Removing lignin model pollutants with BiFeO3–g-C3N4 compound as an efficient visible-light-heterogeneous Fenton-like catalyst

BiFeO_3–g-C_3N_4 nanoscaled composite was prepared with a hydrothermal method and evaluated as a highly efficient photo-Fenton like catalyst under visible light irradiation. The BiFeO_3–g-C_3N_4 composite exhibited much stronger adsorption ability to lignin model pollutant(guaiacol) than that of BiFeO_3, which may be due to the higher specific surface area(BiFeO_3–g-C_3N_4: 35.59 m~2/g BiFeO_3: 7.42 m~2/g) and the adsorption form of π–π stack between g-C_3N_4 and guaiacol. The composite exhibited excellent visible light-Fenton like catalysis activity, being influenced by the solution pH value and the proportions of BiFeO_3 and g-C_3N_4 nanosheets. Under optimal conditions with visible light irradiation, the BiFeO_3–g-C_3N_4 composite yielded fast degradation of guaiacol with an apparent rate constant of 0.0452 min~(-1), which were 5.21 and 6.80 folds of that achieved by using BiFeO_3 and the mixture of BiFeO_3 and g-C_3N_4 nanosheets, respectively. The significantly enhanced visible light-Fenton like catalytic properties of the BiFeO_3–g-C_3N_4 composite in comparison with that of BiFeO_3 was attributed to a large surface area, much increased adsorption capacity and the semiconductor coupling effect between BiFeO_3 and g-C_3N_4 in the composite.     

重度富营养化水培条件下烟草的生长特性及其净化效果的研究

研究了烟草在重度富营养化水培条件下的生长特性、根的解剖结构,对其净化效果进行了观测,并对烟草在重度富营养化水中的生长特性变化原因、适应机理进行了探讨.     

Cattle manure biochar and earthworm interactively affected CO2 and N2O emissions in agricultural and forest soils: Observation of a distinct difference

• Earthworms increase CO₂ and N₂O emissions in agricultural and forest soil. • 10% biochar suppresses CO₂ and N₂O emissions in forest soil. • Biochar interacted with earthworm to significant affect CO₂ and N₂O emissions. The application of manure-derived biochar offers an alternative to avoid the direct application of manure to soil causing greenhouse gas emission. Soil fauna, especially earthworms, can markedly stimulate carbon dioxide (CO₂) and nitrous oxide (N₂O) emissions from soil. This study therefore investigated the effect of cattle manure biochar (added at rates of 0, 2%, or 10%, coded as BC0, BC2 and BC10, respectively) application, with or without earthworm Aporrectodea turgida, on emissions of CO₂ and N₂O and changes of physic-chemical properties of agricultural and forest soils in a laboratory incubation experiment. The BC10 treatment significantly enhanced cumulative CO₂ emissions by 27.9% relative to the untreated control in the agricultural soil. On the contrary, the BC2 and BC10 treatments significantly reduced cumulative CO₂ emissions by 16.3%–61.1% and N₂O emissions by 92.9%–95.1% compared to the untreated control in the forest soil. The addition of earthworm alone significantly enhanced the cumulative CO₂ and N₂O fluxes in agricultural and forest soils. Cumulative CO₂ and N₂O fluxes were significantly increased when BC2 and BC10 were applied with earthworm in the agricultural soil, but were significantly reduced when BC10 was applied with earthworm in the forest soil. Our study demonstrated that biochar application interacted with earthworm to affect CO₂ and N₂O emissions, which were also dependent on the soil type involved. Our study suggests that manure biochar application rate and use of earthworm need to be carefully studied for specific soil types to maximize the climate change mitigation potential of such management practices.     

赤水河流域仁怀市生态保护态度与行为研究

通过调查问卷的形式探索了仁怀市赤水河两岸的村民在生态保护中的态度与行为。结果表明:沿赤水河两岸居住的部分村民的环保意识相对较低,居民的环保意识与所受教育程度有关,且居民了解环保知识的渠道单一,需要加强多渠道宣传;居民的日常生活和农耕对赤水河的污染较小,周围酒厂及小工厂的污染"贡献"较大。当地环保部门应该加强宣传,提高两岸居民的环保知识水平,减少生活污染,严格控制企业污染排放,减少工业污染,从而维护赤水河流域生态安全。     

A practical application of Driscoll's equation for predicting the acid-neutralizing capacity in acidic natural waters equilibria with the mineral phase gibbsite

A practical application of Driscoll's equation for predicting the acid-neutralizing capacity (ANC) in acidic waters equilibria with the mineral phase gibbsite is reported in this paper. Theoretical predication values of ANC are compared with the experimental data obtained from different literatures. The effect of aluminum (Al) on the value of ANC is investigated. It indicates that Al plays an important role in regulating the buffering effects in acidic natural waters. Failure to consider Al in acidic waters may bias assessment results in certain situations so as to overestimate the ANC values in response to increase in atmospheric deposition.     

Dynamics of aluminum speciation in forest-well drainage waters from the Rhode River watershed, Maryland

This paper reports an investigation of the dynamics of aluminum (Al) speciation in the forest-well waters from study site 110 of the Rhode River watershed, a representative sub-unit of Chesapeake Bay. Seasonal changes of Al speciation are evaluated by a modified MINEQL computer model using chemical equilibrium calculation. It was found that Al-F and Al-Org complexes were the dominate forms, whereas toxic forms of Al3+ and Al-OH were not significant. This indicates that Al toxicity is not very serious in the Rhode River area due to the high concentrations of fluoride and organic materials, even though sometimes pH is very low (approximately 4). Increased H+ or some other associated factors may be responsible for the decline in fish and amphibian population on the watershed.     

Assessing the impact of urbanization on regional net primary productivity in Jiangyin County, China

Urbanization is one of the most important aspects of global change. The process of urbanization has a significant impact on the terrestrial ecosystem carbon cycle. The Yangtze Delta region has one of the highest rates of urbanization in China. In this study, carried out in Jiangyin County as a representative region within the Yangtze Delta, land use and land cover changes were estimated using Landsat TM and ETM+ imagery. With these satellite data and the BEPS process model (Boreal Ecosystem Productivity Simulator), the impacts of urbanization on regional net primary productivity (NPP) and annual net primary production were assessed for 1991 and 2002. Landsat-based land cover maps in 1991 and 2002 showed that urban development encroached large areas of cropland and forest. Expansion of residential areas and reduction of vegetated areas were the major forms of land transformation in Jiangyin County during this period. Mean NPP of the total area decreased from 818 to 699 gCm(-2)yr(-1) during the period of 1991 to 2002. NPP of cropland was only reduced by 2.7% while forest NPP was reduced by 9.3%. Regional annual primary production decreased from 808 GgC in 1991 to 691 GgC in 2002, a reduction of 14.5%. Land cover changes reduced regional NPP directly, and the increasing intensity and frequency of human-induced disturbance in the urbanized areas could be the main reason for the decrease in forest NPP.     

Assessment of comparative toxicities of lead and copper using plant assay

The acute toxicities of lead (Pb) and copper (Cu) to important crop plants Sorghum bicolor, Cucumis sativus, Triticum aestivum, and Zea mays were compared. The EC50 values (the concentration of metals in the soil that reduces the growth of shoots and roots by 50%) were derived using the Trimmed Spearman-Karber method. The EC50s-shoot (root) in mg Pb kg-1 dry soil and mg Cu kg-1 dry soil were in the range of 519 to >1280 (285-445), and 48-232 (<40-110), respectively. Those concentrations are likely to occur in some abandoned mine areas in Korea. The figures indicate that Cu is more toxic than Pb to the plants in this study, and that root growth is more sensitive to the toxicity endpoint than shoot growth in Cu- or Pb-amended soils. On the other hand, seed germination is insensitive to both Pb and Cu toxicities. The Pb- and Cu-sensitive plants were also identified. Among the plants tested, T. aestivum and S. bicolor were most sensitive to Pb and Cu, respectively. Z. mays was most resistant to both Pb and Cu. The combined effects of Pb and Cu depend on the plant species, and no general phenomenon was observed. Bioaccumulations of Pb and Cu were observed in all test species, and they are concentration-dependent. These differences in the toxicities of Pb and Cu in plant species should be taken into account in biomonitoring and ecological risk assessment.     

微电解法预处理咖啡因生产废水及机理研究

采用微电解法预处理咖啡因生产废水,考察了进水pH、反应时间、进水浓度、铁炭比等因素对废水处理效果的影响。实验结果表明;进水为pH3、反应时间为60min、原水进水(COD16585mg/L,BOD53814mg/L,ρ(氨氮)640mg/L)、铁炭比(堆积体积比)为1∶1时,废水的COD去除率为46.8%,氨氮去除率为62.6%,脱色率为93.5%,并对重金属有良好的去除效果。气相色谱-质谱分析结果表明,微电解可以将废水中的含氮杂环物质转化为胺类和脲类等链状易生物降解的小分子物质。     

钛基锡锑电极电催化氧化处理硝基苯废水

采用钛基锡锑(Sn-Sb/Ti)电极作为氧化阳极,不锈钢为阴极,电催化氧化降解废水中硝基苯。实验结果表明,处理硝基苯废水的最佳条件为:电流密度25 mA/cm~2;Na_2SO_4作为电解质,加入量15g/L;极板间距2 cm;溶液初始pH 6。在此最佳条件下,硝基苯去除率大于95%,TOC去除率大于80%,表明Sn-Sb/Ti阳极能有效去除废水中有机污染物。