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.     

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.     

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。     

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。     

Contamination of organochlorine pesticides in water and sediments from a waterbird-inhabited lake,East Central China

Seventeen organochlorine pesticides (OCPs) were investigated in the water and sediments from a waterbird-inhabited lake (Yangchaihu Lake) to evaluate their current pollution levels and potential risks. The concentrations of total OCPs in water and sediments were 10.12–59.75 ng/l and 4.25–27.35 ng/g dry weight, respectively. Hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) were the most abundant OCPs, while HCB and cyclodiene pesticides were detected with low levels. Levels of ∑OCPs (sum of 17 OCPs) at sites highly influenced by waterbirds were significantly higher than the sites with no significant waterbird populations (one-way ANOVA, P?相似文献   

活性炭纤维对水中酚类化合物的吸附特性

研究了活性炭纤维(actived carbon fiber,ACF)对模拟废水中苯酚、对氯苯酚、对硝基苯酚的吸附特性.采用扫描电子显微镜(SEM)对ACF的表面结构进行了表征.通过静态吸附试验,采用吸附热力学探讨了ACF对苯酚、对氯苯酚、对硝基苯酚模拟废水的机制,计算了有关的热力学函数.结果表明,ACF对它们的吸附速率很快,在酸性条件下吸附效果较好,相同条件下,去除率是苯酚(87%)<对氯苯酚(96%)<对硝基苯酚(99%).ACF对这3种物质的吸附都是自发的放热反应,属于物理吸附.吸附等温线能用Dubinin-Radushkevieh方程较好地拟合.     

污泥增活剂影响MBR处理效果试验研究

向一体式膜生物反应器(Membrane Bioreactor,MBR)中投加污泥增活剂,与普通MBR进行试验对比,考察了污泥增活剂-MBR复合工艺对污染物去除的强化作用及对混合液污泥特性的影响。结果表明,污泥增活剂不仅提高了COD和氨氮的去除效果,而且由于增活剂与污泥形成的生物团粒的有效作用使系统总氮去除率提高10%以上。污泥增活剂-MBR中污泥混合液胞外聚合物(extra-cellular polymeric substances,EPS)含量高于MBR,上清液溶解性微生物产物(soluble microbial products,SMP)和Zeta电位相对较低,及EPS与SMP和Zeta电位的变化对应规律,说明污泥增活剂使EPS含量升高,促进了污泥活性的提高。较低的SMP浓度将降低膜自身污染的程度,活性炭的作用可使泥饼层结构疏松,能够减缓泥饼层带来的膜通量下降。     

湿法消解-原子荧光光谱法同时测定地表水中的砷和汞

为提高检测效率、降低检测成本、提高检测的准确性,采用硝酸消解水样,断续流动进样,在KBH_4-酸体系中、最佳的仪器试验条件下,用原子荧光光谱法同时测定地表水中的砷和汞。实验结果表明:砷、汞检出限分别为0.109、0.0026μg/L,线性范围分别为0～40μg/L和0～2μg/L,精密度都是1.4%,加标回收率分别为93.5%～107%和96.0%～104%。表明该检测方法检出限低、干扰性小、精密度高、测定结果稳定,能够满足地表水中砷和汞同时测定要求。     

犀浦校区室内空气中甲醛污染现状

为保证西南交通大学犀浦校区广大学生和教师有一个安全健康的学习和工作环境,避免受到室内环境污染的影响,在问卷调查的基础上,确定了具有代表性的室内甲醛监测点,进行了室内环境中的甲醛浓度监测。根据监测结果,从装饰装修工程、室内环境检测验收等方面提出了具体的要求和措施,可为犀浦校区后续建设提供指导。     

酚降解菌株的分离、鉴定和在含酚废水生物处理中的应用

从石油化工厂的活性污泥和废水混合物中分离到10个降解酚的细菌菌株,经16S rRNA基因序列分析,5个菌株(PD1、PD2、PD6、PD7和PD39)被鉴定为假单胞菌(Pseudomonas sp.),4个菌株(PD4、PD5、PD8和PD9)为不动杆菌(Acinetobacter sp.),1个菌株(PD3)为丛毛单胞菌(Comamonas sp.).对假单胞菌(Pseudomonas sp.)PD39菌株的酚降解特性、最适生长条件、降解底物的范围、儿茶酚1,2-双加氧酶(C12O)和儿茶酚2,3-双加氧酶(C23O)活性、含酚废水的生物处理等,进行了详细研究.结果表明,PD39菌株的最适生长和降解条件是,培养基的起始pH为7.0,培养温度为30℃,酚浓度为800 mg/L,对酚的最大降解浓度为1 200 mg/L.酚浓度为637 mg/L的工业废水经72 h处理酚的去除率达到99.96%.PD39菌株有很好的应用潜力来作含酚废水活性污泥处理系统的强化菌株.