环境监测中POPs分析的关键问题与对策

系统介绍了采用EPA8081A与8082方法进行环境样品中持久性有机污染物(POPs)分析的关键问题与对策。包括POPs的气相色谱分析与验证双柱系统,DDT与异狄氏剂在进样系统中的分解及其处理方法,应用目测识别法、手型法与透明复印胶片法等经验方法快速定性多氯联苯(PCBs)、氯丹与毒杀芬等多峰化合物,影响外标法准确定量PCBs、氯丹与毒杀芬等多峰POPs的关键因素,以及质量控制要求。提出应根据中国POPs的环境污染特点,建立相应的POPs标样库与标准图谱库,为中国的POPs污染调查与环境监测提供技术支持。     

搅拌子吸附-热脱附-气相色谱-质谱法分析北京大气中33种多氯联苯

用包覆聚二甲基硅氧烷(PDMS)吸附层的搅拌子作被动大气采样器,建立了搅拌子吸附-热脱附-气相色谱-质谱法(SBSE-TD-GC-MS)分析大气中多氯联苯(PCBs)的方法。优化后的热脱附温度为280℃,热脱附时间为6 min,聚焦冷阱的温度为-40℃,33种PCB单体的热脱附残留比例低于7%。验证了方法的线性、精密度和重复性。标准曲线5个点线性关系良好,33种PCB单体的相关系数r>0.998。方法精密度验证的相对标准偏差(RSD)为0.79%~20.2%(n=8),日内重复性实验的RSD为0.43%~29.8%(n=10),日间重复性实验的RSD为3.20%~29.6%(n=20),方法检出限(LOD)为0.01~2.51 pg,回收率为98%±18%。将建立的方法用于北京大气中PCBs的分析。检出8种PCB单体,质量为2.94~129 pg。在32 d的采样周期内PCB-52、PCB-123、PCB-155一直处于线性吸附阶段,而PCB-1和PCB-3经过了线性吸附阶段、曲线吸附阶段和平衡阶段。研究结果表明,SBSE-TD-GC-MS可以用于大气中PCBs的样品采集和快速分析。     

SEMIPERMEABLE MEMBRANE DEVICES USED TO ESTIMATE BIOCONCENTRATION OF POLYCHLORINATED BIPHENYLS1

ABSTRACT: Aquatic organisms passively accumulate hydrophobic organic compounds, such as polychlorinated biphenyls, even when ambient water concentrations of the contaminant are below analytical detection limits. However, contaminant concentrations in tissue samples are subject to an inherently high level of variability due to differences in species, life stage, and gender bioconcentration potentials. Semipermeable membrane devices (SPMDs) were used to sample Aroclor 1254, a mixture of readily bioconcentrated polychlorinated biphenyls (PCBs), in a contaminated wetland near Flat Top, WV. The devices consisted of triolein, a lipid found in fish, enclosed in a polyethylene membrane. SPMDs were deployed in the water column and in direct contact with wetland sediments along a previously identified concentration gradient of PCBs. The devices were retrieved after a 25-day exposure period. Analytes were recovered by dialyzing the devices in nanograde hexane. Hexane dialysates were condensed and analyzed by gas chromatography. All deployed devices sequestered quantifiable amounts of Aroclor 1254. Water-column SPMDs accumulated PCBs far in excess of ambient water concentrations. The devices contacting sediments accumulated PCBs at all sites, though accumulated concentrations did not exceed concentrations in sediment. Patterns of PCB concentration in the devices corresponded to the identified gradient at the site. Results from the water-column SPMDs were used to estimate the concentration of the dissolved, bioavailable fraction of PCBs present in the water column. These concentrations ranged from 0.01 to 0.09 μg/L of bioavailable Aroclor 1254.     

长江口滨岸潮滩动物体中PCBs和OCPs的分布

利用GC-ECD对长江口滨岸潮滩中动物进行研究,分析了PCBs和OCPs(DDTs和HCHs)的含量分布.结果表明PCBs含量水平为43.7～1260.4ng/g,均值为342.5ng/g;DDTs为1.5～159.4ng/g,均值为33.7ng/g;HCHs为0.9～77.0ng/g,均值为13.0ng/g.从空间上看,同种动物对不同污染物的累积和同种污染物在不同动物体内的累积均无明显的规律,但同属种样品则有雄性个体污染物含量高于雌性个体、小个体高于大个体的规律.对动物体内POPs污染进行了初步评价,结果显示:该区动物均不同程度地受到污染,污染已达中等水平.     

鼋头渚不同年龄夜鹭卵中多氯联苯污染状况及分布特征

通过对太湖鼋头渚2000年采集的2龄、3龄和4龄夜鹭所产卵中15种多氯联苯同系物残留状况的研究,发现所有样品中均检出多氯联苯,残留量最高的为PCB₁₁₈,PCB₈₇,PCB₁₀₁和PCB₁₅₃,占PCBs残留量的75%～85%.含5～6个氯原子的同系物在夜鹭卵中的PCBs残留量明显高于其它类型的同系物.同时,多氯联苯残留量随亲鸟年龄增加而明显增加.4龄卵样分别比3龄、2龄卵样中PCBs残留量高出47.5%和60.9%.统计处理结果表明:多氯联苯残留总量与亲鸟年龄呈正相关(p=0.05).PCBs总量与亲鸟年龄呈正相关(p=0.05).与欧美日等国家同类研究结果中PCB₁₅₃残留量最高的情况略有不同,本研究在夜鹭卵中发现残留量最高的是PCB₁₁₈,占PCBs残留总量的30%左右,PCB₁₅₃含量仅为PCBs残留总量的17%左右.     

西葫芦对土壤持久性有机氯化物污染的指示性研究

西葫芦(Cucurbita pepo L.)对土壤中持久性有机氯化物的超强吸收能力已被证实,意味其具有指示区域土壤持久性有机氯化物污染状况的潜能。本研究采用农田小区试验,考察了西葫芦不同组织器官(根、过渡茎、茎、叶和果实)在6个生长期对有机氯化物的累积吸收行为;采用同位素稀释高分辨气相色谱-高分辨质谱法,分析了种植土壤及西葫芦各组织器官中的21种有机氯农药(OCPs)和18种多氯联苯(PCBs)。结果表明,西葫芦可将根吸收的OCPs和PCBs传递到过渡茎和茎。不同生长期采集的西葫芦根、过渡茎和茎中的OCPs和PCBs浓度基本稳定,无明显生物稀释效应,且此3个组织器官中OCPs和PCBs的分布模式与土壤中的分布模式基本一致。因此,可以用西葫芦根和茎中持久性有机氯化物的浓度指示土壤中持久性有机氯化物的污染水平,根和茎的采样时间可以不受西葫芦生长期的限制。     

湖鲟(Acipenser fulvescens)早期生命阶段对2,3,7,8-四氯二苯并-p-二恶英和3,3'4,4'5-五氯联苯的敏感性研究

自20世纪中叶以来,五大湖区的水生食物网就已受到多氯联苯化合物(PCBs)的污染。对于长寿命鱼类,如湖鲟(Acipenser fulvescens),由于缺乏该物种的相对敏感性信息,一直无法确定其PCB暴露的风险。本文的研究目标就是评估湖鲟早期生命阶段对3,3''4,4''5-五氯联苯(PCB-126)或2,3,7,8-四氯二苯并-p-二恶英(TCDD)暴露的敏感性。死亡率、生长、形态和组织病理学、游泳能力和活动水平都被用作评估终点。心包和卵黄囊水肿、管状心脏、卵黄囊出血和体长较小是TCDD和PCB-126暴露中最常见的病理症状,早在受精4 d后就开始出现,其中许多的病理都以一种剂量依赖的方式发生。湖鲟体内PCB-126和TCDD的半致死剂量分别为5.4 ng/g egg(95%置信区间,3.9-7.4 ng/g egg)和0.61 ng/g egg (0.47-0.82 ng/g egg)。由此产生的PCB-126的相对强度因子(0.11)远大于世界卫生组织对鱼的估计值(毒性当量因子=0.005),这表明目前的风险评估可能低估了PCB对湖鲟的毒性。在受精60 d后,从半致死剂量中幸存的湖鲟的游泳活性和耐力均有所下降。阈值和半数效应毒性值表明,与在北美发现的另一种鲟鱼属Scaphirhynchu相比,湖鲟对PCB和TCDD更为敏感。事实上,在大湖区和其他地方的湖鲟种群都容易受到PCB/ TCDD诱导,使胚胎发育受到影响,游泳能力下降。
精选自Tillitt, D. E., Buckler, J. A., Nicks, D. K., Candrl, J. S., Claunch, R. A., Gale, R. W., Puglis, H. J., Little, E. E., Linbo, T. L. and Baker, M. (2017), Sensitivity of lake sturgeon (Acipenser fulvescens) early life stages to 2,3,7,8-tetrachlorodibenzo-P-dioxin and 3,3′,4,4′,5-pentachlorobiphenyl. Environmental Toxicology and Chemistry, 36: 988–998. doi: 10.1002/etc.3614
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3614/full
     

中国部分沿海海域水体中溶解态有机氯农药和多氯联苯的残留分布特征

分析调查了中国部分海域海水中溶解态有机氯农药(OCPs,25种)和多氯联苯(PCBs,6种)的残留分布特征。结果表明,所有采样点都不同程度地受到了OCPs和PCBs的污染,其中福建省福州平潭和莆田湄洲岛的OCPs污染较为严重,浓度分别达到1752.59和796.19 ng/L;而辽宁省的大连老虎滩OCPs污染较轻,浓度为53.63 ng/L。各采样点海域海水中HCHs污染程度一般高于DDTs,HCHs主要以早期残留为主;根据DDT/DDTs的比值推测,在福州平潭、莆田湄洲岛和珠海淇澳岛水体显示有新的DDT输入。在各海域水体中溶解态PCBs的浓度为33.55~474.92 ng/L,均超过了美国环保局规定的海水浓度限值。因此目前我国沿海海域水体中持久性有机污染物有机氯农药和多氯联苯污染仍不能忽视。     

岩溶地下水水体中有机氯农药和多氯联苯的残留特征及健康风险评价

采用气相色谱-微池电子捕获检测器（GC-μECD）测定南山老龙洞岩溶地下水水体中有机氯农药（OCPs）和多氯联苯（PCBs）残留量,并探究了OCPs和PCBs的浓度、分布和来源等残留特征.结果表明,OCPs总浓度范围为34.8~623.2 ng·L^-1,均值为215.6 ng·L^-1,其中,HCHs、DDTs和其它类OCPs总浓度范围分别为8.2~23.6、4.5~363.7和22.2~235.9 ng·L^-1,均值分别为15.9、104.5和95.3 ng·L^-1;PCBs总浓度范围为6.0~40.7 ng·L^-1,均值为16.8 ng·L^-1.总体而言,OCPs和PCBs污染处于中上水平;多重比较结果显示部分OCPs和PCBs平均浓度具有统计学意义上的显著差异.研究区各采样点水体中污染水平差异较大,但OCPs和PCBs的季节分布相对均匀.源解析表明,HCHs源于周围环境中林丹的输入;DDTs源于近期工业DDT的非法使用;其它类OCPs源于大气沉降和农业活动输入;PCBs来源既有历史残留,又有企业排污活动;Pearson相关分析表明部分有机卤素污染物具有同源性,或有类似的来源和分解机制.结合健康风险评价模型,研究区饮用水不会对人体健康产生明显危害,但儿童对污染物的敏感性高于成人.     

Distribution of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in surface water and sediments from Baiyangdian Lake in North China

Persistent organochlorine compounds, including hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs) and polychlorinated biphenyls (PCBs) were analyzed in surface water and sediments from Baiyangdian Lake, North China. Total concentrations of HCHs, DDTs and PCBs in surface water were in the range of 3.13-10.60, 4.05-20.59 and 19.46-131.62 ng/L, respectively, and total concentrations of HCHs, DDTs and PCBs in sediments were 1.75-5.70, 0.91-6.48 and 5.96-29.61 ng/g dry weight, respectively. Among the groups of HCHs (sum of α-HCH, β-HCH, γ-HCH and δ-HCH) and DDTs (sum of DDT, DDD and DDE), the predominance of β-HCH, DDE and DDD in water and sediment samples was clearly observed. This observation suggested that β-HCH was resistant to biodegradation and the DDTs had been transformed to its metabolites, DDE and DDD. For PCBs, penta-, hexa- and hepta-chlorinated congeners were the most abundant compounds in the both phases. Furthermore, the partitioning of chlorinated compounds between sediment and water was investigated to understand their transport and fates in aquatic ecosystems. The results indicated that average logs of organic carbon-normalized sediment-water partition coefficients (logK_oc') for OCPs varied between 3.20 and 5.53, and for PCBs, logK_oc' values ranged from 3.19 to 5.57. The observed logK_oc' was lower than their equilibrium logK_oc predicted from linear model, which may be attributed to the solubility enhancement effect of colloidal matter in water phase and the disequilibrium between sediment and water.