Analysis of 3-year observations of CFC-11, CFC-12 and CFC-113 from a semi-rural site in China

In-situ measurements of atmospheric chlorofluorocarbons (CFCs) can be used to the assess their global and regional emissions and to check for compliance with phase-out schedules under Montreal protocol and its amendments. The atmospheric mixing ratios of CFC-11 (CCl₃F), CFC-12 (CCl₂F₂) and CFC-113 (CCl₂F–CClF₂) have been measured by an automated in-situ GC-ECDs system at the regional Chinese Global Atmosphere Watch (GAW) station Shangdianzi (SDZ), from November 2006 to October 2009. The time series for these three principal CFCs showed large episodic events and background conditions occurred for approximately 30% (CFC-11), 52% (CFC-12) and 56% (CFC-113) of the measurements. The mean background mixing ratios for CFC-11, CFC-12 and CFC-113 were 244.8 ppt (parts per trillion, 10^?12, molar) 539.6 ppt and 76.8 ppt, respectively, for 2006–2009. The enhanced CFC mixing ratios compared to AGAGE sites such as Trinidad Head (THD), US and Mace Head (MHD), Ireland suggest regional influences even during background conditions at SDZ, which is much closer to highly-populated areas. Between 2006 and 2009 background CFCs exhibited downward trends at rates of ?2.0 ppt yr^?1 for CFC-11, ?2.5 ppt yr^?1 for CFC-12 and ?0.7 ppt yr^?1 for CFC-113. De-trended 3-year average background seasonal cycles displayed small fluctuations with peak-to-trough amplitudes of 1.0 ± 0.02 ppt (0.4%) for background CFC-11, 1.3 ± 2.1 ppt (0.3%) for CFC-12 and 0.2 ± 0.4 ppt (0.3%) for CFC-113. On the other hand, during pollution periods these CFCs showed much larger seasonal cycles of 11.2 ± 10.7 ppt (5%) for CFC-11, 7.5 ± 6.5 ppt (2%) for CFC-12 and 1.0 ± 1.2 ppt (1.2%) for CFC-113, with apparent winter minima and early summer maxima. This enhancement was attributed to prevailing wind directions from urban regions in summer and to enhanced anthropogenic sources during the warm season. In general, horizontal winds from northeast showed negative contribution to atmospheric CFCs loading, whereas South Western advection (urban sector: Beijing) had positive contributions.     

垃圾炉一次风量对炉床燃烧影响的仿真研究

针对垃圾焚烧炉床层内垃圾燃烧过程复杂性及影响垃圾燃烧效率因素多的问题,运用数值仿真方法对某垃圾焚烧炉床层垃圾燃烧进行了模拟,获得了垃圾质量流失速率、水分蒸发速率、挥发分释放速率、焦炭燃烧速率和烟气的温度;并在50~1 000 Nm3/min范围内改变一次风流量,获得了床层质量流失比值、过剩空气系数和烟气中各组分的质量百分比含量。仿真结果显示,一次风流量取值517.47~6`32.09 Nm3/min时燃烧效率较高;炉排两端区域的一次风流量在50~75 Nm3/min时,可以使垃圾床表面平均温度明显提高,而且还可以提高燃烧效率,同时减少供风总量,节约能源与动力资源。本研究对优化设计垃圾焚烧炉,提高床层内垃圾的燃烧效率有一定参考价值。     

污泥含炭吸附剂对挥发性有机废气吸附实验研究

研究了污泥含炭吸附剂对挥发性有机污染物的吸附特性。结果表明,污泥含炭吸附剂对苯系物的吸附为典型的物理吸附,其吸附甲苯等温线的类型系优惠型吸附等温线,表明具有良好的吸附能力;在吸附反应温度为20℃,气体流量为500 mL/m in(停留时间为0.424 s),甲苯浓度为2 700 mg/m3时,甲苯的饱和吸附容量为150.0 mg/g;同时,研究表明污泥含炭吸附剂对苯系物的饱和吸附容量和吸附强弱次序为二甲苯甲苯苯。结果表明污泥含炭吸附剂适合对中低浓度有机废气的吸附净化。     

光/电Fenton牺牲阳极法降解有机污染物

采用Fe片为阳极和石墨为阴极,在可见光(λ450 nm)照射并外加电压条件下,以有机染料橙Ⅱ(orangeⅡ)及有机无色小分子2,4-二氯苯酚(2,4-dichlorophenol,DCP)为目标化合物,探讨了光/电Fenton牺牲阳极法降解有机污染物的最佳反应条件,结果表明,在电压=3 V,pH=3.0,H2O2浓度为5×10-5mol/L时,orangeⅡ的降解效果最好,反应10 h矿化率可达到78%,210 min内2,4-DCP降解率为91.4%。通过对光/电Fenton体系原位循环伏安参数测定及过氧化物酶催化反应吸光光度法和苯甲酸荧光分析法检测光/电Fenton降解orange II过程中H2O2和羟基自由基(.OH)的变化,表明orangeⅡ降解过程涉及.OH历程。     

酸雨对建筑材料的影响及防治研究综述

综合分析了酸雨对建筑外墙的涂料、石材、混凝土等主要建筑构件的腐蚀原理,并提出了防治措施,来预防酸雨对建筑材料的侵害。     

丹江口库区坡耕地柑桔园不同覆盖方式下地表径流氮磷流失特征

以坡耕地柑桔园为研究对象,地表覆盖方式采用对照、秸秆覆盖和地膜覆盖3个处理,实验采用完全方案。结果表明,在本实验条件下,坡地地膜覆盖处理一定程度增加了径流量,而秸秆覆盖处理与对照每次降雨径流量基本相当;各处理土壤氮磷养分均有一定程度的流失,以氮素流失量较高,磷素流失量相对较低;在地膜覆盖条件下,柑桔园地表径流中N、P流失量较高,其总氮和总磷流失系数分别达0054%和0064%,而秸秆覆盖总氮和总磷流失系数最低;对不同地表覆盖方式柑桔园地表径流水体氮素形态特征分析表明,可溶性氮素占总氮的比例较高,可溶性氮素中又以NO-3 N为主,而NH+4 N所占的比重较低。以上结果说明,在丹江口库区,氮素污染风险要高于磷,防控的主要矛盾是氮,而秸秆覆盖是减少坡耕地养分流失较好的管理措施     

Managing the Three-Rivers Headwater Region, China: From Ecological Engineering to Social Engineering

The three-rivers headwater region (THRHR) of Qinghai province, China plays a key role as source of fresh water and ecosystem services for central and eastern China. Global warming and human activities in the THRHR have threatened the ecosystem since the 1980s. Therefore, the Chinese government has included managing of the THRHR in the national strategy since 2003. The State Integrated Test and Demonstration Region of the THRHR highlights the connection with social engineering (focus on improving people’s livelihood and well-being) in managing nature reserves. Based on this program, this perspective attempts a holistic analysis of the strategic role of the THRHR, requirements for change, indices of change, and approaches to change. Long-term success of managing nature reserves requires effective combination of ecological conservation, economic development, and social progress. Thus, the philosophy of social engineering should be employed as a strategy to manage the THRHR.     

Hexabromocyclododecanes in limnic and marine organisms and terrestrial plants from Tianjin,China: Diastereomer- and enantiomer-specific profiles,biomagnification, and human exposure

To interpret the distribution of hexabromocyclododecanes (HBCDs) in various organisms, we measured the concentrations and diastereomer and enantiomer profiles of HBCDs in 21 different species of limnic and marine cohorts from Tianjin, China. The concentration ranges of HBCDs in limnic and marine organisms were 64.3–1111 ng g⁻¹ lw and 85.5–989 ng g⁻¹ lw, respectively. Living habitat and feeding habits had important impacts on HBCD diastereomer distribution. Most of the species appeared to preferentially select (+)-α-, (−)-β- and (−)-γ-HBCD. There is a tendency that the total and α-HBCDs were magnified as trophic level increased with trophic magnification factors (TMFs) around 2. The concentrations of HBCDs in the limnic and marine fishes were highest in the liver, followed by the gill, skin, and muscle. In terrestrial plants, the highest concentrations of HBCDs were observed in the leaf, followed by the root and the rhizosphere soil. Plants showed enantioselectivity for HBCD enantiomers, which varied with plant species and organs (leaf vs. root) of the same plant. Higher estimated daily intakes (EDIs) of HBCDs were observed from fish than from wheat.     

Kinetics and mechanism for omethoate degradation by catalytic ozonation with Fe(III)-loaded activated carbon in water

The kinetics and mechanism for degradation of omethoate (OMT) by catalytic ozonation with Fe(III)-loaded activated carbon (Fe@AC) were investigated in this study with focus on identification of degradation byproducts. The rate constants of OMT reacting with ozone and hydroxyl radical (OH) were determined to be 0.04 and 5.3 × 10⁸ M^?1 s^?1 at pH 7.5 and 20 °C, respectively. OMT was predominantly degraded by OH in the catalytic ozonation with Fe@AC. The high-molecular-weight degradation byproducts identified were O,O,O-trimethyl phosphoric ester (TMP), pyrrolidin-2-one, N-methyl-2-sulfanylacetamide, 2-(methylthio)acetamide, O,O,S-trimethylthiophosphate (STMP), and N-methyl-2-(methylthio)acetamide. Besides, low-molecular-weight organic acids and inorganic anions were also detected and quantified, including formic, acetic and oxalic acids as well as nitrate, sulfate and phosphate ions. In the catalytic ozonation, TMP and phosphate were two major P-containing byproducts resulting from OMT degradation. The toxicity of OMT solution gradually decreased during the catalytic ozonation, indicating that Fe@AC is a safe catalyst for OMT removal by ozone in water.     

Air–water exchange fluxes of polycyclic aromatic hydrocarbons in the tropical coast,Taiwan

Air–water exchange fluxes of polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured in air and water samples from two sites on the Kenting coast, located at the southern tip of Taiwan, from January to December 2010. There was no significant difference in the total PAH (t-PAH) concentrations in both gas and dissolved phases between these two sites due to the less local input which also coincided to the low levels of t-PAH concentration; the gas and dissolved phases averaged 1.29 ± 0.59 ng m^?3 and 2.17 ± 1.19 ng L^?1 respectively. The direction and magnitude of the daily flux of PAHs were significantly influenced by wind speed and dissolved PAH concentrations. Individual PAH flux ranged from 627 ng m^?2 d^?1 volatilization of phenanthrene during the rainy season with storm–water discharges raising dissolved phase concentration, to 67 ng m^?2 d^?1 absorption of fluoranthene during high wind speed periods. Due to PAH annual fluxes through air–water exchange, Kenting seawater is a source of low molecular weight PAHs and a reservoir of high molecular weight PAHs. Estimated annual volatilization fluxes ranged from 7.3 μg m^?2 yr^?1 for pyrene to 50 μg m^?2 yr^?1 for phenanthrene and the absorption fluxes ranged from ?2.6 μg m^?2 yr^?1 for chrysene to ?3.5 μg m^?2 yr^?1 for fluoranthene.