The research centered on the groundwater quality parameters in five boreholes and three wells in residential urban areas of Zimbabwe. Ten runs of chemical analysis for water pH, EC （electrical conductivity）, water h...The research centered on the groundwater quality parameters in five boreholes and three wells in residential urban areas of Zimbabwe. Ten runs of chemical analysis for water pH, EC （electrical conductivity）, water hardness were carried out weekly and averages were calculated for each at Bindura University laboratory. Iron concentrations analysis was done at the Tobacco Research Station. The results from boreholes and wells were compared to the WHO （World Health Organisation） drinking water acceptable standards to measure the deviations. It was found that the boreholes had hard waters （112 mg/L）, EC （425 s/m） and iron concentration （0.49 ppm） outside the WHO standards （〉 64 mg/L; 400 s/m; 0.3 ppm respectively）. In contrary the wells had only the water pH slightly outside the acceptable ranges （5.8）; other parameters were in the acceptable ranges （EC 379 s/m; water hardness 0.38 mg/L as CaCO3 and iron concentration 0.38 ppm）. The difference in chemical composition between the boreholes and wells caused the borehole water rejection in favor of well water. High iron concentrations and water hardness in boreholes were major contributors to the water rejection by the residents.展开更多
After the Tianjin Port 8.12 explosion, an enormous amount of potassium dichromate （K2Cr2O7） and butanone （CH3COCH2CH3） leaked into the coastal soil-groundwater system, which potentially threatened the environment ...After the Tianjin Port 8.12 explosion, an enormous amount of potassium dichromate （K2Cr2O7） and butanone （CH3COCH2CH3） leaked into the coastal soil-groundwater system, which potentially threatened the environment and human health. Determining the transport process of hazards is necessary to establish guidelines for remediating the contaminated area. This work aims to investigate the migration of potassium dichromate and butanone in the coastal soil-groundwater system through a coupling unsaturated-saturated numerical model, incorporating the HYDRUS model into the MODFLOW/ MT3D model. In the unsaturated zone, two-dimensional HYDRUS model was applied, and its recharge flux at the bottom boundary was utilized as the input of MODFLOW/MT3D model in the saturated zone. Results showed that Cr2O^（2-）7 migrated much faster than butanone in the unsaturated zone and reached the water table in about 1 year. In comparison, butanone was unlikely to enter the aquifer even 5 years later with a migration depth of about 2.2 m. Driven by groundwater, the Cr2O^（2-）7 that entered the aquifer migrated about 161 m toward southeast 5 years later. In the saturated zone, the contamination plume covered mainly the southeast area due to the groundwater flow direction.展开更多
An effective evaluation system can provide specific and practical suggestions to the deep groundwater management. But such kind of evaluation system has not been proposed in China. In this study, an evaluation index s...An effective evaluation system can provide specific and practical suggestions to the deep groundwater management. But such kind of evaluation system has not been proposed in China. In this study, an evaluation index system is specifically developed to evaluate deep groundwater management efficiency. It is composed of three first-level indicators(law enforcement capability, management ability, and management effectiveness) and eleven second-level indicators. The second-level indicators include seven mandatory indicators and four optional indicators. Piecewise linear function is used to normalize the quantitative indicators, and expert scoring method and questionnaire survey method are used to normalize the qualitative indicators. Then a comprehensive indicator weighting evaluation method is used to evaluate the first-level indicators and the target topic. A case study is carried out to evaluate deep groundwater management efficiency in Tianjin City. According to the evaluation score in each period, the management efficiency of every district in Tianjin City gradually improved. The overall evaluation score in the early deep groundwater extraction period is 0.12. After a series of deep groundwater protection efforts, this score reached to 0.61 in 2007, and met the regulation criteria. The evaluation results also showed that the further groundwater management efforts in Tianjin City should be focused on building a dynamic database to collect comprehensive deep well-log data; and on a reasonable design and distribution of the groundwater monitoring network. It demonstrated that the index system is suitable to locate the deficiencies of current groundwater management systems and to guide further improvements. It can then be used to protect deep groundwater.展开更多
Shear wave velocity is one of the important dynamic characteristics of soil layers and applied widely in aseismic engineering. In this paper, 500 drill logging data are used to make a linear interpolation based on 0. ...Shear wave velocity is one of the important dynamic characteristics of soil layers and applied widely in aseismic engineering. In this paper, 500 drill logging data are used to make a linear interpolation based on 0. 01° x 0. 01°x lm grid. A shallow 3-D shear wave velocity structure of Tianjin coastal area is obtained. According to the data and geological background, we selected two typical velocity profiles to try to introduce and explain its relationship to basement structure. The results show that the shear wave velocity structure clearly presents the characteristic of stratification and lateral inhomogeneity. Furthermore, the difference of the shear wave structure between tectonic elements is clear and the velocity structure between the two sides of the local or border fault in the Quaternary is disturbed or affected significantly. It intuitively shows that the basement structure and fault activity of this region had good control of sedimentation development and strata formation in the Quaternary period which would have an important effect on engineering seismic and geological condition evaluation.展开更多
文摘The research centered on the groundwater quality parameters in five boreholes and three wells in residential urban areas of Zimbabwe. Ten runs of chemical analysis for water pH, EC （electrical conductivity）, water hardness were carried out weekly and averages were calculated for each at Bindura University laboratory. Iron concentrations analysis was done at the Tobacco Research Station. The results from boreholes and wells were compared to the WHO （World Health Organisation） drinking water acceptable standards to measure the deviations. It was found that the boreholes had hard waters （112 mg/L）, EC （425 s/m） and iron concentration （0.49 ppm） outside the WHO standards （〉 64 mg/L; 400 s/m; 0.3 ppm respectively）. In contrary the wells had only the water pH slightly outside the acceptable ranges （5.8）; other parameters were in the acceptable ranges （EC 379 s/m; water hardness 0.38 mg/L as CaCO3 and iron concentration 0.38 ppm）. The difference in chemical composition between the boreholes and wells caused the borehole water rejection in favor of well water. High iron concentrations and water hardness in boreholes were major contributors to the water rejection by the residents.
基金supported by the National Natural Science Foundation of China(No.21656001)
文摘After the Tianjin Port 8.12 explosion, an enormous amount of potassium dichromate （K2Cr2O7） and butanone （CH3COCH2CH3） leaked into the coastal soil-groundwater system, which potentially threatened the environment and human health. Determining the transport process of hazards is necessary to establish guidelines for remediating the contaminated area. This work aims to investigate the migration of potassium dichromate and butanone in the coastal soil-groundwater system through a coupling unsaturated-saturated numerical model, incorporating the HYDRUS model into the MODFLOW/ MT3D model. In the unsaturated zone, two-dimensional HYDRUS model was applied, and its recharge flux at the bottom boundary was utilized as the input of MODFLOW/MT3D model in the saturated zone. Results showed that Cr2O^（2-）7 migrated much faster than butanone in the unsaturated zone and reached the water table in about 1 year. In comparison, butanone was unlikely to enter the aquifer even 5 years later with a migration depth of about 2.2 m. Driven by groundwater, the Cr2O^（2-）7 that entered the aquifer migrated about 161 m toward southeast 5 years later. In the saturated zone, the contamination plume covered mainly the southeast area due to the groundwater flow direction.
基金Under the auspices of National Basic Research Program of China(No.2010CB428804)
文摘An effective evaluation system can provide specific and practical suggestions to the deep groundwater management. But such kind of evaluation system has not been proposed in China. In this study, an evaluation index system is specifically developed to evaluate deep groundwater management efficiency. It is composed of three first-level indicators(law enforcement capability, management ability, and management effectiveness) and eleven second-level indicators. The second-level indicators include seven mandatory indicators and four optional indicators. Piecewise linear function is used to normalize the quantitative indicators, and expert scoring method and questionnaire survey method are used to normalize the qualitative indicators. Then a comprehensive indicator weighting evaluation method is used to evaluate the first-level indicators and the target topic. A case study is carried out to evaluate deep groundwater management efficiency in Tianjin City. According to the evaluation score in each period, the management efficiency of every district in Tianjin City gradually improved. The overall evaluation score in the early deep groundwater extraction period is 0.12. After a series of deep groundwater protection efforts, this score reached to 0.61 in 2007, and met the regulation criteria. The evaluation results also showed that the further groundwater management efforts in Tianjin City should be focused on building a dynamic database to collect comprehensive deep well-log data; and on a reasonable design and distribution of the groundwater monitoring network. It demonstrated that the index system is suitable to locate the deficiencies of current groundwater management systems and to guide further improvements. It can then be used to protect deep groundwater.
基金jointly sponsored by the Special Program of Science and Technology Innovation of Tianjin Municipality ( 07FDZDSF02102 )the Geological Program of Mineral Resources Compensation of Tianjin Municipality,China
文摘Shear wave velocity is one of the important dynamic characteristics of soil layers and applied widely in aseismic engineering. In this paper, 500 drill logging data are used to make a linear interpolation based on 0. 01° x 0. 01°x lm grid. A shallow 3-D shear wave velocity structure of Tianjin coastal area is obtained. According to the data and geological background, we selected two typical velocity profiles to try to introduce and explain its relationship to basement structure. The results show that the shear wave velocity structure clearly presents the characteristic of stratification and lateral inhomogeneity. Furthermore, the difference of the shear wave structure between tectonic elements is clear and the velocity structure between the two sides of the local or border fault in the Quaternary is disturbed or affected significantly. It intuitively shows that the basement structure and fault activity of this region had good control of sedimentation development and strata formation in the Quaternary period which would have an important effect on engineering seismic and geological condition evaluation.
