• Ocean and Polar Research
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• v.34 no.2
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• pp.229-237
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• 2012

Using results from an Earth System model, we investigated change in primary production in the East China Sea, under a global warming scenario. As global warming progresses, the vertical stratification of water becomes stronger, and nutrient supply from the lower part to the upper part is reduced. Consequently, so is the primary production. In addition to the warming trend, there is strong decadal to interdecadal scale variability, and it takes a few decades before the warming trend surpasses natural variability. Thus, it would be very hard to investigate the global warming trend using data of several years' length.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.512-513
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• 2003

Human activities have become a major factor that significantly changes the global environment. Mankind has increasingly used land, water, minerals and other natural resources since the beginning of industrialization, and future growth in the population and economy is thought to further enhance the impact upon the Earth. The global climate, biogeochemical process and natural ecosystems are closely linked with one another, and changes in any one of these systems may effect the others, which could result in consequences detrimental to humans and other living organisms on the Earth.(omitted)

• Journal of environmental and Sanitary engineering
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• v.11 no.3
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• pp.9-12
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• 1996

Polychlorinated biphenyl (PCBs) is one of major toxic pollutants in marine environments, This artificial chlorinated compound has been found in freshwater, seawater, soil, sediments and organismes living in various environments. Because of its toxicity and degradability, its uses in industrial processes have been banned after 1984 in Korea. Coastal area is an important environment for agriculture, industry, transportation, reduction of pollution loads through biogeochemical processes, cycling of nutrients and recreation. Input of pollutants from land and freshwater has been occurring through runoff, rivers and estuaries. Concentrations of PCBs were determined with GC-ECD. Concentrations of PCBs were in the range of 1.0 - 19.2 ng/g-dry weight of sediment(g-d.w.) at Ulsan, 4.5 -8,2 ng/g-d.w. at Onsan, 2.7 - 33.5 ng/g-d.w. at Masan and 4.0 - 60.7 ng/g-d.w. in Kwangyang, In Inchon area, PCBs were not detected in sediments. In sediments of Nakdong estuary, the distribution of PCBs' concentrations was 0.19 - 303 ng/g-d.w.

• Proceedings of the Zoological Society Korea Conference
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• 1995.10b
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• pp.88-88
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• 1995

Microorganism are centIal core to biosphere sm1ainablity and biogeochemical cycles on this earth. Most of food, medical and pabamceutical new materials through biotechnology are derived from many kinds of microorganisms. Microorganisms are important resources of biotechnology. Beside these, micorbial diversity is key to explore the frontiers of knowledge about the strategies and limits of life. Through the micorotganisms, we can monitor the environmental changes and conditions. Moreover, the microorganismsms play a role in conservation and restoration of higher plants and animals. And we can get a lot of ecological, evolutionary knowledges from microbial models. In spite of these importances, the microbial diversity is not properly evaluted because of their unculturablity. Only 0.001 - 3 % of total bacteria in natural habitats are cultumble and the rest are viable but uncultumble. Only 3,100 species are listed up in the Bergey's Manual. Considering the symbisis and estimated numbers of insect are more than 800,000, the symbiotic microorganisms are about 1,000,000 species. Recently, by using the genetic and molecular technics, the microbial diversity is now unveiled. In this symposium, the genetic, species and ecological diversity will be given. given.

• Ocean and Polar Research
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• v.43 no.4
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• pp.353-363
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• 2021

Fluorescent dissolved organic matter (FDOM) is referred to organic matter which absorbs efficiently solar radiation energy and fluorescence in the water column. The component and molecular structure of marine organic matter can be changed depending on the various substances and origins of organic matter, and then the organic matter has unique fluorescent properties. As the cutting-edge analytical techniques of optical measurement continuously developing from last few decades, a study on FDOM has been applied as a biogeochemical tracer to quantify the organic matter concentration and to investigate the behaviors and origins of organic matter. Especially, the marine environment around the Korean Peninsula is an ideal research area to study FDOM because of various oceanographic characteristics and the origins of organic matter. This study describes the general properties of FDOM and introduces the cycling and behaviors of marine organic matter based on the domestic research studies.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.413-413
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• 2023

Wetlands are a critical component of the global carbon cycle and are essential in mitigating climate change. Accurately quantifying wetland carbon emissions is crucial for understanding and predicting the impact of wetlands on the global carbon budget. The uncertainty quantifying carbon in wetlands may comes from the ecosystem's hydrological, biochemical, and microbiological variability. The Community Land Model is a sophisticated and flexible land surface model that offers several configuration options such as energy and water fluxes, vegetation dynamics, and biogeochemical cycling, necessitating careful consideration for the alternative configurations before model implementation to develop a practical model framework. We conducted a systematic literature review, analyzing the alternatives, focusing on the carbon stock pools configurations and the parameters with significant sensitivity for carbon quantification in wetlands. In addition, we evaluated the feasibility and availability of in situ observation data necessary for validating the different alternatives. This analysis identified the most suitable option for our study site, the Binbong Wetland, in Korea.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.2 no.2
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• pp.53-68
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• 1997

Lake Shihwa, artificially constructed since 1988, shows a typical two-layered system depending on strong haline density stratification. Sill of the water gate at 6 m depth greatly restricts physical mixing with outer seawater and circulation in the lake, and contributes to the enhancement of anoxic environment in the deeper layer. With this enclosed physical environment, Lake Shihwa receives enormous amounts of organics, ammonia, and other pollutants from the neighboring municipal and industrial complexes through six major streams, thus developing biogeochemical differentiation of anoxic to suboxic environment in the high saline bottom water and highly eutrophicated brackish surface water. This study investigated vertical structures, biogeochemical behaviors and processes of various organic and inorganic compounds around oxic-anoxic interface. Nitrite and nitrate rapidly decreased below the pycnocline where about $1{\times}10^8$ tons of hypoxic bottom water exist. In this bottom layer, ammonium ranged from 75 to 360 ${\mu}M$ mainly resulting from deamination of dissolved organic nitrogen and ammonification of precipitated organic particles. Despite large amounts of surface water discharge and dilution by outer seawater inflow about $3{\times}10^8$ tons from April to August, 1996, bottom layer did not show any improvement of water quality and maintained highly reduced environment. The main reason seems to be imbalance between ineffectiveness of dilution due to shallow depth and large surface area, overloaded POC influx from the eutrophicated surface biological activity, and poor replenishment of oxygen in this artificial lake system. Therefore, as long as current salinity dependent two-layered system maintains with its physical limitations, any improvement of water quality cannot be foreseen in Lake Shihwa.

• Korean Journal of Ecology and Environment
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• v.36 no.4 s.105
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• pp.434-446
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• 2003

The fate and transport of many trace metals, metalloids, and radionuclides in porous media is closely linked to the biogeochemical reactions that occur as a result of organic carbon being sequentially degraded by different microorganisms using a series of terminal electron acceptors. The spatial distribution of these biogeochemical reactions is affected by processes that are often unique and/or characteristic to a specific environment. Generic model formulations have been developed and applied to simulate the fate and transport of arsenic in two hydrologic settings, permanently flooded freshwater sediments, namely non-vegetated wetland sediments and vegetated wetland sediments. The key physical processes that have been considered are sedimentation, effects of roots on biogeochemistry, advective transport, and differences in mixing processes. Steady-state formulations were applied to the sedimentary environments. Results of numerical simulations show that these physical processes significantly affect the chemical profiles of different electron acceptors, their reduced species, and arsenate as well as arsenite that will result from the degradation of an organic carbon source in the sediments. Even though specific biological transformations are allowed to proceed only in zones where they are thermodynamically favorable, the results show that mixing as well as abiotic reactions can make the profiles of individual electron acceptors overlap and/or appear to reverse their expected order.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.1
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• pp.66-77
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• 2005

We have investigated microclimatic controls on the spatiotemporal variations of net primary production (NPP) of a rugged forested watershed using the process-based biogeochemical model (BIOME-BGC). To validate the model simulation of water and carbon cycles at the plot scale, we have conducted field survey over deciduous broadleaf forest (DBF) and evergreen needleleaf forest (ENF) since 2000. The modeled values of soil temperature, soil moisture and soil respiration showed high correlation with those from the field measurements. The modeled seasonal changes of NPP showed high correlation with air temperature but no significant correlation with water related parameters. The precipitation frequency turned out to be the best climatic factor to explain the annual variation of NPP. Furthermore, NPP of ENF was more sensitive to precipitation frequency than that of DBF. With changes in vegetation cover and topography, the spatial distribution of NPP was of great heterogeneity, which was negatively correlated with the magnitude of NPP. Despite the annual precipitation of 1,400mm, NPP at the study site was constrained by the amount of water available for the vegetation. Such a modeling result should be verified by the field measurements.

• Journal of the Korean earth science society
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• v.28 no.1
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• pp.112-122
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• 2007

It is known that coal-derived fly ashes have the unique chemical composition and mineralogical characteristics. Since iron oxides in coal fly ash are enriched with heavy metals, the subsurface media including soils, underground water, and sea water are highly likely contaminated with heavy metals when the heavy metals are leached from fly ashes by water-fly ash interactions. The purpose of this study was to investigate how indigenous bacteria affect heavy metal leaching and mineralogy in fly ash slurry during the fly ash-seawater interactions in the ash pond located in Dangjin seashore, Korea. The average pH of ash pond seawater was 8.97 in nature. Geochemical data showed that microbial activity sharply increased after the 7th day of the 60-day course batch experiments. Compared with other samples including autoclaved and natural samples, ${SO_4}^{2-}$ was likely to decrease considerably in the fly ash slurry samples when glucose was added to stimulate the microbial activity. Geochemical data including Eh/pH, alkalinity, and major and trace elements showed that the bacteria not only immobilize metals from the ash pond by facilitating the chemical reaction with Mn, Fe, and Zn but may also be able to play an important role in sequestration of carbon dioxide by carbonate mineral precipitation.