2,3,7,8-TCDD的短期暴露对HepG2肝癌细胞内小分子代谢产物的影响

为了研究二恶英对细胞的代谢毒性,探究其肝毒性的作用机制,以二恶英中毒性最强的2,3,7,8-四氯代二苯并-对-二恶英(TCDD)为代表污染物,以HepG2肝癌细胞为受试对象,采用四甲基偶氮唑蓝(MTT)法和高效液相色谱/串联质谱法考察了TC-DD的24h暴露对HepG2细胞的增殖活性以及细胞的葡萄糖、氨基酸、尿素和甘油等小分子代谢物的影响。结果显示,短暂的TCDD暴露对HepG2细胞的增殖活性无显著影响。24h的TCDD暴露对细胞的葡萄糖消耗量无显著影响,但当TCDD浓度增至1nmol·L-1时,葡萄糖的消耗量表现出一定的降低趋势。0.01nmol·L-1TCDD就会使细胞脯氨酸和谷氨酸的合成能力下降,且谷氨酸的变化表现出明显的剂量-效应关系;TCDD可刺激细胞对缬氨酸、苏氨酸、酪氨酸、甲硫氨酸以及亮氨酸与异亮氨酸的吸收,并具有明显的浓度依赖性。随着TCDD浓度的增加,甘油和尿素产生量的降低趋势逐渐明显,1nmol·L-1TCDD处理24h后,甘油和尿素的产生量仅为对照组的1%和18%。研究表明,TCDD在短时间内使HepG2细胞内的一系列小分子代谢产物发生了不同程度的改变,且呈现出一定的剂量-效应关系。可见,TCDD可通过干扰HepG2肝癌细胞的代谢过程产生毒性。     

煤矸石废弃地中胜红蓟的重金属富集研究

采用粤东明山煤矿煤矸石粉与当地山林的普通黄土按不同比例混合而成的土壤中,4种重金属含量排序为Mn>Zn>Cu>Cd。在这些土壤中进行为期3个月(7、8、9月份)的胜红蓟栽培实验,然后测定植株重金属含量,其地下部分4种重金属含量排序与土壤一致,但地上部分Cu、Cd两者含量相差甚小,7月时Cu含量甚至低于Cd。胜红蓟(Ageratumconyzoides)对4种重金属的富集系数从大至小分别为Cd、Mn、Zn、Cu,且对Cd的富集系数大于3,对Cd显示出较强的富集作用。对Zn、Mn的转移能力较强,转移系数多大于1,对Cd的转移系数接近于1或大于1,但Cu均小于1。在煤矸石粉比例较低的土壤中,Zn、Cu、Mn 3种重金属的富集系数较大。Zn、Cu、Mn 3种重金属的富集系数在煤矸石比例较低的土壤中随生长期延长而升高,在比例较高的土壤中,地上部分的富集系数仍随生长期延长而上升,但地下部分8月至9月反而会有所下降。转移系数在不同月份无明显的规律性变化。胜红蓟虽然并非这些元素的超富集植物,但对于尾矿土壤中Cd、Zn、Mn污染有较好的修复效果,其适应性强、生长快、总体生物量大,可选作矿区土壤的修复植物。     

Contamination of rivers in Tianjin, China by polycyclic aromatic hydrocarbons

Tianjin urban/industrial complex is highly polluted by some persistent organic pollutants. In this study, the levels of 16 priority polycyclic aromatic hydrocarbons (PAHs) were tested in sediment, water, and suspended particulate matter (SPM) samples in 10 rivers in Tianjin. The total concentration of 16 PAHs varied from 0.787 to 1943 microg/g dry weight in sediment, from 45.81 to 1272 ng/L in water, and from 0.938 to 64.2 microg/g dry weight in SPM. The levels of PAHs in these media are high in comparison with values reported from other river and marine systems. Variability of total concentrations of PAHs in sediment, water, and SPM from nine different rivers is consistent with each other. No obvious trends of total PAHs concentration variations were found between upstream and downstream sediment, water, and SPM samples for most rivers, which indicate local inputs and disturbances along these rivers. The spatial distributions of three-phase PAHs are very similar to each other, and they are also similar to those found in topsoil. However, their chemical profiles are significantly different from that of topsoil. The change of profiles is consistent with the different aqueous transport capability of 16 PAHs. Low molecular weight PAHs predomination suggests a relatively recent local source and coal combustion source of PAHs in the study area.     

Evaluation of soil microbial toxicity of waste foundry sand for soil-related reuse

The relationship between the chemical con- taminants and soil microbial toxicity of waste foundry sand （WFS） was investigated. Five different types of WFS from typical ferrous, aluminum, and steel foundries in China were examined for total metals, leachable metals, and organic contaminants. The soil microbial toxicity of each WFS was evaluated by measuring the dehydrogenase activity （DHA） of a blended soil and WFS mixture and then comparing it to that of unblended soil. The results show that the five WFSs had very different compositions of metal and organic contaminants and thus exhibited very different levels of soil microbial inhibition when blended with soil. For a given WFS blended with soil in the range of 10wt.%-50wt.% WFS, the DHA decreased almost linearly with increased blending ratio. Furthermore, for a given blending ratio, the WFSs with higher concentrations of metal and organic contaminants exhibited greater microbial toxicity. Correlation analysis shows that the relationship between ecotoxicity and metal and organic contaminants of WFSs can be described by an empirical logarithmic linear model. This model may be used to control WFS blending ratios in soil-related applications based on chemical analysis results to prevent significant inhibition of soil microbial activity.     

Uptake of polycyclic aromatic hydrocarbons by maize plants

Roots and above-ground parts (tops) of maize plants, comprising cuticles, leaves and stems, have been exposed separately to polycyclic aromatic hydrocarbons (PAHs) by means of air-tight bicameral exposure devices. Maize roots and tops of plants directly accumulate PAHs from aqueous solutions and from air in proportion to exposure levels. Root and leaf concentration factors (log RCF and log LCF) are log-linear functions of log-based octanol-water partition coefficient (log Kow) and log-based octanol-air partition coefficient (log Koa). The PAHs' concentrations among cuticles, leaves and stems display good correlations with each other. PAH concentrations in each part of the plant tested correlated positively with atmospheric PAHs' concentrations. Comparisons between PAHs' concentrations of root epidermis and root tissue showed similar correlations. Bulk concentrations of contaminants in various plant tissues differed greatly, but these differences disappeared after normalization to lipid contents suggesting lipid-based partitioning of PAHs among maize tissues.     

湖泊富营养化评价的S型曲线通用表示式

在适当设定富营养化指标的“本底”值情况下 ,当指标值用对应于“本底”值的相对值表示时 ,可采用 S型曲线描述湖泊富营养化发展程度 ,从而公式中的参数可视为与指标特性无关 ,采用遗传算法对公式中的参数优化 ,得到对多项指标通用的富营养化程度的指数计算公式 ,并用广义对比因子赋权新方法计算富营养化综合指数。该评价方法物理意义明确 ,计算简单 ,使用方便 ,具有可比性和通用性     

Life cycle assessment of autoclaved aerated fly ash and concrete block production: a case study in China

Environmental Science and Pollution Research - With the rapid development of construction industry, consumption of concrete block has increased rapidly in China. As a kind of green building...     

A new method for water quality assessment: by harmony degree equation

Water quality assessment is an important basic work in the development, utilization, management, and protection of water resources, and also a prerequisite for water safety. In this paper, the harmony degree equation (HDE) was introduced into the research of water quality assessment, and a new method for water quality assessment was proposed according to the HDE: by harmony degree equation (WQA-HDE). First of all, the calculation steps and ideas of this method were described in detail, and then, this method with some other important methods of water quality assessment (single factor assessment method, mean-type comprehensive index assessment method, and multi-level gray correlation assessment method) were used to assess the water quality of the Shaying River (the largest tributary of the Huaihe in China). For this purpose, 2 years (2013–2014) dataset of nine water quality variables covering seven monitoring sites, and approximately 189 observations were used to compare and analyze the characteristics and advantages of the new method. The results showed that the calculation steps of WQA-HDE are similar to the comprehensive assessment method, and WQA-HDE is more operational comparing with the results of other water quality assessment methods. In addition, this new method shows good flexibility by setting the judgment criteria value HD₀ of water quality; when HD₀?=?0.8, the results are closer to reality, and more realistic and reliable. Particularly, when HD₀?=?1, the results of WQA-HDE are consistent with the single factor assessment method, both methods are subject to the most stringent “one vote veto” judgment condition. So, WQA-HDE is a composite method that combines the single factor assessment and comprehensive assessment. This research not only broadens the research field of theoretical method system of harmony theory but also promotes the unity of water quality assessment method and can be used for reference in other comprehensive assessment.     

低溶解氧污泥微膨胀污染物去除性能的研究

为了研究低溶解氧微膨胀状态下污染物的去除效果,采用SBR反应器,平均DO浓度为0.5～0.9 mg/L,通过好氧/缺氧(O/A)的运行方式,对污染物处理效果进行研究。结果表明：低溶解氧丝状菌污泥微膨胀状态下,SVI可稳定控制在200 mL/g左右,出水SS含量很低,COD去除率在80%以上,氨氮去除率90%以上,除磷效率在90%之上,出水水质良好,同时可以节约曝气量约46.7%。低溶解氧微膨胀状态下,可保证出水处理效果,污泥沉降性能影响小,同时可以节约动力费用。     

论多媒体英语教学

多媒体英语教学把传统英语教学的单调形象转化为动感形象,国内经济社会的发展也需要多媒体英语教学的展开。本文针对英语教学中存在的主要问题：缺乏人际交流、弱化学生主体地位、弱化教师主导作用,提出相关的教学对策：加强英语教学软件的开发与利用,精心设计和制作课件;熟练掌握教学内容;将传统教学媒体与多媒体课件紧密结合;树立对多媒体英语教学的正确认识。