Studies of spatial and temporal distribution characteristics of TSP-bound trace metals in Seoul, Korea

Characteristics and potential human health hazards of charged aerosols generated by high-voltage power lines

We investigated the characteristics of charged aerosols produced by high-voltage power lines (HVPLs) to explore the effects on respiratory disease incidence among those who handle HVPLs. Charged aerosol currents and charged aerosol concentrations were measured over 24 h at 12 sites. Aerosol current effective levels were 2.7 times higher compared to exposed and control sites. This pattern of relative enhancement at exposed sites was seen consistently in all measurements and the difference was 1.7 higher at exposed sites. Correlation analysis among all important variables revealed strong positive correlations between currents and concentration, currents and magnetic field, humidity and concentration, and humidity and particles of 10 µm or less (PM₁₀), while negative correlations were observed between charged aerosol concentrations and wind velocity and between wind velocity and humidity. Estimated production of charged aerosols from HVPLs found that people who work with HVPLs are highly likely to be exposed to charged aerosols.

Comprehensive pulmonary metabolome responses to intratracheal instillation of airborne fine particulate matter in rats

Airborne fine particulate matter (PM2.5) has been closely related with a variety of lung diseases. Although some modes of action (e.g. oxidative stress, inflammations) have been proposed, but the pulmonary toxicological mechanism remains obscure. In this paper, in order to understand the comprehensive pulmonary response to PM2.5 stress, a non-targeted high-throughput metabolomics strategy was adopted to characterize the overall metabolic changes and relevant toxicological pathways. PM2.5 samples were collected from Tangshan, one of the most polluted cities in China. Adult male rats were treated with PM2.5 suspension once a week at the dose of 1mg/kg/week through intratracheal instillation in three months. Aqueous and organic metabolite extracts of the lung tissues were subjected to metabolomics analysis using ultra-high performance liquid chromatograph/mass spectrometry. Along with a significant increase of oxidative stress, significant metabolome alterations were observed in the lung tissues of the treated rats. Nineteen metabolites were found decreased and 31 metabolites increased, which are mainly involved in lipid and nucleotide metabolism. Integrated pathway analysis suggests that PM2.5 can induce pulmonary toxicity through disturbing pro-oxidant/antioxidant balance, which may further correlate with metabolism changes of phospholipid, glycerophospholipid, sphingolipid and purine. These findings improve our understanding of the toxicological pathways of PM2.5 exposure.

Airborne iron across major urban centers in South Korea between 1991 and 2012

In this study, the distribution of airborne iron (Fe), one of the most abundant heavy metals in the Earth's crust was investigated to describe the basic features of i'ts pollution in various urban locations. The spatiotemporal distribution of Fe concentrations in seven major South Korean cities exhibited unique patterns to reflect differences as to Fe sources reflected in the relative enrichment in coastal relative to inland areas. In addition, the analysis of long-term trends of different metal species indicated that Fe levels maintained a fairly constant trend, while there had been a noticeable decline in concentrations of other metals (Cd, Cr, Cu, Mn, and Ni). The relative robustness of our correlation analysis was assessed by comparing (1) the Fe concentrations among cities, and (2) Fe with other metals at a given city. Fe concentrations were also partly explainable by the frequency of Asian dust events in most cities, with the observed spatial gradients in such relationships.

Natural and anthropogenic influences on heavy metals in airborne particles over the Korean Peninsula

Six monitoring stations were selected to characterize the variations in airborne concentrations of heavy metals in South Korea between 1999 and 2012. Three stations represented higher concentrations, and three represented lower concentrations. The heavy metals monitored at these stations include cadmium, chromium, copper, iron (Fe), lead, manganese (Mn), and nickel. During the study period, concentrations of heavy metals at many stations, including those around the Seoul metropolitan area, showed a decreasing trend. However, concentrations of Mn and Fe that are primarily of crustal origin increased at four of the six stations. Some stations were significantly affected by emissions from the local industrial complex (IC), and heavy metal concentrations at those stations were relatively high even in summer. Many heavy metal concentrations were higher in spring than in winter, but wintertime concentrations of Cr and Pb were higher at the stations representing lower concentrations due to the dominant influence of combustion emissions. At stations less affected by emissions from the IC, concentrations of Fe and Mn that are predominantly crustal in origin were higher in spring, when Asian dust (AD) events are most frequent. Although Mn concentrations were also high at stations within the steelmaking IC during AD periods, they were much higher during non-AD periods due to local emissions. Variations in heavy metal concentrations, which are heavily influenced by emissions from the IC, warrant individual analysis because their emission characteristics differ from those of typical cases.

Removal of particulate matter in a tubular wet electrostatic precipitator using a water collection electrode

As one of the effective control devices of air pollutants, the wet electrostatic precipitator (ESP) is an effective technique to eliminate acid mist and fine particles that are re-entrained in a collection electrode. However, its collection efficiency can deteriorate, as its operation is subject to water-induced corrosion of the collection electrode. To overcome this drawback, we modified the wet ESP system with the installation of a PVC dust precipitator wherein water is supplied as a replacement of the collection electrode. With this modification, we were able to construct a compact wet ESP with a small specific collection area (SCA, 0.83 m(2)/(m(3)/min)) that can acquire a high collection efficiency of fine particles (99.7%).

Metallic species in ambient particulate matter at rural and urban location of Delhi

In the present study 14 metallic species (six crustal and eight trace metals) were quantified in the suspended particulate matter (SPM) at a rural and urban location of Delhi, India. Particulate matter was collected on glass fiber filters for a period of one year (from September 2003 to August 2004). Rank sum test revealed that the TSP concentration at the urban site was significantly (P=0.47) higher as compared to the rural site. Urban site showed highest SPM concentration during winter while rural site during summer. Enrichment factor (EF) and coefficient of variation (CV) were calculated to assess the variability of elemental concentration data. Trace metals viz. Pb, Cd, Cu and Zn were observed to be highly enriched at both the sites, but EF for Zn and Cu was 2-3 times higher at the urban site as compared to the rural site. Trace and crustal metal concentration displayed less variability at the urban site. In the urban area, metals were mainly found to come from construction and industrial activities in surrounding. At the rural site, re-suspended and wind-blown dust appeared to be the source of observed elemental concentration.

An analysis of long-term changes in airborne toxic metals in South Korea's two largest cities from 1991 to 2004

BACKGROUND, AIM, AND SCOPE

Investigations on the temporal variabilities of metals generally show that the concentration levels of many harmful metals in air have been continuously decreasing around the world including North America and Western Europe. However, an excursion from such trends has been expected and demonstrated from E. Asia due to the major source contribution from China. To help understand long-term patterns of airborne toxic metals in East Asia, the particle-bound concentrations of Pb, Mn, Ni, Cr, and Cd were analyzed in the two largest cities of Korea, Seoul and Busan, over a 14-year period (1991 through 2004). The results of this study will provide a comprehensive overview on long-term trends of important metals in major urban areas of E. Asia.

MATERIALS AND METHODS

This study was conducted to investigate the environmental behavior and long-term trends of toxic metals in Seoul and Busan, the two most populated cities of Korea, from 1991 to 2004. To this end, the concentrations of five toxic metals (including Pb, Cd, Cr, Mn, and Ni) in TSP (total suspended particle) fractions were measured by atomic absorption spectrometry. The analysis of long-term patterns of metal concentration data was conducted using two different temporal grouping criteria for both the full study period (1991-2004) and the second half (1998-2004). The statistical significance of such variabilities was assessed through a comparison with relevant reference data from other areas of the world.

RESULTS

The annual mean concentration of the metals from the two cities was generally characterized by the lowest Cd (1.7-9.1 ng m(-3)) and largest Pb (51-341 ng m(-3)). The relative ordering of metal concentration levels from both cities was consistently found as: Pb > Mn > Ni > Cr > Cd. An evaluation of the absolute concentration levels showed that the values derived for both cities generally fell in an intermediate range between highly polluted (e.g., major Chinese cities) and moderately clean urban environments (Japanese or US sites).

DISCUSSION

To help describe the long-term patterns of each metal, the metal concentration data between the two cities were compared in a number of respects. The results show strong compatibility with respect to relative trends between Seoul and Busan. When the long-term trends are compared for the entire study period (1991-2004), most metals tend to experience reductions in their concentrations through the years (with an exception of Cr), regardless of the city. The patterns were so distinctive that the statistical significance of this decline, if compared by the magnitude of probability in the regression analysis, generally increased in the order: Mn < Cd < Ni < Pb. A more detailed analysis of the temporal patterns (i.e., the second half of the study period (period II): 1998-2004), however, indicates that some metals reversed their trend to an increasing direction. For instance, Ni and Cr (both cities) and Mn (Seoul) showed an annual rate of change (ARC) in the range of 5.57 to 11.5%. However, others consistently maintained a declining trend with ARC values of -1.55 (Cd at Seoul) to -12.2% (Pb at Busan).

CONCLUSIONS

According to the analysis of the long-term trend of trace metals, the efficiency of emission control appears to be highly complicated, as its effect is visualized to a certain extent. The patterns investigated in the two largest cities in Korea over a decadal period show that the reduction in concentration levels has been the most prominent and consistent for Pb but the least effective for Cr. Comparison among different studies and locations points out that changes in metal concentration levels, whether being an increase or decrease, should be tightly associated with the status of environmental pollution in the targeted area.

RECOMMENDATIONS AND PERSPECTIVES

Evaluation of long-term monitoring data for toxic metals is helpful to judge various factors involved in regulation efforts and the response of those target pollutants. Future efforts are desirable to develop methods that allow a comparison of measurement data between the particle-filtrated samples and time-integrated environmental archives (bioaccumulation). Such efforts can provide the descriptive basis for explaining the environmental behavior of toxic metals at various time scales.

Cadmium, diabetes and chronic kidney disease

Recent epidemiological studies suggest a positive association between exposure to the environmental pollutant cadmium (Cd) and the incidence and severity of diabetes. In this review, we examine the literature suggesting a relationship between Cd exposure, elevated blood glucose levels, and the development of diabetes. In addition we review human and animal studies indicating that Cd potentiates or exacerbates diabetic nephropathy. We also review the various possible cellular mechanisms by which Cd may alter blood glucose levels. In addition, we present some novel findings from our own laboratories showing that Cd elevates fasting blood glucose levels in an animal model of subchronic Cd exposure before overt signs of renal dysfunction are evident. These studies also show that Cd reduces insulin levels and has direct cytotoxic effects on the pancreas. Together, these findings indicate that Cd may be a factor in the development of some types of diabetes and they raise the possibility that Cd and diabetes-related hyperglycemia may act synergistically to damage the kidney.