La-Ce-attapulgite催化分解NO的研究

采用化学共混法制备系列La-Ce-attapulgite催化剂,并在固定床反应器中进行NO催化分解性能测试.实验考察了稀土加入量、La/Ce配比、共混液pH值和催化剂的活化煅烧温度等制备条件对催化剂脱硝性能的影响.结果表明:稀土加入量为2%,共混液pH=7,La/Ce比值为LaxCe(1-x)(x=0.5),煅烧温度4...     

Significance of metal exchange in EDDS-flushing column experiments

Chelating agents have been widely studied for extracting heavy metals from contaminated soils, and the effectiveness of EDDS ([S,S]-ethylene-diamine-disuccinic acid) has aroused extensive attention because of its biodegradability in the natural environment. However, in the course of EDDS-flushing, metal exchange of newly extracted metal-EDDS complexes with other sorbed metals and mineral cations may result in metal re-adsorption on the soil surfaces. Therefore, this study investigated the relative significance of metal exchange under different travel distances of chelant complexes, characteristics of soil contamination, and solution pH in the column experiments. As a result of metal exchange, the elution of Zn and Pb was retarded and the cumulative extraction was lower than those of Ni and Cu, especially over a longer travel distance. Compared with the field-contaminated soils, the effects of metal exchange were even more substantial in the artificially contaminated soil because of a greater amount of extractable metals and a larger proportion of weakly bound fractions. By contrast, metal exchange was insignificant at pH 8, probably due to less adsorption of metal-EDDS complexes. These findings highlight the conditions under which metal exchange of metal-EDDS complexes and the resulting impacts are more significant during EDDS-flushing.     

混凝-活性炭-膜工艺处理黄磷化工渗滤液的研究

采用混凝-活性炭-膜工艺对黄磷化工渗滤液进行处理,重点考察了该工艺对有机物的去除机制.实验结果表明,混凝剂硫酸铝的投加量为0.2g/L时,渗滤液中各污染物去除率较好;颗粒活性炭对渗滤液中有机物的吸附容量几乎不受渗滤液pH的影响,吸附等温线更符合修正的Freundlich模型,拟二级动力学模型能更好地定量描述有机物在颗粒活性炭上的吸附过程;膜处理进一步提高了剩余有机物和其他污染物的去除率.     

结构用钢(16Mn)高温力学性能恒温加载试验研究

文章利用WAW-1000微机控制电液伺服万能试验机对我国五大钢厂的16Mn低合金钢进行了试验研究。通过对100、200、300、400、500、600℃共6个温度水平、77个试件进行恒温加载试验,建立了钢材强度、弹性模量和线膨胀系数随温度的变化规律模型。并与各国方案进行了比较。高温屈服强度的确定采用了更符合材料“屈服”意义的切线交点法。     

湛江市农村居民点用地面积变化及驱动力分析

利用湛江市1996—2005年农村居民点用地面积数据及相关社会经济数据,在分析农村居民点用地面积变化的基础上,采用主成分分析法对其进行了驱动力分析。结果表明,近十年来湛江市农村居民点用地总面积呈逐年上升的趋势,而农村居民点人均用地面积总体呈减少趋势。湛江市农村居民点用地面积增加主要集中在徐闻、吴川和市区。湛江市农村居民点用地面积变化主要受农村人口增长、农村经济发展、农业结构调整、农村交通发展和乡镇企业发展等因素的影响。     

Identification of barley genotypes with low grain Cd accumulation and its interaction with four microelements

The variation in grain cadmium (Cd) concentrations was evaluated among 600 barley genotypes grown in the same field condition to select low Cd accumulating genotypes. The results showed that there is considerable genotypic variation in grain Cd concentrations in barley grain samples, with the mean concentration of 0.16 mg kg(-1) DW and the variation of 0 (not detected) to 1.21 mg kg(-1) DW, and 47.2% of the grain samples exceeded the maximum permissible concentration (MPC) for Cd in cereal grains. In addition, differences between genotypes over the two years were fairly consistent, and Beitalys and Shang 98-128 showed the lowest grain Cd concentration, being 97.5% lower than that in the two highest Cd accumulators E-barley 6 and Zhenong 8 in the second harvest year. The great genotypic differences in Cd concentrations indicated that it is possible to lower Cd content of barley through cultivar selection and breeding for use at sites where Cd concentration in grain exceeds the MPC. Significant genotypic difference was also found in microelement concentrations. Correlation analysis showed that only Mn accumulation is synergetic with Cd accumulation, despite slightly positive relationship between Cd and Zn, Cu, or Fe in accumulation in barley grains.     

Concentrations of pentachlorophenol (PCP) in fish and shrimp in Jiangsu Province, China

Pentachlorophenol (PCP) concentrations were determined in 55 samples of fish, shrimp, crabs, frogs and turtles collected in Jiangsu Province and 55 freshwater shrimp samples collected from the Huiming Fish Market, Nanjing, China between 2003 and 2004. PCP concentrations ranged from less than the method detection limit (MDL: 0.5 microg/kg ww) to 61 microg/kg ww, with a mean of 5.2 microg/kg ww in 55 samples collected across Jiangsu Province and a mean of 0.5 microg/kg ww for freshwater shrimp collected from the Huiming Fish Market. Concentrations of PCP in common carp (Carassius auratus) were significantly greater than concentrations of PCP in other species from all of the areas studied. Grass carp (Ctenopharyngodon idella) contained the second greatest concentrations and crustacean species contained the least concentrations. Concentrations of PCP were greater in samples collected from Southern Jiangsu than those collected from other areas of Jiangsu Province. Concentrations of PCP in the freshwater shrimp (Macrobrachium nipponense) from the Huiming Fish Market were greater in March and September than those collected in June and December. Based on the allowable daily intake (ADI) set by the US National Academy of Science, current concentrations of PCP measured in aquatic products from Jiangsu Province presented minimus health risks to humans.     

S-316提取剂测定水中石油类

红外分光光度法测定水中石油类，可用S－316（六氯四氟丁烷）作提取剂，测定了以S－316为溶剂配制的正十六烷，姥鲛烷和甲苯溶液的校正系数，并对该校正系数作了检验，比较了S－316和CCl4的本底值和萃取率，结果表明S－316可作为红外法测定水中石油类的提取剂，并具有毒性小，萃取率高等特点。     

怠速工况下汽车使用乙醇汽油排放污染物的变化

对怠速工况下使用乙醇汽油汽车尾气中污染物进行了检测.结果表明,使用乙醇汽油后,汽车尾气中CO和HC浓度明显降低,平均下降率为56.9%和38.2%;NOx平均下降率为15.0%;CO2浓度平均增长率为5.04%;苯系物浓度明显降低,平均下降率在45.5%～53.1%;醛类的浓度增加明显,平均增长率在47.8%～293%;丙酮、丁酮的浓度增加,分别为16.6%和25.3%.     

基于健康风险的三氯杀螨醇生产设备表面污染物筛选值推算的初步研究

运用确定性和概率性人体健康风险评估的方法,推算一般工业暴露情景和拆卸清理暴露情景下三氯杀螨醇生产设备表面污染物的筛选值.结果表明:p,p'-滴滴涕、p,p'-滴滴滴和p,p'-滴滴依基于确定性风险评估的设备表面筛选值在一般工业暴露情景下分别为0.224 mg/m2、0.214 mg/m2和0.151 mg/m2,在拆卸...