南极夏季沿海P.Pouchetii繁殖期间丙烯酸和二甲基硫的自然产率

样品取自东南极距戴维斯站 1 0公里沿海海域 1 5米水层。从 1 988年 1 1月至 1 989年 2月 ,利用高压液相色谱和气相色谱等手段对海藻 Phaeocystis Pouchetii整个繁殖过程中所产生的有毒物质丙烯酸和二甲基硫的浓度进行了长期连续测定。结果表明 ,丙烯酸和二甲基硫的含量变化范围分别为 0 .0 0 1～ 0 .5 1 0 μmol/L和 0 .0 0 3～ 0 .5 88μmol/L。二者的含量变化与 P.Pouchetii细胞数量的变化完全一致 (相关系数均为 0 .998)。由此可见丙烯酸和二甲基硫产生于 P.Pouchetii是无疑的。丙烯酸和二甲基硫的最高产率分别是 9.75 8× 1 0 - 8μmol/cell和 1 3 .0 90× 1 0 - 8μmol/cell。其主要产生途径是 :P.Pouchetii摄取氨基酸 (如蛋氨酸 )后 ,经甲基化、脱胺等作用 ,在细胞分裂和代谢过程中产生二甲基硫丙酸 (DMSP) ,进而以一对一的方式分解成丙烯酸和二甲基硫。     

Dimethylsulfide oxidation and the ratio of methanesulfonate to non sea-salt sulfate in the marine aerosol

A box model of DMS oxidation in the clean, low-NO _x marine atmospheric boundary layer has been used to predict the latitude dependence of the aerosol methanesulfonate to non sea-salt sulfate ratio. The observed latitude dependence of this ratio in the Southern Hemisphere can be reproduced reasonably well if the full suite of reactions proposed by Yin et al. (1990a) is employed, and a strong temperature dependence is specified in the rates of decomposition of CH₃SO₂ and CH₃SO₃ radicals.     

东南极夏季中山站邻近固定冰DMS、DMSP分布初探

中国第30次南极科学考察期间,在中山站邻近固定冰区采集了两支海冰冰芯并首次分析其中的DMS、DMSP含量。结果表明,两支冰芯上层均含有较高浓度的DMSP+DMS,分别高达114.93及134.41 nmol·L-1。冰芯中DMS、DMSP+DMS浓度随深度的增加而递减。两支冰芯顶部DMSP+DMS高值的成因不同,冰芯1主要受藻类活动影响而产生DMSP+DMS高值,冰芯2主要是由于雪层及薄冰层阻碍,致使DMS在冰芯顶部聚集产生DMS高值。因为海冰底部较高生物量的海冰融化进入水体,所观测的剩余海冰底部Chl a、DMSP+DMS值均较低。在海冰的融化过程中,卤道内的卤水可发生垂向运输,致使冰芯中Chl a、DMSP+DMS的垂直分布有所不同。冰芯的Chl a、DMSP+DMS总量分别为6.79和10.20、51.83和88.41μmol·m-2,与前人研究结果比较,在海冰融化过程中,海冰中Chl a、DMSP+DMS总量变化的总趋势是递减的。     

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.     

互花米草入侵对海岸盐沼二甲基硫及氧化亚氮气体释放的影响

为探讨互花米草(Spartina alterniflora)入侵对我国沿海生态系统的影响,采用静态采样箱法,研究了互花米草入侵滩涂和临近未入侵滩涂在二甲基硫(DMS)、氧化亚氮(N2O)气体通量上的差异及其相关因素.结果显示,互花米草滩DMS和N2O释放量均显著高于临近光滩、盐蒿滩和芦苇滩.该两种气体释放量同植被地下生物量、总生物量以及土壤有效氮含量均呈显著正相关,DMS气体通量还与植被地上生物量有关,但两种气体通量与土壤有机质含量均无直接相关性.研究说明互花米草生物入侵不仅改变了生态系统结构,还能通过改变区域温室气体排放通量进而影响到全球气候变化.     

海洋中二甲基亚砜的来源、分布及迁移转化

二甲基亚砜(DMSO)是海水中的主要溶解态甲基硫化物,DMSO在二甲基硫(DMS)的生物地球化学循环中起着重要的作用。它能通过DMS的光化学氧化和细菌氧化生成,可作为DMS的1个汇,也可以通过生物直接合成或其它途径产生。DMSO同时又可以被酶、细菌、植物等还原为DMS,因此,DMSO又可充当DMS的1个源。DMSO除了能被还原为DMS外,还可能会被细菌氧化为SO42-,在氯过氧化物酶作用下被H2O2氧化为DMSO2等。海洋中DMSO的测定通常采用还原剂NaBH4将其还原为DMS后,再利用气相色谱进行测定。海水中DMSO的分布不均匀,高浓度区是那些温度较高,光照充足、浮游植物较多、生物活性较高的表层水或近岸水。     

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.     

环境因子对浒苔生长及生源硫释放的影响

近年来,我国黄海海域大规模暴发的绿潮现象对海洋生态环境和海水中的物质迁移转化产生了重要影响。而浒苔作为绿潮暴发过程中的主要藻类,是释放二甲基硫(DMS)的优势藻类,其对海水中硫酸盐吸收转化及生源硫释放发挥着重要作用。本文通过实验室培养探讨了温度、盐度及不同形态氮营养盐对浒苔生长及释放生源硫化物的影响。结果表明,在实验范围内(盐度为25—35,温度为20—25°C),盐度对浒苔生长无明显影响,但盐度增加会促进β-二甲基巯基丙酸内酯(DMSP)的合成。在温度为20°C盐度为35时,DMSP释放达到最大值。温度增加能够促进浒苔的增长,在培养第5天,25°C下浒苔湿重比20°C增加了25%左右。培养液中的DMS含量为20nmol/L左右,约是正常黄海水的4倍,DMSP的浓度更是高于正常海水的数十倍。增加无机氮浓度会促进浒苔的生长及DMS和DMSP的释放,相比之下,NH4+-N比NO3–-N更易被浒苔吸收利用,添加两种氮源组DMS和DMSP的最高含量均比空白组高60%和30%左右。DMS/DMSP的值在10%以内变化,培养过程中DMSP表观降解比AA(丙烯酸)/(AA+DMSP)总体上低于40%。     

海洋浮游生态系统中D MS P的来源及在食物链中的传递和转化研究进展

β-二甲基巯基丙酸内盐(DMSP)是一种在海洋中普遍存在的重要生源有机硫化物,其降解产物二甲基硫(DMS)挥发到大气中会形成云凝结核,进而对大气温度产生负反馈效应.DMSP主要由浮游植物和部分细菌生物合成,在浮游食物链和微食物环中进行传递和转化,并进一步通过食物网进入更高营养级.浮游生物是驱动全球碳、硫循环的关键环节,...