基于综合指数的湖北省耕地质量变化分析

在综合界定耕地质量内涵的基础上,构建了耕地质量变化的评价指标体系和评估模型,以此为基础,对1995—2005年湖北省耕地质量的动态变化进行了分析。研究表明:湖北省耕地综合质量变化总体呈现波动上升趋势,但体现耕地综合质量的耕地本底质量、经济质量与生态质量变化差异显著。耕地本底质量自20世纪90年代中期到本世纪初变化平缓,整体波动较小;耕地经济质量在1995—1999年间提升迅速,2000年后基本保持平稳,但最近几年有波动下降的趋势;耕地生态质量自20世纪90年代中期以来呈缓慢下降趋势,近几年下降趋势有所缓和;耕地综合质量在1999年之前平稳上升,之后又呈现缓慢下降趋势。影响湖北省耕地综合质量变化的主导因子是耕地的经济质量与生态质量的波动,这与不同时期湖北省社会经济与资源环境发展的侧重有关,而耕地的本底质量变化对耕地综合质量变化的影响较小。研究采用的综合指数法能较全面地体现区域耕地质量变化的综合特点,且能反映区域耕地质量变化的一般过程。     

Quantum dots enhance Cu2+-induced hepatic L02 cells toxicity

As a new class of xenogenous nanoparticle,quantum dots (QDs) possess the potential to co-exist with Cu2+ in human liver.The combined toxicity is thus concerned.Considering QDs and Cu2+ are known ROS (reactive oxygen species) inducer,we investigated the combined oxidative stress and corresponding protective strategy using human hepatic L02 cells.The results demonstrated that the presence of a small amount of MPA-CdTe QDs (2 μg/mL) in a Cu2+ solution (2.5-20 μg/mL) resulted in a higher toxicity with up to 8-fold cell viability decrease,which was accompanied by cell morphology changes.The combined toxicity was then confirmed as ROS associated oxidative stress with up to 300% and 35% increase of the intracellular ROS level and glutathione S-transferase (GST) activity,respectively.N-acetylcysteine (NAC) can also provide almost complete protection against the induced toxicity.Therefore,the ROS associated oxidant injury might be responsible for the QDs-Cu2+/Cu2+ induced toxicity and could be balanced through cytoprotective antioxidant enzyme GST.     

Organic matter extracted from activated sludge with ammonium hydroxide and its characterization

In order to characterize the organic properties of waste activated sludge in a wastewater treatment plant,organic matter within sludge was extracted with NH 3 ·H 2 O preferentially,and subsequently fractionated into five fractions using XAD-8/XAD-4 resins.Up to a 63.8%-71.1% of organic matter within the sludge could be efficiently extracted by NH 3 ·H 2 O.Fractionation results showed that hydrophobic acid and hydrophilic fraction were two main components among the sludge organic matter (accounting for 32.2% and 48.0% of the bulk organic matter,respectively),whereas transphilic acid,hydrophobic neutral and transphilic neutral were quite low (accounting for 9.2%,5.8% and 4.8%,respectively).Despite that the extractant of NH 3 ·H 2 O showed a relatively higher extraction efficiency of the aromatic components,the relatively low aromaticity of the organic fractions implied that those non-aromatic components could also be effectively extracted,especially for neutral and hydrophilic fractions.In addition,acidic fractions contained more aromatic humic-like components,whereas the neutral fractions had a greater content of aromatic proteins and soluble microbial byproduct-like components.Extraction of sludge organics with NH 3 ·H 2 O and subsequential fractionation using XAD resins could be a novel method for further characterization of sludge organics.     

Fractionation of heavy metals in shallow marine sediments from Jinzhou Bay, China

This work investigated the distribution and speciation of Cd, Cu, Pb, Fe and Mn in the shallow sediments of Jinzhou Bay, Northeast China, which has been heavily contaminated by nonferrous smelting activities. The concentrations of Cd, Cu and Pb in sediments were found to be 100, 13 and 7 times, respectively, being higher than the national guideline (GB 18668-2002). Sequential extraction test showed that 39%-61% of Cd were exchangeable fractions, indicating that Cd in the sediments posed a high risk to local...     

Iron-doped Mn-Ce/TiO2 catalyst for low temperature selective catalytic reduction of NO with NH3

The catalysts of iron-doped Mn-Ce/TiO 2(Fe-Mn-Ce/TiO 2) prepared by sol-gel method were investigated for low temperature selective catalytic reduction(SCR) of NO with NH 3.It was found that the NO conversion over Fe-Mn-Ce/TiO 2 was obviously improved after iron doping compared with that over Mn-Ce/TiO 2.Fe-Mn-Ce/TiO 2 with the molar ratio of Fe/Ti = 0.1 exhibited the highest activity.The results showed that 96.8% NO conversion was obtained over Fe(0.1)-Mn-Ce/TiO 2 at 180°C at a space velocity of 50,000 hr 1.Fe-Mn-Ce/TiO 2 exhibited much higher resistance to H 2 O and SO 2 than that of Mn-Ce/TiO 2.The properties of the catalysts were characterized using X-ray diffraction(XRD),N 2 adsorption,temperature programmed desorption(NH 3-TPD and NOx-TPD),and Xray photoelectron spectroscopy(XPS) techniques.BET,NH3-TPD and NOx-TPD results showed that the specific surface area and NH3 and NOx adsorption capacity of the catalysts increased with iron doping.It was known from XPS analysis that iron valence state on the surface of the catalysts were in Fe3+ state.The doping of iron enhanced the dispersion and oxidation state of Mn and Ce on the surface of the catalysts.The oxygen concentrations on the surface of the catalysts were found to increase after iron doping.Fe-Mn-Ce/TiO2 represented a promising catalyst for low temperature SCR of NO with NH3 in the presence of H2 O and SO2.     

Removal of humic acid from aqueous solution by cetylpyridinium bromide modified zeolite

Natural zeolite was modified by loading cetylpyridinium bromide (CPB) to create more e cient sites for humic acid (HA) adsorption. The natural and CPB modified zeolites were characterized with X-ray di raction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and elemental analysis. The e ects of various experimental parameters such as contact time, initial HA concentration, solution pH and coexistent Ca2+, upon HA adsorption onto CPB modified zeolites were evaluated. The results showed that natural zeolite had negligible a nity for HA in aqueous solutions, but CPB modified zeolites exhibited high adsorption e ciency for HA. A higher CPB loading on natural zeolites exhibited a larger HA adsorption capacity. Acidic pH and coexistent Ca2+ were proved to be favorable for HA adsorption onto CPB modified zeolite. The kinetic process was well described by pseudo second-order model. The experimental isotherm data fitted well to Langmuir and Sips models. The maximum monolayer adsorption capacity of CPB modified zeolite with surfactant bilayer coverage was found to be 92.0 mg/g.     

微囊藻毒素-LR的臭氧降解研究

采用不同的臭氧投加量,考察了微囊藻毒素-LR(MC-LR)的降解效果,并通过对臭氧氧化过程中产生的8种主要降解产物的相对分子质量分析,推测其降解途径.结果表明,臭氧氧化降解MC-LR主要通过Adda途径和Mdha途径来完成对MC-LR的降解和脱毒作用.臭氧氧化的Adda途径是通过对MC-LR上Adda侧链的进攻,断开具有活性的Adda支链,而达到脱毒的目的;臭氧氧化的Mdha途径是通过对MCs肽环上面Mdha和Ala的断键,打开环状肽链,使藻毒素失去活性,在整个过程中Adda途径占主导地位.在O3∶MC为6时,MC-LR的去除率最高可达到92%.     

V2O5/CeO2催化剂用于低温NH3-SCR的性能研究

采用浸渍法制备了系列V2O5/CeO2催化剂,用于低温NH3选择性催化还原(NH3-SCR)NO.同时,考察了催化剂中V2O5负载量和煅烧温度对催化活性的影响,并运用SEM,BET和XRD物理化学技术对催化剂进行了表征.结果表明,V2O5/CeO2催化剂对模拟烟气中的NO转化呈现出较高的活性,但是V2O5负载量和催化剂的催化活性并不呈线性递增的关系.当V2O5负载量超过10%时,催化剂的催化活性开始下降.随着煅烧温度的升高,由于钒酸铈的生成,催化剂的催化活性下降.400℃为最佳煅烧温度.     

应对大型油罐特大火灾的研究——LASTFIRE项目组简介

简要介绍了LASTFIRE项目组的成立背景、组织结构、研究领域、研究目的、研究思路、研究进展等内容,总结了该项目组近几年的研究成果,指出我国的相关企业或研究机构应积极参与这种国际研究组织,实现研究国外资源共享,共同提高大型储罐的安全技术和管理水平。