长江典型江段水体PAHs的分布特征、来源及其生态风险

针对我国长江典型江段丰、平、枯不同时期的地表水,采用了固相萃取—气相色谱质谱联用(GC-MS)的分析技术,调查了16种优先控制多环芳烃(PAHs)的污染状况。研究了长江干流PAHs的污染水平和分布特征,并在定量分析的基础上评估了长江干流PAHs的来源和生态风险。结果显示,Σ₁₆PAHs浓度范围为2.22～1450.91ng/L,均值为107.04ng/L,其中,平水期武汉江段Σ₁₆PAHs浓度最高,均值为1050.64ng/L,长江干流PAHs污染状况与近5a国内其他水体相比处于中等偏低水平。空间分布上长江典型江段地表水中Σ₁₆PAHs从上游攀枝花江段到下游南京江段呈现出先上升后下降的趋势;时间分布上Σ₁₆PAHs的变化趋势为平水期(187.78ng/L)>丰水期(73.30ng/L)>枯水期(38.02ng/L)。由同分异构比值法分析表明:在枯水期和平水期中,煤炭、生物质燃烧和石油源是长江干流PAHs的主要来源,而丰水期PAHs主要源于煤炭、生物质燃烧,其中南京江段PAHs的来源较为复杂。采用物种敏感性分布评估法对PAHs进行生态风险评估,结果显示长江典型江段地表水中PAHs尚未对水生生物造成显著的负面影响,与历史数据比对表明现阶段长江干流PAHs生态风险低于长江大保护政策实施前的生态风险。     

在线表征萘二次有机气溶胶硝基多环芳烃

硝基多环芳烃(NPAHs)广泛存在于大气气溶胶中,是棕色碳的重要组成部分.萘和其他多环芳烃是NPAHs的重要前体物.为研究NO₂对NPAHs形成的影响,本文利用气溶胶激光飞行时间质谱仪(ALTOFMS)在线测定不同NO₂浓度下萘光氧化形成的二次有机气溶胶(SOA)的NPAHs组分.实验结果表明,NO₂对NPAHs的产生和萘SOA的形成有促进作用.通过ALTOFMS在线检测、模糊C均值(FCM)聚类分析,结合离线电喷雾电离质谱验证,测得萘酚和羰基化合物是不存在NO₂时萘SOA粒子主要成分,而通过OH-萘加合物和萘酚硝化产生的硝基萘、二硝基萘、硝基萘酚和二硝基萘酚及其衍生物是NO₂存在时萘SOA粒子的主要组分.这为城市大气高浓度NO_x背景下,研究NPAHs的化学组分和形成机理提供了实验依据.     

某大型化工企业周边居民区积尘中多环芳烃调查及健康风险评价

以江苏省某大型化工企业周边居民区为研究区域,调查企业主导风的下风向2 km范围内的居民区以及对照区积尘中多环芳烃(PAHs)含量,对16种PAHs污染分布和特征进行研究,并评估积尘PAHs通过暴露途径对人群健康风险。结果表明:居民区积尘中16种PAHs全部检出,污染区∑PAHs均值为2 294μg/kg,明显高于对照区145μg/kg;污染区7个测点中有6个测点苯并(a)芘出现超标,超标倍数为0. 17～2. 5倍;所测的16种PAHs化合物中蒽、荧蒽、芘、、苯并(b)荧蒽、苯并(k)荧蒽、苯并(a)芘浓度相对较高;通过PAHs主成分分析和特征比值判断,不完全燃烧源对积尘中PAHs贡献率达77. 4%,污染区PAHs来源呈现石油燃烧、煤燃烧以及石油源的复合污染特征,对照区PAHs主要来源为煤的不完全燃烧;以苯并(a)芘毒性等效浓度进行风险评估,污染区致癌风险值明显高于对照区,儿童摄入PAHs风险总体高于成人;对照区儿童和成人致癌风险均小于1×10~(-6),不存在致癌风险;污染区儿童和成人平均致癌风险值分别为3. 95×10~(-6)、2. 65×10~(-6),在可接受范围内,但存在潜在致癌风险。     

优化QuEChERS结合HPLC测定沉积物中14种多环芳烃

以美国国家标准技术研究院(NIST)2种沉积物标样SRM 1944和SRM 1941b为研究对象,建立并优化了QuEChERS结合HPLC测定沉积物中14种多环芳烃的前处理方法,并与传统索氏提取进行比较。优化后的QuEChERS方法:样品经乙腈浸泡后,超声15 min,漩涡振荡3 min,以NaCl和无水MgSO_4盐析,提取液经PSA净化后经HPLC-FLD测定。该条件下14种PAHs的方法检出限为0.5~5.0μg/kg,SRM 1944和SRM 1941b中PAHs回收率分别为73.4%~104.9%和71.9%~96.4%,相对标准偏差分别为0.47%~3.45%和0.87%~3.05%。索氏提取SRM 1944与1941b回收率分别为78.9%~109.3%和80.9%~108.2%,相对标准偏差分别为1.46%~10.3%和1.27%~10.8%。优化后的QuEChERS回收率与索氏提取较为接近,但具有更高的精密度。将该方法用于实际海洋沉积物提取,PAHs测定值与索氏提取较为接近。优化后的QuEChERS方法满足批量沉积物样品中PAHs的快速测定要求。     

加速溶剂萃取-高效液相色谱法测定固体废物中多环芳烃

建立了固体废物中多环芳烃的快速溶剂萃取(ASE)-高效液相色谱(HPLC)检测方法。加速溶剂萃取仪在温度100℃、压强1.05 MPa条件下,以体积比1:1的丙酮和二氯甲烷为萃取剂,萃取5 min,萃取液采用固相萃取柱或凝胶色谱净化。灰渣和污泥中的PAHs的方法检出限分别为1.03~1.96 μg/kg和4.71~7.04 μg/kg,相对标准偏差分别为4.0%~13.8%和3.3%~13%,加标回收率分别为73.2%~89.8%和67.7%~90.5%。     

Source apportionment of polycyclic aromatic hydrocarbons in Lake Baikal water and adjacent air layer

The composition of polycyclic aromatic hydrocarbons (PAHs) in Lake Baikal water and adjacent air layer and PAH emission composition profiles of possible sources were investigated. Analysis of emission composition data showed that the source profiles could not be grouped by fuel type or pyrogenic/petrogenic origin. Because of the similarity of source PAH profiles, the drawing of 3D mixing diagrams was the only way to check whether some of the potential PAH sources were the true sources. The mixing diagrams showed that the sources of air pollution were paper mills and wood burning and that the sources of water pollution were coal-fired and oil-fired boilers. The common source for both air and water was only oil and petroleum products. To determine the locations of PAH sources, their contributions to air and water pollution were calculated and mapped. Based on the results, air and water were polluted from both local and regional sources. The location of the zone influenced by a particular source was conditioned by physical properties of source emission, direction of air/water flows that transfer PAHs and temperature differences between mixing air/water flows.     

The effect of clay catalyst on the chemical composition of bio-oil obtained by co-pyrolysis of cellulose and polyethylene

Cellulose/polyethylene (CPE) mixture 3:1, w/w with and without three clay catalysts (K10 – montmorillonite K10, KSF – montmorillonite KSF, B – Bentonite) addition were subjected to pyrolysis at temperatures 400, 450 and 500 °C with heating rate of 100 °C/s to produce bio-oil with high yield. The pyrolytic oil yield was in the range of 41.3–79.5 wt% depending on the temperature, the type and the amount of catalyst. The non-catalytic fast pyrolysis at 500 °C gives the highest yield of bio-oil (79.5 wt%). The higher temperature of catalytic pyrolysis of cellulose/polyethylene mixture the higher yield of bio-oil is. Contrarily, increasing amount of montmorillonite results in significant, almost linear decrease in bio-oil yield followed by a significant increase of gas yield. The addition of clay catalysts to CPE mixture has a various influence on the distribution of bio-oil components. The addition of montmorillonite K10 to cellulose/polyethylene mixture promotes the deepest conversion of polyethylene and cellulose. Additionally, more saturated than unsaturated hydrocarbons are present in resultant bio-oils. The proportion of liquid hydrocarbons is the highest when a montmorillonite K10 is acting as a catalyst.     

沉积物中2株多环芳烃降解菌的分离鉴定及其对菲、荧蒽的降解特性

从长江重庆主城段近岸表层沉积物中,分离出2株能以菲和荧蒽为碳源和能源生长的菌株(命名为CJ1、CJ2),经鉴定分别为黄杆菌属(Flavobacterium sp.)和克雷伯氏杆菌属(Klebsiella sp.)。进行了菲和荧蒽在初始浓度为20~200 mg/L条件下的生长代谢过程与降解动力学分析。结果表明,CJ1对菲和荧蒽的降解效能总体优于CJ2。15 d时CJ1和CJ2对菲的降解率最高分别为74.3%和70.3%;30 d时CJ1和CJ2对荧蒽的降解率最高分别为58.2%和49.9%。初始浓度为200 mg/L时,两菌株对菲、荧蒽的降解受到一定程度抑制。     

萘降解菌的筛选及其对多环芳烃的降解

从柴油污染土壤中筛选分离出一株萘降解菌N-3,进行了菌种鉴定及萘双加氧酶基因(nah)验证,并考察了该菌对不同种类多环芳烃(PAHs)的降解能力及降解过程中脱氢酶活性的变化。实验结果表明:该菌为铜绿假单胞菌(Pseudomonas aeruginosa),含有nah基因;当分别对液体培养基中质量浓度为50 mg/L的萘、菲、蒽、芘、芴降解84 h时,菌株N-3对萘、菲、蒽、芘、芴的降解率分别为28.81%,34.83%,36.65%,27.50%,23.47%。菌株N-3的脱氢酶活性与其对不同PAHs的降解率呈一定的正相关性。该菌不仅能有效降解萘,且对其他种类PAHs也有一定降解作用。     

菌源对多环芳烃降解菌的筛选及降解性能的影响

高效降解菌的筛选对利用生物修复技术有效去除环境中的多环芳烃具有重要意义。分别以石油污染土壤和焦化废水活性污泥为菌源,分离出芘降解菌和混合PAHs(菲、荧蒽和芘)降解菌共14株并对其降解性能进行对比研究。结果表明,筛选得到的菌株分别属于9个菌属,其中2种菌源共有的菌属为Mycobacterium sp.、Ralstonia sp.和Shinella sp.。芘和PAHs的高效降解菌(CP16和CM32)均属于分支杆菌属(Mycobacterium),来源于焦化废水活性污泥;菌株CP16对芘(50mg/L)的7 d降解率为74.99%,CM32对PAHs(菲50 mg/L、荧蒽和芘各10 mg/L)的7 d降解率为100%。因此,以焦化废水活性污泥为菌源更有利于获得高效的多环芳烃降解菌。