• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.27 no.4
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• pp.173-193
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• 2022

Dissolved nutrients in seawater are a key variable for understanding the role of the ocean in controlling atmospheric carbon dioxide, which is a major cause of global warming. In order to continuously monitor changes in the marine environment in the waters around the Korean Peninsula, dissolved nutrient data are being measured through regular observations by national institutions and various research projects. To increase the utilization of these data, the Jurisdictional Ocean Information Sharing System (JOISS), which integrates data from each institution, was established. In this study, for the dissolved nutrient data of JOISS, primary quality control was performed using the regional dissolved nutrient concentration range in the waters around the Korean Peninsula, and the correlation between the dissolved nutrient and other oceanographic characteristics or the correlation within dissolved nutrient components. Providing the quality control flags of regional range and primary quality control may increase the reliability of JOISS dissolved nutrient data and promote the utilization of dissolved nutrient data in JOISS. In addition, we proposed a secondary quality control method essential for improving the international comparability of JOISS dissolved nutrients.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.spc
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• pp.47-50
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• 2009

Nutrient losses, especially nitrogen and phosphorus, in agricultural runoff can contaminate surface and ground water, leading to eutrophication. Thus, erosion control is crucial to minimizing nutrient losses from agricultural land. Assessments of various erosion control practices were carried out under various cropping system, soil management practices, and slope conditions by means of a lysimeter study and under artificial rainfall. Soil and nutrient losses were monitored in a small agricultural field to evaluate the soil conservation practices. Nutrient losses occur in runoff and leachate (dissolved nutrient) and in sediments (particulate nutrient). Dissolved nitrates accounted for the majority (about 90%) of nitrate transport within the soil. Particulate phosphate in sediments represented the majority (60% to 67%) of phosphate transport. Recently, engineering and agronomic erosion-control practices haver been used to reduce erosion problems in fields on slopes. These practices reduced soil loss, runoff, and nutrient loss to 1/6, 1/2,and 1/3 their original levels, respectively. Bioavailable particulate phosphate in sediments represents a variable but longterm source of phosphate for algae. Dissolved nitrate and phosphate are immediately available for algal uptake, so reducing fluxes of these nutrients should also reduce the risk of eutrophication.

• Environmental Engineering Research
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• v.15 no.1
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• pp.41-48
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• 2010

This paper describes the influence of nutrient salts eluted from the bottom of a closed water area where polluted sediment has been deposited by inflowing river water. The elution pattern was monitored at our experimental facility. Both the sediment pore water and water above the bottom were sampled using a dialyzer sampler (peeper). The pore water of the eutrophicated sediment contained a large amount of nutrient salts, and the effect of elution was confined to a limited area of the bottom surface. The nutrient concentration of the sediment pore water was closely related to both the water temperature and dissolved oxygen (DO) concentration. The eluted nutrients from the sediment provided a source for phytoplankton and algae growth. This experimental data indicated that the water quality of the surface was not directly connected to the eluted nutrient salts, while it was indirectly affected by the total ecosystem, including all the organisms within an area and their environment.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.4
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• pp.372-381
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• 2014

We investigated cause of non-outbreak of Cochlodinium polykrikoides blooms in the western coast of Jaran Bay during Summer, 2013, by combining chemical field data and physiological data of C. polykrikoides, which had been already published. The predominant species were mainly diatoms, and dominant species was Cerataulina pelagica, Chaetoceros spp., Navicula spp. and Nitzschia spp.. In case of dissolved inorganic nutrients in the western coast of Jaran Bay, dissolved inorganic phosphorus (DIP) was similar to that in previous outbreak period of C. polykrikoides blooms, but dissolved inorganic nitrogen (DIN) was lower. C. polykrikoides might be disadvantageous in competition with diatom species because half-saturation constants (Ks) of C. polykrikoides for inorganic nutrients was lower than those of diatoms. Also, the western coast of Jaran Bay, where DIN concentration is relatively low, was an unfavorable environment for growth of C. polykrikoides characterized by nitrogen dependence. Therefore, C. polykrikoides which have the disadvantageous position for competition of inorganic nutrient might have been suppressed by diatom blooms under environment of low nutrient in the western coast of Jaran Bay.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.459-468
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• 2022

Long-term data analyses and bioassay experiments were conducted to assess limiting nutrients in Cheonsu Bay and Taean sea. First, long-term nutrient data (2004-2016) provided by the National Water Quality Monitoring Network were used to assess potential limiting nutrients. Analysis of the long-term data showed that the dissolved inorganic nitrogen/dissolved inorganic phosphate (DIN/DIP) ratio was mostly below 16, with N limitation being dominant. A subsequent analysis using the concentration ratios of N, P, and Si showed that N limitation was dominant during summer and autumn but that Si limitation occasionally occurred during winter and spring in relatively limited areas. However, the dominant limiting nutrient was not determined. The nutrient analysis of the field water collected during the bioassay experiment showed that DIN/DIP revealed P limitation at all stations in March and May, whereas N limitation was dominant in July and October. In the analysis using the concentration ratios of N, P, and Si, P and Si limitation appeared in March and May, but there were points with no dominant limiting nutrient. However, N limitation was dominant in July and October. In the bioassay experiment for assessment of the actual limiting nutrient, the results showed no specific limiting nutrient in March, whereas NH₄⁺ and NO₃^- showed responses in May, July, and October, which confirmed that N was a substantial limiting nutrient directly involved in phytoplankton growth during this period.

• Journal of the korean society of oceanography
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• v.39 no.1
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• pp.14-19
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• 2004

Difference of Dissolved Inorganic Phosphorus (DIP), Dissolved Inorganic Nitrogen (DIN) and Dissolved Silicate (DSi) budgets in the Bohai Sea between 1982 and 1992 related the decrease of the Yellow River discharge is discussed on the basis of observed data. The estuarine circulation in the Bohai Sea had been weakened from 1982 to 1992 due to the decrease of the Yellow River discharge and the average residence time of fresh water had become longer. DIN concentration increased but DIP and DSi concentrations decreased from 1982 to 1992 in the Bohai Sea. Primary production was regulated mainly by water temperature and DIN concentration in 1982 but it was regulated mainly by DIP concentration in 1992. Primary production was larger than decomposition plus bottom release and nitrogen fixation was larger than denitrification in 1982. However, decomposition plus bottom release was larger than primary production and denitrification was larger than nitrogen fixation in 1992 in the Bohai Sea.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.2
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• pp.90-103
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• 2014

Distribution characteristics of water masses, dissolved inorganic and organic nutrients were investigated in the southern part of the East Sea of Korea in September, 2011. On the basis of the vertical profiles of temperature, salinity and dissolved oxygen, water masses in the study area were divided into 4 major groups, such as WM (water mass)-I, WM-II, WM-III, WM-IV. Their characteristics were similar to Tsushima Surface Water (TSW), Tsushima Middle Water (TMW), North Korea Cold Water (NKCW) and East Sea Proper Water (ESPW), respectively. In the vertical profiles of dissolved nutrients, dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) concentrations were highest in the WM-IV, followed by WM-III, WM-II, WM-I. On the contrary, distribution of dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) were highest in the WM-I, followed by WM-II, WM-III, WM-IV. Although the DIN : DIP ratio in all of the water masses was similar to Redfield ratio(16), the DIN : DIP ratio in mixed layer was about 5.3, indicating that inorganic nitrogen is the limiting factor for the growth of phytoplankton. However, the DON proportion in dissolved total nitrogen (DTN) was about 70% in the mixed layer where inorganic nitrogen is limiting factor. Thus, enriched DON may play an important source of the nutrient for the growth of phytoplankon in the East Sea.

• Journal of Environmental Science International
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• v.7 no.6
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• pp.817-825
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• 1998

A three-dimensional ecosystem model is applied to the Suyoung Bay, located at the southeastern part of Korea, to study of the material distribution in the time scale of several tens days. The model has included of the DIN(Dissolved Inorganic Nitrogen), DIP(Dissolved Inorganic Phosphate), phytoplankton, zooplankton and detritus, and also was coupled with the physical processes. The spatial distribution of chlorophyll-a and primary productivity in the model is determined by the physical and chemical-biological parameters. The horizontal distributions of the DIN, DIP and chlorophyll-a are decreased from the coast to the off-shore, though the nutrients show some more complicated pattern than the chlorophyll-a. The nutrient contents in the off-shore are low, and thus a relatively low productivity(chlorophyll-a) are presented. On the whole, the distribution of the results of model are smoother than the observed ones and some small scale variation in the observed data cannot be reproduced by the model due to the resolution limits of model. However, the basic pattern and the quantitavities has been reproduced by the model well.

• Ocean and Polar Research
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• v.32 no.3
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• pp.291-297
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• 2010

In the summer of 2008 (August 4-14), vertical and horizontal distributions of inorganic nutrients and dissolved organic carbon (DOC) were measured in the southwestern East Sea. Concentrations of DOC were determined for the first time in the southwestern East Sea using the high-temperature combustion oxidation (HTCO) method, and results were compared with those measured by another laboratory. Concentrations of DOC ranged from 58 to 104 ${\mu}M$ in the upper 200 m, showing a typical decreasing pattern with depth. Generally, concentrations of DOC were relatively lower, with higher nutrient concentrations, in the upper layer of the coastal upwelling zone. Concentrations of DOC ranged from 54 to 64 ${\mu}M$ in the deep Ulleung Basin (200-1500 m), and were higher than those in the Pacific and Atlantic oceans. In association with rapid vertical ventilation of the euphotic, this difference indicates a larger accumulation of semi-labile DOC in the deep East Sea than in the major oceans. A correlation between apparent oxygen utilization (AOU) and DOC in the deep ocean of the East Sea revealed that only a small portion (<10%) of the sinking DOC, relative to the sinking particulate organic carbon (POC), contributes to microbial degradation. Our results present an important data set of DOC in the East Sea, which plays a critical role in carbon cycle modeling and sequestration.

• Journal of Korean Society on Water Environment
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• v.39 no.1
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• pp.87-101
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• 2023

The constituents of a watershed control a wide range of ecosystem processes, such as, carbon sequestration, nutrient retention, and biodiversity preservation. Maintenance of a healthy watershed is advantageous to humans in many direct and indirect ways. Dissolved organic matter fluorescence analysis is one of the most commonly utilized parameters for water quality measurement, pollution source tracking, and determination of the ecological state of a watershed. Throughout the recent decades, the advancement in data processing, instrumentation, and methods has resulted in many improvements in the area of watershed study with fluorescence analysis. The current trend of coupling advanced instrumentations and new comparative parameters, such as, microplastics of different types, antibiotics, and specific bacterial contaminants have been reported in watershed studies. However, conventional methodologies for obtaining fluorescence excitation emission matrices and for calculating the fluorescence and spectral indices are preferred to advanced methods, due to their easiness and simple data collection. This review aims to gain a general understanding of the use of dissolved organic matter fluorescence analysis for diagnosis and source identification of watershed pollutions, by focusing on how the studies have utilized fluorescence analysis to improve existing knowledge and techniques in recent years.