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71.
A modified two-dimensional Eulerian air quality model was used to simulate both the gaseous and particulate pollutant concentrations during October 21-24, 2004 in the Pearl River Delta (PRD) region, China. The most significant improvement to the model is the added capability to predict the secondary organic aerosols (SOA) concentrations because of the inclusion of the SOA formation chemistry. The meteorological input data were prepared using the CALMET meteorological model. The concentrations of aerosol-bound species such as NO3^-, NH4^+, SO4^2-, and SOA were calculated in the fine particle size range (〈2.5 μm). The results of the two-dimensional model were compared to the measurements at the ground level during the PRD Intensive Monitoring Campaign (IMC). Overall, there were good agreements between the measured and modeled concentrations of inorganic aerosol components and O3. Both the measured and the modeled results indicated that the maximum hourly O3 concentrations exceeded the China National Air Quality Standard. The predicted 24-h average SOA concentrations were in reasonable agreement with those predicted by the method of minimum OC/EC ratio. 相似文献
72.
Oxidative stress and DNA damages induced by cadmium accumulation 总被引:22,自引:0,他引:22
Experimental evidence shows that cadmium (Cd) could induce oxidative stress and then causes DNA damage in animal cells, however, whether such effect exists in plants is still unclear. In the present study, Vicia faba plants was exposed to 5 and 10 mg/L Cd for 4 d to investigate the distribution of Cd in plant, the metal effects on the cell lipids, antioxidative enzymes and DNA damages in leaves. Cd induced an increase in Cd concentrations in plants. An enhanced level of lipid peroxidation in leaves and an enhanced concentration of H2O2 in root tissues suggested that Cd caused oxidative stress in Vicia faba. Compared with control, Cd-induced enhancement in superoxide dismutase activity was significant at 5 mg/L than at 10 mg/kg in leaves, by contrast, catalase and peroxidaseactivities were significantly suppressed by Cd addition. DNA damage was detected by neutral/neutral, alkaline/neutral and alkaline/alkaline Comet assay. Increased levels of DNA damages induced by Cd occurred with reference to oxidative stress in leaves, therefore, oxidative stress induced by Cd accumulation in plants contributed to DNA damages and was possibly an important mechanism of Cd-phytotoxicity in Vicia faba plants. 相似文献
73.
我国现行环境统计指标体系改进方向 总被引:4,自引:1,他引:3
我国现行环境统计指标体系在指标的选择和可操作性方面存在缺陷和不足,主要表现为污染物排放量的计算方法模糊、污染物排放标准未能得到有效实施、非重点工业排放量取值比例有待调整、污染源调查范围不能与时俱进、环境质量指标体系未纳入环境统计,这些问题需进一步完善,才能更好地适应环境管理工作需要。 相似文献
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本研究首先通过批量实验考察了氢氧化镁对水中磷酸盐的吸附性能,再通过底泥模拟释放实验考察了氢氧化镁覆盖和添加控制底泥中磷向上覆水体释放的效果及机制.结果表明,氢氧化镁对水中磷酸盐具有良好的吸附能力,其投加量的增加有利于水中磷酸盐被其所吸附去除,与Langmuir模型相比,其对水中磷酸盐的等温吸附行为更适合采用Freundlich和Dubinin-Radushkevitch(D-R)模型加以描述.氢氧化镁覆盖可以有效地控制底泥中磷向上覆水体的释放,使得上覆水中SRP浓度处于较低的水平,即使覆盖层的结构完整性受到扰动破坏而导致覆盖材料与表层底泥的混合,氢氧化镁仍然可以有效地控制底泥中磷向上覆水体的释放.氢氧化镁覆盖和添加均可以有效地降低最上层(0~10 mm)底泥间隙水中SRP的浓度,这对于其覆盖和添加有效控制底泥中磷向上覆水体的释放是至关重要的.人工合成的氢氧化镁对水中磷酸盐的吸附性能优于商业购买的氢氧化镁,前者控制水体内源磷向上覆水体释放的效果也优于后者.以上结果显示,氢氧化镁是一种有希望用于控制水体底泥内源磷释放的活性覆盖和改良材料. 相似文献
78.
浅论海洋沉积物标准的几个问题 总被引:1,自引:0,他引:1
简要介绍了海洋沉积物质量基准的研究方法,重点讨论了平衡分配法在确定沉积物基准研究中的广泛用途。理论计算结果与两个海湾多年的监测结果相吻合。 相似文献
79.
The control strategy and simulation of external carbon addition were specially studied in an anoxic-oxic(A/O) process with low carbon: nitrogen(C/N) domestic wastewater. The control strategy aimed to adjust the flow rate of external carbon dosage to the anoxic zone, thus the concentration of nitrate plus nitrite(NOx^- -N) in the anoxic zone was kept closed to the set point. The relationship was studied between the NOx^- -N concentration in the anoxic zone(SNo) and the dosage of external carbon, and the results showed that the removal efficiency of the total nitrogen(TN) could not be largely improved by double dosage of carbon source when SNO reached about 2 mg/L. Through keeping SNO at the level of about 2 mg/L, the demand of effluent quality could be met and the carbon dosage could be optimized. Based on the Activated Sludge Model No. 1 (ASM No. 1), a simplified mathematical model of external carbon dosage was developed, Simulation results showed that PI controller and feed-forward PI controller both had good dynamic response and steady precision. And feed-forward PI controller had better control effects due to its consideration of influent disturbances. 相似文献
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