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1.
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   

2.
Spatial variations in dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) were surveyed in the surface microlayer and in the subsurface waters of the low productivity South China Sea in May 2005. Overall, average subsurface water concentrations of DMS and DMSP of dissolved (DMSPd) and particulate (DMSPp) fractions were 1.74 (1.00-2.50), 3.92 (2.21-6.54) and 6.06 (3.40-8.68) nM, respectively. No enrichment in DMS and DMSPp was observed in the microlayer. In contrast, the microlayer showed a DMSPd enrichment, with an average enrichment factor (EF, defined as the ratio of the microlayer concentration to subsurface water concentration) of 1.40. In the study area, none of the sulfur components were correlated with chlorophyll a. An important finding in this study was that DMS, DMSP and chlorophyll a concentrations in the surface microlayer were respectively correlated with those in the subsurface water, suggesting a close linkage between these two water bodies. The ratios of DMS:Chl-a and DMSPp:Chl-a showed a gradually increasing trend from North to South. This might be due to changes in the proportion of DMSP producers in the phytoplankton community with the increased surface seawater temperature. A clear diurnal variation in the DMS and DMSP concentrations was observed at an anchor station with the highest concentrations appearing during the day and the lowest concentrations during the night. The higher DMS and DMSP concentrations during daytime might be attributed to the light-induced increase in both algal synthesis and exudation of DMSP and biological production of DMS. The mean flux of DMS from the investigated area to the atmosphere was estimated to be 2.06 micromo lm(-2)d(-1). This low DMS emission flux, together with the low DMS surface concentrations was attributed to the low productivity in this sea.  相似文献   

3.
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.  相似文献   

4.
海水温度对衰亡期浒苔释放生源硫影响的模拟研究   总被引：1，自引：0，他引：1  
韩露  邓雪  李培峰  高先池  刘春颖 《海洋学报》2018,40(10):110-118
为研究浒苔释放生源硫的特征,本文对采集于黄海绿潮中期和末期的浒苔进行了实验室模拟培养,探讨了不同温度对衰亡期浒苔释放生源硫化物的影响。实验结果表明,在10~25℃温度范围内,温度升高能够加速浒苔的衰亡。二甲基硫（DMS）的平均释放速率范围为2.79~150.70 nmol/（L·g·d）,二甲基硫基丙酸内盐（DMSP）的平均释放速率范围为2.16~113.26 nmol/（L·g·d）。温度升高能够使DMS和DMSP的释放速率加快,释放量增加,DMS最大平均释放速率在25℃条件下比10℃条件下升高了约60%,培养液中DMS浓度升高了2~3倍。采集于绿潮末期的浒苔培养液中的DMS和DMSP和采集于绿潮中期的浒苔相比,浓度有所增加,采集于浒苔绿潮末期浒苔培养液中DMS的最高平均浓度为418.41 nmol/L,约为中期的4倍;DMSP的最高平均浓度为316.14 nmol/L,是中期的3倍。浒苔绿潮的爆发会对水体中的硫体系循环产生影响,进而影响该海域生态环境。  相似文献   

5.
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.  相似文献   

6.
塔玛亚历山大藻生成二甲基硫和二甲基硫丙酸的实验研究   总被引：2，自引：0，他引：2  
主要研究在封闭培养条件下塔玛亚历山大藻（Alexandrium tamarense)生长周期内藻体细胞的二甲基硫丙酸（DMSP（）含量以及释放至水体的二甲基硫（DMS）含量，结果表明：（1）塔玛亚历山大藻藻体细胞DMSP含量变化与该藻细胞数量动态变化趋势相一致，在生长周期的第7天最高值；（2）藻体细胞的DMSP含量以及释放至水体的DMS含量均与藻体细胞数量有显著相关；（3）单位细胞DMSP生成量的变化与DMS释放量变化呈现相反的趋势，在DMS释放量最高时，单位细胞DMSP生成量最低。  相似文献   

7.
于2012年7—9月现场测定了北极挪威海和格陵兰海区域海水二甲基硫(DMS)及其前体物质二甲巯基丙酸内盐(DMSP,分溶解态DMSPd和颗粒态DMSPp)的含量,研究了其空间分布格局及其影响因素,探讨了表层海水DMS的生物周转和去除途径。结果表明,表层海水DMS、DMSPd和DMSPp的平均浓度分别为5.36nmol/L、15.63nmol/L和96.73nmol/L,受挪威海流和北极深层水影响,表层海水二甲基硫化物浓度呈现出由低纬度向高纬度海域递减的趋势。DMSPd和DMSPp浓度与Chl a浓度均有显著的相关性,说明浮游植物生物量是影响挪威海和格陵兰海二甲基硫化物生产的重要因素。表层海水DMS生物生产和消费速率平均值分别为18.19nmol/(L·d)、15.67nmol/(L·d)。DMS微生物周转时间变化范围为0.03~1.80d,平均值为0.49d,DMS海-气周转时间是微生物消费时间的90倍,说明夏季挪威海和格陵兰海表层海水中DMS微生物消费过程是比海-气扩散更具优势的去除机制。  相似文献   

8.
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.  相似文献   

9.
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.  相似文献   

10.
High concentrations of the phytoplankton metabolite dimethylsulfoniopropionate (DMSP) and its degradation product dimethylsulfide (DMS) are associated with blooms of Phaeocystis antarctica in the Ross Sea, Antarctica. Episodic and rapid vertical export of Phaeocystis biomass to deep water has been reported for the Ross Sea, therefore we examined the distribution and microbial consumption rates of DMSP and DMS throughout the sub-euphotic water column. Total DMSP (dissolved+particulate; DMSPt) was present at 0.5–22 nM at depths between 70 and 690 m during both the early bloom (November) and the late bloom (January). Sub-euphotic peaks of DMSP were sometimes associated with mid-water temperature maxima, and elevated DMSP below 70 m was found mainly in water masses characterized as Modified Circumpolar Deep Water or Antarctic Shelf Water. Overall, 50–94% of the integrated water-column DMSPt was found below the euphotic zone. At one station during the early bloom, local maxima of DMSPt (14 nM) and DMS (20 nM) were observed between 113 and 240 m and these maxima corresponded with high chlorophyll a concentrations, P. antarctica cell numbers, and Fv/Fm (the quantum yield of photosystem II). During the late bloom, a sub-euphotic maximum of DMSPt (15.8 nM) at 250 m cooccurred with peaks of chlorophyll a concentration, DMSP lyase activity, bacterial production and dissolved DMSP consumption rates. DMSP turnover contributed ～12% of the bacterial carbon demand between 200 and 400 m. DMS concentrations peaked at 286 m but the maximum concentration (0.42 nM) was far lower than observed during the early bloom, probably because of relatively rapid biological consumption of DMS (1–3 turnovers per day) which, in turn, contributed to elevated dissolved dimethylsulfoxide (DMSO) concentrations. Relatively stable DMSPt distributions at some sites suggest that rapid sinking of Phaeocystis biomass is probably not the major mechanism responsible for mesopelagic DMSP accumulations. Rather, subduction of near-surface water masses, lateral advective transport or trapping of slowly sinking P. antarctica biomass in intermediate water masses are more likely mechanisms. We found that a culture of P. antarctica maintained cellular integrity during 34 days of darkness, therefore the presence of intact cells (and DMSP) at depth can be explained even under a slow sinking/advection scenario. Whatever the mechanism, the large pools of DMSP and DMS below the euphotic zone suggest that export exerts a control on potential DMS emission from the surface waters of the Ross Sea.  相似文献   

11.
We report here dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) levels as a function of plankton communities and abiotic factors over a 12-month cycle in the Mediterranean oligotrophic coastal and shallow ecosystem of Niel Bay (N.W. Mediterranean Sea, France). Total particulate DMSP (DMSPp) and DMS concentrations were highly seasonal, peaking during a spring (April) bloom at 8.9 nM and 73.9 nM, respectively. Significant positive correlations were found between total DMSPp concentration and the abundance or biomass of the dinoflagellate Prorocentrum compressum (Spearman's rank correlation test: r = 0.704; p = 0.011). Similarly, DMS concentrations peaked during the development of blooms of P. compressum and Gymnodinium sp. There seemed to be a positive relationship between the chlorophyll a to pheopigment ratio and DMS concentrations, suggesting that DMS was released during phytoplankton growth. High DMS levels recorded in the shallow Niel Bay may also result from the activity of benthic macroalgae, and/or macrophytes such as Posidonia spp., or the resuspension of sulfur species accumulating in sediments. The fractionation of particulate DMSP into three size classes (>90 μm, 5–90 μm and 0.2–5 μm) revealed that 5–90 μm DMSP-containing particles made the greatest contribution to the total DMSPp pool (annual mean contribution = 62%), with a maximal contribution in April (96%). This size class consisted mainly of dinoflagellates (annual mean contribution = 68%), with P. compressum and Gymnodinium sp. the predominant species, together accounting for up to 44% of the phytoplankton present. The positive correlation between DMSP concentration in the 5–90 μm size class and the abundance of P. compressum (Spearman's rank correlation test: r = 0.648; p = 0.023) suggests that this phytoplankton species would be the major DMSP producer in Niel Bay. The DMSP collected in the >90 μm fraction was principally associated with zooplankton organisms, dominated by copepods (nauplii and copepodites). DMSP>90, not due to a specific zooplankton production, resulted from the phytoplankton cells ingested during grazing. The concomitant peaks of DMS concentration and zooplankton abundance suggest that zooplankton may play a role in releasing DMSP and/or DMS through sloppy feeding.  相似文献   

12.
Lagrangian time series of dimethylsulfide (DMS) concentrations from a cyclonic and an anticyclonic eddy in the Sargasso Sea were used in conjunction with measured DMS loss rates and a model of vertical mixing to estimate gross DMS production in the upper 60 m during summer 2004. Loss terms included biological consumption, photolysis, and ventilation to the atmosphere. The time- and depth (0–60 m)-averaged gross DMS production was estimated to be 0.73±0.09 nM d−1 in the cyclonic eddy and 0.90±0.15 nM d−1 in the anticyclonic eddy, with respective DMS replacement times of 5±1 and 6±1 d. The higher estimated rate of gross production and lower measured loss rate constants in the anticyclonic eddy were equally responsible for this eddy's 50% higher DMS inventory (0–60 m). When normalized to chlorophyll and total dimethylsulfoniopropionate (DMSP), estimated gross production in the anticyclonic eddy was about twice that in the cyclonic eddy, consistent with the greater fraction of phytoplankton that were DMSP producers in the anticyclonic eddy. Higher rates of gross production were estimated below the mixed layer, contributing to the subsurface DMS maximum found in both eddies. In both eddies, gas exchange, microbial consumption, and photolysis were roughly equal DMS loss terms in the surface mixed layer (0.2–0.4 nM d−1). Vertical mixing was a substantial source of DMS to the surface mixed layer in both eddies (0.2–0.3 nM d−1) owing to the relatively high DMS concentrations below the mixed layer. Estimated net biological DMS production rates (gross production minus microbial consumption) in the mixed layer were substantially lower (by almost a factor of 3) than those estimated in a previous study of the Sargasso Sea, which may explain the relatively low mixed-layer DMS concentrations found here during July 2004 (3 nM) compared to previous summers (4–6 nM).  相似文献   

13.
Vertical profiles of dimethylsulfide (DMS) and β-dimethylsulfoniopropionate, particulate (pDMSP) and dissolved (dDMSP), were measured biweekly in the upper 140 m of the Sargasso Sea (32°10′N, 64°30′W) during 1992 and 1993. DMS and pDMSP showed strong, but different, seasonal patterns; no distinct intra-annual pattern was observed for dDMSP. During winter, concentrations of DMS were generally less than 1 nmol l−1 at all depths, dDMSP was less than 3 nmol l−1 and pDMSP was less than 8 nmol l−1. In spring, concentrations of both dDMSP and pDMSP rose, on a few occasions up to 20 nmol l−1 in the dissolved pool and up to 27 nmol l−1 in the particulate pool. These increases, due to blooms of DMSP-containing phytoplankton, resulted in only minor increases in DMS concentrations (up to 4 nmol l−1). Throughout the summer, the concentrations of DMS continued to increase, reaching a maximum in August of 12 nmol l−1 (at 30 m depth). There was no concomitant summer increase in dDMSP or pDMSP. The differences among the seasonal patterns of DMS, dDMSP, and pDMSP suggest that the physical and biological processes involved in the cycling of DMS change with the seasons. There is a correlation between the concentration of DMS and temperature in this data set, as required by some of the climate feedback models that have been suggested for DMS. A full understanding of the underlying processes controlling DMS is required to determine if the temperature-DMS pattern is of significance in the context of global climate change.  相似文献   

14.
In April 1997 and 1998 the significance of sedimentation as a sink for epipelagic dimethylsulphoniopropionate (DMSP) production and as a source for marine sediments was reassessed using a newly designed sediment trap. The behaviour of the traps in immersion was monitored continuously and the collection efficiency was evaluated with 234Th measurements. Net DMS(P) fluxes were corrected for some physical and biological losses during the whole sedimentation process providing reliable estimates of gross DMSP fluxes. It is shown that daily losses by sedimentation account for between 0.1% and 16% of seawater particulate DMSP (DMSPp) standing stocks, and between 3% and 75% of daily DMSPp production. In the Malangen fjord we observed temporal increases of DMSP production and standing stocks which resulted also in increases of DMSP vertical fluxes and DMS(P) concentrations at the sediment surface. This result illustrates how tight the coupling can be between pelagos and benthos, and confirms that DMS(P) concentration in the sediment was a reliable diagnostic indicator of vertical export from overlying waters in Malangen fjord. In Ullsfjord, however, DMS(P) concentrations in the sediment were poorly indicators of Phaeocystis pouchetii export during the early stage of growth of a bloom. The high load of DMS(P) in Balsfjord's sediments could neither be attributed to local vertical sedimentation nor to short-term lateral advection of fresh DMSP-containing phytoplanktonic material, and provides indication that this tracer sometimes also can be misleading. The highest loads of DMS(P) in sediments and the fastest rates of sedimentation occurred in the Southern Bight of the North Sea.  相似文献   

15.
《Marine Chemistry》2006,98(2-4):210-222
This study presents concentrations of dimethylsulphide (DMS) and its precursor compound dimethylsulphoniopropionate (DMSP) in a variety of sea ice and seawater habitats in the Antarctic Sea Ice Zone (ASIZ) during spring and summer. Sixty-two sea ice cores of pack and fast ice were collected from twenty-seven sites across an area of the eastern ASIZ (64°E to 110°E; and the Antarctic coastline north to 62°S). Concentrations of DMS in 81 sections of sea ice ranged from < 0.3 to 75 nM, with an average of 12 nM. DMSP in 60 whole sea ice cores ranged from 25 to 796 nM and showed a negative relationship with ice thickness (y = 125x− 0.8). Extremely high DMSP concentrations were found in 2 cores of rafted sea ice (2910 and 1110 nM). The relationship of DMSP with ice thickness (excluding rafted ice) suggests that the release of large amounts of DMSP during sea ice melting may occur in discrete areas defined by ice thickness distribution, and may produce ‘hot spots’ of elevated seawater DMS concentration of the order of 100 nM. During early summer across a 500 km transect through melting pack ice, elevated DMS concentrations (range 21–37 nM, mean 31 nM, n = 15) were found in surface seawater. This band of elevated DMS concentration appeared to have been associated with the release of sea ice DMS and DMSP rather than in situ production by an ice edge algal bloom, as chlorophyll a concentrations were relatively low (0.09–0.42 μg l− 1). During fast ice melting in the area of Davis station, Prydz Bay, sea ice DMSP was released mostly as extracellular DMSP, since intracellular DMSP was negligible in both hyposaline brine (5 ppt) and in a melt water lens (4–5 ppt), while extracellular DMSP concentrations were as high as 149 and 54 nM, respectively in these habitats. DMS in a melt water lens was relatively high at 11 nM. During the ice-free summer in the coastal Davis area, DMS concentrations in surface seawater were highest immediately following breakout of the fast ice cover in late December (range 5–14 nM), and then remained at relatively low concentrations through to late February (< 0.3–6 nM). These measurements support the view that the melting of Antarctic sea ice produces elevated seawater DMS due to release of sea ice DMS and DMSP.  相似文献   

16.
Data on the distribution of dimethylsulphide (DMS) and dimethylsulphoniopropionate (DMSP) in relation to phytoplankton abundance in different oceanic environments is important to understand the biogeochemistry of DMS, which plays an important role in the radiation balance of the earth. During the summer monsoon of 2001 measurements were made for DMS and DMSPt (total DMSP) together with related biological parameters in the Bay of Bengal. Both DMS and DMSPt were restricted to the upper 40 m of the water column. Diatoms accounted for more than 95% of the phytoplankton and were the major contributors to the DMS and DMSPt pool. The mean concentration of DMS in the upper 40 m was observed to be around 1.8+/-1.9 nM in the study area, while DMSPt concentrations varied between 0.7 nM and 40.2 nM with a mean of 10.4+/-8.2 nM. The observed lower DMSPt in the northern Bay in spite of higher mean primary productivity, chlorophyll a and phytoplankton cell counts seemed to result from grazing. Though salinity divides the Bay into different biogeochemical provinces there is no relation between salinity and DMS or DMSPt. On the other hand DMS was linearly related to chlorophyll a:phaeopigments ratio. The results suggest the need for deeper insight into the role of diatoms in the biogeochemical cycling of DMS.  相似文献   

17.
本研究首次探究了西太平洋雅浦海沟北段从表层到超深渊海水中甲烷（CH4）及二甲基硫（DMS）的前体物质二甲基巯基丙酸内盐（DMSP）的浓度变化情况。结果表明:雅浦海沟海水甲烷浓度变化范围为1.49~3.87 nmol/L。其上层海水甲烷平均浓度最高,有明显的次表层极大现象。雅浦海沟氧最小层海水的甲烷平均浓度最低;在500~1 000 m中层水中甲烷浓度有一定程度的增大,1 000 m以下至底层甲烷浓度继续升高。研究海区溶解态DMSP（DMSPd）和总DMSP（DMSPt）平均浓度的垂直变化随深度呈先增大后减小趋势,颗粒态DMSP（DMSPp）的平均浓度随深度呈波动式变化,在中层达到最大。雅浦海沟CH4和DMSP浓度垂直变化受浮游生物、微生物、光照、温度、压力、大洋环流等的复杂影响。在真光层海水中,CH4浓度与DMSPd、DMSPp和DMSPt浓度表现为负相关关系,在200 m至底层海水中,CH4浓度与DMSPd、DMSPp和DMSPt浓度表现为正相关关系,显示光照条件是造成雅浦海沟不同深度海水CH4和DMSP浓度相关性差异的关键因素。  相似文献   

18.
The effect of added iron on bacterial cycling of the climate-active gas dimethylsulfide (DMS) and its precursor dimethylsulfoniopropionate (DMSP) was tested during the second Subarctic Pacific Iron Experiment for Ecosystem Dynamics Study (SEEDS II) from 19 July to 21 August 2004 aboard the R/V Hakuho-Maru. The study area in the northwest Pacific Ocean (48°N 165°E) was enriched with Fe and the conservative tracer, SF6, allowing the fertilized patch to be tracked. Microbial DMSP cycling rates were determined in the surface mixed layer (5 m) during incubations using the 35S-DMSP technique. The addition of iron resulted in a 4-fold increase in concentrations of chlorophyll a (chl a) within the surface mixed layer (5 m depth), and the length of the sampling period allowed the observation of both bloom and post-bloom conditions. Inside the fertilized patch, the alleviation of resource limitation gave rise to the concurrent increase in bacterial abundance and production. Changes in the phytoplankton community within the Fe-enriched patch translated into a sustained decrease in chl a-normalized particulate DMSP (DMSPp) concentrations, suggesting a preferential stimulation of the growth of DMSPp-poor phytoplankton species. Despite short-lived peaks of DMSPp within the Fe-enriched area, concentrations of DMSPp generally remained stable during the entire sampling period inside and outside the fertilized patch. During the Fe-induced bloom, microbial DMSP-sulfur (DMSP-S) assimilation efficiency increased 2.6-fold inside the Fe-enriched area, which indicated that as bacterial production increased, a greater proportion of DMSP-S was assimilated and possibly diverted away from the bacterial cleavage pathway (i.e. production of DMS). Our results suggest that iron-induced stimulation of weak DMSPp-producers and DMSP-assimilating bacteria may diminish the potential production of DMS and thus limit its flux towards the atmosphere over the subarctic Pacific Ocean.  相似文献   

19.
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.  相似文献   

20.
The Arabian Sea is characterised by strong seasonal oscillations of biological productivity generated by its monsoonal climate. The southwest monsoon causes reversal in the surface circulation of the Arabian Sea, which generates a seasonal upwelling of nutrient-rich waters along the coast of Oman. Concentrations of biogenic sulphur compounds were measured on a transect from the eutrophic waters off the coast of Oman to the oligotrophic waters of the open Arabian Sea, during the UK NERC Arabesque cruise 27 August–4 October 1994. The concentrations of dimethylsulphide (DMS), dimethylsulphoxide (DMSO) and dimethylsulphoniopropionate (DMSP) were found to be elevated in the eutrophic area due to enhanced biological production. However, this increase in DMS, DMSO and DMSP concentration was not observed until after the southwest monsoon had relaxed, and appeared to correspond to increased concentrations of hexanoyloxyfucoxanthin, an indicator of prymnesiophytes. DMSO concentrations were correlated with those of DMS and DMSP in the near surface waters of the Arabian Sea. Additionally, DMSO appeared to be ubiquitous throughout the water column, being easily detectable in deep waters, which suggests that DMSO may act as a sink for DMS in the world’s oceans.  相似文献   

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