颗粒物分界层Mie散射激光雷达识别的sigmoid算法

基于成都市2013年6月~2015年5月期间由Mie散射激光雷达探测的大气消光系数廓线资料,发现混合层以上在颗粒物消光和分子消光之间一致存在一个S型的过渡区,利用sigmoid函数对此分布形态进行模拟,通过计算该函数上下曲率最大点所在的高度,据此提出了颗粒物分界层Mie散射激光雷达识别的sigmoid算法.针对该算法模拟效果的分析表明,颗粒物分界层过渡区附近大气消光系数理论廓线和实测廓线保持了高度的相关性,二者在春夏秋冬四季的相关系数（R）分别为0.9971±0.0052、0.9935±0.0167、0.9979±0.0038和0.9990±0.0021（均通过α=0.05的显著性检验）.基于sigmoid算法计算的颗粒物分界层过渡区与成都市温江站探空资料得到的逆温层之间存在很好的对应关系.     

普伐他汀的光催化降解性能及机理研究

通过水热法合成Bi₂WO₆,并利用XPS,XRD,BET,UV-Vis和SEM等方法对样品进行了表征;通过光催化性能实验考察了Bi₂WO₆投加量,溶液pH值对普伐他汀（PR）降解效果的影响;通过自由基捕获实验及中间产物的鉴定探明了Bi₂WO₆光催化降解PR过程的主要活性自由基,中间产物及降解机理,并采用发光细菌急性毒性试验评估了PR降解前后的毒性.结果表明,所制备的Bi₂WO₆是由大量纳米片组成的正交晶系花瓣状微球,各元素物质的量比为Bi：W：O=2.5：1：6.7,比表面积为26.67m²/g,带隙能为2.74eV;光催化性能结果表明,对于10mg/L PR,当溶液pH=6.5,Bi₂WO₆投加量为0.4g/L时降解效果最佳,降解率可达80.6%,矿化度为40.2%;自由基捕获实验结果表明降解过程中h⁺起主要的氧化作用,·OH和·O₂^-的氧化起辅助作用.基于活性自由基和中间产物的鉴别结果提出了Bi₂WO₆光催化降解PR的机理,即以h⁺为主,·OH和·O₂^-为辅联合攻击PR分子中C－C键,C＝C双键,酯键等化学键,进而将其分解为易降解小分子有机物.另外,毒性测试结果表明PR经光催化降解后的小分子产物与PR原液相比毒性并没有增强.     

海洋环境低水位加速腐蚀研究进展

以海洋环境中一个非常重要的局部腐蚀形式——低水位加速腐蚀(ALWC)为对象,自其检测、发生原因、防护三个方面就国内外的文献报告进行综述分析。在检测方面,首先介绍了常用的宏观观察这一被动形式,并突出其特征,然后介绍了利用海水中可溶性无机氮含量作为ALWC发生概率预测这一主动形式,分析其优势与不足。在发生原因方面,在对将ALWC认定为一种典型的微生物腐蚀(MIC)形式的认知过程进行介绍之后,重点分析了微生物对ALWC作用机制不清晰的原因,并建议在后续研究中突出动态演变过程,结合高通量测序等分子生物学技术,确定在不同的阶段影响ALWC的关键微生物,且进一步在大气-海水体系下研究典型菌株及其协同作用的影响,提出微生物对ALWC的作用机制。在防护方面,根据新建和已建钢结构设施分别对传统和针对ALWC所具有的MIC与局部腐蚀特性的新型高效防护方法进行了介绍,并分析了防护方法的优缺点。     

A Variance Estimator for Constrained Estimates of Change in Relative Categorical Frequencies

Consistent estimators of change and state becomes an issue when sample data come from a mix of permanent and temporary observation units. A joint maximum likelihood estimator of state and change creates estimates of state that depend on antecedent viz. posterior survey results and may differ from estimates of state derived from a single-date analysis of the sample data. A constrained estimator of change in relative categorical frequencies that eliminates this potential inconsistency is proposed and a model based estimator of their sampling variance is developed. The performance of the constrained estimator is quantified against six criteria and a joint maximum likelihood estimator in simulated sampling from 15 populations with three combinations of permanent and temporary samples, four to six categorical class attributes, and constant size between sampling dates. Bias of the constrained estimators was negligible but larger than for joint maximum likelihood estimators. Mean absolute deviations and variances of constrained estimators were generally at par with the joint estimators. Constrained estimators of root mean square errors and achieved coverage of nominal confidence intervals of constrained estimators were occasionally better. A generalized variance function for the constrained estimates of change is provided as a computational shortcut.     

新疆生态功能区划初探

“新疆生态功能区划”参考了“中国综合生态环境区划方案”，以《生态功能区划暂行规程》为依据，充分考虑新疆独特的地理分布格局，将新疆分为5个生态区，18个生态亚区，79个生态功能区。“新疆生态功能区划”对科学有效地管理新疆生态环境，因地制宜地实施保护和治理策略，保证社会经济可持续发展具有重要意义。     

兰州市功能区大气细菌污染和城市绿地系统杀菌效应分析

在测定兰州市城市不同功能区和不同类型绿地系统空气细菌数量的基础上,分析了各功能区空气细菌污染状况,以及人流量和车流量与空气细菌数量之间的关系;探讨了不同绿地系统的杀菌效应,指出各绿地系统杀菌能力:乔、灌、草>乔、灌>草、灌>草坪。     

Using improved neural network model to analyze RSP,NOx and NO2 levels in urban air in Mong Kok,Hong Kong

As the health impact of air pollutants existing in ambient addresses much attention in recent years, forecasting of airpollutant parameters becomes an important and popular topic inenvironmental science. Airborne pollution is a serious, and willbe a major problem in Hong Kong within the next few years. InHong Kong, Respirable Suspended Particulate (RSP) and NitrogenOxides NO_x and NO₂ are major air pollutants due to thedominant diesel fuel usage by public transportation and heavyvehicles. Hence, the investigation and prediction of the influence and the tendency of these pollutants are ofsignificance to public and the city image. The multi-layerperceptron (MLP) neural network is regarded as a reliable andcost-effective method to achieve such tasks. The works presentedhere involve developing an improved neural network model, whichcombines the principal component analysis (PCA) technique and theradial basis function (RBF) network, and forecasting thepollutant levels and tendencies based in the recorded data. Inthe study, the PCA is firstly used to reduce and orthogonalizethe original input variables (data), these treated variables arethen used as new input vectors in RBF neural network modelestablished for forecasting the pollutant tendencies. Comparingwith the general neural network models, the proposed modelpossesses simpler network architecture, faster training speed,and more satisfactory predicting performance. This improvedmodel is evaluated by using hourly time series of RSP, NO_x and NO₂ concentrations collected at Mong Kok Roadside Gaseous Monitory Station in Hong Kong during the year 2000. By comparing the predicted RSP, NO_x and NO₂ concentrationswith the actual data of these pollutants recorded at the monitorystation, the effectiveness of the proposed model has been proven.Therefore, in authors' opinion, the model presented in the paper is a potential tool in forecasting air quality parameters and hasadvantages over the traditional neural network methods.     

空气细颗粒物(PM2.5)污染特征及其毒性机制的研究进展

细颗粒物(PM2.5)是指空气动力学直径≤2.5μm的颗粒物,其表面吸附大量的有毒有害物质,并可通过呼吸沉积在肺泡,甚至可通过肺换气到达其他器官.由于细颗粒物的重要性,美国EPA已经于1997年颁布了细颗粒物的空气质量标准,年均值为0.015mg/m3,日均值为0.065mg/m3,然而我国至今仍未制定细颗粒物空气质量标准.颗粒物上吸附的化学组分主要可分成自然来源及燃煤或燃油等人为污染来源两大类,特别是来自工业性和居住区燃煤及汽车燃油尾气.空气细颗粒物污染表现为形态各异、成分复杂等特征.细颗粒物有明显的毒性作用,可引起机体呼吸系统、免疫系统等较为广泛的损害.细颗粒物与心肺疾病密切相关,如增加入院率、急诊次数、呼吸疾病及症状增加、肺功能下降,甚至于过早死亡.简要概述了细颗粒物的污染特征及其毒性机制研究进展.     

赤潮研究的现状与展望

赤潮已成为一种严重的海洋灾害 ,引起沿海国家和地区的重视 ,并成为研究的热点。文章从赤潮发生的机理、赤潮管理与减灾等方面论述了赤潮研究的现状 ,并提出今后研究的重点。     

太湖水质氮素质量浓度时空差异特征及影响因素分析

通过对2014—2016年湖体水质中氮素质量浓度分析,结合出入湖总氮浓度、水量、湖体水生生态等影响因素,发现太湖水体中总氮浓度呈现逐年下降的趋势,各监测点位总氮为0.530 mg/L～5.51 mg/L,时空分布不均,差异明显。时间上,总氮浓度表现为春季最高,夏季和秋季最低,且月均值变化曲线呈现出规律的正弦函数波形。空间上,总氮浓度大致表现出由西部湖区向东部湖区递减的趋势,呈现西部湖区﹥北部湖区﹥南部湖区﹥湖心区﹥东部湖区。要改善湖体水质,不仅要切断污染源,而且要加强水生生态功能修复。