Relationship between the extractable metals from soils and metals taken up by maize roots and shoots

Two extraction procedures, i.e. a single extraction procedure using low-molecular-weight-organic-acids (LMWOAs) as extractant and a sequential extraction procedure recommended by the European Community Bureau of Reference (BCR), were performed to extract metal fractions from wet rhizosphere soil. And the extracted soil solutions were further fractionated as colloidal and truly dissolved fractions. Heavy metals in maize roots were experimentally defined as metals adsorbed on cell wall and metals taken up by cross-membrane by washing with CaCl(2). The correlation coefficients between extractable metals from soil and taken up by maize roots and shoots were compared between two extraction methods, and a good correlation was obtained if LMWOAs were used. In contrast, the correlation coefficients were poor when the BCR method was used.     

维生素C二步发酵中L-山梨糖脱氢酶的性质及作用

从氧化葡萄糖酸杆菌细胞质中分离纯化出L 山梨糖脱氢酶 (SDH) ,其分子量为 46× 10 3 ,表观分子量为 190× 10 3 ;在测试范围内 ,最适pH是 7.4,温度为 5 5℃ ,最稳定的 pH是 7.0 ,温度为 30℃以下 ;FeCl3 促进酶活 ,CoCl2 抑制酶活 .该酶活力与发酵产物 2 酮基 L 古龙酸的合成呈正相关 ;伴生菌促进产酸菌生长和代谢 ,并使该酶比活力增加 ,从而提高发酵系统中该酶的总活力 .图 11表 5参 9     

不同源胡敏酸的表征及其对磺胺嘧啶光降解的影响

以国际腐殖酸协会(IHSS)推荐的方法为基础,对四川省绵阳市青义镇泥炭地、水稻田及凋落物覆盖土层中的胡敏酸(HA)进行提取纯化.通过元素组成、紫外-可见光谱、傅里叶红外光谱及三维荧光光谱对各HA样品的结构特性进行对比分析,并探讨各HA对磺胺嘧啶光降解行为的影响.结果表明:泥炭地HA(NTHA)、水稻田HA(SDHA)、凋落物覆盖土HA(LYHA)及市售商品HA(SPHA)均主要由C、H、O、N 4种元素构成,芳香性大小为SPHANTHALYHASDHA;与提取的HA相比,SPHA含有更多的含氮类、芳香类、脂类化合物及含氧官能团,腐殖化程度高,可能含有较多的光活性基团;磺胺嘧啶(SDZ)在黑暗条件下表现出良好的稳定性,而紫外光照条件下发生了缓慢降解,光降解过程符合一级反应动力学;添加不同来源HA后,各体系SDZ的光降解速率均大于纯水溶液,且HA表现出的促进作用大小为SPHASDHANTHALYHA,这可能与各HA的腐殖化程度相关.     

Air pollution and inhalation exposure to particulate matter of different sizes in rural households using improved stoves in central China

Household air pollution is considered to be among the top environmental risks in China.To examine the performance of improved stoves for reduction of indoor particulate matter(PM) emission and exposure in rural households, individual inhalation exposure to size-resolved PM was investigated using personal portable samplers carried by residents using wood gasifier stoves or improved coal stoves in a rural county in Central China.Concentrations of PM with different sizes in stationary indoor and outdoor air were also monitored at paired sites. The stationary concentrations of size-resolved PM in indoor air were greater than those in outdoor air, especially finer particles PM0.25. The daily averaged exposure concentrations of PM0.25, PM1.0, PM2.5 and total suspended particle for all the surveyed residents were 74.4 ± 41.1, 159.3 ± 74.3, 176.7 ± 78.1 and 217.9 ± 78.1 μg/m3,respectively. Even using the improved stoves, the individual exposure to indoor PM far exceeded the air quality guideline by WHO at 25 μg/m3. Submicron particles PM1.0 were the dominant PM fraction for personal exposure and indoor and outdoor air. Personal exposure exhibited a closer correlation with indoor PM concentrations than that for outdoor concentrations. Both inhalation exposure and indoor air PM concentrations in the rural households with gasifier firewood stoves were evidently lower than the reported results using traditional firewood stoves. However, local governments in the studied rural areas should exercise caution when widely and hastily promoting gasifier firewood stoves in place of improved coal stoves, due to the higher PM levels in indoor and outdoor air and personal inhaled exposure.     

Thermal energy storage and thermodynamic properties of (E)-3-m-tolylbut-2-enoic acid as a medium temperature phase change material

Phase change materials (PCMs) that can store and release heat energy over the temperature range from 363 to 393 K are crucial for solar absorption cooling, and it is worthy to seek new solid-liquid PCMs candidates that melt and crystallize in this temperature range. In this paper, (E)-3-m-tolylbut-2-enoic acid (mTBEA) was applied as a PCM candidate. Its thermal energy storage properties and thermal stability were systematically investigated. The results showed that mTBEA melted at 382.9 ± 0.5 K and crystallized at about 364 K, with a melting enthalpy (Δ_fusH) of 138.4 ± 6.9 J g^?1 and showed good long-term cyclic stability and thermal stability. The supercooling of mTBEA was stabilized at about 20 K, indicating that the conservation condition of melted mTBEA could be simple. In addition, the melted mTBEA could release all the absorbed thermal energy upon crystallizing. Besides, mTBEA exhibited good thermal stability for it to be applied as PCM. Hence, mTBEA is a promising PCM candidate for solar absorption cooling. Furthermore, the heat capacity of mTBEA was measured by modulated temperature differential scanning calorimetry (MTDSC) over the temperature range from 198.15 to 431.15 K, and the molar thermodynamic functions, [H_T-H_298.15]_m and [S_T-S_298.15]_m, were calculated based on the fitted molar heat capacity data.     

Human bronchial epithelial cell injuries induced by fine particulate matter from sandstorm and non-sandstorm periods: Association with particle constituents

Epidemiological studies have demonstrated the exacerbation of respiratory diseases following sandstorm-derived particulate matter(PM) exposure.The presence of anthropogenic and biological agents on the sandstorm PM and the escalation of PM 2.5 μm(PM2.5)pollution in China have led to serious concerns regarding the health effects of PM2.5during Asian sandstorms.We investigated how changes in PM2.5composition,as the weather transitioned towards a sandstorm,affected human airway epithelial cells.Six PM2.5samples covering two sandstorm events and their respective background and transition periods were collected in Baotou,an industrial city near the Gobi Desert in China.PM samples from all three periods had mild cytotoxicity in human bronchial epithelial cell line BEAS-2B,which was positively correlated with the contents of polycyclic aromatic hydrocarbons and several metals.All PM samples potently increased the release of interleukin-6(IL-6) and interleukin-8(IL-8).Endotoxin in all samples contributed significantly to the IL-6 response,with only a minor effect on IL-8.Cr was positively correlated with both IL-6 and IL-8 release,while Si was only associated with the increase of IL-6.Our study suggests that local agricultural and industrial surroundings in addition to the sandstorm play important roles in the respiratory effects of sandstorm-derived PM.     

论环境标准的创新

文章针对我国环境标准工作的现状，以与时俱进思想，提出改革创新的八个重点。     

粉煤灰干法除炭技术与设备

根据最新收集的文献资料，介绍了国外典型的粉煤灰干法除炭，特别是电选除炭方面的新进展，包括其工作原理、优缺点及工业应用情况。旨在为国内相关企业提供参考。     

杭州湾滨岸潮滩表层沉积物中有机氯农药的分布特征

运用气相色谱-电子捕获(GC-ECD)法对杭州湾滨岸潮滩表层沉积物样品中的有机氯农药(OCPs)进行了定量分析.结果表明,沉积物中有机氯农药(OCPs)总含量在2.38～17.71 ng·g-1(以干重计,下同)之间,其中,六六六类(HCH)农药含量在0·33～8·75 ng·g-1之间,滴滴涕类农药(DDT)含量在0...     

气箱式脉冲袋式除尘器清灰技术

为了深入认识气箱式脉冲袋式除尘器的清灰机理,按可压缩气体绝热状态和等温状态分别计算了脉冲质量流量和气箱中气体压力、密度的变化,进一步推导出穿过滤袋的清灰气流速度方程和清灰剥离力方程.按照在袋式除尘器实验模型上所测定的粉尘剥离率与清灰剥离力之间的特性关系,确定了已知条件下的粉尘剥离率.若预先确定要求达到的粉尘剥离率,可以通过清灰气流速度方程和剥离力方程确定脉冲清灰系统的几何参数、脉冲喷吹压力、脉冲喷吹时间和分室内的过滤面积(或滤袋直径、滤袋长度和滤袋数量等).该理论和实验研究内容为气箱式脉冲袋式除尘器脉冲清灰系统设计计算提供了理论依据.