温带季节性分层水库浮游植物功能类群的时空演替

为探究我国北方温带季节性分层水库浮游植物群落结构的时空演替特性,于2014年7月~2015年6月对山东枣庄市水源水库周村水库进行每月2次的分层采样分析,采用Renolyds和Padisák等提出的功能类群划分方法对水库浮游植物群落进行分类,并结合水库水文、水质,分析优势功能类群时空演替规律及其主要环境影响因子.结果表明:周村水库共检出浮游植物112种,隶属于7门63属,可划分为18个功能群类.周村水库浮游植物功能类群演替具有明显的季节性分布特性:其中夏秋季热分层期主要以鞘丝藻(Lyngbya sp.)、螺旋藻属(Spirulina sp.)等丝状蓝藻为代表的S₁功能类群占优势,而冬季混合期以梅尼小环藻(Cyclotella meneghiniana)、针杆藻(Synedra sp.)等能适应低温、弱光的C+D功能类群为优势群落;浮游植物功能类群分布在垂向上并无较大差异.冗余分析(RDA)显示:热分层、降雨量和水温是影响浮游植物功能类群时空演替的主要环境因子.     

基于LUCC的艾比湖区域生态风险评价及预测研究

以新疆内陆艾比湖流域典型区域为研究区,基于RS和GIS技术分析1998、2013年土地利用变化,尝试用CA-Markov模型预测2028年土地利用/覆盖变化.借助Fragstats3.4软件,基于土地利用/覆盖变化构建景观生态风险评价模型,分析1998~2028年景观生态风险的时空分异特征.结果表明：（1）1998~2013年,研究区土地类型面积变化明显.耕地面积增加量最大,增加的面积为152139hm²,而未利用地面积减少量最大,减少的面积为67605hm².2013~2028年,耕地和裸露的河床及盐渍地的面积增加明显,增加的面积分别为30730hm²,12427hm²,而未利用地和水体的面积分别从954376hm²和44889hm²,减至921079hm²和37157hm².（2）1998~2028年,研究区生态风险等级空间分布差异明显.高生态风险区面积变化较为显著,其面积分别约占总面积的36.6%,7.3%,23.7%.1998~2028年,全局Moran's Ⅰ值分别为0.436962,0.442202,0.506622,表现为一定程度的正相关.（3）1998~2028年,耕地分布在低,较低生态风险的比重上升,所占百分比分别为58.46%,78.58%,79.9%.林、草地类型的各生态风险等级的所占的比重的波动较大.     

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.     

彗星电泳法测定双酚A对雄性幼龄小鼠脑细胞的DNA损伤

双酚A是一种日常生活中无处不在的环境雌激素,具有生殖和神经毒性,但低剂量长期暴露对发育期青少年的危害性常常被低估或忽视。本研究以4周龄雄性清洁级小鼠为实验对象,以茶油作为溶媒对照,分别以双酚A浓度为0μg·m L-1、0.1μg·m L-1、10μg·m L-1和1 000μg·m L-1的茶油灌胃小鼠8周,然后利用彗星电泳法检测各组小鼠脑细胞的DNA损伤。结果显示,不同浓度双酚A暴露8周后,彗星电泳图像显示小鼠脑细胞DNA出现不同程度的损伤,随着暴露剂量的增加,带有彗尾的脑细胞比率从对照组小鼠的9.5%分别升高到暴露组小鼠的34.5%、36.0%和50.5%,细胞总体的尾部DNA含量、尾长和尾矩也都逐渐增加,而且各双酚A暴露组小鼠与溶媒对照组小鼠脑细胞都具有显著性差异(P0.01),这说明中长期双酚A暴露(包括低浓度环境暴露)会导致雄性幼龄小鼠脑细胞的DNA损伤。     

左氧氟沙星在蒙脱石存在条件下对大肠杆菌的毒性效应

采用批实验研究了蒙脱石对左氧氟沙星的吸附机理及对左氧氟沙星抗菌作用的影响。结果表明,中性条件下存在培养基时,左氧氟沙星在蒙脱石上前2 h即达到吸附平衡,吸附等温线符合Langmuir吸附方程,吸附率达90%以上;蒙脱石吸附左氧氟沙星存在阳离子交换作用、氢键作用、疏水作用、阳离子键桥作用、静电吸附作用等物理化学过程;蒙脱石本身不具有抑菌、杀菌活性,且由于蒙脱石增大了微生物附着的比表面积,在特定情况下可以促进微生物的生长;扣除其对微生物生长的促进作用后,蒙脱石吸附左氧氟沙星降低了后者的毒性效应,其抑菌率降低约25%。上述结果为进一步研究抗生素在环境中的毒理效应提供了基础依据。     

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.     

Effects of sepiolite on stabilization remediation of heavy metal-contaminated soil and its ecological evaluation

Stabilization in the remediation of heavy metal contaminated soils has been gaining prominence because of its cost-effectiveness and rapid implementation. In this study, microbial properties such as microbial community and enzyme activities, chemical properties such as soil pH and metal fraction, and heavy metal accumulation in spinach (Spinacia oleracea) were considered in assessing stabilization remediation effectiveness using sepiolite. Results showed that soil pH values increased with rising sepiolite concentration. Sequential extraction results indicated that the addition of sepiolite converted significant amounts of exchangeable fraction of Cd and Pb into residual form. Treatments of sepiolite were observed to reduce Cd and Pb translocation from the soil to the roots and shoots of spinach. Concentrations of Cd and Pb exhibited 12.6%–51.0% and 11.5%–46.0% reduction for the roots, respectively, and 0.9%–46.2% and 43.0%–65.8% reduction for the shoots, respectively, compared with the control group. Increase in fungi and actinomycete counts, as well as in catalase activities, indicated that soil metabolic recovery occurred after sepiolite treatments.     

Key features of new particle formation events at background sites in China and their influence on cloud condensation nuclei

New particle formation (NPF) event at multi rural sites in China Identifying the characteristics of NPF event Comparing NPF event between clean and polluted conditions Quantifying contribution to the cloud condensation nuclei Implication of climate and air quality Long-term continuous measurements of particle number size distributions with mobility diameter sizes ranging from 3 to 800 nm were performed to study new particle formation (NPF) events at Shangdianzi (SDZ), Mt. Tai (TS), and Lin’an (LAN) stations representing the background atmospheric conditions in the North China Plain (NCP), Central East China (CEC), and Yangtze River Delta (YRD) regions, respectively. The mean formation rate of 3-nm particles was 6.3, 3.7, and 5.8 cm⁻³·s⁻¹, and the mean particle growth rate was 3.6, 6.0, and 6.2 nm·h⁻¹ at SDZ, TS, and LAN, respectively. The NPF event characteristics at the three sites indicate that there may be a stronger source of low volatile vapors and higher condensational sink of pre-existing particles in the YRD region. The formation rate of NPF events at these sites, as well as the condensation sink, is approximately 10 times higher than some results reported at rural/urban sites in western countries. However, the growth rates appear to be 1–2 times higher. Approximately 12%–17% of all NPF events with nucleated particles grow to a climate-relevant size (>50 nm). These kinds of NPF events were normally observed with higher growth rate than the other NPF cases. Generally, the cloud condensation nuclei (CCN) number concentration can be enhanced by approximately a factor of 2–6 on these event days. The mean value of the enhancement factor is lowest at LAN (2–3) and highest at SDZ (~4). NPF events have also been found to have greater impact on CCN production in China at the regional scale than in the other background sites worldwide.     

Photochemical indicators of ozone sensitivity: application in the Pearl River Delta,China

Surface O₃ production has a highly nonlinear relationship with its precursors. The spatial and temporal heterogeneity of O₃-NO _x -VOC-sensitivity regimes complicates the control-decision making. In this paper, the indicator method was used to establish the relationship between O₃ sensitivity and assessment indicators. Six popular ratios indicating ozone-precursor sensitivity, HCHO/NO _y , H₂O₂/ HNO₃, O₃/NO _y , O₃/NO _z , O₃/HNO₃, and H₂O₂/NO _z , were evaluated based on the distribution of NO_x- and VOC-sensitive regimes. WRF-Chem was used to study a serious ozone episode in fall over the Pearl River Delta (PRD). It was found that the south-west of the PRD is characterized by a VOCsensitive regime, while its north-east is NO _x -sensitive, with a sharp transition area between the two regimes. All indicators produced good representations of the elevated ozone hours in the episode on 6 November 2009, with H₂O₂/HNO₃ being the best indicator. The threshold sensitivity levels for HCHO/NO_y, H₂O₂/HNO₃, O₃/NO _y , O₃/NO _z , O₃/HNO₃, and H₂O₂/NO _z were estimated to be 0.41, 0.55, 10.2, 14.0, 19.1, and 0.38, respectively. Threshold intervals for the indicators H₂O₂/HNO₃, O₃/NO _y , O₃/NO _z , O₃/HNO₃, and H₂O₂/NO _z were able to identify more than 95% of VOC- and NO _x -sensitive grids. The ozone episode on 16 November 16 2008 was used to independently verify the results, and it was found that only H₂O₂/HNO₃ and H₂O₂/NO _z were able to differentiate the ozone sensitivity regime well. Hence, these two ratios are suggested as the most appropriate indicators for identifying fall ozone sensitivity in the PRD. Since the species used for indicators have seasonal variation, the utility of those indicators for other seasons should be investigated in the future work.

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Chemical poison and regeneration of SCR catalysts for NOx removal from stationary sources

Selective catalytic reduction (SCR) of NO_x with NH₃ is an effective technique to remove NO_x from stationary sources, such as coal-fired power plant and industrial boilers. Some of elements in the fly ash deactivate the catalyst due to strong chemisorptions on the active sites. The poisons may act by simply blocking active sites or alter the adsorption behaviors of reactants and products by an electronic interaction. This review is mainly focused on the chemical poisoning on V₂O₅-based catalysts, environmental-benign catalysts and low temperature catalysts. Several common poisons including alkali/alkaline earth metals, SO₂ and heavy metals etc. are referred and their poisoning mechanisms on catalysts are discussed. The regeneration methods of poisoned catalysts and the development of poison-resistance catalysts are also compared and analyzed. Finally, future research directions in developing poisoning resistance catalysts and facile efficient regeneration methods for SCR catalysts are proposed.