Lake eutrophication （LE） has become an increasingly severe environmental problem recently. However, there has been no nutrient standard established for LE control in many developing countries such as China. This stu...Lake eutrophication （LE） has become an increasingly severe environmental problem recently. However, there has been no nutrient standard established for LE control in many developing countries such as China. This study proposes a structural equation model to assist in the establishment of a lake nutrient standard for drinking water sources in Yunnan-Guizhou Plateau Ecoregion （Yungui Ecoregion）, China. The modeling results indicate that the most predictive indicator for designated use-attainment is total phosphorus （TP） （total effect =-0.43）, and chlorophyll a （Chl-a） is recommended as the second important indicator （total effect =-0.41）. The model is further used for estimating the probability of use-attainment associated with lake water as a drinking water source and various levels of candidate criteria （based on the reference conditions and the current environmental quality standards for surface water）. It is found that these candidate criteria cannot satisfy the designated 100% use-attainment. To achieve the short-term target （85% attainment of the designated use）, TP and Chl-a values ought to be less than 0.02 mg/L and 1.4 μg/L, respectively. When used as a long-term target （90% or greater attainment of the designated use）, the TP and Chl-a values are suggested to be less than 0.018 mg/L and 1 μg/L, respectively.展开更多
A groundwater flow and solute transport model was developed using Visual Modflow for forecasting contaminant transport and assessing effects of remedial alternatives based on a case study of an unregulated landfill le...A groundwater flow and solute transport model was developed using Visual Modflow for forecasting contaminant transport and assessing effects of remedial alternatives based on a case study of an unregulated landfill leachate-contaminated groundwater in eastern China. The results showed that arsenic plume was to reach the pumping well in the downstream farmland after eight years, and the longest lateral and longitudinal distance of arsenic plume was to reach 200 m and 260 m, respectively. But the area of high concentration region of arsenic plume was not to obviously increase from eight years to ten years and the plume was to spread to the downstream river and the farmland region after 20 years; while the landfill＇s ground was hardened, the plume was not to reach the downstream farmland region after eight years; when the pumping well was installed in the plume downstream and discharge rate was 200m3/d, the plume was to be effectively restrained; for leakage-proof barriers, it might effectively protect the groundwater of sensitive objects within an extent time range. But for the continuous point source, the plume was still to circle the leakage-proof barrier; when discharge rate of drainage ditches was 170.26 m3/d, the plume was effectively controlled; the comprehensive method combining ground-harden with drainage ditches could get the best effect in controlling contaminant diffusion, and the discharge rate was to be reduced to 111.43 m3/d. Therefore, the comprehensive remedial alternative combining ground-harden with drainage ditch will be recommended for preventing ground-water contamination when leachate leakage has happened in unregulated landfills.展开更多
基金supported by the Mega-projects of Science Research for Water Environment Improvement (No. 2009ZX07106-001-005-01)the National Nature Science Foundation of China (No. 71103166)
文摘Lake eutrophication （LE） has become an increasingly severe environmental problem recently. However, there has been no nutrient standard established for LE control in many developing countries such as China. This study proposes a structural equation model to assist in the establishment of a lake nutrient standard for drinking water sources in Yunnan-Guizhou Plateau Ecoregion （Yungui Ecoregion）, China. The modeling results indicate that the most predictive indicator for designated use-attainment is total phosphorus （TP） （total effect =-0.43）, and chlorophyll a （Chl-a） is recommended as the second important indicator （total effect =-0.41）. The model is further used for estimating the probability of use-attainment associated with lake water as a drinking water source and various levels of candidate criteria （based on the reference conditions and the current environmental quality standards for surface water）. It is found that these candidate criteria cannot satisfy the designated 100% use-attainment. To achieve the short-term target （85% attainment of the designated use）, TP and Chl-a values ought to be less than 0.02 mg/L and 1.4 μg/L, respectively. When used as a long-term target （90% or greater attainment of the designated use）, the TP and Chl-a values are suggested to be less than 0.018 mg/L and 1 μg/L, respectively.
文摘A groundwater flow and solute transport model was developed using Visual Modflow for forecasting contaminant transport and assessing effects of remedial alternatives based on a case study of an unregulated landfill leachate-contaminated groundwater in eastern China. The results showed that arsenic plume was to reach the pumping well in the downstream farmland after eight years, and the longest lateral and longitudinal distance of arsenic plume was to reach 200 m and 260 m, respectively. But the area of high concentration region of arsenic plume was not to obviously increase from eight years to ten years and the plume was to spread to the downstream river and the farmland region after 20 years; while the landfill＇s ground was hardened, the plume was not to reach the downstream farmland region after eight years; when the pumping well was installed in the plume downstream and discharge rate was 200m3/d, the plume was to be effectively restrained; for leakage-proof barriers, it might effectively protect the groundwater of sensitive objects within an extent time range. But for the continuous point source, the plume was still to circle the leakage-proof barrier; when discharge rate of drainage ditches was 170.26 m3/d, the plume was effectively controlled; the comprehensive method combining ground-harden with drainage ditches could get the best effect in controlling contaminant diffusion, and the discharge rate was to be reduced to 111.43 m3/d. Therefore, the comprehensive remedial alternative combining ground-harden with drainage ditch will be recommended for preventing ground-water contamination when leachate leakage has happened in unregulated landfills.
