Advanced Materials Research Vols. 726-731

Abstract: Surface water samples of two sections were respectively collected from one side to the other side of Honghu Lake, China, in order to detect the concentrations and distribution of HCHs in the region. The concentrations of total HCHs (the sum of α-HCH, β-HCH,γ-HCH and δ-HCH) in surface water of Honghu Lake ranged from 0.94 to 7.04 ng/L. The highest concentration of HCHs in water was near a shipping traffic path. HCHs were derived mainly from agricultural runoff around Honghu Lake and release of the sediments. Among four component compounds of HCHs, γ-HCH was major contributor in the water, which suggested that lindane may have been used recently around Honghu Lake.

Abstract: In this study, the biases and uncertainty of TRMM 3B42 estimates are investigated over the Huai-River Basin during the summer season in 2010. TRMM products of 3B42RT, 3B42V6 and 3B42V7 are cross-compared to Chinese Precipitation Analyses Products (CPAP) as the reference. It is found that the distribution of bias is closely depend on the terrain with the dry bias locates at hills/mountains and wet bias lies on the plains area. It is concluded that the bias may be caused by the defect of TRMM algorithm which cannot discern different types of precipitation. 3B42V7 product shows the best improvement in reducing both wet and dry bias; it also appears small uncertainty on summer season precipitation estimate.

Abstract: In order to strengthen the monitoring and control of the groundwater quality, the groundwater of Hetang and Longtan water source regions in Beihai city was taken as example to evaluate the groundwater quality. PH, Total dissolved solids, Chloride, Iron, Nitrate, Ammonia- nitrogen, Cyanide, Mercury, Cadmium, Lead and so on were selected as the main factors of water quality evaluation. Single component and comprehensive evaluation methods were used to analyze the class and change trend of groundwater quality. The results showed that groundwater quality of Longtan was slightly better that of Hetang. F value of these two water source regions varied from 2.14 to 2.19 and met the classⅡ, which showed that the groundwater quality of Beihai City was good.

Abstract: The hydrodynamic field distribution had a great influence on the expression form of water eutrophication and the process of algae bloom in lake and reservoir, especially for tributary bay of reservoir. The heterogeneity always appeared in the aquatic ecosystem which caused by the distinct difference of the hydraulic characteristic along the longitudinal direction of river. On this account, it is the guiding foundation for district comprehensive ecological improvement to understand water area hydraulic characteristic. A model was developed for the typical tributary Three Gorges Reservoir Xiangxi bay analysis using numerical method under the difference hydrodynamic factors circumstances. Finally, conclusions are summarized: The main impact factor of Xiangxi Bay hydraulic characteristic is the water level before dam which revealed the lower the level, the greater the flow rate, and with further distance increasing from the main stream ,the larger amplitude of velocity variation; moreover, the affected area by velocity of upstream water level fluctuating is ranging from transition region to the following area, the influence degree is proportional to the velocity that higher flow rate cause deeper affected degree. Results of our proposed model applications analysis procedure are given to provide the reference for establishing the scheme of ecologic regulation.

Abstract: This paper takes the Ligezhuang Area in the downstream of the Dagu River as the typical study case, and the groundwater samples are analyzed scientifically and systemically, then the descriptive statistics, the piper diagram and the mass balance simulation are used to gain the better understanding of the hydrochemistry characteristics and evolution laws of groundwater. The results show that (1) With the increase of the mineralization degree in the research area, the groundwater chemical types change from Ca Na Mg-HCO₃ SO4 Cl type to NaMg-Cl SO₄ and Na-Cl type.(2) When the groundwater flows from low mineralization area to high mineralization area, it mainly occurs the precipitation of calcite and montmorillonite; the dissolution of dolomite, gypsum, halite, CO₂, chalcedony, fluorite and illite; meanwhile the cation exchange effect. The results will provide a better understanding of the groundwater resources in the region and help the government develop suitable utilization strategies for the groundwater resources.

Abstract: Hydro-geochemistry is important for water disaster controlling as it can be used for either understanding of hydrological evolution or water source discrimination. Groundwater samples from the sandstone aquifer in Xutuan coal mine, northern Anhui Province, China have been collected for major ion chemical analysis to understand the operating mechanism of geochemical processes for variation of groundwater chemistry, which will be useful for improving the understanding of hydro-chemical systems in coal mine. The results suggest that they are medium to slightly (6.8 to 8.64 with an average of 7.61) with high concentration of total dissolved solids (943 and 1362 mg/L with mean of 1171 mg/L)). Most of the groundwater samples are classified as Na- HCO₃-Cl and Na-Cl- HCO₃ types according to their relative concentrations of cations and anions. Correlation between ion concentrations, as well as principle component analysis imply that dissolution of dolomite, halite, gypsum, silicate weathering and ion exchange are responsible for the chemical variations of the groundwater.

Abstract: The characteristics of water temperature and hydrodynamic field in Xiangxi Bay of Three Gorges Reservoir are studied by numerical simulation method. The result shows that the lifting of water level wakened the density current intensity and the vertical mixing of water, and increased the temperature difference between the surface and bottom water. Simultaneously, the dropping of water level enhanced the density current intensity and the vertical mixing of water, and decreased the temperature difference between the surface and bottom water. The numerical modeling is a valid tool in the prediction of the hydrodynamic field in estuary, as a valuable tool in understanding the development and progression of density currents and the influence of scheduling on the hydrodynamic characteristics in the Xiangxi Bay of the Three Gorges Reservoir, therefore, this work could provide helpful supports for nutrient transportation and ecological environmental evaluation.

Abstract: Effect on hydrodynamic and sedimentary environment is the key problem of gate construction at tidal estuaries. It cites an instance with the gate of HY River in Sanmen Bay. Based on analyzing the character of the water and sediment, the 2D mathematical model was established. Based on triangle grid and finite volume method, the shallow flow model is examined by 10 tidal level stations and 11 observed synchronous vertical lines. And the comparison between computed result and measured solution demonstrates very good agreement. Though this model, the variation of hydrodynamic law has been studied for the HY gate building. Combining the empirical formulas and fluvial processes analyses, it predicted the sediment siltation law and features of gate construction. And the effect of the key sensitive point has been discussed mainly. The result shows that the tidal flow capacity of downstream area is reduction, and siltation at downstream area of tidal gate. It provides the scientific foundation for the construction of the gates.

Abstract: Both the tidal prism and the water exchange duration can be used as the index of examining the residence time of the pollutants in a semi-enclosed bay, and it is significant to predict the long-term variation of water quality. A 3-dimensional coastal circulation model is used to reproduce the tidal regime in the Shenhu Bay. Simulated tidal currents are examined first, and the then the tidal prism is also compared to observations. Based on the validated simulations, the water exchange duration is further estimated by means of the numerical experiment. The simulations show that the half-exchange and 80%-exchange time are about 14 and 30 d, respectively.

Abstract: In order to investigate the impact of air-sea interaction on the ocean surface mixed layer, Typhoon Winnie (1997) was numerical simulated with a two-way air-sea coupled model MCM (Mesoscale Coupled Model). It shows that the Sea Surface Temperature (SST) decreases over a large area with a magnitude up to 4°C. The sea temperature at 30-50 m depth increases about 1°C corresponding to the surface cooling. Moreover, the oceanic mixed layer depth deepens by 20-30 m. It can be included that these variations in the upper ocean are mainly due to vertical mixing induced by the wind stress of the typhoon.