Time filter

Source Type

Lai T.M.,Sejong University | Lee W.,Sejong University | Hur J.,Sejong University | Kim Y.,Andong National University | And 4 more authors.
Water, Air, and Soil Pollution | Year: 2013

The influence of sediment grain size and land use was examined on the distribution of Cr, Ni, Zn, Pb, Cd, Cu, As, and Hg in the sediments collected from 19 subbasins of the Han River Basin, Korea. The degree of anthropogenic pollution of the heavy metals was also evaluated using the enrichment factor and geoaccumulation index based on local geochemical background concentrations. Except for Zn and Al, all the metals investigated showed significant correlations with the fine silt fraction of the sediments, suggesting that grain size distribution may contribute to the enrichment of the metals. Close association of the metal concentrations with a percentage of urban area in the subbasin was exhibited only for Cd, Cu, Hg, and Pb. The two pollution indices revealed that most of the sediments could be classified into a category of "unpolluted to moderately polluted," except for a subbasin with the highest percentage of urban area, which was highly polluted with Cu, Hg, and Pb. No relationship was observed between agricultural land use and the enrichment of metals. Principal component analysis showed that a combination of grain size distribution and percent urban area were responsible for 55 % of the variance of the metal distribution. Cluster analysis revealed that the sources of As might be different from the other metals. Multiple regression analyses based on fine silt fraction and percent urban area resulted in a good estimation of the concentrations of Cd, Cu, Hg, and Pb (r > 0.7, p < 0.005). © 2013 Springer Science+Business Media Dordrecht. Source

He W.,Sejong University | Jung H.,Sejong University | Lee J.-H.,NEO Environmental Business Corporation | Hur J.,Sejong University
Science of the Total Environment | Year: 2016

In this study, we examined the distribution behavior of sediment organic matter (SOM) between dissolved and particulate phases and the potential influencing factors by comparing the spectroscopic features of pore water organic matter (PWOM) and alkaline-extractable organic matter (AEOM) of river sediments. The characteristics of SOM were described by several selected spectral indicators and fluorescence excitation emission matrix (EEM)-parallel factor analysis (PARAFAC). The spectral indicators showed that larger sized SOM molecules with a higher aromatic content were more enriched in sediment particles than in pore water. The relative ratios of humification index between dissolved and particulate phases revealed that the SOM constituents with a higher degree of structural condensation were preferentially distributed onto sediment particles. EEM-PARAFAC demonstrated different distribution behaviors of protein-like (tyrosine-like and tryptophan-like) and humic-like substances in sediments. The relative abundance of tyrosine-like component was much higher in PWOM than in AEOM, whereas the other three components tended to be more abundant in AEOM. The predominant presence of tyrosine-like component suggests its potential operation as a discriminant indicator between PWOM and AEOM. Spearman correlations and non-metric multidimensional scaling further revealed that distribution of protein-like components onto sediment particles might be associated with reductive environments, aluminum minerals, and anthropogenic activities of upstream watersheds. This study demonstrated a successful application of using EEM-PARAFAC to examine the distribution behavior of different SOM constitutes between dissolved and solid phases. © 2015 Elsevier B.V. Source

Chen M.,Sejong University | Lee J.-H.,NEO Environmental Business Corporation | Hur J.,Sejong University
Environmental Science and Pollution Research | Year: 2015

Despite literature evidence suggesting the importance of sampling methods on the properties of sediment pore waters, their effects on the dissolved organic matter (PW-DOM) have been unexplored to date. Here, we compared the effects of two commonly used sampling methods (i.e., centrifuge and Rhizon sampler) on the characteristics of PW-DOM for the first time. The bulk dissolved organic carbon (DOC), ultraviolet-visible (UV-Vis) absorption, and excitation-emission matrixes coupled with parallel factor analysis (EEM-PARAFAC) of the PW-DOM samples were compared for the two sampling methods with the sediments from minimal to severely contaminated sites. The centrifuged samples were found to have higher average values of DOC, UV absorption, and protein-like EEM-PARAFAC components. The samples collected with the Rhizon sampler, however, exhibited generally more humified characteristics than the centrifuged ones, implying a preferential collection of PW-DOM with respect to the sampling methods. Furthermore, the differences between the two sampling methods seem more pronounced in relatively more polluted sites. Our observations were possibly explained by either the filtration effect resulting from the smaller pore size of the Rhizon sampler or the desorption of DOM molecules loosely bound to minerals during centrifugation, or both. Our study suggests that consistent use of one sampling method is crucial for PW-DOM studies and also that caution should be taken in the comparison of data collected with different sampling methods. © 2015, Springer-Verlag Berlin Heidelberg. Source

He W.,Sejong University | Lee J.-H.,NEO Environmental Business Corporation | Hur J.,Sejong University
Chemosphere | Year: 2016

Sediment organic matter (SOM) was extracted in an alkaline solution from 43 stream sediments in order to explore the anthropogenic signatures. The SOM spectroscopic characteristics including excitation-emission matrix (EEM)-parallel factor analysis (PARAFAC) were compared for five sampling site groups classified by the anthropogenic variables of land use, population density, the loadings of organics and nutrients, and metal enrichment. The conventional spectroscopic characteristics including specific UV absorbance, absorbance ratio, and humification index did not properly discriminate among the different cluster groups except in the case of metal enrichment. Of the four decomposed PARAFAC components, humic-like and tryptophan-like fluorescence responded negatively and positively, respectively, to increasing degrees of the anthropogenic variables except for land use. The anthropogenic enrichment of heavy metals was positively associated with the abundance of tryptophan-like component. In contrast, humic-like component, known to be mostly responsible for metal binding, exhibited a decreasing trend corresponding with metal enrichment. These conflicting trends can be attributed to the overwhelmed effects of the coupled discharges of heavy metals and organic pollutants into sediments. Our study suggests that the PARAFAC components can be used as functional signatures to probe the anthropogenic influences on sediments. © 2016 Elsevier Ltd. Source

Lee J.,University of Aarhus | Lee J.-H.,NEO Environmental Business Corporation | Kim C.-K.,NEO Environmental Business Corporation | Thomsen M.,University of Aarhus
Environment International | Year: 2014

In this paper, the cumulative risks of Di(2-ethylhexyl) phthalate (DEHP), Di-n-butyl phthalate (DBP), and Benzyl-butyl phthalate (BBP) to 2-year-old children in two countries: one European (Denmark) and one Asian (South Korea) were compared. Denmark does not produce phthalates as a raw material, while Korea produces more than 0.4. million. tons of the three above-mentioned phthalates each year. First, a comparative review of the existing phthalate regulations in the two countries was performed. Next, the level of childhood phthalate exposure from environmental and food sources was estimated using an exposure scenario approach. Then, the scenario based exposure level was compared with back-calculated exposure levels based on biomonitored urinary phthalate metabolite concentrations. The result verifies the existence of varying territorial human background exposure levels and the gap between exposure estimations based on exposure modeling and biomonitoring data. Cumulative childhood risk levels in Denmark were lower than in Korea. For both countries, risk levels from back calculation were higher than those from scenario estimation. The median cumulative risk levels from scenario estimation and back calculation respectively were 0.24 and up to 0.5 in Denmark while 0.52 and up to 0.95 in Korea. Food and indoor dust were the main exposure sources for all three phthalates. In order to protect human health from cumulative risks of these phthalates, the exposure scenarios in existing regulations such as the EU REACH need to be strengthened. Moreover, based on the contributions from different exposure sources, national specific risk management tools need to be developed and strengthened, applying a systemic approach to promote sustainable material flows. © 2013 Elsevier Ltd. Source

Discover hidden collaborations