• Korean Journal of Environmental Biology
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• v.40 no.4
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• pp.464-476
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• 2022

In recent years, macroalgal bloom occurs frequently in coastal oceans worldwide. It might be attributed to accelerating climate change. "Green tide" events caused by proliferation of green macroalgae (Ulva spp.) not only damage the local economy, but also harm coastal environments. These nuisance events have become common across several coastal regions of continents. In Korea, green tide incidences are readily seen throughout the year along the coastlines of Jeju Island, particularly the northeastern coast, since the 2000s. Ulva species are notorious to be difficult for morphology-based species identification due to their high degrees of phenotypic plasticity. In this study, to investigate temporal variation in Ulva community structure on Jeju Island between 2015 and 2020, chloroplast barcode tufA gene was sequenced and phylogenetically analyzed for 152 specimens from 24 sites. We found that Ulva ohnoi and Ulva pertusa known to be originated from subtropical regions were the most predominant all year round, suggesting that these two species contributed the most to local green tides in this region. While U. pertusa was relatively stable in frequency during 2015 to 2020, U. ohnoi increased 16% in frequency in 2020 (36.84%), which might be associated with rising sea surface temperature from which U. ohnoi could benefit. Two species (Ulva flexuosa, Ulva procera) of origins of Europe should be continuously monitored. The findings of this study provide valuable information and molecular genetic data of genus Ulva occurring in southern coasts of Korea, which will help mitigate negative influences of green tide events on Korea coast.

• Analytical Science and Technology
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• v.20 no.5
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• pp.383-392
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• 2007

The water soluble components were analyzed in the $PM_{2.5}$ fine particles collected at the 1100 site of Mt. Halla for the spring seasons between 1998 and 2004. The $PM_{2.5}$ mass concentrations were within $13.4{\pm}9.6{\sim}21.7{\pm}20.0{\mu}g/m^3$, and the concentrations of ionic components were in the order of nss-$SO{_4}^{2-}$ > $NH{_4}{^+}$ > $NO{_3}{^-}$ > $Ca^{2+}$ > $K^+$ > $Na^+$ > $Cl^-$ > $Mg^{2+}$, in which the concentration of nss-$SO{_4}^{2-}$($3.41{\pm}2.42{\mu}g/m^3$) was the highest. The concentrations of $NH{_4}{^+}$, $SO{_4}^{2-}$, and $NO{_3}{^-}$, the secondary pollutants, were respectively 0.60~1.50, 2.86~4.42, and $0.24{\sim}1.57{\mu}g/m^3$, which had occupied 88 % of the total ionic components, on the other hand, the concentrations of marine species were less than 5 %. The nss-$SO{_4}^{2-}$ showed the high correlation with $NH{_4}{^+}$, $K^+$, so that $NH{_4}{^+}$ and nss-$SO{_4}^{2-}$ might exist in the form of $(NH_4)_3H(SO_4)_2$ and $(NH_4)_2SO_4$ in fine particles. From the backward trajectory analysis, in case of high concentrations of $NH{_4}{^+}$ and nss-$SO{_4}^{2-}$ simultaneously, the air masses were originated and stagnated at the east region of China for a while, then moved into the atmosphere of Jeju. However, in case of $NO{_3}{^-}$ and nss-$Ca^{2+}$, the air masses originated at China and Siberia were moved into Jeju via the eastern China.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.3
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• pp.195-207
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• 2000

Organic and inorganic characteristics including bacterial cell number, enzyme activity, nutrients, and heavy metals have been monitored in twelve acrylic experimental tanks for two weeks to estimate and compare self-purification capacities in two Korean wet-land environments, tidal flat and rice field, which are possibly different with the environments in other countries because of their own climatic conditions. FW tanks, filled with rice field soils and fresh water, consist of FW1&2 (with paddy), FW3&4 (without paddy), and FW5&6 (newly reclaimed, without paddy). SW tanks, filled with tidal flat sediments and salt water, are SW1&2 (with anoxic silty mud), SW3&4 (anoxic mud), and SW5&6 (suboxic mud). Contaminated solution, which is formulated with the salts of Cu, Cd, As, Cr, Pb, Hg, and glucose+glutamic acid, was spiked into the supernatent waters in the tanks. Nitrate concentrations in supernatent waters as well as bacterial cell numbers and enzyme activities of soils in the FW tanks (except FW5&6) are clearly higher than those in the SW tanks. Phosphate concentrations in the SW1 tank increase highly with time compared to those in the other SW tanks. Removal rates of Cu, Cd, and As in supematent waters of the FW5&6 tanks are most slow in the FW tanks, while the rates in SW1&2 are most fast in the SW tanks. The rate for Pb in the SW1&2 tanks is most fast in the SW tanks, and the rate for Hg in the FW5&6 tanks is most slow in the FW tanks. Cr concentrations decrease generally with time in the FW tanks. In the SW tanks, however, the Cr concentrations decrease rapidly at first, then increase, and then remain nearly constant. These results imply that labile organic materials are depleted in the FW5&6 tanks compared to the FW1&2 and FW3&4 tanks. Removal of Cu, Cd, As from the supernatent waters as well as slow removal rates of the elements (including Hg) are likely due to the combining of the elements with organic ligands on the suspended particles and subsequent removal to the bottom sediments. Fast removal rates of the metal ions (Cu, Cd, As) and rapid increase of phosphate concentrations in the SW1&2 tanks are possibly due to the relatively porous anoxic sediments in the SW1&2 tanks compared to those in the SW3&4 tanks, efficient supply of phosphate and hydrogen sulfide ions in pore wates to the upper water body, complexing of the metal ions with the sulfide ions, and subsequent removal to the bottom sediments. Organic materials on the particles and sulfide ions from the pore waters are the major factors constraining the behaviors of organic/inorganic elements in the supernatent waters of the experimental tanks. This study needs more consideration on more diverse organic and inorganic elements and experimental conditions such as tidal action, temperature variation, activities of benthic animals, etc.