Water Quality Modeling for a Typical Urban Lake Based on the EFDC Model

Urban lakes are typically characterized by fragile ecological capacities and complex management of their hydrospheric ecosystems. The aims of this study are to establish a reliable hydrodynamic-water quality model for an urban lake, to investigate the responses of water quality to different extreme hydrological conditions associated with rainstorms, and to explore the results from different modeled scenarios surrounding the pollution threats associated with a sewage leak. A three-dimensional hydrodynamic water quality model was developed in this study. The model was calibrated and validated using observed data. The model results agreed well with the observed data, and the averaged relative root mean-squared error (RRMSE) for all of the compared variables was 33.3 %. The validated model was applied to analyze water quality responses for different extreme historical rainfall scenarios from January 1, 2012 to December 31, 2012. The model results indicate that for Lake Tianyinhu, rainstorms adversely affect water quality due to larger nutrient loads, generated by larger rainfall events, and the limited water storage capacity of the lake. Moreover, the responses of water quality to sewage leak events were studied through four scenarios with different leak intensities and durations. The model results indicate that sewage leaks have measureable negative effects on water quality and that it is vital to inspect and promptly eliminate any possible leaks within pipes surrounding the lake. This study may provide a useful tool for hydrological ecosystem protection and management techniques for similar urban lakes.     

Invasive species change detection using artificial neural networks and CASI hyperspectral imagery

For monitoring and controlling the extent and intensity of an invasive species, a direct multi-date image classification method was applied in invasive species (salt cedar) change detection in the study area of Lovelock, Nevada. With multidate Compact Airborne Spectrographic Imager (CASI) hyperspectral data sets, two types of hyperspectral CASI input data and two classifiers have been examined and compared for mapping and monitoring the salt cedar change. The two types of input data are all two-date original CASI bands and 12 principal component images (PCs) derived from the two-date CASI images. The two classifiers are an artificial neural network (ANN) and linear discriminant analysis (LDA). The experimental results indicate that (1) the direct multitemporal image classification method applied in land cover change detection is feasible either with original CASI bands or PCs, but a better accuracy was obtained from the CASI PCA transformed data; (2) with the same inputs of 12 PCs, the ANN outperforms the LDA due to the ANN’s non-linear property and ability of handling data without a prerequisite of a certain distribution of the analysis data.     

土壤性质在出生缺陷环境风险中的指示作用

为研究土壤性质在出生缺陷环境风险中的指示作用,考虑了区域人口分布和疾病空间结构,使用Bayesian方法,对山西省和顺县连续4年的神经管畸形发生的数据进行了处理,并使用非参数统计的方法,结合土壤环境过程机理,对土壤的理化性质和出生缺陷的环境风险做了系统分析. 结果表明:土壤的机械组成,阳离子交换量(CEC),pH,有机质含量及碳酸钙含量都与神经管畸形发生率显著相关. 土壤砂粒含量高的地区,神经管畸形发生的风险会显著增加;土壤粘粒含量高的地区,神经管畸形发生的风险会显著降低. 土壤阳离子交换量高的地区,神经管畸形发生的风险会显著降低. 在偏碱性土壤且pH较高的地区,神经管畸形发生的风险会显著降低.在有利于土壤提供有效形态重金属及稀土元素的环境条件下,神经管畸形发生率会显著提高.在影响神经管畸形发生的环境因素中,土壤介质中各形态元素的有效含量比其总量具有更强的指示作用.      

Investigation of exhaled pollutant distribution in the breathing microenvironment in a displacement ventilated room with indoor air stability conditions

This study experimentally studied the dispersion of exhaled pollutant in the breathing microenvironment (BM) in a room equipped with a displacement ventilation (DV) system and indoor air stability conditions (i.e., stable and unstable conditions). The vertical temperature differences and the carbon dioxide (CO₂) concentration in the BM were measured. Results show that when DV is combined with the stable condition (DS), pollutant tends to accumulate in the BM, leading to a high pollutant concentration in this region. Whereas, when DV is combined with the unstable condition (DU), pollutant diffuses to a relatively wider area beyond the BM, thus the pollutant concentration in the BM is substantially reduced. Moreover, increasing the flow rate can reduce the pollutant concentration in the BM of the DS but yields little difference of the DU. In addition, personal exposure intensity increases with time, and the DS has a relatively higher increase rate than DU. The results suggest that indoor air stability will affect the performance of DV systems. DS will lead to a higher health risk for people when they stay in the indoor environment with pollutant sources, and DU is recommended for minimizing pollutant level in the BM in order to reduce the pollutant concentration and providing better air environments for the occupants.     

双酚A分子印迹聚合物的制备及其在水相中的吸附性能

以双酚A (BPA)为模板分子,α-甲基丙烯酸为功能单体,二乙烯基苯为交联剂,偶氮二异丁腈为引发剂,甲苯为溶剂,沉淀聚合法制备了BPA的分子印迹聚合物(MIPs).聚合物在BPA超纯水溶液中的吸附实验结果表明,MIPs对BPA的吸附量和吸附速率大于非印迹聚合物.通过Scatchard分析,MIPs对BPA的最大表观吸附...     

Apolipophorin III and transmission electron microscopy as toxicity indicators for harmaline and tea saponin in Spodoptera exigua (Noctuidae: Lepidoptera)

Apolipophorin III, traditionally known for lipid transport in insects is fairly established as toxicity indicator against harmaline and tea saponin during this study. Apolipophorin III expressed in the hemolymph and midgut tissues of 3rd, 4th, 5th larval instars and pupae of Spodoptera exigua. Apolipophorin III presence was further confirmed by achieving its partial cDNA (Genbank accession no. FJ606822) of 448 bp. qRT PCR revealed that tea saponin resulted in significant reduction of gene expression in 3rd and 4th larval instars but increased in 5th instar as compared to control. Harmaline caused gradual increase of gene expression in 3rd, 4th and 5th instars after feeding on the treated diet. Fifth instar larvae synonymously resulted in the highest gene expressions against both the biochemicals. After the injection of harmaline and tea saponin abrupt increase in gene expression of 4th, 5th larval instar and pupae was observed as compared to control treatment. Transmission electron microscopy of midgut epithelium after being fed with harmaline and tea saponin depicted certain cytological changes. Harmaline treatment lead to cytoplasm vacuolization, mitochondrial disruption, spherocrystals with concentric layers, irregular nucleus and floating nuclei in cytoplasm. Tea saponin treatment resulted in denser cytoplasm, higher intracellular osmotic concentration and reduced complement of apical microvilli. Cells were found to have only a few mitochondria and glycogen deposits in comparison to control treatment.     

Correlation between PM concentrations and aerosol optical depth in eastern China

Using one year of Aerosol Optical Depth (AOD) derived from Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite and particular matter (PM) contents measured at eleven sites located mostly in the eastern China in 2007, the relationship between columnar AOD and hourly and daily average (DA) PM were established. The peak AOD observed from MODIS was generally consistent with the surface PM measurements in eastern China, where Zhengzhou had the maximum annual mean PM₁₀ of 182.1 μg m^?3, while Longfengshan had the minimum annual mean of 38.1 μg m^?3. Ground level observations indicated that PM concentration varies widely across different regions, which was mainly due to the difference in weather conditions and anthropogenic emissions. The coarse particles accounted for the main air pollution in Zhengzhou and Benxi whiles the fine particles, however, were the main constituents in other sites. Results showed that MODIS AOD (averaged over the box of 5 × 5 and 3 × 3 pixels) had a better positive correlation with the coincident hourly average (HA) PM concentration than with DA due to diurnal variation in PM mass measurements. After correcting AOD for relative humidity (RH), the correlation did not improve significantly, suggesting that the RH was not the main factor affecting the correlation of PM with AOD. The statistical regression analysis between MODIS AOD and PM mass suggested that the satellite-derived AOD is a useful tool for mapping PM distribution over large spatial domains.     

Two-stage biodegradation coupled with ultrafiltration for treatment of municipal landfill leachate

The municipal landfill leachate was treated in a hydrolysis–acidification reactor (HAR)/aerobic bio-contact oxidation reactor (ABOR) following a pretreatment with ultrafiltration (UF) membrane. Experiments were conducted continuously for 44 days at a constant flow rate of 20 l d⁻¹ and organic loading rates (OLRs) from 0.75 to 1.5 kgCOD m⁻³ per day. The results showed that COD of the leachate steadily decreased from 20,015 mg l⁻¹ to less than 3000 mg l⁻¹, and NH₄-N decreased from 368.6 mg l⁻¹ to 259.3 mg l⁻¹ in the UF process. The COD and NH₄-N removal efficiency of HAR was 56.7% and 27.7%, and that of ABOR was 94.6% and 86.7%, respectively. The total COD and NH₄-N removal efficiency reached 99.6% and 93.2%, respectively. UF and HAR played a critical role in raising the biodegradability of the landfill leachate, while ABOR had an important function on removing the dissolved NH₄-N in leachate.     

危险点的分析、预控在设备检修中的应用

飞来峡水利枢纽共安装了4台灯泡贯流式水轮发电机组。危险点分析、预控工作与安全性评价应用现代化的管理方法和手段贯彻“安全第一,预防为主”的方针,推动安全生产全员、全方位、全过程闭环管理的方法。     

车用环保甲醇柴油制备工艺的研究

根据微乳液理论和甲醇分子结构的特点,选择出适合制备甲醇柴油微乳燃料的助溶剂和助溶表面活性剂,并对乳化过程进行了机理和实验研究。由实验得出微乳燃料最佳制备工艺条件为：常温下甲醇、0#柴油、脂肪酸甲酯、正丁醇分别占乳液质量的12%、50%、30%和8%,搅拌速度300 r/mim,乳化时间3 min。对最佳配方所得样品的粒径分析发现,粒径大小在30～140 nm之间,微乳液具有较好的高温稳定性、低温稳定性和机械稳定性,外观保持均一,1年内无沉淀或分层析出。