Petrochemical Industrial Complex Research Articles

Partitioning and mobility behavior of metals in road dusts from national-scale industrial areas in Korea

In this study, we investigated the characteristics of heavy metal contamination in road dusts collected from industrial areas in Korea. A total of 12 sampling sites, including nine sites in three different industrial complexes (ICs), two IC vicinity areas and one background area, were selected for this study. The collected road dusts were divided into four categories. The heavy metals (Cd, Cu, Pb, Zn, and Ni) were extracted from the road dust by an aqua regia extraction method and analyzed by atomic absorption spectrometry. The highest concentrations of Cd, Cu, and Pb were identified in road dusts from areas near the non-ferrous metal IC, followed by those from the petrochemical IC. The petrochemical IC and the mechanical/shipbuilding IC showed the highest concentrations of Ni and Zn in their road dusts, respectively. The concentration of heavy metals in the road dusts collected from the IC vicinity areas, even those located in a rural environment, were very high. The concentration of heavy metals increased with decreasing particle size of the road dusts. This study also analyzed the mobility of the heavy metals in the road dusts using partial sequential extraction with the Tessier procedure. The order of mobility identified, based on exchangeable and carbonate fractions of the heavy metals, was Cd > Zn > Pb > Cu > Ni.

Analysis of potential RDF resources from solid waste and their energy values in the largest industrial city of Korea

The production potential of refuse derived fuel (RDF) in the largest industrial city of Korea is discussed. The purpose of this study is to evaluate the energy potential of the RDF obtained from utilizing combustible solid waste as a fuel resource. The total amount of generated solid waste in the industrial city was more than 3.3 million tonnes, which is equivalent to 3.0tonnes per capita in a single year. The highest amount of solid waste was generated in the city district with the largest population and the biggest petrochemical industrial complex (IC) in Korea. Industrial waste accounted for 89% of the total amount of the solid waste in the city. Potential RDF resources based on combustible solid wastes including wastepaper, wood, rubber, plastic, synthetic resins and industrial sludge were identified. The amount of combustible solid waste that can be used to produce RDF was 635,552tonnes/yr, consisting of three types of RDF: 116,083tonnes/yr of RDF-MS (RDF from municipal solid waste); 146,621tonnes/yr of RDF-IMC (RDF from industrial, municipal and construction wastes); and 372,848tonnes/yr of RDF-IS (RDF from industrial sludge). The total obtainable energy value from the RDF resources in the industrial city was more than 2,240,000x10(6)kcal/yr, with the following proportions: RDF-MS of 25.6%, RDF-IMC of 43.5%, and RDF-IS of 30.9%. If 50% or 100% of the RDF resources are utilized as fuel resources, the industrial city can save approximately 17.6% and 35.2%, respectively, of the current total disposal costs.

Environmental pollution and bio-politics: The epistemological constitution in Japan’s 1960s

This article examines the epistemological reconstitution in Japan—from Eisei (hygiene) to Kankyo (environment and ecology)—in the 1960s, particularly focusing on Yokkaichi city in the Mie prefecture that was infamous for environmental pollution. Post World War II, Yokkaichi port and its petrochemical industrial complexes were regarded as a symbol of Japan’s development. Referred to as ‘a million dollar night’s view’ for its ability to provide light the entire day, it played a central role in the country’s industrial reconstruction. Due to its reputation for ‘nature’-filled countryside, many enjoyed swimming at Yokkaichi despite the presence of the nearby industrial plants. Both these facts imply that people did not realize the risks posed by the dirtiness of the wastewater and the fumes emitted by the plants, an ignorance that may be traced back to the epistemic constitution of hygiene in Japan at the time. Since modernization, the government had adopted the idea of hygiene to control infectious and venereal diseases. The Department of Interior in 1873, and later, the Ministry of Health and Welfare in 1938 were also instituted to discipline human aesthetics through bio-politics. In the 1960s, when diseases of unknown origins began to appear and ‘scientific’ researches made the risks of wastewater and fumes visible, a new idea, Kankyo (which included but went beyond that of hygiene), was implemented to mitigate these risks. This transition saw the landscape of ‘a million dollar night’s view’ being transformed into a symbol of injustice and became a basis for grassroots political acts.

석유화학공단과 화력발전소 주변지역 주민들이 인식하는 악취발생과 건강영향의 관련성 연구

This study investigated the health effects of offensive odor in residents living near the petrochemical industry complex area(PICA) and the thermoelectric power plant(TPP) by using questionnaire. Residents who felt the offensive odor were 58.3% at PICA, 50.9% at TPP and 24.4% at classical fishing and agrarian villages (CFAV)(p=0.000). People who answered that the offensive odor was sever at CFAV were 95.2% only on summer, but at PICA and TPP, were 44.1% and 57.3% on Spring, 62.4% and 68.8% on Summer, 22.0% and 31.7% on Autumn, and 21.7% and 25.7% on Winter, respectively. Average days that the odor occurred were 4.4 days/month at CFAV, but 12.0 and 9.5 days/month at PICA and TPP, respectively. People who experienced the sleep disturbance were 28.0% and 27.1% at PICA and TPP, respectively. The most frequently subjective symptoms were headache(0.953), frequently sneezing(0.825), itchy eyes(0.766), and stimulating eyes(0.709) at PICA, and headache(1.082), itchy eyes(0.931), itchy skin(0.826), and frequent sneezing(0.674) at TPP, respectively. At PICA and TPP, the occurrence rates of diseases in respondents' families were 15.4% and 15.6% for asthma, 12.4% and 9.2% for respiratory diseases, 27.8% and 31.2% for skin diseases, and 9.1% and 6.9% for nervous diseases, respectively. In conclusion, many residents who living near the PICA and TPP experienced the offensive odor during four seasons, especially high on summer, the most frequently subjective symptoms such as headache, itchy and stimulating eyes, frequently sneezing, and some diseases among their families such as asthma, respiratory diseases, skin diseases, and nervous diseases.

Assessing the impact of pollution on the Japaratuba river in Brazil using the Drosophila wing spot test

The Drosophila melanogaster somatic mutation and recombination test (SMART) was used to assess the genotoxicity of surface (S) and bottom (B) water and sediment samples collected from Sites 1 and 2 on the Japaratuba River (Sergipe, Brazil), an area impacted by a petrochemical industrial complex that indirectly discharges treated effluent (produced water) into the river. The genotoxicity tests were performed in standard (ST) cross and high bioactivation (HB) cross flies and were conducted on samples taken in March (dry season) and in July (rainy season) of 2003. Mutant spot frequencies found in treatments with unprocessed water and sediment samples from the test sites were compared with the frequencies observed for similar samples taken from a clean reference site (the Jacarecica River in Sergipe, Brazil) and those of negative (ultrapure water) controls. While samples from the Japaratuba River generally produced greater responses than those from the Jacarecica River, positive responses were detected for both the test and reference site samples. All the water samples collected in March 2003 were genotoxic. In July 2003, the positive responses were restricted to water samples collected from Sites 1 B and 2 S in the ST cross. The genotoxicity of the water samples was due to mitotic recombination, and the samples produced similar genotoxic responses in ST and HB flies. The spot frequencies found in the July water samples were considerably lower than those for the March water samples, suggesting a seasonal effect. The only sediment samples that were genotoxic were from Site 1 (March and July) and from the Jacarecica River (March). The genotoxins in these samples produced both somatic mutation (limited to the Site 1 sample in HB flies) and recombination. The results of this study indicate that samples from both the Japaratuba and Jacarecica Rivers were genotoxic, with the most consistently positive responses detected with Site 1 samples, the site closest to the putative pollution source.

PREVALENCE OF CHRONIC AUTOIMMUNE THYROIDITIS IN THE URBAN AREA NEIGHBORING A PETROCHEMICAL COMPLEX AND A CONTROL AREA IN SAO PAULO, BRAZIL

To evaluate the prevalence of chronic autoimmune thyroiditis in 2 urban areas of metropolitan São Paulo (Brazil): Polo Area neighboring a large petrochemical complex and São Bernardo Campo Area (control area). Subjects were randomly included from the adult population (20 to 70 years of age) of both genders (women 80%, men 20%) who voluntarily agreed to participate. From the Polo Area, in the vicinity of a large petrochemical industrial complex, 409 subjects were included; from the control area (São Bernardo Campo Area) 420 individuals were included. All subjects were clinically examined, and a detailed record of past thyroid illness and medications was obtained. Ultrasonographic studies were performed using a portable GE Medical Systems apparatus. Blood samples were obtained for free T4, serum TSH, and serum anti-thyroid peroxidase autoantibodies. Urine specimens were collected in Monovette syringes for assaying iodine content. Salt samples were collected at households, and the iodine content was measured. Chronic autoimmune thyroiditis was diagnosed both echographically (marked hypoechogenicity) and immunologically (presence of autoantibodies against thyroid peroxidase). In the Polo Area, 15.6% of the examined population had chronic autoimmune thyroiditis, and in the control area (São Bernardo Campo Area), 19.5% of the population had evidence of chronic autoimmune thyroiditis (P > 0.057, not significant). The prevalence of hypothyroidism was 4.9% in the Polo Area and 8.3% in the São Bernardo Campo Area (P = 0.0461 significant). Taking the 2 populations together, 6.6% had hypothyroidism (about one third of these patients were on L-T4 treatment). The mean thyroid volume was 11.2 mL. Domestic salt had a normal concentration of iodine (35.5 + 6.61 mg/kg). Urinary excretion of iodine was above 300 microg Iodine/L in 58.5% of the total population. The high iodine intake (above 300 microg Iodine/L of urine) that was present from 1998 through 2005 may be related to a higher prevalence of chronic autoimmune thyroiditis in both areas that were studied. There was no apparent or documented relationship of chronic autoimmune thyroiditis prevalence to the proximity to the petrochemical complex.

The piscine micronucleus test to assess the impact of pollution on the Japaratuba river in Brazil

In situ investigations of the effects of mutagenic pollutants (environmental monitoring) have increasingly used bioindicators, and fish often have been used in these studies as sentinel organisms. In the present study, we have used the piscine micronucleus test (MNT) as an in situ biological indicator of chemical contamination in two fresh water fish species (Astyanax bimaculatus and Hoplias malabaricus). The fish were collected from two sites (Sites 1 and 2) in the Japaratuba River (Sergipe, Brazil), in an area impacted by a petrochemical industrial complex which indirectly contributes treated effluent (produced water) to the river. Responses in fish from these sites were compared to fish from a clean reference site (Jacarecica River - Sergipe, Brazil). The results indicated an enhanced frequency of micronuclei (MN) in peripheral red blood cells of A. bimaculatus collected at Sites 1 and 2 when compared to their respective negative control (A. bimaculatus collected from the Jacarecica River). H. malabaricus collected at Sites 1 and 2 did not have a significant increase in MN. The results of this study indicate that the piscine MNT is a useful in vivo technique for the detection of chemical contaminants in the aquatic environment and that the assay shows potential for in situ monitoring of water quality. Nevertheless, the results also demonstrated differential sensitivity of A. bimaculatus and H. malabaricus to the induction of MN.

Assessment of the Petrochemical Industry Pollution on the Skikda Bay, Algeria

The Skikda bay is located in the northern part of Algeria. The area is in contact with a petrochemical industrial complex, which raw materials and final products contaminate the surrounding areas via atmospheric pollution as well as effluents, which are dumped into seawaters. To establish the effects of these pollutants and waste disposal on the vicinity of the bay, several samples were taken at different distances along the bay and the outfall pipes of the industrial complex. Subsequently, several chemical analyses were made to analyze the concentrations of hydrocarbons, CO[2], Ca(+2) and Mg(+2), chlorides and phosphates and the alkalinity present into the samples. Several concentrations of the above constituents are reported as a function of the different sites.

GULF COAST STUDY OF URBAN AIR POLLUTION AND RESPIRATORY FUNCTION (SURF)

ISEE-78 Introduction: The purpose of this study was to identify and evaluate exposure to and effects of urban air pollutants on respiratory function in an occupational cohort of beach lifeguards. This area of the Gulf Coast is adjacent to many point sources of air toxics, including major petrochemical industrial complexes and heavily trafficked roads and highways. It is also a consistent non-attainment area for compliance with number of days during which ozone concentrations exceed permissible levels. The need to determine health effects associated with air pollution has thus increased. Methods: The lifeguard occupational cohort includes >100 guards, ages 16-27, working 10-hour shifts and sustaining continuous ambient air exposures. A “natural” experiment was facilitated, given that guards are traditionally exposed to low levels of photochemically formed air pollutants during summer mornings and high levels (reaching seasonal peaks) in the afternoons. Three times daily, each lifeguard performed computerized spirometry, according to ATS standards, to measure air flow rates and lung volumes: in the morning prior to exercise (baseline), following a one-hour strenuous cardiovascular workout, and again in the afternoon following sustained exposure to ambient air. Each guard also completed an initial survey, detailing family and personal history of asthma, smoke exposure, and lung disease as well as daily surveys documenting potential confounders including recent illness, medication use, and smoke exposure. Hourly measurements of ozone, oxides of nitrogen, nitrogen dioxide, sulfur dioxide, and particulates (PM2.5) were obtained from a regulated monitoring site at the local airport. Meteorologic data collected include wind speed, wind direction, temperature, and relative humidity. Results: Univariate statistics revealed normally distributed data meeting assumptions of homogeneity of variance for ANOVA, which showed a significant difference (p<0.05) between morning and afternoon lung function measures. Linear regression revealed a significant decrease in FVC and FEV1 after exposure to increasing levels of PM2.5 for several hours. Discussion: Results indicate a decrease in total lung volume (preserved FEV1/FVC ratio) rather than typical patterns of airway obstruction due to bronchospasm as seen in asthma exacerbations (FEV1 reduced more than FVC)—even at relatively low levels of PM2.5. While federal air quality standards list PM2.5 levels >65 μg/m3 as unhealthy, we have seen average lung volumes decrease by as much as 0.5 liters (5-30%) with maximum PM2.5 concentrations of only 38 μg/m3. This may have implications for environmental recommendations and regulations as well as disease prevention, in that our data suggest that even tighter standards may be necessary.

광양만과 여수해만의 표층퇴적물에서 Nonylphenol의 오염에 관한 연구

This study was carried out to survey the pollution of nonylphenol (NP) in surface sediments around Gwangyang bay and Yeosu sound. NP was suspected chemicals as endocrine disruption. Gwangyang bay is located on the mid south coast of Korea. It is a semi-closed bay which Yeosu petrochemical industrial complex, POSCO (Pohang Steel Company) and Gwangyang container harbor are there. The surface sediments were collected at 15 stations with gravity corer at October, 1999, February, May and August, 2000. Also, the stream and intertidal sediment were collected at 5 sites at August, 2000. Concentrations of NP in surface sediments were in the range of 6.89 to 202.70 ng/g dry wt.. Seasonal range (mean value) of NP is 13.98 to 30.48 (23.46) ng/g dry wt. at October, 10.35 to 54.91 (28.10) ng/g dry wt. at February, 29.05 to 202.70 (82.32) ng/g dry wt. at May and 6.98 to 83.40 (25.37) ng/g dry wt. at August. NP was seasonally fluctuated, and the highest mean value and range was detected at May, 2000. NP was highly distributed in the inner part of Gwangyang bay than Yeosu sound. Concentrations of NP in stream and intertidal sediments showed the highest value in downstream near Yeosu petrochemical industrial complex and Yondung stream. It suggests that the source of NP is industrial wastewater and municipal sewage.

Sintolab: the REPSOL-YPF PID tuning tool

This paper describes a tuning tool for PID controllers. What makes this tool different to others available in the market is: (a) its ability to model the most important load disturbances, (b) its wide range of tuning methods that cover two types of specifications (features of time responses and features of frequency responses), (c) its possibilities in order to import or export data and to determine the more adequate control parameters exportable to the distributed control system. The calculated MISO model enables an improved tuning of the PID loop, both for the servo and regulatory cases. This is of special interest in the Petrochemical Industry where most of the PID controllers have a fixed design criterion, load disturbances rejection or setpoint following, like in model predictive control applications. This tool, which combines direct experience in the industry with the solid theoretical knowledge of a group of university researchers, is already being widely used in all the REPSOL-YPF refineries and some of its petrochemical industrial complexes.

Increased Risk of Preterm Delivery in Areas with Cancer Mortality Problems from Petrochemical Complexes

The petrochemical and petroleum industries are the main sources of industrial air pollution in Taiwan. Data in this study concern outdoor air pollution and the health of individuals living in communities in close proximity to petrochemical industrial complexes. The prevalence of delivery of preterm birth infants was significantly higher in mothers living near petrochemical industrial complexes than in control mothers living elsewhere in Taiwan. After controlling for several possible confounders (including maternal age, season, marital status, maternal education, and infant sex), the adjusted odds ratio was 1.18 (95% CI=1.04–1.34) for delivery of preterm infants in the petrochemically polluted region. The data provide further support for the hypothesis that air pollution can affect the outcome of pregnancy.

Industrial Impact on Marsh Soils at the Bahia Blanca Ria, Argentina

The Bahia Blanca Estuary is located in southern Buenos Aires province, Argentina. The area is linked to a petrochemical industrial complex, whose raw materials and final products contaminate the surrounding areas via atmospheric pollution and effluents, which are dumped in the estuary waters. To establish the effects of the industrial waste disposal on the nearest coastal soils, 17 samples were taken at different distances from the loading dock and the outfall pipes of the industrial complex. Later, the physicochemical characteristics of the soil samples, their hydrocarbon contents, sulfides, sulfates, Zn, Cu, and Pb were analyzed and a comparison was made to control samples, which were not affected by the industrial outfall. Hydrocarbons, Zn, Cu, and Pb contents were found at levels that modified the physical and chemical characteristics of the soils. The resistance to penetration shows that the thinner the film of water that surrounds the particles or aggregates, the smaller the migration of organic micelle, which settle on the surface of the contact material. This is demonstrated by the degree of cohesion reached by the particles and the strong influence on the index of hydrophobicity. The high porosity shows that the continuity of the porous space of the soil matrix is impeded by the presence of pollutants, which generate areas that are highly limiting to water flow. The oxidation-reduction potential and the low concentrations of soluble forms of Cu and Pb compared with their concentrations precipitated as sulfides confirm the action of the pollutants.

Industrial Impact on Marsh Soils at the Bahia Blanca Ria, Argentina

The Bahía Blanca Estuary is located in southern Buenos Aires province, Argentina. The area is linked to a petrochemical industrial complex, whose raw materials and final products contaminate the surrounding areas via atmospheric pollution and effluents, which are dumped in the estuary waters. To establish the effects of the industrial waste disposal on the nearest coastal soils, 17 samples were taken at different distances from the loading dock and the outfall pipes of the industrial complex. Later, the physicochemical characteristics of the soil samples, their hydrocarbon contents, sulfides, sulfates, Zn, Cu, and Pb were analyzed and a comparison was made to control samples, which were not affected by the industrial outfall. Hydrocarbons, Zn, Cu, and Pb contents were found at levels that modified the physical and chemical characteristics of the soils. The resistance to penetration shows that the thinner the film of water that surrounds the particles or aggregates, the smaller the migration of organic micelle, which settle on the surface of the contact material. This is demonstrated by the degree of cohesion reached by the particles and the strong influence on the index of hydrophobicity. The high porosity shows that the continuity of the porous space of the soil matrix is impeded by the presence of pollutants, which generate areas that are highly limiting to water flow. The oxidation–reduction potential and the low concentrations of soluble forms of Cu and Pb compared with their concentrations precipitated as sulfides confirm the action of the pollutants.

ADVERSE PREGNANCY OUTCOME IN A PETROCHEMICAL POLLUTED AREA IN TAIWAN

The petrochemical industry is the main source of industrial air pollution in Taiwan. Reported here are the results from an ongoing study of outdoor air pollution and the health of individuals living in a community in close proximity to petrochemical industrial complexes. The prevalences of term low birth weight (LBW) in the petrochemical municipality and control municipality were 3.22% and 1.84%, respectively. After controlling for several possible confounders (including maternal age, season, marital status, maternal education, and infant sex), the adjusted odds ratio was 1.767 (1.002-3.116) for term LBW in the petrochemical municipality. Data provide further support for the hypothesis that air pollution can affect the outcome of pregnancy.

Numerical study of atmospheric dispersion of a substance released from an industrial complex in the southern coast of Korea

Diurnal variations of wind field and pollutant dispersion in a complex terrain with a shoreline were investigated under the insolation conditions of summer and winter. The area is located in the south of the Korean Peninsula and includes a large petrochemical industrial complex. The Regional Atmospheric Modeling System (RAMS) was used in the simulation study. Initially, horizontally homogeneous wind fields were assumed on the basis of sounding data at the nearby upper-air station for days with morning wind speeds below 2 m s −1. On these days, the sea breeze prevailed in summer while the land breeze lasted for a few hours in the morning; the effect of synoptic winds was strong in winter with some inclusion of wind variations owing to the interaction between sea and land. The predicted wind direction at the location of the weather station captured an important change of the sea/land breeze of the observed one. In the morning, both in summer and winter, complicated wind fields with low wind speeds resulted in high pollutant concentrations almost all over the area. On the other hand, in the afternoon, the wind field was rather uniform and the terrain effects were not significant even in the mountainous area with the development of a mixing layer.

Increase in airway hyperresponsiveness among workers exposed to methylene diphenyldiisocyanate compared to workers exposed to toluene diisocyanate at a petrochemical plant in Korea.

The purpose of this study was to investigate the prevalence of airway hyperresponsiveness induced by methylene diphenyldiisocyanate (MDI) and toluene diisocyanate (TDI) at a petrochemical industry complex in Korea. Questionnaires, allergic skin test, and nonspecific airway hyperresponsiveness (AHR) were studied in 64 exposed workers and 27 control subjects. Questionnaires included questions about symptoms of cough, wheezing, chest tightness, dyspnea, rhinorrhea, sneezing, itching, stuffiness, tearing, urticaria, sore throat, and exacerbating time. Methacholine challenge tests were done. Bronchial responsiveness (BRindex) defined as log (% fall in FEV(1))/log (last concentration of methacholine +10). Prevalence of AHR (PC20 FEV(1) < 16.0 mg/mL of methacholine) was higher in MDI-exposed workers than in TDI-exposed workers [4/20 (20%) vs. 2/42 (4.7%), P<0.05]. Twenty-three workers (36%) of all subjects had respiratory symptoms. MDI-exposed workers, in comparison with control subjects, had higher BRindex (0.73+/-0.04 vs. 0.62+/-0.02, P<0.05). Workers exposed to TDI or MDI who had respiratory symptoms (n = 23), in comparison to workers exposed to TDI or MDI without respiratory symptoms (n = 41), had significantly higher BRindex (0.82+/-0.06 vs. 0.60+/-0.02, P<0.05). FEV(1) was significantly negatively correlated with BRindex (r = -0.253, P<0.05). BRindex was not correlated with atopy, smoking status, and exposure duration. These findings suggest that workers exposed to MDI are at a higher risk of asthma in comparison with TDI-exposed workers and control subjects at a petrochemical plant in Korea.

Respiratory and Irritant Health Effects of a Population Living in a Petrochemical-Polluted Area in Taiwan

Reported herewith are the results from an ongoing study of outdoor air pollution and the health of persons living in the communities in close proximity to petrochemical industrial complexes. To determine if there is an excess of adverse health outcomes in the population exposed to petrochemical industrial emissions, a health survey was undertaken in 1996 in this area and in one reference area which has no local industrial emissions. The subjects were 436 adults (30–64 years of age) living in the Sanwei area (exposed area) and 488 in Taicei (reference area). For several indicators of respiratory health, including cough, wheezing, and chronic bronchitis, the prevalence rates were not significantly different between the study and the control populations. Acute irritative symptoms (eye irritation, nausea, throat irritation, and chemical odor perception) were significantly more common in the exposed area, particularly perception of chemical odors (84.6% vs 2.1%). It is concluded that exposure to petrochemical air emissions may be associated with increased rates of acute irritative symptoms. Future studies are needed to identify the potential role of petrochemical industrial emissions (particularly volatile organic compounds) in the genesis of acute irritative symptoms in a nearby petrochemical industrial area.

Changes in Tree Ring Width and Density of Pinus thunbergii Growing in the Vicinity of Industrial Complex in Korea

There has been a decline in tree growth since the operation of factories at Pinus thunbergii forests around a petrochemical industrial complex in Korea. This study was carried out to investigate the effects of air pollution on tree ring width and ring density of Pinus thunbergii. Soft X-ray densitometrical method was used. Decline of ring width was the highest during 3 years immediately after the operation of factories. The percentage of decrease was almost bigger immediately after operation as compared with before. Maximum density (MAXD), and the difference (DD) between maximum density and minimum density (MIND) generally decreased since operation of factories, while minimum density increased in the beginning of operation of factories. There was a significant correlation between ring width and high temperature, and precipitation in the beginning of growing season, respectively. There was also a negative correlation between annual mean concentration of SO2 and ring width at 5% level (r=−0.627*). It is suggested that the decline of ring width after operation of factories was due to compound factors of air pollution and climate. The effect of other factors should be still more studied.

Characteristics of suspended particular matter in the vicinity of a petrochemical industry complex

Characteristics of suspended particular matter in the vicinity of a petrochemical industry complex