Effects of BPA and DES on longchin goby (Chasmichthys dolichognathus) in vitro during the oocyte maturation

This study was performed in order to assess whether bisphenol (BPA) and diethylstilbestrol (DES) had agonistic or antagonistic effects on oocyte maturation using marine fish. We tested the effects of these chemicals on in vitro maturation, germinal vesicle breakdown (GVBD), assay using oocytes from the longchin goby, Chasmichthys dolichognathus. During the maturation process, low concentrations of BPA and DES triggered GVBD depending on the stage of oocyte development; BPA at 0.044 nM and DES at 0.037, 0.37, and 3.73 nM induced GVBD in 0.82-0.88 mm diameter oocytes (germinal vesicle located near the center of oocytes). In 0.76-0.80 mm diameter oocytes (fully vitellogenic oocytes), BPA induced GVBD at relatively higher concentrations (4.38, 43.8, and 438 nM). In 0.86-0.90 mm diameter oocytes, BPA and DES had no observable effect on GVBD at the concentrations tested. Oocytes with diameters between 0.82 and 0.88 mm appeared to be more sensitive to these chemicals. Moreover, our results showed that BPA and DES did not inhibit GVBD.     

Characterization of cholinesterases in marbled sole, Limanda yokohamae, and their inhibition in vitro by the fungicide iprobenfos

Cholinesterases (ChEs) have been characterized in marbled sole (Limanda yokohamae) for use as a possible biomarker of pollution exposure. In brain, ChEs existed almost exclusively (>95%) as acetylcholinesterase (AChE) whereas in muscle, about 20-30% of ChE activity was in the form of butyrylcholinesterase (BChE; pseudocholinesterase). Acetylthiocholine and butyrylthiocholine (identified in mammalian studies as diagnostic substrates for AChE and BChE respectively) were hydrolyzed mainly, but not exclusively, by these enzymes. The inhibitors BW284C51 and iso-OMPA (identified in mammalian studies as diagnostic inhibitors of AChE and BChE respectively) were not specific for these enzymes in marbled sole. Brain AChE and muscle AChE and BChE were characterized in terms of their kinetic properties (KM etc.) and optimal conditions (substrate concentration, protein concentration, pH etc.) were established to allow routine assays of ChE activity to proceed under pseudo-first order conditions. The sensitivity of ChEs to a locally significant pesticide, iprobenfos (IBP; kitazin) was established in terms of IC50 concentrations. Brain AChE was relatively insensitive to IBP, but muscle AChE and BChE were sensitive to IBP concentrations in the high nM range. However, ambient IBP concentrations in Korean coastal waters are usually not high enough to cause detectable ChE inhibition in this species.     

Soil moisture monitoring on a steep hillside

In this study, a soil monitoring system for a hillslope with steep relief and shallow soil depth was designed and installed to represent efficiently the spatial and temporal features of soil moisture. The study was conducted on a mountainous hillslope of the Sulmachun catchment (northeastern South Korea). The positions of soil moisture sensors were determined through a sequential procedure including intensive geomorphologic surveying of the study area, surface and subsurface terrain analysis, and inverse surveying. Using 26 sensors, soil moisture data from 11 locations were measured and recorded at hourly intervals over 380 h from 6 to 22 November 2003. Soil moisture response patterns were captured for a few consecutive rainfall events. The monitoring results are discussed in the context of soil moisture variations with terrain attributes. The immediate recharge and fast recession after a peak are the primary features of soil moisture in the upper zone. Stability and significant storage increase are distinct characteristics of soil moisture in the buffer zone and the flow path zone respectively. Spatial distribution of temporal soil moisture variations can be characterized in terms of recession, stability and recharge depending upon the topographic classification of a hillslope for this approach. Copyright © 2007 John Wiley & Sons, Ltd.     

Expansion of the planar-fit method to estimate flux over complex terrain

An expanded planar-fit (PF) method over complex terrain is presented and applied to coordinate rotation of the eddy-covariance (EC) flux and vertical velocity estimation. Theoretical analysis indicates that PF coefficients depend on wind direction, and an expression of vertical velocity is deduced. We applied the theory using 1?year of observations from the KoFlux site in the Gwangneung Forest in Korea and investigated the influence of wind direction on the PF method. Then, we performed an expansion of the PF method to consider dependence of PF coefficients on wind direction and applied the PF method to every sector. The results show that the PF coefficients and tilt angles over complex terrain vary with wind direction. Two hundred 30-min data sets are sufficient to derive stable PF coefficients over hilly terrain for each sector. The relative difference in eddy-covariance flux between the general planar fit (GPF) and sector planar fit (SPF) is less than 10% for the scalar flux and about 18% for friction velocity. Vertical velocity and vertical advection (VA) terms were also calculated and compared using SPF and GPF methods, and a normal distribution and diurnal trend of real vertical velocity on clear days are presented.     

Temporal and geographical trends in the genotoxic effects of marine sediments after accidental oil spill on the blood cells of striped beakperch (Oplegnathus fasciatus)

To determine the impact of genetic toxicity caused by the Hebei Spirit oil spill on December 7, 2007, we measured DNA damage in the blood cells of striped beakperch in vitro after exposure to extracts from sediments in the Taean area. The objective of this study was to investigate temporal changes of toxic effects caused by residual PAHs in the sediments up to 18 months after an oil spill. In conclusion, DNA damage had reduced over this 18-month period; that is, the sediments recovered quickly from the oil pollution. In addition, statistically significant correlations between PAHs and DNA damage were observed. Because the comet assay is sensitive to DNA damage induced by genotoxic substances from the polluted sediments, the comet assay can be considered a useful tool as a biomarker in investigating genetic toxicity in environmental monitoring and elucidating the recovery of oil pollution after oil spill as well.     

Forest fire risk mapping of Kolli Hills, India, considering subjectivity and inconsistency issues

Forest fires have adverse ecological, economic, and social impacts. In this light, the present research aimed, first, to construct a fire risk model using a GIS-based multi-criteria analysis and second, to derive a forest fire risk modeling strategy that alleviates the problem of inconsistency in the assigning of scores and weights to forest fire categories and layers. Third, the local-orientation effects and causes, which are relevant to the subjectivity problem, were investigated by comparing the risk scoring and weighting outcomes from Indian and Korean expert groups (IEG and KEG). Fourth, forest fire factors that can be considered regional and global also were investigated. Kolli Hills, India, was selected as the study area in this research. In the interests of alleviating the inconsistency problem, a weighting and scoring scheme based on the analytic hierarchy process was applied. The experiences from the existence of prevailing westerly winds, the most common forest types (i.e., in Korea: pine trees), and the different anthropogenic pressures between Korea and India resulted in the different scoring and weighting decisions of the two expert groups. Among the five fire risk factors, slope, road, and settlement can be considered to be global factors. On the other hand, forest cover and aspect are regional factors that can be more influenced by local environmental conditions. When considering the producer’s accuracy, the approach of the IEG together with the natural breaks thresholding method provided the best fire risk mapping result. On the other hand, the model from the IEG with equal interval provided the best result from the viewpoint of user’s accuracy and overall accuracy. Overall, this paper proposes a forest fire risk mapping procedure as basis for developing a global forest fire risk modeling in the future, where a series of standardized modeling steps and variables should be defined.     

A study on measurement and analysis of radon-222 (uranium series) emitted to the atmosphere from construction materials (cement block, kaolin brick, and gypsum board) in living environment

The purpose of this study was to measure, compare, and analyze the air concentration of radon that was emitted to the atmosphere from construction materials such as cement brick, tile, red clay tile, and gypsum tile. The study method was to use continuous radon monitoring equipment (RTM 1688-2) to measure concentrations of radon and thoron contained in brick, tile, red clay tile, and gypsum tile. According to the measurement results, the cement brick among the four samples showed the highest measurement value for radon, while the red clay tile showed the highest measurement value for thoron. When the radon emission concentration was estimated based on materials required for construction per unit area (3.3 m²) in an actual construction, the cement brick had the highest measurement values for radon and thoron. This study confirmed the degree of radon emission from construction materials. The purpose of this study was also to suggest a method to examine the effects of radon and reduce the dose of personal radiation exposure. It is believed that the government should be active in publicizing and managing use of construction materials that have lower levels of radon emission.     

Integrative assessment of sediment quality in terms of chemical contamination in Jinhae Bay,South Korea

The assessment of sediment quality by considering chemical contaminants is required for the effective management of coastal environments. In this study, complex data sets of heavy metals and organic pollutants were integrated to evaluate sediment quality. Thirty-two target pollutants were quantitatively determined in surface sediments from 80 stations in Jinhae Bay, South Korea. A sediment quality index (SQI) was derived by combining the functions of “scope” (the number of variables that do not meet guideline objectives) and “amplitude” (the magnitude by which these variables exceed the guideline objective). The SQI reflects the spatial gradient and differences in the contamination status with regard to heavy metals and organic pollutants in Jinhae Bay. Fifty-nine out of eighty stations surveyed (74%) were classified as being in “excellent” or “good” condition according to the SQI, and no stations were in a “poor” condition. The mean sediment quality guideline quotient (mSGQq) ranged from 0.06 to 0.31 (from nontoxic to marginally toxic). Acute sediment toxicity leading to amphipod mortality was recorded at 17 stations (21%) of the 80 surveyed, where the mortality rate was slightly over 20%. No significant relationship was observed between sediment toxicity and the concentration of each toxicant or mSQGq.     

Biochemical responses of juvenile rockfish (Sebastes schlegeli) to low levels of dissolved oxygen in Gamak Bay

Gamak Bay is one of the largest aquaculture areas in the South Sea of Korea and exhibits hypoxia conditions during the summer. The harmful effects of hypoxia on aquaculture fish stock have not been elucidated. This study describes the biochemical effects of low levels of dissolved oxygen (DO) on cultivated juvenile Sebastes schlegeli in Gamak Bay. The hypoxia-inducible factor 1α (HIF1α) gene was induced significantly in S. schlegeli collected from low oxygen level areas, which suggests that fluctuations in the DO induces the expression of HIF1α. The level of antioxidant enzyme exhibited significantly higher activities in fish obtained from station F2 in which low levels of DO were shown in 2010 and 2011. The results of this study demonstrate that cultivated S. schlegeli are affected by the low levels of DO in Gamak Bay and superoxide dismutase enzymes operate dependently with HIF1α. The plasma glucose level did not exhibit significant difference in the fish among the sampling stations. We noted that HIF1α and the superoxide dismutase enzymes are useful biomarkers that might enable the detection of otherwise unnoticed hypoxic stress.