用混合二元酸制备混合酸二甲酯

以工业副产物混合二元酸（DBA）和甲醇为原料,用自制PW12／SiO2作催化剂制备混合酸二甲酯（DME）,确定了最佳制备条件：甲醇与DBA摩尔比为3．5,PW12／SiO2加入量（PW12／SiO2中PW12占DBA的质量分数）为2％,反应时间为4．5h,100gDBA中甲苯加入量为50mL。在此最佳条件下,DME收率为84．7％,所得DME为无色澄清液体,其中丁二酸二甲酯的质量分数为11．03％,戊二酸二甲酯的质量分数为13．88％,己二酸二甲酯的质量分数为73．79％。PW12／SiO2具有较好的稳定性和一定的重复使用性,PW12／SiO2重复使用5次时的DME收率仍大于70％。     

Polychlorinated biphenyl residues in sandstorm depositions in Beijing, China

Sandstorms, which distribute many particles, are a special atmospheric occurrence and are frequent in northern China. We conducted this study to determine, for the first time, the concentration of polychlorinated biphenyls (PCBs) in sandstorm depositions. We collected 13 samples from urban areas of Beijing, and we measured a total of 144 PCB congeners. Thirteen samples all contained PCB residues. The total PCB concentration ranged from 1.6 to 15.6ngg(-1) (median, 4.8ngg(-1), dry weight), with trichlorinated biphenyls as the predominant homologue (>50.4%). Furthermore, we observed increasing PCB contamination from northwest to east Beijing. We later explored possible factors affecting contamination of the sandstorm depositions, which revealed a significant correlation between SigmaPCBs and the minimum particle size of the sandstorm deposition samples. Principal-component analysis revealed that the major source of PCBs in Beijing may be potentially associated with the number-one commercial PCB through the long-range transmission. In previous results, PCBs were not a severe component of contamination in sandstorm depositions of Beijing. However, this study suggested that sandstorm deposition may be a potential source of exposure to PCBs for the residents of Beijing, China.     

内蒙古阴山北麓地区可持续发展问题研究

本文在分析内蒙古阴山北麓地区生态环境恶同状及其形成原因的基础上,提出了以建立一机制为主的实现可持续发展对策。     

Seedling Biomass Partition and Water Use Efficiency of Switchgrass and Milkvetch in Monocultures and Mixtures in Response to Various Water Availabilities

Seedling biomass and allocation, transpiration water use efficiency (TWUE), and species competition between switchgrass (Panicum virgatum L.) and milkvetch (Astragalus adsurgens Pall.) were investigated in a pot-cultivated experiment under different levels of water availability. The experiment was conducted using a simple replacement design in which switchgrass and milkvetch were grown in growth chamber with ten seedlings per pot, in three combinations of the two species (0:10, 5:5 and 10:0). Five water treatments included sufficient water supply (HW), gradual soil drying from HW (DHW), moderate water stress (LW), gradual soil drying from LW (DLW), and re-establishment of LW conditions after 12 days of drying from LW (RLW). Water treatments were applied over a 15-day period. Biomass production and its partitioning, and TWUE were determined at the end of the experiment. Species competitive indices (competitive ratio (CR), aggressivity (A) and relative yield total (RYT)) were calculated from the biomass dry weight data for shoots, roots and total biomass. Water stress significantly reduced seedling biomass production but increased root:shoot ratios in both monocultures and mixtures. In the RLW treatment, only switchgrass monocultures displayed compensatory biomass production and TWUE, while both species demonstrated compensatory growth in the mixture. Switchgrass was the dominant species and much more aggressive than milkvetch in the LW treatment, while in the other four treatments milkvetch was the dominant species as measured by the positive value of aggressivity and higher values of CR. The total biomass RYT values of the two species were higher than 1.0, indicating some degree of resource complimentarity. In the two-species mixture, although the biomass production was lower than that of milkvetch in the monoculture, there was better TWUE, especially under low and fluctuating water availability.     

Heavy metal in sediments of Ziya River in northern China: distribution,potential risks,and source apportionment

The concentration partitioning between the sediment particle and the interstitial water phase plays an important role in controlling the toxicity of heavy metals in aquatic systems. The aim of this study was to assess the sediment quality in a polluted area of the Ziya River, Northern China. The contamination potential and bioavailability of six metals were determined from the concentrations of total metals and the bioavailable fractions. The results showed that the concentrations of Cr, Cu, Ni, Zn, and Pb exceeded the probable effect concentration at several sites. The high geoaccumulation indices showed that the sediments were seriously contaminated by Cd. The ratio of acid-volatile sulfide (AVS) to simultaneously extracted metal (SEM) was higher than 1, which indicated that the availability of metals in sediments was low. The risk assessment of interstitial waters confirmed that there was little chance of release of metals associated with acid-volatile sulfide into the water column. Values of the interstitial water criteria toxicity unit indicated that none of the concentrations of the studied metals exceeded the corresponding water quality thresholds of the US Environmental Protection Agency. Positive matrix factorization showed that the major sources of metals were related to anthropogenic activities. Further, if assessments are based on total heavy metal concentrations, the toxicity of heavy metals in sediment may be overestimated.     

镁盐和炉渣对印染废水的脱色处理

实验研究了不同pH、温度：Mg2＋投量和沉降时间下,镁盐、炉渣、镁盐＋炉渣3种处理对模拟和实际印染废水的脱色效果。结果表明,在pH为11～11．5、沉降30rain、30℃及Mg2＋投加量为500～600mg／L的最优脱色条件下,3种处理对艳红FXC模拟废水的最大脱色率分别为98．41％、98．43％和99．37％,对实际印染废水的最大脱色率分别为90．18％、89．63％和93．33％,其中,镁盐＋炉渣脱色效果最好,这可能与炉渣吸附和起到协同增强Mg（OH）2沉淀效果的作用有关。对水样的液相色谱初步检测分析表明,实际废水脱色处理前后染色基团峰高和种类发生了变化。该研究对盐田富镁卤水和炉渣等废物的资源化开发有重要参考价值。     

镁盐和炉渣对印染废水的脱色处理简

实验研究了不同pH、温度、Mg²⁺投量和沉降时间下,镁盐、炉渣、镁盐+炉渣3种处理对模拟和实际印染废水的脱色效果。结果表明,在pH为11~11.5、沉降30 min、30℃及Mg²⁺投加量为500~600 mg/L的最优脱色条件下,3种处理对艳红FXC模拟废水的最大脱色率分别为98.41%、98.43%和99.37%,对实际印染废水的最大脱色率分别为90.18%、89.63%和93.33%,其中,镁盐+炉渣脱色效果最好,这可能与炉渣吸附和起到协同增强Mg（OH）₂沉淀效果的作用有关。对水样的液相色谱初步检测分析表明,实际废水脱色处理前后染色基团峰高和种类发生了变化。该研究对盐田富镁卤水和炉渣等废物的资源化开发有重要参考价值。     

辽东湾浮游植物多样性及与海洋环境因子的关系

以2005年7～9月份辽东湾浮游植物的调查数据为主,结合以往的调查数据对浮游植物的种群结构、分布特征、多样性指数的变化及其与海洋环境因子的关系进行了分析.结果表明,浮游植物个体数量高值区主要集中在北部海区,而其生物多样性与均匀度指数却明显低于西部和东南部海区,说明该海区水体、生态环境、生物群落不如西部和东南部海区稳定、成熟.浮游植物多样性主要受水温、盐度、COD、生物量、物种数等环境因子的制约.     

洲际码头公司储罐火灾事故分析

针对洲际码头公司储罐火灾事故,通过时间序列法和事件树分析法对事故进行分析,梳理事故发展过程,对事故发生时及事故过程中存在的问题进行分析总结,得到事故的直接原因、间接原因,以及事故发生过程中的关键节点;针对事故发生过程中的关键节点,增加安全检测和智能化设备,建立新的事件树进行分析,发现安全水平得到有效提高;结合罐区未来发展趋势,并针对我国石油制品罐区的安全运行及事故响应提出合理化建议。     

施用超富集植物生物炭对土壤性质及玉米苗期生长的影响

植物提取修复是目前研究较多且极具发展前景的重金属污染土壤治理技术,广泛应用于砷、镉、铜、锌等重金属污染土壤的修复。然而,植物提取土壤重金属后产生大量植物残体的处置成为目前环境治理的难点。本研究通过将超富集植物伴矿景天和苎麻收割后制备成生物炭(350℃)进行盆栽实验,观测了超富集植物生物炭对玉米生长的影响,评估了超富集植物炭化处理的可行性。结果显示：添加苎麻生物炭(ZM)可以显著减少玉米地上部氮磷含量,但对生物量、光合等指标无显著影响,同时玉米地上及地下部分重金属Zn、Cd含量稍有增加;而添加景天生物炭处理(JT)玉米的总生物量相比对照降低了44.4%,蒸腾速率等光合参数也显著低于对照处理,根体积、根表面积和总投影面积分别降低了35.1%、28.1%和28.1%,玉米地上部和根部Zn含量为对照的16.0、21.7倍,Cd含量为对照的11.6、25.8倍。结合原材料以及生物炭中Zn、Cd含量分析,其差异主要由苎麻、景天中Zn、Cd含量不同所致,景天和苎麻自身重金属含量是决定其是否可以生物炭化并应用于农田的关键因素。