The changes of nitric oxide production during the growth of Microcystis aerugrinosa

This study characterized the changes of nitric oxide (NO) production during the growth of Microcystis aerugrinosa, a cyanobacterium which usually cause cyanobacterial blooms. Results showed a drastic NO release accompanying with cell density and Chl-a content sharp rises when M. aerugrinosa grew from fifth day to sixth day. Moreover, high N:P ratio accelerated the cyanobacterial growth and NO burst. Sodium nitroprusside, an exogenous NO donor, promoted M. aerugrinosa growth with the optimal concentration of 0.1 mg/L. Experiments by supplementing with sodium nitrite and l-arginine demonstrated NO production in M. aerugrinosa cells was mainly through nitrate reductase (NR) pathway while minorly through NO synthase pathway. All these data suggested M. aerugrinosa produced increasing NO during its growth mainly by NR pathway, during which NO positively regulated the growth of M. aerugrinosa.     

Impact of biogenic emission uncertainties on the simulated response of ozone and fine particulate matter to anthropogenic emission reductions

The role of emissions of volatile organic compounds and nitric oxide from biogenic sources is becoming increasingly important in regulatory air quality modeling as levels of anthropogenic emissions continue to decrease and stricter health-based air quality standards are being adopted. However, considerable uncertainties still exist in the current estimation methodologies for biogenic emissions. The impact of these uncertainties on ozone and fine particulate matter (PM2.5) levels for the eastern United States was studied, focusing on biogenic emissions estimates from two commonly used biogenic emission models, the Model of Emissions of Gases and Aerosols from Nature (MEGAN) and the Biogenic Emissions Inventory System (BEIS). Photochemical grid modeling simulations were performed for two scenarios: one reflecting present day conditions and the other reflecting a hypothetical future year with reductions in emissions of anthropogenic oxides of nitrogen (NOx). For ozone, the use of MEGAN emissions resulted in a higher ozone response to hypothetical anthropogenic NOx emission reductions compared with BEIS. Applying the current U.S. Environmental Protection Agency guidance on regulatory air quality modeling in conjunction with typical maximum ozone concentrations, the differences in estimated future year ozone design values (DVF) stemming from differences in biogenic emissions estimates were on the order of 4 parts per billion (ppb), corresponding to approximately 5% of the daily maximum 8-hr ozone National Ambient Air Quality Standard (NAAQS) of 75 ppb. For PM2.5, the differences were 0.1-0.25 microg/m3 in the summer total organic mass component of DVFs, corresponding to approximately 1-2% of the value of the annual PM2.5 NAAQS of 15 microg/m3. Spatial variations in the ozone and PM2.5 differences also reveal that the impacts of different biogenic emission estimates on ozone and PM2.5 levels are dependent on ambient levels of anthropogenic emissions.     

微波纳米磁粉协同作用处理污泥的研究

将粒径范围在10～20 nm之间的磁粉加入到原污泥中,在微波场中辐射,考察0.5～5 min辐射时间内污泥可生化性能、沉降性能和脱水性能的改善效果.结果表明,在微波和纳米磁粉的协同作用下,污泥快速发生水解,5 min内VSS溶解率达到34.62%,COD溶出率达到13.38%,在显微镜下观察到污泥微生物细胞发生了破裂;...     

改性沸石吸附低浓度氨氮废水及其脱附的研究

采用氯化钠溶液对浙江某地天然沸石改性,以低浓度氨氮废水为处理对象,比较了天然沸石和改性沸石的吸附等温线、吸附动力学和动态吸附,并进行了改性沸石的动态脱附研究.结果表明,沸石的平衡吸附量随着平衡浓度的增大而增大;Freundlich方程比Langmuir方程更好地描述沸石吸附低浓度氨氮废水的行为,改性沸石比天然沸石具有更...     

杂多酸水溶液脱除烟气中SO2的性能研究

合成了H3PMo12O40、H4SiW12O40、H3PW12O40、H4PMo11VO40、H5PMo10V2O40和H6PMo9V3O406种杂多酸,分别采用红外光谱(FT-IR)和X射线衍射(XRD)表征杂多酸的结构,并采用气相色谱仪对6种杂多酸水溶液进行脱硫实验测试.实验结果表明:制备的6种杂多酸具有良好的Ke...     

一株芴降解菌的分离鉴定及其对多环芳烃的降解广谱性研究

从某焦化厂活性污泥中筛选出一株芴的优势降解菌株W-1,经形态学观察、生理生化实验和16S rDNA基因序列分析,确定W-1为粪产碱杆菌.在接种量10%(V/V),初始芴浓度40 mg/L,pH 7.0,温度30℃的条件下,接种培养11 d后,菌株W-1对芴的降解效率达到87.8%.菌株W-1对多环芳烃的降解具有广谱性,...     

新型环保型自来水絮凝剂的研制及应用

根据“有机-无机”絮凝剂相复合协同增效的原则,研制出一种高效的复合环保型自来水絮凝剂,使其处理效果与传统絮凝剂比较,浊度下降0．65％,药剂成本下降9．29％,出水铝离子浓度比传统下降77．3％,无论从产品的性价比还是从环境友好等方面均明显优于传统的自来水絮凝剂,具有明显的经济与环境效益。     

微波改性锆-铝柱撑膨润土对水中Cr(Ⅵ)的吸附

以膨润土为原料,通过微波辐射加热法制备锆-铝柱撑膨润土(MZAPB)吸附剂,研究了 MZAPB 加入量、溶液 pH、吸附时间、温度等因素对 Cr(Ⅵ)吸附效果的影响.研究结果表明:当溶液初始 Cr(Ⅵ)质量浓度为 25mg/L、MZAPB 加入量为 10 g/L、溶液 pH 为 5.6、吸附温度 25℃、吸附时间为 6...     

城市环境承载力分析与评估——以湛江市为例

介绍了环境承载力的涵义以及城市环境承载力的评估方法,以PSR模型研究环境压力所对应的环境状态,以此评估城市环境承载状态,并以湛江市为对象,展开城市环境承载力的现状分析,在此基础上对未来不同发展阶段的环境承载力做情景分析,从减压—改善—优化层次上提出湛江市环境承载力提升的对策建议。     

Experimental field estimation of organic nitrogen formation in tree canopies

The content of organic N has been shown in many studies to increase during the passage of rain water through forest canopies. The source of this organic N is unknown, but generally assumed to come from canopy processing of wet or dry-deposited inorganic N. There have been very few experimental studies in the field to address the canopy formation or loss of organic N. We report two studies: a Scots pine canopy exposed to ammonia gas, and a Sitka spruce canopy exposed to ammonium and nitrate as wet deposition. In both cases, organic N deposition in throughfall was increased, but only represented a small fraction (<10%) of the additional inorganic N supplied, suggesting a limited capacity for net organic N production, similar in both conifer canopies under Scottish summertime conditions, of less than 1.6 mmol N m⁻² mth⁻¹ (equivalent to 3 kg N ha⁻¹ y⁻¹).