Urban Energy Efficiency from Cities in China and Policy Implications

Using 1995-2006 panel data for 210 cities, this article firstly measures total factor energy efficiency for Chinese cities with constant return to scale data envelopment analysis model,and then describes the features of regional differences. The results show that the changing trend displays four "reversed U" shapes. A turning point of widening gap occurred among cities in 2000 and there was a certain convergence among four regions. Urban energy efficiency level is unstable. Cities with low efficiency and high energy input will be the focus of energy-saving and reducing emissions. According to Tobit model, resource endowment, temperature, industrial structure, technology level and variety of policy factors should be treated differently in different situations.     

Up-regulation of contractile endothelin receptors by airborne fine particulate matter in rat mesenteric arteries via activation of MAPK pathway

Fine particle matters (PM_2.5) is a well-known risk factor for cardiovascular diseases. However, the underlying molecular mechanisms are largely unknown. Vascular hyper-reactivity plays an important roles in the pathogenesis of cardiovascular diseases. The present study was designed to investigate a hypothesis that PM_2.5 up-regulated endothelin receptors in mesenteric artery and the potential underlying mechanisms. Rat mesenteric arteries were cultured with PM_2.5. The artery contractile responses were recorded by a sensitive myograph. ET_B and ET_A receptor expressions of mRNA and protein were assessed by quantitative real-time PCR, Western blotting, and immunohistochemistry, respectively. Results showed that ET_B receptor agonist, sarafotoxin 6c induced a negligible contraction in fresh artery segments, while ET_A receptor agonist, ET-1 induced an obvious contraction. After organ culture, the contraction curve mediated by ET_B and ET_A receptors were shifted toward the left. PM_2.5 1.0 μg/ml cultured for 16 h further enhanced ET_B and ET_A receptor-mediated contractile responses with a markedly increased maximal contraction. The organ culture enhanced ET_B and ET_A receptor mRNA and protein levels from fresh arteries, which were further increased by PM_2.5. The U0126 (MEK/ERK1/2 inhibitor) and SB203580 (p38 inhibitor) significantly attenuated both organ cultured-induced and PM_2.5-induced up-regulation of ET_B receptor. U0126 also suppressed organ culture-increased and PM_2.5-increased expressions of ET_A receptor. SB203580 only suppressed PM_2.5-induced enhanced expressions of ET_A receptor In conclusion, airborne PM_2.5 up-regulates ET_B and ET_A receptors of mesenteric artery via p38 MAPK and MEK/ERK1/2 MAPK pathways.

     

Measurement of China’s green GDP and its dynamic variation based on industrial perspective

Over the previous two decades, Chinese economic development presented a rapid growth. However, with continuous industrialization and urbanization, China is confronted with great challenges of energy security and environmental issues. These problems are closely related to the current accounting method of economic growth to a certain extent. In order to meet these challenges, it is imperative to establish a green accounting system of economic growth and measure China’s green GDP and its changing trend based on the industrial perspective. Using the System of Environmental Economic Accounting (SEEA) and industry data, this paper estimates China’s green GDP and green value added by industry sectors in 2005, 2007, 2010, 2012, 2015, and 2017. The results reveal the following: First, the ratio of green GDP to traditional GDP gradually increases from 89.85 to 95.83% during 2005–2017, which means that the negative externalities of economic growth of the resource and environment are gradually weakened. Second, the difference between traditional GDP and green GDP during 2005–2017 is about 6.96%, with the carbon emissions accounting for 70.71% of environmental impact. Third, due to more than 80% of the environmental impact coming from three sectors: manufacturing (49.99%), electricity industry (22.63%), and other services (11.37%), these three sectors should be key sectors for energy conservation and emission reduction; fourth, the green GDP of the mining, electricity industries, and manufacturing accounts for the lowest proportion of GDP, which means that the development patterns of these three industries in recent years should be adjusted and optimized step by step.

     

Size dependence of in situ pH in submicron atmospheric particles in Hong Kong

Some studies have reported that small submicron atmospheric particles are more acidic than large submicron particles; other studies demonstrated a reversed trend. In this study, the size dependence of in situ pH in submicron particles in Hong Kong was investigated. The equivalent ratios of [NH₄⁺]_measured to [SO₄²⁻]_measured in submicron particles were found to be generally less than unity and size dependent, suggesting the possibility of incomplete gas–aerosol equilibrium. The Aerosol Inorganic Model-II (AIM-II) model using measured ionic compositions with the gas–aerosol partitioning disabled was used to estimate the in situ pH in different sized particles. The estimated in situ pH of different sized submicron atmospheric particles was between −2.5 and 1.5 and it generally decreases with increasing submicron particle size. At such low in situ pH, the estimated HSO₄⁻ equivalent concentrations were 3.2 times (on average) of those of H⁺ in different sized particles. The trends of the size dependence of the [NH₄⁺]_measured to [SO₄²⁻]_measured ratio and pH under different regimes of relative humidity are discussed.     

陕西靖边统万城建城时期地表物质成因与自然环境

为查明距今约1600年的统万城建城时期的自然环境和该古城是否建在风沙沉积之上这一长期争议的问题,对6个钻孔剖面样品进行粒度和X-射线衍射等分析。结果表明：城墙内外地表之下均为湖泊沉积,沉积物特点与风沙沉积物显著不同,主要表现为以下五个方面：（1）沙层含有褐黄色针铁矿;（2）有多个深灰色沉积层;（3）沙层中粗砂含量显著大于风积沙层;（4）沙层中粒度成分的分选性比风积沙层明显差;（5）细粒斑点中Fe₂O₃与Al₂O₃含量比风沙沉积物高。本文获得的证据充分表明,在统万城建城前后,该区自然环境较好,普遍分布的是由湖积物组成的高平地,统万城建在湖积沙层之上。统万城建城时期基本没有发生沙漠化,沙漠化发生在建城之后的一定时期。     

陕西省城镇污泥养分与重金属含量特征分析

分不同水期调查研究了陕西省不同地区32家城镇污水处理厂出厂污泥中总氮、总磷、总钾、有机质以及Cr、Cu、Ni、Pb、Zn、As 6种重金属元素的含量特征。结果表明:1)陕西省城镇污泥中氮、磷养分及有机物含量较为丰富,但总钾含量不高;污泥总养分含量大体呈现枯水期>平水期>丰水期的分布特征,其中总氮与有机物含量受水期的影响极显著(P_J-T<0.001),而总磷和总钾含量受水期的影响并不显著(P_J-T>0.05)。2)陕西省城镇污泥中重金属含量呈对数正态分布,6种重金属元素含量顺序为Zn>Cu>Cr>Pb>Ni>As;不同水期污泥重金属含量不存在显著性差异(P_ANOVA>0.05)。3)总体而言,陕西省城镇污泥具有较高的农用价值,且重金属含量处于相对较低的水平,较适合施用于林地、牧草地和不种植食用农作物的耕地,以及用于中碱性土质的土地改良,同时需特别注意,As含量必须控制在标准限值以内。     

宝鸡市冬季一次持续性重污染过程特征分析

污染气象成因和污染物区域传输作用对本地污染影响较大,研究不同地区污染气象成因和污染物区域传输作用对本地污染的治理有重要意义.利用污染物浓度监测和气象要素观测资料,采用统计学分析方法、特征雷达图和HYSPLIT-4后向轨迹模型分析宝鸡市2018年12月29日—2019年1月8日一次持续性重污染过程的气象成因和污染特征.结果表明:①此次重度污染持续时间长、强度大,污染过程中有6 d空气质量指数(AQI)达到重度及以上污染(AQI>200),ρ(PM_2.5)平均值达205.4 μg/m3,有2 d达到严重污染(AQI>300).②气象条件对污染物浓度的影响显著,高低空环流形势形成稳定层结,容易造成污染物累积.东南大风将污染气团远距离输送到宝鸡市,西北静小风使得污染物在本地聚集加重污染.③重污染维持阶段,ρ(PM_2.5)/ρ(PM₁₀)在0.9左右,说明此次污染过程PM_2.5占比较大,污染物的二次转化作用明显;ρ(NO₂)/ρ(SO₂)为6.2,表征移动源贡献率高于固定源;ρ(CO)/ρ(SO₂)呈先增后减的变化特征,表明静稳天气持续,本地源排放对重污染的贡献逐渐凸显.④特征雷达图结果表明,此次重污染过程的污染类型由发展阶段的污染特征不明显和燃煤型污染特征,逐渐转化为偏二次污染类型,重污染过程结束后污染类型以偏扬尘型为主.研究显示,气象条件和传输扩散对宝鸡市重污染影响显著,宝鸡市重污染应急需优先管控移动源,汾渭平原应加强区域联动,共同治理环境污染问题.      

考虑不同场景的砖木结构古建筑火灾特征研究

为探明砖木结构古建筑火场下的特征,定量分析不同火灾场景下,建筑内部温度、烟气浓度等参数的变化。选取中国北方典型的砖木结构体系的四合院韩城党家村贾祖祠为研究对象,采用PyroSim建模分析,研究不同火灾场景下不同时间点的温度、CO浓度、能见度等变化。研究结果表明:贾祖祠主厢房较封闭,火灾中火源周围温度峰值可达750 ℃,CO质量浓度达到0.003 kg/m3,能见度几乎为0 m,风速最高为10 m/s且极不稳定;四合院中主厢房空间布局高,火灾中这些参数的影响会导致严重的轰燃现象发生,故此处发生火灾更易产生严重危害。对不同场景的砖木结构古建筑重要火灾因素发展规律的研究,能为古建筑的性能化防火提供科学参考依据。