Levels of black carbon and their relationship with particle number levels—observation at an urban roadside in Taipei City

Information on the relationship between black carbon (BC) and particle number levels in urban areas is limited. Therefore, investigating the relationship between BC and particle number levels in different particle size ranges at an urban area is worthwhile. This study used an aethalometer and scanning mobility particle sizer to measure the levels of BC and particle number simultaneously at an urban roadside in Taipei City. Measurement results show that hourly BC levels are 0.62–8.80 μg m^?3 (mean?=?3.50 μg m^?3) and hourly particle number levels are 4.21?×?10³–4.64?×?10⁴ particles cm^?3 (mean?=?2.00?×?10⁴ particles cm^?3) in Taipei urban area. The BC and particle number levels peak during morning (7:00–9:00) and evening (16:00–18:00) rush hours on weekdays. Low BC and particle number levels exist in the early morning hours. Time variations in BC levels are the same as those of particle number levels in this study, clearly indicating that BC and particles are likely released from the same emission source. Additionally, BC levels in the urban area are more strongly associated with ultrafine particle levels than with total particle number levels, particularly in the size range of 56–180 nm. According to measurement results, most BC in aerosols in urban areas can be in the ultrafine size range.     

Monitoring and assessing variation of sewage quality and microbial functional groups in a trunk sewer line

In this study, the variation of sewage quality was investigated and the active fraction of different microbial functional groups in biofilm was quantified in a 5.6-km trunk sewer line. The sewage quality including suspended solids, biochemical oxygen demand, total chemical oxygen demand (COD), total nitrogen, total Kjeldahl nitrogen, ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen were measured and compared with the values in literatures. The results indicated that since the wastewater treatment plant was not operated at its full capacity, the concentrations of different compounds were lower compared with the values in literatures. The values of heterotrophic growth rate constant lay between 5.6 and 8.6 day^???1. Its average value was 7.7 day^???1. The values of heterotrophic lysis rate constant lay between 0.2 and 0.4 day^???1. The active heterotrophic biomass in biofilm varied from 240 to 800 mg COD m^???2 and average value was 497 mg COD m^???2. The biofilm mass varied from 880 to 1,080 mg m^???2. The percentage of heterotroph to biofilm mass fall within the range of 24.0–90.9% and average value was 52.9%. In the oxygen uptake rate batch tests, the biomass, growth rate constant, and lysis rate constant of autotroph could not be determined because the fraction of autotroph in biofilm was relatively few. It revealed that the degradation of organic matters, nitrification, and denitrification occurred in the trunk sewer line. But the results indicate that the condition seem favorable for nitrification.     

Relationships between aqueous solubility and octanol-water partition coefficients

The physical chemical equations relating solubility to octanol water partition coefficient are presented and used to develop a new correlation between these quantities which includes a melting point (fugacity ratio) correction. The correlation is satisfactory for 45 organic compounds but it is not applicable to organic acids. When applied to very high molecular weight (> 290) compounds the correlation is less satisfactory; either it is believed because the data are inaccurate or because the tendency for these compounds to partition into organic phases is less than expected. This may have profound environmental implications.     

中国黑钻鳞耳蕨组（耳蕨属）的研究

对中国黑钻鳞耳蕨组（耳蕨属）种类进行了分类处理．确认中国有12种，并报导了其中2个新种：浪穹耳蕨（Polystichumlangchungense）、洪雅耳蕨（P．pseudo-xiphophyllum）．     

Biofiltration of trimethylamine-containing waste gas by entrapped mixed microbial cells

The study provides novel attempt to use an aerobic biofiltration system containing entrapped mixed microbial cells (EMMC) for removal of (CH3)3N-dominant waste gases. In the study, heterotrophic microflora-immobilized cellulose was packed into an EMMC reactor to degrade (CH3)3N. Effects of (CH3)3N inlet concentrations in continuous mode of operation at various flow rates are indicated. The result indicated that the (CH3)3N removal efficiency is higher than 90% at inlet loading below 27.2 mgNh(-1) and retention time 5.3 min. In addition, the maximal mass loading to reach approximately 99% efficiency was 95.5 mgNh(-1) for trimethylamine treatment. This EMMC biofiltration system also showed higher tolerance to endure fluctuations in concentrations and flow rates and still maintained in stable performance for removal. Adaptability test in response to gradual shift up and down of inlet TMA loading indicated that lack of steady-state multiplicity and hysteresis guarantees the microbial communities more precisely adapted to continuous treatment for maintaining stability.     

Air pollution “holiday effect” resulting from the Chinese New Year

Our study was an attempt to conduct a comprehensive and systematical examination of the holiday effect, defined as the difference in air pollutant concentrations between holiday and non-holiday periods. This holiday effect can be applied to other countries with similar national or cultural holidays. Hourly and daily surface measurements of six major air pollutants from thirteen air quality monitoring stations of the Taiwan Environmental Protection Administration during the Chinese New Year (CNY) and non-Chinese New Year (NCNY) periods were used. We documented evidence of a “holiday effect”, where air pollutant concentrations were significantly different between holidays (CNY) and non-holidays (NCNY), in the Taipei metropolitan area over the past thirteen years (1994–2006).The concentrations of NO_x, CO, NMHC, SO₂ and PM₁₀ were lower in the CNY than in the NCNY period, while the variation in the concentration of O₃ was reversed, which was mainly due to the NO titration effect. Similar differences in these six air pollutants between the CNY and NCNY periods were also found in the diurnal cycle and in the interannual variation. For the diurnal cycle, a common traffic-related double-peak variation was observed in the NCNY period, but not in the CNY period. Impacts of dust storms were also observed, especially on SO₂ and PM₁₀ in the CNY period. In the 13-year period of 1994–2006, decreasing trends of NO_x and CO in the NCNY period implied a possible reduction of local emissions. Increasing trends of SO₂ and PM₁₀ in the CNY period, on the other hand, indicated a possible enhancement of long-range transport. These two mechanisms weakened the holiday effect.     

Photochemical production of ozone and control strategy for Southern Taiwan

An observation-based method (OBM) is developed to evaluate the ozone (O₃) production efficiency (O₃ molecules produced per NO_x molecule consumed) and O₃ production rate (P(O₃)) during a field campaign in southern Taiwan. The method can also provide an estimate of the concentration of OH. A key step in the method is to use observed concentrations of two aromatic hydrocarbons, namely ethylbenzene and m,p-xylene, to estimate the degree of photochemical processing and amounts of photochemically consumed NO_x and NMHCs by OH. In addition, total oxidant (O₃+NO₂) instead of O₃ itself turns out to be very useful for representing ozone production in the OBM approach. The average O₃ production efficiency during the field campaign in Fall (2003) is found to be about 10.2±3.9. The relationship of P(O₃) with NO_x is examined and compared with a one-dimensional (1D) photochemical model. Values of P(O₃) derived from the OBM are slightly lower than those calculated in the 1D model. However, OH concentrations estimated by the OBM are about a factor of 2 lower than the 1D model. Fresh emissions, which affect the degree of photochemical processing appear to be a major cause of the underestimate. We have developed a three-dimensional (3D) OBM O₃ production diagram that resembles the EKMA ozone isopleth diagram to study the relationship of the total oxidant versus O₃ precursors. The 3D OBM O₃ production diagram suggests that reducing emissions of NMHCs are more effective in controlling O₃ than reducing NO_x. However, significant uncertainties remain in the OBM, and considerable more work is required to minimize these uncertainties before a definitive control strategy can be reached. The observation-based approach provides a good alternative to measuring peroxy radicals for evaluating the production of O₃ and formulating O₃ control strategy in urban and suburban environments.     

Mutagenic and carcinogenic potency of extracts of diesel and related environmental emissions: In vitro mutagenesis and oncogenic transformation

Extracts from emissions of four diesel engines, a gasoline engine and three related environmental samples were tested in four in vitro assay systems designed to detect carcinogenic or mutagenic activity of chemicals. Samples from three of four diesel extracts, the gasoline engine, and all three related samples were positive in an enhancement of viral transformation assay. Two diesel samples, the gasoline engine extract and extract from coke oven emissions were positive for mutation induction in Chinese hamster ovary cells. Only the gasoline engine extract and the coke oven sample were positive in a DNA fragmentation assay using alkaline sucrose gradients. Experiments using chemical transformation of Syrian hamster embryo cells as an assay method have not been completed.     

Effect of coplanar PCB concentration on dechlorinating microbial communities and dechlorination in estuarine sediments

The effect of concentration of coplanar PCB on the dechlorinating microbial community and dechlorination were investigated in anoxic estuarine sediment collected from Er-Jen River and enriched with 10 and 50 mg L⁻¹ of 3,4,4′,5-tetrachlorobiphenyl, 3,3′,4,4′,5-pentachlorobiphenyl, and 3,3′,4,4′,5,5′-hexachlorobipheny. Dechlorination rates were similar in the cultures enriched with 10 and 50 mg L⁻¹ of 3,4,4′,5-tetrachlorobiphenyl, whereas significantly higher dechlorination rates were observed in cultures enriched with 10 mg L⁻¹ of 3,3′,4,4′,5-pentachlorobiphenyl. No dechlorination was observed in sediment slurries enriched with 3,3′,4,4′,5,5′-hexachlorobipheny. Para dechlorination occurred prior to meta dechlorination during reductive dechlorination of 3,4,4′,5-tetrachlorobiphenyl and 3,3′,4,4′,5-pentachlorobiphenyl. GC-MS and denaturing gradient gel electrophoresis (DGGE) were used to detect dechlorination products and dechlorinating microorganisms in the enriched sediment cultures during the process of degradation. Two Chloroflexi phylotypes observed in DGGE were responsible for para and meta dechlorination respectively. Phylotype Cp-1 has 98% similarity to uncultured bacterium N5-12. Phylotype Cm-1 has 99% similarity to uncultured dechlorinating bacterium m1 or SF1 belonging to the ο-17/DF-1 group of PCB-dechlorinating bacteria.