城市生活垃圾中纤维素含量测定方法优化

对传统硫酸法进行改进,建立适用于城市生活垃圾纤维素含量的测定方法。以脂肪抽提时间、硫酸浓度、水解反应温度、水解反应时间、稀释硫酸浓度、回流时间为考察因素进行6因素5水平正交实验。结果表明,测定纤维素含量的最佳条件为：脂肪抽提时间4h、硫酸浓度70％、水解反应温度30℃、水解反应时间5h、稀释硫酸浓度5％、回流时间3h。优化后纤维素测定条件RSD均小于1．69％,平均回收率98．76％,表明该方法的精度高,可靠行强。     

污泥好氧颗粒化过程中微生物群落结构的演变与分析

为了揭示颗粒污泥形成过程中微生物群落结构多样性的演变过程,以人工配水为进水,在SBR中采用厌氧/好氧循环的手段成功培育出具有聚磷特性的颗粒污泥,利用基于16S rDNA的PCR-DGGE技术获得了微生物群落的DNA特征指纹图谱,对条带进行了统计分析和切胶测序,并建立了系统发育树。结果表明,污泥沉降性能的改善要先于颗粒污...     

Cadmium accumulation in and tolerance of rice (Oryza sativa L.) varieties with different rates of radial oxygen loss

Cadmium (Cd) uptake and tolerance were investigated among 20 rice cultivars based on a field experiment (1.2 mg Cd kg⁻¹ in soil) and a soil pot trial (control, 100 mg Cd kg⁻¹), and rates of radial oxygen loss (ROL) were measured under a deoxygenated solution. Significant differences were found among the cultivars in: (1) brown rice Cd concentrations (0.11-0.29 mg kg⁻¹) in a field soil, (2) grain Cd tolerance (34-113%) and concentrations (2.1-6.5 mg kg⁻¹) in a pot trial, and (3) rates of ROL (15-31 mmol O₂ kg⁻¹ root d.w. h⁻¹). Target hazard quotients were calculated for the field experiment to assess potential Cd risk. Significant negative relationships were found between rates of ROL and concentrations of Cd in brown rice or straw under field and greenhouse conditions, indicating that rice cultivars with higher rates of ROL had higher capacities for limiting the transfer of Cd to rice and straw.     

The differentially-expressed proteome in Zn/Cd hyperaccumulator Arabis paniculata Franch. in response to Zn and Cd

The Zn/Cd hyperaccumulator Arabis paniculata is able to tolerate high level of Zn and Cd. To clarify the molecular basis of Zn and Cd tolerance, proteomic approaches were applied to identify proteins involved in Zn and Cd stress response in A. paniculata. Plants were exposed to both low and high Zn or Cd levels for 10 d. Proteins of leaves in each treatment were separated by 2-DE (two-dimensional electrophoresis). Nineteen differentially-expressed proteins upon Zn treatments and 18 proteins upon Cd treatments were observed. Seventeen out of 19 of Zn-responsive proteins and 16 out of 18 of Cd-responsive proteins were identified using MALDI-TOF/TOF-MS (matrix-assisted laser desorption/ionization time of flight mass spectrometry). The most of identified proteins were known to function in energy metabolism, xenobiotic/antioxidant defense, cellular metabolism, protein metabolism, suggesting the responses of A. paniculata to Zn and Cd share similar pathway to certain extend. However, the different metal defense was also revealed between Zn and Cd treatment in A. paniculata. These results indicated that A. paniculata against to Zn stress mainly by enhancement of energy metabolism including auxin biosynthesis and protein metabolism to maintain plant growth and correct misfolded proteins. In the case of Cd, plants adopted antioxidative/xenobiotic defense and cellular metabolism to keep cellular redox homeostasis and metal-transportation under Cd stress.     

Hemoglobin (Hb) immobilized on amino-modified magnetic nanoparticles for the catalytic removal of bisphenol A

Catalytic removal of bisphenol A from aqueous solution with hemoglobin immobilized on amino-modified magnetic nanoparticles as an enzyme catalyst was reported. The amino-modified magnetite nanoparticles were firstly prepared by the coprecipitation of Fe²⁺ and Fe³⁺ with NH₃·H₂O and then modified by 3-aminopropyltriethoxysilane. The immobilization process was optimized by examining enzyme concentration, glutaraldehyde concentration, cross-link time, and immobilization time. The optimum conditions for the removal of bisphenol A with immobilized hemoglobin were also investigated. Under the optimality conditions, the removal efficiency of bisphenol A was about 80.3%. The immobilization had a beneficial effect on the stability of hemoglobin and conversions of bisphenol A. According to the proposed breakdown pathway and the intermediates, the enzyme-catalytic removal of bisphenol A by the immobilized hemoglobin is considered to be an effective method.     

Effects of phenanthrene on the mortality, growth, and anti-oxidant system of earthworms (Eisenia fetida) under laboratory conditions

To assess the toxic effects of phenanthrene on earthworms, we exposed Eisenia fetida to artificial soils supplemented with different concentrations (0.5, 2.5, 12.5, mgkg(-1) soil) of phenanthrene. The residual phenanthrene in the soil, the bioaccumulation of phenanthrene in earthworms, and the subsequent effects of phenanthrene on growth, anti-oxidant enzyme activities, and lipid peroxidation (LPO) were determined. The degradation rate of low concentrations of phenanthrene was faster than it was for higher concentrations, and the degradation half-life was 7.3d (0.5 mgkg(-1)). Bioaccumulation of phenanthrene in the earthworms decreased the phenanthrene concentration in soils, and phenanthrene content in the earthworms significantly increased with increasing initial soil concentrations. Phenanthrene had a significant effect on E. fetida growth, and the 14-d LC(50) was calculated as 40.67 mgkg(-1). Statistical analysis of the growth inhibition rate showed that the concentration and duration of exposure had significant effects on growth inhibition (p<0.001). Superoxide dismutase (SOD) activity increased at the beginning (2 and 7d) and decreased in the end (14 and 28 d). Catalase (CAT) activity in all treatments was inhibited from 1 to 14 d of exposure. However, no significant perturbations in malondialdehyde (MDA) content were noted between control and phenanthrene-treated earthworms except after 2d of exposure. These results revealed that bioaccumulation of phenanthrene in E. fetida caused concentration-dependent, sub-lethal toxicity. Growth and superoxide dismutase activity can be regarded as sensitive parameters for evaluating the toxicity of phenanthrene to earthworms.     

废弃电路板中环氧树脂真空热解规律的研究

真空条件下,应用程序升温管式电炉对废弃电路板中环氧树脂热解规律进行了研究.考察了不同的热解终温(200～700 ℃)、升温速率(5～30 ℃/min)、真空度(以压力表征,3～30 kPa)及保温时间(10～150 min)对热解产物产率的影响.实验结果表明,热解终温是影响热解油产率最重要的因素;选择适当的热解终温(400～550 ℃)、升温速率(15～20 ℃/min)、真空度(15 kPa)及保温时间(30 min)有利于提高热解油产率.     

“中老龄”垃圾渗滤液重金属和氨氮的厌氧毒性

通过厌氧毒性试验（ATA）研究了“中老龄”垃圾渗滤液的重金属和氨氮对厌氧微生物的毒性抑制作用。试验结果表明,“中老龄”垃圾渗滤液中的重金属和氨氮使厌氧污泥产甲烷活性分别下降14.4%和36.7%,4倍受试渗滤液重金属浓度或4 000 mg/L的氨氮浓度均可使污泥活性受到重度抑制。通过对不同浓度重金属和氨氮的厌氧毒性的关系进行回归分析,得出氨氮和重金属对厌氧微生物的IC50分别为2 265 mg/L和2.9倍试验用渗滤液的重金属浓度;“中老龄”垃圾渗滤液中氨氮对厌氧污泥的毒性影响较大,高浓度重金属对厌氧污泥活性的抑制较难恢复;实际渗滤液处理工艺中,在采用厌氧工艺前,应对氨氮进行预处理以减少其对厌氧微生物的毒性作用,同时避免水质剧烈波动对厌氧处理系统的冲击。     

Effects of aging and sediment composition on hexachlorobenzene desorption resistance compared to oral bioavailability in rats

Studies were conducted to assess the effects of black carbon, clay type and aging (1-1.5yr) on desorption and bioavailability of hexachlorobenzene (HCB) in spiked artificial sediments. Tenax (a super sorbent)-mediated desorption was used to examine the effects of these parameters on the physicochemical availability of HCB. The Tenax-mediated desorption of HCB from the four aged artificial sediments exhibited biphasic kinetics. The fast desorbing fractions ranged from 64.8% to 22.3%, showing reductions of 4.0-18.9% compared with freshly-spiked sediments. Statistical analysis on the fast desorbing fractions showed that all three treatment effects (i.e., montmorillonite clay, black carbon content, and aging) were significant. Two sediments with higher black carbon content exhibited much greater aging effects (i.e., greater reduction in fast desorbing fraction) than the other two sediments without the addition of black carbon. For both freshly-spiked and aged sediments, the desorption resistant sediment-bound HCB (i.e., slow desorbing fraction) correlated reasonably well to previously reported rat fecal elimination of HCB, which is a measure of the non-bioavailable fraction of sediment-bound HCB. A similar correlation was also observed between fast desorbing fraction and previously reported accumulation of HCB in the rat body (carcass+skin). These observations suggest that physicochemical availability, as defined by the desorption of HCB from sediments, provides a reasonable prediction of the oral bioavailability of sediment-bound HCB to rats. These results showed that montmorillonite clay, black carbon and aging reduced physicochemical availability and ultimately bioavailability of sediment-bound HCB.