Advanced Materials Research Vol. 937

Abstract: In order to improve the erosion effect of jet under submergence condition, experimental studies of erosion generated from the self-excited pulsed jet was carried out by using developed self-excited oscillation nozzle. The erosion volume and depth of pulsed jet were measured and taking mortar block as an erosion part. The results were that the standoff has significant influence on erosion effect. The erosion volume firstly decreases with increases in cavity length and then increases to a peak value. Erosion volume of pulsed jet is significantly higher than that of continuous jet, the erosion depth of two jet has slight difference.

Abstract: The ozone/hydrogen peroxide system has been introduced for the study of degradation of humic acid in water. The removal ratio of TOC in aquatic humic acid solution has been investigated with some reaction parameter like the change of injected concentration of H₂O₂, initial pH of aqueous humic acid and injection time of H₂O₂. And the formation of formaldehyde concentrations in the treatment system processes has been also evaluated with the variation of its concentration. From the experimental results, it has been concluded that the concentrations of H₂O₂ and the initial pH’s in solution in the ozone/hydrogen peroxide system were very important for enhancing the efficiency of degradation of humic acid in water. The formaldehyde was formed less in ozone/hydrogen peroxide system than in ozone alone system.

Abstract: The dynamic characteristics of the self-excited oscillation pulsed jet is tested by using pulsed jet impact variable cross-section beam in submerged conditions and make comparison with continuous jet, analyzing the effects of operating parameters and nozzle structure parameters on the dynamic characteristics of the pulsed jet. The result show that the oscillating frequency of jet decreases with the increase of cavity length while increases with the increase of the pump pressure. The energy of pulsed jet has obvious change with different cavity length.

Abstract: In order to construct the groundwater numerical simulation model, the study area was determined on the basis of the geological and hydrogeological conditions. Taking Feflow as operating platform, combining GIS with Surfer software, a study area of the structure of three-dimensional aquifer model was established, realizing the 3D visualization of a large area of the complex geological content. Combined with the hydrogeological conditions, three-dimensional geological structure of the model further generalization. The result showed that the aquifer of the vertical was generalized into the unconfined aquifer; based on the characteristics of lithology, structure, parameters and distribution of recharge and discharge in groundwater system, the study area groundwater system was characterized by isotropic saturated-unsaturated numerical flow model, and the equilibrium composition of the elements was analysed in study area, the partition of the aquifer hydrogeological parameters was divided, lay the foundation for groundwater numerical model simulation.

Abstract: Groundwater is an important resource, it is used for variety of purposes in the inland river basins of arid western China. In recent years, the utilization ratio of surface water has been raised, the groundwater recharge rate from surface water has been reduced, and the aquifer depletion due to over-exploitation, which has led to the decline of groundwater levels and the degradation of eco-environments in the Shiyang River Basin, especially in Minqin. Therefore, the study on the groundwater levels change in recent years, as well as simulating and predicting groundwater levels in the future have gotten very important. The purpose of this study is to analyze the groundwater level variations of the study area. Basin on a conceptual groundwater model and observation groundwater level data, to establish the groundwater flow model by FEFLOW; simulated and validated the groundwater model. Finally the precision of model was evaluated. It was shown that the model could be used to predict the groundwater levels variation under different hypothesis conditions in Shiyang River Basin, which would provide the effective reference to the rational use and management of the groundwater.

Abstract: Soil washing experiments were carried out with citric acid as washing reagent for the remediation of soils highly contaminated with heavy metals, then activated carbon was used in absorption processing for leaching solution. In this study, the effects of the main operating variables for removal of metals from soils were first discussed. The results showed that 36.% Pb, 47.74% Cu and 61.88% Cd were removed from the contaminated soils by optimizing the washing parameters at citric acid concentration 0.2 mol/l, mixing time 2 h, liquid-soil ratio 20 and solution pH=4, respectively. In the adsorption experiments of leachates, the optimum conditions were found as follows: solution pH=7, mixing time of 2 h, standing time of 60 min and activated carbon dosage of 1g/100ml.

Abstract: The silica, one of the by-products of fluorine industry, contains soluble fluoride which is harmful to the environment. Therefore, a study on fixing soluble fluoride was conducted by hydrothermal method with the silica as raw material and adding hydrated lime (HL), and the nanowires-reticulated calcium silicate with high specific surface area up to 143.8m²/g was prepared at the same time. The prepared calcium silicate was used as adsorbent in the experiments of phosphorus (P) adsorption from aqueous solution, the adsorption capacity, adsorption rate and P removability were characterized. The results show that the preparation conditions affect distinctly the adsorption performances of calcium silicate, especially, the dosage Ca/Si molar ratio. For the optimized calcium silicate sample, the total P adsorption capacity is 125.7mg/g and the exchange rate of Ca²⁺ reaches 95.8%, the P residual concentration is only 0.3mg/L, the saturated adsorption time is 3900 min, when the simulation solution with P concentration of 100 mg/L is treated. The P residual concentration is only 0.1mg/L for the simulation solution of 56.12mg/L.

Abstract: Analysis of marine environment, especially the multi-scale analysis is an efficient means to obtain the environmental situation and guide the environmental management. In this paper, the field data, max, min and average of dissolved inorganic nitrogen (DIN) and phosphate in the Caofeidian marine district, Tangshan Bay is analyzed. The whole water quality situation could be grasped through these analyses. The research results show that the distribution of pollution is disequilibrium and the high value district of pollution exists in research district too.

Abstract: Climate change refers to man-made changes in our climate, which is caused by changes in temperature, precipitation, and CO₂. There is a lot of data coming from all over the world indicating that phenology of garden plants and biodiversity are being impacted by climate change. In the context of climate change, landscape plants can enhance carbon sink function, improve plant design, and mitigate climate change and so on. To determine the impact of these changes on garden plants, scientists would need to strengthen the study of garden plants under global climate change, including different garden type responses to climate change, invaliding species phenology study, extreme weather impacts on landscape plant phenology, the dominant factor of affecting garden plants in different regions, interactions of multiple environmental factors on influence mechanism of garden plants.

Abstract: This paper investigates the seasonal and spatial variations of nutrients, permanganate index and chlorophyll-a of the Xitiaoxi tributaries. The results show that most of nutrients, COD_Mn and chlorophyll-a in dry season are higher than in wet season. The concentrations of TN and NO₃^--N show significant higher in the tributaries dominated by woodland. The contents of TP, TDP and chl-a in tributaries influenced by towns are higher than the tributaries located in farmland and woodland. COD_Mn in mixed-source lands of farmland and towns have the highest concentration, followed by towns and woodland dominated tributaries. The rates of TN/TP indicate that eutrophication in most of tributaries are limited by TP. The correlations between nutrients, COD_Mn and Chl-a indicate the concentrations of organics and microorganism are associated with nitrogen and phosphorus in waters. Land use is the most important factor affecting water quality in tributaries of Xitiaoxi watershed. The values of TDP/TP in towns dominated tributaries are higher than other tributaries. Mixed-source lands are the most important factor affecting NH₄⁺-N values.