Particle-size-fractioned transfer of dioxins from sediments to water columns by resuspension process

Particle-size-fractioned transfer of dioxins from sediments to water columns by resuspension process was investigated, using supernatant samples obtained from shaking experiments of sediment-water pairs simulating natural disturbances. The concentrations (dry-matter mass basis) of individual compounds (Cfraction) in two particle size fractions (0.1-1 and 1-10 μm) in the supernatants were generally slightly higher than those in the original sediment (Csed). Cfraction/Csed ratios ranged from 0.45 to 5.9 (median 1.5) without consistent differences among congener groups or consistent correlations against the number of chlorine atoms. The dioxin concentrations in the water column associated with the remaining sediment particles can therefore be estimated by those in the original sediment and by the concentration of suspended sediment particles in the water. The concentration of each compound in the remaining sediment particles (mostly 0.1-10 μm in size) can be roughly estimated by multiplying the concentration in the original sediment by 1.5.     

垃圾填埋场微生物气溶胶粒径分布研究

为了了解垃圾填埋场微生物气溶胶粒径分布规律,在北京市某垃圾卫生填埋场填埋区、渗滤液处理区、生活区分别选定监测点,利用安德森六级微生物采样器,对填埋场空气微生物进行了系统的定点取样、测定和分析。研究结果表明,空气细菌粒径分布均为第Ⅰ级(>8.2 μm)最高,填埋区空气细菌粒径呈偏态分布,渗滤液处理区、生活区分别在第Ⅳ级和第Ⅲ级出现第2个峰值。携带细菌的可吸入微粒在渗滤液处理区比例最大。空气真菌与放线菌均在第Ⅳ级分布最高,携带真菌和放线菌的可吸入粒子的比例显著大于细菌(P<0.05)。填埋区不同作业时段空气微生物粒径在各级分布比例基本一致。填埋区细菌气溶胶中值直径为5.7 μm,渗滤液处理区为3.7 μm,生活区为5.3 μm,显著大于真菌气溶胶和放线菌气溶胶的中值直径(P<0.05)。     

粒径对镁粉爆炸特性的影响

在简要分析了镁粉爆炸的过程和特性基础上,结合在20 L球型爆炸测试装置中对粒径D50为6,47,104,173 μm镁粉的爆炸特性实验数据,着重分析了粒径对镁粉爆炸特性所产生的影响.实验结果表明,随着粒径的增大,镁粉的爆炸危险性随之减小.     

Extraction of labile metals from solid media by dilute hydrochloric acid

Extraction of labile metals from solid media is environmentally more meaningful than a total digestion. A variety of reagents have been introduced in the literature, but dilute HCl has received the greatest attention. We compare metal concentrations liberated by a dilute HCl leach with the sum of the 3-step optimized (standardized) BCR sequential extraction procedure. This is the first study to compare these procedures over a range of grain sizes. Road-deposited sediments from 10 sites in Honolulu were fractionated into six grain size classes. Aliquots of individual fractions were digested with dilute HCl, the 3-step BCR procedure (‘labile’), and a 4-acid (total) procedure. Results indicated that the weighted labile concentrations of Al, Cu, Fe, Mn, Ni, Pb and Zn were statistically greater than those from the dilute HCl leach. However, regression analysis indicated strong statistically significant relationships between the two partial extraction procedures for all metals. On a whole-sample basis, the toxicity classifications for anthropogenic-enhanced metals (Cu, Pb and Zn) were similar between extractions. Taken together, results suggest that the application of dilute HCl to solid media provides a rapid, cost-effective, and environmentally meaningful approach for contaminant monitoring.     

全工班呼吸性粉尘测定及防尘措施研究

针对呼吸性粉尘对矿井工人身体健康的危害,对煤矿综采工作面、综掘工作面、炮掘工作面等进行分工种个体性的全尘和呼尘监测,测定了各工作面粉尘(全尘和呼尘)的浓度、粉尘分散度和SiO2浓度。其结果表明:全工班呼吸性粉尘测定的方法更加真实可靠,更真实地反映了呼吸性粉尘对井下各操作工种的致病危害,测得的各工作面各工种的呼尘浓度均高于国家标准。通过数据的分析以及工人的建议,提出了一些新式的、有效的防尘措施来降低呼吸性粉尘对人体健康的危害。     

Co3O4/介孔分子筛催化剂对苯催化完全氧化的研究

分别以介孔分子筛MCM-41、MCM-48、SBA-15为载体,采用等体积浸渍法制备了氧化钴/介孔分子筛催化剂,利用N₂吸附、X射线衍射、程序升温还原等技术对催化剂进行了表征,考察了Co₃O₄的负载量及载体的孔结构对催化剂完全催化氧化苯的性能的影响。结果表明,Co₃O₄的负载量为20%时,催化剂的催化活性最好;载体的孔径和催化剂的可还原性能是影响催化活性的主要因素,催化剂活性顺序为Co₃O₄ /SBA-15> Co₃O₄ /MCM41> Co₃O₄ /MCM-48。     

气相分子吸收光谱法测定地表水中硫化物

采用气相分子吸收光谱法测定地表水中硫化物,方法检出限为0.002 mg/L,水样加标回收率为96.5%~107%,精密度(RSD,n=6)为0.08%~1.38%。实验结果表明:该方法准确可靠、灵敏度好、操作简便,适用于地表水中硫化物分析要求。     

气相分子吸收光谱法测定印染废水中氨氮的影响因素

采用气相分子吸收法光谱测定印染废水中的氨氮,并对相关影响因素进行探讨。结果证实,硫化物和尿素会对氨氮的测定产生负干扰,硫化物干扰可用乙酸锌-乙酸钠固定液沉淀法去除,尿素干扰可以用稀释法去除,但仅适用于氨氮质量浓度0.10 mg/L且稀释后尿素质量浓度≤100 mg/L的水样;苯胺、浊度和色度对测定无干扰,可直接检测。     

北京城区冬季道路灰尘粒度特征分析

对2013年1月于北京城区采集的40组道路灰尘样品用激光粒度仪进行粒度测定。结果表明:北京城区冬季道路灰尘频率曲线呈单峰态或双峰态分布,单峰型峰值粒径为112~237μm,双峰型第一峰值粒径为189~286μm,第二峰值粒径为42~57μm。道路灰尘平均粒径为183μm,分选性差,呈极不对称的极正偏宽峰态到窄峰态,属砂土。道路灰尘是局地灰尘和区域灰尘的混合物,且主要为跃移或短时悬浮颗粒物,对大气悬浮颗粒污染物的贡献量不大。研究4种不同道路类型灰尘发现,平均粒径从大到小顺序为快速路支路次干路主干路,分选系数与偏度为快速路主干路次干路支路,峰度无较大区别,细颗粒含量主干路次干路(支路、快速路)。主干路灰尘污染贡献率更高,对大气环境和人体健康的危害潜力不容忽视。     

分子筛生产废水中悬浮物的絮凝与回用

对分子筛生产废水进行了絮凝沉降分离试验，确定了絮凝剂、助凝剂及絮凝敢分离条件。试验结果表明，絮凝沉降所得到的絮凝物料的化学组成、结构、性能与絮凝前原废水中的悬浮物基本一致，可返回原生产工序中使用。