Chemical and GC-MS characterization of marine particulate lipids

The lipid fraction of particulate organic matter in seawater was analyzed by gravimetry, liquid chromatography, gas chromatography (GS), and gas chromatography—mass spectrometry (GS—MS). Gravimetric concentrations in the Gulf of Mexico were in the range of 12–70 μg 1^?1 for near-surface samples and 9–52 μg 1^?1 for near-bottom samples. The lipids accounted for ～20% of the particulate organic carbon. Particulate lipids were found to be a much more complex mixture of organic compounds than the dissolved lipids and their composition was much more variable. The majority of the extracted weight was recovered in the polar liquid chromatography fraction (49–85%). The major components of the analyzable particulate lipids were similar to those of the dissolved lipids, namely, n-alkanes, pristane, phytane, and methyl, ethyl and propyl fatty acid esters. Often olefins, alkylated benzenes, quinones, and the unresolved GC area contribute a substantial part to the total particulate lipids. Minor components included ketones, phenols, indanes, acids, benzoates, aromatics and possibly derivatives of inositol, dioxane, and pyran. The low concentrations observed confirm that the area is relatively pristine though some evidence for chronic low-level oil pollution was present. Seasonal, diurnal, vertical and areal variations were observed in the particulate lipids. Lipid concentrations not only decreased with depth but they were also a decreased percentage of the organic carbon present. This may indicate the loss of labile carbon with depth due to reworking in the euphotic zone. Anoxic conditions appeared to promote the preservation of lipid materials in the particulate phase, n-Alkanes and fatty acid esters were common to both the particulate and dissolved phases and had similar distributions.     

Advanced characterization of marine dissolved organic matter by combining reversed-phase liquid chromatography and FT-ICR-MS

Marine dissolved organic matter (DOM) was separated by reversed-phase (RP) liquid chromatography method and analyzed with fluorescence/absorption detection and Fourier transform ion cyclotron mass spectrometry (FT-ICR-MS). The three key characteristics of the RP method are: (a) The C18-RP column chosen provides enhanced separation when the aqueous phase is 100% buffer-free water, and it does not degrade over time; (b) the water eluent adjusted to pH 7 significantly improves the resolution of water soluble compounds; (c) the initial flow maintained at low levels improves the separation of polar compounds. In samples, containing “fresh” DOM, specific peaks were detected, which were absent in “old” DOM samples. The combination with size exclusion chromatography (SEC) also demonstrated the relation between polarity and molecular size of DOM. FT-ICR-MS was applied to evaluate the quality of separation on a molecular scale demonstrating that physico-chemical characteristics of DOM can be related to molecular formulas. Sample extracts were separated into 4 preparative fractions, and a large suite of the identified molecular formulas only occurred in specific fractions. This is an important basis for the application of further analytical techniques in order to perform a more target-oriented analysis aiming at the determination of source and process biomarkers for DOM.     

Chemical studies of dissolved carbohydrates in seawater

Charcoal column chromatography and a dialysis system using a Visking tube were used for the concentration and separation of dissolved carbohydrates in seawater. Recoveries of mono-, oligo-, and polysaccharides were 46–74, 61–89 and 70%, respectively, relative to the total amount of sugars initially submitted to analysis. The combined charcoal column chromatography and dialysis system was used to separate dissolved carbohydrates in seawater samples from Mikawa Bay into mono-, oligo- and polysaccharide fractions. The polysaccharides are separated into two fractions with molecular weights of <4,000 and >4,000 using Sephadex G-25 column chromatography. Monosaccharides, oligosaccharides, polysaccharides with M.W.<4,000 and polysaccharides with M.W. >4,000 accounted for 7–9, 15–26, 7–13 and 20–33% of total dissolved carbohydrates, respectively. However, 32–38% of dissolved carbohydrates were lost during the analytical procedures. Glucose, galactose, mannose, xylose, arabinose, ribose, fucose, and rhamnose were found upon acid hydrolysis of the oligo- and polysaccharide fractions, while fucose and rhamnose were not present in the monosaccharide fraction. Possible sources of the carbohydrates in these fractions are discussed with reference to the monosaccharide composition of cellular carbohydrate in marine algae.     

Release and uptake of dissolved silica in seawater by marine sediments

Natural marine sediments can release dissolved silica to silica-poor seawater and can remove silica from seawater enriched with dissolved silica. These are fast reactions, with sufficient reaction occurring within the first 48 hours to indicate clearly the direction of the reaction. The relative importance of these two processes varies with the ratio of clays to biogenic silica in the sediment. Both the release and the uptake reactions approach the interstitial water concentration of dissolved silica as an end point, which suggests that these reactions may influence this concentration. No change in sediment reactivity with respect to silica uptake or release reactions was observed with increasing depth in core for the three sediment cores investigated; this indicates that uptake sites are not saturated, and silica is available for dissolution for a long time after deposition.     

Vertical profiles of nitrous oxide and dissolved oxygen in marine sediments

The whole core squeezing method was used to simultaneously obtain profiles of nitrous oxide (N₂O), nitrogenous nutrients, and dissolved oxygen in sediments of Koaziro Bay, Japan (coastal water), the East China Sea (marginal sea), and the central Pacific Ocean (open ocean). In the spring of Koaziro Bay, subsurface peaks of interstitial N₂O (0.5–3.5 cm depth) were observed, at which concentrations were higher than in the overlying water. This was also true for nitrate (NO₃⁻) and nitrite (NO₂⁻) profiles, suggesting that the transport of oxic overlying water to the depth through faunal burrows induced in situ N₂O production depending on nitrification. In the summer of Koaziro Bay, sediment concentrations of N₂O, NO₃⁻ and NO₂⁻ were lower than in the overlying water. In most East China Sea sediments, both N₂O and NO₃⁻ decreased sharply in the top 0.5–2 cm oxic layer (oxygen: 15–130 μM), which may have indicated N₂O and NO₃⁻ consumption by denitrification at anoxic microsites. N₂O peaks at subsurface depth (0.5–6.5 cm) implied in situ production of N₂O and/or its supply from the overlying water through faunal burrows. However, the occurrence of the latter process was not confirmed by the profiles of other constituents. In the central Pacific Ocean, the accumulation of N₂O and NO₃⁻ in the sediments likely resulted from nitrification. Nitrous oxide fluxes from the sediments, calculated using its gradient at the sediment–water interface and the molecular diffusion coefficient, were −45 to 6.9 nmolN m⁻² h⁻¹ in Koaziro Bay in the spring, −29 to −21 nmolN m⁻² h⁻¹ in the summer, −46 to 37 nmolN m⁻² h⁻¹ in the East China Sea, 0.17 to 0.23 nmolN m⁻² h⁻¹ in the equatorial Pacific, and <±0.2 nmolN m⁻² h⁻¹ in the subtropical North Pacific, respectively.     

Laboratory and marine study of photoluminescent sensors of oxygen dissolved in seawater

The laboratory and marine study of photoluminescent sensors developed at the TsAGI has been conducted to create a highly sensitivity gauge of the oxygen dissolved in seawater. The advantages of the photoluminescent gauge over the electrochemical ones are the following: zero sensitivity to electromagnetic fields, the pH of the water, and the hydrogen sulphide and ions of heavy metals in the water; zero oxygen consumption; and no need for the water to be pumped through the device.     

Constraining the 2-component model of marine dissolved organic radiocarbon

Keeling plots of dissolved organic carbon (DOC) concentration and Δ¹⁴C depth profiles imply rapid, diapycnal transport of DOC to the meso- and bathypelagic zones, but do not constrain the mechanism of redistribution. We review the 2-component Keeling plot model, and present an alternative formulation explicitly based on homogenization of water parcels. Applying this new model to DOC and dissolved inorganic carbon (DIC) depth profiles suggests that the dominant controls on DOC redistribution differ throughout the water column. DOC concentration and Δ¹⁴C gradients were consistent with biogeochemical processing in the epipelagic and advection in the mesopelagic. Vertical gradients in DOC concentration and Δ¹⁴C were insufficient for further interpretation in the bathypelagic. Ultimately, additional concurrent measurements of DOC and DIC concentrations and Δ¹⁴C values throughout the water column at more locations are needed to constrain the applicability of two-component mixing models to marine DOC.     

海洋石油降解微生物的分离鉴定

以柴油为惟一碳源,从胜利油田黄河码头和厦门储油码头两个海水样品中富集得到两组柴油降解菌,共9株细菌,1株真菌,它们对柴油都有降解能力.16SrDNA鉴定结果表明这9株细菌中有3株摩加夫芽孢杆菌、1株施氏假单胞菌、1株腊样芽孢杆菌、1株反硝化产碱杆菌.1株阿氏葡萄球菌、1株食烷菌和1株类似很小海旋菌的未知新菌(M-5),其中B-5对柴油的降解能力最强,已报道的食烷菌属中其他种的同源性最高,为95.2%,表明它是该属中的一个新种.实验中获得的惟一一株真菌M-3属于假丝酵母,对柴油有较强的降解和乳化能力.实验中还从B5和施氏假单胞菌M-2中扩增到了烷烃降解的限速酶烷烃单加氧酶的基因片断,其中B5编码了一种新的烷烃单加氧酶.这些菌在石油污染的海水自净中起着重要作用,可用于海洋石油污染的生物修复.     

Complexation of copper and nickel in the dissolved phase of marine sediment slurries

Speciation of copper and nickel in the water phase of incubated marine slurries under aerobic conditions was performed with MnO₂ and Sep—Pak C₁₈ cartridges. Changes in time during the incubations of concentrations of dissolved organic carbon (DOC), dissolved copper and nickel and inorganic nitrogen were followed. The influence of organic complexation on the dissolved concentrations of copper and nickel was investigated as well as competition between copper and nickel for dissolved organic ligands.Two pools of dissolved organic ligands could be distinguished. With the MnO₂ method a relatively strong ligand group was determined that was subjected to degradation. The conditional stability constant for copper with the relatively strong ligand was 10^11.1. The conditional stability constant for the relatively strong nickel ligand was difficult to determine due to saturation of the ligand sites; it was found to be around 10¹⁰. However, it could not be ascertained whether nickel was reversibly com-plexed with the organic ligands.With Sep—Pak a relatively weak Hgand group was detected that was probably more resistant to degradation. The conditional stability constant of the weaker ligand could not be estimated, an approximation revealed that it was weaker than the ligand group determined with the MnO₂ method. For copper the difference between binding strength of the ligand groups was at least 100, for nickel the difference was less.Competition between copper and nickel for the ligands could not be detected. Only during the first day of the experiment, when the system was not in equilibrium was competition suspected. However, the replacement of nickel by copper from the ligand sites was not straightforward and could not be accounted for by our model.The concentration of total dissolved copper during the first week of the experiment was found to be controlled on the one hand by release from the sediment of copper already associated with dissolved organic matter (DOM) and on the other hand by concentration of the strongest ligand. The calculated free copper concentration increased from 10⁻¹² to 10⁻⁹mol l⁻¹ due to the oxidation of the strongest ligand. After saturation of the strongest ligand the relatively weak ligand controlled the free copper concentration. A continuing release of copper from the sediment by degradation of particulate organic matter (POM) will not increase the free copper concentration until the ligand sites of the weaker ligands get saturated.The total dissolved nickel concentration seemed only to be determined by the sum of the concentrations of the organic ligands. A degradation of ligands resulted in a decrease of the total dissolved nickel concentration. The calculated free nickel concentration did not change with time.     

溶解态磷在海洋微藻碱性磷酸酶活力变化中的调控作用

在实验室批量培养条件下,测定了海洋微藻培养体系中碱性磷酸酶活力(APA)和各形态溶解磷的动态变化,分析了二者之间的关系.结果表明,在批量培养过程中,APA的动态变化呈"S"形曲线,各形态溶解磷在其变化过程中所起的调控作用不同,介质中溶解无机磷和小分子溶解有机磷的浓度是激发APA发生变化的主要调控因子,大分子溶解有机磷的浓度对APA的作用不明显,但APA的增大可加速微藻利用大分子溶解有机磷的速率.微藻的种类和丰度不影响APA的动态变化形式及其调控机理.     

Effect of dissolved phosphorus on alkaline phosphatase activity in marine microalgae

I~IOXThe alkaline phOSPhataSe (AP) has been more and more studied following the study of thephosphorus limitation (Suttle and Harrision, 1988; Hu et al., 1989; Huang et al., 1996). PeOple used to take dissolved inorganic phOSphorus (DIP) level and uptake rate by algae as phosphOrus limitation indicators (Vera and Petterson 1992; Huang and HOng, 1994). But recent resultsindicate that diSSOlved organic phosphorus (DOP) and particulate organic phOSphorus (PP) couldalso be utilized b…     

Chemical processes and interactions involving marine organic matter

The concepts which have guided our thinking about chemical processes and interactions of organic matter in seawater are identified and their utility assessed. Some recommendations for the future are made.     

Role of eicosenoic and docosenoic fatty acids in fresh water and marine lipids

The isomeric compositions of the eicosenoic and docosenoic fatty acids of four freshwater fish oils (from sheepshead Aplodinotus grunniens, tullibee Coregonus artedii, maria Lota lota and alewife Alosa pseudoharengus, respectively) were examined by open-tubular gas—liquid chromatography. The 22:1ω11 isomer, usually the dominant isomer in marine-fish oils, was unimportant relative to 22:1ω9. The unsaponifiables lacked fatty alcohols and pristane and were mostly cholesterol. The probability that the 22:1ω1 in marine fish oils is strictly of an exogenous origin (primarily originating as the fatty alcohol in copepod wax esters) is reviewed and it is proposed that docosenoic acids have no obligatory role in the lipid biochemistry of either marine or freshwater fish.     

Isolation and characterization of low molecular weight carbohydrates dissolved in seawater

Chemical characterization and quantitative determination of dissolved low molecular weight carbohydrates in Mikawa Bay near Nagoya, Japan were conducted. The water samples were collected during the period of algal bloom of the dinoflagellate Prorocentrum minimum on 31 May 1980.Low molecular weight carbohydrates in seawater samples from depths of 1 and 6 m were first retained on a charcoal column and then eluted with aqueous ethanol. The carbohydrates obtained were permethylated and then isolated into each of the components by thin layer chromatography. The sugars isolated were characterized by gas chromatography (GC), combined gas chromatography and mass spectrometry (GC-MS), proton nuclear magnetic resonance spectroscopy (¹H-NMR) and some chemical analyses. Laminaribiose, laminaritriose, sucrose, raffinose,

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were fully characterized and quantified with ranges from 2.3 to 27.7 μg l⁻¹ and from 0.5 to 17.8 μg l⁻¹.These low molecular weight carbohydrates were also identified, with some difference in their relative abundance, in particulate matter consisting mainly of dinoflagellate cells collected on the same occasion from this bay. These results indicate that low molecular weight carbohydrates dissolved in seawater are directly derived from those of phytoplankton through extracellular release or cell lysis.     

Metaproteomic characterization of dissolved organic matter in coastal seawater

We performed a comprehensive metaproteomic analysis of the dissolved organic matter (DOM) in Japanese coastal waters using liquid chromatography–tandem mass spectrometry and demonstrated that these proteomes were characterized by proteins with various functions, including metabolic enzymes, membranes, and photosynthetic proteins. The protein sources included cyanobacteria, heterotrophic bacteria, and eukaryotic phytoplankton. Most of the components were similar among samples and also similar to pelagic components. We also observed differences in the compositions of the microbial communities of origin among the different dissolved protein samples and differences in the relative abundance of specific dissolved protein types (e.g., cytoskeletal proteins), possibly indicating potential dynamics in the coastal DOM pool.     

The inventory and chemical characterization of dissolved proteins in oceanic waters

One-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and high resolution two-dimensional electrophoresis (2-DE) were applied to separate protein molecules in dissolved organic matter (DOM) from oceanic waters. Results were: (1) The 2-DE distinguished a total of 412 protein spots in 10 samples from five water columns over the Pacific, although fewer than 30 proteins were resolved as bands from the identical samples by SDS-PAGE. (2) Major and ubiquitous protein bands (34 and 39 kDa proteins) on the SDS-PAGE gel were resolved into horizontally spread arrays (trains) of spots on the 2-DE gels, indicating that these bands were a mixture of protein species that have the same molecular weight (MW) but different isoelectric points (pIs). (3) Proteins that exhibited such electrophoretic patterns on the 2-DE gels were glycosylated with variable linkages between the sugar and polypeptide chains. (4) N-terminal amino-acid sequencing demonstrated that individual spots within each train of spots had identical N-terminal amino-acid sequences.The N-terminal amino-acid sequences of the 39 and 34 kDa glycoprotein spots in samples collected at different sites were also identical. Protein isoforms with the same amino-acid sequence but different glycosylation profiles, termed glycoforms, were often observed on the 2-DE gel. Thirty-one and 24 spots on the 2-DE gels were glycoforms of two glycoproteins with MWs of 39 and 34 kDa, respectively; they were one protein species. The glycoforms of the 39 kDa protein were identified as a low molecular weight alkaline phosphatase (L-AP) of Pseudomonas aeruginosa PAO1 by a homology search through five amino-acid sequence databases. The present and earlier work indicates that all identified source organisms of dissolved proteins belong to the Pseudomonas group. We propose the hypothesis that proteins associated with membrane vesicles liberated from a minor member of the bacterioplankton assemblage, the marine Pseudomonas group, are one of the important sources of dissolved proteins in oceanic waters. This hypothesis may apply to the source pathway and survival not only of proteins and also to the universally occurring bacterial peptidoglycan and lipopolysaccharide components in DOM.     

Identification of dissolved and particulate carbonyl compounds produced by marine harmful algal bloom species

Carbonyl compounds, especially polyunsaturated aldehydes (PUAs), are increasingly reported as teratogenic to grazers and deleterious to phytoplankton. While PUAs have been considered to be mainly produced by diatoms after cell wounding, little is known about whether microalgae other than diatoms, particularly harmful algal bloom (HAB)-forming species, produce carbonyl compounds. In this study, we analyzed the carbonyl compounds from eight common HAB-forming species ( Akashiwo sanguinea , Karenia mikimotoi , Karlodinium venefi cum , Margalefi dinium polykrikoides , Prorocentrum donghaiense , P . minimum , Scrippsiella trochoidea , and Heterosigma akashiwo ) using gas chromatography-mass spectrometry in full scan and selected ion monitoring (SIM) modes. Our results show a ubiquitous presence of carbonyl compounds in both dissolved and particulate forms in all species we examined. In the full scan mode, 133 chromatographic peaks were detected from 51 samples altogether. Both the varieties of carbonyl compounds and their quantities were algal species dependent, although most of the carbonyl compounds could not be fully identifi ed according to the mass spectral database only due to the unavailability of enough standards for all analytes. Aided with nine standards in SIM mode, we further identifi ed and quantifi ed all nine aldehydes (2-methyl-2-pentenal, trans-2-nonenal, cis-6-nonenal, 2,6-dimethyl-5-heptenal, trans-2-hexenal, trans-2- decenal, 2,4-heptadienal, trans-trans-2,4-octadienal, and trans-trans-2,4-decadienal). Four of these nine aldehydes were detected in particulate form, which confi rmed that trans-2-nonenal could be produced by K . mikimotoi , Karl . venefi cum , P . donghaiense , P . minimum , S . trochoidea , and H . akashiwo , 2,4-heptadienal and trans-trans-2,4-decadienal by A . sanguinea , M . polykrikoides , and S . trochoidea , and trans, trans-2,4- octadienal by S . trochoidea , respectively. We proved that some dinofl agellate and raphidophyte species could contribute to the pool of carbonyl compounds including PUAs in a marine ecosystem. Some carbonyl compounds, particularly those in high cell quota and/or dissolved concentration, may be related to fi shkilling or allelopathy which needs further identifi cation and quantifi cation.     

Application of an automated method for dissolved sulphate analysis to marine and brackish waters

A fully automated method for the analysis of dissolved sulphate was tested for saline and brackish waters. A small sample volume of ? 2 ml is required, making the method very suitable for analysis of interstitial waters. The method was calibrated for samples from natural waters in the Dutch delta region, containing up to 2500 mg l^?1 of sulphate, and with a salinity of 30‰.