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631.
区域环境问题和区际环境协作 总被引:5,自引:0,他引:5
本文阐述了区域环境问题的形成机制和区域间环境影响机制 ,提出进行区际环境协作加强区际环境调控以解决区域环境问题的新思路。 相似文献
632.
Huifeng Liu Guohua Liu Ya Li Xing Wu Dan Liu Xiaoqin Dai Ming Xu Fengting Yang 《Environmental science and pollution research international》2016,23(20):20269-20280
Land use conversion and fertilization have been widely reported to be important managements affecting the exchanges of greenhouse gases between soil and atmosphere. For comprehensive assessment of methane (CH4) and nitrous oxide (N2O) fluxes from hilly red soil induced by land use conversion and fertilization, a 14-month continuous field measurement was conducted on the newly converted citrus orchard plots with fertilization (OF) and without fertilization (ONF) and the conventional paddy plots with fertilization (PF) and without fertilization (PNF). Our results showed that land use conversion from paddy to orchard reduced the CH4 fluxes at the expense of increasing the N2O fluxes. Furthermore, fertilization significantly decreased the CH4 fluxes from paddy soils in the second stage after conversion, but it failed to affect the CH4 fluxes from orchard soils, whereas fertilizer applied to orchard and paddy increased soil N2O emissions by 68 and 113.9 %, respectively. Thus, cumulative CH4 emissions from the OF were 100 % lower, and N2O emissions were 421 % higher than those from the PF. Although cumulative N2O emissions were stimulated in the newly converted orchard, the strong reduction of CH4 led to lower global warming potentials (GWPs) as compared to the paddy. Besides, fertilization in orchard increased GWPs but decreased GWPs of paddy soils. In addition, measurement of soil moisture, temperature, dissolved carbon contents (DOCs), and ammonia (NH4 +-N) and nitrate (NO3 ?-N) contents indicated a significant variation in soil properties and contributed to variations in soil CH4 and N2O fluxes. Results of this study suggest that land use conversion from paddy to orchard would benefit for reconciling greenhouse gas mitigation and citrus orchard cultivation would be a better agricultural system in the hilly red soils in terms of greenhouse gas emission. Moreover, selected fertilizer rate applied to paddy would lead to lower GWPs of CH4 and N2O. Nevertheless, more field measurements from newly converted orchard are highly needed to gain an insight into national and global accounting of CH4 and N2O emissions. 相似文献
633.
X. C. Cong G. S. Yang J. H. Qu M. X. Dai 《Environmental science and pollution research international》2016,23(21):21336-21349
A study to investigate the dynamical characteristics of particle matter emissions in a working open yard is conducted in Caofeidian Port of Hebei Province, China. The average diurnal concentrations of the total suspended particulate (TSP) matter and respirable particulate matter (PM10 and PM5) are monitored during the field measurement campaign. Sampling is performed at a regular interval at 8 monitoring stations in the yard with normal industrial activities. The average TSP, PM10 and PM5 concentrations range from 285 to 568, 198 to 423 and 189 to 330 μg.m-3 in the yard, respectively. The linear regression correlation coefficient of TSP/PM10 and TSP/PM5 is 0.95±0.01 and 0.88±0.02, respectively.By using the Spearman correlation method, the wind speed and relative humidity are both weakly correlated with the PM10 and PM5 concentrations according to the measurements. In addition, industrial operation activities, such as vehicular traffic in the yard and the loading time of stackers, are significantly positively correlated with the PM concentration. Using the multivariate regression method, the main parameters influencing the TSP concentration variations are integratedly analysed. The traffic volume is found to be a significant predictor of TSP concentration variation, with the smallest P value (P<0.05).To understand the dynamical characteristics of particle emissions in the yard, the emissions from the truck transports, that is, from unpaved haul roads and from the loading process, are established. Then, the dynamical emission factor (EFD) based on the industrial activities in the yard is proposed. The dynamical emissions average 5.25x105 kg.year-1 and EFD is evaluated to be 0.29 kg.(ton.day)-1 during the measurement period. These outcomes have meaningful implications not only for understanding the dynamical characteristics of particle emissions in the working stockyard but also for implementing effective control measures at appropriate sites in the harbour area. 相似文献
634.
Yu Shi Zhanbin Huang Xiujie Liu Suheryani Imran Licheng Peng Rongji Dai Yulin Deng 《Environmental science and pollution research international》2016,23(7):6168-6178
Heavy metal pollution is a severe environmental problem. Remediation of contaminated soils can be accomplished using environmental materials that are low cost and environmentally friendly. We evaluated the individual and combination effects of humic acid (HA), super absorbent polymer (SAP), zeolite (ZE), and fly ash composites (FC) on immobilization of lead (Pb) and cadmium (Cd) in contaminated soils. We also investigated long-term practical approaches for remediation of heavy metal pollution in soil. The biochemical and morphological properties of maize (Zea mays L.) were selected as biomarkers to assess the effects of environmental materials on heavy metal immobilization. The results showed that addition of test materials to soil effectively reduced heavy metal accumulation in maize foliage, improving chlorophyll levels, plant growth, and antioxidant enzyme activity. The test materials reduced heavy metal injury to maize throughout the growth period. A synergistic effect from combinations of different materials on immobilization of Pb and Cd was determined based on the reduction of morphological and biochemical injuries to maize. The combination of zeolite and humic acid was especially effective. Treatment with a combination of HA?+?SAP?+?ZE?+?FC was superior for remediation of soils contaminated with high levels of Pb and Cd. 相似文献
635.
C. Dai Y.P. Cai H.C. Guo W. Sun Q. Tan 《Journal of the Air & Waste Management Association (1995)》2014,64(6):704-720
This research developed a simulation-aided nonlinear programming model (SNPM). This model incorporated the consideration of pollutant dispersion modeling, and the management of coal blending and the related human health risks within a general modeling framework. In SNPM, the simulation effort (i.e., California puff [CALPUFF]) was used to forecast the fate of air pollutants for quantifying the health risk under various conditions, while the optimization studies were to identify the optimal coal blending strategies from a number of alternatives. To solve the model, a surrogate-based indirect search approach was proposed, where the support vector regression (SVR) was used to create a set of easy-to-use and rapid-response surrogates for identifying the function relationships between coal-blending operating conditions and health risks. Through replacing the CALPUFF and the corresponding hazard quotient equation with the surrogates, the computation efficiency could be improved. The developed SNPM was applied to minimize the human health risk associated with air pollutants discharged from Gaojing and Shijingshan power plants in the west of Beijing. Solution results indicated that it could be used for reducing the health risk of the public in the vicinity of the two power plants, identifying desired coal blending strategies for decision makers, and considering a proper balance between coal purchase cost and human health risk.
Implications:A simulation-aided nonlinear programming model (SNPM) is developed. It integrates the advantages of CALPUFF and nonlinear programming model. To solve the model, a surrogate-based indirect search approach based on the combination of support vector regression and genetic algorithm is proposed. SNPM is applied to reduce the health risk caused by air pollutants discharged from Gaojing and Shijingshan power plants in the west of Beijing. Solution results indicate that it is useful for generating coal blending schemes, reducing the health risk of the public, reflecting the trade-off between coal purchase cost and health risk. 相似文献
636.
Zhaohua Dai Carl C. Trettin Changsheng Li Devendra M. Amatya Ge Sun Harbin Li 《Journal of the American Water Resources Association》2010,46(5):1036-1048
Dai, Zhaohua, Carl C. Trettin, Changsheng Li, Devendra M. Amatya, Ge Sun, and Harbin Li, 2010. Sensitivity of Streamflow and Water Table Depth to Potential Climatic Variability in a Coastal Forested Watershed. Journal of the American Water Resources Association (JAWRA) 1–13. DOI: 10.1111/j.1752-1688.2010.00474.x Abstract: A physically based distributed hydrological model, MIKE SHE, was used to evaluate the effects of altered temperature and precipitation regimes on the streamflow and water table in a forested watershed on the southeastern Atlantic coastal plain. The model calibration and validation against both streamflow and water table depth showed that the MIKE SHE was applicable for predicting the streamflow and water table dynamics for this watershed with an acceptable model efficiency (E > 0.5 for daily streamflow and >0.75 for monthly streamflow). The simulation results from changing temperature and precipitation scenarios indicate that climate change influences both streamflow and water table in the forested watershed. Compared to current climate conditions, the annual average streamflow increased or decreased by 2.4% with one percentage increase or decrease in precipitation; a quadratic polynomial relationship between changes in water table depth (cm) and precipitation (%) was found. The annual average water table depth and annual average streamflow linearly decreased with an increase in temperature within the range of temperature change scenarios (0-6°C). The simulation results from the potential climate change scenarios indicate that future climate change will substantially impact the hydrological regime of upland and wetland forests on the coastal plain with corresponding implications to altered ecosystem functions that are dependent on water. 相似文献
637.
638.
应用径向基函数网络预测有机化合物的生物活性 总被引:2,自引:0,他引:2
为了构建径向基函数 ( RBF)神经网络模型 ,研究一批取代芳香族化合物结构与其大型蚤生物活性参数 log(1/EC50)的关系 ,利用正交最小平方算法逐一选择非线性高斯函数的中心 ,并将归一化参数 σ和容差 ρ作为网络的系统参数 ,通过广程扫描确定其最佳值 .采用种子聚类分析与简单随机抽样相结合的方法将化合物合理地划分为训练集和预测集 .对构建的 RBF网络模型的预测质量进行了不确定性分析 .与回归模型相比 ,RBF网络具有较好的预测性能 ,模型预测的不确定性降低了 30 % . 相似文献
639.
640.
Disinfectants are commonly applied to control the growth of microorganisms in drinking water distribution systems. However, the effect of disinfection on drinking water microbial community remains poorly understood. The present study investigated the impacts of different disinfectants (chlorine and chloramine) and dosages on biofilm bacterial community in bench-scale pipe section reactors. Illumina MiSeq sequencing illustrated that disinfection strategy could affect both bacterial diversity and community structure of drinking water biofilm. Proteobacteria tended to predominate in chloraminated drinking water biofilms, while Firmicutes in chlorinated and unchlorinated biofilms. The major proteobacterial groups were influenced by both disinfectant type and dosage. In addition, chloramination had a more profound impact on bacterial community than chlorination. 相似文献