Seasonal evaluation of bioaerosols from indoor air of residential apartments within the metropolitan area in South Korea

The aims of the present study were to determine the levels of bioaerosols including airborne culturable bacteria (total suspended bacteria, Gram-positive bacteria, Staphylococcus, Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), and Gram-negative bacteria), fungi, endotoxin, and viruses (influenza A, influenza B, respiratory syncytial virus types A/B, parainfluenza virus types 1/2/3, metapnemovirus, and adenovirus) and their seasonal variations in indoor air of residential apartments. Of the total suspended bacteria cultured in an indoor environment, Staphylococcus was dominant and occupied 49.0 to 61.3 % of indoor air. Among Staphylococcus, S. aureus were detected in 100 % of households' indoor air ranging from 4 to 140 CFU/m³, and 66 % of households were positive for MRSA ranging from 2 to 80 CFU/m³. Staphylococcus and S. aureus concentrations correlated with indoor temperature (adjusted β: 0.4440 and 0.403, p?<?0.0001). Among respiratory viruses, adenovirus was detected in 14 (14 %) samples and influenza A virus was detected in 3 (3 %) samples regarding the indoor air of apartments. Adenovirus concentrations were generally higher in winter (mean concentration was 2,106 copies/m³) than in spring (mean concentration was 173 copies/m³), with concentrations ranging between 12 and 560 copies/m³. Also, a strong negative correlation between adenovirus concentrations and relative humidity in indoor air was observed (r?=??0.808, p?<?0.01). Furthermore, temperature also negatively correlated with adenovirus concentrations (r?=??0.559, p?<?0.05).     

Roles of SO2 oxidation in new particle formation events

The oxidation of SO₂ is commonly regarded as a major driver for new particle formation (NPF) in the atmosphere. In this study, we explored the connection between measured mixing ratio of SO₂ and observed long-term (duration > 3 hr) and short-term (duration < 1.5 hr) NPF events at a semi-urban site in Toronto. Apparent NPF rates (J₃₀) showed a moderate correlation with the concentration of sulfuric acid ([H₂SO₄]) calculated from the measured mixing ratio of SO₂ in long-term NPF events and some short-term NPF events (Category I) (R² = 0.66). The exponent in the fitting line of J₃₀ ~ [H₂SO₄]ⁿ in these events was 1.6. It was also found that SO₂ mixing ratios varied a lot during long-term NPF events, leading to a significant variation of new particle counts. In the SO₂-unexplained short-term NPF events (Category II), analysis showed that new particles were formed aloft and then mixed down to the ground level. Further calculation results showed that sulfuric acid oxidized from SO₂ probably made a negligible contribution to the growth of > 10 nm new particles.     

A comparison study of the potential risks induced in arable land and forest soils by carcass-derived pollutants

Environmental Geochemistry and Health - Improper decisions concerning animal carcass disposal sites pose grave threats to environmental biosecurity. However, only a few studies have focused on the...     

Observed chemical characteristics of long-range transported particles at a marine background site in Korea

Deokjeok Island is located off the west coast of the Korean Peninsula and is a suitable place to monitor the long-range transport of air pollutants from the Asian continent. In addition to pollutants, Asian dust particles are also transported to the island during long-range transport events. Episodic transport of dust and secondary particles was observed during intensive measurements in the spring (March 31-April 11) and fall (October 13-26) of 2009. In this study, the chemical characteristics of long-range-transported particles were investigated based on highly time-resolved ionic measurements with a particle-into-liquid system coupled with an online ion chromatograph (PILS-IC) that simultaneously measures concentrations of cations (Li+, Na , NH4+, K+, Ca2+, Mg2+) and anions (F-, C1-, NO3-, SO42-). The aerosol optical thickness (AOT) distribution retrieved by the modified Bremen Aerosol Retrieval (M-BAER) algorithm from moderate resolution imaging spectroradiometer (MODIS) satellite data confirmed the presence of a thick aerosol plume coming from the Asian continent towards the Korean peninsula. Seven distinctive events involving the long-range transport (LRT) of aerosols were identified and studied, the chemical components of which were strongly related to sector sources. Enrichment of acidic secondary aerosols on mineral dust particles, and even of sea-salt components, during transport was observed in this study. Backward trajectory, chemical analyses, and satellite aerosol retrievals identified two distinct events: a distinctively high [Ca2++Mg2]/[Na+] ratio (>2.0), which was indicative of a preprocessed mineral dust transport event, and a low [Ca2++Mg2+]/[Na+] ratio (<2.0), which was indicative of severe aging of sea-salt components on the processed dust particles. Particulate C1- was depleted by up to 85% in spring and 50% in the fall. A consistent fraction of carbonate replacement (FCR) averaged 0.53 in spring and 0.55 in the fall. Supporting evidences of C1- enrichment on the marine boundary layer prior to a dust front were also found. Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of the Air & Waste Management Association for sector and air mass classifications of clean and LRT cases.     

Derivation of site-specific surface water quality criteria for the protection of aquatic ecosystems near a Korean military training facility

This study suggested the first Korean site-specific ecological surface water quality criteria for the protection of ecosystems near an artillery range at a Korean military training facility. Surface water quality (SWQ) criteria in Korea address human health protection but do not encompass ecological criteria such as limits for metals and explosives. The first objective of this study was to derive site-specific SWQ criteria for the protection of aquatic ecosystems in Hantan River, Korea. The second objective was to establish discharge criteria for the artillery range to protect the aquatic ecosystems of Hantan River. In this study, we first identified aquatic organisms living in the Hantan River, including fishes, reptiles, invertebrates, phytoplankton, zooplankton, and amphibians. Second, we collected ecotoxicity data for these aquatic organisms and constructed an ecotoxicity database for Cd, Cu, Zn, TNT, and RDX. This study determined the ecological maximum permissible concentrations for metals and explosives based on the ecotoxicity database and suggested ecological surface water quality criteria for the Hantan River by considering analytical detection limits. Discharge limit criteria for the shooting range were determined based on the ecological surface water quality criteria suggested for Hantan River with further consideration of the dilution of the contaminants discharged into the river.     

Water quality guidelines for chemicals: learning lessons to deliver meaningful environmental metrics

Many jurisdictions around the globe have well-developed regulatory frameworks for the derivation and implementation of water quality guidelines (WQGs) or their equivalent (e.g. environmental quality standards, criteria, objectives or limits). However, a great many more still do not have such frameworks and are looking to introduce practical methods to manage chemical exposures in aquatic ecosystems. There is a potential opportunity for learning and sharing of data and information between experts from different jurisdictions in order to deliver efficient and effective methods to manage potential aquatic risks, including the considerable reduction in the need for aquatic toxicity testing and the rapid identification of common challenges. This paper reports the outputs of an international workshop with representatives from 14 countries held in Hong Kong in December 2011. The aim of the workshop and this paper was to identify ‘good practice’ in the development of WQGs to deliver to a range of environmental management goals. However, it is important to broaden this consideration to cover often overlooked facets of implementable WQGs, such as demonstrable field validation (i.e. does the WQG protect what it is supposed to?), fit for purpose of monitoring frameworks (often an on-going cost) and finally how are these monitoring data used to support management decisions in a manner that is transparent and understandable to stakeholders. It is clear that regulators and the regulated community have numerous pressures and constraints on their resources. Therefore, the final section of this paper addresses potential areas of collaboration and harmonisation. Such approaches could deliver a consistent foundation from which to assess potential chemical aquatic risks, including, for example, the adoption of bioavailability-based approaches for metals, whilst reducing administrative and technical burdens in jurisdictions.     

Electrochemical removal of nitrate using ZVI packed bed bipolar electrolytic cell

The present study investigates the performance of the zero valent iron (ZVI, Fe⁰) packed bed bipolar electrolytic cell for nitrate removal. The packing mixture consists of ZVI as electronically conducting material and silica sand as non-conducting material between main cathode and anode electrodes. In the continuous column experiments for the simulated groundwater (initial nitrate and electrical conductivity of about 30 mg L⁻¹ as N and 300 μS cm⁻¹, respectively), above 99% of nitrate was removed at the applied potential of 600 V with the main anode placed on the bottom of reactor. The influx nitrate was converted to ammonia (20% to maximum 60%) and nitrite (always less than 0.5 mg L⁻¹ as N in the effluent). The optimum packing ratio (v/v) of silica sand to ZVI was found to be 1:1-2:1. Magnetite was observed on the surface of the used ZVI as corrosion product. The reduction at the lower part of the reactor in acidic condition and adsorption at the upper part of the reactor in alkaline condition are the major mechanism of nitrate removal.     

Construction of a chemical ranking system of soil pollution substances for screening of priority soil contaminants in Korea

The Korean government recently proposed expanding the number of soil-quality standards to 30 by 2015. The objectives of our study were to construct a reasonable protocol for screening priority soil contaminants for inclusion in the planned soil quality standard expansion. The chemical ranking system of soil pollution substances (CROSS) was first developed to serve as an analytical tool in chemical scoring and ranking of possible soil pollution substances. CROSS incorporates important parameters commonly used in several previous chemical ranking and scoring systems and the new soil pollution parameters. CROSS uses soil-related parameters in its algorithm, including information related to the soil environment, such as soil ecotoxicological data, the soil toxic release inventory (TRI), and soil partitioning coefficients. Soil TRI and monitoring data were incorporated as local specific parameters. In addition, CROSS scores the transportability of chemicals in soil because soil contamination may result in groundwater contamination. Dermal toxicity was used in CROSS only to consider contact with soil. CROSS uses a certainty score to incorporate data uncertainty. CROSS scores the importance of each candidate substance and assigns rankings on the basis of total scores. Cadmium was the most highly ranked. Generally, metals were ranked higher than other substances. Pentachlorophenol, phenol, dieldrin, and methyl tert-butyl ether were ranked the highest among chlorinated compounds, aromatic compounds, pesticides, and others, respectively. The priority substance list generated from CROSS will be used in selecting substances for possible inclusion in the Korean soil quality standard expansion; it will also provide important information for designing a soil-environment management scheme.