The continuous monitoring of field water samples with a novel multi-channel two-stage mini-bioreactor system

Toxicity monitoring of field water samples was performed using a novel multi-channel two-stage mini-bioreactor system and genetically engineered bioluminescent bacteria for the continuous monitoring and classification of the toxicity present in the samples. The toxicity of various samples spiked with known endocrine disrupting chemicals and phenol was also investigated for system characterization. The field samples used in this study were obtained from two different sites on a monthly basis--from a drinking water treatment plant, referred to as site N, and from a stream near a dam which is currently being constructed, referred to as site T. These samples were either pumped or injected into the second mini-bioreactors to initiate the toxicity test. Most of the samples did not show any specific toxicity. However, one sample showed to have, based upon the detection results, and was deemed toxic. The samples spiked with phenol showed possible responses in the DPD2540 and TV1061 channels, indicating the occurrence of both membrane and protein damage due to phenol. In the tests using an endocrine disrupting chemical, bisphenol A, DNA damage was detected in the DPD2794 channel with a concentration of 2 ppm. Finally, a simple but novel early warning protocol that can be used in a drinking water reservoir and a suspected place where effluents of toxic materials enter the water sourse was suggested with a schematic diagram. In conclusion, this system showed good feasibility for use as a toxicity monitoring system in the field and as an early warning system, indicating if effluents are toxic.     

A multilevel study of group‐focused and individual‐focused transformational leadership,social exchange relationships,and performance in teams

Using matched reports from 73 team leaders and 359 of their members across 23 companies in Korea, we examined a multilevel model where group‐ and individual‐focused transformational leadership and their influence processes operate at the team and dyadic levels independently and interactively to be associated with team and member performance. Results indicated that group‐focused transformational leadership was positively associated with team performance through team member exchange (TMX), whereas individual‐focused transformational leadership positively related to team members' in‐role and extra‐role performance through leader–member exchange (LMX). TMX not only positively mediated the relationships between group‐focused transformational leadership and member performance after controlling for LMX but also positively moderated LMX–performance relationships. Moreover, the indirect effect of individual‐focused transformational leadership through LMX on member performance was contingent upon the level of TMX. Theoretical and applied implications are discussed. Copyright © 2015 John Wiley & Sons, Ltd.     

Degradation of hexane and other recalcitrant hydrocarbons by a novel isolate, <Emphasis Type="Italic">Rhodococcus</Emphasis> sp. EH831

Background, aim, and scope  

Hexane, a representative VOC, is used as a solvent for extraction and as an ingredient in gasoline. The degradation of hexane by bacteria is relatively slow due to its low solubility. Moreover, the biodegradation pathway of hexane under aerobic conditions remains to be investigated; therefore, a study relating to aerobic biodegradation mechanisms is required. Consequently, in this study, an effective hexane degrader was isolated and the biodegradation pathway examined for the first time. In addition, the degradation characteristics of a variety of recalcitrant hydrocarbons were qualitatively and quantitatively investigated using the isolate.     

Similarities and differences of metal distributions in the tissues of molluscs by using multivariate analyses

Multivariate analysis including correlation, multiple stepwise linear regression, and cluster analyses were applied to investigate the heavy metal concentrations (Cd, Cu, Fe, Ni, Pb, and Zn) in the different parts of bivalves and gastropods. It was also aimed to distinguish statistically the differences between the marine bivalves and the gastropods with regards to the accumulation of heavy metals in the different tissues. The different parts of four species of bivalves and four species of gastropods were obtained and analyzed for heavy metals. The multivariate analyses were then applied on the data. From the multivariate analyses conducted, there were correlations found between the soft tissues of bivalves and gastropods, but none was found between the shells and the soft tissues of most of the molluscs (except for Cerithidea obtusa and Puglina cochlidium). The significant correlations (P < 0.05) found between the soft tissues were further complemented by the multiple stepwise linear regressions where heavy metals in the total soft tissues were influenced by the accumulation in the different types of soft tissues. The present study found that the distributions of heavy metals in the different parts of molluscs were related to their feeding habits and living habitats. The statistical approaches proposed in this study are recommended for use in biomonitoring studies, since multivariate analyses can reduce the cost and time involved in identifying an effective tissue to monitor the heavy metal(s) bioavailability and contamination in tropical coastal waters.     

Assessment of airborne environmental bacteria and related factors in 25 underground railway stations in Seoul,Korea

This study assessed bacterial concentrations in indoor air at 25 underground railway stations in Seoul, Korea, and investigated various related factors including the presence of platform screen doors (PSD), depth of the station, year of construction, temperature, relative humidity, and number of passengers. A total of 72 aerosol samples were collected from all the stations. Concentrations of total airborne bacteria (TAB) ranged from not detected (ND) to 4997 CFU m^?3, with an overall geometric mean (GM) of 191 CFU m^?3. Airborne bacteria were detected at 23 stations (92%) and Gram-negative bacteria (GNB) were detected at two stations (8%). TAB concentrations of four stations (16%) exceeded 800 CFU m^?3, the Korea indoor bio-aerosol guideline. The results of the study showed that TAB concentrations at the stations without PSD showed higher TAB concentrations than those with PSD, though not at statistically significant levels. TAB concentrations of deeper stations revealed significantly higher levels than those of shallower stations. Based on this study, it is recommended that mitigation measures be applied to improve the indoor air quality (IAQ) of underground railway stations in Seoul, with focused attention on deeper stations.     

Effect of bioavailable arsenic fractions on the collembolan community in an old abandoned mine waste

Environmental Geochemistry and Health - Mine waste from abandoned mines poses a risk to soil ecosystems due to the dispersion of arsenic (As) in the mine waste to the nearby soil environment....     

Male-Specific and Somatic Coliphage Profiles from Major Aquaculture Areas in Republic of Korea

Human and animal feces are important sources of various types of microbial contamination in water. Especially, enteric viruses, the major agents of waterbo     

Application of constructed wetlands for wastewater treatment in tropical and subtropical regions (2000–2013)

Constructed wetlands (CWs) have been successfully used for treating various wastewaters for decades and have been identified as a sustainable wastewater management option for developing countries. With the goal of promoting sustainable engineered systems that support human well-being but are also compatible with sustaining natural (environmental) systems, the application of CWs has become more relevant. Such application is especially significant for developing countries with tropical climates, which are very conducive to higher biological activity and productivity, resulting in higher treatment efficiencies compared to those in temperate climates. This paper therefore highlights the practice, applications, and research of treatment wetlands under tropical and subtropical conditions since 2000. In the present review, removal of biochemical oxygen demand (BOD) and total suspended solid (TSS) was shown to be very efficient and consistent across all types of treatment wetlands. Hybrid systems appeared more efficient in the removal of total suspended solid (TSS) (91.3%), chemical oxygen demand (COD) (84.3%), and nitrogen (i.e., 80.7% for ammonium (NH)₄-N, 80.8% for nitrate (NO)₃-N, and 75.4% for total nitrogen (TN)) as compared to other wetland systems. Vertical subsurface flow (VSSF) CWs removed TSS (84.9%), BOD (87.6%), and nitrogen (i.e., 66.2% for NH₄-N, 73.3% for NO₃-N, and 53.3% for TN) more efficiently than horizontal subsurface flow (HSSF) CWs, while HSSF CWs (69.8%) showed better total phosphorus (TP) removal compared to VSSF CWs (60.1%). Floating treatment wetlands (FTWs) showed comparable removal efficiencies for BOD (70.7%), NH₄-N (63.6%), and TP (44.8%) to free water surface (FWS) CW systems.     

Application of constructed wetlands for wastewater treatment in tropical and subtropical regions (2000-2013)

Constructed wetlands(CWs) have been successfully used for treating various wastewaters for decades and have been identified as a sustainable wastewater management option for developing countries. With the goal of promoting sustainable engineered systems that support human well-being but are also compatible with sustaining natural(environmental)systems, the application of CWs has become more relevant. Such application is especially significant for developing countries with tropical climates, which are very conducive to higher biological activity and productivity, resulting in higher treatment efficiencies compared to those in temperate climates. This paper therefore highlights the practice,applications, and research of treatment wetlands under tropical and subtropical conditions since 2000. In the present review, removal of biochemical oxygen demand(BOD) and total suspended solid(TSS) was shown to be very efficient and consistent across all types of treatment wetlands. Hybrid systems appeared more efficient in the removal of total suspended solid(TSS)(91.3%), chemical oxygen demand(COD)(84.3%), and nitrogen(i.e.,80.7% for ammonium(NH)4-N, 80.8% for nitrate(NO)3-N, and 75.4% for total nitrogen(TN))as compared to other wetland systems. Vertical subsurface flow(VSSF) CWs removed TSS(84.9%), BOD(87.6%), and nitrogen(i.e., 66.2% for NH4-N, 73.3% for NO3-N, and 53.3% for TN)more efficiently than horizontal subsurface flow(HSSF) CWs, while HSSF CWs(69.8%)showed better total phosphorus(TP) removal compared to VSSF CWs(60.1%). Floating treatment wetlands(FTWs) showed comparable removal efficiencies for BOD(70.7%),NH4-N(63.6%), and TP(44.8%) to free water surface(FWS) CW systems.     

Passive flux meter measurement of water and nutrient flux in saturated porous media: bench-scale laboratory tests

The passive nutrient flux meter (PNFM) is introduced for simultaneous measurement of both water and nutrient flux through saturated porous media. The PNFM comprises a porous sorbent pre-equilibrated with a suite of alcohol tracers, which have different partitioning coefficients. Water flux was estimated based on the loss of loaded resident tracers during deployment, while nutrient flux was quantified based on the nutrient solute mass captured on the sorbent. An anionic resin, Lewatit 6328 A, was used as a permeable sorbent and phosphate (PO4(3-)) was the nutrient studied. The phosphate sorption capacity of the resin was measured in batch equilibration tests as 56 mg PO4(3-) g(-1), which was determined to be adequate capacity to retain PO4(3-) loads intercepted over typical PNFM deployment periods in most natural systems. The PNFM design was validated with bench-scale laboratory tests for a range of 9.8 to 28.3 cm d(-1) Darcy velocities and 6 to 43 h deployment durations. Nutrient and water fluxes measured by the PNFM averaged within 6 and 12% of the applied values, respectively, indicating that the PNFM shows promise as a tool for simultaneous measurement of water and nutrient fluxes.