Fluent软件在地表水源热泵系统温排水数值模拟中的运用

运用Fluent软件对重庆市嘉陵江化龙桥段瑞安新天地江水水源热泵系统尾水排入受纳水域的过程进行二维数值模拟,选取Fluent中非耦合、隐式求解器对模型内的定常流动进行求解,得出受纳水域受水源热泵系统温排水影响后的温升面积和温度梯度。结果表明:在温排水流量为2.0×103 m3/h、温差为4℃的条件下,计算该水域沿水流方向温升超过1℃的最大影响距离为150.4 m,温升超过1℃的水域面积约为1 525 m2,为模拟江水面积的8.59%。选取1℃温升值作为温升带的边界控制值,并在热泵系统最大负荷工况下,根据W=Q×ΔT计算研究水域热环境容量为19.402 m3.℃/s,剩余热环境容量为17.736 m3.℃/s。根据地表水环境质量标准,该工程温排水量小于受纳水域的热承载力,不会对受纳水域生态环境造成热污染。     

Community structure and biotic integrity of aquatic plants along the North Canal in Beijing北大核心CSCD

Aquatic plants along the North Canal in Beijing were studied to identify the community structure of aquatic plants and vegetation index of biotic integrity (VIBI), and to provide scientific basis for the management and protection of urban rivers. Aquatic plants from 49 sampling sites along the North Canal were investigated during June 2015. Based on the field data, distributing range analysis, discriminatory power analysis, and correlation analysis were used stepwise to select core metrics from candidate metrics to establish the VIBI assessment system. The VIBI value of each sampling site was calculated as the average of the scaled values of all core metrics. Thirty-six aquatic plant species, including 14 hygrophytes, 13 emergent species, 6 submergent species, 2 floating-leaved species, and 1 floating species were collected. Species diversity was low in the North Canal, and no aquatic plants were recorded in 28 sampling sites, of which 9 sampling sites were dried up. Five sites were in excellent condition (VIBI > 0.60), 5 were good (0.60 > VIBI > 0.38), 7 were fair (0.38 > VIBI > 0.23), and 4 were poor (VIBI < 0.23). Based on the distribution of VIBI, Shahe River and Wenyu River upstream, and Fenghe River located in suburbs had a higher VIBI. Downstream tributaries, such as Qinghe River, Bahe River, and Liangshui River, had a lower VIBI. Correlation analysis showed that habitat quality, habitat complexity, and vegetation diversity along riparian zones were the important factors affecting VIBI along the North Canal, Beijing. Aquatic plants along the North Canal showed low species diversity owing to human disturbance. VIBI along tributaries with limited disturbance from human activities was higher; however, VIBI along tributaries disturbed by frequent human activities was lower. © 2018 Science Press. All rights reserved.     

智能供氧系统在污水领域的应用研究

绍兴污水处理厂二期工程采用的是延时曝气工艺,生物氧化池是其核心工艺所在,在实际运行中,生物氧化池中溶解氧的数值波动大,较难实现稳定控制,通常采用滞后调整的控制方式,易造成能耗增加。为合理控制供气量,降低运行成本,利用欧洲的智能供氧技术,在经过小试的基础上,对二期其中一组生物氧化池进行中试,通过对几个月的试验数据进行对比分析,溶解氧控制较为平稳,供风量有所降低,从而实现了安全供氧和经济供氧,推动污水处理厂的精细化操作向纵深化发展。     

Assessment of the red-crowned crane habitat in the Yellow River Delta Nature Reserve, East China

As wildlife habitat is in constant evolution, periodic monitoring is essential to assess its quality. In this study, the change to the red-crowned crane habitat in the Yellow River Delta Nature Reserve was detected from multi-temporal remote sensing data from 1992 to 2008 in a geographic information system. Habitat fragmentation was derived from both physical constraints and human disturbance. The changing habitat quality was assessed against five landscape indices. The results obtained from Landsat TM images indicate that potential habitat shrank 37.9 % during 1992–2001, but recovered 99.4 % by 2008. Suitable habitat shrank by 4,329 ha to a level below that of 1992 despite an increase of 4,747 ha in potential habitat due to an increase of 9,075 ha in fragmented areas. Both landscape indices and the red-crowned crane population reveal that suitable habitat was the most fragmented in 2001, but the least fragmented in 1992. Therefore, it is inadequate to just restore wetland through artificial diversion of channel flow to the Reserve to preserve the crane habitat. Commensurate efforts should also be directed at improving habitat quality by minimizing human activities and spatially juxtaposing water and reed marshes harmoniously inside the Reserve.     

Removal of polycyclic aromatic hydrocarbons from aqueous solution on soybean stalk-based carbon

Soybean [ (L.) Merr.] stalk-based carbons were prepared by phosphoric acid activation at different carbonization temperatures. Characteristics of the prepared carbon, including specific surface area, iodine number, and amount of methylene blue sorption, were determined. Experiments on phenanthrene, naphthalene, and acenaphthene, as representatives of polycyclic aromatic hydrocarbons (PAHs), removal from aqueous solution by the prepared carbon were conducted at different levels of carbon addition. The results indicated that the specific surface area, iodine number, and amount of methylene blue sorption increased with an increase of carbonization temperature. The maximum values were observed at 700°C and were 287.63 m g, 508.99 mg g, and 90.14 mg g, respectively. The removal efficiencies of phenanthrene, naphthalene, and acenaphthene tended to increase with increasing carbon amounts and carbonization temperature. The optimal removal performance was obtained under the experimental conditions of carbon concentrations of 0.04 g 32 mL and carbonization temperature of 700°C, and the removal efficiencies of phenanthrene, naphthalene, and acenaphthene were 99.89, 100, and 95.64%, respectively. The performance of the prepared carbon was superior to that of commercial activated carbon. Additionally, for the same carbon concentrations, the removal efficiency of PAHs on prepared carbons followed the order: phenanthrene > naphthalene > acenaphthene. Results obtained from this work provide some insight into the reuse of an agricultural residue, and also provide a new application for the treatment of PAHs in contaminated water utilizing activated carbon prepared from agricultural residues.     

河北省进一步发展高等教育的初步探讨

河北省高等教育在全国排名榜中相对落后,与人口大省、经济大省不适应,其原因是多方面的。进一步发展高等教育对河北省实现向经济强省、文化强省跨越至关重要,为此河北省应将努力发展高等教育纳入"十二五"规划,适度扩大办学规模;加大投入;分类指导,突出重点,增强特色,推动内涵式发展;办强师资队伍及师德师风建设;鼓励高校开展科技创新。     

Pollution characteristics and health risk assessment of polycyclic aromatic hydrocarbons and nitrated polycyclic aromatic hydrocarbons during heating season in Beijing

Polycyclic aromatic hydrocarbons(PAHs) and their nitrated derivatives(NPAHs) attract continuous attention due to their outstanding carcinogenicity and mutagenicity. In order to investigate the diurnal variations, sources, formation mechanism, and health risk assessment of them in heating season, particulate matter(PM) were collected in Beijing urban area from December 26, 2017 to January 17, 2018. PAHs and NPAHs in PM were quantitatively analyzed via gas chromatography-mass spectrometry(GC-MS). ...     

Dissolution behavior of nutrient elements from dephosphorization slag in the weakly acidic solution

Journal of Material Cycles and Waste Management - Dephosphorization slag is primarily composed of CaO–SiO2–FeO–P2O5 slag system. As it contains abundant valuable components,...     

Synergistic effects of gaseous pollutants on hospital admissions for cardiovascular disease in Liuzhou,China

Previous studies demonstrated that short-term exposure to gaseous pollutants (nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and ozone (O₃)) had a greater adverse effect on cardiovascular disease. However, little evidence exists regarding the synergy between gaseous pollutants and cardiovascular disease (CVD). Therefore, we aimed to estimate the effect of individual gaseous pollutants on hospital admissions for CVD and to explore the possible synergistic effects between gaseous pollutants. Daily hospitalization counts for CVD were collected from January 1, 2014, to December 31, 2015. We also collected daily time series on gaseous pollutants from the Environment of the People’s Republic of China, including NO₂, SO₂, and O₃. We used distributed lag nonlinear models (DLNMs) to assess the association of individual gaseous pollutants on CVD hospitalization, after controlling for seasonality, day of the week, public holidays, and weather variables. Then, we explored the variability across age and sex groups. In addition, we analyzed the synergistic effects between gaseous pollutants on CVD. Extremely low NO₂ and SO₂ increase the risk of CVD in all subgroup at lag 7 days. The greatest effect of high concentration of SO₂ was observed in male and the elderly (≥ 65 years) at lag 3 days. Greater effects of high concentration of O₃ were more pronounced in the young (< 65 years) and female at lag 3 days, while the effect of low concentration of O₃ was greater in male and the young (< 65 years) at lag 0 day. We found a synergistic effect between NO₂ and SO₂ for CVD, as well as between SO₂ and O₃. The synergistic effects of NO₂ and SO₂ on CVD were stronger in the elderly (≥ 65) and female. The female was sensitive to synergistic effects of SO₂-O₃ and NO₂-O₃. Interestingly, we found that there was a risk of CVD in the susceptible population even for gaseous pollutant concentrations below the National Environmental Quality Standard. The synergy between NO₂ and SO₂ was significantly associated with cardiovascular disease hospitalization in the elderly (≥ 65). This study provides evidence for the synergistic effect of gaseous pollutants on hospital admissions for cardiovascular disease.

     

Nitrogen fertilization decrease soil CO2 emission in a rainfed maize field in Northeast China

Environmental Science and Pollution Research - Nitrogen fertilizer has considerable effects on soil carbon fluxes. However, the responses of soil CO2 emission to N fertilizer remain controversial....