Analysis and numerical simulation of natural and human-caused low dissolved oxygen in the Minjiang River Estuary

2016 ◽  
Vol 73 (10) ◽  
pp. 2475-2485 ◽  
Author(s):  
Peng Zhang ◽  
Yong Pang ◽  
Chengchun Shi ◽  
Yishu Wang ◽  
Lei Xu ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Dissolved Oxygen ◽  
Water Temperature ◽  
River Discharge ◽  
Flood Control ◽  
Nutrient Loading ◽  
River Estuary ◽  
Water Age ◽  
Drought Period ◽  
Minjiang River

The Minjiang River, a typical tidal channel in Southeast China, plays an important role in the supply of drinking water, flood control and drought relief, farming and navigation, as well as shipping and other functions. Dissolved oxygen (DO), as a basic living condition for aquatic biota, has been deteriorating in the Minjiang River in recent years. In order to understand how the spatial distribution of DO responds to river discharge, nutrient loading and water temperature, a three-dimensional Environmental Fluid Dynamics Code model was used to simulate water age and the distribution of DO in the Minjiang River. The model presented in this paper was used for water resource and water quality simulations under various physical, chemical, and biological scenarios. Sensitivity simulation results indicated that the three factors had a significant impact on the spatial distribution variation of DO in the Minjiang River. Increased river discharge or split ratio of the North Channel resulted in decreased water age and increased DO. Increased nutrient loading and water temperature caused lower DO. In order to protect coastal environments in the Minjiang River, river discharge should be increased and pollutants of local cities should be reduced during the high temperature and drought period.

Hypoxia-based habitat compression in the Neuse River Estuary: context-dependent shifts in behavioral avoidance thresholds

2002 ◽  
Vol 59 (6) ◽  
pp. 952-965 ◽  
Author(s):  
Lisa A Eby ◽  
Larry B Crowder
Keyword(s):  
Dissolved Oxygen ◽  
Nutrient Loading ◽  
Sublethal Effects ◽  
River Estuary ◽  
Classification And Regression Tree ◽  
Neuse River Estuary ◽  
Estuarine Fish ◽  
Behavioral Avoidance ◽  
Context Dependent ◽  
Oxygen Concentrations

Anthropogenic activities in estuarine watersheds alter physical and chemical characteristics of these ecosystems. Increased nutrient loading and changes in hydrology affect oxygen budgets and subsequently alter the spatial and temporal extent of hypoxia. We used classification and regression tree analyses to examine behavioral avoidance thresholds over a range of dissolved oxygen concentrations. In an examination of 10 fish species, all avoided areas with dissolved oxygen concentrations of <2.0 mg·L–1. Our data suggest that the dissolved oxygen avoidance threshold expressed by fish may be context-dependent. Specifically, the spatial extent of hypoxia significantly affected avoidance thresholds. Fish may occupy poorer quality habitat (areas with lower dissolved oxygen levels) as conditions worsen and the size of the oxygenated refuge shrinks. When the entire estuary is oxygenated, fish utilize all depths. During hypoxic episodes, fish are restricted to oxygenated, shallow, warmer areas. This habitat compression may result in higher densities and greater overlap with potential competitors and predators. Hypoxic zones alter habitat use and may increase bioenergetic costs, potentially resulting in sublethal effects, i.e., decreased growth and condition, on the estuarine fish community.

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

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.

A study on bioecology of macroalgae, genus Caulerpa in northern Minahasa Waters, North Sulawesi Province

2013 ◽  
Vol 1 (1) ◽  
pp. 26
Author(s):  
Irma Pulukadan ◽  
Rene Ch Keppel ◽  
Grevo S Gerung
Keyword(s):  
Dissolved Oxygen ◽  
Water Temperature ◽  
Raw Materials ◽  
Economic Value ◽  
Algal Growth ◽  
Environmental Parameters ◽  
Caulerpa Racemosa ◽  
Bottom Substrate ◽  
North Sulawesi ◽  
Ecological Aspects

Alga is a marine resource of potential to fisheries and marine sector. It has an important economic value to promote the economy in Indonesia. Nowdays, algae have been used as a relatively high value fisheries commodity since it has been used for food, industrial, pharmaceutical and cosmetic raw materials. This important potential needs to be supported with understanding of its biology and ecology, so that its utilization could increase the livelihood of the coastal villagers. This study was aimed at inventorying and identifying the members of genus Caulerpa found in North Minahasa Regency waters and studying some biological and ecological aspects of the algae in the area. Resuls showed that there were 7 species recorded, Caulerpa racemosa, C. racemosa var. macrophysa, C. sertularioides, C. taxifolia, C. serrulata,C. lentillifera and C. peltata. Ecologically, the environmental parameters, such as water temperature, salinity, pH, dissolved oxygen, turbidity, were in tolerable ranges for algal growth. Bottom substrate supported the growth of genus Caulerpa as well© Saat ini alga dijadikan sebagai komoditas hasil perikanan dengan nilai ekonomis yang relatif tinggi karena manfaatnya sebagai bahan makanan serta bahan baku industri, farmasi, dan kosmetik. Potensi yang cukup penting ini harus ditunjang dengan ilmu pengetahuan tentang biologi dan ekologi dari alga laut, sehingga pemanfaatannya dapat meningkatkan taraf hidup masyarakat pesisir. Penelitian tentang kajian bioekologi alga makro genus Caulerpa di perairan Minahasa Utara ini dilaksanakan dan diharapkan dapat memberikan informasi ilmiah tentang bioekologi alga makro genus Caulerpa, sehingga dapat dimanfaatkan untuk pengembangan pemanfaatan bagi kepentingan masyarakat pesisir khususnya dan industri alga makro umumnya. Penelitian ini bertujuan untuk menginventarisasi dan mengidentifikasi alga makro genus Caulerpa di perairan Kabupaten Minahasa Utara, dan mengkaji aspek bioekologinya. Hasil penelitian menunjukkan bahwa ditemukan 7 spesies, yaitu Caulerpa racemosa, C. racemosa var. macrophysa, C. sertularioides, C. taxifolia, C. serrulata, C. lentillifera dan C. peltata. Parameter lingkungan seperti suhu, salinitas, pH, oksigen terlarut, tingkat kecerahan air berada pada kisaran yang dapat ditolerir untuk pertumbuhan alga makro, sedangkan substrat juga mendukung pertumbuhan alga makro ini©

scholarly journals Spatial and Temporal Variability of Soil Salinity in the Yangtze River Estuary Using Electromagnetic Induction

2021 ◽  
Vol 13 (10) ◽  
pp. 1875
Author(s):  
Wenping Xie ◽  
Jingsong Yang ◽  
Rongjiang Yao ◽  
Xiangping Wang
Keyword(s):  
Electrical Conductivity ◽  
Spatial Distribution ◽  
Soil Salinity ◽  
Yangtze River ◽  
Laboratory Data ◽  
River Estuary ◽  
Yangtze River Estuary ◽  
Soil Electrical Conductivity ◽  
The Yangtze River ◽  
The Yangtze River Estuary

Soil salt-water dynamics in the Yangtze River Estuary (YRE) is complex and soil salinity is an obstacle to regional agricultural production and the ecological environment in the YRE. Runoff into the sea is reduced during the impoundment period as the result of the water-storing process of the Three Gorges Reservoir (TGR) in the upper reaches of the Yangtze River, which causes serious seawater intrusion. Soil salinity is a problem due to shallow and saline groundwater under serious seawater intrusion in the YRE. In this research, we focused on the temporal variation and spatial distribution characteristics of soil salinity in the YRE using geostatistics combined with proximally sensed information obtained by an electromagnetic induction (EM) survey method in typical years under the impoundment of the TGR. The EM survey with proximal sensing method was applied to perform soil salinity survey in field in the Yangtze River Estuary, allowing quick determination and quantitative assessment of spatial and temporal variation of soil salinity from 2006 to 2017. We developed regional soil salinity survey and mapping by coupling limited laboratory data with proximal sensed data obtained from EM. We interpreted the soil electrical conductivity by constructing a linear model between the apparent electrical conductivity data measured by an EM 38 device and the soil electrical conductivity (EC) of soil samples measured in laboratory. Then, soil electrical conductivity was converted to soil salt content (soil salinity g kg−1) through established linear regression model based on the laboratory data of soil salinity and soil EC. Semivariograms of regional soil salinity in the survey years were fitted and ordinary kriging interpolation was applied in interpolation and mapping of regional soil salinity. The cross-validation results showed that the prediction results were acceptable. The soil salinity distribution under different survey years was presented and the area of salt affected soil was calculated using geostatistics method. The results of spatial distribution of soil salinity showed that soil salinity near the riverbanks and coastlines was higher than that of inland. The spatial distribution of groundwater depth and salinity revealed that shallow groundwater and high groundwater salinity influenced the spatial distribution characteristics of soil salinity. Under long-term impoundment of the Three Gorges Reservoir, the variation of soil salinity in different hydrological years was analyzed. Results showed that the area affected by soil salinity gradually increased in different hydrological year types under the impoundment of the TGR.

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