Carbon dioxide and carbon monoxide photoproduction quantum yields in the Delaware Estuary

Photochemical mineralization of dissolved organic matter (DOM) plays an important role in the cycling of carbon in estuarine systems. A key to modeling this process is knowledge of apparent quantum yields (AQYs) for the photochemical products. Here we determined spectral AQYs for carbon dioxide (CO₂) and carbon monoxide (CO), the main products of DOM photomineralization, along the main axis of the Delaware Estuary. Apparent quantum yields for CO₂ photoproduction were determined shipboard using a multi-spectral irradiation system. Carbon monoxide AQYs were determined in stored samples by employing a narrow band spectral irradiation system. A single AQY spectrum described carbon dioxide photochemical production within the estuary whereas CO AQY spectra varied with salinity, suggesting different precursors and mechanisms for the production of these two species. CO₂ AQYs were used along with shipboard measurements of DOM absorbance and solar irradiance to calculate photoproduction rates. Calculated CO₂ photoproduction rates agreed with directly measured rates (2 to 4 μM CO₂ d^? 1) within experimental error, supporting the further development and use of AQYs to calculate regional-scale photochemical fluxes.     

Simultaneous determination of dissolved organic carbon and total dissolved nitrogen in seawater by high temperature catalytic oxidation: conditions for precise shipboard measurements

Appropriate conditions have been achieved for the accurate, rapid, and highly precise shipboard simultaneous determination of dissolved organic carbon and total dissolved nitrogen in seawater by high temperature catalytic oxidation. A nitrogen-specific Antek 705D chemiluminescence detector and a CO₂-specific LiCor Li6252 IRGA have been coupled in-series with a Shimadzu TOC-5000 organic carbon analyser. Precision of both simultaneous measurements is ≤1.5%, i.e. ±1 μmol C l⁻¹ and ±0.3 μmol N l⁻¹, respectively. Quality of analysis is not compromised by vibrations associated with ocean going research vessels.     

Wet-oxidation and automated colorimetry for simultaneous determination of organic carbon, nitrogen and phosphorus dissolved in seawater

We developed a simple and reliable method which allows simultaneous determination of organic forms of carbon (DOC), nitrogen (DON) and phosphorus (DOP) dissolved in seawater. Conversion of dissolved organic matter (DOM) to inorganic products (carbon dioxide, nitrate+nitrite and soluble reactive phosphate) is performed by a persulfate wet-oxidation in low alkaline condition. After oxidation, the concentration of the inorganic products dissolved in the sample was measured automatically by colorimetry using a 3-channel Technicon AutoAnalyzer system. A number of pure organic compounds were tested in the concentration range encountered in coastal and open ocean, indicating a high efficiency of the digestion procedure. The recovery range is similar to that obtained by other wet-oxidation procedures and by high-temperature catalytic oxidation techniques. Direct comparisons with usual methods used for separate determination of DOC, DON and DOP indicated a high efficiency of the procedure. Reproducibility tests demonstrated a very good precision (around 5%) for lagoonal and coastal waters, while precision was sometimes around 10–25% in oligotrophic oceanic waters, especially for DOP where values approached limits of detection for measuring phosphate. This method is highly suitable for routine analysis and especially appropriate for shipboard work.     

濮城油田沙一段油藏濮1—1井组二氧化碳驱研究及先导试验效果分析

根据沙一油藏的物性特点,开展了CO2驱研究,室内进行了地层原油相态、压力组分、注CO2压力等实验。为了确定合理的开采方式,进行了连续注CO2、水气交替注入等实验研究。室内实验表明,在沙一油藏进行CO2驱是可行的。在室内模拟和CO2驱替实验的基础上,在现场开展了矿场试验。通过在濮1—1井进行试验,井组取得了好的效果,日增油8．5t,累积增油1150t。这为下步濮城油田高含水油藏进一步提高采收率提供了新的途径。     

An automated photochemical method for the determination of dissolved organic carbon in sea and estuarine waters

An improved version of Ehrhardt's (1969) method for the analysis of dissolved organic carbon is described. The method, which is automated, determines the carbon dioxide with a non-dispersive infra-red analyser. The conditions of photo-oxidation have been examined in order to achieve maximum performance. It was found that careful attention needed to be paid to U-V source, “oxygen source”, pH and time or irradiation. The completeness of the method was examined by three independent procedures. We concluded that in all cases the extent of oxidation of organic material was in excess of 98%. Typical performance figures were: precision ±2.5% above 2.0 mg C l^?1, approaching 0.03 mg C l^?1 below 1.0 mg Cl^?1; blank, equivalent to 0.3 mg C l^?1; sampling frequency, 10 samples per hour. The lower limit of sensitivity is mainly governed by the blank. The upper limit of the method is greater than 40 mg C l^?1.A wholly continuous modification of the method has been devised which permits on line analyses. An attentuated version of the method has been used for the analysis of total carbonate.The present and other published methods for the analysis of dissolved organic carbon in natural waters are discussed in relation to one another.     

走航ADCP观测资料质量控制方法及应用

为完善目前走航ADCP观测资料质量控制尚未形成统一流程的问题,将走航ADCP观测资料质量控制归纳为船速获取、声速校正、偏角校正以及剖面数据处理四个主要步骤,并制定了一套较为系统的走航ADCP观测资料质量控制流程。以渤海辽东湾红沿河核电站周边海域船载走航ADCP观测为例,按照提出的流程进行走航ADCP观测资料的质量控制。通过对比原始观测数据,质量控制后的结果表明u分量流速剔除了23.56%的低可信度数据,而v分量流速剔除了25.96%的低可信度数据。10 m与15 m水深处的质量控制前后的流速-频数直方图表明,本文提出的流程能有效地降低观测随机性的影响。     

Hydrocarbons in an urban atmosphere

Statistical characteristics of variations in surface-layer concentrations of methane, non-methane and aromatic hydrocarbons, carbon dioxide, and formaldehyde are compared with the characteristics of variations in the concentration of carbon monoxide in the air basin of Moscow. Differences in the annual cycle of concentrations of methane, carbon dioxide, non-methane hydrocarbons, and carbon monoxide are determined. It is found that the maximum concentration of carbon monoxide at most sites with an elevated surface-air pollution level and over the city as a whole tends to occur in the summer season. The seasonal variability of the diurnal mean cycle of methane, carbon dioxide, and non-methane and aromatic hydrocarbons is analyzed.     

Carbonate removal by acidification causes loss of nitrogenous compounds in continental margin sediments

This study reports on measurements of organic carbon (C_org) and total nitrogen (N_tot) in surface sediments originating from 6 transects along the northwest European continental margin. After elimination of carbonates by an acidification technique using sulphurous acid, both elements were analysed in the same sediment sample using an elemental analyser. C_org and N_tot in the sample were comparatively low, ranging between 1 and 10 mg C and 0.2 to 1 mg N g⁻¹ dry sediment. In a second analysis, the samples were analysed without acid addition, resulting in N_tot concentrations of 0–50% higher compared to their acidified counterparts. As a consequence, molar C/N ratios derived from the analysis of C_org and N_tot in the acidified sample ranged between 6 to 11, while the N_tot separate analysis reduced C/N ratios to 6 to 8. It is suggested that the addition of sulphurous acid to eliminate inorganic carbon volatilises nitrogenous organic matter.     

Coulometric total carbon dioxide analysis for marine studies: maximizing the performance of an automated gas extraction system and coulometric detector

A global survey of the distribution of dissolved CO₂ taking advantage of sampling opportunities provided by the World Ocean Circulation Experiment: World Hydrographic Program (WOCE-WHP) is being carried out through 1995. Goals include the measurement of oceanic inorganic carbon transport and the development of a data base from which future fossil-fuel CO₂ build-up can be monitored. The analytical method selected for total carbon dioxide (C_T) is gas extraction of acidified seawater with coulometric titration of the acid formed by the resultant carbon dioxide and monoethanolamine. To combine high accuracy and precision (± 1.5 μmol/kg for C_T ≥ 2000 μmol/kg) with a high rate of analysis, we have modified an automated single-parameter system. Following prototype development between 1987 and 1990, an instrument emerged with the acronym Somma standing for single-operator multiparameter metabolic analyzer. Improved functional and operating procedures have integrated electronic calibration, CO₂ gas calibration, and sample analysis with automated pressure, temperature, and conductivity (salinity) sensing into a single convenient transportable package.     

太平洋中低纬海水中的二氧化碳分布特征及其与海洋环境条件的关系

根据1986年11月至1990年6月进行的中美热带西太平洋海-气相互作用(TOGA)联合考查和1995年10月至1996年6月“中日副热带联合调查”期间获得的14个航次大气和海水CO₂的观测资料,给出了主要观测海区CO₂的源与汇的分布特征:在赤道地区5°N~5°S,130°~165°E观测到的表面水中二氧化碳分压的值超过了大气中二氧化碳分压1.5~4.5 Pa,结果表明该海区对大气CO₂而言是源,但是该值远小于在中赤道测到的+9.1 Pa和在东赤道太平洋所测的+15 Pa的值.由此表明热带太平洋CO₂源的强度是向西减弱的.副热带海区在秋季对大气CO₂而言是较强的源,春季是汇.对影响海水CO₂变化的主要因素温度、盐度等进行了讨论,表明CO₂的分布变化直接受海流、水团、黑潮和ENSO事件影响.     

胶州湾水体中的二氧化碳体系

采用库仑滴定法测定了胶州湾海域４个航次的总二氧化碳,根据测定的总二氧化碳的数据计算了二氧化碳各分量的含量及二氧化碳分压,得到了胶州湾水体中二氧化碳体系的平面分布、垂直分布及周日变化规律,并对结果进行了初步探讨 。     

Measurements of carbon dioxide in the Seto Inland Sea of Japan

The carbon dioxide in seawater (pCO₂) was measured in the Seto Inland Sea of Japan using newly developed equilibrator instrument designed to be free from the correction for addition or extraction of the carbon dioxide from carrier gas. The temperature dependence of pCO₂ was about 4.5%pCO₂/°C for a single seawater sample which was processed as free from biological activity and change in total carbon dioxide content during an experiment. The decrease in pCO₂ during daylight hours due to the photosynthetic fixation was about 30% of the daily mean of pCO₂ during warm months and about 15% during cold months. The effect of carbon dioxide exchange between air and seawater on pCO₂ was about 0.6 ppm in August and about 0.1 ppm in March. This is negligible small compared with the daily oscillation of carbon dioxide in seawater.     

<Emphasis Type="Italic">In situ</Emphasis> Enclosure Experiment Using a Benthic Chamber System to Assess the Effect of High Concentration of CO<Subscript>2</Subscript> on Deep-Sea Benthic Communities

In order to evaluate the environmental impact associated with sequestration of carbon dioxide in the deep sea, a free fall type field experimental device, the benthic chamber, was developed. In situ experiments to expose deep-sea communities to elevated concentrations of carbon dioxide (average of 20,000 ppm, 5,000 ppm and control) were carried out using this device 3 times, viz., in the winter of 2002 and in the spring and the summer of 2003, in the Kumano Trough at a depth of 2,000 m. In the long-term experiments (about two weeks in winter of 2002 and summer of 2003), the abundance of meiobenthos declined whereas that of bacteria increased under the condition of 20,000 ppm carbon dioxide compared with the control. Among meiofauna, the abundance of foraminifers at the same concentration of carbon dioxide became less than the control even in the short-term (3 days in spring of 2003) experiment, suggesting that organisms with a calcium carbonate exoskeleton are more sensitive to the raised concentration of carbon dioxide. The respiration rate of the benthic community exposed to 20,000 ppm was lower in the early stage of the experiment than in the latter half, whereas it was opposite under the condition of 5,000 ppm. The increase of biological activity in the 20,000 ppm exposure group is probably due to an increase of bacteria adapted to high carbon dioxide concentrations. The present results suggest that the influence of carbon dioxide on the deep-sea benthic ecosystem does not follow a simple, linear relationship with concentration.     

Investigation of the mechanism of the long-term evolution of the carbon cycle in the ecosystem of the Sevastopol bay

We analyze the components of the carbon system of the Sevastopol bay waters and the balance of main sediment-forming substances using the data of field investigations in 1998–2008. The interannual variations of total inorganic carbon and the equilibrium partial pressure of carbon dioxide in the bay water are noted. An increase in the flux of carbon dioxide into the bay and in the content of organic carbon in bottom sediments is revealed, and an explanation of this phenomenon is given. The priority accumulation of organic carbon in the sediments of the bay is established. We assess the interannual variation in the relative abundances of organic and inorganic carbon as an index of the carbon cycle stability.     

Analysis of seawater for dissolved cadmium, copper and lead: An intercomparison of voltammetric and atomic absorption methods

An intercomparison study of voltammetric and atomic absorption spectrometric methods for determining cadmium, lead and copper in seawater samples was conducted. The voltammetric approach utilizes differential pulse anodic stripping voltammetry using a rotating, glassy carbon, mercury film electrode under conditions developed to minimize contamination sources and to enhance sensitivity for seawater matrices. The atomic absorption approach involves a concentration step using either an organic solvent extraction of metal dithiocarbamate chelates or a Chelex-100 column with detection by graphite furnace atomic absorption spectrometry. Similar and consistent results were obtained using both methods for the three trace metals studied on a wide range of natural seawater samples. Both methods are comparable in sensitivity for cadmium and copper, however the voltammetric method is better suited for the analysis of lead in seawater because of its enhanced sensitivity and low blank. An advantage of the voltammetric approach is its amenability towards real-time shipboard analysis.     

Air-sea carbon fluxes and their controlling factors in the Prydz Bay in the Antarctic

The Prydz Bay in the Antarctic is an important area in the Southern Ocean due to its unique geographic feature. It plays an important role in the carbon cycle in the Southern Ocean. To investigate the distributions of carbon dioxide in the atmosphere and surface seawater and its air-sea exchange rates in this region, the Chinese National Antarctic Research Expedition （CHINARE） had set up several sections in the Prydz Bay. Here we present the results from the CHINARE-XVI cruises were presented onboard R/V Xue/ong from November 1999 to April 2000 and the main driving forces were discussed controlling the distributions of partial pressure of carbon dioxide. According to the partial pressure of carbon dioxide distributions, the Prydz Bay can be divided into the inside and outside regions. The partial pressure of carbon dioxide was low in the inside region but higher in the outside region during the measurement period. This distribution had a good negative correlation with the concentrations of ehlorophyll-a in general, suggesting that the partial pressure of carbon dioxide was substantially affected by biological production. The results also indicate that the biological produetion is most likely the main driving force in the marginal ice zone in the Southern Ocean in summer. However, in the Antarctic divergence sector of the Prydz Bay （about 64°S）, the hydrological processes become the controlling factor as the sea surface partial pressure of carbon dioxide is much higher than the atmospheric one due to the upwelling of the high DIC CDW, and this made the outside of Prydz Bay a source of carbon dioxide. On the basis of the calculations, the CO2 flux in January （austral summer） was -3.23 mmol/（m^2 · d） in the inner part of Prydz Bay, i.e. , a sink of atmospheric CO2, and was 0.62 mmol/（m^2 · d） in the outside part of the bay, a weak source of atmospheric CO2. The average air-sea flux of CO2 in the Prydz Bay was 2.50 mmol/（m^2 · d）.     

二氧化碳海洋倾废的研究进展

简要回顾了二氧化碳深海倾废设想提出的背景及其理论依据,阐述了实施二氧化碳深海倾废的可行性,着重讨论了CO2在深海的水合化过程以及最新的现场实验结果。分析了CO2海洋倾废对深海环境和生态系统的潜在影响。在与其他二氧化碳倾废方式进行比较的基础上,对今后的发展进行了展望。     

海洋碱性矿物增汇技术发展方向研究

工业革命以来,近1/3人为排放的二氧化碳被海洋吸收,海洋负排放潜力巨大。海洋碱化技术被认为是最具有固碳潜力的海洋负排放技术之一。硅酸盐碱性矿物橄榄石风化速率高,在自然界中具有广泛的分布。海水增汇效率受到橄榄石的溶解速率、扩散速率等因素的影响。基于近海橄榄石海上反应平台,利用清洁能源将橄榄石破碎、研磨加速其溶解,再由海流将高碱度海水进行扩散促进毗邻海域对大气二氧化碳吸收的方法具有广阔的应用前景。随着我国近海油气资源的开发,基于海上油气平台发展橄榄石碱化增汇技术,降低海上碱化反应平台基建成本的同时,可捕集油气生产过程中的二氧化碳,随碱化后海水入海,进一步提高碱性矿物增汇技术的碳封存效能。     

The free amino acid composition of seawater obtained without desalting and preconcentration

A conventional amino acid analyzer was modified to allow detection of dissolved free amino acids in a direct injection of 0.5 to 2.0 ml of seawater. The amino acids were monitored fluorimetrically by reaction with o-phthaldialdehyde after column chromatography. The accuracies of two commonly employed desalting methods, cation exchange resin and copper Chelex, were determined by comparison with the direct injection method. After correcting the results of the desalting methods for the procedural blank and recovery rate for each individual amino acid, the amino acid compositions on a mole percent basis as determined by these methods resembled approximately the true composition determined by direct injection. However, on an absolute basis the cation resin method overestimates and the copper Chelex method underestimates the total amount of dissolved free amino acids. The reasons for these discrepancies are discussed. Using the direct injection method, the spectra of dissolved free amino acids in surface seawater samples from different locations were determined. As opposed to the relatively uniform patterns reported in most past investigations, the amino acid spectra found were highly variable. In a number of samples, the acidic amino acids dominated the spectra. Valine was also high in many samples. In a depth profile the deep samples were dominated by arginine. Application of the method to real-time shipboard analyses of dissolved free amino acids is discussed.