Seasonal and daily variation of mercury evasion at coastal and off shore sites from the Mediterranean Sea   总被引：3，自引：0，他引：3  

Maria E. Andersson  Katarina Grdfeldt  Ingvar Wngberg  Francesca Sprovieri  Nicola Pirrone  Oliver Lindqvist 《Marine Chemistry》2007,104(3-4):214-226

Dissolved gaseous mercury (DGM) was measured continuously using two newly developed techniques and a manual technique. The continuous techniques were based on the equilibrium between the aqueous and gaseous phase (DGM = Hg_extr / H', Hg_extr is the measured mercury concentration in the gas phase, H' is the Henry's Law coefficient at the desired temperature). In order to calculate the annual mercury evasion from the Mediterranean Sea, diurnal and seasonal measurements of DGM, total gaseous mercury in air (TGM), water temperature and wind speed were performed. During August 2003, March–April 2004 and October–November 2004 measurements of these parameters were conducted on board the RV Urania. The continuous measurements of DGM showed a diurnal variation in concentration, at both coastal and off shore sites, with higher concentrations during daytime than nighttime. The concentration difference could be as large as 130 fM between day and night. The degree of saturation was calculated directly from the measurements, S = Hg_extr / TGM and was found to vary between the different seasons. The highest average degree of saturation (850%) and the largest variation in saturation (600–1150%) was observed during the summer. The spring showed the lowest variation (260–360%) and the lowest average degree of saturation (320%). The autumn also showed a large variation in saturation (500–1070%) but a lower average (740%) compared to the summer cruise. This might be explained by the temperature difference between the different seasons, since that parameter varied the most. The flux from the sea surface was calculated using the gas exchange model developed by Nightingale et al. [Nightingale, P.D., Malin, G., Law, C.S., Watson, A.J., Liss, P.S., Liddicoat, M.I., Boutin, J., Upstill-Goddard, R. C., 2000. In situ evaluation of air–sea gas exchange parameterization using novel conservative and volatile tracers. Global Biogeochemical Cycles, 14(1):373–387]. The evasion varied between the different seasons with the highest evasion during the autumn, 24.6 pmol m^− 2 h^− 1. The summer value was estimated to 22.3 pmol m^− 2 h^− 1 and the spring to 7.6 pmol m^− 2 h^− 1. Using this data the yearly evasion from the Mediterranean Sea surface was estimated to 77 tons.  相似文献   

Reprint of “Seasonal and daily variation of mercury evasion at coastal and off shore sites from the Mediterranean Sea”     

Maria E. Andersson  Katarina Gårdfeldt  Ingvar Wängberg  Francesca Sprovieri  Nicola Pirrone  Oliver Lindqvist 《Marine Chemistry》2007

Dissolved gaseous mercury (DGM) was measured continuously using two newly developed techniques and a manual technique. The continuous techniques were based on the equilibrium between the aqueous and gaseous phase (DGM = Hg_extr / H', Hg_extr is the measured mercury concentration in the gas phase, H' is the Henry's Law coefficient at the desired temperature). In order to calculate the annual mercury evasion from the Mediterranean Sea, diurnal and seasonal measurements of DGM, total gaseous mercury in air (TGM), water temperature and wind speed were performed. During August 2003, March–April 2004 and October–November 2004 measurements of these parameters were conducted on board the RV Urania. The continuous measurements of DGM showed a diurnal variation in concentration, at both coastal and off shore sites, with higher concentrations during daytime than nighttime. The concentration difference could be as large as 130 fM between day and night. The degree of saturation was calculated directly from the measurements, S = Hg_extr / TGM and was found to vary between the different seasons. The highest average degree of saturation (850%) and the largest variation in saturation (600–1150%) was observed during the summer. The spring showed the lowest variation (260–360%) and the lowest average degree of saturation (320%). The autumn also showed a large variation in saturation (500–1070%) but a lower average (740%) compared to the summer cruise. This might be explained by the temperature difference between the different seasons, since that parameter varied the most. The flux from the sea surface was calculated using the gas exchange model developed by Nightingale et al. [Nightingale, P.D., Malin, G., Law, C.S., Watson, A.J., Liss, P.S., Liddicoat, M.I., Boutin, J., Upstill-Goddard, R. C., 2000. In situ evaluation of air–sea gas exchange parameterization using novel conservative and volatile tracers. Global Biogeochemical Cycles, 14(1):373–387]. The evasion varied between the different seasons with the highest evasion during the autumn, 24.6 pmol m^− 2 h^− 1. The summer value was estimated to 22.3 pmol m^− 2 h^− 1 and the spring to 7.6 pmol m^− 2 h^− 1. Using this data the yearly evasion from the Mediterranean Sea surface was estimated to 77 tons.  相似文献   

Factors influencing the daily behaviour of dissolved gaseous mercury concentration in the Mediterranean Sea     

L. Fantozzi  R. Ferrara  F.P. Frontini  F. Dini 《Marine Chemistry》2007

Mercury evasional fluxes from the sea surface into the atmosphere play an important role in the Hg biogeochemical cycle, especially in the Mediterranean basin, which is characterized by the presence of large cinnabar deposits, intense solar radiation and high temperatures for many months of the year. Since the available experimental methodologies to measure mercury flux can be used only in good weather conditions, at present it is necessary to make use of exchange models that require the knowledge of the dissolved gaseous mercury (DGM) concentration in seawater. In this paper, the main factors affecting DGM levels are discussed considering the determination of the DGM daily behaviour in different meteo-marine and weather conditions at coastal and offshore locations of the Mediterranean basin. A fully automatic device for continuous analyses of DGM concentration with a high time resolution was used. Results show that the daily trend of DGM concentration tracks that of the solar radiation intensity, often mapping the movement of the clouds. DGM levels can be decreased by the presence of high winds that increase mercury evasion from the water surface, as well as by the mixing of the surface water layer. The presence of high levels of dissolved organic matter favours the photo-induced reduction of mercury as observed by the measurements performed in a lagoon water.  相似文献   

Variation of diffuse attenuation coefficient of downwelling irradiance in the Arctic Ocean     

WANG Weibo  ZHAO Jinping 《海洋学报(英文版)》2014,33(6):53-62

The diffuse attenuation coefficient(Kd) for downwelling irradiance is calculated from solar irradiance data measured in the Arctic Ocean during 3rd and 4th Chinese National Arctic Research Expedition(CHINARE), including 18 stations and nine stations selected for irradiance profiles in sea water respectively. In this study, the variation of attenuation coefficient in the Arctic Ocean was studied, and the following results were obtained. First, the relationship between attenuation coefficient and chlorophyll concentration in the Arctic Ocean has the form of a power function. The best fit is at 443 nm, and its determination coefficient is more than 0.7. With increasing wavelength, the determination coefficient decreases abruptly. At 550 nm, it even reaches a value lower than 0.2. However, the exponent fitted is only half of that adapted in low-latitude ocean because of the lower chlorophyll-specific absorption in the Arctic Ocean. The upshot was that, in the case of the same chlorophyll concentration, the attenuation caused by phytoplankton chlorophyll in the Arctic Ocean is lower than in low-latitude ocean. Second, the spectral model, which exhibits the relationship of attenuation coefficients between 490 nm and other wavelength, was built and provided a new method to estimate the attenuation coefficient at other wavelength, if the attenuation coefficient at 490 nm was known. Third, the impact factors on attenuation coefficient, including sea ice and sea water mass, were discussed. The influence of sea ice on attenuation coefficient is indirect and is determined through the control of entering solar radiation. The linear relationship between averaging sea ice concentration(ASIC, from 158 Julian day to observation day) and the depth of maximum chlorophyll is fitted by a simple linear equation. In addition, the sea water mass, such as the ACW(Alaskan Coastal Water), directly affects the amount of chlorophyll through taking more nutrient, and results in the higher attenuation coefficient in the layer of 30–60 m. Consequently, the spectral model of diffuse attenuation coefficient, the relationship between attenuation coefficient and chlorophyll and the linear relationship between the ASIC and the depth of maximum chlorophyll, together provide probability for simulating the process of diffuse attenuation coefficient during summer in the Arctic Ocean.  相似文献   

The saturation of calcite and aragonite in the Arctic Ocean   总被引：1，自引：0，他引：1  

Sara Jutterstrm  Leif G. Anderson 《Marine Chemistry》2005,94(1-4):101

We report on the chemical saturation of CaCO₃ in the waters of the Arctic Ocean calculated from total alkalinity (A_T) and total dissolved inorganic carbon (C_T). Data based on four different expeditions are presented: International Arctic Ocean Expedition (IAOE-91), Arctic Ocean Section 94 (AOS94), Polarstern Arctic '96 expedition (ACSYS 96), and Joint Ocean Ice Study 97 (JOIS 97). The results show a lysocline at around 3500 m for aragonite and that most of the Arctic Ocean sea floor lies above the lysocline for calcite. The only anomaly is the low degree of saturation at the shelf break depth in the Canadian Basin seen in the sections of the AOS94 and JOIS 97 cruises, correlated with nutrient maxima and very low O₂ concentration, suggesting decomposition of organic matter. The insignificant variability in degree of saturation between the deep waters of the different basins in the Arctic Ocean indicates a very low sedimentation/remineralisation of organic soft matter.  相似文献   

Halocarbons associated with Arctic sea ice     

《Deep Sea Research Part I: Oceanographic Research Papers》2014

Short-lived halocarbons were measured in Arctic sea–ice brine, seawater and air above the Greenland and Norwegian seas (~81°N, 2–5°E) in mid-summer, from a melting ice floe at the edge of the ice pack. In the ice floe, concentrations of C₂H₅I, 2-C₃H₇I and CH₂Br₂ showed significant enhancement in the sea ice brine, of average factors of 1.7, 1.4 and 2.5 times respectively, compared to the water underneath and after normalising to brine volume. Concentrations of mono-iodocarbons in air are the highest ever reported, and our calculations suggest increased fluxes of halocarbons to the atmosphere may result from their sea–ice enhancement. Some halocarbons were also measured in ice of the sub-Arctic in Hudson Bay (~55°N, 77°W) in early spring, ice that was thicker, colder and less porous than the Arctic ice in summer, and in which the halocarbons were concentrated to values over 10 times larger than in the Arctic ice when normalised to brine volume. Concentrations in the Arctic ice were similar to those in Antarctic sea ice that was similarly warm and porous. As climate warms and Arctic sea ice becomes more like that of the Antarctic, our results lead us to expect the production of iodocarbons and so of reactive iodine gases to increase.  相似文献   

Distribution of radium-224 in the western Arctic Ocean     

QIU Yusheng  CHEN Min  LI Yanping 《海洋学报(英文版)》2005,24(6):109-116

1Introduction ThephysicalcharacteristicsintheArcticOcean includewidecontinentalshelves,accountingfor36% oftheocean’ssurfacearea(MooreandSmith,1986) withseasonalicecover.Theprincipalwatersentering theArcticOceanarefromtheNorthAtlanticviathe FramStraitandtheBarentsSea,andtheNorthPacific viatheBeringStrait.Withinthearcticinterior,thewa- tersjoininthelarge-scalecirculationandaresubse- quentlymodifiedbyprocessesofair/sea/iceinterac- tion,riverinflow,andexchangewithsurrounding shelves.Howeve…  相似文献   

北冰洋夏季的海雾   总被引：6，自引：1，他引：6  

解思梅  薛振和  曲绍厚  姜德中  邹斌 《海洋学报》2001,23(6):40-50

以中国首次北极科学考察采用国内外海冰、大气和海洋的先进观测设备,获得海、陆、空的同步或准同步观测资料为基础,重点研究北冰洋的海雾.发现在北冰洋大范围被海冰覆盖或冰水相间的洋面上,能够形成平流雾、辐射雾和蒸汽雾.每种海雾的特点和形成的物理机制不同.在北冰洋的南部,由于暖湿气流充分,易形成持续时间长、浓度大的平流雾;在冰盖和大浮冰块上,由于冰雪面的强辐射冷却,容易形成稳定的辐射雾;在浮冰区能够形成像开锅的蒸汽一样的蒸汽雾.指出在北冰洋形成多种海雾原因是海冰的分布及独特的物理特性造成下垫面性质的复杂化,产生的海气相互作用复杂化的结果,特别是冰雪面的反照率高,不能吸收极昼期充足的太阳辐射.冰又是热的不良导体,成为海气热交换的屏障,在浮冰区由于冰屏障的破碎,海气交换活跃.海洋以潜热的形式向大气输送热量,以蒸汽雾的形式反映出海气热交换的程度和对气候影响的一种表现形式.提出在蒸汽雾发生的过程中,海洋以感热的形式向大气输送热量.  相似文献   

北冰洋浮游生物空间分布及其季节变化的模拟   总被引：3，自引：1，他引：2  

魏皓  赵伟  罗晓凡  聂红涛  胡宪敏  鹿有余 《海洋学报》2019,41(9):65-79

低营养级浮游生物生态动力过程对环境变化的响应非常敏感。随着全球气候变化加剧,北冰洋正在经历快速的环境变化。厘清北冰洋低营养级浮游生物季节分布与变化特征是探究北冰洋生态系统对环境快速变化响应的前提,也是评估北极海区固碳能力的重要依据。基于此,本文构建了海洋–海冰–生物地球化学循环模型,并对北冰洋叶绿素浓度以及浮游生物结构的时空变化特征进行了模拟,结果表明:(1)北冰洋表层叶绿素浓度的峰值主要出现在5月,且太平洋一侧叶绿素浓度高于大西洋一侧;随着海水层化,表层受营养盐限制的海区呈现次表层叶绿素浓度最大值现象,且由陆架向海盆,次表层叶绿素浓度最大值层逐渐加深;9月,叶绿素浓度高值重回水体上层,太平洋一侧海区表层叶绿素浓度呈现较为明显的次峰值。(2)由于太平洋和大西洋入流营养盐浓度及结构的不同,北冰洋表层浮游生物群落结构存在明显空间差异。太平洋一侧,硅藻和中型浮游动物占优,硅藻在5月和9月出现生物量峰值,微型浮游植物在3月、5月和6月维持相对较高生物量;而大西洋一侧,在早春－春末夏初－夏秋经历了微型浮游植物－硅藻－微型浮游植物的演替,总体而言,微型浮游植物和微型浮游动物占优。此外,两侧海区浮游动物浓度峰值相较浮游植物滞后约半月。  相似文献   

北冰洋表层积雪中7Be、210Po和210Pb的分布特征     

刘楚越  钟强强  黄德坤  陈随缘  王浩  于涛 《海洋学报》2021,43(11):70-76

大气输送的放射性核素7Be、210Po和210Pb,可以作为研究北冰洋大气沉降通量、海洋现代沉积以及海冰中物质传输的重要示踪剂,已被广泛应用于包括气团运动、土壤侵蚀以及水系统中颗粒物循环过程的研究。本文报道了2018年北极高纬度浮冰区表层积雪中7Be、210Po和210Pb的活度特征。7Be、210Po和210Pb的比活度变化范围分别为33.6～632.68 mBq/L、36.2～87.5 mBq/L、30.9～194.49 mBq/L。本文的研究发现,北冰洋表层积雪中7Be和210Pb比活度小于中纬度大陆地区。研究区域表层积雪中7Be的比活度随着纬度的增加而增加。此外,表层积雪中210Po/210Pb活度比值范围为0.70～1.48 (平均为0.93),210Po与210Pb活度已基本达到平衡,表明积雪样品年龄可能较“老”。  相似文献   

Total inorganic carbon in sea ice     

A. P. Nedashkovsky  M. G. Shvetsova 《Oceanology》2010,50(6):861-868

The method proposed for determining the total inorganic carbon (TC) concentrations in sea ice (Arctic region, North Pole-35 expedition) based on the measurement of the total alkalinity (TA) and the pH in the melt waters without the CO₂ exchange with the atmosphere is considered. It is shown that the TC/Sal and TA/TC values through the entire ice section remain similar to these parameters in the subice water. The surface snow and the uppermost ice layers are characterized by elevated TA/TC values, which indicate the reaction Ca²⁺ + 2HCO₃⁻ = ↓CaCO₃ + ↑CO₂ + H₂O. The release of CO₂ to the atmosphere due to the decomposition of calcium hydrocarbonate is as high as ∼20 mmol/m². The meltwater of the examined ice is undersaturated with CO₂, which may result in a sink of atmospheric CO₂ (∼30 mmol/m²).  相似文献   

Distribution of Calanus finmarchicus in the northern North Atlantic and Arctic Ocean—Expatriation and potential colonization     

Hans-Jürgen Hirche  Ksenia Kosobokova 《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2729

The distribution of Calanus finmarchicus was studied on a transect across the central Greenland Sea, and on five transects from the Eurasian shelves across the Atlantic Inflow in the Arctic Ocean. Stage composition was used as an indicator for successful growth; gonad maturity and egg production were taken as indicators for reproductive activity. On the Arctic Ocean transects, these parameters were measured simultaneously from the sibling species Calanus glacialis. Response of egg production rate to different temperatures at optimal food conditions was very similar between both species in the laboratory. C. finmarchicus was present at all stations studied, but young developmental stages were only present close to the regions of submergence of Atlantic water under the Polar water. This together with a decreasing abundance and biomass from west to east along the Atlantic Inflow in the Arctic Ocean and reproductive failure indicates that C. finmarchicus is expatriated in the Arctic Ocean. We hypothesize that the late availability of food in the Arctic Ocean, rather than low temperature per se, limits reproductive success. Better reproductive success in the very low temperature regions of the Return Atlantic Current and the marginal ice zone in the Greenland Sea supports this hypothesis. The possibility for a replacement of C. glacialis by C. finmarchicus and consequences for the ecosystem after increasing warming of the Arctic are discussed.  相似文献   

2010年西北冰洋浮游植物区域差异与环境关系     

林更铭  王彦国  陈扬航  叶又茵  王雨  杨清良 《海洋学报(英文版)》2018,37(4):109-121

Global warming has caused Arctic sea ice to rapidly retreat,which is affecting phytoplankton,the primary producers at the base of the food chain,as well as the entire ecosystem.However,few studies with large spatial scales related to the Arctic Basin at high latitude have been conducted.This study aimed to investigate the relationship between changes in phytoplankton community structure and ice conditions.Fifty surface and 41 vertically stratified water samples from the western Arctic Ocean(67.0°–88°26′N,152°–178°54′W) were collected by the Chinese icebreaker R/V Xuelong from July 20 to August 30,2010 during China's fourth Arctic expedition.Using these samples,the species composition,spatial distribution,and regional disparities of phytoplankton during different stages of ice melt were assessed.A total of 157 phytoplankton taxa(5 μm) belonging to 69 genera were identified in the study area.The most abundant species were Navicula pelagica and Thalassiosira nordenskioeldii,accounting for 31.23% and 14.12% of the total phytoplankton abundance,respectively.The average abundance during the departure trip and the return trip were 797.07×10~2 cells/L and 84.94×10~2 cells/L,respectively.The highest abundance was observed at Sta.R09 in the north of Herald Shoal,where Navicula pelagica was the dominant species accounting for 59.42% of the abundance.The vertical distribution of phytoplankton abundance displayed regional differences,and the maximum abundances were confined to the lower layers of the euphotic zone near the layers of the halocline,thermocline,and nutricline.The species abundance of phytoplankton decreased from the low-latitude shelf to the high-latitude basin on both the departure and return trips.The phytoplankton community structure in the shallow continental shelf changed markedly during different stages of ice melt,and there was shift in dominant species from centric to pennate diatoms.Results of canonical correspondence analysis(CCA) showed that there were two distinct communities of phytoplankton in the western Arctic Ocean,and water temperature,ice coverage and silicate concentration were the most important environmental factors affecting phytoplankton distribution in the surveyed sea.These findings will help predict the responses of phytoplankton to the rapid melting of Arctic sea ice.  相似文献   

Spatial variability in the partial pressures of CO₂ in the northern Bering and Chukchi seas   总被引：2，自引：0，他引：2  

Liqi Chen  Zhongyong Gao   《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2619

In the summers of 1999 and 2003, the 1st and 2nd Chinese National Arctic Research Expeditions measured the partial pressure of CO₂ in the air and surface waters (pCO₂) of the Bering Sea and the western Arctic Ocean. The lowest pCO₂ values were found in continental shelf waters, increased values over the Bering Sea shelf slope, and the highest values in the waters of the Bering Abyssal Plain (BAP) and the Canadian Basin. These differences arise from a combination of various source waters, biological uptake, and seasonal warming. The Chukchi Sea was found to be a carbon dioxide sink, a result of the increased open water due to rapid sea-ice melting, high primary production over the shelf and in marginal ice zones (MIZ), and transport of low pCO₂ waters from the Bering Sea. As a consequence of differences in inflow water masses, relatively low pCO₂ concentrations occurred in the Anadyr waters that dominate the western Bering Strait, and relatively high values in the waters of the Alaskan Coastal Current (ACC) in the eastern strait. The generally lower pCO₂ values found in mid-August compared to at the end of July in the Bering Strait region (66–69°N) are attributed to the presence of phytoplankton blooms. In August, higher pCO₂ than in July between 68.5 and 69°N along 169°W was associated with higher sea-surface temperatures (SST), possibly as an influence of the ACC. In August in the MIZ, pCO₂ was observed to increase along with the temperature, indicating that SST plays an important role when the pack ice melts and recedes.  相似文献   

Effects of the duration of exposure to mercuric chloride on the embryogenesis of the estuarine teleost, Fundulus heteroclitus     

John R. Sharp  Jerry M. Neff 《Marine environmental research》1980,3(3):195-213

Embryos of Fundulus heteroclitus in the 4–8 cell stage were exposed nine Hg⁺⁺ (as mercuric chloride) concentrations from 0 to 100 μg/litre (ppb) for 32 days, 5 days, 2 days and 1 day. All but the chronically (32-day) exposed embryos were allowed to continue development in mercury-free water (20% S) after the exposure period to determine the effect of duration of exposure on three parameters of development. Ninety-six hour survival, total hatching success and per cent incidence of lateral spinal curvature were measured. Only embryos exposed to mercury for a single day showed a significant increase in survival in comparison with embryos exposed for a longer period of time after four days of development. Under all conditions of exposure, survival was reduced at concentrations greater than 40 ppb Hg⁺⁺. Hatching success of chronically exposed embryos was significantly reduced at concentrations greater than 10 ppb Hg⁺⁺. Significant increases in total hatchability were effected by reducing the duration of exposure to five days and one day. Of eleutheroembryos emerging following chronic exposure to mercury, increases in the incidence of lateral spinal curvature were noted at all concentrations above 20 ppb Hg⁺⁺. Significant reductions of this disorder were observed among eleutheroembryos exposed to mercury for 5 days, 2 days or 1 day. Of the three parameters measured, the incidence of lateral spinal curvature and the resulting VH₅₀ value gave a more sensitive evaluation of the embryotoxic effects of Hg⁺⁺ as mercuric chloride on the estuarine teleost, Fundulus heteroclitus.  相似文献   

Numerical modeling of the Arctic Ocean ice system response to variations in the atmospheric circulation from 1948 to 2007   总被引：1，自引：1，他引：0  

E. N. Golubeva  G. A. Platov 《Izvestiya Atmospheric and Oceanic Physics》2009,45(1):137-151

The results of model calculations aimed at reproducing climate changes in the Arctic Ocean due to variations in the atmospheric circulation are presented. The combined ocean-ice numerical model is based on NCAR/NCEP reanalysis data and its modified version of CIAF on the state of the lower atmosphere, radiative fluxes, and precipitation from 1948 to the present. The numerical experiments reveal the effect of the ice cover, water circulation, and thermohaline structure of the Arctic Ocean on variations in the state of the atmosphere. We found the heating and cooling periods in the Atlantic water layer, as well as the freshwater accumulation regimes in the Canadian Basin and freshwater flow through the Fram Strait and Canadian Archipelago straits. The numerical model reproduces a reconfiguration of the water circulation of the surface and intermediate layers of the ocean, a shift in the boundary between Atlantic and Pacific waters, and a significant reduction of the ice area.  相似文献   

Detection of rapid deposition of sea ice-rafted material to the Arctic Ocean benthos using the cosmogenic tracer Be     

Lee W. Cooper  Ingvar L. Larsen  Jacqueline M. Grebmeier  S. Bradley Moran 《Deep Sea Research Part II: Topical Studies in Oceanography》2005,52(24-26):3452

During three icebreaker cruises in the Arctic Ocean under different sea-ice conditions in 2002, undisturbed benthic surface sediments were collected and assayed for the presence of a short-lived (t_1/2=53 d), particle-reactive cosmogenic radionuclide, ⁷Be, that is solely derived from atmospheric deposition. Under largely ice-covered conditions in May–June 2002, we did not detect this radionuclide in benthic surface sediments, despite significant inventories present in ice-rafted snow on the overlying sea ice (mean=86.8 Bq m⁻²±32.0 SD; n=9). During the July–August 2002 Shelf–Basin Interactions (SBI) cruise aboard the USCGC Healy and during a simultaneous cruise of the CCGS Sir Wilfrid Laurier on the Bering and Chukchi Shelf, which occupied the same general region following retreat and dissolution of Arctic ice cover, the ⁷Be present in this snow as well as surface deposition on to the sea ice-free water surface was detected in many benthic surface sediments, including some as deep as 945 m in Barrow Canyon. Inventories of ⁷Be in sediments were as high (60 Bq m⁻²) as the entire decay-corrected inventory present earlier in some snow samples collected on the sea-ice cover. Other deposition indicators such as the inventories of sediment chlorophyll, sediment oxygen respiration rates and ²³⁴Th-derived export fluxes also showed post-ice melt particle deposition and vertical transport, but in most cases the ⁷Be deposition was not tightly correlated with these other indicators, suggesting that ⁷Be sedimentation may not be controlled by the same processes. Our observations indicate that materials in sea ice, including contaminants, particulate organic, and mineral matter originating from atmospheric deposition or entrained in continental shelf sediments and rafted onto sea ice, can be rapidly transported to depth. The re-distribution of these materials as sea-ice drifts and eventually melts has the potential for impacting Arctic Ocean biogeochemical cycles and contaminant concentrations in areas of the Arctic remote from the original point of deposition.  相似文献   

西北冰洋表层沉积物中生源和陆源粗组分及其沉积环境   总被引：5，自引：4，他引：1       下载免费PDF全文

孙烨忱  王汝建  肖文申  陈建芳  程振波  陈志华  高爱国  李洪亮 《海洋学报》2011,33(2):103-114

通过中国第1至第3次北极科学考察在北冰洋西部所采集的99个表层沉积物中生源与陆源粗组分的分析,研究了该海域表层生产力的变化,有机质来源以及陆源粗颗粒物质的输入方式和影响因素.研究区域生源组分所反映的表层生产力变化与通过白令海峡进入楚科奇海的3股太平洋洋流密切相关.楚科奇海西侧高盐高营养盐的阿纳德尔流流经区域,表层生产力...  相似文献   

2008年夏季西北冰洋表层水浮游植物群落结构的色素表征及其对不同水团的响应   总被引：1，自引：0，他引：1  

金海燕  庄燕培  李宏亮  陈建芳  高生泉  季仲强  张扬 《海洋学报(英文版)》2017,36(8):109-121

本文依托2008年夏季中国第三次北极科学考察航次,对西北冰洋海盆区和楚科奇海陆架营养盐及光合色素进行了测定和分析。根据海水理化性质将研究海区分为5个区,并使用CHEMTAX软件（Mackery et al.,1996）讨论了西北冰洋不同海区浮游植物群落组成结构及其与环境因子之间的关系。结果显示在楚科奇海陆架区,太平洋入流显著影响浮游植物生物量和群落结构。高营养盐Anadyr水团以及白令陆架水控制海域,表现出高Chl a且浮游植物以硅藻为主,相反,低营养盐如阿拉斯加沿岸流控制海域,Chl a生物量低且以微型,微微型浮游植物为主。在外陆架海区,海冰覆盖情况影响着水团的物理特征及营养盐浓度水平,相应地显著影响浮游植物群落结构。在海冰覆盖区域,硅藻生物量站到总Chl a生物量的75%以上;在靠近门捷列夫深海平原海区,受相对高盐的冰融水影响（MW-HS）,营养盐浓度和Chl a浓度相对海冰覆盖区略高,浮游植物结构中微型、微微型藻类比重增加,硅藻比例则降至33%;南加拿大海盆无冰海区（IfB）,表层水盐度最淡,营养盐浓度最低,相应地显示出低Chl a生物量,表明海冰消退,开阔大洋持续时间延长,将导致低生物量及激发更小型浮游植物的生长,并不有利于有机碳向深海的有效输出。  相似文献   

Mercury concentration in the ocean     

Masakichi Nishimura  Shigeki Konishi  Katsuhiko Matsunaga  Kohtaro Hata  Tsuneo Kosuga 《Journal of Oceanography》1983,39(6):295-300

Seventy percent of 342 seawater samples collected in the Bering Sea, North and South Pacific, Japan Sea, East and South China Seas, and Indian Ocean had concentrations of “total” mercury ranging from 3 to 6 ng Hg l^?1 with an arithmetic mean of 5.3 ng l^?1 and a geometric mean of 5.0 ng l^?1. In some cases, a higher concentration was observed at the surface, at the halocline or thermocline, or in the bottom water. But in general, there was no consistent correlation between mercury concentration and depth, except for a statistical tendency for mercury concentration to be slightly higher in the surface water. This tendency suggests that mercury in the ocean is supplied from the atmosphere by rain washout. The latitudinal variation of surface mercury concentrations showed that the maximum concentration at each latitude decreased from 40°N to 30°S. This variation provides evidence that atmospheric mercury is emitted mainly from continental areas naturally or anthropogenically.  相似文献