A STUDY OF WATER MASS STRUCTURE FROM CONTINUOUS OBSERVATION OF UPWELLING EVENT AT THE INNER PART OF TOKYO BAY

Japan experienced serious water pollution during the period of high economic growth in 1960s. It was also the period that we had such damages to human health, fishery and living conditions due to red tide as much of chemicals, organic materials and the like flowing into the seas along the growing population and industries in the coastal areas. Notable in those days was the issues of environment conservation in the enclosed coastal seas where pollutants were prone to accumulate inside due to low level of water circulation, resulting in the issues including red tide and oxygen-deficient water mass. In responding to these issues, we implemented countermeasures like effluent control with the Water Pollution Control Law and improvement/expansion of sewage facilities. In the extensive enclosed coastal seas of Tokyo Bay, Ise Bay and the Seto Inland Sea, the three areas of high concentration of population, we implemented water quality total reduction in seven terms from 1979, reducing the total quantities of pollutant load of COD, TN and TP. Sea water quality hence has been on an improvement trend as a whole along the steady reduction of pollutants from the land. We however recognize that there are differences in improvement by sea area such as red tide and oxygen-deficient water mass continue to occur in some areas. Meanwhile, it has been pointed out that bio-diversity and bio-productivity should be secured through conservation/creation of tidal flats and seaweed beds in the view point of “Bountiful Sea” To work at these challenges, through the studies depending on the circumstances of the water environment in the enclosed coastal seas, we composed “The Policy of Desirable State of 8th TPLCS” in 2015. We have also added the sediment DO into the water quality standard related to the life-environmental items in view of the preservation of aquatic creatures in the enclosed water areas. Important from now on, along the Policy, is to proceed with necessary measures to improve water quality with good considerations of differences by area in the view point of “Beautiful and bountiful Sea”.

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Seasonal Ekman upwelling in the Southwest Sumba from INDESO Model

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/944/1/012063 ◽

2021 ◽

Vol 944 (1) ◽

pp. 012063

Author(s):

M W Suryadarma ◽

A S Atmadipoera ◽

N M N Natih ◽

A Koch-Larrouy

Keyword(s):

Water Mass ◽

Indonesian Throughflow ◽

Sea Level Anomaly ◽

Monsoon Period ◽

Salinity Stratification ◽

Fisheries Resources ◽

Upwelling Index ◽

Ekman Upwelling ◽

Upwelling Event ◽

Upwelling Area

Abstract Southwest Sumba water is part of the Indonesian fisheries management region (WPP573). Marine fisheries resources are influenced by oceanographic phenomena such as an upwelling event. This study aims to describe characteristics of seasonal Ekman upwelling by analyzing oceanographic parameters from the validated INDESO model output (2008-2014). It shows that upwelling event in the study area occurs during the Southeast Monsoon period, which creates an Ekman drift of 0.26 Sv towards offshore. This transported water mass is then replaced by an upwelled vertical flow of sub-surface colder and nutrient-rich water at the velocity of the order of 10−4 m/s. Surface features of the upwelling event are seen from a minimum temperature (24.3 °C), sea level anomaly (0.34 m), but the maximum of chlorophyll-a (3.02 mg/m3). During this time, an uplifted isotherm of 25.5 °C is found from sub-surface to 10 m depth, but it is outcropped at the sea surface in the centre of upwelling area. Interestingly, during upwelling event, salinity stratification revealed an isohaline of 34.10 psu is much deeper at 40 m depth, and much fresher water mass from the Ombai Indonesian Throughflow water is dominant. Averaged temperature-based upwelling index between June-September is about 0.3 °C.

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MEASURES FOR ENVIRONMENT CONSERVATION IN ENCLOSED COASTAL SEAS

Proceedings of International Conference "Managinag risks to coastal regions and communities in a changinag world" (EMECS'11 - SeaCoasts XXVI) ◽

10.31519/conferencearticle_5b1b940c149362.66419597 ◽

2017 ◽

Author(s):

Keizo Negi ◽

Takuya Ishikawa ◽

Kenichiro Iba ◽

...

Keyword(s):

Water Pollution ◽

Water Quality ◽

Water Mass ◽

Sea Water ◽

Red Tide ◽

Water Environment ◽

Quality Standard ◽

Tokyo Bay ◽

View Point ◽

High Concentration

Japan experienced serious water pollution during the period of high economic growth in 1960s. It was also the period that we had such damages to human health, fishery and living conditions due to red tide as much of chemicals, organic materials and the like flowing into the seas along the growing population and industries in the coastal areas. Notable in those days was the issues of environment conservation in the enclosed coastal seas where pollutants were prone to accumulate inside due to low level of water circulation, resulting in the issues including red tide and oxygen-deficient water mass. In responding to these issues, we implemented countermeasures like effluent control with the Water Pollution Control Law and improvement/expansion of sewage facilities. In the extensive enclosed coastal seas of Tokyo Bay, Ise Bay and the Seto Inland Sea, the three areas of high concentration of population, we implemented water quality total reduction in seven terms from 1979, reducing the total quantities of pollutant load of COD, TN and TP. Sea water quality hence has been on an improvement trend as a whole along the steady reduction of pollutants from the land. We however recognize that there are differences in improvement by sea area such as red tide and oxygen-deficient water mass continue to occur in some areas. Meanwhile, it has been pointed out that bio-diversity and bio-productivity should be secured through conservation/creation of tidal flats and seaweed beds in the view point of “Bountiful Sea” To work at these challenges, through the studies depending on the circumstances of the water environment in the enclosed coastal seas, we composed “The Policy of Desirable State of 8th TPLCS” in 2015. We have also added the sediment DO into the water quality standard related to the life-environmental items in view of the preservation of aquatic creatures in the enclosed water areas. Important from now on, along the Policy, is to proceed with necessary measures to improve water quality with good considerations of differences by area in the view point of “Beautiful and bountiful Sea”.

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Relationship of Water Quality and Flow between the Mouth and the Head of Tokyo Bay based on the Long Term Continuous Observation

PROCEEDINGS OF COASTAL ENGINEERING JSCE ◽

10.2208/proce1989.55.1076 ◽

2008 ◽

Vol 55 ◽

pp. 1076-1080

Author(s):

Kojiro SUZUKI ◽

Masahiko ISOBE ◽

Kazunobu MOROHOSHI

Keyword(s):

Water Quality ◽

Tokyo Bay ◽

Continuous Observation ◽

Relationship Of

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Temporal and spatial variations of hypoxic water mass in Tokyo bay governed by the coastal upwelling at bay mouth and wind-driven current

PROCEEDINGS OF COASTAL ENGINEERING JSCE ◽

10.2208/proce1989.55.1081 ◽

2008 ◽

Vol 55 ◽

pp. 1081-1085 ◽

Cited By ~ 3

Author(s):

Hiroshi YAGI ◽

Tanuspong POKAVANICH ◽

Susumu YASUI ◽

Kazuo NADAOKA ◽

Ryuichi ARIJI ◽

...

Keyword(s):

Water Mass ◽

Coastal Upwelling ◽

Spatial Variations ◽

Tokyo Bay ◽

Temporal And Spatial Variations ◽

Hypoxic Water ◽

Temporal And Spatial

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SPATIAL DISTRIBUTION OF HYPOXIC WATER MASS BASED ON A MONITORING CAMPAIGN OF BAY ENVIRONMENT AT TOKYO BAY, JAPAN.

Coastal Engineering Proceedings ◽

10.9753/icce.v32.management.51 ◽

2011 ◽

Vol 1 (32) ◽

pp. 51

Author(s):

Takehito Horie ◽

Keita Furukawa ◽

Tomonari Okada

Keyword(s):

Spatial Distribution ◽

Dissolved Oxygen ◽

Tidal Flat ◽

Water Mass ◽

River Estuary ◽

Tokyo Bay ◽

Monitoring Campaign ◽

Hypoxic Water ◽

Vertical Spacing ◽

Sea Area

In 2008, a monitoring campaign of bay environment had been done at Tokyo Bay, Japan. This campaign has been a part of implementation of the bay renaissance plan enacted since 2005. The data was collected by 46 institutions in 568 monitoring points in around 2nd July 2008. Dissolved oxygen, salinity and temperature were monitored in sea area basically from the surface to the bottom with 1.0 m vertical spacing at the monitoring points. We analyzed spatial distribution of hypoxic water mass based on this monitoring campaign data. Following results are obtained that 1) Measurement results showed that the bottom hypoxic water mass dominated in the head of Tokyo bay, while dissolved oxygen concentration was high condition in tidal flat and in shallow water, such as the Tama River estuary, Sanbanze tidal flat area and the Ara River estuary. 2) We proposed new parameters, such as CDZ and VDZ, which showed characteristic of spatial distribution of hypoxic water. The proposed parameters could be related to the temporal and spatial development of hypoxic water. Thus, these parameters will extend the interpretation of conservative bottom dissolved oxygen (DOB) data to understand the dynamics of hypoxic water.

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