Mn/Ce复合催化剂湿式氧化降解高浓度吡虫啉农药废水的研究

通过共沉淀法制备了用于湿式氧化吡虫啉农药废水的Mn/Ce复合催化剂,利用BET比表面积测定和XRD对催化剂进行了表征,研究了焙烧温度对Mn/Ce催化剂活性及稳定性的影响,探讨了湿式催化氧化吡虫啉农药废水的适宜反应温度和氧分压.结果表明,Mn/Ce催化剂晶粒细小,晶粒尺寸小于15nm;适当降低焙烧温度,对减小催化剂晶粒、增加比表面积、提高活性有利,但会使金属溶出量增大、稳定性下降;提高反应温度,湿式催化氧化反应速率加快,而氧分压大于1.6MPa后,反应速率不受氧分压影响;使用该催化剂,在温度190℃、氧分压1.6MPa、进水pH为6.21的条件下经120min处理,COD去除率达93.1%;Mn/Ce复合催化剂对湿式氧化吡虫啉农药废水显示较好的活性和稳定性.     

水力空化降解印染废水的初步研究

水力空化技术是一种新的废水处理技术。为探讨操作条件和几何参数等因素对降解的影响,利用多洞孔板水力空化装置对含有若丹明B染色剂的模拟印染废水进行降解试验研究。试验结果表明:水力空化对若丹明B确实有降解作用,处理系统中存在最佳的孔板几何参数和操作运行条件,并且若丹明B的降解速率随修正空化数的减少而增大。     

碳市场对能源结构低碳转型的影响及作用路径

选取中国2000～2018年30个省市的面板数据,构建了能源消费结构低碳化指数,基于多期双重差分、三重差分等方法实证检验碳交易政策与能源消费结构低碳转型之间的关系及异质性影响,并进一步利用多重中介效应模型探讨碳交易政策推动地区能源消费结构低碳转型的作用路径.结果表明:碳交易政策可以显著提升地区能源消费结构低碳化水平且作用效果逐年增强.从作用路径看,“四大效应”激励作用彰显,作用效果由大到小依次为结构优化效应、行为驱动效应、生态创新效应和环保支出效应;从异质性影响看,GDP增速较慢地区的政策实施加快了能源消费结构低碳转型,影响明显高于GDP增速较快地区;碳交易政策对东部地区的正向推动效应显著,对中西部地区无明显促进作用.     

Combining Accuracy Assessment of Land-Cover Maps with Environmental Monitoring Programs

A scientifically valid accuracy assessment of a large-area, land-cover map is expensive. Environmental monitoring programs offer a potential source of data to partially defray the cost of accuracy assessment while still maintaining the statistical validity. In this article, three general strategies for combining accuracy assessment and environmental monitoring protocols are described. These strategies range from a fully integrated accuracy assessment and environmental monitoring protocol, to one in which the protocols operate nearly independently. For all three strategies, features critical to using monitoring data for accuracy assessment include compatibility of the land-cover classification schemes, precisely co-registered sample data, and spatial and temporal compatibility of the map and reference data. Two monitoring programs, the National Resources Inventory (NRI) and the Forest Inventory and Monitoring (FIM), are used to illustrate important features for implementing a combined protocol.     

Introduction of Relative Abundance Distribution (RAD) Indices, Estimated from the Rank-Frequency Diagrams (RFD), to Assess Changes in Community Diversity

Quantifying a relative abundance distribution based on thesampling of a set of species is a widespread problem in ecology.A number of diversity indices have been proposed and used in numerous works in spite of a lack of statistical characteristics and tests of comparison. The relative abundancedistribution can also be described using rank-frequency diagrams but fitting these diagrams to mathematical models such as the Zipf-Mandelbrot model remains problematic. Strong correlation between the Zipf-Mandelbrot model parameters prevent their estimation by optimization algorithm. In light of this, new indices of sampled communities are introduced here. These indices are two linear regression slopes estimated from rank-frequency diagrams. The numerous statistical studies that have been carried out on linear regression models are used to compare sampled communities. These new indices possesscharacteristic properties with an ecological meaning.Correlations between these indices, the Zipf-Mandelbrot modelparameters and an evenness diversity index are examined. Anecological application is made using entomological data as anexample. This example consists of a transect from the edge of apond to a dry forest along which 60,000 insects were sampledfrom six different sampling stations. Using the new indicesdescribed here, station C, located at the edge of that areasubject to influence from the pond, is differentiated from theother stations. This station would seem to present the lowestdegree of niche diversity and the lowest evenness, and recent observations confirm the deterioration of this station.     

中国农村绿色发展绩效的空间差异

运用多种DEA模型与Gini准则相结合的方法,采用2003—2012年中国31个省、直辖市和自治区农村数据,对中国及其各地区农村绿色发展绩效值进行了动态测算与分析,在此基础上,对各省市及其所属地区农村绿色发展绩效值进行排名和分析。结果表明,从全国层面来看,中国农村绿色发展绩效整体上呈现上升趋势,如综合绩效值由2.184上升至2.824,表明全国在关注农村经济发展的同时越来越注重环境保护,注重资源和能源的节约,从而促进了全国农村地区绿色发展绩效的提高;从分区域来看,农村绿色发展绩效存在地区差异,绿色发展绩效较高地区是东北,年均值为2.502,西北次之,年均值为2.385,华北、华东和中南地区绩效值相对偏低;进一步地,各省、直辖市和自治区农村绿色发展绩效逐年呈现上升趋势,但有部分省市,如辽宁、河北和山西等,农村绿色发展绩效值偏低,甚至低于该省市所在地区的平均绩效值,这不仅反映了该省市农村绿色发展绩效较低,而且表明了该省市农村绿色发展绩效的高低制约着其所在地区农村整体绿色发展绩效的提升。此外,由于不同省、直辖市和自治区在资源禀赋、技术水平、政策和制度环境等方面不同,农村绿色发展的绩效值在省际之间存在较大差异。基于研究结果,在今后我国农村地区绿色发展过程中,一方面,需要加大绿色资源的投入,为农村绿色发展提供基本的条件;另一方面,需要加大对农村绿色劳动力的投入,确保为农村绿色发展提供高素质劳动力;与此同时,还要不断提高绿色技术水平,为农村绿色发展创造良好的技术条件,以此促进我国农村地区绿色绩效的进一步提高。     

多元回归和BP人工神经网络在预测混合厌氧消化产气量过程中的应用比较

对脂肪类单基质和城市污水厂剩余污泥混合厌氧消化过程的产气阶段进行基于多元回归和BP人工神经网络的产气量预测模型比较研究。实验数据分别取自反应过程的第1～16天和第17～70天。结果表明:多元回归模型的预测平均准确率分别为75.69%和79.29%;BP神经网络模型的预测平均准确率为79.05%。通过对比2种模型的预测结果可知,两种模型都有较高的预测准确率,但BP模型的预测准确率更高,更适用于混合厌氧消化产气量预测。     

Wrong-way driving crashes: A multiple correspondence approach to identify contributing factors

Objective: Wrong-way driving (WWD) crashes result in 1.34 fatalities per fatal crash, whereas for other non-WWD fatal crashes this number drops to 1.10. As such, further in-depth investigation of WWD crashes is necessary. The objective of this study is 2-fold: to identify the characteristics that best describe WWD crashes and to verify the factors associated with WWD occurrence.

Methods: We collected and analyzed 15 years of crash data from the states of Illinois and Alabama. The final data set includes 398 WWD crashes. The rarity of WWD events and the consequently small sample size of the crash database significantly influence the application of conventional log-linear models in analyzing the data, because they use maximum-likelihood estimation. To overcome this issue, in this study, we employ multiple correspondence analysis (MCA) to define the structure of the crash data set and identify the significant contributing factors to WWD crashes on freeways.

Results: The results of the present study specify various factors that characterize and influence the probability of WWD crashes and can thus lead to the development of several safety countermeasures and recommendations. According to the obtained results, factors such as driver age, driver condition, roadway surface conditions, and lighting conditions were among the most significant contributors to WWD crashes.

Conclusions: Despite many other methods that identify only the contributing factors, this method can identify possible associations between various contributing factors. This is an inherent advantage of the MCA method, which can provide a major opportunity for state departments of transportation (DOTs) to select safety countermeasures that are associated with multiple safety benefits.     

The perception of Malaysian pedestrians toward the use of footbridges

Objective: The footbridge is a vital structure in the road network and a cornerstone among crossing facilities. Yet, it suffers from low usage by pedestrians as they try to cross the street on the level. This study aims to analyze the perceptions of Malaysian pedestrians toward the use of footbridges with the consideration of different factors.

Method: The study was carried out by collecting data from field observation and questionnaire distribution on the street among the public. The data were statistically analyzed by applying multiple linear regression models and a series of chi-square tests.

Results: The study found that the most influential factor cited by pedestrians in decision making regarding using a footbridge is the existence of an escalator. Being in a hurry and the fear of heights were significantly associated with choosing not to use a footbridge. Zebra crossing was chosen as the most favorable type of crossing facility by the majority of respondents. In addition, installation of a fence and barriers was proposed as an effective procedure to prevent jaywalking. To construct new and efficient footbridges in the future, the study suggests consideration of traffic volume, posted speed limit, and the number of lanes, because these are the most influential factors to predict the usage rate.

Conclusions: The study encourages decision makers and stakeholders to consider providing escalators for new footbridges to enhance the safety of pedestrians.     

石羊河流域多情景土地利用优化及碳储量评估

研究碳储量与土地利用变化的响应关系及空间分布特征,预测未来土地利用类型变化所导致的碳储量变化趋势,可为流域政策制定、土地利用结构调整和“双碳”目标的实现提供一定的借鉴. 基于2000年、2010年和2020年三期土地利用数据,运用InVEST模型和PLUS模型,开展石羊河流域2000~2020年间和2030年自然发展、城镇发展和生态保护这3种情景下土地利用变化及其对碳储量的影响研究. 研究发现：①2000~2020年石羊河流域主要土地利用类型是耕地、草地和未利用地,且耕地、水域和建设用地的面积呈增加趋势,其中建设用地面积增幅最大. ②较2020年,2030年自然发展情景下,耕地、水域和建设用地面积均有所增加,分别增加6.15%、9.56%和29.9%;在城镇发展情景下,建设用地面积增加最多;相比其他两种情景,在生态保护情景下林地和草地面积出现了增加. ③石羊河流域2000~2020年碳储量呈平稳增加的趋势,20年间增加了0.035×10⁸ t,主要源于耕地面积的增加. ④2030年自然发展、城镇发展和生态保护3种情景下石羊河流域的碳储量分别为5.65×10⁸、5.64×10⁸和5.73×10⁸ t,较2020年均有增加,其中生态保护情景下碳储量增加最多,主要是源于草地和林地面积的增加. 研究结果表明建设用地的扩张是造成碳储量流失的主要原因,若采取有效的生态保护措施将有助提高流域碳储量,可以解决由于经济发展而导致的碳储量流失问题.