Rapid degradation of hexachlorobenzene by micron Ag/Fe bimetal particles

The feasibility of the rapid degradation of hexachlorobenzene (HCB) by micron-size silver (Ag)/iron (Fe) particles was investigated.Ag/Fe particles with different ratios (0,0.05%,0.09%,0.20%,and 0.45%) were prepared by electroless silver plating on 300 mesh Fe powder,and were used to degrade HCB at different pH values and temperatures.The dechlorination ability of Fe greatly increased with small Ag addition,whereas too much added Ag would cover the Fe surface and reduce the effective reaction surface,thereby decreasing the extent of dechlorination.The optimal Ag/Fe ratio was 0.09%.Tafel polarization curves showed that HCB was rapidly degraded at neutral or acidic pH,whereas low pH levels severely intensified H2 production,which consumed the reducing electrons needed for the HCB degradation.HCB degradation was more sensitive to temperature than pH.The rate constant of HCB dechlorination was 0.452 min-1 at 85℃,50 times higher than that at 31℃.HCB was degraded in a successive dechlorination pathway,yielding the main products 1,2,4,5-tetrachlorobenzene and 1,2,4-trichlorobenzene within 2 hr.     

铁炭微电解-微波激发无极紫外光处理活性红195染料模拟废水

以NaClO为氧化剂,采用铁炭微电解-微波激发无极紫外光协同作用处理活性红195染料模拟废水。实验的优化工艺条件为：当NaClO加入量为9mL／L,用铁炭微电解～微波激发无极紫外光协同作用处理质量浓度为400mg／L的活性红195染料模拟废水50min时,废水脱色率达97％,COD去除率达82％。     

转小鼠金属硫蛋白-I基因聚球藻7002对重金属耐受性的研究

研究了野生和转小鼠金属硫蛋白-I(mMT-I)基因聚球藻7002对Pb、Hg、Cd、Mg、Ni、Cu、Co、Zn和As 9种重金属元素的耐受性,以及重金属对藻细胞生长的半抑制浓度(IC50),并与相关文献进行了比较,旨在为转基因藻的工业应用提供依据.结果表明:转mMT-I基因聚球藻7002每单位OD750最高可耐受4～5 mmol/L的Pb2 、0.4～0.6 mmol/L的Cd2 和0.8～1.2mmol/L的Hg2 ,耐受性系数分别为1712.4～2140.5、92.9～139.4、331.6～497.3 mg/g;相比野生聚球藻7002,它对Pb2 、Cd2 的耐受性提高了4～5倍,对Hg2 的耐受性提高了100倍左右.野生聚球藻7002的重金属耐受性系数(mg/g)大小依次为:As(Ⅲ)>Pb2 >Mg2 >Zn2 >Cu2 >Ni2 >Cd2 >Co2 >Hg2 ,而转mMT-I基因聚球藻7002的重金属耐受性系数(mg/g)大小依次为:As(Ⅲ)>Mg2 >Pb2 >Hg2 >Zn2 >Cu2 >Cd2 >Ni2 >Co2 .转mMT-I基因聚球藻7002在重金属溶液中生长的IC50明显大于野生聚球藻7002和其他藻,其对Pb2 、Cd2 和Hg2 的IC50分别为96.60(72 h)、3.94(72h)、7.57(96 h)mg/L.     

双室和单室微生物燃料电池的研究及比较

微生物燃料电池(MFC)可分为双室和单室燃料电池.简述了双室和单室MFC的工作机制,综述了双室MFC中阳极(材料)、阴极(材料)、分割材料和单室MFC中"二合一"、"三合一"型以及无膜型电池的特点,比较并分析了双室和单室MFC在构型上的优缺点,以及两者在内阻、功率密度和库仑效率等方面产生差异的原因,展望了MFC的发展前景.     

华南退化草坡自然恢复中物种多度分布的动态与模拟

华南地区退化草坡自然恢复过程中物种多度格局的动态及其模拟,尚缺乏较为系统的研究.文章探讨是否不同演替阶段群落适合不同的种多度模型,是否存在一个最佳模型以揭示演替过程中群落结构的某些内在数量特征;还要推导多个模型的尺度转换形式.为此,在地处南亚热带的鹤山退化草坡选取处于不同演替阶段的2个典型群落样地,分木本层和草本层调查每个维管植物种的多度;且选择7个具有不同函数形式和广泛代表性的种多度模型,均在倍程(即log2)尺度下拟合数据,运用卡方检验和调整决定系数评估各个模型的适合性.结果表明:(1)7个模型的适合性顺序为:对数柯西＞对数双曲正割＞对数正态＞对数级数＞生态位优先占领＞断棒＞重叠生态位,其中对数柯西适合全部数据,重叠生态位则全部不适合;(2)各模型适合与否和演替阶段无关;(3)左截断对数柯西模型预测的种多度分布显示,随着群落演替,上层(木本层)罕见种比例减少、常见种比例增多,下层(草本层)则相反,这与实际相符.对数柯西分布具有普适性,能最好地反映退化草坡自然恢复中种多度分布的格局与动态.     

Distribution and partition of polycyclic aromatic hydrocarbon in surface water of the Pearl River Estuary, South China

Water samples were collected in the Pearl River Estuary in July 2002 and April 2003. The particulate and dissolved phase polycyclic aromatic hydrocarbons (PAHs) were determined. Total PAH concentrations in water samples were higher in April of 2003 (C (p): 4.0-39.1 ng/L or 445.1-1,089.9 ng/g; C (w): 15.9-184.2 ng/L) than in July of 2002 (C (p): 2.6-26.6 ng/L or 297.7-1,336.6 ng/g; C (w): 12.9-28.3 ng/L). It was found that 5, 6-ring PAHs enrich in the inner estuary samples and so did 3-ring PAHs in the July samples. Compositional differences in the suspended particulate matter (SPM) might be responsible for this observation. The partition coefficient (K (p)) increased with the increasing of the particular organic carbon content of suspended particles as well as the salinity of water, decreased with the increase of the total suspended particles content of samples. A linear correlation between logK (OC) and logK (OW) was found in two sampling periods. The observed values of logK (OC) exceed their predicted values derived form linear free energy relationship between logK (oc) and logK (ow), which could be attributed to the nonlinear sorption of soot-like carbons in suspended particles.     

Integrating multiple vegetation indices via an artificial neural network model for estimating the leaf chlorophyll content of <Emphasis Type="Italic">Spartina alterniflora</Emphasis> under interspecies competition

The invasive species Spartina alterniflora and native species Phragmites australis display a significant co-occurrence zonation pattern and this co-exist region exerts most competitive situations between these two species, competing for the limited space, directly influencing the co-exist distribution in the future. However, these two species have different growth ratios in this area, which increase the difficulty to detect the distribution situation directly by remote sensing. As chlorophyll content is a key indicator of plant growth and physiological status, the objective of this study was to reduce the effect of interspecies competition when estimating Cab content; we evaluated 79 published representative indices to determine the optimal indices for estimating the chlorophyll a and b (Cab) content. After performing a sensitivity analysis for all 79 spectral indices, five spectral indices were selected and integrated using an artificial neural network (ANN) to estimate the Cab content of different competition ratios: the Gitelson ratio green index, the transformed chlorophyll absorption ratio index/optimized soil-adjusted vegetation index, the modified normalized difference vegetation index, the chlorophyll fluorescence index, and the Vogelmann chlorophyll index. The ANN method yielded better results (R ² = 0.7110 and RMSE = 8.3829 μg cm^?2) on average than the best single spectral index (R ² = 0.6319 and RMSE = 9.3535 μg cm^?2), representing an increase of 10.78% in R ² and a decrease of 10.38% in RMSE. Our results indicated that integrating multiple vegetation indices with an ANN can alleviate the impact of interspecies competition and achieve higher estimation accuracy than the traditional approach using a single index.     

广州市环境空气监测与预警体系在亚运会中的应用

本文以2010年广州亚运会空气质量监测保障为例,从广州市环境空气质量监测网络、空气质量预报、预警体系和环境质量会商及信息发布管理机制等方面,介绍了广州市环境空气监测与预警体系。通过2010年广州亚运会空气质量保障监测实践,证明广州市环境空气监测与预警体系是适应广州环境保护工作发展,并能满足特殊环境空气质量保障目标需求,具有示范作用和可供全国中心城市借鉴的先进的环境空气质量监测与预警体系。     

应用海相镜质组反射率研究华北地区下古生界成熟度

如何评价下古生界高－过成熟海相碳酸盐岩成熟度是当前急需解决的问题。笔者通过对华北地区下古生界海相烃源岩的有机岩石学分析，确认下古生界高－过成熟碳酸盐岩中普遍存在海相镜质体，建立了海相镜质体反射率与镜质组反射率之间的关系。     

人粪便序批式好氧堆肥热平衡分析

利用以锯末为载体的Bio—LuxS15型生态卫生设备,进行人粪便连续堆肥试验。在90天的试验周期内,每天定时定量投加1kg粪便,分析了系统的输入热量与输出热量组成和热量平衡。试验结果表明,水蒸发速率随着反应时间而增加,其值在1．1kg／d～5．1kg／d的范围内。反应器温度维持在50℃～60℃时下,输入热量的77．2％-99．5％主要用来进行水分的蒸发,在保证堆肥反应器中含水率维持在50％-60％的前提下,减少多余水分可有效减少热量消耗。整个过程无臭无味,通过外加热源,可以保证高含水率粪便堆肥化顺利的进行。