A comparative study on per capita waste generation according to a waste collecting system in Korea

As cities are becoming increasingly aware of problems related to conventional mobile collection systems, automated pipeline-based vacuum collection (AVAC) systems have been introduced in some densely populated urban areas. The reasons are that in addition to cost savings, AVAC systems can be efficient, hygienic, and environmentally friendly. Despite difficulties in making direct comparisons of municipal waste between a conventional mobile collection system and an AVAC system, it is meaningful to measure the quantities in each of these collection methods either in total or on a per capita generation of waste (PCGW, g/(day*capita)) basis. Thus, the aim of this study was to assess the difference in per capita generation of household waste according to the different waste collection methods in Korea. Observations on household waste show that there were considerable differences according to waste collection methods. The value of per capita generation of food waste (PCGF) indicates that a person in a city using AVAC produces 60 % of PCGF (109.58 g/(day*capita)), on average, compared with that of a truck system (173.10 g/(day*capita)) as well as 23 %p less moisture component than that with trucks. The value of per capita generation of general waste (PCGG) in a city with an AVAC system showed 147.73 g/(day*capita), which is 20 % less than that with trucks delivered (185 g/(day*capita)). However, general waste sampled from AVAC showed a 35 %p increased moisture content versus truck delivery.     

Biodegradability of algal-derived organic matter in a large artificial lake by using stable isotope tracers

In order to understand the biodegradability of algal-derived organic matter, biodegradation experiments were conducted with ¹³C and ¹⁵N-labeled natural phytoplankton and periphytic algal populations in experimental conditions for 60 days. Qualitative changes in the dissolved organic matter were also determined using parallel factor analysis and the stable carbon isotopic composition of the hydrophobic dissolved organic matter through the experimental period. Although algal-derived organic matter is considered to be easily biodegradable, the initial amounts of total organic carbon newly produced by phytoplankton and periphytic algae remained approximately 16 and 44 % after 60 days, respectively, and about 22 and 43 % of newly produced particulate nitrogen remained. Further, the dissolved organic carbon derived from both algal populations increased significantly after 60 days. Although the dissolved organic matter gradually became refractory, the contributions of the algal-derived organic matter to the dissolved organic matter and hydrophobic dissolved organic matter increased. Our laboratory experimental results suggest that algal-derived organic matter produced by phytoplankton and periphytic algae could contribute significantly to the non-biodegradable organic matter through microbial transformations.     

The comparison of fossil carbon fraction and greenhouse gas emissions through an analysis of exhaust gases from urban solid waste incineration facilities

In this study, in order to understand accurate calculation of greenhouse gas emissions of urban solid waste incineration facilities, which are major waste incineration facilities, and problems likely to occur at this time, emissions were calculated by classifying calculation methods into 3 types. For the comparison of calculation methods, the waste characteristics ratio, dry substance content by waste characteristics, carbon content in dry substance, and ¹²C content were analyzed; and in particular, CO₂ concentration in incineration gases and ¹²C content were analyzed together. In this study, 3 types of calculation methods were made through the assay value, and by using each calculation method, emissions of urban solid waste incineration facilities were calculated then compared. As a result of comparison, with Calculation Method A, which used the default value as presented in the IPCC guidelines, greenhouse gas emissions were calculated for the urban solid waste incineration facilities A and B at 244.43 ton CO₂/day and 322.09 ton CO₂/day, respectively. Hence, it showed a lot of difference from Calculation Methods B and C, which used the assay value of this study. It is determined that this was because the default value as presented in IPCC, as the world average value, could not reflect the characteristics of urban solid waste incineration facilities. Calculation Method B indicated 163.31 ton CO₂/day and 230.34 ton CO₂/day respectively for the urban solid waste incineration facilities A and B; also, Calculation Method C indicated 151.79 ton CO₂/day and 218.99 ton CO₂/day, respectively.

Implications: This study intends to compare greenhouse gas emissions calculated using ¹²C content default value provided by the IPCC (Intergovernmental Panel on Climate Change) with greenhouse gas emissions calculated using ¹²C content and waste assay value that can reflect the characteristics of the target urban solid waste incineration facilities. Also, the concentration and ¹²C content were calculated by directly collecting incineration gases of the target urban solid waste incineration facilities, and greenhouse gas emissions of the target urban solid waste incineration facilities through this survey were compared with greenhouse gas emissions, which used the previously calculated assay value of solid waste.     

Comprehensive Environmental Investigation at Former Industrial/Petroleum Underground Storage Tank Sites in Long Beach,CA: A Forensic Perspective

Two industrial sites were investigated based on years of available hydrogeologic information and monitoring data for soil and groundwater. Collected data were forensically evaluated using age-dating and fingerprinting methods. The previous business uses of the project sites were as a gas station, laundry/dry-cleaning service, and car wash with petroleum underground storage tanks (USTs). As a result, these sites were exposed to a number of toxic contaminants at relatively high concentrations. Source control was necessary for successful remediation and the ultimate removal of the remaining compounds from these industrial sites. Although contaminated soil around the source was excavated during the remedial action and the high concentrations of contaminants were reduced, typical groundwater contaminants such as petroleum hydrocarbons as gasoline (TPH-G), benzene, toluene, ethylbenzene, xylenes (BTEX), and oxygenates including methyl tert-butyl ether (MTBE), diisopropyl ether (DIPE), ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), and tert-butyl alcohol (TBA) were persistently found at the studied sites around the source points. The plume and concentration of contaminants had changed their shapes and strength for all monitoring periods. Thus, additional source control seems to be a requirement for the complete removal of source contamination, which must be ascertained with groundwater and soil monitoring on a regular time base. For the study sites, monitored natural attenuation was relatively feasible for the long-term plan; however, it did not offer a perfect remediation solution for an ultimate goal because of residual toxic compounds that might have affected the surrounding residential areas at higher concentrations than their health limits. Therefore, as a remediation strategy, the combination of clean-up technology and natural attenuation with monitoring activities are more highly recommended than either clean-up or natural attenuation used separately.     

Congener-specific accumulation and environmental risk assessment of polybrominated diphenyl ethers in diverse Korean sewage sludge types

Industrial, domestic wastewater, and livestock sludge samples were collected from 23 wastewater treatment plants in Korea and analyzed for polybrominated diphenyl ethers (PBDEs). The concentrations of Σ₁₉PBDE ranged from 4.01 to 10,400 ng/g dry weight. The average Σ₁₉PBDE concentrations in industrial, domestic wastewater, and livestock sludge were 1,560?±?3,610, 402?±?148, and 27.6?±?50.4 ng/g dry weight, respectively. The composition of PBDEs differed according to the type of sludge. Among the PBDE congeners, BDE 209 was dominant in all sludge samples. After BDE 209, relatively high levels were found for BDE 28 and 47 from industrial sludge, BDE 47 and 99 from domestic wastewater sludge, and BDE 206, 207, and 208 from livestock sludge. Using hierarchical cluster analysis, sludges were divided into three groups according to PBDE congener composition. A risk assessment of PBDEs in sludge used for soil amendment was carried out. Preliminary results indicated that the potential risk of soil exposed to PBDEs in sludge was relatively low.     

Sources of Fine Particulate Species in Ambient Air over Lake Champlain Basin,VT

Abstract

This study is a part of an ongoing investigation of the types and locations of emission sources that contribute fine particulate air contaminants to Underhill, VT. The air quality monitoring data used for this study are from the Interagency Monitoring of Protected Visual Environments network for the period of 2001–2003 for the Underhill site. The main source-receptor modeling techniques used are the positive matrix factorization (PMF) and potential source contribution function (PSCF). This new study is intended as a comparison to a previous study of the 1988–1995 Underhill data that successfully revealed a total of 11 types of emission sources with significant contributions to this rural site. This new study has identified a total of nine sources: nitrate-rich secondary aerosol, wood smoke, East Coast oil combustion, automobile emission, metal working, soil/dust, sulfur-rich aerosol type I, sulfur-rich aerosol type II, and sea salt/road salt. Furthermore, the mass contributions from the PMF identified sources that correspond with sampling days with either good or poor visibility were analyzed to seek possible correlations. It has been shown that sulfur-rich aerosol type I, nitrate aerosol, and automobile emission are the most important contributors to visibility degradation. Soil/dust and sea salt/road salt also have an added effect.     

Chemical Dynamics of Clouds at Mt. Mitchell,North Carolina

The role of clouds as the primary pathway for deposition of air pollutants into ecosystems has recently acquired much attention. Moreover, the acidity of clouds is highly variable over short periods of time. Cloud water collections were made at Mt. Mitchell State Park, North Carolina, using a real-time cloud and rain acidity/ conductivity (CRAC) analyzer during May to September 1987, 1988 and 1989 in an effort to explore extremes of chemical exposure. On the average, the mountain peak was exposed to cloud episodes about 70 percent of experimental days. The lowest pH of cloud water in nearly real-time (～10 min.) samples was 2.4, while that in hourly integrated samples was 2.6. The cloud pH during short cloud events (mean pH 3.1), whjch results from the orographic lifting mechanism, was lower than that during long cloud events (mean pH 3.5), which are associated with mesoscale or synoptic atmospheric disturbances. On the average, the pH values in nonprecipitating cloud events were about 0.4 pH unit lower than those in precipitating cloud events. Sulfate, nitrate, ammonium and hydrogen ions were found to be the major constituents of cloud water, and these accounted for -90 percent of the ionic concentration. Total ionic concentrations were found to be much higher in non-precipitating clouds (670-3,010 μeq/L) than those in precipitating clouds (220-370 μeq/L). At low acidity, ionic balance is sometimes not obtained. It is suggested that organic acids may provide this balance.

The profile of cloud water ionic concentration versus time was frequently observed to show decrease at the beginning and rising toward the end during short cloud events. Before the dissipation of clouds, a decrease in cloud water pH and an increase in ionic concentration were found. At the same time, temperature and solar radiation increased, and relative humidity and microphysical parameters (liquid water content, average droplet size, and droplet concentration) decreased. These observations suggest that evaporative dissipation of cloud droplets leads to acidification of cloud water. Mean pH of cloud water was 3.4 when the prevailing wind was from the northwest direction, and it was 3.9 when the wind was from the west direction. The effects of variations in cloud liquid water content have been separated from variations in pre-cloud pollutant concentrations to determine the relationship between source intensity and cloud water concentrations.     

A real-time monitoring and assessment method for calculation of total amounts of indoor air pollutants emitted in subway stations

Subway systems are considered as main public transportation facility in developed countries. Time spent by people in indoors, such as underground spaces, subway stations, and indoor buildings, has gradually increased in the recent past. Especially, operators or old persons who stay in indoor environments more than 15 hr per day usually influenced a greater extent by indoor air pollutants. Hence, regulations on indoor air pollutants are needed to ensure good health of people. Therefore, in this study, a new cumulative calculation method for the estimation of total amounts of indoor air pollutants emitted inside the subway station is proposed by taking cumulative amounts of indoor air pollutants based on integration concept. Minimum concentration of individual air pollutants which naturally exist in indoor space is referred as base concentration of air pollutants and can be found from the data collected. After subtracting the value of base concentration from data point of each data set of indoor air pollutant, the primary quantity of emitted air pollutant is calculated. After integration is carried out with these values, adding the base concentration to the integration quantity gives the total amount of indoor air pollutant emitted. Moreover, the values of new index for cumulative indoor air quality obtained for 1 day are calculated using the values of cumulative air quality index (CAI). Cumulative comprehensive indoor air quality index (CCIAI) is also proposed to compare the values of cumulative concentrations of indoor air pollutants. From the results, it is clear that the cumulative assessment approach of indoor air quality (IAQ) is useful for monitoring the values of total amounts of indoor air pollutants emitted, in case of exposure to indoor air pollutants for a long time. Also, the values of CCIAI are influenced more by the values of concentration of NO₂, which is released due to the use of air conditioners and combustion of the fuel. The results obtained in this study confirm that the proposed method can be applied to monitor total amounts of indoor air pollutants emitted, inside apartments and hospitals as well.

Implications: Nowadays, subway systems are considered as main public transportation facility in developed countries. Time spent by people in indoors, such as underground spaces, subway stations, and indoor buildings, has gradually increased in the recent past. Especially, operators or old persons who stay in the indoor environments more than 15 hr per day usually influenced a greater extent by indoor air pollutants. Hence, regulations on indoor air pollutants are needed to ensure good health of people. Therefore, this paper presents a new methodology for monitoring and assessing total amounts of indoor air pollutants emitted inside underground spaces and subway stations. A new methodology for the calculation of cumulative amounts of indoor air pollutants based on integration concept is proposed. The results suggest that the cumulative assessment approach of IAQ is useful for monitoring the values of total amounts of indoor air pollutants, if indoor air pollutants accumulated for a long time, especially NO₂ pollutants. The results obtained here confirm that the proposed method can be applied to monitor total amounts of indoor air pollutants emitted, inside apartments and hospitals as well.     

Dietary assessment of human exposure to PBDEs in South Korea

This study was conducted to measure the concentration of PBDEs in various food stuffs from Korea and to estimate levels of PBDE intake from food for the Korean population according to geographical location and age. 20 types of food samples were collected from four heavily populated cities (Seoul, Gwangju, Daejeon, Pusan) and one rural city (Gangneung) and were analyzed for 19 polybrominated diphenyl ether congeners (BDE 15, 17, 28, 33, 47, 49, 66, 71, 85, 99, 100, 119, 126, 138, 153, 154, 183, and 209).No significant differences in total PBDE levels in foods were found among four large cities (Gwangju; 10.91 ng g^?1 wet weight (ww), Seoul; 7.66 ng g^?1 ww, Daejeon; 6.91 ng g^?1 ww, Pusan; 6.87 ng g^?1 ww) and one rural city (Gangneung; 8.72 ng g^?1 ww). Daily dietary intake of PBDEs does not appear to be related to the extent of urbanization.Total dietary intake of PBDE for the average general population was 72.30 ng d^?1 (not detected (ND) = 0) which was similar to other countries. In all food groups, the largest contribution to PBDE intake was from fish and shellfish (48.96 ng d^?1). Total PBDE consumed per kilogram of body weight was estimated to range from 2.70 ng kg^?1 d^?1 for infants 1 through 2 years of age to 0.85 ng kg^?1 d for 65 years and older and was highest in young children and decreased with increasing age.     

Distribution features of biological hazardous pollutants in residential environments in Korea

This research has been conducted continuously since 2009 as part of a cohort of studies examining relationships between asthma and genetic factors, dietary habits, and environmental factors. Based on data from environmental research on house dust mites and endotoxins, which are widely known as pollutants in bedding that cause asthma in pregnant women and children, this work was conducted to obtain basic data that can be used in future cohort studies that analyze links between distribution of biological hazards and physical features of residential environments. The detection rates of house dust mite allergens, Der p1 and Der f1, were 52.7 and 86.5 %, respectively, indicating that Der f1 is a dominant species in domestic indoor environments. According to comparisons between concentrations of house dust mites and endotoxins in bedding of pregnant women and children, Der p1 and endotoxins showed significantly lower concentrations in bedding of pregnant women compared with those in bedding of children, whereas Der f1 showed no significant difference in concentration according to bedding.