盐城湿地建设项目对越冬水鸟生境的累积生态影响评价研究

选择盐城湿地的建设项目为研究对象.选取丹顶鹤、雁鸭类和鸻鹬类作为盐城湿地越冬水鸟的代表性物种,选取生境景观类型、土地占用以及人为干扰作为影响因子,利用ArcGIS分别做出三个影响因子对于越冬水鸟生境影响分布图,采用图形叠置法对各因子生境影响进行叠加.据此,以越冬水鸟适宜生境面积的变化来反映建设项目对于越冬水鸟的累积生态影响.并且提出设立鸟类监测救护站和栖息地补偿等生态措施来减少建设项目的影响.     

高压水射流冲击煤体损伤的数值模拟研究

为研究高压水射流破煤过程中煤体的损伤状态及压力的分布状态,论文采用J-H-C含损伤本构模型,水射流采用Bridgman状态方程,通过拉格朗日-欧拉有限元法模拟计算高压水射流冲击煤体的损伤机制,得出了煤体在高压水射流冲击作用下不同时刻的损伤变化情况。结果表明,煤体在高压水射流作用下,在接触点两边形成"肺叶状"负压力区,煤体所受压力逐渐减小;冲击速度和产生的损伤随时间变化逐渐减小,损伤主要集中于坑洞底部。     

无机-有机柱撑蒙脱石吸附对硝基苯酚的热力学与动力学特征研究

研究了无机-有机柱撑蒙脱石吸附对硝基苯酚的热力学特征,Freundlich和Langmuir等温方程都能较好地描述吸附曲线,所以其吸附机理主要以表面吸附为主;在对硝基苯酚的平衡吸附过程中,焓变ΔH绝对值小于30KJ/mol,表明吸附过程中可能同时存在疏水键力、偶极间力、氢键力、范德华力的作用。比较研究了对硝基苯酚在无机-有机柱撑蒙脱石上吸附的四种动力学模型,在吸附进行前30min,一级动力学方程最为理想,根据其相关系数可以求得各实验温度下的表观吸附速率常数Kd和吸附活化能Ea。     

水解酸化-深井曝气-脱气-二沉池工艺处理印染废水工程实例

对某纺织企业污水站进行改造,由于用地紧张,将污水站生物接触氧化工艺改造成深井曝气工艺,大大节约了土地资源,并且有较好的处理效果。深井曝气具有抗冲击能力强、氧利用率高、管理方便、运行稳定、低能耗、占地省等优点,因此越来越多的被应用到印染纺织废水的处理中。但也存在着缺点:污泥龄比较短,硝化效果比较差,导致脱氮能力不强,污泥的稳定程度比低负荷工艺低,钻井技术要求也相对较高等。总之,深井曝气工艺是一种先进的处理工业废水的新工艺,若能扬长避短,将会得到广泛应用。     

改善烟气脱硫装置浆液池响应特性方法研究

通过对现有的烟气脱硫系统吸收塔浆液池在运行过程中浆液pH值响应过程的分析,针对现有脱硫装置浆液池pH值响应滞后导致的一系列问题,提出了改善烟气脱硫装置浆液池响应特性的措施方案,结合工程实例说明了通过在浆液池内加装浆液气氛控制系统使得pH值响应更为及时,并使浆液池内pH值分布满足浆液池功能要求。保证脱硫装置的安全稳定高效运行,有效降低运行消耗。     

测定水中氰化物影响条件的实验研究

异烟酸—吡唑啉酮分光光度法在实际应用中稳定性较差,通过对显色反应条件的试验,以及对其他影响因素的分析,探索测定了反应的最佳条件。     

Evaluation on exposures to particulate matter at a junior secondary school: a comprehensive study on health risks and effective inflammatory responses in Northwestern China

Air pollutant measurement and respiratory inflammatory tests were conducted at a junior secondary school in Xi’an, Northwestern China. Hazardous substances including particulate matters (PMs), black carbon (BC) and particle-bounded polycyclic aromatic hydrocarbons (PAHs) were quantified both indoors and outdoors of the school. Source characterization with organic tracers and particle-size distribution demonstrated that the school’s air was mostly polluted by combustion emissions from the surrounding environment. The evaluation of health assessment related to air quality was conducted by two methods, including potential risk estimation of air pollutants and direct respiratory inflammatory test. The incremental lifetime cancer risks associated with PAHs were estimated and were 1.62 × 10⁻⁶ and 2.34 × 10⁻⁶, respectively, for indoor and outdoor fine PMs. Both the values exceeded the threshold value of 1 × 10⁻⁶, demonstrating that the carcinogenic PAHs are a health threat to the students. Respiratory inflammatory responses of 50 students who studied in the sample classroom were examined with a fractional exhaled nitric oxide (FeNO) test, with the aid of health questionnaires. The average FeNO concentration was 17.4 ± 8.5 ppb, which was slightly lower than the recommended level of 20 ppb established by the American Thoracic Society for children. However, a wide distribution and 6% of the values were > 35 ppb, suggesting that the potentials were still high for eosinophilic inflammation and responsiveness to corticosteroids. A preliminary interpretation of the relationship between air toxins and respiratory inflammatory response demonstrated the high exposure cancer risks and inflammatory responses of the students to PMs in the city.

     

Characteristics of N2O emission from Medicago sativa stands and its response to nitrogen fertilizers in the Longdong dryland Plateau北大核心CSCD

Nitrous oxide (N2O) is one of the potent greenhouse gases (GHG) that depletes the stratospheric ozone. Nitrogen fertilizers are considered to be a major source of nitrous oxide (N2O) emissions from arable soils. To investigate the characteristics of N2O emission, its influencing factors, and its response to nitrogen application in dry grassland in the Loess Plateau, one of the most intensively used agricultural regions in China, we conducted a field trial with two treatments including N0 (0 kg hm-2) and N150 (150 kg hm-2) at the Qingyang Loess Plateau grassland agricultural research station of Lanzhou University. An LGR-N2O/CO gas analyzer was used to monitor the emissions. The results showed that the N2O fluxes of the N0 and N150 treatments during the monitoring period were -0.0036 and 0.0118 mg m-2 h-1, respectively; the flux in case of the N150 treatment was significantly higher than that for the N0 treatment. The N2O emission flux has a distinct diurnal variation characteristic, which first showed the trend of decreasing and then increasing. Regression analysis indicated a significant positive correlation between the N2O flux and the surface soil water content at a depth of 10 cm. The N2O emission flux increased by 131.3%, compared with that during the non-precipitation days. At the same time, the N2O emission flux showed a trend of decreasing with the increase of the surface soil temperature at a depth of 10 cm. The daily emission characteristics indicated that there may be a significant underestimation of the N2O flux at the daily or longer time-scale, based on the N2O flux value measured at 9:00-11:00. In summary, the N2O emissions from the sown alfalfa grassland of the eastern Gansu are strongly affected by precipitation and nitrogen application and have obvious daily dynamic characteristics. It is recommended that the accuracy and representativeness of N2O emission flux data be enhanced by continuous dynamic measurement using the instrument. © 2018 Science Press. All rights reserved.     

Biomarkers as tools to assess the chronic toxicity of ammonia in the juvenile Mugil cephalus

With juvenile fish as the subject, the effects of low concentration ammonia on antioxidant system were studied using Mugil cephalus. Samples of gill and liver tissue were obtained from 0.35, 0.70, 1.5 and 3?mg/L ammonia groups at 0, 5, 10, 15 and 20 days of exposure, at which times the biomarkers were measured. Results showed that gill malondialdehyde (MDA) content exhibited an initial significant increase (p?≤?0.05) at unionised ammonia concentrations of 0.70, 1.5 and 3.0?mg/L on day 5, followed by subsequent declines, while liver MDA levels exhibited significant increases (p?≤?0.05) at unionised ammonia concentrations of 1.5?mg/L starting on day 10 and at 3.0?mg/L starting on day 5. With exposure to ammonia at different concentrations, Na⁺-K⁺-ATPase activity in liver and gill decreased over time. The Na⁺-K⁺-ATPase activity was negatively related to ammonia concentration from 0.70 to 3.0?mg/L. Overall, our results show that MDA and Na⁺-K⁺-ATPase, evaluated here as potential biomarkers of ammonia exposure, exhibited responses to sublethal concentrations of ammonia that were concentration dependent.