白令海表层营养盐水平输送的镭-228示踪

对白令海表层海水228Ra的分析表明,白令海表层海水228Ra比活度从低于检测限变化至0.81 Bq/m3,低于西北冰洋陆架区的报道值。表层水228Ra比活度和228Ra/226Ra)_A.R.的空间分布均呈现由西南部中心海盆向东北部陆架区增加的趋势。由228Ra/226Ra)_A.R.和盐度的关系揭示出白令海环流、白令海陆坡流和阿拉斯加沿岸流对228Ra和228Ra/226Ra)_A.R.分布有明显影响。运用一维稳态扩散模型计算出白令海由中心海盆向东北部陆架方向上水体混合的水平涡动扩散系数为1.9×108 m2/d。结合海盆-陆架界面营养盐的水平浓度梯度,估算得硝酸盐、活性磷酸盐和活性硅酸盐由白令海中心海盆向东北部陆架区的水平输送通量,该通量对白令海东北部陆架区新生产力的贡献很小,其他途径输送的营养盐更为重要。     

莱州湾海水中营养盐分布与富营养化的关系

根据2001年5月和9月2个航次莱州湾海区海水营养盐等的调查资料,分析了该海域海水中5项营养盐的分布特征及时空变化,评价了水质的富营养化状况。结果表明,溶解无机氮的平均浓度为9.80μmol/dm3,2个季节中溶解无机氮以NO3-N浓度为最高,平均为7.61μmol/dm3,占总无机氮的77.65%,是莱州湾海水中的无机氮主要形式;活性磷酸盐的平均浓度为0.48μmol/dm3,活性硅酸盐的平均浓度为11.31μmol/dm3。研究发现,莱州湾海水中溶解无机氮和活性磷酸盐浓度分别是12 a前的2.03倍和3.2倍。DIN∶P,Si∶P,Si∶DIN比值分别为69.5,34.2,1.4;因此,磷酸盐为限制因素。按照营养状态指数值,莱州湾海区湾顶近岸海域划分为富营养化区,秋季一旦水文气象等条件适宜有发生赤潮的可能。     

桑沟湾海水中营养盐分布及潜在性富营养化分析

根据2003年8月—2004年7月桑沟湾海区12个航次海水营养盐的调查资料,分析了该海区海水营养盐的分布特征及时空变化,评价了水质的潜在性富营养化状况。结果表明,溶解无机氮的年平均浓度为10.15μmol/dm3。4个季节中溶解无机氮以NO3-N为主要存在形式,占年平均含量的78.69%,其中以秋季的含量为最高。NH3-N占无机氮年平均含量的15.11%,NO2-N占无机氮年平均含量的6.20%。活性磷酸盐的年平均浓度为0.23μmol/dm3,浓度呈现春季较低和秋季较高的分布特征。活性硅酸盐的年平均浓度为2.86μmol/dm3,浓度呈现冬季较低和夏季较高的分布特征。DIN∶P,Si∶DIN和Si∶P的比值年平均分别为43.2,0.31和13.4,磷酸盐和硅酸盐为限制因素。与1983年在该海域所获数据比较发现,溶解无机氮的浓度是20年前的10.7倍,活性磷酸盐的浓度较20年前降低了43.9%,活性硅酸盐的浓度较20年前降低了34.1%。桑沟湾海区营养水平仍很低,总体上处于贫营养或中度营养化阶段,海水水质质量较好。     

胶州湾海水营养盐的分布及潜在性富营养化研究

根据2009年5、8、10月胶州湾海区3个航次海水营养盐的调查资料,分析了该海区海水营养盐的分布特征和时空变化,利用潜在富营养化评价模式评价水质营养状况。结果表明,溶解无机氮、活性磷酸盐以及活性硅酸盐的年均含量分别为0.335、0.028和0.725 mg/L,NO3-N是DIN的主要组成部分,占溶解无机氮含量的71.6%;8月营养盐含量高于5月和10月,营养盐的空间分布从东部河口区和北部养殖区两个高含量区向湾中心和湾口呈逐步递减之势;DIN∶P,Si∶DIN和Si∶P的比值年平均分别为53.9,2.03和57.7,活性磷酸盐为限制因素,胶州湾海域处于磷中等限制-磷限制潜在性富营养化,楼山河口和李村河口为中度营养-富营养,一旦有外界磷大量输入可能发生赤潮。     

加拿大海盆北部营养盐限制作用研究

利用2008年夏季中国第三次北极科学考察获得的营养盐、叶绿素a、温度和盐度等数据资料,结合现场营养盐添加实验的结果讨论西北冰洋加拿大海盆北部营养盐对浮游植物生长的限制作用。结果表明:由于融冰水稀释作用,加拿大海盆B80站约20m深度存在较强的盐跃层,阻碍了水体上下混合。较低浓度的溶解无机氮(DIN)和硅酸盐(分别为0.31μmol/L和0.94μmol/L)以及严重偏离Redfield比值的N/P、N/Si比值(分别为0.42和0.32)表明加拿大海盆表层水体存在N和Si限制。根据现场营养盐加富实验各培养组叶绿素a浓度变化、营养盐吸收总量差异和浮游植物种群结构,进一步表明氮是北冰洋海盆首要限制营养盐,而Si则抑制了硅质生物的生长。同时,较小的硝酸盐半饱和常数(Ks)证明即使在营养盐充足的情况下北冰洋海盆浮游植物生长速率也处于较低水平。计算得到各培养组营养盐吸收比例(N/P比值)均大于Redfield比值,可能是培养实验过程中以微型、微微型浮游植物为主,硅藻等小型浮游植物为辅造成的。     

夏季白令海海水二甲亚砜的分布及影响因素

基于中国第7次北极科学考察白令海现场调查资料与数据,分析了2016年夏季白令海海水颗粒态(DMSOp)和溶解态二甲亚砜(DMSOd)浓度的空间变化特征及其影响因素。研究表明,夏季白令海二甲亚砜(DMSO)浓度高于全球多数大洋和近岸海域。夏季白令海DMSOd和DMSOp浓度空间变化相似。表层海水DMSOp浓度为6.47～169.40 nmol/L,平均值为(79.62±56.10) nmol/L;DMSOd浓度的变化范围是20.07～153.70 nmol/L,平均值为(72.67±39.20) nmol/L。平面分布上,白令海表层DMSO浓度由海盆区、中外陆架区至内陆架区依次降低;垂直分布上由表至底随深度增加而降低,表层DMSOd和DMSOp浓度高于55 nmol/L,底层低于25 nmol/L。海盆区DMSOd主要源于DMS氧化和浮游生物直接合成的DMSOp,海盆区深层水团DMSOd浓度主要受控于温度和盐度。中外陆架区表层暖水团DMSO浓度主要受控于温度,陆架冷水团DMSO浓度则受盐度影响较大。内陆架区陆架水团DMSOp浓度和阿拉斯加沿岸水团DMSOd浓度分别受温度和DMS光化学氧化影响。     

长江口及邻近海区营养盐结构与限制

通过研究长江口及邻近海域溶解无机氮(DIN=NO₃-+NO₂-+NH₄+)、磷酸盐(PO₄3-)、硅酸盐(SiO₃2-)所表征的营养盐区域结构特征及影响因素,在分析营养盐绝对限制情况的基础上,划分了潜在相对营养限制区域。结果表明,123°E以西近岸表层区域DIN/P比值全年均高于16,而Si/DIN除秋季外基本小于1,显示出长江冲淡水影响下"过量氮"的特征。春夏季河口锋面区(31°~32.5°N,122.5°~124°E)硅藻的大量生长可使DIN/P异常升高和Si/DIN异常降低。秋季研究区域北部DIN/P西低东高且Si/DIN西高东低是由于在高DIN、低PO₄3-的长江冲淡水影响下,近岸受相对低DIN、高SiO₃2-的苏北沿岸流南下入侵影响而被分割而成。冬季长江口门东北部存在的高DIN/P和低Si/DIN区则主要由于寡营养盐的黑潮水深入陆架,向东北输送的部分长江冲淡水和增强的苏北沿岸流共同作用造成DIN升高所致。利用Redfield比值进行了不同站位表层潜在相对营养限制情况的区分。近岸123°E以西受高DIN、SiO₃2-长江冲淡水影响,四季多呈现PO₄3-潜在相对限制,而在春夏季由于浮游植物的大量吸收PO₄3-,造成局部PO₄3-绝对限制及潜在相对限制。春夏季氮限(DIN潜在相对限制)一般发生在外海部分站位,但较为零散。秋季除了东南外海大部分站位外,受苏北沿岸流影响在长江口北部近岸也存在氮限。随着低DIN/P的黑潮表层水(KSW)的入侵加强,冬季外海氮限站位增多。硅限(SiO₃2-潜在相对限制)在夏季发生在赤潮高发区,而冬季南部存在较多硅限站位表明KSW中SiO₃2-相对较为缺乏。     

春、秋季东、黄海营养盐的分布变化特征及营养结构

利用2000年10～11月和2001年3～4月的调查资料,分析讨论了春、秋季东、黄海营养盐的分布变化特征及营养结构状况。结果表明:该海域表层营养盐高值主要出现在长江冲淡水影响区和江浙近海海域,低值出现于东海陆架区和黄海西北部,黄海中部水域春、秋季因温跃层强弱不同表层营养盐含量差别较大。东、黄海海域春、秋季表层水N/P、Si/N和Si/P值(除秋季黄海北部局部水域N/P值小于10外)均远高于Redfield比值。春季东海海域N/P、Si/N和Si/P值明显高于黄海海域,并高于秋季;秋季黄海海域N/P、Si/N和Si/P值要高于东海海域,变化也大于春季。在强温跃层存在期间和浮游生物旺发季节,表层水域N/P、Si/N和Si/P值原本高的区域往往进一步升高,而温跃层较弱或浮游植物生长繁殖能力较弱的季节,表层水域N/P、Si/N和Si/P值将略有降低。东、黄海水域浮游植物光合作用受N限制的可能性极小,绝大部分水域主要是受P限制,Si的含量普遍较高,它不可能成为限制因子。长江冲淡水区和江浙近海海域过量的N及高N/P值特性且持续升高的趋势可能是近20年来这一地区富营养化程度加剧、赤潮频发的主要原因。     

黄海鳀鱼产卵场和越冬场营养盐分布特征

通过2002年11月、2003年1月和2004年6～7月的营养盐资料,讨论了黄海鳀鱼(Engraulis japoni-cus)产卵场和越冬场营养盐在秋、冬、夏三个季节分布变化特征.分析结果表明:黄海鳀鱼产卵场和越冬场表层营养盐随季节变化明显.秋季,营养盐在调查海区的南部出现最高值,向北递减,在朝鲜半岛沿岸浓度也较高;冬季,营养盐分布高值区出现在南黄海中部及朝鲜半岛西南近岸,表底层分布大致相同;夏季,在鳀鱼产卵场近岸形成了营养盐的高值区.在调查海域表层,PO43-和SiO32-分布冬季最高,秋季最低;DIN冬季最低,秋季最高.在底层,PO43-、SiO32-和DIN均是秋季最高,PO43-和DIN冬季高于夏季,而SiO32-则是夏季较高.对比了N/P,Si/N值,三个季节N/P值都大于Redfield值,尤其是夏季(50),Si/N值也略小于Redfield值.黄海鳀鱼产卵/越冬场浮游植物光合作用受N限制的可能性极小,绝大部分水域主要是受P限制,Si的含量普遍较高,它不可能成为限制因子.     

2012年长江口及其邻近海域营养盐分布的季节变化及影响因素

根据2012年3、5、8和12月4个航次长江口及邻近海域的调查数据,研究了氮、磷、硅营养盐及总氮(TN)、总磷(TP)的浓度特点,及其与盐度的相关性和叶绿素a的变化特征。结果表明,总溶解无机氮(DIN)、硅酸盐(Si O3)和TN的浓度分布均表现出自长江口至外海迅速降低的特征,且与盐度呈现显著负相关性。磷酸盐(PO4)的浓度降低程度随远离河口而减弱,且与盐度的相关性相对较弱,可能存在外海水补充;而TP则在长江口浑浊带海域呈现出较高浓度,且与盐度的相关性不明显,可能是受浑浊带泥沙吸附所致。在调查海区内,DIN与TN的平均值在夏季较低,结合叶绿素a数据分析,认为浮游植物吸收作用降低了DIN和TN的浓度。通过分析各营养盐之间的比值特征,进一步考察了营养盐来源及其对浮游植物生长的可能限制情况,其中N/P比值的变化同样揭示了N主要来自于长江水而P有部分来自于外海水的特征。该比值呈现远离河口而降低的特征,且在浑浊带无明显季节变化。春季和夏季有超过90%的调查站位显示潜在P限制,且均位于外海区。与历史资料对比发现,春季和夏季潜在P限制站位的比例明显升高,而潜在Si限制站位比例在春季和夏季降低。本文研究认为,营养盐含量及组成结构反映了该海域浮游植物群落组成和优势种的演替。     

西北冰洋中太平洋入流水营养盐的变化特征

利用1999,2003和2008年夏季(7-9月)三次中国北极科学考察数据资料,分析和讨论太平洋入流水营养盐的分布和楚科奇海关键生物地球化学过程对太平洋水化学性质的改造.结果表明,2003和2008年在白令海峡南部64.3°N纬向断面(BS断面)由于水团性质差异显著,营养盐呈西高、东低的分布趋势.2003年BS断面水柱...     

Relationship between phytoplankton composition and environmental factors in the surface waters of southern South China Sea in early summer of 2009

Horizontal distributions of phytoplankton abundance,species composition as well as environmental factors were investigated in the surface waters of southern South China Sea(SCS) in early summer(May 16 to June 7) of 2009.In most areas of southern SCS,the concentrations of nitrogen and phosphorus were very low and DIN/DIP ratios usually were lower than the Redfield N/P Ratio of 16:1.Nitrogen nutrients were significant lower in the upwelling region off Vietnam.A total of 144 taxa of phytoplankton were identified in the study area.The dominant genera were Prorocentrum,Gonyaulax,Gyrodinium,Scrippsiella and Chaetoceros,respectively.Spatial patterns of early-summer phytoplankton abundance and species composition should be mainly controlled by the upwelling off Vietnam and the discharge of Mekong River in the southern SCS.Diatoms dominated in the nutritious Mekong River Estuary or upwelling region off Vietnam;while dinoflagellates dominated in the oligotrophic pelagic region.The canonical correspondence analysis(CCA) indicates that most of diatoms favor higher levels of silicate and phosphorus,as well as lower temperature;while most of dinoflagellates favor the lower silicate and phosphorous and higher temperature.Correlation and CCA results indicate that silicate,nitrate and temperature were the most relevant environmental factors to regulate the horizontal pattern of early-summer phytoplankton in the surface waters of southern SCS.     

Spatial variability in the partial pressures of CO2 in the northern Bering and Chukchi seas

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.     

南海表层水中的溶解态Cu,Pb, Zn,Cd

于1998年“南海海洋环境调查”外业工作期间在南海的各个站位,按照严格的防沾污措施采集了106个表层海水样品.采用溶剂萃取-石墨炉原子吸收法对样品中的痕量重金属Cu,Pb,Zn,Cd含量进行了分析测试.测得各重金属的平均值如下:Cu 0.100 μg/dm3,Pb 0.060μg/dm3,Zn 0.086 μg/dm3,Cd 0.007μg/dm3,接近世界大洋水的浓度水平.各重金属的空间分布呈现出海区周边含量高于中央,浓度有自近岸向远海逐渐减小的趋势.相关分析的结果表明各重金属夏季相关性优于冬季,Cu与Cd存在良好的正相关关系,并且首次在南海表层水发现Cu,Cd与营养盐的相关关系.将重金属浓度值作数理统计分析,得到它们在南海的基线值.     

Dissolved Cu, Pb, Zn and Cd in the South China Sea surface waters

The understanding of the distribution of trace heavy metals in the world ocean has greatlyimProved in the past decades. But most of the data are of vertical profiles of certain stations(Bruland, l980; Paul et al., l992; RObert et al., l990) and large--scale study of temporaland spatial variability of trace heaVy metals in the ocean is rather few. In fact, affected by ver-tical mixing by upwelling or convection, biogenic removal, atmospheric fallout and continentalinput frorn rivers, the dist…     

Micro- and macronutrients in the southeastern Bering Sea: Insight into iron-replete and iron-depleted regimes

Surface transects and vertical profiles of macronutrients, dissolved iron (D-Fe), and dissolved manganese (D-Mn) were investigated during August 2003 in the southeastern Bering Sea. We observed iron-limited, HNLC surface waters in the deep basin of the Bering Sea (15-20 μmol/kg nitrate, ∼0.07 nmol/kg D-Fe, and ?1.0 nmol/kg D-Mn); nitrate-limited, iron-replete surface waters over the shelf (<0.1 μmol/kg nitrate, 0.5-4 nmol/kg D-Fe, and 2-33 nmol/kg D-Mn); and high biomass at the shelf break (“Green Belt”), where diatoms appeared to have been stressed by low D-Fe concentrations (<0.3 nmol/kg). Sources of nitrate and iron to the Green Belt were investigated. A mixture of Aleutian North Slope Current water (with elevated, but non-sufficient iron concentrations relative to its high nitrate concentrations) and surface waters from the vicinity of the Bering Canyon (with lower nitrate concentrations, but similar dissolved iron concentrations) was carried along the shelf break by the Bering Slope Current. This water mixture provided macro- and micronutrients at the southern end of the shelf break. The oceanic domain supplied additional macronutrients to Green Belt waters, while the bottom layer of the outer shelf domain supplied additional macro- and micronutrients through enhanced vertical mixing at the shelf break. Surface waters near the Pribilof Islands, where the highest surface D-Fe concentrations were observed (∼5-6 nmol/kg), represent a potential source of additional iron to Green Belt waters. During summer, the subsurface water of the middle shelf domain is a potential source of nitrate to the nitrate depleted waters of the shelf. In this subsurface cool pool, we observed evidence of substantial denitrification with lower than expected nitrate concentrations.     

Structure and resilience of overwintering habitats of Calanus finmarchicus in the Eastern Norwegian Sea

Very high concentrations of overwintering Calanus finmarchicus were found in the eastern Lofoten Basin of the Norwegian Sea close to the shelf break in January 2001–2002. A coupled 3D hydrodynamic and ecological model was used to study the formation of this deep overwintering aggregation and its stability. The ecological model includes nutrients, phytoplankton and microzooplankton in addition to a stage-structured model of C. finmarchicus. Using a Eulerian approach, the model was initiated with an overwintering stock evenly distributed in the oceanic regions of the Norwegian Sea, i.e. where depths>600 m. Spawning and development of the new generation take place in response to vertical mixing and phytoplankton development. Animals are assumed to begin their descent to overwintering depths of 700–1000 m as late stage Vs. Model results show that, in late summer, high concentrations of animals were found at overwintering depths near the shelf break north of the North Sea, off the northeastern Vøring Plateau and in the eastern Lofoten Basin along the slope of the Barents Sea shelf. They remained there for months due to deep eddies and southward, deep currents along the Norwegian shelf. The simulation experiments indicate that the combined effect of deep anticyclonic circulation and vertical migration behavior of the animals may explain the high concentrations of overwintering C. finmarchicus found in field surveys in the Eastern Lofoten Basin, close to the shelf break.     

Phytoplankton community in the Western Arctic in July–August 2003

The phytoplankton community was studied in Bering Strait and over the shelf, continental slope, and deep-water zones of the Chukchi and Beaufort seas in the middle of the vegetative season (July–August 2003). Its structure was analyzed in relation to ice conditions and the seasonal patterns of water warming, stratification, and nutrient concentrations. The overall ranges of variation in phytoplankton abundance and biomass were estimated at 2.0 × 10² to 6.0 × 10⁶ cells/l and 0.1 to 444.1 mg C/m³. The bulk of phytoplankton cells concentrated in the seasonal picnocline, at depths of 10–25 m. The highest values of cell density and biomass were recorded in regions influenced by the inflow of Bering Sea waters or characterized by intense hydrodynamics, such as the Bering Strait, Barrow Canyon, and the outer shelf and slope of the Chukchi Sea. In the middle of the vegetative season, the phytoplankton in the study region of the Western Arctic proved to comprise three successional (seasonal) assemblages, namely, the early spring, late spring, and summer assemblages. Their spatial distribution was dependent mainly on local features of hydrological and nutrient regimes rather than on general latitudinal trends of seasonal succession characteristic of arctic ecosystems.