土壤水分管理对甲烷和氧化亚氮排放的影响

为控制农田温室气体排放的途径提供依据,通过实验室培养的方法测定了不同水分管理条件下CH4和N2O的排放,干旱处理（60％-70％WFP）和长期淹水土样在施肥后的Eh变化。最终得出：稻田CH4和N2O排放之间存在着互为消长的关系（R2=0．609）,CH4和N2O的排放是水肥共同作用的结果,水分管理通过Eh来影响气体排放,有机质是造成前后期排放浓度差异的主要原因。     

The effect of emission trading system on infant health: evidence from China

Environmental Geochemistry and Health - Although existing literature has explored the effect of the emission trading system (ETS) on economic growth and pollution emissions, little is known about...     

Integrating life cycle assessment and a farmer survey of management practices to study environmental impacts of peach production in Beijing,China

Environmental Science and Pollution Research - While intensive peach production has expanded rapidly in recent years, few studies have explored the environmental impacts associated with specific...     

机械力化学活化HPW-TiO_2/膨润土光催化降解甲基橙

采用溶胶-凝胶法制备了磷钨酸(HPW)改性TiO_2,并固载于膨润土上,再经机械力化学活化,得到机械力化学活化HPW-TiO_2/膨润土(MCA-HPW-TiO_2/膨润土)复合光催化剂。采用XRD,SEM,EDS技术对复合光催化剂进行了表征,并将其用于甲基橙的紫外光催化降解。表征结果显示:活性组分TiO_2和HPW成功固载于膨润土上;在机械力化学活化作用下,膨润土层间结构遭到破坏,TiO_2的XRD特征峰形呈弥散状态。实验结果表明:机械力化学活化作用对HPW-TiO_2/膨润土的光催化性能提升效果显著;在酸性及近中性条件下MCA-HPWTiO_2/膨润土均具有较高的催化活性;在溶液p H 6.2、初始甲基橙质量浓度10 mg/L、反应时间180 min、MCAHPW-TiO_2/膨润土投加量1 g/L的条件下,甲基橙去除率达88.27%;该光催化降解过程符合一级动力学模型。     

An exploration of the relationship between adsorption and bioavailability of pesticides in soil to earthworm

A study was conducted to determine the adsorption/desorption of butachlor, myclobutanil and chlorpyrifos on five soils using a batch equilibration technique and to study the relationship between bioavailability to Allolobophora caliginosa and the adsorption/desorption of these three pesticides. The results showed that the adsorption/desorption processes of the tested compounds were mainly controlled by soil organic matter content (OM) and octanol/water-partitioning coefficient (K(ow)), and that the bioavailability of the pesticides was dependent on characteristics of pesticides, properties of soils, and uptake routes of earthworms. Bioconcentration of butachlor and myclobutanil was negatively correlated with Freundlich adsorption constant K(af) and K(df). However, only a slightly positive correlation between bioconcentration and K(af) and K(df) was observed for chlorpyrifos due to its high affinity onto soil.     

Increased leaf area expansion of hybrid poplar in elevated CO2. From controlled environments to open-top chambers and to FACE.

We examined the response of hybrid poplar to elevated CO2 in contrasting growth environments: controlled environment chamber (CE). open-top chamber (OTC) and poplar free air CO2 enrichment (POPFACE) in order to compare short versus long-term effects and to determine whether generalisations in response are possible for this fast growing tree. Leaf growth, which for poplar is an important determinant of stemwood productivity was followed in all environments, as were the determinants of leaf growth-cell expansion and cell production. Elevated CO2 (550-700 micromol mol(-1), depending on environment) resulted in an increase in final leaf size for Populus trichocarpa x Populus deltoides (Populus x interamericana) and P. deltoides x Populus nigra (Populus x euramericana), irrespective of whether plants were exposed during a short-term CE glasshouse study (90 days), a long-term OTC experiment (3 years) or during the first year of a POPFACE experiment. An exception was observed in the closed canopy POPFACE experiment, where final leaf size remained unaltered by CO2. Increased leaf extension rate was observed in elevated CO2 in all experiments, at some point during leaf development, as determined by leaf length. Again the exception were the POPFACE experiment, where effects were not statistically significant. Leaf production and specific leaf area (SLA) were increased and decreased, respectively, on five out of six occasions, although both were only statistically significant on two occasions and interestingly for SLA never in the FACE experiment. Although both cell expansion and cell production were sensitive to CO2 concentration, effects appeared highly dependent on growth environment and genotype. However, increased leaf cell expansion in elevated CO2 was often associated with changes in the biophysical properties of the cell wall, usually increased cell wall plasticity. This research has shown that enhanced leaf area development was a consistent response to elevated CO2 but that the magnitude of this response is likely to decline, in long-term exposure to elevated CO2. Effects on SLA and leaf production suggest that CE and OTC experiments may not always provide good predictors of the 'qualitative' effects of elevated CO2 in long-term ecosystem experiments.     

甲醛对小鼠造血调控相关转录因子在mRNA水平表达的影响

为了研究甲醛污染毒性的分子机制,探究了气态甲醛暴露对小鼠造血调控相关转录因子在mRNA水平表达产生的影响.实验将18只雄性Balb/C小鼠随机分为3组,每组6只,采用仿真式口鼻吸入方法暴露于不同浓度(0.5 mg·m-3和3.0 mg·m-3)的气态甲醛环境中,每天8 h,为期2周.染毒结束后,分别进行血细胞分析和RT-PCR测定小鼠骨髓相关髓系转录因子、红系和巨核系转录因子、淋巴系转录因子在mRNA水平的表达量.结果发现,与对照组相比,相关转录因子C/EBPα、SCL、GATA-2、c-myb、GATA-1及淋巴系转录因子在mRNA水平表达量随甲醛浓度的升高受到不同程度的影响,部分具有统计学差异(p0.05).其中,转录因子C/EBPα、SCL及GATA-2在mRNA水平表达量随甲醛浓度的升高而降低,而转录因子c-myb、GATA-1及淋巴系转录因子Ikzf5、PAX5在mRNA水平表达量随甲醛浓度的升高而升高.研究表明,高浓度甲醛暴露会影响小鼠骨髓造血调控相关转录因子的正常表达.     

Oxidative capacities of size-segregated haze particles in a residential area of Beijing

The frequent haze days around the Chinese capital of Beijing in recent years have aroused great attention owing to the detrimental efects on visibility and public health. To discover the potential health efects of the haze, oxidative capacities of airborne particles collected in Beijing during haze and clear days were comparably assessed by a plasmid scission assay. Eleven water-soluble trace elements(As, Cd, Cr, Cu, Mn, Ni, Pb, V, Se, Tl, and Zn) in the size-segregated airborne particles were quantitatively analyzed by inductively coupled plasma mass spectrometry, and most of the watersoluble trace elements were found to mainly concentrate in the fine particle size of 0.56–1.0 μm. In comparison with clear days, the mass concentrations of 11 analyzed water-soluble trace elements remarkably increased during haze days, and the oxidative capacities determined by the plasmid scission assay were markedly elevated accordingly during the haze days under the same dosage of particles as for those during clear days. Water-soluble trace elements in airborne particles, such as Cu, V, and particularly Zn, were found to have significantly positive correlations with the plasmid DNA damage rates. Because Cu, V, and Zn have been considered as bioavailable elements, the evident increase of these elements during haze days may be greatly harmful to human health.     

Humic acid transport in saturated porous media: Influence of flow velocity and influent concentration

Understanding the transport of humic acids（HAs） in porous media can provide important and practical evidence needed for accurate prediction of organic/inorganic contaminant transport in different environmental media and interfaces. A series of column transport experiments was conducted to evaluate the transport of HA in different porous media at different flow velocities and influent HA concentrations. Low flow velocity and influent concentration were found to favor the adsorption and deposition of HA onto sand grains packed into columns and to give higher equilibrium distribution coefficients and deposition rate coefficients, which resulted in an increased fraction of HA being retained in columns.Consequently, retardation factors were increased and the transport of HA through the columns was delayed. These results suggest that the transport of HA in porous media is primarily controlled by the attachment of HA to the solid matrix. Accordingly, this attachment should be considered in studies of HA behavior in porous media.