液氮冻融破碎生物污泥制备生物絮凝剂

利用城市剩余生物污泥,采用液氮冻融破碎、提取液提取的方法制备了生物污泥絮凝剂。对絮凝剂的制备条件及其絮凝性能进行了研究,结果表明:采用液氮冻融破碎,pH为1.0的稀盐酸溶液作为提取液提取所制备的絮凝剂,对高岭土悬浮液的絮凝效率可达98.5%。液氮冻融破碎的次数对絮凝剂制备没有明显影响。同时考察了絮凝剂投加量以及絮凝体系的pH对絮凝剂絮凝活性的影响。     

基于动态遥感数据的北京主城区环带间植被覆盖变化

20世纪80年代以来,北京市进入高速城市化进程,主城区(六环内)植被覆盖发生了巨大变化。分别利用1984年、1995年、2004年和2014年的8—9月北京六环内的Landsat遥感数据,对其进行辐射定标、大气校正和拼接裁剪,以计算归一化植被指数(NDVI),获取3个10年间和各环带植被覆盖面积及覆盖度的变化。结果显示:六环内植被覆盖度由1984年的76.80%(1 742.44 km ²)降至2014年的48.73%(1 105.61 km ²)。虽然2014年与1984年相比二环内和二环至三环植被覆盖度分别增加8.43和4.33个百分点,但三环至四环、四环至五环、五环至六环植被覆盖度降幅逐渐增大,降幅分别为12.23、27.62、32.97个百分点。建议通过空间规划手段为不同环带间以植被覆盖为代表的城市生态系统建设提供差异化思路:如三环内应结合城市精细化治理为核心区留白增绿,见缝插绿;三环至五环间随着城市建设趋于稳定,为中型城市生态空间的增建带来机遇;五环至六环间可结合百万亩造林,增加都市农田等方式,建设多种类大型城市绿色空间,进而综合提升北京主城区城市生态系统服务功能。     

稠油火驱开采技术节能减排效果分析

火驱作为稠油热采的有效接替技术,与注蒸汽开采技术相比,具有采收率高,能耗低,CO_2排放少的优势。文章从火驱驱油机理特征阐述了火驱与注蒸汽技术的不同点,从燃料开采能耗、热效率、注入剂资源、数据对比四个方面分析火驱比注蒸汽热效率高,无燃料开采成本,能耗是注蒸汽的50%;从CO_2气体排放方式和排放量对比可知,火驱能够减少温室气体排放,为油田节能减排、环保生产起到积极作用。     

Is there an inverted U-shaped curve? Empirical analysis of the Environmental Kuznets Curve in agrochemicals

As the largest contributor to water impairment, agriculture-related pollution has attracted the attention of scientists as well as policy makers, and quantitative information is being sought to focus and advance the policy debate. This study applies the panel unit root, heterogeneous panel cointegration, and panel-based dynamic ordinary least squares to investigate the Environmental Kuznets Curve on environmental issues resulting from use of agricultural synthetic fertilizer, pesticide, and film for 31 provincial economies in mainland China from 1989 to 2009. The empirical results indicate a positive long-run co-integrated relationship between the environmental index and real GDP per capita. This relationship takes on the inverted U-shaped Environmental Kuznets Curve, and the value of the turning point is approximately 10,000–13,000, 85,000–89,000 and over 160,000 CNY, for synthetic fertilizer nitrogen indicator, fertilizer phosphorus indicator and pesticide indicator, respectively. At present, China is subject to tremendous environmental pressure and should assign more importance to special agriculture-related environmental issues.     

HCHs and DDTs in Yellow River of Henan section—a typical agricultural area in China: levels,distributions and risks

The levels, potential sources and ecological risks of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in Yellow River of Henan section, a typical agricultural area in China, were investigated. Surface water samples and suspended particulate matters (SPMs) were collected from 23 sites during two seasons. In wet season, the residues of ∑HCHs (α-HCH, β-HCH, γ-HCH and δ-HCH) and ∑DDTs (p,p′-DDT, o,p′-DDT, p,p′-DDE, p,p′-DDD) ranged from 41.7 to 290 and 4.42 to 269 ng/L in surface water, while those varied from 0.86 to 157 and 1.79 to 96.1 ng/g dw in SPM, respectively. Moreover, in surface water, the levels of HCHs and DDTs in wet season were much higher than those in dry season. The reverse was true for residues of HCHs and DDTs in SPM. Compared with the large rivers in other regions, the levels of HCHs and DDTs in the studied area ranked at high levels and the residual concentrations might cause adverse biological risk, especially for ∑HCHs during wet season. Distributions of HCHs and DDTs delineated that the input of tributaries made a significant effect on the residue of HCHs and DDTs in the mainstream. ∑HCHs in surface water were consist of 26.7 % α-HCH, 30.0 % β-HCH, 37.9 % γ-HCH and 5.45 % δ-HCH and those in SPM contained 5.16 % α-HCH, 22.1 % β-HCH, 60.5 % γ-HCH and 12.2 % δ-HCH on average. Combined with ratios of α-HCH/γ-HCH in surface water (0.70) and in SPM (0.09), the results strongly indicated that lindane was recently used or discharged in the studied area. The mean percentage of DDTs′ isomers were 28.7 % p,p′-DDT, 29.8 % o,p′-DDT, 28.1 % p,p′-DDE and 13.4 % p,p′-DDD in surface water, while those were 12.5 % p,p′-DDT, 31.8 % o,p′-DDT, 30.5 % p,p′-DDE and 25.1 % p,p′-DDD in SPM. The ratios of (DDE + DDD)/∑DDTs and o,p′-DDT/p,p′-DDT revealed that the DDTs in the studied area mainly derived from long-term weathering of technical DDTs residue and the input of dicofol.     

丙烯酰胺对斑马鱼各器官的毒性作用及生殖细胞的DNA损伤

在我国,聚丙烯酰胺(PAM)主要应用于石油开采,其长期暴露于环境中可以降解成有毒的丙烯酰胺(AM)。为探究在降解过程中AM的毒性作用,选择斑马鱼作为受试动物,进行AM长期毒性暴露40 d,考察了对斑马鱼的肝脏、脑组织、心脏、腮等器官的影响情况。结果表明:在2.04 mg·L~(-1)、6.12 mg·L~(-1)和18.36 mg·L~(-1)暴露浓度下,形态学观察斑马鱼的鳃丝,鳃小片和鳃细胞有严重的受损现象;随着浓度的升高斑马鱼肝脏、脑组织和心脏中MDA含量、LDH活力的升高,SDH和Na+-K+-ATPase活力的降低,均对其肝脏、脑组织和心脏造成氧化损伤作用,从而影响了斑马鱼体内细胞能量代谢过程。采用彗星试验检测斑马鱼的生殖腺细胞DNA损伤,结果显示暴露于浓度为2.04 mg·L~(-1)~18.36 mg·L~(-1)的AM后,斑马鱼的DNA损伤均表现为显著差异(P0.01)。上述研究结果均确定了AM对斑马鱼的毒性效应并可造成其生殖腺细胞的DNA损伤。     

基于WoS文献计量分析PM2.5研究现状

运用文献计量学的研究方法,以Web of Science(WoS)为数据源,利用Excel软件对1990—2015年发表的相关PM_(2.5)研究的文献进行数据统计与分析,从文献发表年代、主要发文国家/地区、研究机构、期刊分布、热点文献等方面采用定量、定性的方法揭示了目前世界PM_(2.5)的研究进展。结果表明,近10年关于PM_(2.5)研究发文量增长较快,PM_(2.5)研究全球关注度较高,美国无论发文量、总被引频次和H指数都远超过其他国家/地区,体现了美国在PM_(2.5)研究领域的主导地位;PM_(2.5)相关领域的研究机构主要集中在美国和中国(未包含港、澳、台地区数据);文献多发表在相关大气化学与物理学、环境、健康、气溶胶等领域的刊物上;当前研究热点由PM_(2.5)所引发全球关注的生态环境问题转入对人体健康的影响上,且国际合作研究成为发展趋势。中国自2006年以来PM_(2.5)的研究文献增速显著,发文量和累计被引频次位居世界第二,仅低于美国。     

大连市臭氧污染特征及典型污染日成因

通过对大连市区10个空气监测子站的监测数据进行分析,探讨了大连市臭氧污染的时空分布、气象条件对臭氧污染的影响,对臭氧污染日进行了归类分析。结果表明,大连市臭氧污染主要出现在4—10月。在强紫外辐射、高温、低湿、低压和低风速的气象条件下,监测点位的臭氧浓度较高。臭氧污染日的日变化分为单峰型、双峰型和夜间持续升高型3种类型。通过对2015年的一次高浓度臭氧污染过程的气象条件、污染物浓度和污染气团轨迹进行分析,发现臭氧浓度在夜间持续升高现象与区域输送密切相关。     

中国大气超级站发展与展望：基于问卷调研的统计研究

大气环境综合观测研究站(简称大气超级站)是开展大气环境污染综合立体观测、进行大气重污染过程污染特征动态表征、深入分析大气污染成因的重要平台。了解中国当前不同地区大气超级站的建设和应用现状、存在的问题及发展需求,有利于科学指导和规范中国大气超级站的设计、建设、运维和应用,提高其在大气重污染过程应急管控和空气质量改善中的技术支撑能力。研究通过对国内60余个大气超级站进行问卷调研,综述了中国目前大气超级站的现状,并基于统计分析结果,对中国大气超级站发展提出建议。