Based on a coupled hydrodynamic–ecological model for regional and shelf seas (COHERENS), a three-dimensional baroclinic model for the Changjiang (Yangtze) River estuary and the adjacent sea area was established using...Based on a coupled hydrodynamic–ecological model for regional and shelf seas (COHERENS), a three-dimensional baroclinic model for the Changjiang (Yangtze) River estuary and the adjacent sea area was established using the sigma-coordinate in the vertical direction and spherical coordinate in the horizontal direction. In the study, changing-grid technology and the "dry-wet" method were designed to deal with the moving boundary. The minimum water depth limit condition was introduced for numerical simulation stability and to avoid producing negative depths in the shallow water areas. Using the Eulerian transport approaches included in COHERENS for the advection and dispersion of dissolved pollutants, numerical simulation of dissolved pollutant transport and diffusion in the Changjiang River estuary were carried out. The mass centre track of dissolved pollutants released from outlets in the south branch of the Changjiang River estuary water course has the characteristic of reverse current motion in the inner water course and clockwise motion offshore. In the transition area, water transport is a combination of the two types of motion. In a sewage-discharge numerical experiment, it is found that there are mainly two kinds of pollution distribution forms: one is a single nuclear structure and the other is a double nuclear (dinuclear) structure in the turbid zone of the Changjiang River estuary. The rate of expansion of the dissolved pollutant distribution decreased gradually. The results of the numerical experiment indicate that the maximum turbid zone of the Changjiang River estuary is also the zone enriched with pollutants. Backward pollutant flow occurs in the north branch of the estuary, which is similar to the backward salt water flow, and the backward flow of pollutants released upstream is more obvious.展开更多
The Zarafshan river is a main trans-boundary river of the Aral Seabasin. As the main water resource, the Zarafshan river water is mainly used by the republics ofTajikistanandUzbekistan. We explored the trends of space...The Zarafshan river is a main trans-boundary river of the Aral Seabasin. As the main water resource, the Zarafshan river water is mainly used by the republics ofTajikistanandUzbekistan. We explored the trends of space-time pollution of river water with ammonium, nitrates, phosphates, biological oxygen demand (ВОD), fluorine and some heavy metals at seven water sampling points along theZarafshanRiver inUzbekistan. The experimental data showed that the water quality of the Zarafshanriver in 2002-2009 has undergone a considerable transformation, even by the length of the river. The chemical composition of the Zarafshan river water underwent changes due to the agricultural collector-drainage discharges and the sewage of the cities of Samarkand and Navoi. The water pollutants of the Zarafshan river, as a con- sequence of the agricultural pollution, consisted of mineralization, ammonium, nitrate, phosphate, and pesticides. Therefore, it is necessary to monitor the chemical composition of the large agricultural collector-drainage discharges into the river. The main sources of the heavy metals (primarily arsenic and zinc) in the Zarafshan river water were probably ore processing manufactures located interritoryofTajikistan.展开更多
Water samples were collected from three stations along the water course of Oinyi River, Kogi State, Nigeria, bi-monthly for 12 months (October 2010 to September 2011). A total of 16 physical and chemical parameters (t...Water samples were collected from three stations along the water course of Oinyi River, Kogi State, Nigeria, bi-monthly for 12 months (October 2010 to September 2011). A total of 16 physical and chemical parameters (temperature, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, electrical conductivity, flow velocity, depth, nitrate, nitrite, phosphate, ammonia, pH, turbidity, total suspended solids, total dissolved solids and colour) were analyzed and results showed that pH (6.8 to 7.26), conductivity (106.0 to 211.7 μS/cm), colour (3.87 ± 0.159 Pt.Co), turbidity (14 - 22.7 NTU), total suspended solids (45 - 54 mg/l), biochemical oxygen demand (2.05 - 2.89 mg/l), chemical oxygen demand (17.19 ± 0.15 mg/l), temperature (24°C to 27°C) and depth (0.23 to 0.35 m) were significantly different across the different stations and between the months. However, total dissolved solids (52.7 to 108.8 mg/l), dissolved oxygen (6.02 to 7.01 mg/l), ammonia (0.00 to 0.02 mg·l-1), nitrite (0.01 - 0.09 mg·l-1), nitrate (0.045 ± 0.006 mg·l-1), phosphate (0.2 to 2.05 mg·l-1) and flow velocity (0.1 to 0.35 m·s-1) showed variations within the sampling stations. Maximum conductivity (211.7 μS/cm), colour (5.83 Pt.Co), turbidity (22.7 NTU), total suspended solids (54 mg/l), total dissolved solids (108.8 mg/l), nitrite (0.09 mg/l) and nitrate (0.006 mg/l) values were recorded at station 2 which is the discharge point of industrial waste. River water did show significant pollutional increase at the effluent impacted site during the present study. Dissolved oxygen showed direct relation with temperature, biochemical oxygen demand and chemical oxygen demand. The non-stop and continuous discharges of cement waste water into the river lessened water quality with significant or corresponding effect on the biota of the studied area, thus paving way for clear assertion that the water quality deterioration was as a result of the impacts of the waste water from cement industry.展开更多
基金Supported by the Public Welfare Special Scientific Research Project funded by the Ministry of Water Resources of China (No. 200701026)National Natural Science Foundation of China (No. 50709007)the Startup Fund of Hohai University (No. 2084/40801107)
文摘Based on a coupled hydrodynamic–ecological model for regional and shelf seas (COHERENS), a three-dimensional baroclinic model for the Changjiang (Yangtze) River estuary and the adjacent sea area was established using the sigma-coordinate in the vertical direction and spherical coordinate in the horizontal direction. In the study, changing-grid technology and the "dry-wet" method were designed to deal with the moving boundary. The minimum water depth limit condition was introduced for numerical simulation stability and to avoid producing negative depths in the shallow water areas. Using the Eulerian transport approaches included in COHERENS for the advection and dispersion of dissolved pollutants, numerical simulation of dissolved pollutant transport and diffusion in the Changjiang River estuary were carried out. The mass centre track of dissolved pollutants released from outlets in the south branch of the Changjiang River estuary water course has the characteristic of reverse current motion in the inner water course and clockwise motion offshore. In the transition area, water transport is a combination of the two types of motion. In a sewage-discharge numerical experiment, it is found that there are mainly two kinds of pollution distribution forms: one is a single nuclear structure and the other is a double nuclear (dinuclear) structure in the turbid zone of the Changjiang River estuary. The rate of expansion of the dissolved pollutant distribution decreased gradually. The results of the numerical experiment indicate that the maximum turbid zone of the Changjiang River estuary is also the zone enriched with pollutants. Backward pollutant flow occurs in the north branch of the estuary, which is similar to the backward salt water flow, and the backward flow of pollutants released upstream is more obvious.
文摘The Zarafshan river is a main trans-boundary river of the Aral Seabasin. As the main water resource, the Zarafshan river water is mainly used by the republics ofTajikistanandUzbekistan. We explored the trends of space-time pollution of river water with ammonium, nitrates, phosphates, biological oxygen demand (ВОD), fluorine and some heavy metals at seven water sampling points along theZarafshanRiver inUzbekistan. The experimental data showed that the water quality of the Zarafshanriver in 2002-2009 has undergone a considerable transformation, even by the length of the river. The chemical composition of the Zarafshan river water underwent changes due to the agricultural collector-drainage discharges and the sewage of the cities of Samarkand and Navoi. The water pollutants of the Zarafshan river, as a con- sequence of the agricultural pollution, consisted of mineralization, ammonium, nitrate, phosphate, and pesticides. Therefore, it is necessary to monitor the chemical composition of the large agricultural collector-drainage discharges into the river. The main sources of the heavy metals (primarily arsenic and zinc) in the Zarafshan river water were probably ore processing manufactures located interritoryofTajikistan.
文摘Water samples were collected from three stations along the water course of Oinyi River, Kogi State, Nigeria, bi-monthly for 12 months (October 2010 to September 2011). A total of 16 physical and chemical parameters (temperature, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, electrical conductivity, flow velocity, depth, nitrate, nitrite, phosphate, ammonia, pH, turbidity, total suspended solids, total dissolved solids and colour) were analyzed and results showed that pH (6.8 to 7.26), conductivity (106.0 to 211.7 μS/cm), colour (3.87 ± 0.159 Pt.Co), turbidity (14 - 22.7 NTU), total suspended solids (45 - 54 mg/l), biochemical oxygen demand (2.05 - 2.89 mg/l), chemical oxygen demand (17.19 ± 0.15 mg/l), temperature (24°C to 27°C) and depth (0.23 to 0.35 m) were significantly different across the different stations and between the months. However, total dissolved solids (52.7 to 108.8 mg/l), dissolved oxygen (6.02 to 7.01 mg/l), ammonia (0.00 to 0.02 mg·l-1), nitrite (0.01 - 0.09 mg·l-1), nitrate (0.045 ± 0.006 mg·l-1), phosphate (0.2 to 2.05 mg·l-1) and flow velocity (0.1 to 0.35 m·s-1) showed variations within the sampling stations. Maximum conductivity (211.7 μS/cm), colour (5.83 Pt.Co), turbidity (22.7 NTU), total suspended solids (54 mg/l), total dissolved solids (108.8 mg/l), nitrite (0.09 mg/l) and nitrate (0.006 mg/l) values were recorded at station 2 which is the discharge point of industrial waste. River water did show significant pollutional increase at the effluent impacted site during the present study. Dissolved oxygen showed direct relation with temperature, biochemical oxygen demand and chemical oxygen demand. The non-stop and continuous discharges of cement waste water into the river lessened water quality with significant or corresponding effect on the biota of the studied area, thus paving way for clear assertion that the water quality deterioration was as a result of the impacts of the waste water from cement industry.
