Atmospheric distribution of particulate- and gas-phase phthalic esters (PAEs) in a Metropolitan City, Nanjing, East China

Phthalic acid esters (PAEs) are used in many branches of industry and are produced in huge amounts throughout the world. An investigation on particulate- and gas-phase distribution of PAEs has been conducted in Nanjing (China). The 12-h daily sampling program (from 8:00 am to 8:00 pm) for ten consecutive days was conducted in April, July and October 2005, and in January 2006 at about 1.5m above the ground level. For comparative purposes, sampling events were simultaneously conducted at two stations, one at the urban center and the other about 12 km from city center for suburban background monitoring. It was observed that the most abundant members of the PAE group were dimethyl phthalate (DMP) (10.1 ng m(-3), average), diethyl phthalate (DEP) (3.4 ng m(-3)), dibutyl phthalate (DBP) (58.8 ng m(-3)), butylbenzyl phthalate (BBP) (3.2 ng m(-3)), di-2-ethylhexyl phthalate (DEHP) (20.3 ng m(-3)) and di-n-octyl phthalate (DOP) (1.2 ng m(-3)). The average contribution of PAEs in the gas phase to the total PAE concentration (Sigma(6)PAE, sum of six PAE congeners) ranged from 75.0% to 89.2%. Both particulate- and gas-phase Sigma(6)PAE concentrations decreased with increasing temperature. Experimentally determined gas-particle partitioning (K(p)) of PAEs is well-correlated with their vapor pressure. The Sigma(6)PAE levels in the urban area are approximately 3.5 times as high as the levels found at the suburban station. The vertical profiles from 1.5 to 30.0m above the ground display slight height dependence.     

Spatial trend and pollution assessment of total mercury and methylmercury pollution in the Pearl River Delta soil, South China

Total mercury (THg) and methylmercury (MeHg) were measured in large number of soil samples collected from areas with different types of land use, different depth in the Pearl River Delta (PRD) of South China. THg and MeHg concentrations ranged from 16.7 to 3320 ng g⁻¹ and 0.01 to 1.34 ng g⁻¹, respectively. THg levels are highest in the top 0-20 cm soil layer, and decrease from the surface to bottom layer soil. Spatial variation was observed with different types of land use. Urban parks had the highest concentrations and the other areas tended to decrease in the order of residential areas, industrial areas, vegetable fields, cereal fields, and woodlands. Temporal variation was also noted, and two relatively high THg contamination zones located in the northwestern part of the PRD have significantly expanded over the last two decades. Both THg and MeHg concentrations were correlated significantly with soil organic matter (OM), but not with soil pH. THg pollution status was evaluated using two assessment methods.     

基于竞争失效的导弹机电产品可靠性评估

目的 解决导弹机电产品退化-突发竞争失效模式下的可靠性评估问题。方法 对导弹典型机电产品电机进行贮存失效分析,同时考虑双参数退化失效和突发失效对电机贮存可靠性的影响。首先,以具有随机效应的非线性Wiener过程描述电机贮存退化失效过程中的非线性、随机性和样本差异性。然后,采用Weibull分布描述突发失效过程规律,并考虑退化程度对突发失效的影响。最后,利用Copula函数刻画退化性能参数之间的相互作用关系,建立双参数退化-突发竞争失效模型,并给出基于两步极大似然估计的参数估计方法。结果 以仿真导弹电机退化突发失效数据为例进行分析,实现了基于双参数退化-突发竞争失效模型的系统可靠性评估,得到电机贮存5 a时的可靠度估计值为0.465。结论 所构建的双参数随机退化与突发失效相关的竞争失效模型有效,为导弹机电产品可靠性验证评估及寿命预测提供了相应的理论依据。     

加氢装置高压串低压风险分析及对策

针对加氢装置高压串低压的特点,分析讨论了其存在的火灾、爆炸、人身伤害、中毒等风险,针对这些风险提出对应的安全防范措施。     

一株多菌灵降解菌包埋条件及降解特性

采用海藻酸钠(SA)和聚乙烯醇(PVA)对1株多菌灵降解菌进行包埋,并对最佳包埋条件及包埋后的降解效果进行研究.结果表明:SA包埋法的最佳条件为:菌液与2% SA按1:5体积比混合,在4% CaCl2溶液中室温交联24h.PVA包埋法的最佳条件为:菌液与10%PVA按1:5比例混合,在3%CaCl2溶液中室温交联24h.活化48h后,在30℃、 pH6的条件下,SA包埋的多菌灵降解菌对多菌灵的降解率可达80.4%.PVA包埋的降解菌的降解率为76.3%.     

大气氢氟碳化物采样分析和质量控制方法研究

用自组装采样系统冲洗双口不锈钢采样罐,并采集大气样品至1.36×105 Pa,在实验室利用自组装气相色谱-质谱联用(GC-MS)系统分析样品,对6种主要氢氟碳化物(HFCs)分析精度为0.24%~1.02%.空白实验表明,采样-分析过程未引入污染.通过压力-体积曲线对进样压力变化的影响进行了校正.回收率实验及存储实验表明,6种HFCs回收率范围为99.5%~100.4%,存储112d内HFCs浓度没有显著变化.在北京上甸子区域大气本底站采集80m梯度塔顶大气样品并分析,2个串联采样罐HFCs浓度差值范围为0.04×10-12~0.16×10-12.采样分析与同期该站GC-MS在线观测系统获得的HFCs浓度差值范围为-0.17×10-12~-0.86×10-12.本研究建立的采样-分析-质量控制方法和流程适用于大气中HFCs高精度观测.     

太湖湖内综合治理技术探讨

简要介绍和探讨了在太湖已有一定研究基础并可供开展的局部重污染湖区底泥疏浚、湖区北部藻类收集、生态渔业建设、取水口水源净化保护工程和水生植被保护和重建等5种湖内综合治理技术、比较了它们的适用范围和预期效果。     

太湖富营养化现状,趋势及其综合整治对策

在１９９４￣１９９５年太湖９次富营养化现状调查基础上，评价了太湖各期营养程度，并分析了３５年来主要营养物含量发展趋势。结果表明，太湖营养水平处于中富向富营养过渡状态，中富面积约占全湖面积的７０％以上，夏季富营养及重富营养水域出现在北部湖区的梅梁湖、五里湖和西部沿岸带，约占全湖面积的１０％，３０多年来湖体中形态营养元素含量有较大增长，尤其是磷增长最快，使氮磷比下降。太湖水源地梅梁湖营养程度由１９８１     

不同垃圾焚烧设备中二英的排放特征和I-TEQ指示物的研究

分析了国内3种不同类型的垃圾焚烧设备中二英化合物的排放特征,不同PCDD/F单体与I-TEQ的相关性以及23478-PeCDF与I-TEQ的线性回归分析.得到了不同类型的垃圾焚烧设备中二英同系物的统计学分布特征.结果发现,生活垃圾、医疗垃圾和危废焚烧炉中二英（PCDD/F）同系物分布虽有一定差异,但变化不大,与生活垃圾焚烧炉和危废焚烧炉相比,医疗垃圾焚烧炉中二英同系物的分布稍有区别.在3种焚烧炉的烟道气中体积分数最大的是OCDD和1234678-HpCDF,分别为12.3％～23.0％和15.0％～19.7％;而对I-TEQ贡献最大的则是23478-PeCDF,体积分数为33.1％～34.5％,远远高于其它的PCDD/F单体.通过对不同的PCDD/F单体与I-TEQ的相关性分析发现：23478-PeCDF与I-TEQ的相关性最好,相关系数R²为0.93～0.98;而毒性最大的2378-TCDD与I-TEQ的相关性较差,R²为0.29～0.49;体积分数最大的OCDD与I-TEQ的相关性很差,R²为0.03～0.12;体积分数较大的1234678-HpCDF与I-TEQ也有较好的相关性,R²为0.62～0.87,但依然次于23478-PeCDF.通过23478-PeCDF与I-TEQ线性回归的结果发现：即使I-TEQ的浓度范围为5～6个数量级,23478-PeCDF与I-TEQ也表现出很好的线性关系,对于不同的垃圾焚烧设备,回归曲线斜率为在1.16～1.40之间,相关系数R²在0.94～0.97之间.     

黑龙江省秸秆露天焚烧污染物排放清单及时空分布

以黑龙江省为例,采用排放因子法计算了2016年秸秆露天焚烧污染物排放清单,分析了污染物的时空分布特征.结果表明,黑龙江省秸秆露天焚烧各污染物排放量为：CO₂ 1314.09万t、CO 41.92万t、CH₄ 3.77万t、NMVOCs 8.35万t、NH₃ 0.65万t、BC 0.44万t、OC 3.13万t、SO₂ 0.50万t、NO_X 3.28万t、PM₁₀ 8.81万t、PM_2.5 10.14万t.在95%的置信区间确定了排放清单的不确定性,不确定性范围为NO_X的±86%的低值到CO的±187%的高值.通过可靠性分析推断,本文的排放清单是合理的.玉米和水稻秸秆露天焚烧对同种大气污染物的贡献高于其他作物秸秆.大气污染物排放高值区位于黑龙江省西部和东部,污染物排放的时段在全年范围内具有明显的双峰特征.秸秆露天焚烧率的下降能有效促进大气污染物的减排,且农垦地区集约化和规模化的管理模式能有效控制秸秆露天焚烧.