• Korean Journal of Environmental Biology
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• v.38 no.2
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• pp.231-247
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• 2020

The seasonal variation in the zooplankton community and hydrographic conditions were examined in three regions (inner, central, and outer regions) of Gamak Bay, Korea. Zooplankton samples were collected over a period of 12 months from January to December 2006. The hydrographical parameters of temperature, salinity, chlorophyll-a concentrations, dissolved oxygen, and chemical oxygen demand were measured. The total zooplankton density varied from 411 to 58,485 ind. m^-3, with peaks in early summer. A total of 65 taxa accounted for approximately 86.9% of the annual mean zooplankton density: Noctiluca scintillans (30.9%) Paracalanus parvus s. l.(24.3%), Acartia omorii(11.9 %), Eurytemora pacifica (5.7%), cladocerans (4.1%), cirriped larvae (3.8%), Oithona similis (3.7%), and Pseudevedne tergestina(2.5%). Copepods dominated numerically throughout the year and comprised 54.3% of the total zooplankton. Most of the dominant copepods showed a well-defined seasonal pattern. The density and diversity of zooplankton in Gamak Bay were influenced by the hydrographic environment that was subject to significant spatial and temporal variations. Multivariate statistics showed that seasonal temperature was the most significant predictor of zooplankton taxa, density, and diversity, as well as the density of dominant taxa. Our results suggest that fluctuations in the zooplankton populations, particularly copepods, followed progressive increments in the temperature and COD concentrations.

• ALGAE
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• v.26 no.4
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• pp.333-342
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• 2011

Macroalgae are important primary producers in marine ecosystem. They don't only play an important role as bioindicators but also provide economic resources for humans. Seasonal and vertical variations in seaweed species composition and biomass were examined to determine the ecological status of seaweed beds around Udo, near Jeju Island. We obtained samples at two sites in the high-intertidal to subtidal zones using the quadrat method between June 2010 and May 2011. A total of 262 species were collected, including 31 green, 61 brown, and 170 red algae. The composition of algal species revealed a decrease in species growing in cold water in comparison with the list 20 years ago. The macroalgal mean biomass (g wet wt $m^{-2}$) was 3,476 g and 2,393 g from the two sites, respectively. Ecklonia cava had the greatest biomass at both sites. The seasonal dominant species by biomass at site 1 from the low-intertidal to 1-3 m depth of the subtidal zone was mostly comprised of thick-leathery form, such as Sargassum hemiphyllum, S. coreanum, and Ecklonia cava, whereas site 2 was comprised of the turf form, such as Chondrophycus intermedius, Chondracanthus intermedius, Dictyopteris prolifera, and Gelidium elegans. The current ecological status of the seaweed community in Udo is stable based on diversity and dominance indices.

• Ocean and Polar Research
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• v.24 no.2
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• pp.123-134
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• 2002

Seasonal variations of settling particles and metal fluxes were monitored at a nearshore site of Marian Cove, King Geroge Island, Antarctica from 28th February 1998 to 22nd January 2000. Near-bottom sediment traps were deployed at 30m water depth of the cove, and sampling bottles were recovered every month by SCUBA divers. Total particulate flux and metal concentrations were determined from the samples. Total particulate flux showed a distinct seasonality, high in austral summer and low in austral winter: the highest flux $(21.97g\;m^{-2}d^{-1})$ was found in February of 1999, and the lowest $(2.47g\;m^{-2}d^{-1})$ in September of 1998, when sea surface was frozen completely. Lithogenic particle flux accounted for 90% of the total flux, and showed a significantly negative correlation with the thickness of snow accumulation around the study site. It was suggested that the most of the lithogenic particles trapped in the bottles was transported by melt water stream from the surrounding land. Fluxes of Al, Fe, Ti, Mn, Zn, Cii, Co, Ni, Cr, Cd, and Pb showed similar seasonal variations with the total flux, and their averaged fluxes were 34000, 9000,960, 180, 13.8, 17.6, 3.0,2.1, 5.4, 0.02, and $1.5nmol\;m^{-2}d^{-1}$ respectively. Among the metals, Cu and Cd showed the most noticeable seasonal patterns. The Cd flux correlated positively with the fluxes of biogenic components while the Cu flux correlated with both the lithogenic and biogenic particle fluxes. The Cu flux peak in the late summer is likely related to a substantial amount of inflow of ice melt water laden with Cu-enriched lithogenic particles. On the other hands, the Cd flux peak in the early spring may be associated with the unusually early occurred phytoplankton bloom.

• Journal of Environmental Science International
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• v.21 no.10
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• pp.1275-1286
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• 2012

Coastal marine ecosystem plays important role of spawning and nursery grounds for fisheries resources. Yongil Bay is one of major coastal marine ecosystems, which is located in the southwestern East Sea of Korea. Species composition and abundance of marine organism in the Yongil Bay were investigated by season from March to November 2009. Gill net and pot fisheries were used for survey of pelagic and demersal species composition, and collected 106 species, 67 families, and 7 taxa of fisheries resources from the coastal ecosystem. Species were included 2 species in Ascidiacea, 2 species in Bivalvia, 6 in Cephalopoda, 22 in Crustacea, 5 in Echinodermata, 12 in Gastropoda, and 57 in Pisces. Diversity indices (Shannon index, H') showed seasonal variation with low value of 2.11 in winter, and high value of 2.63 in autumn. Main dominant species were Asterias amurensis, Pleuronectes yokohamae, Siphonalia spadicea fuscolineata, Trachurus japonicas, Sillago japonica, Conger myriaster, Volutharpa ampullaceal, Engraulis japonicus, Asterina pectinifera, and Portunus (Portunus) sanguinolentus that were occupied over 71.5% of total individuals, and 52.9% of wet weight. Seasonal variations of fisheries resources composition were discussed on correlationships with those of environmental factors in the coastal ecosystem of the Yongil Bay in Korea. Those results from this study will provide scientific data and information to develop the ecosystem-based coastal fisheries assessment and management system in Korea.

• Asian Journal of Atmospheric Environment
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• v.10 no.1
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• pp.22-31
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• 2016

Active fire products from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite observation during the 16 years from 2000-2015 were analyzed to estimate spatial and temporal variations of wildland fires over East Asia (region of interest: $20^{\circ}N-55^{\circ}N$, $100^{\circ}E-150^{\circ}E$). GLOBCOVER 2009 land cover data were also used to investigate the trend in wildfire occurrence with respect to each land cover type. Statistical analysis showed that the highest number of wildland fires occurred in the evergreen and vegetation covered areas, and strong seasonal variations were found in these areas. Total numbers of fires were 283,683 and 202,543, respectively. In particular, the wildland fires in croplands occurred mainly during summer season and distinguishable increasing trends were found. The correlations between number of wildland fires and air pollutants, such as black carbon, organic matter, and carbon monoxide, were also calculated in order to investigate the intensity of the air pollution caused by the wildland fires. Positive correlation between total column carbon monoxide contents and the occurrence of wildland fire was found. In addition, this correlation was higher than the correlation between fire occurrence and black carbon or organic matter. These results indicate that a significant amount of carbon monoxide originated from the wildland fires and influenced the regional atmospheric environment in East Asia.

• Asian Journal of Atmospheric Environment
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• v.12 no.3
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• pp.244-254
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• 2018

Ulaanbaatar, the capital of Mongolia, is subject to high levels of atmospheric pollution during winter, which severely threatens the health of the population. By analyzing surface meteorological data, ground-based LIDAR data, and radiosonde data collected from 2008 to 2016, we studied seasonal variations in particulate matter (PM) concentration, visibility, relative humidity, temperature inversion layer thickness, and temperature inversion intensity. PM concentrations started to exceed the 24-h average standard ($50{\mu}g/m^3$) in mid-October and peaked from December to January. Visibility showed a significant negative correlation with PM concentration. Relative humidity was within the range of 60-80% when there were high PM concentrations. Both temperature inversion layer thickness and intensity reached maxima in January and showed similar seasonal variations with respect to PM concentration. The monthly average temperature inversion intensity showed a strong positive correlation with the monthly average $PM_{2.5}$ concentration. Furthermore, the temperature inversion layer thickness exceeded 500 m in midwinter and overlaid the weak mixed layer during daytime. Radiative cooling enhanced by the basin-like terrain led to a stable urban atmosphere, which strengthened particulate air pollution.

• Fisheries and Aquatic Sciences
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• v.1 no.1
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• pp.113-121
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• 1998

A relationship between sea level variations in the Korea Strait (the western and the eastern channels) and the Tokara Strait in the Kuroshio region is examined using daily-mean sea level data from 1966 to 1986. The seasonal variation of the sea level difference (SLD) between Izuhara and Pusan (the western channel) is most periodic: the positive anomalies appear from summer to autumn, and the negative anomalies from winter to spring year to year, whereas SLDs neither between Hakata and Izuhara (the eastern channel) nor between Naze and Nishinoomote (the Tokara Strait) show such a periodic variation. Much similarity has been found between SLDs in the eastern channel and the Tokara Strait, and in particular they were closely correlated in a special event of the Kuroshio region, such as a large meander of the Kuroshio. This paper shows that the periodic seasonal variation of the SLDs in the western channel should be less related to the Kuroshio region. This result also implies that the variation of SLD in the western channel is largely influenced by local factors, such as the bottom cold water in the western channel in summer, rather than from the Kuroshio region.

• Korean Journal of Ichthyology
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• v.10 no.2
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• pp.155-163
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• 1998

To determine diel and seasonal variations in abundance and species composition of fishery resources, day and night samples were collected by a bag net from April through November 1997 off Kogunsan-gundo. A total of 75 species was collected. The total catch was consisted of 71% fish, 18% shrimps, 7% cephalopods and 4% crabs. Pholis fangi and Engraulis japonicus predominated, and accounted for 87% of the total number of fish collected. Most of them were larvae and juvniles. P. fangi and Ammodyres personatus occurred from April to June, and E. japonicus occurred from July to November, suggesting that they used the coastal areas as nursery ground at the different season to avoid competition. Dominant fish larvae and juveniles showed the significant diel difference in catch.

• Journal of Korean Society for Atmospheric Environment
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• v.7 no.1
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• pp.17-22
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• 1991

Total suspended particulates (TSP) in the atmosphere was collected and size-fractionated by Andersen high volume air sampler for one year (Mar. 1987 $\sim$ Feb. 1988) in Seoul. The concentrations of several polycyclic aromatic hydrocarbons and heavy metals were determined to investigate the atmospheric concentrations, seasonal variations and its relationship with the size distribution of suspended particulate matter. The arithmetic mean concentration of total suspended particulates was 200.44 $\mug/m^3$. The concentrations of heavy metals were 2433.80 for Fe, 629.49 for Zn, 600.71 for Pb, 143.87 for Cu, and 107.21 $ng/m^3$ for Mn, respectively. The concentrations of PAHs were 3.83 for benzo(a) pyrene, 2.95 for benzo(k)fluoranthene, and 4.42 $ng/m^3$ for benzo(ghi)perylene, respectively. PAHs, Pb and Zn abounded in particles below 2.0 $\mu$m, while Fe and Mn aboounded in particles above 2.0 $\mu$m. TSP and its chemical compositions showed the seasonal variations. The concentrations of anthrophogenic pollutants like TSP, PAHs and heavy metals in the fine particles were highest in winter and lowest in summer. PAHs and Pb analyzed showed significant correlations between each other and between TSP concentration in fine particles, indicating that the particles in which they are contained have a similar behavior in the atmosphere.

• Journal of Korean Society for Atmospheric Environment
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• v.10 no.4
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• pp.252-259
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• 1994

A ground station has been established at Kosan, Cheju Island, since January of 1992 for the monitoring of background air Pollutant levels in Korea. Anthropogenic pollutant sources and meteorological conditions of Kosan were surveyed. Concentrations of SO$_2$, NO, NO$_{y}$ and $O_3$, were measured and analyzed for the period of February through December, 1992. The annual means of NO and SO$_2$, levels were very low in comparison to other urban's levels and similiar to other country's background levels. The annual mean of $O_3$, level was higher than urban's but comparable to other coastal region's. The NO concentration showed a distinct seasonal and diurnal variations. Summer peak was detected in the monthly means of NO and smooth peak around noon was found in the annual means of hourly data. Diurnal variation of the SO$_2$ concentration was barely detected but a slice increase in winter was detected. The $O_3$, concentration data, however, showed seasonal and diurnal variations similar to the urban's.an's.