酸化过程对海洋沉积物中有机碳同位素分析的影响

海洋沉积物中有机碳同位素(δ13C)可以示踪海洋生态系统中有机质来源,对环境研究具有重要意义。分析沉积物中有机物的δ13C,需要对样品进行酸化,以去除无机碳的影响。由于不同来源的沉积物中无机碳的含量和组份存在差异,需要针对样品性质,优化酸化处理过程。本研究分别选取了无机碳含量不同的温带与热带河口、海湾沉积物样品,比较了3种不同酸化过程对有机物δ13C分析的影响。研究结果表明:方法1(酸洗法)中6%H_2SO_3和1mol/L H_3PO_4对无机碳含量较高的热带河口、海湾样品去除效率较低,而2mol/L HCl去除无机碳酸盐的效果较理想。方法2(酸蒸法)并不适用于无机碳含量较高的热带河口、海湾样品;而对于无机碳含量相对较低的温带河口、海湾样品,9h酸蒸较为适宜。方法3(非原位酸洗)的结果较方法1和方法2偏正,表明其对含13C丰富的有机组分破坏较小,且方法3中残留的酸对δ13C的分析没有影响。因此,方法3是去除海洋沉积物中无机碳较理想的方法。     

The relationship between fatty acid distributions and bacterial respiratory types in contemporary marine sediments

Bacterial communities of different respiratory types were isolated from a marine sediment in a multiple chemostat system in an attempt to obtain bacterial cultures representative of the sediment. The fatty acid distribution of a mixed culture of sulphate-reducing bacteria isolated from this system showed a good correlation with the lipid distribution of the zone of maximum sulphate-reduction activity within the sediment. Both distributions had significant concentrations of C14 : 0, iso and anteiso C15 : 0, C16 : 0, C16 : 1ω7 and C18 : 1ω7. This was in contrast to the lipid profile of Desulfovibrio desulfuricans obtained by batch enrichment, which was dominated by iso C17 : 1ω7 fatty acids and correlated poorly with the sediment. The bacterial community cultured from the sediment was further differentiated according to respiratory types (aerobic, facultative aerobic and facultative anaerobic) by growth in a chemostat under defined conditions. The fatty acid distributions of these communities were sufficiently different to enable the various respiratory types to be recognized by their particular fatty acid composition. Cyclopropyl fatty acids (?17 and ?19) were present in significant levels only in the aerobic bacteria, while the facultative aerobes had significantly higher C18 : 1ω7 than the other cultures and the facultative anaerobic community was the only culture to have significant amounts of C12 : 0. The fatty acid distribution of Loch Eil sediment over the range C12-19 seemed to be predominantly of bacterial origin and were relatively abundant to a depth of 6 cm. The concentration of cyclopropyl fatty acids was highest in the oxidized surface sediments and decreased with depth as anaerobic conditions began to dominate, indicating that these fatty acids may only be indicative of aerobic sedimentary bacteria. In contrast to the fatty acids characteristic of bacteria, those fatty acids in the range C20-30 attributed to a terrestrial input were found in relatively constant concentrations over the whole 0–12 cm depth profile.     

Acetate in recent anoxic sediments: Direct and indirect measurements of concentration and turnover rates

While acetate is generally regarded as an important intermediate in the mineralization of organic matter in anoxic sediment systems, some quantitative studies in marine systems (including our own) have measured acetate oxidation rates in excess of sulphate reduction rates where sulphate is known to be the principal electron acceptor. We revisited Skan Bay, Alaska, where we had previously made such observations, for a reexamination of acetate turnover. Measurements of acetate concentrations, production rate, oxidation rate and sulphate reduction rate as well as bioenergetic considerations led to the conclusion that acetate oxidation rate in 15–18-cm deep sediment is 1·1–1·5 μM h⁻¹. The possibility that previous measurements were high because of a non-citric-acid-cycle pathway of acetate oxidation (suggested by recent laboratory studies) was excluded. It appears that our previous turnover measurements were high mainly because of high acetate concentrations. Procedures used for the isolation of porewater for acetate determination may influence results to an extent not previously recognized.     

微波散射实验识别原油及乳化原油

海上原油泄漏在其风化迁移过程中会形成不同浓度的乳化物,严重威胁海洋生态环境。合成孔径雷达(SAR)因其不受雨、云影响,可昼夜监测的优势,在海上溢油监测过程中发挥着主力军的作用,但是它在原油乳化识别方面还存在着不足。本文利用C波段全极化散射计观测原油的自然乳化过程,并利用人工制备的不同含水率的乳化油品模拟原油乳化进程观测油膜后向散射系数(N_(RCS))的变化。实验结果表明乳化原油M_(RCS)高于未乳化原油,且油膜乳化程度越高相应的N_(RCS)越大。通过油水散射差值(Δσ~0)与阻尼比(D_R)发现能够识别乳化与未乳化原油,反映油膜乳化程度的变化,且在VV极化下效果最佳。     

Structure and chemistry of sediments in Belfast Lough,a semi-enclosed marine bay

In a study of the benthic environment of Belfast Lough the structure of the subtidal sediment was examined along with its content of organic matter and selected metals (Cr, Mn, Ni, Cu, Zn, Pb). A wide range of sediment types occurred within the lough but the mean grain sizes for individual sites lay predominantly within the size classes of fine sand, very fine sand and silt. The content of organic matter and metals in the sediments showed strong positive correlations with each other and with the content of silt/clay. Both organic matter and metals decreased in concentration in a seawards direction. The content of organic matter lay generally within the range of 1–5% which is normally associated with shelf sediments, but constituted up to 12% of the sediment in the docks area. Likewise, metals were usually within the range reported within other nearshore coastal waters of the U.K., but sediments in the docks area and inner lough were enriched with several metals. Cluster analysis identified four major subdivisions in the lough which were distinctly different in their contents of silt/clay, organic matter and metals.     

元素分析仪快速测定海洋沉积物TOC和TN的条件优化

报道了在优化样品前处理、燃烧温度、最小加氧量和最佳称样量的基础上,综合构建优化了直接固体进样varioMACRO cube元素分析仪同时测定海洋沉积物样品中总有机碳(TOC)和总氮(TN)的条件,即准确称取20~30 mg沉积物样品用1 mol/L盐酸除去无机碳后,直接进样在燃烧管温度960℃,次级燃烧管温度830℃,还原管温度900℃,氦气压力0.12 MPa,流量600 mL/min,氧气压力0.20 MPa,加氧量22.5 mL仪器条件下,用标准曲线法峰面积获取TOC和TN浓度。结果表明,海洋沉积物中TOC和TN测定的检出限分别为0.0508%和0.0146%,回收率分别为97.7%~100.9%和97.2%~101.1%,对4个实际外海沉积物样测定总有机碳和总氮结果的相对标准偏差(RSD)为0.83%~3.06%和1.33%~3.49%(n=12)。该方法操作简便快速、灵敏度高,具有较好的精密度和准确度,可准确可靠地用于海洋沉积物中总有机碳和总氮含量的测定。     

辽河兴隆台构造带原油类型及分布特征

对原油地球化学特征进行对比分析,将辽河西部凹陷兴隆台构造带原油划分成4种类型。各类原油的正构烷烃碳数分布曲线、甾萜类成熟度参数、Pr/Ph等指标有较大差异,并在该区呈规律分布。总体表现为第三系原油由南至北成熟度参数和Pr/Ph值呈降低的趋势,正构烷烃碳数从单峰变化为双峰分布;太古宇潜山内幕及潜山表层原油性质相似,其成熟度明显高于第三系原油。原油分布主要受控于南北洼陷生油层成烃演化差异及与断裂发育时期的相互配置关系。     

原油WSF对三种海洋鱼类肝微粒体EROD活性的诱导和恢复的比较

研究了实验室条件下原油水溶性组分(WSF)暴露对黑鲷、黄鳍鲷和褐菖鲉肝微粒体EROD活性的剂量-效应,时间-效应和恢复过程。实验结果表明,在剂量诱导实验中,褐菖鲉肝EROD活性在原油WSF浓度为50μg/dm3时呈现生物统计学上的显著差异,而黑鲷和黄鳍鲷肝EROD活性在75μg/dm3时才呈现生物统计学上的显著差异;褐菖鲉肝EROD活性诱导倍数最高,但黑鲷的诱导浓度范围较广。在时间诱导实验中,在40μg/dm3原油WSF暴露下黄鳍鲷肝EROD活性在2 d时首先呈现显著差异;三种鱼肝EROD活性均在第4天达到最高,并呈现显著性变化,此后随着暴露时间的延长而逐渐下降并接近对照组水平。在恢复实验中三种鱼肝EROD活性下降并恢复到对照组水平。研究结果表明:对于石油污染物,黑鲷、黄鳍鲷和褐菖鲉肝EROD活性都可以作为污染生化效应监测指标,然而就三种鱼类比较而言,褐菖鲉最敏感,更适合于作为石油类污染及其生化效应,尤其是低剂量效应的监测生物。     

原油WSF对三种海洋鱼类肝微粒体EROD活性的诱导和恢复的比较

研究了实验室条件下原油水溶性组分(WSF)暴露对黑鲷、黄鳍鲷和褐菖鲉肝微粒体EROD活性的剂量-效应,时间-效应和恢复过程。实验结果表明,在剂量诱导实验中,褐菖鲉肝EROD活性在原油WSF浓度为50 μg/dm³时呈现生物统计学上的显著差异,而黑鲷和黄鳍鲷肝EROD活性在75 μg/dm³时才呈现生物统计学上的显著差异;褐菖鲉肝EROD活性诱导倍数最高,但黑鲷的诱导浓度范围较广。在时间诱导实验中, 在40 μg/dm³原油WSF暴露下黄鳍鲷肝EROD活性在2 d时首先呈现显著差异; 三种鱼肝EROD活性均在第4天达到最高,并呈现显著性变化,此后随着暴露时间的延长而逐渐下降并接近对照组水平。在恢复实验中三种鱼肝EROD活性下降并恢复到对照组水平。研究结果表明:对于石油污染物,黑鲷、黄鳍鲷和褐菖鲉肝EROD活性都可以作为污染生化效应监测指标,然而就三种鱼类比较而言,褐菖鲉最敏感,更适合于作为石油类污染及其生化效应,尤其是低剂量效应的监测生物。     

活性铁对海洋沉积物中有机碳的保存作用

沉积物碳汇是海洋碳汇的重要组成部分,揭示沉积物的储碳机制对研究气候变化与全球碳循环的相互作用具有重要意义。矿物对有机碳的保护作用是有机碳最重要的稳定机制,其中活性铁（FeR）在沉积物有机碳的累积作用中发挥着捕获有机碳并形成“铁锈碳汇”的重要作用。本文系统梳理了近年来关于海洋沉积物中FeR的固碳的研究成果,总结了海洋沉积物中FeR的提取方式、类型、固碳量、固碳机制、结合有机质来源及分子类型,阐述了FeR固碳的重要意义,旨在加深对矿物与有机碳相互作用的理解。海洋沉积物中FeR常通过柠檬酸盐 碳酸氢盐 连二亚硫酸盐(CBD)还原提取,主要以针铁矿、水铁矿及赤铁矿等氧化物形式存在。FeR可以结合沉积物中约80%的有机碳,结合机制包括以配体交换为主的吸附机制和共沉淀/螯合机制。FeR与有机碳的结合机制可依据铁结合有机碳（FeR OC）与FeR的摩尔比值（FeR OC∶FeR）简单判定,当FeR OC∶FeR低于1.00时以吸附方式结合,大于1.00时以共沉淀方式结合,且共沉淀相比吸附机制具有更高的有机碳结合量及稳定性。大部分海洋沉积物中FeR优先与海源类有机质结合,但在氧化还原频繁的河口及三角洲地区倾向与陆源类有机质结合。分子模拟实验、木质素氧化降解及近边X射线吸收精细结构光谱表明FeR与芳香碳及羧基碳等有机质具有更高的亲和性。FeR对有机质的稳定保存及减缓气候变化引起的负反馈具有重要意义,建议未来更多关注沉积物中有机质与铁矿物结合的具体过程及不同沉积环境FeR固碳的差异机制,更加关注不同结合机制的定量化及重要性对比研究。     

酸洗法测定海洋沉积物有机碳和无机碳含量的致命缺陷

Organic and inorganic carbon contents of marine sediments are important to reconstruct marine productivity,global carbon cycle, and climate change. A proper method to separate and determine organic and inorganic carbons is thus of great necessity. Although the best method is still disputable, the acid leaching method is widely used in many laboratories because of its ease-of-use and high accuracy. The results of the elemental analysis of sediment trap samples reveal that organic and inorganic carbon contents cannot be obtained using the acid leaching method, causing an infinitely amplified error when the carbon content of the decarbonated sample is 12%±1% according to a mathematical derivation. Acid fumigation and gasometric methods are used for comparison, which indicates that other methods can avoid this problem in organic carbon analysis. For the first time, this study uncovers the pitfalls of the acid leaching method, which limits the implication in practical laboratory measurement, and recommends alternative solutions of organic/inorganic carbon determination in marine sediments.     

海洋沉积物中金属依赖型甲烷厌氧氧化作用研究进展及展望

海洋沉积物中大部分甲烷会通过甲烷厌氧氧化作用（anaerobic oxidation of methane, AOM）而被消耗。早期研究表明,AOM可与硫酸盐、硝酸盐和亚硝酸盐的还原作用相耦合,从而有效减少甲烷向大气的排放。最近,金属依赖型AOM（metal-AOM,活性金属氧化物还原反应驱动的AOM）被证实存在于自然界沉积物和富集培养的样品中。但是,目前仍未从自然海洋环境中分离获得能够介导metal-AOM的微生物。对海洋沉积物中metal-AOM的研究大多聚焦于热液或冷泉等海洋特殊生境,一系列研究表明地质流体在这些海底化能自养生态系统的维持和演化方面起到了重要作用,并深刻影响全球地球化学循环,因此,该科学问题研究吸引了越来越多的注意力。本文讨论了可能参与海洋沉积物中metal-AOM的微生物类群及其地球化学证据,并在前人工作基础上,以冲绳海槽冷泉-热液共生区为例,提出一种新的metal-AOM作用机制。认为在全球冷泉-热液系统相互作用地区的调查有助于更好地探讨metal-AOM的发生机制及微生物在深海生境中分布的连通性问题。     

原油水溶性成分对斜带髭鲷受精卵及仔鱼的急性毒性效应

以2008年8月的北部湾涠洲岛附近发生特大溢油事故为背景,研究涠洲岛原油水溶性成分对斜带髭鲷（Hapalogenys nitens）受精卵孵化及仔鱼的急性毒性效应.受精卵24 h孵化试验中,原油水溶性成分对斜带髭鲷受精卵孵化抑制的半效应浓度EC50（95%置信限）为2.02（1.25～3.25）mg/dm^3,且抑制效应随着浓度的升高而增强;同时,原油水溶性成分对刚孵出的仔鱼具有明显的致畸或致死效应.仔鱼的48 h急性毒性试验中,仔鱼12、24和48 h的半致死浓度LC50（95%置信限）分别为0.91（0.65～1.29）、0.16（0.06～0.50）、0.14（0.05～0.43）mg/dm^3.可见原油水溶性成分对斜带髭鲷受精卵孵化及刚孵出幼体具有明显的急性毒性效应.     

O/W型TR-02稠油乳状液的配制及静态稳定性评价

针对河南油田L131井稠油,采用自制的TR-02乳化剂,根据稠油乳化降黏原理及O/W型乳状液的形成机制,研究了乳化剂的类型和含量、乳化方式、搅拌方式和搅拌速度、相体积分数等对O/W型稠油乳状液稳定性的影响,特别是初步探讨了在TR-02中加入纳米助剂TR-23,对O/W型稠油乳状液稳定性的影响,为纳米材料在稠油乳化降黏中的应用提供一个可参考的基础数据。     

综合风化条件下渤海原油中PAHs 变化特征研究

以渤海某原油作为研究对象进行50 d综合模拟风化实验,探讨了原油中五类PAHs组分的分布情况及其风化规律.结果表明:经过50 d风化,原油中PAHs的分布发生了较大的改变:萘系列化合物损失最为严重,相对浓度的损失达到56.78%;菲系列所占的比例有所提高,二苯并噻吩、屈、芴系列则保持相对稳定,其分布特征变化规律为进一步筛选溢油来源鉴别新诊断比值参数提供了一定的导向性;经风化检验,现有常用6种PAHs诊断比值在风化50 d后稳定性良好,可用于风化溢油的鉴别.     

Microbial nitrogen transformations in sediments and inorganic nitrogen fluxes across the sediment/water interface on the South Island West Coast,New Zealand

In January 1982, sediment microbial N transformations and inorganic N fluxes across the sediment/water interface were studied at nine sites off the South Island West Coast, New Zealand. The sediments showed a great variety in physical, chemical and biological properties. The sediment organic matter had a molar $\text{C}\text{N}$ ratio of 5.9–10.9, and the total $\text{N}\text{P}$ ratio was 1.2–4.0. The denitrification capacity in the top 7.5 cm of sediment was 0.1–77.2 mmol N m^?2 day^?1 and generally declined with increasing sediment depth. The in situ denitrification rate was 0.02–1.84 mmol N m^?2 day^?1 and highest activities were generally found in surface sediments and at 6–7.5 cm depth. Denitrification accounted for 82–100% of total nitrate reduction. Net N mineralization was indirectly estimated at 0.6–2.4 mmol N m^?2 day^?1, and the experimental determination of this N transformation gave 0.6–3.2 mmol N m^?2 day^?1. Denitrification accounted for 3–75% of net N mineralization. The diffusive flux of ammonium and nitrate across the sediment/water interface was 0.1–0.7 and 0.1–0.6 mmol N m^?2 day^?1, respectively.     

渤海南部海域柱状沉积物中氮的形态与有机碳的分解

海洋沉积物中氮形态的研究是研究其生物地球化学循环的重要前提,柱状沉积物中氮的形态分布在一定程度上反映了其早期成岩作用的进程及结果.利用分级浸取分离方法首次对渤海南部海域自然粒度下5个柱状沉积物样品进行了分析,依据是否可由试剂提取将其分为可转化态和非转化态,系统地研究了可转化态中各形态氮的分布特征及早期成岩作用.研究表明,渤海南部海域自然粒度下柱状沉积物中,OSF-N和IEF-N是可转化态氮的优势形态.各形态氮的含量随深度变化趋势不同,成岩作用亦不同.沉积物中有机氮的分解速率常数为15.51×10-3a,且对各生源要素的分解速率常数有N>P>C>Si;OC/TN比值远小于OC/ON,说明沉积物中保留了大量无机氮(IN)和非转化的有机氮,OC/ON值随深度增加而减小是由于沉积物中富集了ON;柱状沉积物中,表层比深层可转化态氮占其总量的比例高,在局部区域由于深层沉积物中氮的“再活化”导致二者几乎相同.     

华南沿海若干砂质海滩沉积物粒度特征的分析

根据2003年7月在华南沿海12个砂质海滩所取得的76个沉积物样品（其中次表层样品36个,不计入研究范围）,就该区的沉积物粒度特征展开论述。为了便于分析其沉积物粒度特征,我们把华南沿海12条海滩剖面根据岸滩形态和成因将华南砂质海岸划分为岬湾型砂质海岸、沙坝-渴湖型砂质海岸和夷直型砂质海岸三大类。阐述了不同类型海滩的表层沉积物的粒度特征、类型、分布以及粒度的沿程变化特征。     

Nitrogen forms and decomposition of organic carbon in the southern Bohai Sea core sediments

Study on form characteristics of nitrogen in marine sediments is the primary method to research its biogeochemical cycling and nitrogen form characteristics in core sediments can reflect the process and results of early diagenesis in a certain degree. In this paper, Sequential extraction process in natural grain size was used for studying the existent forms of nitrogen in five core sediments of the southern Bohai Sea for the first time. Nitrogen was divided into two parts -transferable and fixed based on whether it could be extracted by the reagent. Distributions and early diagenesis of transferable nitrogen forms in the southern Bohai Sea were researched integratedly. Results indicate that IEF - N and OSF-N are predominant forms in transferable part in the studied core sediments. Contents of different nitrogen forms vary differently with depth, and have different diagenesis process. Decomposition constant of organic nitrogen (ON) and OC are about 15.51 × 10~(-3)a~(-1)and 4.79× 10~(-3)a~(-1) respective