Development of an Analytical Method for Nitric Oxide Radical Determination in Natural Waters

The measurement of photochemically generated nitric oxide radicals (NO) in natural waters has long been an arduous task because of a lack of simple analytical techniques, even though the environmental significance of this radical is paramount. We have developed a simple analytical method for the determination of photochemically generated NO in natural waters using 4,5-diaminofluorescein (DAF-2) as a probe compound. This method is based on the reaction of photoformed NO with DAF-2 in air-saturated solution to produce a highly fluorescent triazolofluorescein (DAF-2T) product. DAF-2T was determined by using reversed-phase HPLC with fluorescence detection, with excitation and emission wavelengths of 495 and 515 nm, respectively. Under optimum conditions, the calibration curve exhibited linearity in the range of 0.025−10 nM DAF-2T. The coefficients of variance for the measurements of the signal intensities of DAF-2T (from the photolysis of 0.5 μM and 5 μM NO2− with DAF-2) were less than 5% and 3%, respectively. For a total irradiation time of 30 min, the detection limit of the photoformation rate of NO was 1.65 × 10−13 M s−1, defined as 3σ of the lowest measured DAF-2T concentration (0.025 nM). The proposed method is relatively unaffected by potential interferents in seawater. The method was employed to determine the photoformation rate of NO in the Seto Inland Sea and the Kurose River in Hiroshima Prefecture, Japan. The measured NO photoformation rates in seawater and river water samples ranged from (5.3−32) × 10−12 M s−1 and (9.4−300) × 10−12 M s−1, respectively

Photochemical Production and Consumption Mechanisms of Nitric Oxide in Seawater

Nitric oxide (NO•) is an active odd-nitrogen species that plays a critical role in determining the levels of ozone (O3) and other nitrogen species in the troposphere. Here, we provide experimental evidence for photochemical formation of NO• in seawater. Photoproduction rates and overall scavenging rate constants were measured by irradiation of surface seawater samples collected from the Seto Inland Sea, Japan. Photoproduction rates of NO• ranged from 8.7 × 10−12 M s−1 to 38.8 × 10−12 M s−1 and scavenging rate constants were 0.05−0.33 s−1. The steady state concentrations of NO• in seawater, which were calculated from the photoproduction rates and scavenging rate constants were in the range 2.4−32 × 10−11 M. Estimation from the scavenging rate constant showed that the NO• lifetime in seawater was a few seconds. Our results indicate that nitrite photolysis plays a crucial role in the formation of NO•, even though we cannot exclude minor contributions from other sources. Analysis of filtered and unfiltered seawater samples showed no significant difference in NO• photoformation rates, which suggests a negligible contribution of NO• produced by photobiological processes. Using an estimated value of the Henry’s law constant (kH ≈ 0.0019 M atm−1), a supersaturation of surface seawater of 2 to 3 orders of magnitude was estimated. On the basis of the average values of the surface seawater concentration and the atmospheric NO• concentration, a sea-to-air NO• flux was estimated

Concentrations of organic acids in automobile and incinerator exhaust gases and their emission rates into the atmosphere

大気中有機酸の発生源である自動車および焼却炉排ガスについて，有機酸（ギ酸，酢酸，プロピオン酸，シュウ酸）濃度を測定した。ガソリン車の排ガス中有機酸濃度の相加平均値は，ギ酸59.7ppbv，酢酸327ppbv，プロピオン酸12.1ppbv，シュウ酸0.77ppbv（parts per billion by volume）であった。ディーゼル車および二輪車は，ガソリン車よりも有機酸濃度がやや高く，特に二輪車の酢酸は10ppmv（parts per million by volume）以上と高かった。広島大学東広島キャンパス設置の焼却炉排ガス中有機酸の組成および濃度は，ガソリン車と同様だった。自動車有機酸の組成及び濃度は，排気量，走行距離とは特に相関が見られず，これらは主に燃料組成，エンジン機構および排ガス浄化装置により決定すると考えられた。排ガス中有機酸の濃度比を，東広島における降水，露，大気中有機酸のそれと比較すると，降水よりも露および大気中有機酸の濃度比に近いことが示された。測定結果から，日本国内の自動車起源の有機酸年間発生量は，ギ酸3.0×109g yr-1，酢酸5.3×109g yr-1，プロピオン酸4.6×108g yr-1，シュウ酸7.9×107g yr-1と見積もられた。さらに一酸化炭素を指標として大気中有機酸への自動車起源有機酸の寄与を計算すると，ギ酸41％，酢酸18％となった。The concentrations of organic acids (formic, acetic, propionic and oxalic acids) were measured in automobile and incinerator exhaust gases, which are one of major sources of atmospheric organic acids. The mean concentrations of formic, acetic, propionic and oxalic acids in the exhaust gases of gasoline-powered vehicles (seven automobile models) were 59.7, 327, 12.1 and 0.77ppbv (parts per billion by volume), respectively. The organic acid concentrations in exhaust gases from one diesel-powered automobile model and two motorcycle models were higher than those from the gasoline-powered vehicles. The acetic acid concentrations in the exhaust gases from the motorcycles were particularly high at >10ppmv (parts per million by volume). The type of fuel, engine, and purification system of the exhaust gas probably determine the concentrations of organic acids in the exhaust gas. The concentrations of organic acids in exhaust gas from an incinerator at the Higashi-Hiroshima campus of Hiroshima University (Japan) were similar to those in the exhaust gas from gasoline-powered vehicles. The concentration ratios of formic, acetic and oxalic acids in automobile exhaust gas were compared with those of atmospheric organic acids, precipitation, and dew. The organic acid concentration ratios in automobile exhaust gas were more similar to those in dew and the atmosphere than those in precipitation. Based on the organic acid concentrations in the automobile exhaust gases, the annual emission rates from all automobiles in Japan were estimated to 3.0×109, 5.3×109, 4.6×108 and 7.9×107g yr-1 for formic, acetic, propionic and oxalic acids, respectively, The percentage contributions of formic and acetic acids from automobile exhaust gas to the acid concentrations in the atmosphere were estimated to 41% and 18%, respectively, using carbon monoxide as an indicator of automobile exhaust gas.本研究は，科学技術振興事業団（JST，現科学技術振興機構），戦略的基礎研究推進事業（CREST），環境低負荷型の社会システムより支援を受けて行われた。また文部科学省科学研究費補助金（研究課題番号14380244）および日産科学振興財団からも助成を受けたものである

Application of Fenton reaction for nanomolar determination of hydrogen peroxide in seawater

A simple and sensitive method for the determination of nanomolar levels of hydrogen peroxide (H2O2) in seawater has been developed and validated. This method is based on the reduction of H2O2 by ferrous iron in acid solution to yield hydroxyl radical (•OH) which reacts with benzene to produce phenol. Phenol is separated from the reaction mixture by reversed phase high performance liquid chromatography and its fluorescence intensity signals were measured at excitation and emission of 270 and 298 nm, respectively. Under optimum conditions, the calibration curve exhibited linearity in the range of (0–50) × 103 nmol L−1 H2O2. The relative standard deviations for five replicate measurements of 500 and 50 nmol L−1 H2O2 are 1.9 and 2.4%, respectively. The detection limit for H2O2, defined as three times the standard deviation of the lowest standard solution (5 nmol L−1 H2O2) in seawater is 4 nmol L−1. Interference of nitrite ion (NO2−) on the fluorescence intensity of phenol was also investigated. The result indicated that the addition of 10mol L−1 NO2− to seawater samples showed no significant interference, although, the addition of 50mol L−1 NO2 − to the seawater samples decreases the fluorescence intensity signals of phenol by almost 40%. Intercomparison of this method with well-accepted (p-hydroxyphenyl) acetic acid (POHPAA)-FIA method shows excellent agreement. The proposed method has been applied on-board analysis of H2O2 in Seto Inland seawater samples

Hepatitis B virus genotype assignment using restriction fragment length polymorphism patterns

AbstractHepatitis B virus (HBV) is classified into genotypes A–F, which is important for clinical and etiological investigations. To establish a simple genotyping method, 68 full-genomic sequences and 106 S gene sequences were analyzed by the molecular evolutionary method. HBV genotyping with the S gene sequence is consistent with genetic analysis using the full-genomic sequence. After alignment of the S sequences, genotype specific regions are identified and digested by the restriction enzymes, HphI, NciI, AlwI, EarI, and NlaIV. This HBV genotyping system using restriction fragment length polymorphism (RFLP) was confirmed to be correct when the PCR products of the S gene in 23 isolates collected from various countries were digested with this method. A restriction site for EarI in genotype B was absent in spite of its presence in all the other genotypes and genotype C has no restriction site for AlwI. Only genotype E is digested with NciI, while only genotype F has a restriction site for HphI. Genotype A can be distinguished by a single restriction enzyme site for NlaIV, while genotype D digestion with this enzyme results in two products that migrates at 265 and 186 bp. This simple and accurate HBV genotyping system using RFLP is considered to be useful for research on HBV

Behavior and Sources of Atmospheric Ozone, Nitrogen Oxides and Sulfur Dioxide in Yakushima, Japan

The concentration of ozone (O3), nitrogen oxides (NOx) and sulfur dioxide (SO2) in the atmosphere of Yakushima, a remote island of southern Japan, was measured in 2000-2001. Average concentrations of O3 were 29 and 43 ppbv at Seibu-Rindo (western area of Yakushima) and at Anbo (eastern area), respectively, in October 2000 and 49 and 46 ppbv at these areas, respectively, in February 2001 while average NOx concentrations were 2.2 and 2.8 ppbv at Seibu-Rindo and at Anbo, respectively, in October 2000 and 2.6 and 2.1 ppbv at these areas, respectively, in February 2001. No significant diurnal variation of O3 and NOx concentrations were found in both areas. Average concentrations of SO2 were 0.7 and 0.2 ppbv at Seibu-Rindo in October 2000 and at Anbo in February 2001, respectively, while a large increase of SO2 concentration (up to 11.0 and 12.5 ppbv) was recorded at Anbo in October 2000 and at Seibu-Rindo in February 2001, respectively, when air mass was derived from Kyushu Island by passing over Mt. Sakurajima (a volcano) in October 2000 and air mass coming from the Asian Continent / the Japan Islands in February 2001. THe data of air pollutant concentrations in Miyanoura (northern area of Yakushima), irregularly monitored by Kagoshima prefecture office, conbined with meteorological data in Kagoshima prefecture, suggested that O3 concentration would be higher (up to 60 ppbv) during fall to spring due to predominant northwest winds originating from the Asian Continent / the Japan Islands while, in other seasons, O3 concentrations would be lower due to predominant south winds originating from Pacific Ocean. Higher O3 concentrations during cold seasons could cause forest decline phenomena in Yakushima. SO2 were suggested to be transported from Mt. Sakurajima and from the region of the Asian Continent / the Japan Islands and its effect to forest plants needs to be evaluated by further monitoring

Distribution of dioxins in atmospheric deposition, soils, and bottom sediments of rivers and coastal sea in Hiroshima prefecture, Japan

Distribution of dioxins (PCDDs, PCDFs, and Co-PCBs) in atmospheric deposition, soils, and bottom sediments of rivers and coastal sea were examined in Hiroshima prefecture, Japan during 1998-1999. The monthly concentrations of PCDDs/DFs in atmospheric deposition (rain and dry deposition together) were 1.3-3.3 pg-TEQ/L and the monthly depositions were 4.1-20 pg TEQ/m2/day in Fukuyama during April to September in 1999. PCDDs/DFs concentrationsin soils were 4.9-34,1.2-2.5, 1.1-6700 and 77-86 pg-TEQ/dry g at Mt. Gokurakuji in Hatsukaichi, at a forest in Souryou Town, at industrial incinerators in Fukuyama and at paddy fields in Higashi-Hiroshima, respectively. Very high concentrations found in the soils at the industrial incinerator suggest the contamination of ashes into the soils due to uncontrolled burning in open fire and relatively higher concentrations in the paddy fields indicate the successive utilization of pesticides in the past years. Dioxins in the bottom sediments collected from Ohta River in Hiroshima City were ranged to be 1.4-6.1 pg-TEQ/dry g.PCDDs/DFs concentrations in the Seto Inland Sea bottom sediments were 0.6 to 14 pg-TEQ/dry g and their concentrations were higher in Hiroshima Bay than those at off coast, suggesting that dioxins brought by Ohta River and other rivers are accumulated in the Bay sediments. Maximum concentration of PCDDs/DFs was found in the core sediments deposited in 1970s-1980s, suggesting large production of dioxins by human activities in these decades

Applicability of solar photo-Fenton process to the remediation of water polluted with pesticides

Staff PublicationThe applicability of solar photo-Fenton process to the degradation of three pesticides in pure and natural waters was investigated in Fe(III)/H2O2/UV–Vis and Fe(III)/H2O2 UV–Vis oxidation systems at pH 2.8 and 7.2. The pesticides concentrations were determined by HPLC analysis. Furthermore, total mineralization of the pesticides in these systems was evaluated by monitoring the decreases in DOC concentrations with solar simulator irradiation time by TOC analysis. The results obtained indicate that the spontaneous degradation due to solar illumination by Fe3+/H2O2/UV–Vis system is more effective than Fe2+/ H2O2/UV–Vis system in Milli-Q water and river water at pH 2.8. This great enhancement in the pesticides degradation rate in the photo-Fenton reaction system Fe3+/H2O2/UV– Vis compared to Fe2+/H2O2/UV–Vis systems at pH 2.8 is due to the higher rate of ·OH generation in this system in Milli-Q water and river water (4.01 and 5.26 uM/min) compared to Fe2+/H2O2/UV–Vis systems 2.44 and 2.90 uM/min. respectively. At both pH values, the order of pesticides degradation was diuron > fenitrothion > fenarimol which seems to be related with their solubility. Results obtained from this study makes it plausible to apply the photo-Fenton process to the remediation of water polluted with toxic pesticide

Epidemiological Study of Lipoprotein (a) in Okinawa

A study of serum levels of lipoprotein (a) (Lp (a)) was performed among 217 normal adults including 135 men and 82 women in the northern part of Okinawa. Ages of the subjects ranged from 24 to 76 with an average of 49 years. Concentrations of Lp (a) in blood were measured by sandwich ELISA. The average Lp (a) concentration was 20.7 mg/ dl and the peak of the distribution of serum Lp (a) concentration ranged from 10 to 15 mg/dl. A greater number of people in the investigated area tended to show a higher level of serum concentration of Lp (a) than those in any other prefectures in Japan, although there was no significant relationship between serum level of lipoprotein (a), total cholesterol, triglyceride, age or gender in healthy subjects

Reviews and Syntheses: Ocean acidification and its potential impacts on marine ecosystems

Ocean acidification, a complex phenomenon that lowers seawater pH, is the net outcome of several contributions. They include the dissolution of increasing atmospheric CO₂ that adds up with dissolved inorganic carbon (dissolved CO₂, H₂CO₃, HCO₃⁻, and CO₃²⁻) generated upon mineralization of primary producers (PP) and dissolved organic matter (DOM). The aquatic processes leading to inorganic carbon are substantially affected by increased DOM and nutrients via terrestrial runoff, acidic rainfall, increased PP and algal blooms, nitrification, denitrification, sulfate reduction, global warming (GW), and by atmospheric CO₂ itself through enhanced photosynthesis. They are consecutively associated with enhanced ocean acidification, hypoxia in acidified deeper seawater, pathogens, algal toxins, oxidative stress by reactive oxygen species, and thermal stress caused by longer stratification periods as an effect of GW. We discuss the mechanistic insights into the aforementioned processes and pH changes, with particular focus on processes taking place with different timescales (including the diurnal one) in surface and subsurface seawater. This review also discusses these collective influences to assess their potential detrimental effects to marine organisms, and of ecosystem processes and services. Our review of the effects operating in synergy with ocean acidification will provide a broad insight into the potential impact of acidification itself on biological processes. The foreseen danger to marine organisms by acidification is in fact expected to be amplified by several concurrent and interacting phenomena