Levels Of Total Hydrocarbons Research Articles

Association Between Long‑Term Exposure to Air Pollution and the Rate of Mortality After Hip Fracture Surgery in Patients Older Than 60 Years: Nationwide Cohort Study in Taiwan.

To enhance postoperative patient survival, particularly in older adults, understanding the predictors of mortality following hip fracture becomes paramount. Air pollution, a prominent global environmental issue, has been linked to heightened morbidity and mortality across a spectrum of diseases. Nevertheless, the precise impact of air pollution on hip fracture outcomes remains elusive. This retrospective study aims to comprehensively investigate the profound influence of a decade-long exposure to 12 diverse air pollutants on the risk of post-hip fracture mortality among older Taiwanese patients (older than 60 years). We hypothesized that enduring long-term exposure to air pollution would significantly elevate the 1-year mortality rate following hip fracture surgery. From Taiwan's National Health Insurance Research Database, we obtained the data of patients who underwent hip fracture surgery between July 1, 2003, and December 31, 2013. Using patients' insurance registration data, we estimated their cumulative exposure levels to sulfur dioxide (SO2), carbon dioxide (CO2), carbon monoxide (CO), ozone (O3), particulate matter having a size of <10 μm (PM10), particulate matter having a size of <2.5 μm (PM2.5), nitrogen oxides (NOX), nitrogen monoxide (NO), nitrogen dioxide (NO2), total hydrocarbons (THC), nonmethane hydrocarbons (NMHC), and methane (CH4). We quantified the dose-response relationship between these air pollutants and the risk of mortality by calculating hazard ratios associated with a 1 SD increase in exposure levels over a decade. Long-term exposure to SO2, CO, PM10, PM2.5, NOX, NO, NO2, THC, NMHC, and CH4 demonstrated significant associations with heightened all-cause mortality risk within 1 year post hip fracture surgery among older adults. For older adults, each 1 SD increment in the average exposure levels of SO2, CO, PM10, PM2.5, NOX, NO, NO2, THC, NMHC, and CH4 corresponded to a substantial escalation in mortality risk, with increments of 14%, 49%, 18%, 12%, 41%, 33%, 38%, 20%, 9%, and 26%, respectively. We further noted a 35% reduction in the hazard ratio for O3 exposure suggesting a potential protective effect, along with a trend of potentially protective effects of CO2. This comprehensive nationwide retrospective study, grounded in a population-based approach, demonstrated that long-term exposure to specific air pollutants significantly increased the risk of all-cause mortality within 1 year after hip fracture surgery in older Taiwanese adults. A reduction in the levels of SO2, CO, PM10, PM2.5, NOX, NO, NO2, THC, NMHC, and CH4 may reduce the risk of mortality after hip fracture surgery. This study provides robust evidence and highlights the substantial impact of air pollution on the outcomes of hip fractures.

Evaluation of total hydrocarbon levels in various fish species

Evaluation of total hydrocarbon levels in various fish species

Association of exposure to hydrocarbon air pollution with the incidence of atopic dermatitis in children

BackgroundThere is growing evidence suggesting that air pollution may act as an important environmental risk factor in the development and aggravation of childhood atopic dermatitis (AD).MethodsWe collected data from the Taiwan National Health Insurance (NHI) research database and linked the data to the Taiwan Air Quality-Monitoring Database. From January 1, 2000 to December 31, 2012; children aged below 18 years were selected from the database and followed longitudinally until the diagnosis of AD, withdrawal from the NHI, or December 31, 2012. Children with missing data or those diagnosed with AD before enrolment in this study were excluded. We measured the incidence rate and hazard ratios (HRs) for AD and stratified them by quartiles (Q1–Q4) of air pollutant concentration. Multivariable Cox proportional hazards models were also applied by adjusting for age, sex, monthly income, and level of urbanization.ResultsWhen compared with the concentrations of pollutants in the Q1 quartile, the adjusted HR for AD increased with an increase in the exposure concentrations of total hydrocarbons (THCs), non-methane hydrocarbons (NMHCs), and methane (CH4) from 1.65 (95% confidence interval [CI]: 1.47–1.84) to 10.6 (95% CI: 5.85–7.07), from 1.14 (95% CI: 1.06–1.24) to 2.47 (95% CI: 2.29–2.66), and from 1.70 (95% CI: 1.52–1.89) to 11.9 (95% CI: 10.8–13.1), respectively. Patients exposed to higher levels of THCs, NMHCs, and CH4 exhibited greater incidence rates of childhood AD.ConclusionsThe present study demonstrated that exposure to higher concentrations of THCs, NMHCs, and CH4 were associated with an increased risk of childhood AD.

Association Between Air Pollution and the Risk of Uveitis: A Nationwide, Population-Based Cohort Study.

Previous studies have revealed an association between ocular surface disorders and air pollution, few studies have focused on the risk of uveitis. We aimed to investigate whether air pollution increases the risk of uveitis. We used the Taiwan Longitudinal Health Insurance Database (LHID) and the Taiwan Air Quality Monitoring Database (TAQMD) to conduct a retrospective cohort study. Air pollutant concentrations, including those of carbon dioxide (CO2), were grouped into four levels according to quartiles. The outcome was the incidence of uveitis, as defined in the International Classification of Diseases, Ninth Revision. We used univariable and multivariable Cox proportional hazard regression models to calculate the adjusted hazard ratios (aHRs) and determine the potential risk factors of uveitis. Overall, 175,489 subjects were linked to their nearby air quality monitoring stations. We found that for carbon monoxide, the aHRs of uveitis risk for the Q3 and Q4 levels were 1.41 (95% confidence interval (CI) = 1.23–1.61) and 2.19 (95% CI = 1.93–2.47), respectively, in comparison with those for the Q1 level. For nitric oxide, the aHRs for the Q3 and Q4 levels were 1.46 (95% CI = 1.27–1.67) and 2.05 (95% CI = 1.81–2.32), respectively. For nitrogen oxide (NOx), the aHRs for the Q2, Q3, and Q4 levels were 1.27 (95% CI = 1.11–1.44), 1.34 (95% CI = 1.16–1.53), and 1.85 (95% CI = 1.63–2.09), respectively. For total hydrocarbon (THC), the aHRs for the Q2, Q3, and Q4 levels were 1.42 (95% CI = 1.15–1.75), 3.80 (95% CI = 3.16–4.57), and 5.02 (95% CI = 4.19–6.02), respectively. For methane (CH4), the aHRs for the Q3 and Q4 levels were 1.94 (95% CI = 1.60–2.34) and 7.14 (95% CI = 6.01–8.48), respectively. In conclusion, air pollution was significantly associated with incidental uveitis, especially at high THC and CH4 levels. Furthermore, the uveitis risk appeared to increase with increasing NOx and THC levels.

Another insight into the contamination levels at Ogoniland in Niger Delta, Nigeria, with focus on Goi Creek.

Environmental pollution arising from crude oil exploratory activities has adversely impacted both the living and non-living components of the ecosystem. An insight into the impact of such activities with focus on Goi Creek in Ogoniland was provided in this study. We generated reliable data for physicochemical, heavy metal, and total hydrocarbon levels in the creek via a total of 40 samples collected across 4 stations designated within the creek in a duration of 10 months. With the exception of temperature, total dissolve solid, dissolved oxygen, chloride, sulfate, nitrate, zinc, and vanadium, the levels of other regulated parameters in the samples were not compatible with the national and international guidelines and standards for surface water quality including Federal Ministry of Environment Guidelines and standards for water quality in Nigeria and Environmental Protection Agency National recommended water quality criteria, respectively. The principal components (PCs) 1 and 2 of principal component analysis biplot revealed that the concentrations of the physicochemical parameters showed a mixed distribution among the stations; however, the heavy metals were more localized to station 4. Moreover, the dataset was subjected to water quality index (WQI), contamination index (Cd), heavy metal evaluation index (HEI), trace element toxicity index (TETI), and environmental water quality index (EWQI) to determine the extent of contamination. The result showed poor WQI, high contamination for Cd, and low-to-medium contamination for HEI. Although, there were variations among the stations on the contamination level, uniform remediation method should be adopted due to the similarity of the contaminants in all the stations.

Characteristics of non-methane hydrocarbons and methane emissions in exhaust gases under natural-gas/diesel dual-fuel combustion

In dual-fuel combustion, the levels of total hydrocarbon (THC) emissions have increased, unlike the neat diesel compression ignition (CI) combustion. Intuitively, it can be inferred that most THC emissions are produced by the crevice effect of low-reactivity fuels (high-volatility fuels) under dual-fuel combustion. Additionally, it is possible that high levels of THC emissions are produced by dual-fuel combustion. If reactivity-controlled compression ignition (RCCI) combustion is applied by advancing the diesel injection timing to improve the premixing conditions, the occurrence of the wall-wetting effect may induce the production of high levels of THC emissions owing to incomplete combustion. Thus, in this study, the characteristics of non-methane hydrocarbons (NMHC) and methane emissions under general dual-fuel combustion conditions (diesel injection timings before top dead center (BTDC) 0 and 30 crank angle degree (CAD)) and RCCI conditions (diesel injection timings at 60 and 84 CAD BTDC) were investigated under a low-load in a 6-L heavy-duty engine.The natural gas fraction varied from 50% to the maximum level considering the combustion stability (coefficient of variance of indicated mean effective pressure). The results revealed that the overall THC emissions from the general dual-fuel combustion were higher compared with those of RCCI combustion, owing to the methane emissions from the squish area and the lower average in-cylinder temperature. Notably, methane emissions were dominant in the THC emissions (52–87%) under the general dual-fuel combustion condition, while NMHC emissions were a major part of the in THC emissions (61–87%) under the RCCI regimes. Hence, combustion inefficiency is a major concern in dual-fuel combustion. In this study, this problem was resolved by advancing the diesel injection timings. The findings in this study can be useful in the design of oxidation catalysts, regardless of whether the combustion regime is a general dual-fuel combustion or RCCI combustion considering the portion of methane emissions in the exhaust gas. Additionally, it is known that the RCCI combustion is superior to the general dual-fuel combustion with respect to higher thermal efficiency and low harmful THC emissions.

Physicochemical Characterization of a liquid Effluent from a Refinery

The physicochemical profile of wastewater from a Refinery in the Niger Delta was evaluated to ascertain efficiency of wastewater treatment methods applied using standard analytical methods. In all samples, temperature ranged between 26.45 – 28.65 º C while the pH values of the untreated and treated wastewater samples were 8.39 ± 0.04 and 7. 82 ± 0.02 respectively. Total dissolved solids and observed total hydrocarbon levels gave maximum values of 172 mg/L and 11.35 mg/L respectively. The turbidity values for untreated and treated wastewater samples were 7.55 ± 0.08 and 3.49 ± 0.01 NTU respectively. The results revealed that the untreated wastewater sample had a higher concentration of phenol (28.46 ± 1.23) when compared to those (9.34 ± 0.89) of the treated wastewater sample while the cyanide content was relatively higher when compared to the limits set by World Health Organization for such effluents. Although substantial improvements were obvious in some water quality indices with treatment, high concentration of major effluent pollutants, phenol and total hydrocarbon content in the treated wastewater is indication of ineptitude in the effluent management system and calls for immediate intervention Keywords: Refinery effluent; Water treatment; Contaminants in wastewater; Water quality.

Deepwater Horizon oil spill exposures and neurobehavioral function in GuLF study participants

IntroductionThe 2010 Deepwater Horizon (DWH) disaster exposed tens of thousands of oil spill response and cleanup (OSRC) workers to hydrocarbons and other hazardous chemicals. Some hydrocarbons, such as toluene and hexane, have been found to have acute adverse effects on the central nervous system in occupational settings. However, no studies have examined the association between oil spill exposures and neurobehavioral function. MethodsWe used data from the Gulf Long-term Follow-up Study, a cohort of adults who worked on the DWH response and cleanup. Total hydrocarbon (THC) exposure attributed to oil spill cleanup work was estimated from a job-exposure matrix linking air measurement data to detailed cleanup work histories. Participants were also categorized into 6 job categories, or OSRC classes, based on their activity with the highest exposure. Neurobehavioral performance was assessed at a clinical exam 4–6 years after the spill. We used multivariable linear regression to evaluate relationships of ordinal THC levels and OSRC classes with 16 neurobehavioral outcomes. ResultsWe found limited evidence of associations between THC levels or OSRC classes and decreased neurobehavioral function, including attention, memory, and executive function. Workers exposed to ≥3 ppm THC scored significantly worse (difference1.0–2.9ppm = -0.39, 95% confidence interval (CI) = -0.74, −0.04) than workers exposed to <0.30 ppm THC for the digit span forward count test. There was also a possible threshold effect above 1 ppm THC for symbol digit test total errors (difference1.0–2.9ppm = −0.56 (95% CI = −1.13, −0.003), difference≥3.0ppm = −0.55 (95% CI = −1.20, 0.10)). Associations appeared to be stronger in men than in women. A summary latency measure suggested an association between more highly exposed jobs (especially support of operations workers) and decreased neurobehavioral function. ConclusionOSRC-related exposures were associated with modest decreases in neurobehavioral function, especially attention, memory, and executive function.

Understanding ozone formation at two islands of Rio de Janeiro, Brazil

This study was to evaluate the influence of vehicular emissions on two islands located in the Guanabara Bay, Metropolitan Area of Rio de Janeiro city, one of them without the presence of vehicles (Paquetá Island - PI) and another with a considerable fleet (Governador Island - GI). The data used correspond to the hourly averages of the years 2012 and 2013 for nitrogen oxides (NOx, NO2 and NO), ozone (O3), carbon monoxide (CO), total hydrocarbons (THC), aromatic hydrocarbons (BTEX), as well as meteorological data. To interpret the results, a multivariate statistic was used in order to characterize the impact of the vehicle fleet on air quality. The results showed that CO and NOx levels were 2–6 times higher in GI than PI. On the other hand, THC levels were similar at both sites. Surprisingly, O3 levels were up to 1.5 times greater in PI than in GI. The possible explanation for these higher levels is related to the formation process from THC and NOx in the presence of sunlight. The THC/NOx and NOx/NO ratios for PI are much higher than those found for GI, thus explaining the high ozone values for a location with virtually no vehicle fleet and industrial activities. The benzene, toluene and xylene levels at both sites were of the same magnitude order, however, ethyl benzene was about 7-fold higher in PI.

Improvement of dual-fuel biodiesel-producer gas engine performance acting on biodiesel injection parameters and strategy

Dual-fuel biodiesel-producer gas combustion has shown potential in reducing nitric oxides and particulate emission levels compared to only diesel operation; however, engine overall efficiency is slightly penalized, while the main drawbacks are represented by the higher levels of total hydrocarbons and carbon monoxide emissions.In this work, the improvements in the combustion development deriving from the splitting of the liquid fuel injection at low loads have been assessed using a 0.51L single-cylinder research diesel engine equipped with a high pressure common rail injection system and operated in dual-fuel mode. In this case, a synthetic producer gas was used as inducted gaseous fuel, while biodiesel was used as pilot fuel.Initially, the spray morphology was characterized in a constant-volume vessel for different values of injection duration and pressure, as well as vessel backpressure.Then, the experimental campaign, run on the engine at 1500rpm, was divided in two sessions. During the former, only one pilot injection of constant fuel amount (11mm3/cycle) was performed, the rail pressure was set equal to 500 or 1000bar, the injection timing was varied in the range −50÷5 degrees crank angle after top dead center while the amount of gaseous fuel inducted in the cylinder was varied on three levels. During the latter, the pilot fuel amount, kept equal to the one pilot injection tests, was split in two smaller injections and the effect of the dwell between them – varied in the range 5÷50 degrees crank angle – was investigated as well.The results of the first set of experiments revealed that pilot injection timing and pressure both affect the combustion development. This resulted in sensible variations on thermal and combustion efficiencies, and therefore on fuel conversion efficiency, the last one exhibiting higher values with pilot injection timing slightly advanced respect to top dead center and lower injection pressure. In these conditions, total hydrocarbons and carbon monoxide are lowered, while nitric oxides are increased. The amount of gas demonstrated to have a secondary effect on combustion development and emissions levels at the exhaust.Splitting pilot injection, demonstrated to be an effective way to increase fuel conversion efficiency and to reduce the levels of all the pollutant species compared to the single pilot injection strategy. Based on the extensive experimental activity described in this paper, a dwell ranging between 10 and 30 degrees of crank angle, combined with a first injection timing ranging between 35 and 20 degrees of crank angle before top dead center guarantee the highest fuel conversion efficiency and the lowest pollutants emission levels. Injection pressure confirmed to be a significant factor in affecting the combustion development, while a secondary effect was determined by the gaseous mass inducted in the cylinder.Ultimately, pilot injection splitting demonstrated to be an effective way for improving gaseous fuel combustion in dual-fuel mode at low load (lean mixture) conditions.

The use of a 0.20 μm particulate matter filter decreases cytotoxicity in lung epithelial cells following air-liquid interface exposure to motorcycle exhaust

This study was designed to investigate whether the use of a 0.20 μm particulate matter (PM) filter reduced the cytotoxicity induced by motorcycle exhaust (ME), a mixture of gases and particles, in lung epithelial cells cultured in air-liquid interface (ALI) inserts. The concentrations of PM, carbon monoxide, carbon dioxide, total hydrocarbons (THC), total volatile organic compounds, and nitrogen oxides in both filtered ME (fME) by a 0.20 μm filter and non-filtered ME (non-fME) were measured. Lung epithelial cells were exposed to clean air, fME, or non-fME in the ALI chamber. Cell relative viabilities (CRV) and the reactive oxygen species (ROS) generation were determined. Our results revealed that PM2.5 was the main compound of PM in ME. After filtration, PM and THC levels were significantly reduced, as compared with non-fME. When compared with the clean air exposed group, the CRV in both fME and non-fME-exposed group was significantly reduced (p < 0.001), while their ROS generation were markedly increased (p < 0.001). When compared with non-fME-exposed group, the CRV and ROS generation were significantly improved following fME exposure (p < 0.05). As a result, of PM and THC concentrations were decreased approximately 90% and 22.71%, respectively, the CRV was improved from 40.4% (non-fME) to 55.7% (fME), and the increased ROS generation by non-fME was decreased about 51.6%. When BEAS-2B cells were exposed to fME, a time-dependent reduction in CRV was observed. In conclusion, our findings suggest that ME-exposure in the ALI system induces cytotoxicity and oxidative stress responses. The addition of a 0.20 μm PM filter significantly modifies the particulate composition in PM and the concentration of THC, and shows protective effects by improving the survival of exposed lung epithelial cells and reducing the ROS generation. Therefore, emission factors such as different size of PM and THC from motorcycles may play a role in ME-induced toxicity.

Combustion and Emission Characteristics According to the Fuel Injection Ratio of an Ultra-Lean LPG Direct Injection Engine

The effect of the fuel injection ratio on the combustion and emission characteristics of stratified lean mixture combustion was investigated for a spray-guided liquefied petroleum gas (LPG) direct injection engine. Inter-injection spark-ignition combustion—a specially designed combustion strategy for LPG fuel derived from a two-staged injection—was employed to maximize the improvement in thermal efficiency when combustion stability is secured. When changing the fuel injection ratio, the optimum spark advance and fuel injection timings were experimentally determined to maximize the thermal efficiency based on sweeping timings. The optimum fuel injection ratio with the highest thermal efficiency (42.76%) and stable operation was 60%/40%, with the optimization of the spark advance and fuel injection timing, because of the locally rich mixture region in the recirculation zone. NOx emissions were at their highest level with a fuel injection ratio of 60%/40% because of the high combustion temperature, and the levels of total hydrocarbon and CO emissions with 50%/50% and 60%/40% fuel injection ratios were similar, whereas emissions at 70%/30% were significantly higher because of fuel wetting and the formation of over-lean mixture.

Alteration in antioxidant genes expression in some fish caught from Jeddah and Yanbu coast as a bio-indicator of oil hydrocarbons pollution.

The mRNA expression profile of some antioxidant genes in skin, gills, livers, and muscles of Siganus canaliculatus and Epinephelus morio was used as an indicator of petroleum hydrocarbons pollution in six areas at Jeddah and Yanbu coasts in KSA. Total petroleum hydrocarbons (TPHs) were determined in both sea water and sediments collected from the studied areas. The mRNA expression levels of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) were determined. The highest level of total petroleum hydrocarbons was observed in front of the petromine refinery at Jeddah and in S. canaliculatus when compared to E. morio. There was a significant high expression level of studied antioxidant enzymes genes in the polluted areas and the level of the expression profile tended to correlate with the degree of pollution and fish species feed habit. This was confirmed by the level of MDA which in the same way increased with an increase in the level of total hydrocarbons. In conclusion; the expression profile of antioxidant enzymes of S. canaliculatus and E. morio tissues can be used as a strong bio-indicator of total hydrocarbons pollution especially in S. canaliculatus.

Fractionation of engine exhaust hydrocarbons using flame ionization detection with variable temperature sample conditioner

The flame ionization detector is a standard instrument for measuring total hydrocarbon concentration in engine exhaust. Engine combustion modes such as diesel low-temperature combustion are known to produce higher levels of total hydrocarbon than conventional combustion modes, and a need exists to estimate species that may nucleate into nanoparticles upon dilution in the atmosphere. Exhaust hydrocarbon fractionation is useful for gaining better understanding about engine combustion and for developing aftertreatment catalysts for reducing emissions. Methods capable of measuring individual hydrocarbon species such as gas chromatography and Fourier transform infrared spectrometry do not measure the full range of species present in engine exhaust and are expensive. In this work, a custom-designed variable temperature sample conditioner was developed for use with two fast-response flame ionization detectors to fractionate the hydrocarbons present in engine exhaust as a function of component volatility. A condensation model for fuel alkanes was also developed to be used in concert with the experimental data to determine the fraction of fuel-like hydrocarbons within the total hydrocarbon measurement. Our results indicate that the variable temperature flame ionization detector method yields similar unburned hydrocarbon fraction to reported literature values using more extensive speciation studies at similar engine conditions. We find that while low-temperature combustion engine operation emits higher concentrations of total hydrocarbon than conventional combustion modes, the fraction of less volatile hydrocarbon species is higher for lower engine load, regardless of the combustion mode.

Study of regulated emissions and nanoparticle characteristics of light-duty direct-injection vehicles fuelled with gasoline and liquefied petroleum gas in the New European Driving Cycle and the Federal Test Procedure 75 driving cycle

This study evaluated the pollutants and nanoparticles, the fuel economy and the levels of carbon dioxide emissions of vehicles equipped with a 1.6 l direct-injection spark ignition engine fuelled by gasoline or by liquefied petroleum gas. The nanoparticles were analysed using a particle measurement system that is used in Europe for regulatory purposes. A fast-response particle size and number spectrometer (model DMS500) were used to characterize the size-resolved particle distributions. The vehicle was tested on a chassis dynamometer for the New European Driving Cycle and Federal Test Procedure 75 in its factory default state (gasoline version) and modified state (for liquefied petroleum gas fuel), and the results were compared. The liquefied-petroleum-gas direct-injection vehicle emitted significantly lower levels of total hydrocarbons than did the gasoline direct-injection vehicle. However, the levels of nitrogen oxide emissions from the liquefied-petroleum-gas direct-injection vehicle were equivalent to those from the gasoline direct-injection vehicle. Because of the higher combustion and exhaust temperatures and relatively higher loads imposed during the driving cycles, the liquefied-petroleum-gas direct-injection vehicle showed a slightly higher level of nitrogen oxide emissions. The particle emissions from the vehicles were mainly affected by the vehicle driving conditions of the test driving cycles. In particular, the particle emissions from the vehicle were pronounced in the cold-start and accelerating phases of the emission certification standards. The nanoparticles from the liquefied-petroleum-gas direct-injection vehicle were significantly fewer in number, exhibiting a reduction of over 99%.

Speciation of organic compounds in aerosols from urban background sites in the winter season

Winter aerosol samples were daily collected during one-month long campaign in Oporto and Coimbra. The high-volume PM2.5 samples were solvent extracted and their organic content separated into several functional groups, which were then analysed by gas chromatography–mass spectrometry. The organic compounds identified and quantified revealed some differences between samples from the two urban areas. In general, the levels of total hydrocarbons in the urban background station of Oporto were higher than those of Coimbra. Concentration ratios between specific compounds and the presence of molecular markers derived from petroleum, such as hopanes, pristane and phytane, point out vehicles as the main source of pollutants. The contribution of biogenic compounds, mainly hydrocarbons associated with the waxy cuticle of vegetation, is also observable in both cities. The benzo[a]pyrene equivalent daily values were frequently higher than 1ngm−3 in Oporto suggesting an additional cancer risk for the population. The PM2.5 mass attributable to vehicle emissions is higher in the background atmosphere of Oporto than in Coimbra. On weekends, biomass burning emissions could represent up to 74% of the organic carbon content of the urban aerosols.

Grey-box modeling of HCCI engines

Homogenous Charge Compression Ignition (HCCI) holds promise to increase indicated thermal efficiency and reduce Nitrogen Oxides (NOx) and Particulate Matter (PM) emissions from internal combustion engines. Lack of a direct means to initiate the combustion and high levels of Total Hydrocarbon (THC) and Carbon Monoxide (CO) emissions are major drawbacks associated with HCCI engines. Control of combustion phasing for optimum indicated thermal efficiency and minimizing emissions are vital for putting HCCI engines into practice. One major challenge is to develop accurate models for understanding engine performance, as those models can run real-time for HCCI control. This paper develops the first computationally efficient grey-box model for predicting major HCCI engine variables. The grey-box model consists of a combination of physical models and three feed-forward artificial neural networks models to estimate six major HCCI variables including combustion phasing, load, exhaust gas temperature, THC, CO, and NOx emissions. The grey-box model is experimentally validated over a large range of HCCI engines operation including 309 steady state and transient test conditions. The validation results show that the grey-box model is able to predict the HCCI engine outputs with average relative errors less than 10%. Performance of the grey-box methodology is tested for two different HCCI engines and the verification results show that the developed six-output grey-box model can be successfully used for performance modeling of different HCCI engine applications.

Network monitoring of speciated vs. total non-methane hydrocarbon measurements

The total non-methane hydrocarbon (TNMHC) level in the atmosphere is defined as the level of total hydrocarbons minus the level of methane. TNMHC observations are made in selected air quality stations (AQS) of Environmental Protection Agency (EPA) across Taiwan. The AQS network is also complemented by a network of photochemical assessment monitoring stations (PAMS) to provide hourly observations of 56 speciated non-methane hydrocarbons (NMHCs). In this study, the relationship between the AQS and PAMS TNMHC values was cross-examined for the period of 2007–2011 at four sites that conducted both types of measurements. Although the two observations differ in their methods of collection, the variations in the two datasets showed high synchronicity. However, because some of the NMHCs were missed in the summation of 56 species, the PAMS TNMHC values were consistently lower than those of the AQS TNMHC by an average of 30%.Although total hydrocarbon (THC) instruments can provide instantaneous TNMHC mixing ratios (by subtracting methane) to approximate the levels of volatile organic compounds (VOCs), they lack speciated information, which is invaluable to establishing the link between the observation site and specific source influences. In contrast, PAMS observations with speciation information can be used to complement this deficiency. Examples of this complementarity were illustrated by comparing four common sites, with two mainly affected by urban/traffic emissions and two primarily affected by industrial emissions. The chemical composition of the air samples varied significantly between the four sites. Ethylene and propylene were found to be prominent at the two industrial sites, linking these samples strongly to the petrochemical industry nearby. This compositional signature was even more pronounced for the sample peak values. These findings suggest that network monitoring of TNMHCs may not be sufficient, and the lack of compositional information can be complemented by the more elaborate monitoring means such as PAMS deployed only at critical sites to provide both area coverage and speciation knowledge.

Performance of a Direct Injection of IC Engine on SVO and Biodiesel from Multiple Feedstocks

Straight Vegetable Oil (SVO) is a promising biofuel with a low energy input to energy output ratio. Successful use of SVO in engines depends on engine performance, wear and emissions. This study focuses on short term engine emissions and performance. This research uses oils produced in Colorado as a full diesel fuel substitute in a modified single cylinder engine. This engine testing was conducted in the laboratory. The test engine was a Yanmar TF140E, which is naturally aspirated and uses low pressure (～140 bar) mechanical direct injection. The engine fuel system was modified to accommodate a 2-tank custom SVO kit. The SVO was heated to 75 °C. Fuel economy and emissions measurements were performed for petroleum diesel, four different vegetable oils (sunflower, canola, camelina, and soybean) and their biodiesel derivatives. Fuel mass flow, oxides of nitrogen (NOX), total hydrocarbons (THC), carbon monoxide (CO), and particulate matter were measured. No engine degradation was experienced through approximately 50 hrs of testing on SVO and 50 hrs of testing on biodiesel. Overall engine emissions for SVO and biodiesel, with the exception of THC for biodiesel, were higher than petroleum diesel. More favorable biofuel emissions comparisons to diesel are expected with other engine designs based on data from various literature sources. Data comparing raw and refined SVO indicate that refined vegetable oil produces lower particulate matter (PM) emissions. General trends were observed showing that oils with higher levels of polyunsaturated fats (e.g. C18:1, C18:2, and C18:3) produce higher levels of NOX and THC’s.

Bioaccumulation of some Heavy Metals and Total Hydrocarbon (THC) in the Tissues of Periwinkle (Tympanotonus Fuscatus Var Radula) in the Intertidal Regions of Qua Iboe River Basin, Ibeno, Akwa Ibom State, Nigeria

The levels of some heavy metals and total hydrocarbon (THC) in the tissues of periwinkle ( Tympanotomus fuscatus ) from Qua Iboe River, Ibeno area in Akwa Ibom State were investigated. Three hundred samples of periwinkles were collected for a period of three months from two stations (Mkpanak-control and Itak Abasi-downstream) in the intertidal region of the River and were analyzed using Atomic Absorption Spectrophotometry for the determination of heavy metals and Soxhlet extraction gravimetric method was used in determination of total hydrocarbon. The mean levels of total hydrocarbon varied from 0.004-0.050 mg/g and the mean level of heavy metals also varied: Cadmium (Cd), 0.0430.53mg/g, Copper (Cu), 0.02-0.027mg/g, lead (Pb), 0.060-0.067mg/g, Mercury (Hg), 0.020-0.033mg/g, Nickel (Ni), 0.030.04mg/g in all the stations. The levels of heavy metals and total hydrocarbon during the study period in all stations across the months did not show significant difference (p> 0.05). This was attributed to the fact that, they were less industrial activities and close proximity of the stations to the major road where emissions from automobiles are abounded which is purely a residential area. These studies demonstrate that, the evidence of bioaccumulations of heavy metals and total hydrocarbons were below the recommended tolerable levels when compared to that of Federal Ministry of Environment. This implies that periwinkles from Qua Iboe River, Ibeno are safer now than before as a food source for consumers who delight in this delicacy. However, constant monitoring of water bodies receiving effluents is emphasized in order to forestall cumulative effects of pollutants which may lead to sub-lethal consequences in the aquatic fauna and clinical poisoning to man.