Seasonal variations of dimethylsul.de (DMS) and dimethylsulfoniopropionate (DMSP) in the sea-surface microlayer and subsurface water of Jiaozhou Bay and its adjacent area

The distributions of DMS and its precursor dimethylsulfoniopropionate, in both dissolved (DMSPd) and particulate fractions (DMSPp) were determined in the sea-surface microlayer and corresponding subsurface water of the Jiaozhou Bay, China and its adjacent area in May and August 2006. The concentrations of all these components showed a clear seasonal variation, with higher concentrations occurring in summer. This can be mainly attributed to the higher phytoplankton biomass observed in summer. Simultaneously, the enrichment extents of DMSPd and DMSPp in the microlayer also exhibited seasonal changes, with higher values in spring and lower ones in summer. Higher water temperature and stronger radiant intensity in summer can enhance their solubility and photochemical reaction in the microlayer water, reducing their enrichment factors (the ratio of concentration in the microlayer to that in the corresponding subsurface water). A statistically signi.cant relationship was found between the microlayer and subsurface water concentrations of DMS, DMSP and chlorophyll a, demonstrating that the biogenic materials in the microlayer come primarily from the underlying water. Moreover, our data show that the concentrations of DMSPp and DMS were signi.cantly correlated with the levels of chlorophyll a, indicating that phytoplankton biomass might play an important role in controlling the distributions of biogenic sulfurs in the study area. The ratios of DMS/chlorophyll a and DMSPp/chlorophyll a varied little from spring to summer, suggesting that there was no obvious change in the proportion of DMSP producers in the phytoplankton community. The mean sea-to-air .ux of DMS from the study area was estimated to be 5.70 μmol/(m2 ·d), which highlights the e.ects of human impacts on DMS emission.     

Biogeochemistry of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) in the surface microlayer and subsurface water of the western North Atlantic during spring

Sixteen surface microlayer samples and corresponding subsurface water samples were collected in the western North Atlantic during April–May 2003 to study the distribution and cycling of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) and the factors influencing them. In the surface microlayer, high concentrations of DMS appeared mostly in the samples containing high levels of chlorophyll a, and a significant correlation was found between DMS and chlorophyll a concentrations. In addition, microlayer DMS concentrations were correlated with microlayer DMSPd (dissolved) concentrations. DMSPd was found to be enriched in the microlayer with an average enrichment factor (EF) of 5.19. However, no microlayer enrichment of DMS was found for most samples collected. Interestingly, the DMS production rates in the microlayer were much higher than those in the subsurface water. Enhanced DMS production in the microlayer was likely due to the higher concentrations of DMSPd in the microlayer. A consistent pattern was observed in this study in which the concentrations of DMS, DMSPd, DMSPp (particulate) and chlorophyll a in the microlayer were closely related to their corresponding subsurface water concentrations, suggesting that these constituents in the microlayer were directly dependent on the transport from the bulk liquid below. Enhanced DMS production in the microlayer further reinforces the conclusion that the surface microlayer has greater biological activity relative to the underlying water.     

Experimental studies on dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) production by four marine microalgae

The production of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) by marine microalgae was investigated to elucidate more on the role of marine phytoplankton in ocean-atmosphere interactions in the global biogeochemical sulfur cycle.Axenic laboratory cultures of four marine microalgae–Isochrysis galbana 8701,Pavlova viridis,Platymonas sp.and Chlorella were tested for DMSP production and conversion into DMS.Among these four microalgae,Isochrysis galbana 8701 and Pavlova viridis are two species of Haptophyta,while Chlorella and Platymonas sp.belong to Chlorophyta.The results demonstrate that the four algae can produce various amounts of DMS(P),and their DMS(P) production was species specific.With similar cell size,more DMS was released by Haptophyta than that by Chlorophyta.DMS and dissolved DMSP (DMSPd) concentrations in algal cultures varied significantly during their life cycles.The highest release of DMS appeared in the senescent period for all the four algae.Variations in DMSP concentrations were in strong compliance with variations in algal cell densities during the growing period.A highly significant correlation was observed between the DMS and DMSPd concentrations in algal cultures,and there was a time lag for the variation trend of the DMS concentrations as compared with that of the DMSPd.The consistency of variation patterns of DMS and DMSPd implies that the DMSPd produced by phytoplankton cells has a marked effect on the production of DMS.In the present study,the authors’ results specify the significant contribution of the marine phytoplankton to DMS(P) production and the importance of biological control of DMS concentrations in oceanic water.     

2010年夏、秋季胶州湾浮游动物对表层海水中DMS分布的影响

于2010年7~11月对胶州湾夏、秋季浮游动物种类和丰度进行现场调查,并分析讨论了胶州湾夏、秋季浮游动物丰度的水平分布与环境因子(温度、盐度、水深、叶绿素a)和二甲基硫(DMS)、溶解态β-二甲基巯基丙酸内盐(DMSPd)、颗粒态β-二甲基巯基丙酸内盐(DMSPp)的相关性。结果表明,胶州湾浮游动物丰度分布不均匀,8月湾内西部沿岸海域C1站位出现调查期间的动物丰度最大值(656.1ind/m3),最小值(1.492ind/m3)出现在10月胶州湾东北部的A2站位。浮游动物丰度具有明显的季节变化,秋季浮游动物丰度低于夏季浮游动物丰度。浮游动物丰度与盐度、叶绿素a含量、细菌生物量的相关性不明显,2010年10月浮游动物丰度与DMS呈显著正相关(P0.05),11月的浮游动物丰度与DMSPp呈显著正相关(P0.05),其它月份(7、8、9月)的浮游动物丰度与DMS、DMSPd、DMSPp浓度的相关性均不明显。由于浮游动物摄食活动对DMS释放的影响受多种因素的制约,因此浮游动物与DMS的相互作用需要进一步研究。     

胶州湾海水中DMS和DMSP的分布及其影响因素

为了解人为活动对二甲基硫(DMS)和二甲巯基丙酸(DMSP)生物生产的干扰,分别于2005年8月、11月对胶州湾海域进行采样。测定结果表明:胶州湾海水中8月DMS、DMSPd和DMSPp在次表层的平均含量分别为4.89,17.9和23.93nmol·L-1,在微表层中的平均含量分别为4.58,19.98和21.49nmol·L-1,11月DMS、DMSPd和DMSPp在次表层的平均含量分别为2.07,12.99和16.74nmol·L-1,在微表层中的平均含量分别为1.44,16.13和19.62nmol·L-1。DMS和DMSP的水平分布由于受到陆源输入的影响,呈现出自湾内向湾外递降的趋势。DMS和DMSP的含量夏季高于秋季。DMS和Chl-a在每个季节具有一定的相关性。DMS浓度的增加导致DMS通量增加。对海水微表层和次表层的研究表明,DMS和DMSPp并未在微表层中富集,而DMSPd有一定程度的富集。DMS,DMSP,Chl-a在海水微表层和次表层之间浓度分布的相关性体现了2层水体之间存在强烈的交换作用。     

Simple determination of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) using solid-phase microextraction and gas chromatography-mass spectrometry

Solid-phase microextraction (SPME) is a simple, sensitive and less destructive method for the determination of dimethylsulfide (DMS) in seawater. Combined with detection by gas chromatography-mass spectrometry (GC-MS), the method had sufficient sensitivity (minimum detectable concentration of DMS was 0.05 nM), and practical levels of reproducibility (relative standard deviation ≤7%) and linearity (r ² > 0.995) over a wide concentration range (0.5 to 910 nM). The protocol developed was applied to a Sagami Bay water sample to determine concentrations of DMS and DMSP, and in situ DMSP-lyase activity.     

大亚湾微表层和次表层海水营养盐的研究

根据1998年秋季（10、11月）、1999年春、秋季（4、5、10月）5个航次对大亚湾海区微、次表层的调查结果，分析了微表层海水对氮、磷、硅营养盐的富集概况，讨论了营养盐与环境因子的关系。结果表明：大亚湾海区微表层海水对氮、磷、硅营养盐均有富集作用，因海况及季节不同，富集因数（EF）与其他海区的有所差别；无论夏季或秋季，大亚湾海区微表层海水中无机氮都以NH4－N为主要存在形态；其余水层则以NO3－N为主要存在形态。结果还表明，微表层、次表层海水中NH4－N与BOD5、COD测值都呈高度显著正相关，与PO4－P和SiO3-Si含量均无相关，说明大亚湾海区水中含氮有机物较含磷有机物丰富。     

Chemical properties of colored dissolved organic matter in the sea-surface microlayer and subsurface water of Jiaozhou Bay, China in autumn and winter

The distribution and chemical properties of chromophoric dissolved organic matter (CDOM) in the Jiaozhou Bay, China were examined during four cruises in 2010-2011. The influence of freshwater and industrial and municipal sewage along the eastern coast of the bay was clearly evident as CDOM levels (defined as a 305 ), and dissolved organic carbon (DOC) concentrations were well correlated with salinity during all the cruises. Moreover, DOC concentrations were significantly correlated with chlorophyll a concentrations in the surface microlayer as well as in the subsurface water. The concentrations of DOC and CDOM displayed a gradually decreasing trend from the northwestern and eastern coast to the central bay, and the values and gradients of their concentrations on the eastern coast were generally higher than those on the western coast. In addition, CDOM and DOC levels were generally higher in the surface microlayer than in the subsurface water. In comparison with DOC, CDOM exhibited a greater extent of enrichment in the microlayer in each cruise, with average enrichment factor (E F ) values of 1.38 and 1.84, respectively. Four fluorescent components were identified from the surface microlayer and subsurface water samples and could be distinguished as peak A, peak T, peak B and peak M. For all the cruises, peak A levels were higher in the surface microlayer than in the subsurface water. This pattern of variation might be attributed to the terrestrial input.     

青岛沿岸海区海藻体中DMSP含量测定

实验研究海藻体中二甲基硫基丙酸酯（Ｄｉｍｅｔｈｙｌｓｕｌｆｏｎｉｕｍｐｒｏｐｉｏｎａｔｅ,ＤＭＳＰ）的简单测定方法。改进顶空进样方法灵敏度低的缺点,采用碱解和萃取吸收同时进行气相色谱火焰光度检测法测定不同种类的底栖藻中所含的ＤＭＳＰ。并以此测定不同季节胶州湾部分地区近岸表层水体浮游藻所含的ＤＭＳＰ,同时还测定水体中的磷酸盐浓度。结果表明在底栖藻中ＤＭＳＰ含量随季节呈现一定的规律性变化,不同藻体内ＤＭＳＰ含量相差可达两个数量级,而单位水体微藻中的ＤＭ－ＳＰ亦随季节呈现一定的规律性变化     

胶州湾及青岛近海微表层与次表层中二甲基硫(DMS)与二甲巯基丙酸(DMSP)的浓度分布

以胶州湾及青岛近海为研究区域,利用吹扫-捕集气相色谱法研究了二甲基硫(DMS)和二甲巯基丙酸(DMSP,分为溶解态DMSPd和颗粒态DMSPp)在微表层与次表层中的浓度以及它们在微表层中的富集行为。结果表明,DMS、DMSPd和DMSPp在微表层中的浓度高于次表层,它们在微表层中的富集因子分别为1.17、1.84和1.51。研究发现,DMS及DMSPp浓度与叶绿素a(Chl-a)浓度有很好的相关性,但它们的周日变化与Chl-a并不完全同步。DMS/Chl-a和DMSPp/Chl-a的比值在次表层和微表层分别为4.35、13.47mmol/g和3.99、15.88mmol/g。胶州湾及青岛近海生态环境受人为活动干扰严重,使本海域DMS含量较高,从而贡献出较大的DMS海-气通量。     

Seasonal variations in dimethylsulfoniopropionate and dimethylsulfide concentrations in relation to the plankton community in the St. Lawrence Estuary

Weekly variations in total dimethylsulfoniopropionate (DMSPt) and dimethylsulfide (DMS) were investigated in relation to the phytoplankton assemblage from spring to fall 1994 at a coastal fixed station in the St. Lawrence Estuary. DMSPt and DMS concentrations showed a strong seasonality and were tightly coupled in time. Maximum concentrations of DMSPt and DMS were observed in July and August, during a period of warm water and low nutrient concentrations. Seasonal maxima of 365.4 nmol l⁻¹ for DMSPt and 14.2 nmol l⁻¹ for DMS in early August coincided with the presence of many phytoplankton species, such as Alexandrium tamarense, Dinophysis acuminata, Gymnodinium sp., Heterocapsa rotundata, Protoperidinium ovatum, Scrippsiella trochoidea, Chrysochromulina sp. (6 μm), Cryptomonas sp. (6 μm), a group of microflagellates smaller than 5 μm (mf < 5), many tintinnids, and Mesodinium rubrum. The abundance of mf < 5 followed the general trend of DMS concentrations. The temporal occurrence of high P. ovatum abundance and DMSPt concentrations suggests that this heterotrophic dinoflagellate can either synthesize DMSP or acquire it from DMSP-rich prey. The calculated sea-to-air DMS flux reached a maximum of 8.36 μmol ⁻² d⁻¹ on August 1. The estimated annual emission from the St. Lawrence Estuary is 77.2 tons of biogenic sulfur to the atmosphere.     

Factors determining the vertical profile of dimethylsulfide in the Sargasso Sea during summer

The major source of reduced sulfur in the remote marine atmosphere is the biogenic compound dimethylsulfide (DMS), which is ubiquitous in the world's oceans and released through food web interactions. Relevant fluxes and concentrations of DMS, its phytoplankton-produced precursor, dimethylsulfoniopropionate (DMSP) and related parameters were measured during an intensive Lagrangian field study in two mesoscale eddies in the Sargasso Sea during July–August 2004, a period characterized by high mixed-layer DMS and low chlorophyll—the so-called ‘DMS summer paradox’. We used a 1-D vertically variable DMS production model forced with output from a 1-D vertical mixing model to evaluate the extent to which the simulated vertical structure in DMS and DMSP was consistent with changes expected from field-determined rate measurements of individual processes, such as photolysis, microbial DMS and dissolved DMSP turnover, and air–sea gas exchange. Model numerical experiments and related parametric sensitivity analyses suggested that the vertical structure of the DMS profile in the upper 60 m was determined mainly by the interplay of the two depth-variable processes—vertical mixing and photolysis—and less by biological consumption of DMS. A key finding from the model calibration was the need to increase the DMS(P) algal exudation rate constant, which includes the effects of cell rupture due to grazing and cell lysis, to significantly higher values than previously used in other regions. This was consistent with the small algal cell size and therefore high surface area-to-volume ratio of the dominant DMSP-producing group—the picoeukaryotes.     

Study on the analysis and distribution of dimethylsulfoxide in the Jiaozhou Bay

A chemoreduction-purge-and-trap gas chromatographic method has been developed for the determination of trace dimethylsulfoxide (DMSO) in seawater. In the analysis procedure, DMSO was first reduced to dimethylsufide (DMS) by sodium borohydride and then the produced DMS was analyzed using the purge-and-trap technique coupled with gas chromatographic separation and flame photometric detection. Under the optimum conditions, 97% DMSO was reduced in the standard solution samples with a standard deviation of 5% (n=5). The detection limit of DMSO was 2.7 pmol of sulfur, corresponding to a concentration of 0.75 nmol/L for a 40 ml sample. This method was applied to determine the dissolved DMSO (DMSOd) and particulate DMSO (DMSOp) concentrations in the surface seawater of the Jiaozhou Bay, and the results showed that the DMSOd and DMSOp concentrations varied from 16.8 to 921.1 nmol/L (mean:165.2 nmol/L) and from 8.0 to 162.4 nmol/L (mean:57.7 nmol/L), respectively. The high concentrations of DMSOp were generally found in productive regions. Consequently, a significant correlation was found between the concentrations of DMSOp and chlorophyll a, suggesting that phytoplankton biomass might play an important role in controlling the distribution of DMSOp in the bay. Moreover, in the study area, the concentrations of DMSOd were significantly correlated with the levels of DMS, implying that the production of DMSOd is mainly via photochemical and biological oxidation of DMS.     

Biological control of short-term variations in the concentration of DMSP and DMS during a Phaeocystis spring bloom

In the spring of 1995, short-term variations in the concentration of particulate and dissolved dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) were monitored in the western Wadden Sea, a shallow coastal region in open connection with the North Sea. Significant correlations were found between abundance of Phaeocystis globosa and particulate DMSP; concentrations increased rapidly from 100 to 1650 nM in the middle of April. Highest DMS concentrations were found during the initial phase of the exponential growth of the bloom. DMS production and loss rates of DMSP and DMS were estimated experimentally during various phases of the bloom. DMS production and consumption were roughly in balance, with production only slightly exceeding consumption at the start of the bloom. Rates of production and consumption were highest during the exponential growth phase of Phaeocystis and declined in the course of the bloom (from 300–375 to less than 5 nmol dm⁻³ d⁻¹). Demethylation of DMSP increased during the bloom (from 11 to 1300 nmol dm⁻³ d⁻¹); it accounted for up to 100% of the DMSP loss at the end of the bloom. The shift from DMSP cleavage to demethylation in the course of a Phaeocystis bloom implies that DMS concentrations are not necessarily highest at the peak or towards the end of blooms.     

春秋季南黄海二甲基硫(DMS)与二甲巯基丙酸(DMSP)的浓度分布研究

Temporal distributions of dimethylsulfide(DMS) and dimethylsulfoniopropionate(DMSP) were studied in the southern Yellow Sea(SYS) during April and September 2010. The mean concentrations(range) of DMS, dissolved and particulate DMSP(DMSPd and DMSPp) in the surface waters in spring are 1.69(0.48–4.92), 3.18(0.68–6.75)and 15.81(2.82–52.33) nmol/L, respectively, and those in autumn are 2.80(1.33–5.10), 5.45(2.19–11.30) and 30.63(6.24–137.87) nmol/L. On the whole, the distributions of DMS and DMSP in spring are completely different from those in autumn. In the central part of the SYS, the concentrations of DMS and DMSP in spring are obviously higher than those in autumn, but the opposite situation is found on the south of 34°N, which can be attributed to the differences in nutrients and phytoplankton biomass and composition between spring and autumn. Besides,the seasonal variations of water column stability and the Changjiang diluted water also have significant impact on the distributions of DMS and DMSP in spring and autumn on the south of 34°N. DMS and DMSPp concentrations coincide well with chlorophyll a(Chl a) levels in the spring cruise, suggesting that phytoplankton biomass may play an important role in controlling the distributions of DMS and DMSPp in the study area. Annual DMS emission rates range from 0.015 to 0.033 Tg/a(calculated by S), respectively, using the equations of Liss and Merlivat(1986) and Wanninkhof(1992). This result implies a significant relative contribution of the SYS to the global oceanic DMS fluxes.     

胶州湾浮游病毒的分布研究

运用荧光显微镜技术,对2007年6～8月胶州湾14个站点的浮游病毒丰度进行了检测,分析了病毒在不同月份的水平与垂直分布变化,发现胶州湾浮游病毒的丰度在0.48×107～22.78×107个/mL之间,平均值为(5.72±4.72)×107个/mL,7月份病毒丰度明显高于其他两个月(P0.01)。病毒呈现从湾内至湾口至湾外递减的趋势,病毒垂直分布变化不明显。病毒-细菌比率(VBR)范围为3.90～150.72,平均值42.05±28.55,处于较高水平。利用多元相关性分析发现,病毒丰度与异养细菌丰度、聚球藻蓝细菌丰度和叶绿素a含量相关,其相关系数r分别为0.605(P0.01),0.265(P0.01)和0.604(P0.05),确定系数R2分析表明,异养细菌和叶绿素a对浮游病毒丰度的影响基本相当。病毒丰度与温度、盐度无明显相关性。对VBR的分析表明,调查区域藻类病毒占总浮游病毒的比例较高;通过VBR与异养细菌丰度的负相关性分析,认为胶州湾噬菌体的宿主菌种群较单一。     

秋季东海二甲基硫和二甲巯基丙酸内盐浓度分布及降解速率研究

于2013年10~11月现场测定了东海中二甲基硫(DMS)及其前体物质二甲巯基丙酸内盐(DMSP,分为溶解态DMSPd和颗粒态DMSPp)的含量,研究其水平分布特征、DMSPp的粒径分布及DMSPd的降解速率,并对DMS的海-气交换通量进行了探讨。研究结果表明,表层海水中DMS、DMSPd和DMSPp的浓度平均值分别为(4.84±0.40)、(5.84±0.93)和(13.01±0.52)nmol·L-1。海水中DMSPd的降解速率在2.59~16.36nmol·L-1·d-1之间,平均值为(6.78±0.84)nmol·L-1·d-1。调查海域范围内,小型浮游植物(20μm)是DMSPp和叶绿素a(Chl a)重要贡献者。此外,秋季东海表层海水DMS的海-气交换通量为0.66~31.73μmol·m-2·d-1,平均值为(11.63±0.71)μmol·m-2·d-1。     

Spatial distributions and seasonal variations of particulate phosphorus in the Jiaozhou Bay in North China

Based on the measurements of particulate phosphorus(PP) in the Jiaozhou Bay from May 2003 to April 2004,the spatial distribution,seasonal variation and biogeochemical characteristics of PP were investigated to understand the fates and roles of phosphorus in the Jiaozhou Bay ecosystem.The concentration of the total PP ranged from 0.07 to 2.09 μmol/dm3.The concentration of POP was from 0.01 to 1.83 μmol/dm3,with an average of 0.32 μmol/dm3,which accounted for 49.6% in total PP.The concentration of PIP was fro...     

胶州湾海域5种粗毛猛水蚤的形态记述

粗毛猛水蚤科（Miraciidae Dana,1846）是猛水蚤目（Harpacticoida Sars,1903）种类数目居于第二的科,分布广泛,栖息环境多样。本文通过对2008年在胶州湾海域采集的沉积物进行离心提取,经解剖和形态分类学方法鉴定,鉴定粗毛猛水蚤科5属5种。其中,田园威伦狭腹猛水蚤（Willenstenhelia thalia Karanovic&Kim K.,2014）为我国海域的首次记录。文中还对胶州湾已发现的底栖粗毛猛水蚤制定了检索表。     

海洋中二甲基硫的生物生产与消费过程

DMS是海洋中最主要的挥发性有机硫化物,对全球气候变化和环境酸化产生重要影响。DMS的生物生产与消耗主要发生在海洋真光层。生物的生产与消耗被认为是海洋中DMS的主要来源和去除途径。海洋中DMS的生物生产和消耗是密切相关的,两者的速率基本保持平衡。目前,有关DMS生物生产与消费速率的测定方法有放射性同位素示踪和加抑制剂2种,后者颇受青睐,不过有关抑制机理还需进一步的研究。