贵州坝子土地利用显性和隐性转型实证研究

土地利用转型研究是当前研究热点,坝子是以高原山地为主的贵州省人类活动最为显著的区域,探讨贵州省坝子以耕地为主的土地利用转型与功能演变两者之间的相互作用关系具有重要意义。以1966～2016年的高分辨率遥感影像为主要数据源,结合实地调查,建立坝子土地利用功能分类体系,以贵州典型坝子涟江坝子为例,进行了坝子土地利用显性和隐性转型实证研究。结果表明:从1966～2016年,坝子经历了土地利用的显性转型和隐性转型,耕地转型与功能演变相互协同耦合变化阶段特征明显,其实质是坝子社会经济发展阶段转型下资源配置方式的转变主导而成。案例研究表明贵州坝子土地利用转型总体可分为粗放式阶段、粗放式向集约化过渡阶段、逐步集约化阶段和集约化增强阶段。"个体、政府和市场"3个层面和"文化、制度、社会经济、人口技术区位"4个重要因素是坝子土地利用转型的驱动控制系统。     

Understanding of regional air pollution over China using CMAQ,part I performance evaluation and seasonal variation

The U.S. EPA Models-3 Community Multiscale Air Quality (CMAQ) modeling system with the process analysis tool is applied to China to study the seasonal variations and formation mechanisms of major air pollutants. Simulations show distinct seasonal variations, with higher surface concentrations of sulfur dioxide (SO₂), nitrogen dioxide (NO₂), and particulate matter with aerodynamic diameter less than or equal to 10 μm (PM₁₀), column mass of carbon monoxide (CO) and NO₂, and aerosol optical depth (AOD) in winter and fall than other seasons, and higher 1-h O₃ and troposphere ozone residual (TOR) in spring and summer than other seasons. Higher concentrations of most species occur over the eastern China, where the air pollutant emissions are the highest in China. Compared with surface observations, the simulated SO₂, NO₂, and PM₁₀ concentrations are underpredicted throughout the year with NMBs of up to ?51.8%, ?32.0%, and ?54.2%, respectively. Such large discrepancies can be attributed to the uncertainties in emissions, simulated meteorology, and deviation of observations based on air pollution index. Max. 1-h O₃ concentrations in Jan. and Jul. at 36-km are overpredicted with NMBs of 12.0% and 19.3% and agree well in Apr. and Oct. Simulated column variables can capture the high concentrations over the eastern China and low values in the central and western China. Underpredictions occur over the northeastern China for column CO in Apr., TOR in Jul., and AODs in both Apr. and Jul.; and overpredictions occur over the eastern China for column CO in Oct., NO₂ in Jan. and Oct., and AODs in Jan. and Oct. The simulations at 12-km show a finer structure in simulated concentrations than that at 36-km over higher polluted areas, but do not always give better performance than 36-km. Surface concentrations are more sensitive to grid resolution than column variables except for column NO₂, with higher sensitivity over mountain and coastal areas than other regions.     

微电解联合物化法处理维生素B12难降解废水的研究

对使用微电解联合物化法处理维生素B12难降解废水进行了分析。通过实验研究了微电解联合物化法处理维生素B12废水的最佳工艺条件。在最佳工艺条件下,维生素B12废水色度去除达88.46%,COD去除率达到71.06%。该处理方法最后将污染物质直接吸附于改性膨润土上,不产生浓缩废水、酸碱废水等更加难以处理的废水,并且不带入有毒有害物质,可以有效降低水中污染物含量,减少后续生物处理设备的污染负荷。     

Biohydrogen production from dairy manures with acidification pretreatment by anaerobic fermentation

Background, aim, and scope  

Hydrogen is a clean and efficient energy source and has been deemed as one of the most promising carriers of new energy for the future. From an engineering point of view, producing hydrogen by mixed cultures is generally preferred because of lower cost, ease of control, and the possible use of organic waste as feedstock. The biological hydrogen production has been intensively studied in recent decades. So far, most investigates of biohydrogen production are still confined to using pure carbohydrates and carbohydrate-rich wastewater. Nowadays, the large amounts of livestock manure, which come from cattle feedlots, poultry, and swine buildings, are causing a major environmental issue because it has become a primary source of odors, gases, dust, and groundwater contamination. The increasingly stringent requirements for pollution control on livestock manures are challenging the scientific community to develop new waste treatment strategies. Thus, there is a pressing need to develop nonpolluting and renewable energy source utilizing the organic waste (e.g., livestock manure). It is well known that anaerobic digestion had successfully been used for the disposal of manures to produce methane in the last two decades. Recently, an alternative strategy has been developed to convert livestock manures (e.g., dairy manures) to biohydrogen as a high value-added clean energy source instead of methane. However, little information is available on hydrogen production from dairy manure via the mixed anaerobic microbe. As far as we know, the hydrogen production is habitually accompanied with production of volatile fatty acids (VFAs), such as acetate, butyrate, and propionate, which are also an optimal feedstock for production of methane by anaerobic digestion. Provided that the biohydrogen production from dairy manure is further combined with the anaerobic digestion of the effluent from the producing hydrogen reactor that would be a one-stone two-bird paradigm, it not only produces a clean and readily usable biologic energy but also cleans up simultaneously the environment in a sustainable fashion.     

Fate and transport of engineered nanomaterials in the environment

With the fast development of nanotechnology, engineered nanomaterials (ENMs) will inevitably be introduced into the various environment. Increasing studies showed the toxiccity of various ENMs, which raises concerns over their fate and transport in the environment. This review focuses on advances in the research on environmental transport and fate of ENMs. Aggregation and suspension behaviors of ENMs determining their fate and transport in aqueous environment are discussed, with emphasis on the influencing factors, including natural colloids, natural organic matter, pH, and ionic strength. Studies on the transport of ENMs in porous media and its influencing factors are reviewed, and transformation and organismcleansing, as two fate routes of ENMs in the environment, are addressed. Future research directions and outlook in the environmental transport and fate of ENMs are also presented.     

我国实施循环经济的制度初探

循环经济是在资源与环境约束下追求有效经济增长的一种新的经济发展模式。循环经济本质上是一种生态经济,以资源利用的生态性、技术基础的复杂性、经济运行的社会性等为根本特征。制度与循环经济相互依存、相互制约,发展循环经济离不开制度的规范和引导。论述了我国当前在市场经济条件下发展循环经济中遇到的制度障碍,如市场机制障碍、产权制度障碍和政策法规障碍等,并提出解决循环经济发展的制度障碍需要建立一个完整的、相互补充的制度体系。     

城市污泥干燥焚烧一体化处理工艺的研究

城市污泥的产量日益增加,若不进行处理,不仅浪费土地资源而且污染环境。对污泥中的水分形式和污泥的处理工艺进行了分析,认为污泥的干燥和焚烧是最完全、稳定的处理工艺。提出一种城市污泥干燥焚烧一体化处理工艺,利用污泥自身焚烧产生的热值,提供干燥系统所需的热量,达到整个污泥处理系统能量的基本自给。对该系统的流程和各工艺进行了分析,结果表明该系统的污泥减量大、干燥效率高、运行成本低、尾气排放有效控制。     

Levels,congener profile and inventory of polychlorinated biphenyls in sediment from the Songhua River in the vicinity of cement plant,China: a case study

This study investigated the contamination levels, homologue, and congener profiles and evaluated the residue inventory of polychlorinated biphenyls (PCBs) in sediment of the Songhua River in the vicinity of cement plant. The total concentration of detected 35 PCB congeners ranged from 1.12 to 2.19 ng/g dry weight (dw) in sediment, with a mean value of 1.56 ng/g dw, and the concentration of PCBs decreased in the following order: the downstream?>?cement plant?>?upstream. The results of total organic carbon (TOC)-normalized PCB concentrations indicate that the sediments have low potential ecological risk in this area. The study results on homologue and congener of PCBs show that the emissions from cement production could be the major sources of PCBs in sediment, and the low-chlorinated PCBs will be exchanged among air, water, and sediment with increasing temperature during summer and flow to downstream with water during the wet season. The spatial density and total burden of PCBs in the surface sediments were 17.2 ng/cm² and 1.2 kg, respectively. To our knowledge, this study is the first to explore the pollution characteristics of unintentionally produced PCB emissions from cement industry by means of monitoring sediment samples.     

利用多年期赤泥和煤矸石制备烧结砖

以多年期赤泥和煤矸石为主要原料,分析了其化学成分和物性特征,通过设计不同的原料配比和烧结温度,探讨其最佳工艺条件以及各种参数指标,试图为赤泥的大宗化利用提供一种新的途径。实验结果表明最佳工艺条件为:多年期赤泥与煤矸石质量比为20∶80,成型压力为6 MPa,烧结温度为1 100℃左右保温2 h。烧结砖体"泛霜"现象基本消失,抗压强度为12.18 MPa、吸水率为21.6%,满足国家粉煤灰普通烧结砖GB5101-2003中的要求。     

珠海市社会经济发展与资源环境的协调度分析

经济与资源环境协调发展成为研究热点,众多学者运用不同的数学方法对区域经济和环境的协调度进行了分析。目前这方面的研究仅包括经济和环境两大系统,未将社会发展作为独立的系统,且指标的选取未能体现区域经济发展的特点。根据珠海市的实际,对原有的协调度计算方法进行适当调整,得出珠海市社会经济发展与资源环境协调度发展的状况属于良好协调发展类中的经济滞后型。