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1.
Satellite instruments for the routine global monitoring of NO2 in the atmosphere—the Global Ozone Monitoring Experiment (GOME) on the ERS-2 satellite, the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) on the ENVISAT satellite, the Ozone Monitoring Instrument (OMI) on the AURA satellite, and the GOME-2 on the MetOp satellite—are briefly described. It is shown that the error of measuring the NO2 total column amount (∼10% for the background conditions in the troposphere) substantially increases in regions subject to anthropogenic pollution. Examples of practically using multiyear satellite measurements for the regional monitoring of NO2 in the troposphere are presented, including mapping the tropospheric NO2 in Russia, identifying the weekly and annual cycles in tropospheric NO2 variations for megalopolises (St. Petersburg, Moscow, Paris), and estimating the long-term linear trend in 1995–2007.  相似文献   

2.
The results of spectroscopic measurements of tropospheric NO2 content performed on a closed route along the circular road around the city of St. Petersburg in 2012, 2014, and 2015 are presented. A procedure for determining the integral emission of NO x based on the data of measurements on the route enveloping the sources under study is described. An analysis of the experimental data together with the results of a numerical simulation of air pollutant dispersion (the HYSPLIT model) provided an estimate of the total volume of NO x emitted by all sources located inside the circular road. The average emission rate of NO x according to the sources of the megacity of St. Petersburg is 57000 t/yr, which correlates satisfactorily with the official data of a municipal inventory of the sources of air pollution (62000–63 000 t/yr).  相似文献   

3.
A one-dimensional ionic-photochemical model of the gaseous composition of the atmosphere that describes the formation of the D layer of the ionosphere is presented. Based on this model, the vertical profiles of the concentration of electrons and ions in the D layer of the ionosphere were calculated, as were the vertical distributions of minor gaseous constituents in the atmosphere up to a height of 86 km for undisturbed conditions and after a powerful solar proton events (SPE) at the end of October 2003. The calculations showed that SPEs significantly increase NOx in the mesosphere of polar latitudes. In the lower mesosphere of polar caps, the NOx mixing ratio increases by 20–50 ppb; in the upper mesosphere it increases by 100 ppb and more. High NOx levels in zones of their formation can be retained for several weeks, producing a long-term but comparatively small ozone decrease in the lower mesosphere. The main ozone decrease is caused by a short-term HOx increase after SPEs and is also of a short-term character in the conditions of the illuminated mesosphere. After the SPE in October 2003, model calculations yield an ozone concentration decrease by 40% in the middle and upper mesosphere at 75 ° S and by 70% at the same heights at 70 ° N. The results of modeling NOx and O3 changes after the SPE in October 2003 agree well with the data of satellite measurements. The changes in minor gases of the mesosphere after the SPE obtained in the model with parameterized sources of HOx and NOx are compared with their changes obtained in the complete ionic-photochemical model. The changes in HOx, NOx, and O3 coincide rather well, whereas the changes in ClO noticeably differ, especially in the lower mesosphere. Thus, at a height of about 60 km, the parameterized photochemical model underestimated twofold the ClO formation after the SPE.  相似文献   

4.
This study indicates that environmental policy interventions significantly influence the innovation processes for reducing the emissions of marine engine technology. Several different types of interventions have been important and the effect is not directly proportional to the strength or spatial coverage of the intervention. Despite its relative weakness, the MARPOL rule on NOx emissions has contributed to technology development. We also show that the rise of environmental issues in other fields has had a marked effect on the development of the marine sector and that relatively local interventions can influence innovation even in an international sector like marine transport.  相似文献   

5.
Concentrations of nutrients (NO3, NO2, Si(OH)4, PO4 and dissolved inorganic carbon (DIC) were measured in a series of seawater samples collected over approximately 15 months in 2005 and 2006 by an automatic water sampler (Remote Access Sampler, RAS) in the Northwestern North Pacific. Seasonal variability and concentrations of NO3 + NO2 (NOx and Si(OH)4 were comparable to previous shipboard observations, although there were small errors associated with measurements of PO4 and DIC. Concentrations of these nutrients began to decrease in late April. After the end of June, NOx and Si(OH)4 decreased rapidly, with large fluctuations. After October, these nutrients increased again until late spring 2006. The ratio of the decrease of Si(OH)4 to that of NOx suggests that numbers of biogenic opal-producing creatures, such as diatoms, increased after the end of June. This conclusion was supported by a rapid increase in biogenic opal flux recorded in a sediment trap at 150 m. The relationship between NOx concentrations at the RAS depth of 35 m and NOx integrated over the upper 100 m was determined using previous shipboard hydrocast data. This relationship was used to estimate integrated mixed layer NOx concentration from RAS data. Estimated new production based on seasonal drawdown of integrated NOx averaged approximately 156 mg-C m−2day−1 annually, which agrees with previous estimates. Thus, an automatic seawater sampler that documents annual maximum and minimum nutrient concentrations and episodic events such as storms and spring blooms, which might be missed by an ordinary research vessel, will contribute to time-series observations of nutrients and, by extension, biological pump activity.  相似文献   

6.
为获得反硝化脱氮效率较好的菌株,实验从海水螺旋藻培养体系中分离获得一株嗜碱兼性好氧反硝化菌, 通过观察细菌形态以及16S rRNA基因序列的同源性分析, 鉴定该菌株为海杆菌属, 命名为Marinobacter sp. B3。为明确该海杆菌的反硝化性能及氮转化途径, 研究开展了溶解氧(DO), 碳氮摩尔比(C/N), pH和温度等不同单因素对反硝化性能影响实验和氮平衡实验。单因素影响实验结果表明, 当硝酸钾(KNO3)作为唯一氮源, NO3--N的初始浓度为100 mg/L, 盐度32, 振荡速度为150 r/min (初始DO质量浓度是5.6 mg/L), C/N=10, pH=8.0±0.2, 温度为35 °C时, 可获得最大脱氮效果。氮平衡实验结果得出, 在好氧环境下, 有20.11%的NO3--N转化为胞内氮, 5.58 mg/L的NO3--N转化为其他形态(NO2--N、NO4+-N和有机氮), 74.72%转化为N2释放; 厌氧环境下, 有26.65%的NO3--N转化为胞内氮, 72.86%的NO3--N转化为气态产物释放。最终实验结果表明, Marinobactersp. B3在好氧和厌氧条件下, 48 h对NO3--N的去除率分别为99.89%和93.80%, 具有较好的反硝化脱氮能力, 且在好氧条件下NO3--N去除效率更高, 在海水工厂化循环水养殖尾水处理方面具有良好的应用前景。  相似文献   

7.
The space-time variability of the fields of CO, NO2, and O3 concentrations and contents in the troposphere of northwestern Russia is analyzed on the basis of experimental data and the results of numerical modeling. The influence that the St. Petersburg emission has on the concentrations and contents of CO, NO2, and O3 in the troposphere is estimated for March 2006. A comparison of the measurements of the total CO content and the tropospheric NO2 content with the results of modeling showed a qualitative and, in come cases, quantitative agreement between the results of calculations and experimental data. When synoptic conditions are determined, the St. Petersburg train can be detected at a distance of more than 300 km, which can affect the atmospheric air quality in adjacent countries.  相似文献   

8.
The carbon to nitrogen (C:N) stoichiometry of phytoplankton production varied significantly during the spring–summer bloom in the North Water Polynya (NOW), from April through July 1998. The molar ratio of particulate organic carbon (POC) to nitrogen (PON) production by phytoplankton (ΔPOC:ΔPON) increased from 5.8 during April through early June to 8.9 in late June and July. The molar dissolved inorganic carbon (DIC) to nitrate+nitrite (NO3) drawdown ratio (ΔDIC: ΔNO3) increased from 6.7 in April and May, to 11.9 in June (no estimate for July because of ice melting). The discrepancy between ΔPOC:ΔPON and ΔDIC:ΔNO3 was likely due to dissolved organic carbon (DOC) production. Increased ΔPOC:ΔPON of phytoplankton and surface water ΔDIC:ΔNO3 throughout the phytoplankton blooms resulted from changes in physical properties of the upper water column, such as reduced thickness of the surface mixed layer that exposed phytoplankton to increased photosynthetically available radiation (PAR), accompanied by NO3 depletion. This is expected to have significant effects on the cycling of carbon (C) and nitrogen (N) in pelagic ecosystems, as the increased C:N ratio of organic matter decreases its quality as substrate for grazers and microbial communities. Based on ΔPOC:ΔPON, the ratio of POC to chlorophyll a (Chl) production (ΔPOC:ΔChl) and the relationship between Chl yields and NO3 depletion, we estimate that 71±17% and 46±20% of the depleted NO3 went to PON production in the euphotic zone over the polynya from April to early June, and late June to July, respectively. The remaining NO3 was likely channelled to dissolved organic nitrogen (DON) and heterotrophic bacteria, which were not returned to the dissolved inorganic nitrogen (DIN) pool through recycling during the course of the study. Hence, the autotrophic production of organic N and its recycling by the microbial food web were not coupled temporally.  相似文献   

9.
浒苔对NH+4-N与NO-3-N吸收的相互作用   总被引：1，自引：0，他引：1  
在国内首次研究了大型海洋绿潮藻浒苔(Ulva prolifera)对NH4+-N与NO 3--N两种氮源的选择吸收作用。结果表明:当两种氮源等浓度比例存在时,随着NH4+-N与NO3--N浓度升高,藻体对NH4+-N的吸收速率逐渐升高,而对NO3--N吸收受到抑制;当NO3--N和NH 4+-N高浓度比存在时,藻体对NH4-N的吸收速率随着NO3--N/NH4+-N比例的升高和NH4-N浓度的下降而降低;当NO3--N和NH4+-N低浓度比存在时,藻体对NH+4-N保持较高的吸收速率,而对NO3--N的吸收效率随着NO3--N浓度的降低而降低;浒苔具有同时利用水体中较高浓度的NH+4-N和NO3--N的能力,只有当NH4+-N或NO3--N浓度较低时,才以吸收相对应的氮源为主。这说明浒苔能够快速、大量地吸收水体中氮源,为爆发性增殖贮备物质条件。同时,即便两种氮源同时存在,浒苔对NH+4-N的吸收速率也远高于对NO3--N的吸收速率,因此,控制NH4+-N的大量输入仍是预防浒苔绿潮爆发的关键。  相似文献   

10.
微藻培养过程中氮缺失有利于油脂和生物量的积累,然而不同氮源条件下微藻生长与生物量的研究有限,限制了生物油脂的相关研究。本文研究通过研究南极冰藻Chlamydomonas sp.ICE-L在不同氮源条件下的细胞生长与油脂积累,进一步探究其作为富集油脂微藻的潜力。研究发现：在含有NH4CL的培养基中,Chlamydomonas sp.ICE-L生长速率最大;在含有NH4NO3的条件下,获得了最大干重量0.28 g/L。最高油脂含量0.21 g/g是在缺氮条件下获得,同时得到干重0.24 g/L。在多不饱和脂肪酸的产出方面,NH4NO3和NH4Cl为氮源培养基时要好于缺氮和KNO3培养基,在NH4NO3和NH4Cl为氮源的培养条件下ICE-L胞内C18：3和C20：5的含量高。比较而言,缺氮和KNO3培养基时C16：0、C18：1和C18：2的含量要高。  相似文献   

11.
Degraded diesel oils are commonly used in marine power plants to conform to the demands of shipowners for fuel economy. The burning of these marine fuel oils, which frequently contain various extents of oxides of iron, silicon, calcium, vanadium and potassium, such as Na2SO4, Fe2O3, SiO2, CaO, V2O5, etc., are susceptible to form much more complex compounds of either gaseous or solid phases. The release of these emissions to the environment may cause atmospheric pollution and a health hazard to human beings. Emulsification of a fuel oil with water to produce a micro-water-particles-dispersed-in-oil (W/O) emulsion has been considered as one of the promising techniques to improve combustion characteristics of low-grade marine oils and in turn effectively help to reduce the release of air pollutants. Marine fuel oil A, which approximates ASTM No. 2D oil was used as the test oil and the surfactant Span 80 was used to promote the affinity and integrating force between the components of the emulsion. An emulsifying/homogenizing machine was employed to stir the emulsion mixture of the marine oil, distilled water, surfactant Span 80 and sodium sulfate (Na2SO4) powder of 300 ppm. The mechanically blended emulsion mixture was injected, atomized and burned in an oil-fired furnace using an automatic burner. Burning gas composition, burning efficiency and gas temperature were measured and analyzed. Compared to neat marine diesel oil, W/O emulsions had higher combustion efficiencies, higher concentrations of O2 and SO2, while gas temperatures were lowered and CO and NOx production was reduced. The addition of sodium sulfate decreased combustion efficiency and NOx concentration and increased O2, CO, and SO2 concentrations.  相似文献   

12.
The suggested equation system, including 267 chemical reactions and corresponding parametrizations of disturbances of the electric field and electron temperature, describes the dynamics of the mesosphere composition under the influence of high-altitude discharges (sprites and halos). Based on this system, the ionic disturbance, neutral components, and optical emissions of the night mesosphere caused by the sprites were modeled for a height of 77–85 km. Most attention was paid to the dynamics of disturbances of concentrations of electrons and O 2 + , NO+, H3O+, H5O 2 + , and N 2 + typical of the studied heights. The major chemical reactions leading to the disturbance of ionic contents are determined and the relaxation dynamics of the chemical components is reviewed. The account of the excited atoms and molecules of nitrogen and oxygen allowed us to model the radiation of the sprite flash, calculate the volumetric velocity of the photon emission, and study the influence of the sprite on the neutral components of the mesosphere.  相似文献   

13.
Concentrations of particulate organic nitrogen (PN), dissolved inorganic nitrogen (DIN), and their nitrogen isotope ratios (δ 15N) in the Kiso-Sansen Rivers were determined from monthly observations over the course of a year to assess variations in the form and sources of riverine nitrogen discharged into Ise Bay. The δ 15N values of NO3 − observed in the Kiso-Sansen Rivers showed a logarithmic decreasing trend from 8 to 0‰, which varied with the river discharge, indicating mixing between point sources with high δ 15N and non-point sources with low δ 15N. The influence of isotope fractionation of in situ biogeochemical processes (mainly DIN assimilation by phytoplankton) on δ 15N of NO3 − was negligible, because sufficient concentrations of NH4 + for phytoplankton demand would inhibit the assimilation of NO3 −. A simple relationship between river discharge and δ 15N of NO3 − showed that the fraction of total NO3 − flux arising from point sources increased from 4.0–6.3% (1.1–1.8 tN day−1) during higher discharge (>600 m3 s−1) to 30.2–48.3% (2.6–4.1 tN day−1) during lower discharge (<300 m3 s−1). Riverine NO3 − discharge from the Kiso-Sansen Rivers can explain 75% of the variations in surface NO3 − at the head of Ise Bay over the year.  相似文献   

14.
Atmospheric NO2 content data obtained from regular ground-based measurements of solar IR radiation in the St. Petersburg region using a spectrometer with a high spectral resolution are analyzed. The absorption spectra of the NO2 multiplet in the vicinity of ～2915 cm?1 allow one to obtain data on variations in the stratospheric total content of NO2 in 2009–2011. The accuracy of these data is estimated from their comparison with data obtained from independent ground-based and satellite measurements. The parameters of the seasonal cycle of the stratospheric content of NO2 are estimated. The body of data accumulated during these measurements in the IR region made it possible to isolate the component of a daytime photochemical increase in the stratospheric content of NO2 and estimate its rate.  相似文献   

15.
海水人工湿地系统脱氮效果与基质酶活性的相关性   总被引：1，自引：0，他引：1  
利用海水人工湿地系统处理海水养殖外排水,分析了人工湿地对不同形态氮的净化效果,探讨了人工湿地表层基质酶活性变化及其对系统脱氮效果的影响。选取互花米草作为人工湿地植物,煤渣、珊瑚石和细砂作为人工湿地基质,实验期间连续进水,系统运行稳定。研究结果表明:海水人工湿地系统对氨氮(NH4-N)、亚硝态氮(NO2-N)、硝态氮(NO3-N)、总氮(TN)和可溶性有机氮(DON)去除效果显著,去除率分别为(99.6±0.7)%、(99.9±0.0)%、(98.2±2.0)%、(92.6±1.5)%和(86.1±4.8)%。人工湿地表层基质下行池脱氢酶、硝酸还原酶和脲酶的酶活性均高于上行池,下行池对污染物的去除效果更好。脱氢酶活性与海水人工湿地系统氨氮的去除有关;硝酸还原酶活性影响着海水人工湿地硝态氮的去除;脲酶活性与人工湿地总氮和硝态氮的去除存在明显相关趋势。下行池硝酸还原酶和脲酶的酶活性间具有显著相关性(r=0.76, P0.05)。人工湿地微生物种类丰富,下行池微生物多样性高于上行池,植物根部微生物多样性最高,提高了系统脱氮的效率。上述研究结果将有助于阐明海水人工湿地系统中不同形态氮的迁移转化机理。  相似文献   

16.
Eleven incubation experiments were conducted in the South Atlantic sector of the Southern Ocean to investigate the relationship between new production (ρNO–3), regenerated production (ρNH+4), and total carbon production (ρC) as a function of varying light. The results show substantial variability in the photosynthesis–irradiance (P vs E) parameters, with phytoplankton communities at stations that were considered iron (Fe)-limited showing low maximum photosynthetic capacity (PBmax) and low quantum efficiency of photosynthesis (αB) for ρNO3, but high PBmax and αB for ρNH4, with consequently low export efficiency. Results at stations likely relieved of Fe stress (associated with shallow bathymetry and the marginal ice zone) showed the highest rates of PBmax and αB for ρNO3 and ρC. To establish the key factors influencing the variability of the photosynthetic parameters, a principal components analysis was performed on P vs E parameters, using surface temperature, chlorophyll-a concentration, ambient nutrients, and an index for community size structure. Strong covariance between ambient nitrate (NO3) and αB for ρNO3 suggests that Fe and possibly light co-limitation affects the ability of phytoplankton in the region to access the surplus NO3 reservoir. However, the observed relationships between community structure and the P vs E parameters suggest superior performance by smaller-sized cells, in terms of resource acquisition and Fe limitation, as the probable driver of smaller-celled phytoplankton communities that have reduced photosynthetic efficiency and which require higher light intensities to saturate uptake. A noticeable absence in covariances between chlorophyll-a and αB, between PBmax and αB, and between temperature and αB may have important implications for primary-production models, although the absence of some expected relationships may be a consequence of the small dataset and low range of variability. However, significant relationships were observed between ambient NO3 and αB for ρNO3, and between the light-saturation parameter Ek for ρNO3 and the phytoplankton community’s size structure, which imply that Fe and light co-limitation drives access to the surplus NO3 reservoir and that larger-celled communities are more efficient at fixing NO3 in low light conditions. Although the mean PBmax results for ρC were consistent with estimates of global production from satellite chlorophyll measurements, the range of variability was large. These results highlight the need for more-advanced primary-production models that take into account a diverse range of environmental and seasonal drivers of photosynthetic responses.  相似文献   

17.
Maintaining stable water quality is one of the key processes for recirculating coral aquaculture. Traditional aquarium systems which mainly utilized a nitrification of nitrifying bacteria attached to the surface of massive artificial filter material are difficult to maintain the oligotrophic conditions necessary for coral aquaculture. This study investigated the removal effects of dissolved inorganic nitrogen(ammonia and nitrate) by live rock(LR), a key component in the "Berlin system" coral aquarium. The expression levels of bacterial functional genes, AOA3,amo A and nos Z, were measured on the exterior and interior of LR. The nitrifying and denitrifying bacterial abundance on LR was quantified and the nitrogen nutrient regulatory effects of LR were evaluated. The results demonstrated that LR mainly removed ammonium(NH_4~+) from the water with a mean efficiency of 0.141 mg/(kg·h), while the removal of nitrate(NO_3~–) was not significant. Bacterial diversity analysis showed that ammonia-oxidizing bacteria(AOB) were the most common bacteria on LR, which accounted for 0.5%–1.4% of the total bacterial population, followed by denitrifying bacteria, which accounted for 0.2% of the total population, and the ammonia-oxidizing archaea(AOA) were the least common type(0.01%). The low abundance of denitrifying bacteria may be responsible for the poor nitrate(NO_3~–) removal of LR. Thus, other biological filtration methods are needed in coral aquaria to control nitrates generated from nitrification or biological metabolism.  相似文献   

18.
The influence of macronitrogen (NO - 3 and NH + 4 ) addition with Ulva pertusa on dissolved inorganic carbon system in seawater was studied. The results indicate that p(CO 2 ) and HCO 3 concentration decrease significantly, while pH and CO 2- 3 concentration increase significantly. When the concentration of NO 3 was less than 71 μmol/dm 3 or NH + 4 was less than 49.7 μmol/dm 3 , dissolved inorganic carbon (DIC) absorption rates by Ulva pertusa generally increased with the increasing of nitrogen concentration. The DIC decreased 151 μmol/dm 3 with the addition of 71 μmol/dm 3 NO 3 and decreased 232 μmol/dm 3 with the addition of 49.7 μmol/dm 3 NH + 4 after the experiment compared with DIC measured without nitrogen addition. A significant negative-correlation was found between c(DIC) and growth rate (μ) of Ulva pertusa (r = -0.91, P <0.000 1, n=11). NH + 4 had more influence on the species of inorganic carbon system than NO 3 .  相似文献   

19.
The importance of the nitrogen source for phytoplankton growth in a highly eutrophic embayment, Dokai Bay, was investigated. The DIN concentration often exceeded 100 μM of which 40–70% was NH4 +. During two incubation experiments, the natural assemblage of mainly diatoms took up NH4 + instead of NO3 −. The growth of two Skeletonema species isolated in Dokai Bay were significantly faster on NH4 + (1.86 and 1.27 div. d−1 respectively) than on NO3 − (1.55 and 1.04 div. d−1 respectively). Our results indicated that these diatoms could grow faster by using NH4 + compared to NO3 − in this eutrophic bay.  相似文献   

20.
为探讨海马齿(Sesuvium portulacastrum)对水域环境修复作用,本文研究了水培海马齿对不同盐度水质的碳汇作用以及不同形态氮的利用情况。实验设计0、10、20、30、35盐度梯度,海马齿水培时间82 d,然后测定植株干重、营养元素含量以及积累速率,最后在抑菌与不抑菌条件下研究海马齿根际与铵态氮(NH4+-N)、硝态氮(NO3--N)、无机磷(PO43-)以及色氨酸(Trp)吸收转化关系。研究结果表明,盐度10条件下海马齿植株干重、有机元素含量以及积累速率最高,有机碳、有机氮与有机磷积累速率分别为(5.572±1.611)、(0.313±0.058)、(0.057±0.013)mg/(d·ind.),而高盐环境35盐度条件下对海马齿生长造成一定胁迫。盐度0～35范围,海马齿均未出现死亡现象。不同盐度抑菌培养条件下,色氨酸与无机氮共存时均能被能被海马齿利用,色氨酸利用量远高于硝态氮、铵态氮;不抑菌条件下铵态氮则表现出增加的结果。海马齿作用在盐度...  相似文献   

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