed within a Lagrangian framework over a period of 24 days. Measurements were also made in the air above the eddy in order to estimate air-sea exchange rates for some components. The physical, biological and biogeochemical properties of the eddy resemble those of other eddies studied in this area, suggesting that the results we report may be applicable beyond the specific eddy studied. During a period of low wind speed at the start of the experiment, we are able to quantitatively describe and balance the nutrient and carbon budgets for the eddy. We also report concentrations of various trace gases in the region which are similar to those observed in other studies and we estimate exchange rates for several trace gases. We show that the importance of gas exchange over other loss terms varies with time and also varies for the different gases. We show that the various trace gases considered (CO2, dimethyl sulphide (DMS), N2O, CH4, non-methane-hydrocarbons, methyl bromide, methyl iodide and volatile selenium species) are all influenced by physical and biological processes, but the overall distribution and temporal variability of individual gases are different to one another. A storm disrupted the stratification in the eddy during the experiment, resulting in enhanced nutrient supply to surface waters, enhanced gas exchange rates and a change in plankton community, which we quantify, although overall productivity was little changed. Emphasis is placed on the regularity of storms in the temperate ocean and the importance of these stochastic processes in such systems. 相似文献
19.
Natural hydrocarbon seeps in a marine environment are one of the important contributors to greenhouse gases in the atmosphere,including methane,which is significant to the global carbon cycling and climate change.Four hydrocarbon seep areas,the Lingtou Promontory,the Yinggehai Rivulet mouth,the Yazhou Bay and the Nanshan Promontory,occurring in the Yinggehai Basin delineate a near-shore gas bubble zone.The gas composition and geochemistry of venting bubbles and the spatial distribution of hydrocarbon seeps are surveyed on the near-shore Lingtou Promontory.The gas composition of the venting bubbles is mainly composed of CO_2,CH_4,N_2 and O_2,with minor amounts of non-methane hydrocarbons.The difference in the bubbles' composition is a possible consequence of gas exchange during bubble ascent.The seepage gases from the seafloor are characterized by a high CO_2 content(67.35%) and relatively positive δ~(13)C_(V_PDB) values(-0.49×10~(-3)-0.86×10~(-3)),indicating that the CO_2 is of inorganic origin.The relatively low CH_4 content(23%) and their negative δ~(13)C_(V-PDB) values(-34.43×10~(-3)--37.53×10~(-3)) and high ratios of C_1 content to C_(1-5) one(0.98-0.99)as well point to thermogenic gases.The hydrocarbon seeps on the 3.5 Hz sub-bottom profile display a linear arrangement and are sub-parallel to the No.1 fault,suggesting that the hydrocarbon seeps may be associated with fracture activity or weak zones and that the seepage gases migrate laterally from the central depression of the Yinggehai Basin. 相似文献