Comparative Investigation of the Urea Degradation in Reservoirs of the Han River System

Osamu Mitamura(三田村緖佐武),Junji Tachibana(橘淳治),Hiroyuki Kamitani(神谷博之),Bomchul Kim(金凡微),Kyu-Song Cho(曺圭松) 강원대학교 환경연구소 1996 環境硏究 Vol.13 No.-

동해안 (東海岸) 기수호에서의 (汽水湖) 요소 및 용존유기탄소 (溶存有機炭素) , 질소 (窒素) , 인에 (燐) 관하여

삼전촌서좌무 (三田村緖左武),조규송 ( Osamu Mitamura,Kyu Song Cho ) 한국하천호수학회 1984 생태와 환경 Vol.17 No.3·4

Distribution of urea and dissolved organic matter were surveyed in the two brackish coastal lagoons, Hwajinpo and Yungrangho in August 1978. Concentration of urea was in the range of 0.5 to 3.9 ㎍-atN/ℓ and showed similar pattern of distribution to that of ammonia. The atomic ratio of dssolved organic carbon and dissolved organic nitrogen to dissolved organic phosphorus was 560 : 70 : 1 in Hwajinpo and 740 : 75 : 1 in Yungrangho. In both of the lagoons salinity did not show significant correlation with urea and dissolved organic matter. In the Yungrangho vertical distribution of dissolved oxygen concentration did not show significant correlation with DOC, DON. and. DOP, either. Comprising 0.15 to 1.37 percent of dissolved organic carbon and 2.9 to 20.9 percent of dissolved organic nitrogen, urea which is very susceptible to biological uptake and depletion as nitrogen source of phytoplankton seems to be an important constituent of, dissolved organic matter in brackish lagoons.

한강수계 (漢江水系) 인공호에서의(人工湖) 요소분해속도 비교연구

삼전촌서좌무 (三田村緖佐武),귤순치,신곡박지 (神谷博之),김범철,조규송 ( Osamu Mitamura,Junji Tachibana,Hiroyuki Kamitani,Bomchul Kim,Kyu Song Cho ) 한국하천호수학회 1995 생태와 환경 Vol.28 No.2

The in situ rate of urea degradation was measured in the euphotic zone of three reservoirs located in the Han River System, The daily rate of urea degradation(i. e., sum of the incorporation rate of urea carbon into the particulate organic matter and the liberation rate of urea carbon into the water as carbon dioxide) in surface water was 14μmol urea·m^-3.day^-1 in Lake Soyang, 43μmol urea ·m^-3.day^-1 in Lake Chungju and 49μmol urea·m^-3.day^-1 in Lake Paldang. There was no change at various depths. The greater part of urea degradation took place during the the phase of carbon dioxide liberation. In the light, an appreciable amount of urea degradation was incorporated into phytoplankton cells, but this was extremely low in the dark condition. High correlation coefficients were obtained between urea degradation rate and photosynthesis or photosynthetic carbon assimilation rate by unit amount of chlorophyll-a. The residence time of urea in surface water was respectively estimated as 9, 2 and 9 days in Lakes Soyang, Chundu and Paldang. The present results suggest that in reservoirs the urea degradation occurred in connection with photosynthetic activity and that its has an important contribution as one of the nitrogen source for phytoplankton population. The brief residence time of urea indicates that the urea is a rapidly recycled from of biogeochemical parameter.

북한강 수계의 댐호수의 생산층에 있어서 요소분해와 회전속도

삼전촌서좌무 (三田村緖佐武),조규송,홍사욱,김해금 ( Osamu Mitamura,Kyu Song Cho,Sa Uk Hong,Hae Keum Lee ) 한국하천호수학회 1989 생태와 환경 Vol.22 No.3

The in situ rate of urea decomposition was measured in the euphotic layer of three reservoirs located in the North Han River System. The urea decomposition rates (as sum of incorporation rate of urea carbon into particulate matter and CO₂ liberation rate into water from urea) in surface waters were 12, 80 and 54 μmol ureaㆍm^(-3) day^(-1), in Lake Soyang, Lake Chuncheon and Lake Euiam. The greater part of urea decomposition took place with the CO₂ liberation into water. High rates of urea carbon incorporation were obtained at surface layer, while low rates were found in lower layer and the dark bottles. The decomposition rate of urea, the carbon incorporation rate, and the CO₂ liberation rate decreased with depth. The vertical distributions of the urea decomposition rate showed similar patterns to those of photosynthesis. The turnover rates of urea in the three reservoirs were calculated respectively as 41, 6.1 and 3.4 days at the surface, and the values increased with depth.

북한강수계 (北漢江水系) 인공호에 있어서 식물플랑크톤에 의한 요소분해와 그 크기 분포

삼전촌서좌무 (三田村緖佐武),조규송,홍사욱,이해금 ( Osamu Mitamura,Kyu Song Cho,Sa Uk Hong,Hae Keum Lee ) 한국하천호수학회 1990 생태와 환경 Vol.23 No.4

The influence of natural phytoplankton cell classes upon the response of urea decomposition was investigated in four reservoirs - Lakes Paro, Chuncheon, Soyang and Uiam - in the North Han River System. The decomposition rate of urea was 0.3 to 29.4 μ㏖ urea m^(-3) · hr.^(-1) in the light and 0.2 to 14.9 μ㏖ urea · m^(-3)·hr.^(-1) in the dark. Much higher decomposition rates were observed at the eutrophic stations in Lake Uiam. The urea decomposition in the smaller fraction (<5 ㎛) exceeded that in the middle (5∼25 ㎛) and the larger fraction (>25㎛). No differences in the ratios of urea decomposition to chlorophyll-a or photosynthesis among three fractions were observed. These trends were no different between sampling areas and reservoirs. This may be mainly due to the difference in the standing crop of phytoplankton. The greater part of urea decomposition was the phase of the CO₂ liberation rate into water. 8 to 50% of the urea decomposition was incorporated into the particulate phase in the light, but this was much lower in the dark. A close relationship between urea decomposition and chlorophyll-a or photosynthesis was observed in the three fractions, which have high correlation coefficients. The results of the present study indicate that urea in reservoirs decomposes by phytoplankton rather than bacteria, and thus phytoplankton is more competitive than bacteria.

한강수계의 (漢江水系) 주요용존화학성분에 (主要溶存化學成分) 관한 조사

홍사욱,중정신지 (中井信之),삼전촌서좌무 (三田村緖佐武) ( Sa Uk Hong,Nobuyuki Nakai Osamu Mitamura ) 한국하천호수학회 1982 생태와 환경 Vol.15 No.3·4

In this study the changes of the dissolved chemcal components in the water of Han River were investigated. Total 32 sampling sites were choosen from the upper part of South Han River and North Han River to the lower dart of main Han River near Kimpo Bridge. Sampling was done 3 times on November, 1980 and during May to October, 1981, respectively. Because of the mine waste and Lime stone zone the water from the upper part of South Han River showed high value of T-hardness, Ca-hardness, SO₄ and pH. Furthermore, the several tributries of this arears where recieved the mine waste water showed even higher T-hardness, Ca-hardness and pH values. The values of T-hardness, Ca-hardness, SO₄ and pH of the North Han River were relatively lower than that of the South Han River, however, the both values of T-hardness and pH of Hwacheon and Chuncheon reservoir showed the tendency toward increasing in comparison to the other sites of North Han River. On the other hand, PO₄-P and N-compound were both detected in a very small amount in the water from South and North Han HanRiver while the DO was saturated in the water. From this results, it can be suggested that South and North Han River are not polluted yet and reasonably clean until now. However, from the vicinity of the 3rd Han RiverBridge to the Kimpo Bridge area of the main Han River DO value of water was significantly decreased while the value of Cl, PO₄-P and N-compound were markedly increased, suggesting that the water of this area was severely polluted because of the influence of urban waste water.

Urea Docomposition and its turnover Time in Euphotic Layer of Reservoires in the North Han Hiver System

삼전촌서좌무,조규송,홍사욱,이해금 江原大學校 附設 環境硏究所 1989 環境硏究 Vol.6 No.-

The in situ rate of urea decomposition was measured in the euphotic layer of three reservoirs located in the North Han River System. The urea decomposition rates (as sum of incorporation rate of urea carbon into particulate matter and CO_(2) liberation rate into water from urea) in surface waters were 12, 80 and 54 μmol urea · m^(-3) day^(-I), in Lake Soyang, Lake Chuncheon and Lake Euiam. The greater part of urea decomposition took place with the C0_(2) liberation into water. High rates of urea carbo incorporation were obtained at surface layer, while low rates were found in lower layer and the dark bottles. The decomposition rate of urea, the carbon incorporation rate, and the CO_(2) liberation rate decreased with depth. The vertical distributions of the urea decomposition rate showed similar patterns to those of photosynthesis. The turnover rates of urea in the three reservoirs were calculated respectively as 41,6.1 and 3.4 days at the surface, and the values increased with depth. 북한강수계 3개 인공호수의 생산층에 있어서 현장법으로 요소 분해속도를 측정했다. 요소분해속도(요소에서 유래도는 탄소가 수중생물로 흡수되는 량과 이산화탄소로서 수중에 방출되는 량의 합)는 소양호, 춘천호 및 의암호의 표층수에서 각각 12, 80, 54μmol Urea m^(-3)·day^(-1)였다. 요소 분해는 대부분이 이산화탄소 형태로 수중에 방출된다. 요소태탄소의 흡수속도는 표층에서 높은 값이 관찰됐으나 생산층의 하층 및 암조건에서는 낮았다. 요소분해속도, 요소태탄소의 흡수속도 및 이산화탄소의 방출 속도는 깊이에 따라 감소됐다. 요소분해속도와 광합성의 수직분포는 유사하였다. 각 호수의 표층수에 있어서 회전시간은 소양호, 춘천호 및 아ㅢ암호에서 4.1, 6.1 및 3.41일로 계산되며 이 값은 깊이에 따라 증가됐다.