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1.
采用化学沉淀法成功制备了Cu2+/SnO2复合纳米光催化剂,采用XRD、SEM等测试手段对复合纳米光催化剂的粒径、形态等进行表征。在紫外光条件下,分别改变催化剂掺杂比、催化剂煅烧温度、催化剂投加量、柴油初始含量和光照时间等单因素,探究不同条件对Cu2+/SnO2复合纳米光催化剂降解海洋柴油污染物的影响。结果表明,自制复合纳米光催化剂可以有效降解海水中的柴油污染物,在紫外光作用下,于400℃下煅烧Cu/Sn掺杂比为0. 03的Cu2+/SnO2复合纳米光催化剂、投加量为0. 2 g/dm3、柴油初始含量为0. 15 g/dm3、H2O2溶液含量为0. 2 g/dm3、溶液的p H为7、光照时间3 h时效果最好,海水中柴油的去除率最高,达到86. 98%。Cu2+/SnO2复合纳米光催化剂用聚丙烯纳米球负载后可以实际应用于海洋中,便于回收。 相似文献
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This paper evaluates the simultaneous measurement of dissolved gases (CO2 and O2/Ar ratios) by membrane inlet mass spectrometry (MIMS) along the 180° meridian in the Southern Ocean. The calibration of pCO2 measurements by MIMS is reported for the first time using two independent methods of temperature correction. Multiple calibrations and method comparison exercises conducted in the Southern Ocean between New Zealand and the Ross Sea showed that the MIMS method provides pCO2 measurements that are consistent with those obtained by standard techniques (i.e. headspace equilibrator equipped with a Li–Cor NDIR analyser). The overall MIMS accuracy compared to Li–Cor measurements was 0.8 μatm. The O2/Ar ratio measurements were calibrated with air-equilibrated seawater standards stored at constant temperature (0 ± 1 °C). The reproducibility of the O2/Ar standards was better than 0.07% during the 9 days of transect between New Zealand and the Ross Sea.The high frequency, real-time measurements of dissolved gases with MIMS revealed significant small-scale heterogeneity in the distribution of pCO2 and biologically-induced O2 supersaturation (ΔO2/Ar). North of 65°S several prominent thermal fronts influenced CO2 concentrations, with biological factors also contributing to local variability. In contrast, the spatial variation of pCO2 in the Ross Sea gyre was almost entirely attributed to the biological utilization of CO2, with only small temperature effects. This high productivity region showed a strong inverse relationship between pCO2 and biologically-induced O2 disequilibria (r2 = 0.93). The daily sea air CO2 flux ranged from − 0.2 mmol/m2 in the Northern Sub-Antarctic Front to − 6.4 mmol/m2 on the Ross Sea shelves where the maximum CO2 influx reached values up to − 13.9 mmol/m2. This suggests that the Southern Ocean water (south of 58°S) acts as a seasonal sink for atmospheric CO2 at the time of our field study. 相似文献
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生物固氮作用是一个重要的海洋新氮来源，在海洋生物地球化学循环中扮演着不可替代的角色。基于稳定同位素（15N2）示踪吸收法，是目前直接测定海洋生物固氮速率最有效的手段。其中，高效、洁净地将15N2引入海水培养体系，并准确定量培养体系底物的同位素示踪水平，是同位素示踪吸收法准确获取固氮速率的关键。本研究针对15N2同位素示踪剂引入这一关键环节进行了探讨，确认改进气泡法是将15N2引入海水培养体系的首选操作。在对培养体系造成的较小扰动的情况下，可将培养体系氮气底物的15N原子丰度提升至10%以上，相对于另一种导入同位素示踪剂的手段——预溶解海水法，改进气泡法将培养瓶中氮气底物的15N原子丰度提升了近200%。此外，改进气泡法还具有最小化痕量金属沾污、操作简便等优点。将改进气泡法结合与稳定同位素比值质谱测定结合，是准确测定水体生物固氮速率的推荐方法。 相似文献
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This paper reports that stoichiometric, amorphous, and uniform Er2O3 films are deposited on Si(001) substrates by a radio frequency magnetron sputtering technique. Ellipsometry measurements show that the refractive index of the Er2O3 films is very close to that of a single layer antireflection coating for a solar cell with an air surrounding medium during its working wavelength. For the 90-nm-thick film, the reflectance has a minimum lower than 3% at the wavelength of 600 nm and the weighted average reflectances (400--1000 nm) is 11.6%. The obtained characteristics indicate that Er2O3 films could be a promising candidate for antireflection coatings in solar cells. 相似文献
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Coastal upwelling systems are regions with highly variable physical processes and very high rates of primary production and very little is known about the effect of these factors on the short-term variations of CO2 fugacity in seawater (fCO2w). This paper presents the effect of short-term variability (<1 week) of upwelling–downwelling events on CO2 fugacity in seawater (fCO2w), oxygen, temperature and salinity fields in the Ría de Vigo (a coastal upwelling ecosystem). The magnitude of fCO2w values is physically and biologically modulated and ranges from 285 μatm in July to 615 μatm in October. There is a sharp gradient in fCO2w between the inner and the outer zone of the Ría during almost all the sampling dates, with a landward increase in fCO2w.CO2 fluxes calculated from local wind speed and air–sea fCO2 differences indicate that the inner zone is a sink for atmospheric CO2 in December only (−0.30 mmol m−2 day−1). The middle zone absorbs CO2 in December and July (−0.05 and −0.27 mmol·m−2 day−1, respectively). The oceanic zone only emits CO2 in October (0.36 mmol·m−2 day−1) and absorbs at the highest rate in December (−1.53 mmol·m−2 day−1). 相似文献
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An improved model is presented for the calculation of the solubility of carbon dioxide in aqueous solutions containing Na+, K+, Ca2+, Mg2+, Cl−, and SO42− in a wide temperature–pressure–ionic strength range (from 273 to 533 K, from 0 to 2000 bar, and from 0 to 4.5 molality of salts) with experimental accuracy. The improvements over the previous model [Duan, Z. and Sun, R., 2003. An improved model calculating CO2 solubility in pure water and aqueous NaCl solutions from 273 to 533K and from 0 to 2000 bar. Chemical Geology, 193: 257–271] include: (1) By developing a non-iterative equation to replace the original equation of state in the calculation of CO2 fugacity coefficients, the new model is at least twenty times computationally faster and can be easily adapted to numerical reaction-flow simulator for such applications as CO2 sequestration and (2) By fitting to the new solubility data, the new model improved the accuracy below 288 K from 6% to about 3% of uncertainty but still retains the high accuracy of the original model above 288 K. We comprehensively evaluate all experimental CO2 solubility data. Compared with these data, this model not only reproduces all the reliable data used for the parameterization but also predicts the data that were not used in the parameterization. In order to facilitate the application to CO2 sequestration, we also predicted CO2 solubility in seawater at two-phase coexistence (vapor–liquid or liquid–liquid) and at three-phase coexistence (CO2 hydrate–liquid water–vapor CO2 [or liquid CO2]). The improved model is programmed and can be downloaded from the website http://www.geochem-model.org/programs.htm. 相似文献
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Concentration and stable isotopic compositions (δ
18O) of dissolved O2 were measured in seawater samples collected from the Philippine Sea in June 2006. The in-situ O2 consumption rate and the isotopic fractionation factor (α
r
) during dissolved O2 consumption were obtained from field observations by applying a vertical one-dimensional advection diffusion model to the
deep water mass of about 1000–4000 m. The average O2 consumption rate and α
r
were, respectively, 0.11 ± 0.07 μmol kg−1yr−1 and 0.990 ± 0.001. These estimated values agree well with values from earlier estimations of Pacific deep water. The in-situ O2 consumption rates are two or more times higher north of 20°N, although the value of α
r
was not significantly different between the north and south. Its levels varied rapidly in the water mass of less about 2000
m depth. These results suggest that organic matter from the continent imparts a meaningful contribution to the upper water
in the northern part of the area; it might produce the strong O2 minimum that is evident in the water mass from about 1000–2000 m in the northern part of the Philippine Sea. 相似文献
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The generalised gradient approximation based on density functional theory is used to study the structural and electronic properties of the endohedral fullerene dimer (N2@C60)2. Four N atoms sit at the cage centres in the form of two N_2 molecules. The density of states and Mulliken charge analysis explore that the energy levels from -6 to -10 eV are mainly influenced by the N2 molecules. 相似文献
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利用15 N示踪法实测南海水体反硝化速率的研究发现,培养水样在长时间密闭放置过程中也会受到外界空气的污染,且其29N2/28N2比值恒定为0.007 35。根据空气背景中29N2/28N2比值恒定的特征,提出基于质量平衡关系校正空气N2污染的方法,通过将样品实测29N2浓度扣除由外界空气贡献的29N2浓度,可获得由生物反硝化作用所产生的29N2准确浓度,进而可计算出准确的反硝化速率。经空气29N2背景校正后,29N2浓度的偏差明显小于未经校正的结果,且29N2浓度与培养时间之间的线性相关性显著加强,凸显出空气29N2背景校正是获取准确反硝化速率的关键。鉴于15 N示踪法已被广泛应用于海洋水体与沉积物反硝化速率的测定中,所提出的空气29N2背景校正方法具有重要的意义。 相似文献
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The effect of the orientation on the magnetostriction in Fe81Ga19 alloy has been investigated experimentally and theoretically. The Fe81Ga19 [001] and [110] oriented crystals were prepared and the magnetostriction was measured under different pre-stress. The saturation magnetostriction of the [001] oriented crystal increases from 170×10-6 to 330×10-6 under the pre-stress from 0 to 50 MPa. The [110] oriented crystal has a saturation magnetostriction from 20×10-6 to 140×10-6 with the compressive pre-stress from 0 to 40 MPa. The magnetostriction of [001] and [110] oriented crystals has been simulated based on the phenomenological theory. The domain rotation path has been determined and the resultant magnetostriction calculated under different pre-stress. The experimental and simulated results both show that the [001] oriented crystal exhibits better magnetostriction than [110] oriented crystal. The enhancement of the saturation magnetostriction by the compressive pre-stress in the [110] oriented crystal is higher than that in the [001] oriented crystal. 相似文献
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The mechanisms regulating N2O production in an estuarine sediment (Tama Estuary, Japan) were studied by comparing the change in N2O production with those in nitrification and denitrification using an experimental continuous-flow sediment–water system with15N tracer (15N-NO−3 addition). From Feburary to May, both nitrification and denitrification in the sediment increased (246 to 716 μmol N m−2 h−1and 214 to 1260 μmol N m−2 h−1, respectively), while benthic N2O evolution decreased slightly (1560 to 1250 nmol N m−2 h−1). Apparent diffusion coefficients of inorganic nitrogen compounds and O2at the sediment–water interface, calculated from the respective concentration gradients and benthic fluxes, were close to the molecular diffusion coefficients (0·68–2·0 times) in February. However, they increased to 8·8–52 times in May except for that of NO−2, suggesting that the enhanced NO−3 and O2supply from the overlying water by benthic irrigation likely stimulated nitrification and denitrification. Since the progress of anoxic condition by the rise of temperature from February to May (9 to 16 °C) presumably accelerated N2O production through nitrification, the observed decrease in sedimentary N2O production seems to be attributed to the decrease in N2O production/occurrence of its consumption by denitrification. In addition to the activities of both nitrification and denitrification, the change in N2O metabolism during denitrification by the balance between total demand of the electron acceptor and supply of NO−3+NO−2 can be an important factor regulating N2O production in nearshore sediments. 相似文献
14.
T. Yoshinari M. A. Altabet S. W. A. Naqvi L. Codispoti A. Jayakumar M. Kuhland A. Devol 《Marine Chemistry》1997,56(3-4)
Nitrous oxide (N2O) is a trace gas that is increasing in the atmosphere. It contributes to the greenhouse effect and influences the global ozone distribution. Recent reports suggest that regions such as the Arabian Sea may be significant sources of atmospheric N2O.In the ocean, N2O is formed as a by-product of nitrification and as an intermediary of denitrification. In the latter process, N2O can be further reduced to N2. These processes, which operate on different source pools and have different magnitudes of isotopic fractionation, make separate contributions to the 15N and18O isotopic composition of N2O. In the case of nitrification in oxic waters, the isotopic composition of N2O appears to depend mainly on the 15N/14N ratio of NH+4 and the 18O/16O ratio of O2 and H2O. In suboxic waters, denitrification causes progressive 15N and 18O enrichment of N2O as a function of degree of depletion of nitrate and dissolved oxygen. Thus the isotopic signature of N2O should be a useful tool for studying the sources and sinks for N2O in the ocean and its impact on the atmosphere.We have made observations of N2O concentrations and of the dual stable isotopic composition of N2O in the eastern tropical North Pacific (ETNP) and the Arabian Sea. The stable isotopic composition of N2O was determined by a new method that required only 80–100 nmol of N2O per sample analysis. Our observations include determinations across the oxic/suboxic boundaries that occur in the water columns of the ETNP and Arabian Sea. In these suboxic waters, the values of δ15N and δ18O increased linearly with one another and with decreasing N2O concentrations, presumably reflecting the effects of denitrification. Our results suggest that the ocean could be an important source of isotopically enriched N2O to the atmosphere. 相似文献
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南海东北部春季海表pCO_2分布及海-气CO_2通量 总被引：1，自引：1，他引：0
2013年南海东北部春季共享航次采用走航观测方式,现场测定了表层海水和大气的二氧化碳分压(pCO2)及相应参数。结合水文、化学等同步观测要素资料,对该海域pCO2的分布变化进行了探讨。结果表明,陆架区受珠江冲淡水、沿岸上升流及生物活动的影响,呈现CO2的强汇特征;吕宋海峡附近及吕宋岛西北附近海域受海表高温、黑潮分支"西伸"、吕宋岛西北海域上升流等因素影响,呈现强源特征。根据Wanninkhof的通量模式,春季整个南海东北部海域共向大气释放约4.25×104 t碳。 相似文献
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Vertical profiles of dissolved and particulate 210Po and 210Pb were measured across the redox transition zone at Station F1 in Framvaren Fjord, Norway. In this fjord, a sharp decrease in pH above the O2/H2S interface facilitates the aerobic dissolution of MnO2. In contrast, Fe(II) concentrations begin to increase only at the O2/H2S interface depth. Activity profiles reveal that dissolved 210Po and 210Pb are sequestered efficiently by particulates in surface waters. As polonium-210 and lead-210 activities descend down into the aerobic manganese reduction (AMR) zone, they are remobilized during the reductive dissolution of the carrier phase oxyhydroxides. Both 210Po and 210Pb are highly enriched at the O2/H2S interface where an active community of microbes, such as anoxygenic phototrophs (e.g., Chromatium, Chlorobium sp.), thrives. The coincident peaks in 210Po, 210Pb and microbial biomass suggest a strong biological influence on the behavior of these radionuclides. There is a strong covariance between the vertical distribution of Mn and Pb, indicating that their redox cycling is closely coupled and is likely microbially mediated. 相似文献
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微藻固碳是一种新型节能减排技术，具有长期可持续发展的潜力。本文对两株富油微藻（球等鞭金藻和微拟球藻）进行了富碳培养下生长特性及中性脂积累特性的研究。两株富油微藻的最佳培养条件为10%CO2浓度和f培养基。本研究对两株富油微藻的最大生物量产率、总脂含量、最大油脂产率、微藻的C含量和CO2固定率进行了测定。球等鞭金藻的各参数指标分别为：142.42±4.58g/（m2·d），39.95%±0.77%，84.47±1.56g/（m2·d），45.98%±1.75%和33.74±1.65g/（m2·d）。微拟球藻的各参数指标分别为：149.92±1.80g/（m2·d），37.91%±0.58%，89.90±1.98g/（m2·d），46.88%±2.01%和34.08±1.32g/（m2·d）。实验结果显示，两株海洋微藻均属于高固碳优良藻株，适合应用于微藻烟气减排技术开发，具备用于海洋生物质能耦合CO2减排开发的潜力。 相似文献
19.
Y.M. Astor M.I. Scranton F. Muller-Karger R. Bohrer J. García 《Marine Chemistry》2005,97(3-4):245-261
Monthly seawater pH and alkalinity measurements were collected between January 1996 and December 2000 at 10°30′N, 64°40′W as part of the CARIACO (CArbon Retention In A Colored Ocean) oceanographic time series. One key objective of CARIACO is to study temporal variability in Total CO2 (TCO2) concentrations and CO2 fugacity (fCO2) at this tropical coastal wind-driven upwelling site. Between 1996 and 2000, the difference between atmospheric and surface ocean CO2 concentrations ranged from about − 64.3 to + 62.3 μatm. Physical and biochemical factors, specifically upwelling, temperature, primary production, and TCO2 concentrations interacted to control temporal variations in fCO2. Air–sea CO2 fluxes were typically depressed (0 to + 10 mmol C m− 2 day− 1) in the first few months of the year during upwelling. Fluxes were higher during June–November (+ 10 to 20 mmol C m− 2 day− 1). Fluxes were generally independent of the slight changes in salinity normally seen at the station, but low positive flux values were seen in the second half of 1999 during a period of anomalously heavy rains and land-derived runoff. During the 5 years of monthly data examined, only two episodes of negative air–sea CO2 flux were observed. These occurred during short but intense upwelling events in March 1997 (−10 mmol C m− 2 day− 1) and March 1998 (− 50 mmol C m− 2 day− 1). Therefore, the Cariaco Basin generally acted as a source of CO2 to the atmosphere in spite of primary productivity in excess of between 300 and 600 g C m− 2 year− 1. 相似文献
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CO2升高和阳光紫外辐射对坛紫菜生长和光合特性的耦合效应 总被引：1，自引：0，他引：1
大气CO2持续升高,导致溶入海水中的CO2增多,海水表层的H+浓度增加,从而引起海洋酸化。为了探讨近岸定生大型海藻对这种环境变化的响应,本文选择经济海藻坛紫菜为实验材料,研究海洋酸化与紫外辐射对藻体生长以及光合特性的影响。实验分两个CO2处理,分别为正常空气水平(390 ppmv)和高CO2水平(800 ppmv); 三种辐射处理,分别为全波长辐射(PAB)、滤除紫外线B(PA)和仅接受可见光处理(PAR)。研究结果表明,CO2培养下的坛紫菜,在仅有可见光(P)或者同时有紫外线A(PA)存在的情况下,显著促进藻体的生长;但在全波长辐射处理下(PAB),这种作用不明显。高CO2降低了藻体在P和PA处理下的光合作用速率,但对PAB处理作用不显著。高CO2处理下的藻体,UV-B显著降低了全波长辐射下藻体紫外吸收物质的含量,但在正常CO2水平下,紫外辐射的作用不显著。这表明高CO2导致的生长优势被紫外辐射的负面效应所抵消,在全球变化的过程中,紫外辐射的进一步加强在海洋酸化的背景下甚至有可能降低坛紫菜的产量。 相似文献