环境科学  2023, Vol. 44 Issue (7): 3809-3819   PDF    
引用本文
徐振鹏, 钱雅慧, 洪秀萍, 罗钟庚, 高秀龙, 梁汉东. 淮北孙疃矿区地表尘中多环芳烃类化合物的污染特征及致癌风险评价[J]. 环境科学, 2023, 44(7): 3809-3819.
XU Zhen-peng, QIAN Ya-hui, HONG Xiu-ping, LUO Zhong-geng, GAO Xiu-long, LIANG Han-dong. Contamination Characteristics and Risk Assessment of Polycyclic Aromatic Compounds in Surface Dust of Suntuan Mining Area in Huaibei[J]. Environmental Science, 2023, 44(7): 3809-3819.
淮北孙疃矿区地表尘中多环芳烃类化合物的污染特征及致癌风险评价
徐振鹏1,2, 钱雅慧1,2, 洪秀萍3, 罗钟庚1,2, 高秀龙1,2, 梁汉东1,2     
1. 煤炭资源与安全开采国家重点实验室, 北京 100083;
2. 中国矿业大学(北京)地球科学与测绘工程学院, 北京 100083;
3. 淮北师范大学生命科学学院, 淮北 235000
收稿日期: 2022-09-06; 修订日期: 2022-09-30
基金项目: 国家自然科学基金项目(41772157, 41902172); 煤炭资源与安全开采国家重点实验室开放基金项目(SKLCRSM21KFA11); 安徽省自然科学基金项目(2008085QD169)
作者简介: 徐振鹏(1996~), 男, 硕士研究生, 主要研究方向为环境监测与评价, E-mail: 402148455@qq.com
通信作者: 梁汉东, E-mail: hdl6688@cumtb.edu.cn
摘要: 淮北孙疃矿区是华北两淮地区典型的煤炭资源开采基地.以往涉及煤矿区地表尘的环境研究多集中在重金属和水溶性离子等, 对多环芳烃类化合物(PACs)研究较少.利用气相色谱-三重串联四极杆质谱(GC-MS/MS)检测了孙疃矿区及周边环境地表尘中16种母体多环芳烃(16PAHs)、烷基多环芳烃(aPAHs)及部分含氧多环芳烃(OPAHs)的含量.结果表明, 孙疃矿区地表尘中ΣPACs含量范围为283.8~36 852.5 μg ·kg-1 (均值为4 114.2 μg ·kg-1).其中, ΣaPAHs(均值2 593.8 μg ·kg-1)约为Σ16PAHs(均值1 074.9 μg ·kg-1)的2.4倍, 是PACs污染的主要贡献者.地表尘中16PAHs和aPAHs在组成上均以相对分子质量低的PACs为主.OPAHs含量较低, 均值为445.6 μg ·kg-1.同时, PACs污染主要集中在矿区周边及煤矸石填埋道路附近.利用正定矩阵因子分解(PMF)推测研究区主要受成岩源影响, 其次是煤和生物质燃烧, 交通源及石油产品泄漏的占比较小.特征比值结果显示, 当Σ16PAHs/ΣPACs < 0.25时主要受煤矿区污染.PMF结合终生致癌风险(ILCR)结果显示, 研究区对儿童存在潜在致癌风险, 风险主要来自煤和生物质燃烧及煤炭开采.我国淮河流域煤矿区众多, 研究结果可为煤炭开采区PACs的污染防治提供参考.
关键词: 煤矿区      多环芳烃类化合物(PACs)      地表尘      源解析      致癌风险     
Contamination Characteristics and Risk Assessment of Polycyclic Aromatic Compounds in Surface Dust of Suntuan Mining Area in Huaibei
XU Zhen-peng1,2 , QIAN Ya-hui1,2 , HONG Xiu-ping3 , LUO Zhong-geng1,2 , GAO Xiu-long1,2 , LIANG Han-dong1,2     
1. State Key Laboratory of Coal Resources and Safe Mining, Beijing 100083, China;
2. College of Geoscience and Surveying Engineering, China University of Mining and Technology, Beijing 100083, China;
3. College of Life Sciences, Huaibei Normal University, Huaibei 235000, China
Abstract: The Suntuan mining area of Huaibei is a typical coal resource mining base in the Huainan-Huaibei areas in North China. Previous environmental studies related to surface dust in coal mining areas mainly focused on heavy metals and water-soluble ions, with little research on polycyclic aromatic compounds (PACs). In this study, gas chromatography-triple tandem quadrupole mass spectrometry (GC-MS/MS) was used to determine the contents of 16 parent polycyclic aromatic hydrocarbons (16PAHs), alkyl polycyclic aromatic hydrocarbons (aPAHs), and some oxygenated polycyclic aromatic hydrocarbons (OPAHs) in surface dust from the Suntuan mining area and surrounding environment. The results showed that the ΣPACs concentration range of surface dust in the Suntuan mining area was 283.8-36 852.5 μg ·kg-1 (mean: 4 114.2 μg ·kg-1). ΣaPAHs (mean: 2 593.8 μg ·kg-1) was 2.4 times higher than Σ16PAHs (mean: 1 074.9 μg ·kg-1), which was the main contributor to PAC pollution. The composition of 16PAHs and aPAHs in surface dust was dominated by low molecular polycyclic aromatic hydrocarbons. The average OPAH content was 445.6 μg ·kg-1. At the same time, PAC pollution was mainly concentrated around the mining area and near the road of a coal gangue landfill. Based on the positive matrix factor (PMF) analysis, it was inferred that the study area was mainly affected by petroleum sources, followed by coal and biomass combustion, and traffic sources and petroleum product leakage accounted for a relatively small proportion. Based on the ratio and distribution pattern of 16PAHs and aPAHs, it was inferred that when Σ16PAHs/ΣPACs < 0.25, it was mainly polluted by the coal mining area. The results of PMF combined with lifetime carcinogenic risk (ILCR) showed that there were potential carcinogenic risks for children near the study area, mainly from coal and biomass burning and coal mining. There are many coal mining areas in Huaihe River Basin in China. The results of this study can provide reference for pollution prevention and control of PACs in these coal mining areas.
Key words: coal mine area      polycyclic aromatic compounds (PACs)      dust      source analysis      carcinogenic risk     

多环芳烃类化合物(polycyclic aromatic compounds, PACs)是自然界中分布广泛的、涉及有机质不完全燃烧和热解过程中难以避免产生的持久性有机污染物[1, 2].由于PACs具有“三致效应”[3, 4], 国内外颁布了关于16种母体多环芳烃(16PAHs)的各项标准, 并将其列为环境优先控制污染物[5~7].近年来, 随着对16PAHs及其衍生物的深入研究, 烷基多环芳烃(aPAHs)和含氧多环芳烃(OPAHs)因其与16PAHs毒性接近甚至更强而引起关注[8, 9], 且有研究表明, aPAHs较16PAHs在生物体内的富集时间更长[10].OPAHs作为多环芳烃的极性衍生物, 被认为是多环芳烃化学降解的终产物[11], 因水溶性较高而在土壤中流动性更好, 并能随着多环芳烃的降解而富集[12].因此, 多环芳烃衍生物在无形中威胁着生态环境及人体健康.目前, 对aPAHs与OPAHs的研究多集中在土壤[13]、河流[14]、沉积物[15, 16]和气溶胶[17, 18]中, 且研究区多为城市[19]、农业区[20]和工业区[21]等, 但是针对煤矿区多环芳烃衍生物的研究较少.

地表尘是PACs的重要载体[22].作为一种复杂的颗粒混合物, 地表尘可能来源于建筑废料、车辆尾气、轮胎磨损颗粒和植物碎屑等[23].以往地表尘中PACs的研究多集中在城市扬尘[24]、室内灰尘[25]和路边尘[26]等, 且目标污染物多为16PAHs, 关于地表尘中多环芳烃衍生物的研究较少.地表尘中的PACs可以在外界环境影响下通过挥发和再悬浮进入大气[27], 也可因降雨以径流形式输送到水环境中[28], 还能沉积在植物叶片表面[29].同时, 手口摄入、呼吸吸入和皮肤接触再悬浮的地表尘颗粒对人体健康存在严重威胁[30].尽管国内外已逐步开展对地表尘中PACs污染的研究工作, 但很少深入研究受煤矿开采及煤矸石颗粒影响地区地表尘中PACs的污染情况, 相较于传统城市道路灰尘, 煤矿周边地表尘的成分更复杂, 存在的环境风险值得进一步研究.本文通过对淮北孙疃矿区及周边地表尘中PACs的研究, 了解受煤矿区开采及煤矸石堆积影响的地区中PACs的含量、组成、空间分布、来源和健康风险, 以期为煤矿区PACs的污染控制及其环境治理提供参考.

1 材料与方法 1.1 研究区概况

安徽省煤炭消耗量较大, 土壤中16PAHs含量在全国范围内处于较高水平[31, 32], 其中, 两淮地区煤种齐全、煤质优良、分布广泛且储量丰富, 已成为华北重要的煤炭资源基地[33].孙疃矿区隶属于安徽省濉溪县淮北煤田中部(33°33′~33°35′30″N, 116°42′30″~116°46′E), 含煤地层主要为石炭系和二叠系[34].与淮北煤田其他矿区相比, 孙疃矿区周边水系丰富, 紧邻矿区的浍河作为淮河北岸的支流, 极易受到矿区开采影响.同时, 孙疃矿区周边无工业区, 不易引入其他类型的污染源.因此, 孙疃矿区既具有淮北煤田典型矿区的共性, 又有其地理位置上的特殊性.本研究以淮北孙疃矿区为中心, 周围2 km范围内按照圆形布点采样法共布置64个采样点.采样时用毛刷收集地表尘样品, 将5 m2范围内采集的3个平行样混合均匀, 去除落叶石块等杂质后用铝箔纸包裹置于塑封袋中(编号A1~A64), 每个样品不少于500 g, 并用手持式GPS记录经纬度坐标(图 1).

图 1 淮北孙疃矿区地表尘采样点位置 Fig. 1 Location of surface dust sampling sites in Suntuan mining area, Huaibei

1.2 样品前处理

使用实验室已建立的PACs的提取方法[35]：向玻璃试管中依次加入2 g无水硫酸钠(马弗炉400℃烧4 h备用)、2 g粒径在150~400目之间的地表尘样品(自然风干、研磨过筛后备用)、4.4 mL二氯甲烷和100 μL 10 μg ·mL-1的NAP-D8; 密封置于超声池中, 在不超过20℃的超声温度下超声5 h; 吸取上清液后离心; 经无菌型针式过滤器过滤后, 吸取900 μL置于样品瓶中; 向其加入100 μL 4 μg ·mL-1的定量内标, 涡旋后按仪器工作条件上机.

1.3 试剂与仪器

试剂：NAP-D8为前处理内标; 定量内标为ACE-D10、PHE-D10、CHR-D12和PER-D12; 16PAHs混标：萘(NAP)、蒽(ANT)、菲(PHE)、苊(ACE)、苊烯(ACY)、芴(FLU)、荧蒽(FLA)、芘(PYR)、苯并[a]蒽(BaA)、(CHR)、苯并[b]荧蒽(BbF)、苯并[k]荧蒽(BkF)、苯并[a]芘(BaP)、苯并[g, h, i]苝(BgP)、二苯并[a, h]蒽(DaA)和茚并[1, 2, 3-cd]芘(InP); 8种aPAHs标准品：1-甲基萘(1M-NAP)、1, 2-二甲基萘(1, 2M-NAP)、2-甲基蒽(2M-ANT)、2-甲基菲(2M-PHE)、3, 6-二甲基菲(3, 6M-PHE)、1-甲基芘(1M-PYR)、1-甲基(1M-CHR)和7-甲基苯并[a]芘(7M-BaP); 1种OPAHs标准品：9-芴酮(9-FLUO), 以上标准品均购自美国AccuStandard公司.试剂稀释均采用正己烷(色谱级, 北京百灵威科技有限公司); 萃取剂为二氯甲烷(质谱级, Thermal Fisher, USA); 干燥剂为无水硫酸钠(分析纯, 国药集团化学试剂有限公司).

仪器条件：气相色谱-三重四极杆串联质谱仪(Xevo TQ-GC, Waters, USA); DB-5MS型毛细管色谱柱(30 m×0.25 mm×0.25 μm).气相色谱条件：进样口温度为280℃, 进样模式为不分流进样, 载气为高纯氦气(纯度>99.999%), 流速为1 mL ·min-1. 色谱柱升温程序：70℃保持1 min、以15℃ ·min-1速度升温至180℃并保持2 min、以10℃ ·min-1速度升温至230℃并保持30 s、然后以5℃ ·min-1速度升温至250℃并保持2 min、最后以8℃ ·min-1速度升温至300℃并保持5 min.质谱条件：MRM模式, 离子源为电子轰击源(EI), 源温度为250℃, 电离能量为70 eV, 色谱与质谱接口温度为280℃.

1.4 健康风险评价

利用终生致癌风险(ILCR)模型计算当地儿童和成人通过手口摄入、呼吸吸入和皮肤接触这3种方式摄入16PAHs的致癌风险, 计算公式如下[36, 37]：

式中, CΣTEQ7PAHs为7种高致癌性16PAHs的BaP毒性当量之和(μg ·kg-1); CSF呼吸吸入、CSF手口摄入和CSF皮肤接触分别为3.85、7.30、25.0 (kg ·d ·mg-1); BW为体重(儿童和成人分别为16.2 kg和61.8 kg); ED为暴露年限(儿童和成人分别为6 a和30 a); EF为暴露频率(180 d ·a-1); AT为人均寿命(25 550 d); IR呼吸吸入为呼吸频率(儿童和成人分别为7.6 m3 ·d-1和20 m3 ·d-1); IR手口摄入为土壤摄取率(儿童和成人分别为200 mg ·d-1和100 mg ·d-1); SA为皮肤暴露面积(儿童和成人分别为2 800 cm2和5 700 cm2); AF为土壤的皮肤粘附因子(儿童和成人分别为0.7 mg ·cm-2和0.07 mg ·cm-2); ABS为皮肤吸附系数(0.1); PEF为颗粒排放因子(1.36×109 m3 ·kg-1).

1.5 质量控制与数据分析

本实验前处理内标NAP-D8的回收率在71.1% ~118.7%之间, 实验过程中每10个样品设置1针空白和1针平行样, 每20针样品设置1个基质加标样品.本实验中基质加标回收率在72.8% ~121.9%范围内, 平行样品标准偏差小于30%, 空白结果显示实验过程中未受到外界污染.MassLynx V4.1软件用于实验数据定量; Origin 2021用于数据分析及绘图; ArcGIS 10.2用于采样图及空间分布图的绘制; EPA PMF 5.0用于PACs的来源解析.

2 结果与讨论 2.1 地表尘中PACs的浓度与组成

孙疃矿区及周边地表尘中PACs含量差异较大(表 1), ΣPACs含量在283.8~36 852.5 μg ·kg-1范围内(均值4 114.2 μg ·kg-1).其中, Σ16PAHs含量在93.1~18 286.6 μg ·kg-1范围内(均值1 074.9 μg ·kg-1), 组成上以NAP和PHE为主; FLA、PYR、BaA和CHR次之; 其余组分虽有检出但含量较低.7种高致癌性PAHs均值为434.5 μg ·kg-1, 约占Σ16PAHs的40%.与其他矿区相比, 孙疃矿区地表尘中Σ16PAHs含量明显低于新疆准东煤矿(均值4 646.3 μg ·kg-1)[39]和内蒙古乌达煤矿(均值2 054.0 μg ·kg-1)[40], 与辽宁铁法煤矿(均值1 118.3 μg ·kg-1)[41]含量接近, 远高于重庆马家沟废弃煤矿(均值170.3 μg ·kg-1)[42].这可能是因为孙疃矿区煤种为我国稀缺的中灰、特低硫和特低磷的优质焦煤[43], 并且近年来环境治理工作取得成效.同时, 研究区范围较广, 涉及农田和居民区16PAHs含量较低.

表 1 PACs的含量、组成特征和毒性[38] /μg ·kg-1 Table 1 Concentration, composition characteristics, and toxicity of PACs/μg ·kg-1

ΣaPAHs含量为171.0~27 676.4 μg ·kg-1(均值2 593.8 μg ·kg-1), 这一数值约为Σ16PAHs的2.4倍, 占ΣPACs的63%以上, 说明aPAHs是当地PACs污染的主要贡献者.其中, aPAHs组成上以a-NAP和a-PHE为主; a-FLU和a-CHR含量较高; a-FLA、a-PYR和7M-BaP含量较低; 2M-ANT和a-ACE少有检出.同时, 萘和菲及其对应的烷基衍生物(C0~C5 NAP和C0~C4 PHE)在含量上呈现出先上升后下降的趋势, 即中间高两边低的“钟形”分布, Hindersmann等[44]将这种分布类型定义为成岩源, 由此推测该地区PACs主要受孙疃矿区煤炭开采影响.

二苯并呋喃(DBF)是油气勘探过程中典型的生物标志物, 在判别有机质沉积环境方面有着广泛应用[45].由于煤和石油同属化石燃料, 因此煤矿区周边地表尘中可能同样含有DBF.本研究中ΣOPAHs含量在19.6~3 971.4 μg ·kg-1范围内(均值445.6 μg ·kg-1), 这一数值虽远低于16PAHs和aPAHs, 但仍不容忽视.通过对孙疃矿区及周边地表尘中PACs的检测, 可以看出研究区PACs种类丰富且含量较高, 以往仅考虑16PAHs的污染特征具有一定的局限性, aPAHs和OPAHs同样存在严重的环境威胁.

16PAHs和aPAHs的环数组成情况如图 2所示.16PAHs中4环PAHs占比最高(38.5%), 2环(20.0%)和3环(27.2%)16PAHs次之, 5~6环PAHs占比最少.若按16PAHs的相对分子质量进行划分：相对分子质量低(47.2%)>相对分子质量中(38.5%)>相对分子质量高(14.3%), 而相对分子质量低的16PAHs主要来自成岩源, 煤和生物质燃烧主要产生相对分子质量中的16PAHs[46].因此, 推测当地不仅受矿区煤和煤矸石污染, 还受到居民区日常燃煤影响.aPAHs中由于a-NAP和a-PHE占主导地位, 相对分子质量低的aPAHs占比高达89.7%.结合16PAHs和aPAHs的含量及组成特征, 可以看出受煤矿影响的地区aPAHs含量较高.

(a)和(c)为16PAHs, (b)和(d)为aPAHs; 相对分子质量低的PAHs为2~3环PAHs, 相对分子质量中的PAHs为4环PAHs, 相对分子质量高的PAHs为5~6环PAHs 图 2 地表尘中16PAHs和aPAHs的环数组成 Fig. 2 Ring number composition of 16PAHs and aPAHs in surface dust

2.2 PACs的空间分布特征

孙疃矿区及周边地表尘中PACs的空间分布如图 3所示, 可知PACs污染范围较广, aPAHs相较于16PAHs和OPAHs污染程度更高.根据文献[47]提出的土壤中16PAHs污染等级标准, 孙疃矿区周边约61%的地表尘中ΣPACs达到重度污染水平; 22%的样品ΣPACs达到中度污染水平.其中位于西北部的样品(A62)中Σ16PAHs含量高达18 286.6 μg ·kg-1, 明显高于aPAHs(4 303.5 μg ·kg-1), 这可能是附近铁路交通及居民燃煤联合污染造成.其次, 矿区周边普遍存在用煤矸石铺路现象, 在煤矿开采与交通运输的联合影响下PACs污染严重.此外, 矿区东部的孙疃镇中心较为繁华, 在居民日常生活、交通尾气及矿区开采的影响下PACs污染水平较高.农田周边PACs的污染程度相对降低, 这可能和土地的翻种及农作物对PACs的吸收降解有关[48].从空间分布上看, aPAHs和OPAHs污染主要集中在煤矿区周边, 而16PAHs更易受周围环境影响, 说明aPAHs和OPAHs相较于16PAHs更适合作为煤矿区污染溯源的特征因子.

图 3 多环芳烃类化合物空间分布 Fig. 3 Spatial distribution of polycyclic aromatic compounds

2.3 地表尘中PACs的可能来源

PACs的来源解析通常依据16PAHs的特征比值[49, 50].本文选取FLA/(FLA+PYR)结合aPAHs比值对地表尘中PACs溯源, 并结合正定矩阵因子分解模型(PMF)判断各因子的贡献率.比值结果如图 4所示, 绝大部分地表尘样品FLA/(FLA+PYR) < 0.4, C0/(C0+C1)PHE+ANT < 0.5, 说明研究区主要受矿区开采过程中成岩源影响[51, 52]; 小部分呈现混合源或热解源特征, 说明可能受到居民日常燃煤和汽车尾气排放污染.此外, 多数样品C1-PHE/C0-PHE>2而呈成岩源特征[20].因此, 结合Σ16PAHs/ΣPACs、FLA/(FLA+PYR)、C0/(C0+C1)PHE+ANT以及萘和菲及其对应的烷基衍生物分布模式提出：当Σ16PAHs/ΣPACs < 0.25时主要受煤矿区污染, 并且PACs含量越高, 针对煤矿区PACs的比值评价指标效果越好[53].

C0表示对应的母体PAHs; C1表示一甲基取代PAHs 图 4 基于16PAHs与aPAHs的特征比值法 Fig. 4 Characteristic ratio method based on 16PAHs and aPAHs

PMF的运行结果如图 5所示, 因子1中PACs各组分浓度较高, 其中aPAHs占比最高, 且C0~C5 NAP、C0~C4 PHE在含量上呈“钟形”分布, 说明因子1与成岩源(煤和煤矸石颗粒)有关[44].此外, DBF及其烷基衍生物含量在因子1中占比较高, 说明DBF也是煤矿开采的重要标志物.因子2中16PAHs以NAP、ACE和ACY等2~3环为主, 其中, ACE是木材燃烧的主要成分[54]; FLA和PYR是生物质燃烧的典型指标[55, 56], 并且C0~C5 NAP呈“V型”分布[53], 因此推测因子2为生物质燃烧.因子3以FLA、PYR、BaA、CHR、BbF、BkF、BaP和InP为主, 由于煤炭燃烧主要产生3~4环16PAHs[57], 如BbF、CHR、PYR和BaP等.同时aPAHs、OPAHs含量和占比较低可能是因为16PAHs较其衍生物在热力学上更稳定, 高温燃烧过程中aPAHs和OPAHs被消耗[58], 因此推测因子3与燃煤有关.因子4中, 除低环的NAP、ACY、ACE、FLU和PHE外, OPAHs也占有一定比例, 而低环PACs和DBF通常与石油产品的泄漏和挥发有关[45, 59]; DBA是交通源的典型标志物[60], 因此推测因子4来源于交通污染和石油泄漏.矿区周边高速公路附近存在许多加油站, 并且煤矿运输和居民区日常交通过程中极易出现燃油泄漏现象.

1.NAP; 2.ACY; 3.ACE; 4.FLU; 5.PHE; 6.FLA; 7.PYR; 8.BaA; 9.CHR; 10.BbF; 11.BkF; 12.BaP; 13.InP; 14.DaA; 15.BgP; 16.C1-NAP; 17.C2-NAP; 18.C3-NAP; 19.C4-NAP; 20.C5-NAP; 21.C1-ACE; 22.C1-PHE; 23.C2-PHE; 24.C3-PHE; 25.C4-PHE; 26.C1-FLU; 27.C2-FLU; 28.C1-FLA; 29.C1-PYR; 30.C1-CHR; 31.7M-BaP; 32.9-FLUO; 33.DBF; 34.C1-DBF; 35.C2-DBF 图 5 各来源PMF的因子特征和贡献率 Fig. 5 Factor characteristics and contribution rate of PMF from various sources

结合PMF因子的贡献率可以看出, 孙疃矿区及周边环境地表尘中PACs污染主要来源于煤和煤矸石颗粒扩散, 占比高达47.3%.同时, 矿区周边堆积的煤矸石经过长期风化过程表面极易破碎化并随风扩散, 污染周边环境.其次是附近居民区日常生活中煤和生物质燃烧过程造成的PACs污染, 占比分别为14.6%和24.5%; 最后, 交通污染主要有居民日常交通和煤矿运输两部分组成, 并且过程中伴随着石油产品的挥发和泄漏, 占比为13.7%.因此, 应合理控制煤矿开采及运输过程中扬尘的扩散, 加大对废弃矸石堆的资源化利用以降低其对周围环境的污染.

2.4 地表尘中PACs的毒性和致癌风险评价

地表尘中PACs的毒性用BaP毒性当量含量(TEQBaP)表示, 计算结果示于表 1.ΣTEQ16PAHs在5.4~8 909.9 μg ·kg-1范围内(均值433.8 μg ·kg-1), ΣTEQaPAHs在0.2~578.0 μg ·kg-1范围内(均值为47.4 μg ·kg-1), 这一结果超过了荷兰土壤标准目标参考值(33.0 μg ·kg-1)[61], 其中贡献最大的主要来自7种高致癌性PAHs.尽管从计算结果看aPAHs毒性较低, 但以16PAHs的TEF计算aPAHs的毒性低估了aPAHs的风险, 且并未计算OPAHs的毒性, 实际多环芳烃衍生物的毒性更强.

ILCR计算结果如图 6(a)所示, 儿童ILCR在1.45×10-7~2.59×10-5范围内(均值1.54×10-6); 成人ILCR在3.41×10-8~6.11×10-6范围内(均值3.63×10-7), 明显低于儿童.结合USEPA在国家风险计划中划分的ILCR等级可以看出[62], 孙疃矿区及周边环境地表尘中16PAHs仅对儿童存在潜在致癌风险, 对于成人的致癌风险可以忽略不计. 无论是成人还是儿童, 皮肤接触均为PAHs进入人体的主要方式, 其次是手口摄入, 而呼吸吸入可忽略不计.尽管多环芳烃衍生物的致癌风险没有纳入计算, 矿区周边仍存在潜在风险.

(a)括号内数值和百分数表示通过3种方式造成的致癌风险和占比; (b)括号内数值和百分数表示4种污染源分别造成的致癌风险和占比 图 6 地表尘中16PAHs的致癌风险和污染源占比 Fig. 6 Carcinogenic risk of 16PAHs in surface dust and proportion of pollution sources

结合PMF的运行结果计算4种来源下儿童与成人的ILCR和占比, 利用PMF模型中7种高致癌性16PAHs代入ILCR公式进行运算.根据图 6(b)可以看出：儿童与成人污染源ILCR占比类似, 尽管成岩源是当地PACs的主要来源, 但燃煤ILCR占比最高(46%); 其次是成岩源(煤及煤矸石颗粒), ILCR占比高达24.2%; 生物质燃烧、交通源及石油产品的泄漏和挥发占比较小, 各占17.5%和12.3%.因此, 在治理矿区污染的同时, 应合理控制周边居民区及企业的燃煤, 推行环保节能的燃煤方式, 减少煤炭的不完全燃烧.

3 结论

(1) 淮北孙疃矿区地表尘中ΣPACs在283.8~36 852.5 μg ·kg-1范围内(均值4 114.2 μg ·kg-1); Σ16PAHs含量(均值1074.9 μg ·kg-1)约占ΣPACs的26%, 以中低环PAHs为主; ΣaPAHs含量(均值2 593.8 μg ·kg-1)占ΣPACs的63%以上, 组成上以烷基萘和烷基菲为主; ΣOPAHs含量较低(均值445.6 μg ·kg-1), 主要含有DBF及其烷基衍生物.因此, 除16PAHs外, 多环芳烃衍生物同样存在严重的环境威胁.

(2) 对比PACs污染的空间分布可以看出, 研究区内PACs影响范围较广, 且多环芳烃衍生物更适合作为煤矿污染溯源的指示物.此外, 煤矸石填埋道路附近存在严重的PACs污染, 应加大对煤矸石的资源化利用.

(3) 特征比值结果显示, 当Σ16PAHs/ΣPACs < 0.25时主要受煤矿区污染.PMF结果显示, 煤矿开采及煤矸石堆积为PACs的主要来源, 占比高达47.3%, 其次为煤和生物质燃烧, 交通源及石油产品泄漏的占比较低.

(4) 将ILCR与PMF相结合, 可以看出研究区内PACs污染已对儿童产生潜在风险.尽管成岩源是当地PACs的主要来源, 但煤及生物质燃烧对当地居民致癌风险最高(46%); 其次是煤及煤矸石污染, 交通污染及石油的挥发与泄漏风险最低.

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淮北孙疃矿区地表尘中多环芳烃类化合物的污染特征及致癌风险评价
徐振鹏, 钱雅慧, 洪秀萍, 罗钟庚, 高秀龙, 梁汉东