Assessing ozone-precursor relationships based on a smog production model and ambient data

A semi-empirical model, Johnson's smog production model (SPM), which relates precursor emissions to ozone levels and estimates the relative effectiveness of volatile organic compounds (VOC) and NOx emission controls, has been evaluated and a modified version of SPM has been introduced. Both versions have been applied to routine data from 1989-1991 in five areas in the United States. In particular, extent parameters, which reveal the relative merit of VOC and NOx controls in reducing high ozone levels, have been calculated. Preliminary applications of SPM reveal interesting features with respect to VOC vs. NOx controls in reducing high ozone levels. For hourly data with ozone > or =0.08 ppm, distributions of extent parameters resulting from the modified SPM show the effectiveness of VOC controls at more monitoring sites than those from Johnson's SPM; however, relative features between the two versions are similar. On the other hand, for hourly data with ozone > or =0.12 ppm, the two SPM versions show very similar relative effectiveness of VOC and NOx controls with chosen values of model parameters. To improve the credibility of SPM, the range of validity of relationships between maximum smog produced or maximum ozone and NOx concentrations must be determined, and the parameters in these relationships must be better determined for typical VOC mixtures. Another essential parameter, which determines the fractional loss of NOy (NO and its oxidation products) from the gas phase must be better determined.     

An operational assessment of the application of the relative reduction factors in the demonstration of attainment of the 8-hr ozone National Ambient Air Quality Standard

The U.S. Environmental Protection Agency in 1997 revised the 1-hr ozone (O3) National Ambient Air Quality Standard (NAAQS) to one based on an 8-hr average, resulting in potential nonattainment status for substantial portions of the eastern United States. The regulatory process provides for the development of a state implementation plan that includes a demonstration that the projected future O3 concentrations will be at or below the NAAQS based on photochemical modeling and analytical techniques. In this study, four photochemical modeling systems, based on two photochemical models, Community Model for Air Quality and the Comprehensive Air Quality Model with extensions, and two emissions processing models, Sparse Matrix Optimization Kernel for Emissions and Emissions Modeling System, were applied to the eastern United States, with emphasis on the northeastern Ozone Transport Region in terms of their response to oxides of nitrogen and volatile organic carbon-focused controls on the estimated design values. With the 8-hr O3 NAAQS set as a bright-line test, it was found that a given area could be termed as being in or out of attainment of the NAAQS depending upon the modeling system. This suggests the need to provide an estimate of model-to-model uncertainty in the relative reduction factor (RRF) for a better understanding of the uncertainty in projecting the status of an area's attainment. Results indicate that the model-to-model differences considered in this study introduce     

Rapid reductive destruction of hazardous organic compounds by nanoscale Fe0

Fe0-mediated reductive destruction of hazardous organic compounds such as chlorinated organic compounds (COCs) and nitroaromatic compounds (NACs) in the aqueous phase is one of the latest innovative technologies. In this paper, rapid reductive degradation of COCs and NACs by synthesized nanoscale Fe0 in anaerobic batch systems was presented. The nanoscale Fe0, characterized by high specific surface area and high reactivity, rapidly transformed trichloroethylene (TCE), chloroform (CF), nitrobenzene (NB), nitrotoluene (NT), dinitrobenzene (DNB) and dinitrotoluene (DNT) under ambient conditions, which results in complete disappearance of the parent compounds from the aqueous phase within a few minutes. GC analysis reported that the main products of the dechlorination of TCE and CF were ethane and methane as well as that most of the nitro groups in NACs were reductively transformed to amine groups. These results suggest that the rapid reductive destruction by nanoscale Fe0 is potentially a viable in situ or aboveground treatment of groundwater contaminated with hazardous organic compounds including COCs and NACs.     

Performance of different microalgal species in removing nickel and zinc from industrial wastewater

A series of batch experiments was conducted to compare the ability of 11 microalgal species of the same cell density in removing nickel (Ni) and zinc (Zn) from synthetic wastewater. These included Chlorella vulgaris (commercially available), Chlorella sorokiniana and Scenedesmus quadricauda (isolates from polluted water of Wuhan, China), and eight different isolates from Hong Kong. The Wuhan isolate of Scenedesmus removed most Ni, probably due to its large biomass. Nickel concentration was reduced from an initial 30 to 0.9 mg/l after 5 min (97% Ni removal), and further declined to 0.4 mg/l after 90 min of treatment. In wastewater containing 30 mg/l Ni and 30 mg/l Zn, more than 98%, Ni and Zn were removed simultaneously at the end of 5 min treatment, indicating that the presence of Zn in wastewater did not affect Ni removal by this Scenedesmus isolate. The second most effective species for Ni removal was an isolate, tentatively identified as Chlorella miniata, Ni concentration was reduced to 10 mg/l after 90 min, and was only slightly interfered by the presence of Zn. In terms of metal removal per unit biomass or unit surface area of algal cells, C. miniata was the best species in removing Ni and Zn. At the other extreme, one Hong Kong isolate (Synechocystis sp.) did not remove any Ni and only achieved 40% Zn removal. Performance of the other isolates was comparable with the commercial C. vulgaris, less than 50% Ni was removed after 5 h of treatment and Ni removal was significantly reduced by the presence of Zn. All algae tested were found to be viable, showing these 11 species could tolerate a mixture of 30 mg/l Ni and 30 mg/l Zn in wastewater.     

Heavy metal concentrations in green-lipped mussels collected from Tolo Harbour and markets in Hong Kong and Shenzhen

Green-lipped mussels, Perna viridis, were collected from Kat O, Yim Tin Tsai, Ma Liu Shui and Tap Mun around Tolo Harbour and six local markets in Hong Kong (Aberdeen, Shau Kei Wan, Kowloon City, Mongkok, Yuen Long) and Shenzhen (Dongmun) between July 1994 and February 1995 and analysed for cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn). The metal concentrations of mussels collected from the study sites were Cd (0.45-1.44 microg/g), Cr (0.82-4.89 microg/g), Cu (6.02-23.99 microg/g), Ni (3.25-6.87 microg/g), Pb (2.02-4.36 microg/g) and Zn (90-135 microg/g), while those from the markets were Cd (0.27-1.44 microg/g), Cr (1.09-3.30 microg/g), Cu (9.05-17.8 microg/g), Ni (2.44-5.25 microg/g), Pb (1.17-5 microg/g) and Zn (51-103 microg/g). The metal concentrations were below the maximum permissible levels set by the Hong Kong Government. In addition, seasonal variation of metal accumulation in mussels was investigated in Yim Tin Tsai and Ma Liu Shui and a reduction in the total heavy metal concentrations during winter was noted. The non-carcinogenic hazard index of mussels collected from Tolo Harbour and from Hong Kong markets was between 0.46 and 1.36 compared with those from Shenzhen markets (0.85-1.46), which indicated a low but possible risk in consuming the mussels.     

Zinc-copper interaction affecting plant growth on a metal-contaminated soil

In order to assess the effects of metal interactions on plant growth, a greenhouse experiment was conducted, in which spring barley was grown for 48 days in a soil to which cadmium, copper, lead and zinc were added singly and in combination. Plant growth was measured as shoot and root dry matter production. At the end of the experiment the plant material was analysed for metal uptake and the soil was extracted with CaCl(2) solution, to measure the plant-available metal content. The most consistent effect on plant growth was an interaction between copper and zinc, which was also important in determining uptake of these metals and the amounts extractable with CaCl(2) solution. An analysis of the underlying mechanism led to the conclusion that the growth of barley was controlled principally by the amount of plant-available zinc, which depended on the amounts of both added zinc and added copper. The effect of the added copper was to increase the toxicity of the added zinc.     

Elevated levels of lead and other metals in roadside soil and grass and their use to monitor aerial metal depositions in Hong Kong

The Pb, Cu, Zn, Fe, Mn and Cd contents in roadside soils and grass from 36 sites on the Island of Hong Kong were determined by atomic absorption spectrometry. Results showed that both soil and grass contained elevated levels of the metals studied. Linear regression analysis between the logarithmic concentration of the metals in the samples and the logarithmic traffic volume of the sites revealed that, apart from Cd in soil, the two were strongly related (variance ratios' P values <0.001), thus indicating that the motor vehicle forms a major source of these metals in the roadside. The regional distribution of Pb and Cu in roadside soil and grass (presented in maps herein) shows high levels of contamination occurring mainly in the highly urbanised northern part of the Island where most of the traffic is concentrated. Apparently, both soil and grass could be utilised to reflect the extent of aerial deposition of metals in the roadside.     

Fine structure of naive and allogeneic challenged ampullae in Botrylloides subpopulation I from the Mediterranean coast of Israel

The external peripheral termini of vasculature in botryllid ascidians (ampullae) are important in the expression of effector mechanisms during histocompatibility reactions. We study here morphological changes to the microstructure during allorecognition in Botrylloides subpopulation I (SP1) from the Mediterranean coast of Israel, where special giant ampullae, called megaloampullae are developed hours after first allogeneic challenge. The basal part of each naive ampulla consists of a sheath of continuous squamous epithelial cells (1 μm×20 μm). At the tip of the ampullae, about 130 epithelial cells become columnar with wide apical pads (15 μm×5–10 μm), that contain electron-opaque “adhesive vesicles”. Foci of crystallizations were observed within the vesicles of some columnar cells. Ampullar epithelial cells develop internal folds that support tight attachments between circulating blood cells (most of them are pigment cells) and ampullar epithelium. During the histoincompatibility process, the tunic peripheral edge at the interaction area becomes highly convoluted. Filaments (up to 1.16 μm) accumulate in the interaction tunic matrix. Some of these filaments encircle destructed cells. Fragmented cell membranes are also found next to the reacting ampullae. The most characteristic feature of the Botrylloides SP1 rejection reaction is dilation of the ampullae. The ampullar epithelium becomes “curly” when megaloampullae are formed. Within the curly region, about 30% of the squamous epithelial cells are further stretched, up to 33 μm in length. Some additional mechanisms are suggested to explain the fast increase (up to seven times) in ampullar width that is recorded within a few hours from the first allogeneic contact.     

Photosynthetic characteristics of marine Synechococcus spp. with special reference to light environments near the bottom of the euphotic zone of the open ocean

The present study aimed to resolve the question why marine Synechococcus spp. abundantly occur even at the bottom of the euphotic zone in the Kuroshio are. Photosynthesis under such conditions was examined using simulated blue-green model light (BGL). Results indicated that photosynthesis of marine Synechococcus spp. under BGL is as active enough to support growth of these organisms. Examination of light-harvesting under BGL indicated that active photosynthesis is permitted by an unusually high abundance of phycoerythrin (PE), which is the main light-harvesting pigment for photosystem II (PSII), due to a phycobilisome (PBS) structure which is different from ordinary hemidiscoidals. Although the absorption maximum of PE is located at longer wavelengths than the energy maximum of BGL, PE was found to absorb BGL significantly. Thus, BGL cannot be a typical photosystem I (PSI) light. PSII is also significantly excited by BGL. Carotenoids, which largely absorb BGL, were found to be effective in light-harvesting for PSI. Based on the results obtained, possible reasons why marine Synechococcus spp. commonly occur in warm waters were discussed. Two strains of Synechococcus spp. isolated from the Gulf Stream in 1981 and from Kuroshio, Japan in 1983 were used in the present study.     

Remigration and growth of loggerhead turtles (<Emphasis Type="Italic">Caretta caretta</Emphasis>) nesting on Senri Beach in Minabe,Japan: life-history polymorphism in a sea turtle population

There are size-related differences in the use of feeding habitats (planktonic or benthic; oceanic or neritic) by adult female loggerhead sea turtles (Caretta caretta) within Japanese populations. We thus hypothesized that the differences may be reflected in their remigration and growth patterns, and investigated the relationships between body size and remigration intervals, growth rates, and remigration percentages, for female loggerheads nesting on a Japanese beach between 1991 and 2001. Although remigration intervals, growth rates, and remigration percentages were not significantly different among females, there were trends for longer remigration intervals and lower remigration percentages in smaller females. All females grew little. Considering these results along with previous findings, we speculated on the life-history strategy of female Japanese loggerheads.Communicated by T. Ikeda, Hakodate