Measurement of hydrogen peroxide and organic hydroperoxide concentrations during autumn in Beijing, China

Gaseous peroxides play important roles in atmospheric chemistry. To understand the pathways of the formation and removal of peroxides, atmospheric peroxide concentrations and their controlling factors were measured from 7:00 to 20:00 in September, October, and November 2013 at a heavily trafficked residential site in Beijing, China, with average concentrations of hydrogen peroxide (H₂O₂) and methyl hydroperoxide (MHP) at 0.55 ppb and 0.063 ppb, respectively. H₂O₂ concentrations were higher in the afternoon and lower in the morning and evening, while MHP concentrations did not exhibit a regular diurnal pattern. Both H₂O₂ and MHP concentrations increased at dusk in most cases. Both peroxides displayed monthly variations with higher concentrations in September. These results suggested that photochemical activity was the main controlling factor on variations of H₂O₂ concentrations during the measurement period. Increasing concentrations of volatile organic compounds emitted by motor vehicles were important contributors to H₂O₂ and MHP enrichment. High levels of H₂O₂ and MHP concentrations which occurred during the measurement period probably resulted from the transport of a polluted air mass with high water vapor content passing over the Bohai Bay, China.     

Fungal degradation of metsulfuron-methyl in pure cultures and soil

A fungal strain capable of utilizing metsulfuron-methyl as sole carbon and energy sources was isolated from a metsulfuron-methyl treated soil. The degradation characteristics of metsulfuron-methyl by this fungal strain were investigated in liquid culture and soil. More than 79% of metsulfuron-methyl at concentrations of 0.10 mgl(-1), 1.0 mgl(-1) and 10.0 mgl(-1) in pure culture was degraded by strain MD after incubation for 7 days, whereas only 5.6%, 8.6% and 13.1% of metsulfuron-methyl were degraded at levels of 0.10 mgl(-1), 1.0mgl(-1) and 10.0 mgl(-1) in the controls, respectively. The incorporation of strain MD into soil was found to substantially increase the degradation of metsulfuron-methyl. Degradation was 7.5 and 3.8 times faster in strain MD amended soils than in sterilized and fresh soils. The results show that addition of the isolated strain MD enhances degradation of metsulfuron-methyl in water and soil.     

House dust mite allergens and nitrated products:Identification and risk assessment in indoor dust

Air pollutants can potentially lead to nitration of allergic proteins, thus promoting sensitization of these allergens. However, little is currently known about the nitration status of house dust mite(HDM) allergens. We identified the occurrence of nitrated products of two major HDM allergens Der f 1 and Der p 1 in dust samples collected from college dormitories in eastern China and assessed their associated health risk. The results showed that both non-nitrated and nitrated forms of the two all...     

Hydrocarbon synthesis by enzymatically dissociated oenocytes of the abdominal integument of the German Cockroach,<Emphasis Type="Italic"> Blattella germanica</Emphasis>

In insects, hydrocarbons waterproof the cuticle, protect the insect from the external environment, and serve as semiochemicals or their metabolic precursors. In the German cockroach, Blattella germanica, hydrocarbons are synthesized by the abdominal integument, but the precise site of biosynthesis is not known. We developed a method for separation of oenocytes from other cells in the abdominal integument using enzymatic dissociation followed by Percoll gradient centrifugation. Radiolabeled propionate was then used to monitor de novo synthesis of hydrocarbons by dissociated cells. Oenocyte-enriched cell suspensions of abdominal sternites synthesized hydrocarbons, whereas suspensions enriched with epidermal cells did not. Our results show conclusively that hydrocarbons are produced by oenocytes not only in insects whose oenocytes are localized within the hemocoel, but also in those insects whose oenocytes are within the abdominal integument. Furthermore, these data support a hemolymph pathway for transport and delivery of hydrocarbons to both external and internal tissues, including the epicuticle, fat body, and ovaries.     

Function Zoning of the Major Function Development-optimized County： A Case in Shangyu,Zhejiang

The 11 th Five Year Plan has divided national functional zones in the basic unit of county-level administrative region. Af- ter implementation of national Major Function-oriented Zones (MFOZ) at prefec...     

Investigating the effect of volatility on the hygroscopicities of acetate nanoparticle aerosols by surface plasmon resonance microscopy

Under high relative humidity(RH) conditions, the release of volatile components(such as acetate) has a significant impact on the aerosol hygroscopicity. In this work, one surface plasmon resonance microscopy(SPRM) measurement system was introduced to determine the hygroscopic growth factors(GFs) of three acetate aerosols separately or mixed with glucose at different RHs. For Ca(CH₃COO)₂ or Mg(CH₃COO)₂ aerosols, the hygroscopic growth trend of each time...     

Alleviating eutrophication by reducing the abundance of Cyanophyta due to dissolved inorganic carbon fertilization: Insights from Erhai Lake,China

The eutrophication of lakes is a global environmental problem. Regulating nitrogen(N) and phosphorus(P) on phytoplankton is considered to be the most important basis of lake eutrophication management. Therefore, the effects of dissolved inorganic carbon(DIC) on phytoplankton and its role in mitigating lake eutrophication have often been overlooked. In this study, the relationships between phytoplankton and DIC concentrations, carbon isotopic composition, nutrients(N and P), and hydrochemistry in...     

Potential Environmental Benefits from Increased Use of Bioenergy in China

Because of its large population and rapidly growing economy, China is confronting a serious energy shortage and daunting environmental problems. An increased use of fuels derived from biomass could relieve some demand for nonrenewable sources of energy while providing environmental benefits in terms of cleaner air and reduced emissions of greenhouse gases. In 2003, China generated about 25.9 × 10⁸ metric tons of industrial waste (liquid + solid), 14.7 × 10⁸ metric tons/year (t/y) of manure (livestock + human), 7.1 × 10⁸ t/y of crop residues and food-processing byproducts, 2 × 10⁸ t/y of fuelwood and wood manufacturing residues, and 1.5 × 10⁸ t/y of municipal waste. Biofuels derived from these materials could potentially displace the use of about 4.12 × 10⁸ t/y of coal and 3.75 × 10⁶ t/y of petroleum. An increased bioenergy use of this magnitude would help to reduce the emissions of key air pollutants: SO₂ by 11.6 × 10⁶ t/y, NO_X by 1.48 × 10⁶ t/y, CO₂ by 1.07 × 10⁹ t/y, and CH₄ by 50 × 10⁶ t/y. The reduced SO₂ emissions would be equivalent to 54% of the national emissions in 2003, whereas those for CO₂ are 30%. It is important to recognize, however, that large increases in the use of biomass fuels also could result in socioeconomic and environmental problems such as less production of food and damage caused to natural habitats.     

La/Ce-codoped Bi2O3 composite photocatalysts with high photocatalytic performance in removal of high concentration dye

A series of La/Ce-codoped Bi_2O_3 composite photocatalysts were fabricated via hydrothermal–calcination process. The as-prepared products were intensively characterized by some physicochemical characterizations like N_2 physical adsorption, X-ray powder diffraction(XRD), scanning electron microscope(SEM), transmission electron microscope(TEM), UV–Vis diffuse reflectance(UV–Vis DRS), Fourier transform infrared spectroscopy(FT-IR),photoelectrochemical measurements, and photoluminescence(PL) spectroscopy. The characterization results indicated that La and Ce doping induced obvious crystal phase transformation in Bi_2O_3, from monoclinic to tetragonal phase. La and Ce codoping also gave rise to the obvious synergetic effects, e.g., the lattice contraction of Bi_2O_3, the decrease of crystal size and the increase of surface area. The photocatalytic performance of the prepared catalysts was evaluated by removal of dye acid orange II with high concentration under visible light irradiation. Results showed that La/Ce-codoped Bi_2O_3 displayed much higher photocatalytic performance than that of bare Bi_2O_3, single La or Ce doped Bi_2O_3 samples. The superior photocatalytic activity was mainly attributed to the improved texture and surface properties and the synergistic effects of La and Ce codoping on suppressing the recombination of photo-generated electrons(e~-) and holes(h~+).