Impacts of ship emissions and sea-land breeze on urban air quality using chemical characterization, source contribution and dispersion model simulation of PM2.5 at Asian seaport.

Fine particulate matter (PM2.5) emitted from marine transportation, bulk materials handling at the docks, and dust dispersion has garnered increased attention, particularly in the interface between port and urban areas. This study explored the inter-transport of PM2.5 between Kaohsiung Harbor and neighboring Metro Kaohsiung. Chemical analyses of PM2.5 samples from four sites include water-soluble ions, metallic elements, carbons, anhydrosugars, and organic acids to establish PM2.5's chemical fingerprints. The CALPUFF air dispersion model is employed to simulate the spatiotemporal distribution of PM2.5 in Kaohsiung Harbor and adjacent urban areas. A clear seasonal and diurnal variation of PM2.5 concentrations and chemical composition was observed in both harbor and urban areas. The high correlation of nighttime PM2.5 levels between the port and urban areas suggests inter-transport phenomena. Sea salt spray, ship emissions, secondary aerosols, and heavy fuel-oil boilers exhibit higher levels in the port area than in the urban area. In Metro Kaohsiung, mobile sources, fugitive dust, and waste incinerators emerge as major PM2.5 contributors. Furthermore, sea breeze significantly influences PM2.5 dispersion from Kaohsiung Harbor to Metro Kaohsiung, particularly in the afternoon. The average contribution of PM2.5 from ships' main engines in Kaohsiung Harbor ranges from 2.9% to 5.3%, while auxiliary engines contribute 3.8%-8.3% of PM2.5 in Metro Kaohsiung.

Identification of potential source regions and long-range transport routes/channels of marine PM2.5 at remote sites in East Asia.

Long-range transport (LRT) of air masses in East Asia and their impacts on marine PM2.5 were explored. Situated in the leeward region of East Asia, Taiwan Island marked by its elevated Central Mountain Range (CMR) separates air masses into two distinct air currents. This study aims to investigate the transport of PM2.5 from the north to the leeward region. Six transport routes (A-F) were identified and further classified them into three main channels (i.e. East, West, and South Channels) based on their transport routes and potential sources. Green Island (Site GR) and Hengchun Peninsula (Site HC) exhibited similarities in their transport routes, with Central China, North China, and Korean Peninsula being the major source regions of PM2.5, particularly during the Asian Northeastern Monsoons (ANMs). Dongsha Island (Site DS) was influenced by both Central China and coastal regions of East China, indicating Asian continental outflow (ACO) as the major source of PM2.5. The positive matrix factorization (PMF) analysis of PM2.5 resolved that soil dust, sea salts, biomass burning, ship emissions, and secondary aerosols were the major sources. Northerly Channels (i.e. East and West Channels) were primarily influenced by ship emissions and secondary aerosols, while South Channel was dominated by oceanic spray and soil dust. The results of W-PSCF and W-CWT analysis indicated that three remote sites experienced significant contributions from Central China in the highest PM2.5 concentration range (75-100%). In contrast, PM2.5 in the 0-25% and 25-50% ranges primarily originated from the open seas, with ship emissions being the prominent source. It suggested that northern regions with heavy industrialization and urbanization have impacts on high PM2.5 concentrations, while open seas are the main sources of low PM2.5 concentrations.

Spatiotemporal distribution characteristics and potential sources of VOCs at an industrial harbor city in southern Taiwan: Three-year VOCs monitoring data analysis.

Kaohsiung City is the largest harbor city in Taiwan. The Linhai Special Industrial Complex (LSIC), which is the largest heavy industrial zone in Taiwan, and other industrial zones and storage station of petrochemicals are adjacent to the Kaohsiung Port. Volatile organic compounds (VOCs), which are discharged from industrial processes in this large industrial area, are likely to cause the poor ambient air quality and atmospheric visibility in Kaohsiung City. This study uses the continuous monitoring data of 54 VOCs during 2018-2020 at eight air quality monitoring stations in the industrialized city to evaluate the spatiotemporal distributions and seasonal variations of VOC concentrations. Principal component analysis and ratios of benzene, toluene, ethylbenzene and xylenes (BTEX) are used to track the potential sources of VOCs for different stations. The highest average concentration of total volatile organic compounds (TVOC) was observed in winter (32.54 ppb), while the lowest TVOC concentration was observed in summer (25.84 ppb), which is related to the prevailing wind directions of monsoons. Kaohsiung is located in the weak monsoon wake area, and air pollutants are easily accumulated in the winter. The southwest wind prevailing in summer results in good diffusion and frequent rainfalls. However, the Qijin station close to the seashore has the highest average TVOC concentration among the eight stations. The seasonal prevailing winds caused the average TVOC concentrations in summer (41.3 ppb) to be higher than that in winter (31.62 ppb) at the Qijin station. It was attributed to the fact that the Qijin Peninsula is vulnerable to VOC emissions from ship sailing in the Taiwan Strait, the processing and export zone, and the shipbuilding yards nearby the Kaohsiung Harbor. Comparing the BTEX ratios of Kaohsiung City with the data of Hong Kong, we found that VOCs were mainly from industrial emissions in Kaohsiung City, which were significantly different from Hong Kong that VOCs were mainly emitted from traffic emissions. Overall, VOCs in Kaohsiung City have been decreased from 2018 to 2020; however, according to the analytical results of ozone formation potential, toluene and m,p-xylenes are the most potential photochemical precursors for ozone formation. The government should enforce and regulate aromatic hydrocarbons from industrial emission sources to reduce the potential formation of ozone.

Use of passive SPME sampling devices to determine exposure of oil painters to organic compounds.

A solid-phase microextraction (SPME) sampling device, called a needle trap samplers (NTS) that were packed with 60-80 mesh divinylbenzene (DVB) particles, was used to extract indoor volatile organic compounds (VOCs) that were emitted in an oil painting studio. This work compared the sampling performances of a passive NTS and an active charcoal desorption tube that was connected to a personal sampling pump (Method 1501), developed by the National Institute of Occupational Safety and Health, USA. The experimental results reveal that the NTS is a dependable alternative device to Method 1501 for monitoring indoor air quality. 2,2,4,6,6-Pentamethylheptane (isododecane) is the main emitted pollutant when oil painters use odorless thinner as a substitute solvent for turpentine oil, and the mean exposed concentrations of isododecane determined by NTS ranged from 0.83 to 3.10 ppm, which were dependent on whether the indoor ventilation was performed by the natural or mechanic mode. To maintain adequate air exchange rates in an oil painting studio, doors should be opened to increase air circulation, lowering the concentrations of isododecane to which painters are exposed.Implications: A needle trap sampler (NTS) was used to sample VOCs from oil painting in an indoor studio. Isododecane is the main emitted pollutant when painters use the odorless thinner. The NTS was evaluated to be a dependable alternative to Method 1501 for monitoring indoor air quality. To maintain adequate air exchange rates in a painting studio, doors should be opened to lower concentrations of VOCs.

Quantification of VOC emissions from paint spraying on a construction site using solid phase microextraction devices.

The objective of this study was to measure the emission of, and personal exposure to workers, volatile organic compound (VOC) during paint spraying on a construction site. Needle trap samplers (NTSs), which are a green solid phase microextraction sampling technology, were used to obtain air samples at a large music exhibition center. The standard active sampling method using charcoal tubes and a personal air pump, Method 1501, was simultaneously utilized at the sampling sites to assess the workers' VOC exposures. Analysis of the data thus obtained showed that benzene, toluene, ethylenebenzene, and xylenes (BTEXs) were the main emission compounds. Acetone and isobutyl alcohol, which are used as thinning solvents, were detected as minor emission compounds. The emitted concentrations of most compounds were lower than the legal emission limits in Taiwan except that of benzene, for which the 2-ppm time weighted average short-term exposure limit was exceeded. The packed divinylbenzene (DVB) in the NTS was observed under an environmental scanning electron microscope, and many fine aerosols were found to be deposited on the surface of the DVB adsorbents, causing VOC extraction efficiencies after the fifth sampling in the field to decline. Workers on construction sites should be protected from emissions of VOC and fine particulates to preserve their occupational health.

Preparation of needle trap samplers to extract air compounds from indoor electric-vaporizing sources.

UNLABELLED: In this study, gaseous benzene, toluene, ethylbenzene, and o-xylene (BTEX) were extracted by passive needle trap samplers (NTS) using divinylbenzene (DVB) particles (mesh sizes 60-80, 80-100, and 100-120, respectively) as packed sorbents. An aspirating pump measured sampling flow rates of NTS, and the relations between BTEX mass and sampling flow rates were sufficient to maintain the extraction performance of these self-designed DVB-NTS. Furthermore, this investigation compared the extraction efficiency of NTS with that of the 100-microm polydimethylsiloxane solid-phase microextration (PDMS SPME) fiber when applied to sample heating products from electric-vaporization anti-mosquito mats, and the experimental results indicated that NTS effectiveness increased with decreasing adsorbent particle diameter. Substantially less mass of gaseous BTEX was extracted using 100-microm PDMS SPME fiber than with NTS of 100-120 mesh DVB for 60-min TWA sampling of anti-mosquito mats. The 100-120 mesh DVB-NTS primarily adsorbed 4.2 ng acetone, 13.3 ng dichloromethane, and 4.5-25.3 ng C10-C12 alkanes. IMPLICATIONS: The needle trap sampler (NTS) has been evaluated to be a device for sampling heating products from electric-vaporization anti-mosquito mats. Based on the experimental results, this investigation assessed NTS as suitable for occupational and environmental health applications.

Breakthrough indicator for aromatic VOCs using needle trap samplers for activated carbon adsorbent.

Internal circulation cabinets equipped with granular activated carbon (GAC) for adsorbing volatile organic compounds (VOCs) are widely used to store bottles containing organic solvents in universities, colleges, and hospital laboratories throughout Taiwan. This work evaluates the VOC adsorption capacities of GAC using various adsorption times for gas stream mixtures of 100 ppm toluene and 100 ppm o-xylene. Additionally, needle trap sampling (NTS) technology was used to indicate the time for renewing the GAC to avoid VOC breakthrough from adsorbents. Experimental results demonstrate that the proposed models can linearly express toluene and o-xylene adsorption capacities as the natural logarithm of adsorption time (ln(t)) and can accurately simulate the equilibrium adsorption capacities (Qe, g VOCs/g GAC) for gaseous toluene and o-xylene. The NTS, packed with 60-80 mesh divinylbenzene (DVB) particles, was compared in terms of extraction efficiency by simultaneously using the 75-microm Carboxen/polydimethylsiloxane-solid-phase microextraction (Carboxen/PDMS-SPME) fiber for time-weighted average (TWA) sampling, and experimental results indicated that the packed DVB-NTS achieved higher toluene extraction rates. Additionally, the NTS installed in the outlet air stream for adsorbing toluene and o-xylene exhausted through GAC accurately indicated toluene and o-xylene breakthrough times of 4700-5000 min. The GAC-NTS operational instructions to indicate the replacing time of adsorbent in the internal circulation cabinets are also included in this paper.

Using a biological aerated filter to treat mixed water-borne volatile organic compounds and assessing its emissions.

A biological aerated filter (BAF) was evaluated as a fixed-biofilm process to remove water-borne volatile organic compounds (VOCs) from a multiple layer ceramic capacitor (MLCC) manufacturing plant in southern Taiwan. The components of VOC were identified to be toluene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, bromodichloromethane and isopropanol (IPA). The full-scale BAF was constructed of two separate reactors in series, respectively, using 10- and 15-cm diameter polypropylene balls as the packing materials and a successful preliminary bench-scale experiment was performed to feasibility. Experimental results show that the BAF removed over 90% chemical oxygen demand (COD) from the influent with (1188 +/- 605) mg/L of COD. A total organic loading of 2.76 kg biochemical oxygen demand (BOD)/(m3 packing x d) was determined for the packed bed, in which the flow pattern approached that of a mixed flow. A limited VOC concentration of (0.97 +/- 0.29) ppmv (as methane) was emitted from the BAF system. Moreover, the emission rate of VOC was calculated using the proposed formula, based on an air-water mass equilibrium relationship, and compared to the simulated results obtained using the Water 9 model. Both estimation approaches of calculation and model simulation revealed that 0.1% IPA (0.0031-0.0037 kg/d) were aerated into a gaseous phase, and 30% to 40% (0.006-0.008 kg/d) of the toluene were aerated.

Dissolved VOC concentrations and salt contents affecting air-sweat equilibrium partition of hydrophilic and hydrophobic VOCs.

Workers have frequently disregarded long-term dermal exposure to low concentration of gaseous volatile organic compounds (VOCs). To assess dermal exposure risk to gaseous VOCs, equilibrium partitioning coefficients (p(c)) at the air-sweat interface on human skin surface must be examined. This study analyzed the p(c) values of hydrophilic iso-propanol (IPA), methyl ethyl ketone (MEK), and hydrophobic benzene, toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene (BTEXs) at the air-water and air-sweat interfaces at 27-47 degrees C. The hydrophilic VOCs were dissolved in pure water and artificial human sweat liquors at approximately 10-125 mg/L, and hydrophobic VOCs were at approximately 0.55 mg/L. According to experimental results, the dissolved VOC concentration and salt contents simultaneously have a co-effect on p(c) during human dermal exposure to gaseous VOCs. The salt effect resulted in increase of p(c) for hydrophilic and hydrophobic VOCs, and the dissolved VOC concentration effect resulted in a reduction in p(c), which is dominant for hydrophilic compounds of high concentrations of aqueous VOCs. The p(c) data were utilized for further assessment of risk due to dermal exposure to VOCs.

Volatile organic compound emissions from wastewater treatment plants in Taiwan: legal regulations and costs of control.

This study assessed volatile organic compound (VOC) emission characteristics from wastewater treatment plants (WWTPs) in five Taiwanese industrial districts engaged in numerous manufacturing processes, including petrochemical, science-based industry (primarily semiconductors, photo-electronics, electronic products and biological technology), as well as multiple manufacturing processes (primarily pharmaceuticals and paint manufacturing). The most aqueous hydrocarbons dissolved in the wastewater of Taiwanese WWTPs were acetone, acrylonitrile, methylene chloride, and chloroform for the petrochemical districts; acetone, chloroform, and toluene for the science-based districts; and chlorinated and aromatic hydrocarbons for the multiple industrial districts. The aqueous pollutants in the united WWTPs were closely related to the characteristics of the manufacturing plants in the districts. To effectively prevent VOC emissions from the primary treatment section of petrochemical WWTPs, the updated regulations governing VOC emissions were issued by the Taiwanese Environmental Protection Administration in September 2005, legally mandating a seal cover system incorporating venting and air purification equipment. Cost analysis indicates that incinerators with regenerative heat recovery are optimal for treating high VOC concentrations, exceeding 10,000 ppm as CH(4), from the oil separation basins. However, the emission concentrations, ranging from 100 to 1,000 ppm as CH(4) from the other primary treatment facilities and bio-treatment stages, should be collected and then injected into the biological oxidation basins via existing or new blowers. The additional capital and operating costs required to treat the VOC emissions of 1,000 ppm as CH(4) from primary treatment facilities are less than USD 0.1 for per m(3) wastewater treatment capacity.

Air-water partitioning equilibrium of tetrahydrofuran in an activated sludge system.

This study evaluate the effect of liquid tetrahydrofuran (THF) concentration and biomass content on the THF air-water partitioning equilibrium for a simulated activated sludge system. The equilibrium of the partition at the air-water interface is given by a partitioning coefficient (pc) = Cg*/CL, where Cg* denotes the gaseous concentration in equilibrium with the aqueous THF concentration (CL). Variations of pc with CL in static pure water are evaluated, and high solubility of THF in water caused pc values to drop as the CL increased from 29.81 +/- 0.16 to 297.75 +/- 2.28 mg/L at a constant temperature of 27 degrees C. Meanwhile, the hydrophilicity of THF in water induced a biomass effect, causing pc to increase in the activated sludge liquor. Due to the co-effect of liquid THF concentration and biomass content, the pc values of THF for the liquor of mixed liquid suspended solid (MLSS) concentration = 1220 +/- 86 mg/L and THF CL = 242.91 +/- 69.09 mg/L increased 22.5% compared to those in the pure agitated water. The biomass effect on pc of hydrophilic VOC increases the gaseous VOC emission rate from the activated sludge facilities.

Simulating the emission rate of volatile organic compounds from a quiescent water surface: model development and feasibility evaluation.

Organic solvents are commonly used in industrial manufacturing processes, resulting in large quantities of volatile organic compounds (VOCs) emitted from effluent wastewater treatment facilities. This work presents a novel stainless steel simulator designed for developing a model that estimates VOC emission rates from a quiescent water surface in an open/unaerated basin. The target pollutants were aqueous VOCs: alcohols (ethanol and iso-propanol) and methyl ethyl ketone. Two aromatic hydrocarbons, toluene and benzene, were also used and each mixed with ethanol. A formula, based on penetration theory and the concept of mass balance, was devised for simulating emission rates (N), with the following variables: wind velocity (W) above the air-water interface with a power number of beta, the VOC concentration (Cg*) at equilibrium with aqueous concentration (CL), and the emitted concentration (Cg). Restated, N = kWbetaAS(Cg*-Cg), where k and beta denote dimensionless constants, which were solved herein, and As represents the emission surface area. From the proposed formula, three parameters (CL, water temperature, and W) were controlled during each simulation test to derive k and beta values. To assess the feasibility of the simulation procedures for real water with multiple VOC compositions, a large open neutralization basin was used to measure the VOC emission rate. Comparing the calculated results, respectively using the proposed formula and emission model Water 8 developed by the U.S. EPA in 1985, confirmed that the proposed simulation method was a feasible alternative to Water 8.

Determining the equilibrium partitioning coefficients of volatile organic compounds at an air-water interface.

The single equilibration technique (SET) was adopted to determine the partitioning coefficients (pc) at an air-water interface for volatile organic compounds (VOCs), including ethanol, iso-propanol (IPA), iso-butanol (IBA), methyl ethyl ketone (MEK) and toluene, all extensively used in industrial processes. Standard SET procedures were established. The liquid concentrations (CL) of tested VOCs ranged from 10 to 125 mg l(-1) for alcohols and MEK, and from 0.5 to 20 mg l(-1) for toluene. The temperatures (Tw) of aqueous VOC solutions were maintained at 27, 32, 38 and 42 degrees C to determine the gaseous concentrations at equilibrium (Cg*) and pc of VOCs, using the formula pc=(Cg*/CL). Results reveal that the pc values of all tested components increase slowly with Tw given a constant CL, and that the pc of alcohols and MEK fall as CL increases at a constant Tw. In contrast, the pc of toluene is not significantly impacted by a variation in CL at a constant Tw. However, the effect of CL concentration has seldom been discussed. The heats of liquid and gaseous phase transfer (DeltaHtr) of VOC, and the highly linear regression (with squared correlation coefficients, R2, from 0.901 to 0.999) between lnCg* and Tw(-1) are also evaluated. The experimental results and the VOC mass transfer characteristics are helpful for evaluating the emission of VOC from the water surface of wastewater treatment facilities.

VOC emission characteristics of petrochemical wastewater treatment facilities in southern Taiwan.

The wastewater treatment plants (WWTPs) of three representative petrochemical plants in southern Taiwan were sampled to investigate their VOC emission characteristics. Generally, emissions decline along the process flow, while the VOC concentration accumulates to as much as around 2400mg/m3 (as total hydrocarbons) at several closed vessel vents during the primary treatment. VOC emission rates (g/s) and fluxes (g/m2 hr) exhibit a similar trend of reducing concentrations in the WWTPs. From the field analysis data. VOC emission potential is best indicated by the concept of emission flux rather than concentration or emission rate. The Water 8 emission model version 4, developed by the U.S. EPA in 1995, was used to simulate the emission rate. The output results were compared to the calculated VOC liquid-gas mass equilibrium based essentially on the saturated gas concentration (Cg*) of the individual VOC components in wastewater. The comparisons clearly identified the proposed mass transfer approach using (Cg* as a reliable timesaving alternative to Water 8, which requires numerous input parameters and water analysis data.

Performance Characteristics of a Regenerative Catalytic Oxidizer for Treating VOC-Contaminated Airstreams.

A pilot apparatus of a regenerative catalytic oxidizer (RCO) equipped with two electrical heaters and two 20-cm i.d. × 200-cm height regenerative beds was used to treat methyl ethyl ketone (MEK) and toluene, respectively, in an airstream. The regenerative beds were packed with gravel (approximate particle size 1.25 cm, specific area 205 m2/m3, and specific heat capacity 840 J/kg °C) as a solid regenerative material and K-type thermal couples for measuring solid and gas temperatures, respectively. The catalyst bed temperature was kept around 400 °C and the gas superficial velocity was operated at 0.234 m/sec. This investigation measured and analyzed distributions of solid and gas temperatures with operating time and variations of volatile organic compound (VOC) concentrations in the regenerative beds. The overall VOC removal efficiency exceeded 98% for MEK and 95% for toluene. Degradation of VOCs will exist for MEK on the surface of solid material (gravel) in the temperature range of 330-400 °C, but toluene does not exhibit this phenomenon.