• Korean Journal of Environmental Biology
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• v.24 no.3
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• pp.230-239
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• 2006

Nutrient over-enrichment as a consequence of anthropogenic loading leads to eutrophication, which has the detrimental effects on river and stream ecosystems. To examine dynamics of factors causing cultural eutrophication in a over-licked mountain stream due to anthropogenic loading, physicochemical parameters were measured from 5 stations in the upper Daecheon stream, Busan, from January 2002 to May 2003. The five study sites were located along the stream gradient. DC1 is upper most clean site, and DC5 is located at the lowest area. Wastewater was released into the stream from just upstream of DC2 site. Water column ammonium and phosphate concentrations were higher during winter than other seasons, while water column nitrate +nitrite concentration did not show clear seasonal variation. Water column ammonium, nitrate+nitrite and phosphate concentrations were lowest at DC1 and highest at DC2 in which waste water loading occurred. TOC and DOC, conductivity, turbidity, and BOD in the water column were also increased drastically at DC2, and then decreased at DC5. Sediment pore water phosphate concentrations during winter and spring were higher than those in summer and fall, while sediment pore water ammonium and nitrate +nitrite concentrations showed no seasonal trend. Sediment pore water ammonium and phosphate concentration were also increased at DC2 and slightly decreased at DC5, while sediment pore water nitrate+nitrite concentration was highest at DC5. Organic matter and inorganic nutrients at up-stream of Daechon stream significantly increased as a result of wastewater discharge, and the nutrient concentrations decreased at low-stream suggesting self-purification ability of the stream.

• Horticultural Science & Technology
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• v.31 no.3
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• pp.282-288
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• 2013

This study was conducted to investigate the quality characteristics of eight everbearing strawberry cultivars and the effect of precooling treatment to maintain the quality during storage and shelf life of 'Charlotte'. Several quality parameters including firmness, soluble solids content (SSC), color, soluble sugars, and organic acids were evaluated. For Successful marketing everbearing strawberries required more than 1 N of firmness and $6^{\circ}Brix$ of SSC, respectively. 'Albion', 'Charlotte', and 'Goha' cultivars were higher in fruit SSC and 'Charlotte' cultivar was higher in fruit firmness among eight cultivars examined in this study. Fruit had more bright red color in 'Charlotte', 'Flamingo', 'GW-4', and 'San Andreas', which may reflect the consumer acceptance. Physicochemical characteristics of 'Charlotte' strawberry after with/without room precooling treatment were evaluated during storage at $4^{\circ}C$, $10^{\circ}C$, and $25^{\circ}C$ and additional 3 days at $25^{\circ}C$ for shelf-life. Weight loss increased about 8% in the fruits stored at $25^{\circ}C$ for 3 days, while in low temperature storage was about 2% for 7 days showing precooling was more effect on during shelf life periods rather than storage periods. Decay was not found during storage at $4^{\circ}C$ regardless of precooling treatment, but fungal growth was found in all the treatments after transferred to room temperature. Precooling treatment did not affect fruit color in shelf life period. For advanced marketing, everbearing strawberry should maintain in low temperature less than $4^{\circ}C$ to sustain quality, but the room precooling showed less significant effect to maintain quality on 'Charlotte' cultivar.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.4
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• pp.321-337
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• 2010

Long-term trends and distribution patterns of water quality were investigated in the Mokpo coastal areas of the Yellow Sea, Korea from 1979 to 2009. Water samples were collected at 5 stations and physicochemical parameters were analyzed including water temperature, salinity, suspended solids (SS), chemical oxygen demand (COD), dissolved oxygen (DO) and nutrients. Spatial distribution patterns of temperature, pH and DO were not clear among stations but the seasonal variations were distinct except ammonium. The trend analysis by principal component analysis (PCA) during 30 years revealed the significant variations in water quality in the study area. Spatial water qualities were discriminated into 3 clusters by PCA; station cluster 1, 2~4, and 5. Annual water qualities were clearly discriminated into 4 surface water clusters and 2 bottom water clusters by PCA. By this multi-variate analysis, the annual trends were summarized as the followings; water temperature, pH and COD tended to increase from late 1980's, salinity to decrease, phosphate to increase from 1994 and dissolved inorganic nitrogen to increase, due to the input of fresh water same as shown in Kyoungin coastal area, Asan coastal area, Choensoo bay and Gunsan coastal area.

• Korean Journal of Environmental Biology
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• v.37 no.3
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• pp.433-445
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• 2019

This study was designed to develop simple tools to easily and efficiently predict the occurrence of algal bloom in agricultural lakes. Physicochemical water quality parameters were examined to reflect the phytoplankton productivity in 182 samples collected from 15 agricultural lakes from April to October 2018. Total phytoplankton abundance was significantly correlated with chlorophyll-a (Chl-a) (r=0.666) and Secchi depth (SD) (r= -0.351). The abundances of cyanobacteria and harmful cyanobacteria were also correlated with Chl-a (r=0.664, r=0.353) and SD (r= -0.340, r= -0.338), respectively, but not with total nitrogen (TN) and total phosphorus (TP). The Chl-a concentration was correlated with SD (r= -0.434), showing a higher similarity than phytoplankton abundance. Therefore, Chl-a and SD were selected as diagnostic factors for algal bloom prediction, instead of analyzing the standing crop of harmful cyanobacteria used in algae alarm systems. Specifically, accurate diagnoses were made using realtime SD measurements. The algal bloom diagnostic tool is an inverse cone-shaped container with an algal bloom diagnosis chart that modified SD and turbidity measurement methods. Lake water was collected to observe the number of rings visible in the container or the number indicated in each ring, depending on the degree of algal bloom,and to determine the final stage of algal blooming by comparison to the colorimetric level on the diagnosis chart. For an accurate diagnosis, we presented 4-step diagnostic criteria based on the concentration of Chl-a and the number of rings and a fan-shaped algal bloom diagnosis chart with Hexa code names. This tool eliminated the variables and errors of previous methods and the results were easily interpreted. This study is expected to facilitate the diagnosis of algal bloom in agricultural lakes and the establishment of an efficient algal bloom management plan.

• The Korean Journal of Pesticide Science
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• v.4 no.2
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• pp.21-28
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• 2000

A new fourty six 2-(4-(6-chloro-2-benzoxazolyloxy)phenoxy)-N-phenylpro- pionamide derivatives were synthesized and the herbicidal activities against rice plant and barnyard grass with pre-emergence in down land were measured. The structure activity relationships (SAR) between the activities and physicochemical parameters of the substituted(X) N-phenyl group in substrates were analyzed and discussed by Free- Wilson and Hansch method from the basis on the former study (Sung. et. al., 1999). The conditions of selective herbicide activity both the barnyard grass and rice plant are shown that the optimal hydrophobicity, $({\pi})_{opt.}=1.34$ and electron donating with field effect (F<0) of meta and ortho, para-substituted mono or disubstituent on the N-phenyl ring were found to contribute significantly. The herbicidal activities against barnyard grass are roughly the same as the results in up land whereas damage to rice plant in down land more increase than that of up land. Degradation products in water are 2-(4-(6-chloro-2-benzoxazolyloxy)phenoxy)propionic acid ((A)) (obs. pKa=4.35 & obs. logP=4.77) and 6-chloro-2-benzoxazolone (B) (obs. pKa=8.40 & obs. logP=2.90). These results were supposing that the hydrolysis product of substrates, (A) is comparatively absorbed in rice plant but not in barnyard grass. And it is assumed from the SAR equations that the 2,6-dimethyl-4-methoxymethyl group substituent ($pI_{50}=5.41$, 3g/ha) is selected as the most highest herbicidal activity against barnyard grass in green house.

• Korean Journal of Ecology and Environment
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• v.38 no.4 s.114
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• pp.461-474
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• 2005

Physicochemical parameters, plankton community structure, and sediment were surveyed from 1988 to 2002, at two months interval, in a eutrophic coastal lagoon (Lake Songji, Korea). The lake basin is separated from the sea by a narrow sand dune, and a shallow sill divides the lake basin into two sub-basins. The stable stratifications and chemoclines are maintained all through the year at 1-2 m depth. DO was often very low (<1 $mgO_2\;{\cdot}\;L^{-1}$) in the monimolimnion. Secchi disc transparency was in the range of 0.5-2.7 m. TP, TN, and Chl. a concentration in the mixolimnion were 0.015-0.396 $mgP\;{\cdot}\;L^{-1}$), 0.223-3.521 $mgN\;{\cdot}\;L^{-1}$, and 0.5-129.8 mg ${\cdot}\;m^{-3}$, respectively. TSI was in the eutrophic range of 54 to 62. Sediment was composed of silt and coarse silt. COD, TP, and TN content of the sediment were 51.4-116.9 $mgO_2\;{\cdot}\;gdw^{-1}$, 0.04-1.46 $mgP\;{\cdot}\;gdw^{-1}$ and, 0.12-1.03 $mgN\;{\cdot}\;gdw^{-1}$, respectively. The 49 phytoplankton species were identified. The maximum phytoplankton abundance obscured the lake in September 2001 (max. density: 23,350 cells ${\cdot}\;mL^{-1}$. The Chlorophyte Schroederia judayi was dominant species in summer (max. density: 20,417 cells ${\cdot}\;mL^{-1}$). The lake showed unique limnological features of a brackish lagoon in respect to biological community, chemical characteristics, and physical phenomena.

• Food Science of Animal Resources
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• v.31 no.6
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• pp.921-927
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• 2011

To compare pork quality from different pig species domesticated for Korean consumers, the meat quality characteristics of 5 different pure breeds of Landrace (L), Yorkshire (Y), Duroc (D), Berkshire (B), and Chester White (C) were determined from the 3 parts of loins, butts, and bellies. The fat content of loins was higher in breed D than in the other breeds, while that of butts and bellies was higher in breed B. The CIE color $a^*$ and $b^*$ values of the loins and butts from breed C were lower than those of the other breeds, but the color values of the belly part did not significantly differ by breed due to the high fat accumulation. The drip loss and cooking loss significantly differed depending on meat parts: breeds D and B were inferior in loins and butts but superior in bellies. The lipid oxidation of raw meat did not increase during the 7 d storage. The cooked butts of breed C had less thiobarbituric acid-reactive substances values than those of the other breeds at 7 d, and the cooked bellies of breeds D and B had less. Moreover, there were only minimal differences in fatty acid compositions by pork breed and part. From the view points of the physicochemical and organoleptic analysis of pork from different pig species, it is estimated that breed D had better meat quality in the loin part and breed B had better meat quality in the butt. The belly meat quality of breed C showed the least value. Although the meat quality of pig species differed depending on the parts and it was difficult to compare the meat quality of a part using the meat quality parameters of another part, the result of this study could provide basic information that can be used to improve the meat quality of different parts of pig species.

• Economic and Environmental Geology
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• v.49 no.5
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• pp.371-380
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• 2016

This study aims to identify the mineraloical and petrographical characteristics of caprock from drilling cores of Pohang basin as a potential $CO_2$ storage site. Experiments and modeling were conducted in order to investigate the geochemical and mineralogical caprock effects of carbon dioxide. A series of autoclave experiments were conducted to simulate the interaction in the $scCO_2$-caprock-brine using a high pressure and temperature cell at $50^{\circ}C$ and 100 bar. Geochemical and mineralogical alterations after 15 days of $scCO_2$-caprock-brine sample reactions were quantitatively examined by XRD, XRF, ICP-OES investigation. Results of mineralogical studies, together with petrographic data of caprock and data on the physicochemical parameters of brine were used for geochemical modeling. Modelling was carried out using the The Geochemist's Workbench 11.0.4 geochemical simulator. Results from XRD analysis for caprock sample showed that major compositional minerals are quartz, plagioclase, and K-feldspar, and muscovite, pyrite, siderite, calcite, kaolinite and montnorillonite were included on a small scale. Results from ICP-OES analysis for brine showed that concentration of $Ca^{2+}$, $Na^+$, $K^+$ and $Mg^{2+}$ increased due to dissolution of plagioclase, K-feldspar and muscovite. Results of modeling for the period of 100 years showed that the recrystallization of kaolinite, dawsonite and beidellite, at the expense of plagioclase and K-feldspar is characteristic. Volumes of newly precipitation minerals and minerals passing into brine were balanced, so the porosity remained nearly unchanged. Experimental and modeling results indicate the interaction between caprock and $scCO_2$ during geologic carbon sequestration can exert significant impacts in brine pH and solubility/stability of minerals.

• Korean Journal of Ecology and Environment
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• v.39 no.2 s.116
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• pp.145-156
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• 2006

The objective of this study was to evaluate biological health conditions and physicochemical status using multi-metric models at five sites of the Keum-Ho River during August 2004 and June 2005. The research approach was based on a qualitative habitat evaluation index (QHEI), index of biological integrity (IBI) using fish assemblage, and long-term chemical data (1995 ${\sim}$ 2004), which was obtained from the Ministry of Environment, Korea. For the biological health assessments, regional model of the IBI in Korea (An,2003), was applied for this study. Mean IBI in the river was 30 and varied from 23 to 48 depending on the sampling sites. The river health was judged to be "fair condition", according to the stream health criteria of US EPA (1993) and Barbour et al. (1999). According to the analysis of the chemical water quality data of the river, BOD, COD, conductivity, TP, TN, and TSS largely varied epending on the sampling sites, seasons and years. Variabilities of some parameters including BOD, COD, TP, TN, and conductivity were greater in the downstream than in the upstream reach. This phenomenon was evident in the dilution by the rain during the monsoon. This indicates that precipitation is a very important factor of the chemical variations of water quality. Community analyses showed that species diversity index was highest (H=0.78) in the site 1, while community dominance index was highest in the site 3, where Opsariichthys uncirostris largely dominated. In contrast, the proportions of omnivore and tolerant species were greater in the downstream reach, than in the upstream reach. Overall, this study suggests that some sites in the downstream reach may need to restore the aquatic ecosystem for better biological health.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.3
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• pp.203-218
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• 2011

Long-term trends and distribution patterns of water quality were investigated in the Yeoja Bay of South Sea, Korea from 1976 to 2010. Water samples were collected at 3 stations and physicochemical parameters were analyzed including water temperature, salinity, hydrogen ion concentration (pH), dissolved oxygen (DO), chemical oxygen demand (COD), suspended solids (SS) and nutrients. Spatial distribution patterns of temperature, pH and DO were not clear among stations but the seasonal variations were distinct except ammonium. The trend analysis by principal component analysis (PCA) during 31 years revealed the significant variations in water quality in the study area. Spatial water qualities were discriminated into 2 clusters by PCA; station cluster 1 and 2~3. Annual water qualities were clearly discriminated into 4 clusters by PCA. By this multi-variate analysis, the annual trends were summarized as the followings; water temperature, COD and SS tended to increase from late 1970's, decreased salinity, and increased phosphate from 1991 to 2001 and increased dissolved inorganic nitrogen. Water quality was showed by the input of fresh water same as those of Kyoungin coastal area, Asan coastal area, Choensoo bay, Gunsan coastal and Mokpo coastal area in the Yeoja Bay.