Effects of di-n-butyl phthalate on the physiology and ultrastructure of cucumber seedling roots

Agricultural pollution caused by the use of plastic sheetings has been documented to be a widespread problem in most of the major crop-planting regions of the world. In order to better understand the phytotoxic mechanisms induced by phthalic acid esters involved with this problem, Cucumber sativus L. cv Jinyan No. 4 were sown in pots to the three-leaf-stage in the presence of di-n-butyl phthalate (DBP; 0, 30, 50, 100, and 200 mg L^?1) for 1, 3, 5, or 7 days. Physiology, biochemistry, and ultrastructure of seedling roots were examined. The results indicated that activities of three antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD)) were stimulated at low-DBP treatments and decreased under higher levels (>100 mg L^?1) compared to the controls. On the other hand, SOD and POD provided a better defense against DBP-induced oxidative damage in the roots of cucumber seeding, compared to CAT. The productions of both malondialdehyde (MDA) and proline (Pro) were promoted under DBP stress. Visible impact on the cytoderm, mitochondrion, and vacuole was detected, possibly as a consequence of free radical generation. These results suggested that activation of the antioxidant system by DBP led to the formation of reactive oxygen species that resulted in cellular damage.     

间歇曝气潜流人工湿地的污水脱氮效果

采用间歇曝气运行方式,提升潜流人工湿地生活污水处理系统中的溶解氧浓度,强化脱氮效果。结果表明,间歇曝气运行方式有效提高了湿地内部溶解氧水平,曝气时溶解氧浓度可达6~9 mg/L,停止曝气后,溶解氧浓度迅速下降至0.5 mg/L以下,在湿地内部营造了一种交替的好氧和缺氧环境,分别促进好氧硝化和缺氧反硝化作用。在水力停留时间为3 d的情况下,间歇曝气潜流人工湿地系统对氨氮、总氮和COD的去除率分别可达到98.0%、87.6%和96.3%,较常规潜流人工湿地系统分别提高了74.1%、56.4%和18.1%,实现了氨氮、总氮和COD的同步高效去除。     

污泥膜覆盖好氧发酵堆体流场模拟及应用研究简

运用Gambit软件建立了污泥好氧发酵堆体的多孔介质模型,通过自行设计的实验装置获得了堆体的通风粘性阻力系数和惯性阻力系数以及功能膜压差与透气量之间的关系,用Fluent软件分析了堆体不同截面形状及底部通风管数量对堆体通风均匀性的影响,为确定合理的通风管数量及截面几何形状提供理论依据。对上海奉贤区城镇污水厂污泥处理工程发酵仓进行堆体流场模拟,确定堆体采用小拱形截面形状,堆高2 m,宽8 m,底部设置4条通风管,实际运行效果良好。     

响应面法优化甘蔗渣-污泥复合活性炭的制备工艺

为了提高污泥活性炭的吸附性能以提升其实际应用价值,提出在污泥中掺杂甘蔗渣制备复合活性炭,并采用Plackett-Burman联用响应面法对影响复合活性炭碘值的条件进行筛选优化。通过Plackett-Burman实验筛选出热解温度、热解时间和甘蔗渣与污泥干重比为主要影响因素,对这3个因素进行Box-Behnken实验,经响应面优化得到影响碘值的二次响应曲面模型,模型显示热解温度与热解时间、热解温度与干重比的交互作用显著,并确定了最佳制备条件:热解温度550℃、热解时间30 min和干重比50%,此时复合活性炭碘值为814 mg/g,优于未优化条件下制备的复合活性炭。通过比表面积、孔结构和碘值的测定以及元素和扫描电镜分析得出,甘蔗渣的掺杂提高了复合活性炭的比表面积、微孔体积、碘值及含碳量。研究结果表明,甘蔗渣掺杂和制备条件优化是提高污泥活性炭吸附性能的有效手段。     

湖南省四水流域水沙周期特征及其影响因素分析

采用复小波变换和M K非参数检验的方法分析了湖南省四水流域主要控制站1951~2011年径流量与输沙量周期规律和突变特征。结果表明：(1)湖南四水径流量存在多个波动增加和波动减少的波动变化现象,但无显著变化趋势;而输沙量虽然有一定的波动,但总体上呈波动减少变化态势,而且下降趋势较显著;(2)湘潭站、桃江站和桃源站径流量和输沙量存在20~25 a的第一主周期,而石门站径流量和输沙量的第一主周期不具有一致性,径流量主周期为2 a,输沙量主周期为13 a,但其径流量和输沙量第二、三主周期变化规律相吻合,均为3~5 a的周期;(3)大量的水利工程建设是导致输沙量减少的主要原因,径流量的变化与降水的变化规律较为一致     

中国春季降水与南印度洋偶极子的关系研究

利用美国国家海洋和大气管理局海温资料和1951~2010年中国160站月降水量资料,分析了前期冬季（12~2月）印度洋海表温度与中国160站春季降水的关系及其影响机制。研究表明：冬季印度洋海温异常的空间模态主要有两种：符号一致的单极和东、西符号相反的南印度偶极。将第2模态的时间系数定义为南印度洋偶极子指数。该指数与中国次年春季降水关系较好,并利用NCEP/NCAR再分析资料进行机制分析,发现主要南印度洋偶极子通过以下途径影响中国春季降水：中高纬,SIOD的影响主要引起低纬度的海温及对流异常,通过中低纬度间的相互作用,在中高纬产生较强的遥响应,从而影响同期冬季欧亚大陆的环流变化,这种扰动在西风气流的作用下引起后期春季北太平洋地区对流活动异常,通过中低纬度间的相互作用,加强中高纬地区的遥响应,表现为欧亚大陆EUP波列;低纬,SIOD的影响主要引起南海-海洋性大陆的海温及对流异常,引发经向环流异常,导致黄河至长江中下游地区垂直运动异常和气流辐合异常     

Manganese concentrations in maternal–infant blood and birth weight

Manganese (Mn) is an essential mineral nutrient in mammals. The physiological role of Mn in animal models is well documented, but little is known about the adverse effects of Mn deficiency or overexposure in humans, including pregnancy outcomes such as birth weight. We examined the relationship of the maternal and cord blood Mn levels with birth weight in a cohort of 172 mother–infant pairs born in Shanghai, China. Non-linear spline and quadratic regression models were used to test the hypothesis of an inverted U-shaped association between the Mn levels and birth weight. The median (range) levels of Mn in the maternal and cord blood were 5.38 (2.34–30.37) μg/dL and 7.66 (2.57–34.23) μg/dL, respectively. An inverted U-shaped relationship was observed between maternal Mn and birth weight after adjusting for potential confounders. The birth weight increased with Mn levels up to 4.18 μg/dL, and a slight reduction in weight was observed at higher levels. The cord blood Mn levels were not found to be associated with birth weight. Both lower and higher Mn exposures are associated with lower birth weight, which may influence important developmental parameters; the association of higher Mn levels with lower weight was weak and imprecise.     

电渗透脱水对污泥热干燥特性的影响

以污水厂机械脱水后的污泥作为研究对象,提出了采用电渗透-热干燥结合进行深度脱水的方法。通过对原泥以及电渗透脱水至不同含水率(67%、71%和76%)的污泥在热干燥过程中含水率和干燥速率的测定,分析电渗透脱水对污泥热干燥特性的改善规律。结果表明,经电渗透脱水至含水率为67%和71%的污泥在热干燥过程中的传热传质速率及干燥速率有明显提高,且干燥温度越高,电渗透后污泥的干燥速率与原泥的干燥速率差距越大。相同电压梯度及相同温度下电渗透至67%后进行热干燥耗能最少。实际应用中应结合能耗分析选择合适的电渗透程度及干燥温度,以达到最优效果。     

Aquatic predicted no-effect concentration for three polycyclic aromatic hydrocarbons and probabilistic ecological risk assessment in Liaodong Bay of the Bohai Sea, China

Predicted no-effect concentration (PNEC) is often used in ecological risk assessment to determine low-risk concentrations for chemicals. In the present study, native marine species were selected for toxicity testing. The PNECs for three polycyclic aromatic hydrocarbons (PAHs), specifically phenanthrene (Phe), pyrene (Pyr), and benzo[a]pyrene (BaP), were derived from chronic and acute toxicity data with log-normal statistical methods. The achieved PNECs for Phe, Pyr, and BaP were 2.33, 1.09, and 0.011 μg/L, respectively. In Jinzhou Bay and the Shuangtaizi River Estuary of Liaodong Bay in the Bohai Sea, China, the surface water concentrations of the three PAHs were analyzed by gas chromatography–mass spectrometry. Based on two probabilistic ecological risk assessment (PERA) methods, namely probabilistic risk quotient and joint probability curve, the potential risk of Phe, Pyr, and BaP in Jinzhou Bay and Shuangtaizi River Estuary was assessed. The same order of ecological risk (BaP > Phe > Pyr) was found by both models. Our study considered regional characteristics of marine biota during the calculation of PNECs, and the PERA methods provided probabilities of potential ecological risks of chemicals. Within the study area, further research on BaP is required due to its high potential ecological risk.     

煤炭资源开采环境污染物影子价格的估计——基于安徽煤炭企业的调查数据

环境污染物的影子价格体现了污染物的边际减排成本,是政府制定公共环境政策的重要依据。本文在环境技术的基础上,扩展了传统的产出方向性距离函数方法,进而构建了能够将多种环境污染物的影子价格进行综合估测新的影子价格模型。采用这种新的模型方法和安徽煤炭开采和洗选企业的样本数据,对煤炭资源开采利用过程中排放的三种主要环境污染物——废水、废气和固体废物的影子价格进行了估计。结果发现,2009年,安徽煤炭开采和洗选企业所排放的废水、废气和固体废物的平均影子价格分别为0.021 6万元/t、0.031 37万元/t和0.178 48万元/t。这三种环境污染物的影子价格存在差异,反映出安徽煤炭开采企业处理不同环境污染物所面临的环境成本是不同的。环境行为监管者在做出环境规制决策前要充分考虑到这个前提。