Chikahide Komura, T. Hama, Yukihiro Ichinose, T. Kubota
The water quality of the river basins situated in volcanic areas and exposed to volcanic activity can be affected by the acidic water, resulting in the pollution of surface water. On April 19th, 2018, the first eruption in 250 years of Mt. Iou, one of the Kirishima volcanos, caused the discharge of mud and acidic water into the Nagae River, contaminating the water with arsenic at a high concentration that exceeded the environmental standard （ 10 µg L -1 ） . In this study, we investigated the changes in arsenic concentration in the streamflow process, the relationship between pH and Electrical Conductivity （ EC ） , and the runoff characteristics through a continuous observation. The results indicate that the river water was diluted and improved during the streamflow process owing to dilution as a result of influx of water from tributaries, the arsenic concentration has a correlation with pH and EC, particularly, in the upstream area and on nonrainy days, and the arsenic concentration correlates with iron, aluminum, and manganese concentrations. Consequently, arsenic accumulates at the bottom of the riverbed on nonrainy days, and its concentration becomes high owing to the resuspension of the river sediment on rainy days.
地处火山地区、受火山活动影响的河流流域的水质会受到酸性水的影响，造成地表水的污染。2018年4月19日，雾岛火山之一的Iou火山250年来首次喷发，导致泥浆和酸性水排放到长江中，砷的浓度超过了环境标准(10 μ g L -1)。本研究通过连续观测研究了径流过程中砷浓度的变化、pH值与电导率(EC)的关系以及径流特征。结果表明:在径流过程中，由于支流水的冲淡，河水被稀释并得到改善;砷浓度与pH和EC存在相关性，特别是在上游地区和非阴雨天;砷浓度与铁、铝、锰浓度存在相关性。因此，在非雨天，砷在河床底部积聚，在雨天，由于河流沉积物的再悬浮，砷的浓度变得很高。
{"title":"Arsenic Pollution in Nagae River after Volcanic Eruption of Mt. Iou","authors":"Chikahide Komura, T. Hama, Yukihiro Ichinose, T. Kubota","doi":"10.2965/JSWE.44.43","DOIUrl":"https://doi.org/10.2965/JSWE.44.43","url":null,"abstract":"The water quality of the river basins situated in volcanic areas and exposed to volcanic activity can be affected by the acidic water, resulting in the pollution of surface water. On April 19th, 2018, the first eruption in 250 years of Mt. Iou, one of the Kirishima volcanos, caused the discharge of mud and acidic water into the Nagae River, contaminating the water with arsenic at a high concentration that exceeded the environmental standard （ 10 µg L -1 ） . In this study, we investigated the changes in arsenic concentration in the streamflow process, the relationship between pH and Electrical Conductivity （ EC ） , and the runoff characteristics through a continuous observation. The results indicate that the river water was diluted and improved during the streamflow process owing to dilution as a result of influx of water from tributaries, the arsenic concentration has a correlation with pH and EC, particularly, in the upstream area and on nonrainy days, and the arsenic concentration correlates with iron, aluminum, and manganese concentrations. Consequently, arsenic accumulates at the bottom of the riverbed on nonrainy days, and its concentration becomes high owing to the resuspension of the river sediment on rainy days.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82347515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this research, the performance characteristics of the multilayered filtration bed （ MLF ） and non-multilayered filtration bed （ n-MLF ） in a pilot-scale multistage constructed wetland for treating sewage were compared, and the effect of the multilayered structure on the water purification performance was elucidated. It was confirmed that the effect of the multilayered structure on the aerated treatment performance of, for example, BOD and NH 4+ -N removal was negligible under the vertical flow condition, but not under the hybrid condition comprising both vertical and horizontal flows. MLF was easier to become anaerated than n-MLF, resulting in a lower aerated treatment performance under the hybrid condition. Furthermore, the effect of a lack of vegetation on MLF manifested as a lower nitrogen removal performance. Although the specific removal unit for BOD and phosphorus under the vertical flow condition in MLF increased 1.5fold compared with that in n-MLF, the removal performance of nitrogen could not be improved. The specific energy consumption for sewage treatment by the constructed wetland in this work was low at 0.32 kWh m -3 , demonstrating the effectiveness of the constructed wetland in accomplishing the decarbonization of sewage works.
本研究在中试多级人工湿地中比较了多层过滤床(MLF)和非多层过滤床(n-MLF)处理污水的性能特点，并阐明了多层结构对水净化性能的影响。结果表明，在垂直流动条件下，多层结构对BOD和nh4 + -N去除等曝气处理性能的影响可以忽略不计，但在垂直和水平混合流动条件下则不能忽略。混合条件下，MLF比n-MLF更易曝气，导致曝气处理性能较差。此外，缺乏植被对MLF的影响表现为较低的脱氮性能。垂直流动条件下，MLF对BOD和磷的比去除率比n-MLF提高了1.5倍，但对氮的去除率没有提高。本工程人工湿地处理污水的比能耗较低，为0.32 kWh m -3，说明人工湿地在完成污水工程脱碳方面的有效性。
{"title":"Effect of Multilayered Structure of Filtration Beds on Sewage Treatment Performance in a Multistage Constructed Wetland","authors":"Tasuku Suzuki, T. Taniguchi, K. Nakano","doi":"10.2965/jswe.44.85","DOIUrl":"https://doi.org/10.2965/jswe.44.85","url":null,"abstract":"In this research, the performance characteristics of the multilayered filtration bed （ MLF ） and non-multilayered filtration bed （ n-MLF ） in a pilot-scale multistage constructed wetland for treating sewage were compared, and the effect of the multilayered structure on the water purification performance was elucidated. It was confirmed that the effect of the multilayered structure on the aerated treatment performance of, for example, BOD and NH 4+ -N removal was negligible under the vertical flow condition, but not under the hybrid condition comprising both vertical and horizontal flows. MLF was easier to become anaerated than n-MLF, resulting in a lower aerated treatment performance under the hybrid condition. Furthermore, the effect of a lack of vegetation on MLF manifested as a lower nitrogen removal performance. Although the specific removal unit for BOD and phosphorus under the vertical flow condition in MLF increased 1.5fold compared with that in n-MLF, the removal performance of nitrogen could not be improved. The specific energy consumption for sewage treatment by the constructed wetland in this work was low at 0.32 kWh m -3 , demonstrating the effectiveness of the constructed wetland in accomplishing the decarbonization of sewage works.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76337038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Characteristics of Disinfection By-products in Effluents from Wastewater Treatment Plants in Kyoto City","authors":"K. Hosoda, T. Segawa","doi":"10.2965/jswe.44.103","DOIUrl":"https://doi.org/10.2965/jswe.44.103","url":null,"abstract":"","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80701320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shunsuke Komuro, T. Kitamura, Takao Oouchi, E. Masunaga, Daiki Asaoka, K. Ayukawa, Yasuhide Mikami, Y. Seike, Miyuki Yuzawa, T. Fukushima
Detailed distributions of oxygen-deficient water were observed using a high-resolution tow-yo instrument, YODA Profiler, in Lake Kitaura to investigate the formation of oxygen-deficient water. The results of observations showed that oxygen-deficient water widely appeared at a depth of deeper than 4 m, and the dissolved oxygen （ DO ） concentration in deep areas was particularly low. Furthermore, it was suggested that high phosphorus （ PO 4 -P ） concentrations were eluted from sediments in areas of oxygen-deficient water. The DO concentration at 10 cm above the lake bottom tended to be lower than that at 50 cm above the lake bottom. The oxygen-deficient water in Lake Kitaura is greatly affected by the water depth, which implies that the ratio of the area of oxygen-deficient water can be inferred by lake bathymetry and observed DO profiles. The area of oxygen-deficient water reached 55.9 ％ at 50 cm above the bottom and 63.2 ％ at 10 cm above the bottom of the total area of Lake Kitaura.
{"title":"Distribution of Oxygen-Deficient Water and Estimation of Its Area in Lake Kitaura","authors":"Shunsuke Komuro, T. Kitamura, Takao Oouchi, E. Masunaga, Daiki Asaoka, K. Ayukawa, Yasuhide Mikami, Y. Seike, Miyuki Yuzawa, T. Fukushima","doi":"10.2965/jswe.44.157","DOIUrl":"https://doi.org/10.2965/jswe.44.157","url":null,"abstract":"Detailed distributions of oxygen-deficient water were observed using a high-resolution tow-yo instrument, YODA Profiler, in Lake Kitaura to investigate the formation of oxygen-deficient water. The results of observations showed that oxygen-deficient water widely appeared at a depth of deeper than 4 m, and the dissolved oxygen （ DO ） concentration in deep areas was particularly low. Furthermore, it was suggested that high phosphorus （ PO 4 -P ） concentrations were eluted from sediments in areas of oxygen-deficient water. The DO concentration at 10 cm above the lake bottom tended to be lower than that at 50 cm above the lake bottom. The oxygen-deficient water in Lake Kitaura is greatly affected by the water depth, which implies that the ratio of the area of oxygen-deficient water can be inferred by lake bathymetry and observed DO profiles. The area of oxygen-deficient water reached 55.9 ％ at 50 cm above the bottom and 63.2 ％ at 10 cm above the bottom of the total area of Lake Kitaura.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73227444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fish mortality was investigated in a shallow, constantly stored-water-type regulating pond located in a cold region in mid-March 2018 after ice had melted. In general, fish mortality occurs when water temperatures increase; however, in this case, it occured under freezing conditions. In this study, we attempted to understand the actual water quality by referring to the results of water quality surveys conducted throughout the year and the factors leading to the accident. The studied pond is eutrophic with treated wastewater. Phytoplankton proliferated during the non-freezing season by consuming nutrients in the treated wastewater, and organic matter derived from the phytoplankton accumulated as bottom mud. In early March 2018, the dissolved oxygen (DO) concentration in the bottom layer was almost 0 mg L, while it was also under 1.2 mg L in the upper layer. Concurrently, NH4-N leached out from the reduced bottom mud, and its concentration in the bottom layer increased to 25.4 mg L. The pH of the bottom layer increased to 8.96, and the free ammonia concentration was estimated to be about 3.0 mg L. These results indicate that the low DO and elevated NH4-N concentrations under freezing conditions directly caused this fish mortality incident.
{"title":"Factor Analysis of Seasonal Fluctuations in Water Quality and Fish Mortality Events within Shallow Eutrophic Water under Freezing Conditions","authors":"Morio Tsuji, Masaki Suzuki","doi":"10.2965/jswe.44.165","DOIUrl":"https://doi.org/10.2965/jswe.44.165","url":null,"abstract":"Fish mortality was investigated in a shallow, constantly stored-water-type regulating pond located in a cold region in mid-March 2018 after ice had melted. In general, fish mortality occurs when water temperatures increase; however, in this case, it occured under freezing conditions. In this study, we attempted to understand the actual water quality by referring to the results of water quality surveys conducted throughout the year and the factors leading to the accident. The studied pond is eutrophic with treated wastewater. Phytoplankton proliferated during the non-freezing season by consuming nutrients in the treated wastewater, and organic matter derived from the phytoplankton accumulated as bottom mud. In early March 2018, the dissolved oxygen (DO) concentration in the bottom layer was almost 0 mg L, while it was also under 1.2 mg L in the upper layer. Concurrently, NH4-N leached out from the reduced bottom mud, and its concentration in the bottom layer increased to 25.4 mg L. The pH of the bottom layer increased to 8.96, and the free ammonia concentration was estimated to be about 3.0 mg L. These results indicate that the low DO and elevated NH4-N concentrations under freezing conditions directly caused this fish mortality incident.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87515801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Relationship between Potassium Permanganate Consumption and Total Organic Carbon in Bath Water in Public Bathhouses and Similar Facilities","authors":"Akira Oshima","doi":"10.2965/jswe.44.175","DOIUrl":"https://doi.org/10.2965/jswe.44.175","url":null,"abstract":"","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84950586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The concentrations of cyanamide in environmental water have not been reported owing to a lack of its analytical method. We have developed an analytical method for detecting cyanamide in river water and sea water, which includes the derivatization of cyanamide into dansyl-cyanamide, clean-up with a silica gel solid-phase extraction cartridge, and measurement by liquid chromatography/tandem quadrupole mass spectrometry （ LC-MS/MS ） . The method was applied to the determination of cyanamide concentration in river water at nine different locations in Osaka Prefecture. Cyanamide was detected at all locations, and its concentration ranged from a value below the method detection limit （ MDL ） to 4.2 ng mL -1 . The concentrations were much lower than the registration standards of agricultural chemicals concerning prevention of damage to aquatic flora and fauna （ 670 ng mL -1 ） , and thus, the risk of cyanamide pollution to aquatic flora and fauna in the rivers was assumed to be negligible.
由于缺乏分析方法，环境水体中氰胺的浓度尚未见报道。我们建立了一种检测河水和海水中氰酰胺的分析方法，该方法包括将氰酰胺衍生为丹酰氰酰胺，用硅胶固相萃取筒进行净化，并通过液相色谱/串联四极杆质谱(LC-MS/MS)进行测定。将该方法应用于大阪府9个不同地点河水中氰胺浓度的测定。在所有地点均检测到氰胺，其浓度范围为低于方法检测限(MDL)至4.2 ng mL -1。该浓度远低于农用化学品防止水生动植物损害登记标准(670 ng mL -1)，因此可以认为氰胺污染对河流中水生动植物的风险可以忽略不计。
{"title":"Developing a Method of Detecting Cyanamide and Monitoring Its Concentrations in Rivers in Osaka","authors":"J. Ono, Koji Ito, Shigeru Suzuki, Y. Yabuki","doi":"10.2965/JSWE.44.9","DOIUrl":"https://doi.org/10.2965/JSWE.44.9","url":null,"abstract":"The concentrations of cyanamide in environmental water have not been reported owing to a lack of its analytical method. We have developed an analytical method for detecting cyanamide in river water and sea water, which includes the derivatization of cyanamide into dansyl-cyanamide, clean-up with a silica gel solid-phase extraction cartridge, and measurement by liquid chromatography/tandem quadrupole mass spectrometry （ LC-MS/MS ） . The method was applied to the determination of cyanamide concentration in river water at nine different locations in Osaka Prefecture. Cyanamide was detected at all locations, and its concentration ranged from a value below the method detection limit （ MDL ） to 4.2 ng mL -1 . The concentrations were much lower than the registration standards of agricultural chemicals concerning prevention of damage to aquatic flora and fauna （ 670 ng mL -1 ） , and thus, the risk of cyanamide pollution to aquatic flora and fauna in the rivers was assumed to be negligible.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80286099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N. Ozaki, K. Wada, M. Murakami, F. Nakajima, H. Furumai
To verify a statistical model for predicting urban pollutant runoff developed in our previous research, newly obtained runoff data were compared with those predicted by the model. The proposed model previously was a regression model using parameters representing geological, rainfall, and hydrological characteristics. The targeted pollutants were COD, SS, TN, and TP, and their event mean concentrations (EMCs) for each rainfall were predicted. From the comparison, the model was found to predict the EMC to one order of magnitude. Moreover, the yearly mean EMC was evaluated from only the mean and standard deviation of all data for each index. The error ratio of the prediction of the mean of 50 rainfall events was within 50%. Furthermore, in order to consider the possible differences among different catchment areas, the EMC values for three catchment areas newly obtained were compared statistically with nationwide values obtained previously. Significant differences were found for one area out of the three which thus emphasizes the importance of the consideration of catchment area differences. Thereafter, the number of runoff samples in a specific watershed area required to detect the mean EMC difference from the nationwide database was derived statistically. This number was calculated to be 10 at most for detecting more than double or less than half of the database means. Lastly, a modified model that includes watershed area differences using a generalized linear mixed model was proposed.
{"title":"Prediction of Urban Non-point Pollution Load by Statistical Analysis of Data of Published Research and Its Reliability Evaluation –Statistical Analysis of Mean Load and Verification and Modification of Previously Proposed Model Using Newly Obtained Data–","authors":"N. Ozaki, K. Wada, M. Murakami, F. Nakajima, H. Furumai","doi":"10.2965/JSWE.44.1","DOIUrl":"https://doi.org/10.2965/JSWE.44.1","url":null,"abstract":"To verify a statistical model for predicting urban pollutant runoff developed in our previous research, newly obtained runoff data were compared with those predicted by the model. The proposed model previously was a regression model using parameters representing geological, rainfall, and hydrological characteristics. The targeted pollutants were COD, SS, TN, and TP, and their event mean concentrations (EMCs) for each rainfall were predicted. From the comparison, the model was found to predict the EMC to one order of magnitude. Moreover, the yearly mean EMC was evaluated from only the mean and standard deviation of all data for each index. The error ratio of the prediction of the mean of 50 rainfall events was within 50%. Furthermore, in order to consider the possible differences among different catchment areas, the EMC values for three catchment areas newly obtained were compared statistically with nationwide values obtained previously. Significant differences were found for one area out of the three which thus emphasizes the importance of the consideration of catchment area differences. Thereafter, the number of runoff samples in a specific watershed area required to detect the mean EMC difference from the nationwide database was derived statistically. This number was calculated to be 10 at most for detecting more than double or less than half of the database means. Lastly, a modified model that includes watershed area differences using a generalized linear mixed model was proposed.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85058620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chizuru Kitayama, Kenji Morita, H. Fukuchi, SungAe Lee, H. Furumai
Fecal pollution caused by combined sewer overflows has been observed at urban waterfronts after rainfall and results in fecal pollution levels exceeding bathing water quality standards. To guarantee the swimmablility of urban waterfronts, it is necessary to predict the situation of fecal contamination to ensure safe bathing. Therefore, we aimed to develop a water-quality forecasting system for the beach in Odaiba Marine Park using Escherichia coli as a fecal indictor to determine whether people can submerge their faces in the seawater on the day of bathing. First, rainfall events in the 23 cities of Tokyo over the past 10 years were categorized by cluster analysis, considering their temporospatial distribution characteristics. Then, E. coli concentration changes in the park were calculated using a 3D hydrodynamic and water-quality model for each categorized rainfall group. Using the calculation results for various tidal conditions, we constructed a database of E. coli concentration changes. It was confirmed that the E. coli concentration predicted using the database for a corresponding rainfall group agrees with the concentration peak calculated using the model within a safe margin. Using the constructed database, we carried out a trial operation of the water-quality forecasting system for the beach in 2018 and verified its effectiveness.
{"title":"Trial Operation of Water-quality Forecasting System Based on Fecal Pollution Indicators for a Beach in Odaiba Marine Park","authors":"Chizuru Kitayama, Kenji Morita, H. Fukuchi, SungAe Lee, H. Furumai","doi":"10.2965/JSWE.44.59","DOIUrl":"https://doi.org/10.2965/JSWE.44.59","url":null,"abstract":"Fecal pollution caused by combined sewer overflows has been observed at urban waterfronts after rainfall and results in fecal pollution levels exceeding bathing water quality standards. To guarantee the swimmablility of urban waterfronts, it is necessary to predict the situation of fecal contamination to ensure safe bathing. Therefore, we aimed to develop a water-quality forecasting system for the beach in Odaiba Marine Park using Escherichia coli as a fecal indictor to determine whether people can submerge their faces in the seawater on the day of bathing. First, rainfall events in the 23 cities of Tokyo over the past 10 years were categorized by cluster analysis, considering their temporospatial distribution characteristics. Then, E. coli concentration changes in the park were calculated using a 3D hydrodynamic and water-quality model for each categorized rainfall group. Using the calculation results for various tidal conditions, we constructed a database of E. coli concentration changes. It was confirmed that the E. coli concentration predicted using the database for a corresponding rainfall group agrees with the concentration peak calculated using the model within a safe margin. Using the constructed database, we carried out a trial operation of the water-quality forecasting system for the beach in 2018 and verified its effectiveness.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84324638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Because of the reduction of nutrients in marine areas nationwide, the rates of achieving total nitrogen （ TN ） and total phosphorus （ TP ） water quality standards have reached 96% and 95%, respectively. Nevertheless, the achievement rate of the chemical oxygen demand （ COD ） standard has remained almost unchanged over the last 30 years. The cause of this discrepancy was investigated in Osaka Bay and the following was found. Eutrophication measures such as “TN reduction to suppress the occurrence of high-concentration phytoplankton blooms （ red tide ） ” are working effectively. This was seen in the water quality indicators associated with particulate organic matter. In contrast, the amount of dissolved organic matter has not decreased. The reduction of nutrients has resulted in a rise in the C: N ratio of organic matter, caused by the constancy of the organic carbon concentration and the decrease in organic nitrogen concentration. A discrepancy between COD and TOC trends has also occurred. It was common to Tokyo Bay and Ise Bay that COD has not decreased because nutrient reduction induces a change in the quality of organic matter.
{"title":"Impact of Nutrient Reduction on Organic Matter (COD and TOC) in Coastal Embayments: Effect of the Reduction and Its Working Mechanism","authors":"T. Fujiwara, Motoharu Suzuki, Kei Okubo","doi":"10.2965/jswe.44.185","DOIUrl":"https://doi.org/10.2965/jswe.44.185","url":null,"abstract":"Because of the reduction of nutrients in marine areas nationwide, the rates of achieving total nitrogen （ TN ） and total phosphorus （ TP ） water quality standards have reached 96% and 95%, respectively. Nevertheless, the achievement rate of the chemical oxygen demand （ COD ） standard has remained almost unchanged over the last 30 years. The cause of this discrepancy was investigated in Osaka Bay and the following was found. Eutrophication measures such as “TN reduction to suppress the occurrence of high-concentration phytoplankton blooms （ red tide ） ” are working effectively. This was seen in the water quality indicators associated with particulate organic matter. In contrast, the amount of dissolved organic matter has not decreased. The reduction of nutrients has resulted in a rise in the C: N ratio of organic matter, caused by the constancy of the organic carbon concentration and the decrease in organic nitrogen concentration. A discrepancy between COD and TOC trends has also occurred. It was common to Tokyo Bay and Ise Bay that COD has not decreased because nutrient reduction induces a change in the quality of organic matter.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75436595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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