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题名: 典型区域全氟烷基酸多介质传输与风险评价
作者: 刘朝阳1
学位类别: 博士
答辩日期: 2017-05
授予单位: 中国科学院大学
授予地点: 北京
导师: 吕永龙
关键词: PFAAs,污染途径,排放估算,作物富集,风险评价 ; PFAAs ; pollution pathway ; release estimation ; crop bioaccumulation ; risk assessment
其他题名: Multimedia Transport and Risk Assessment of Perfluoroalkyl Acids in Typical Regions
学位专业: 环境科学
中文摘要: 全氟烷基酸(PFAAs)在工业和生活产品中应用广泛,并作为一类新型污染 物被各国政府、工业界和学术界普遍关注。我国目前已成为 PFAAs最主要的生 产和消费国,不可避免地导致大量 PFAAs排放到环境中。本文针对我国 PFAAs 排放控制与监管需求,以使用量最多的全氟辛烷磺酸(PFOS)和全氟辛酸(PFOA) 为代表,通过系统运用源排放数据和传输参数,分析了其环境污染途径,估算了 不同途径的环境污染释放量。同时选择位于环渤海南部的大型氟化工园区为典型 污染源,通过采集周边 10km范围内地下水、地表水、土壤、降水和农作物等样 品并测定其 PFAAs浓度,进一步探讨了重要工业源周边多环境介质中 PFAAs的 污染模式、传输特征和生态风险,研究了当地小麦和玉米中 PFAAs的赋存水平 和富集规律,结合居民饮食习惯评价了潜在健康风险。 研究表明我国环境中 80-90%的 PFOS和 PFOA排放来源于其制造与使用企 业,其中大部分以工业废水的形式进行排放。除工业废水外,PFOS还主要来源 于泡沫灭火剂(AFFF)和氟虫胺类农药的使用。生活污水、工业废气和垃圾填埋 是继工业废水之后我国环境中 PFOA的最主要来源。工业废水排放是地表水中 PFOS和 PFOA最主要的污染途径。除此之外,地表水中 PFOS污染还主要源于 AFFF大量使用后的溢流,PFOA污染主要源于生活污水排放和降水径流。土壤 中大部分 PFOS污染归因于 AFFF和农药使用后的下渗,而 PFOA污染主要与大 气沉降和垃圾渗滤液有关。地表水渗流和土壤淋溶是地下水中 PFOS和 PFOA的 最主要污染途径。大量野外监测数据也证实了工业废水、垃圾渗滤液和 AFFF的 使用是我国环境中 PFOS和 PFOA的主要来源,常导致一系列局部污染热点。大 部分降水样品中 PFOA浓度高于 PFOS的现象也间接佐证了大气中 PFOA较高 的排放量。基于上述结果,我们发现降低我国 PFOS和 PFOA污染的最有力举措 是控制工业排放,特别是工业废水排放。 氟化工园区周边地下水、地表水、农田土壤和降水中均检测到了 12种目标 PFAAs,其中 PFOA是最主要的组分,其次是一些短链的全氟羧酸(PFCAs),这 种组分构成与氟化工园区工业过程密切相关。随着与氟化工园区距离的增加,这 些介质中 PFAAs浓度均呈现先急剧下降后缓慢降低的指数下降趋势。污染热点 发生在氟化工园区周边 1km范围和废水排放的下游区域,地下水、地表水、农 田土壤和降水中的最高浓度分别为 273 μg/L、1.86mg/L、641ng/g和 4.86μg/L, 所有这些值与已报道的相应介质中 PFAAs浓度相比均处于最高值。 氟化工园区与接收其废水的东猪龙河对浅层地下水的污染范围至少为 4km和 3km。距离氟化工园区 1km和受污河流 1.5km范围内的地下水中 PFAAs浓度 远高于相关饮用水质量标准,直接饮用会导致潜在健康风险;受 PFAAs重度污 染的河流也可能产生潜在水生生态风险。地下水中 PFAAs污染主要来源于两种 途径:(1)PFAAs通过工业废水排放到地表水中,再进一步渗流到附近地下水中; (2)PFAAs通过大气排放和沉降到达地面,并进一步淋溶到地下水中。地下水 中 PFAAs衰减过程主要与扩散稀释和含水层固体吸附有关。由于短链 PFCAs较 高的移动性与较低的吸附性,在地表水渗流以及地下水扩散过程中这些组分所占 比例呈上升趋势,而 PFOA的相对比例逐渐降低。 土壤中 PFAAs污染主要源于灌溉水和大气沉降,氟化工园区对周边土壤的 污染距离至少为 10km。一些高浓度的 PFAAs已超过相应生态风险评价阈值,可 能会对当地土壤生物造成潜在威胁。土壤与灌溉水中 PFAAs浓度的对数值呈线 性相关,灌溉水中长链组分更容易吸附到土壤颗粒上。氟化工园区附近降水中 PFAAs处于极高水平,平均浓度达 2.27μg/L,但在 5km范围内明显降低。 小麦和玉米籽粒中也均检测到了 12种 PFAAs组分。由于富集倾向性,短链 PFCAs(C4-C7)特别是全氟丁酸(PFBA)(C4)成为籽粒中 PFAAs的主要组分。 氟化工园区 10km范围内种植的小麦和玉米均受到不同程度 PFAAs污染,小麦 和玉米籽粒中 PFAAs的浓度范围分别为 1.13ng/g-480ng/g和 0.7ng/g-58.8ng/g。 籽粒中 PFAAs的污染热点位于氟化工园区周边 1km范围和受污染的东猪龙河沿 岸区域,并随着与这些污染源距离增加也呈现类似指数下降的趋势。 小麦和玉米籽粒的富集能力随着 PFAA组分碳链的延长,呈逐渐降低的趋 势。PFAA每增加 1个碳链长度,其富集系数对数值下降 0.5个单位。小麦籽粒 PFAAs富集系数比玉米籽粒 PFAAs富集系数高约 11.6倍,这可能归因于小麦相 比于玉米含有更高的蛋白质含量。土壤与籽粒中主要 PFAA组分的浓度对数值呈 线性正相关,表明土壤 PFAAs浓度对作物富集有重要影响。通过食用受污染的 小麦和玉米导致的 PFAAs人体暴露可能会对当地居民产生潜在健康风险,尤其 是对幼儿和儿童。
英文摘要: Perfluoroalkyl acids (PFAAs) are widely used in industrial and household products, and have attracted broad attention from government, industry and academia as a class of emerging persistent organic pollutants (POPs). China has gradually become the most important manufacturing and consumption center of PFAAs, and inadvertently become the world’s major contamination hotspots. Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are two of the most widely used PFAAs in China. For effectively emission control and regulatory of PFAAs in China, this study takes PFOS and PFOA as representative components to systematically analyzed their pollution pathways in the environment, and further combined source emission data with related transport parameters to estimate release amounts of these chemicals through different pollution pathways. Furthermore, we chose a mega fluorochemical industrial park (FIP) located in South Bohai Rim as a typical source, and then collected and detected samples including groundwater, surface water, soil, precipitation and crops within a 10 km radius of the FIP to systematically explore contamination pattern, transport pathways and ecological risk of PFAAs in surrounding multi-media. Besides, occurrence and bioaccumulation of PFAAs in local wheat and maize grains were also studied and combined with local eating habits to assess potential health risks for residents caused by PFAAs pollution. The study results indicated that about 80-90% of PFOS and PFOA contamination in the Chinese environment was estimated to come directly from manufacturing and use facilities mostly via industrial wastewater discharge. The other major contamination sources of PFOS were screened to be aqueous fire-fighting foams (AFFF), and pesticides containing sulfluramid. For PFOA, following up industrial wastewater, were industrial exhaust gas, domestic wastewater and landfill leachate as contamination sources. For surface water contamination, the major pollution contributors after industrial wastewater were AFFF spill runoff for PFOS, and domestic wastewater and precipitation-runoff for PFOA. The majority of PFOS that contaminated soil was considered to be associated with infiltration of AFFF and pesticides, while most PFOA in soil was attributed to atmospheric deposition and landfill leachate. Surface water seepage and soil leaching are two dominant pollution pathways of PFOS and PFOA in groundwater. Areview of the available monitoring data for PFOS and PFOA in the field confirmed industrial wastewater, landfill leachate and AFFF application as important sources, which may cause local contamination hotspots. Higher concentrations of PFOAthan PFOS found in precipitation also corroborated the prediction of more PFOA release into air. To reduce PFOS and PFOA contamination of the Chinese environment the focus for control should be on industrial emissions, especially wastewater discharge. Each of 12 target PFAAs was detected in groundwater, surface water, agricultural soil and precipitation around the FIP. Among 12 detected PFAAs, PFOA was dominanted, followed by shorter-chained perfluoroalkyl carboxylic acids (PFCAs). As the distance increased from the FIP, PFAAs levels in all these media showed a sharp initial decrease followed by a more gentle decline. Contamination hotspots of PFAAs were found within 1km from the FIP and along the Dongzhulong River, which received wastewater discharged from the FIP. The maximum concentration of PFAAs detected in groundwater, surface water, agricultural soil and precipitation were 273 μg/L, 1.86mg/L, 641ng/g and 4.86μg/L, and all these values were highest compared with reported PFAAs concentrations in previous studies. The contamination signal from the FIP site on PFAAs in groundwater existed within a radius of 4 km, and at least 3 km from the polluted Dongzhulong River. PFAAs concentrations in groundwater within a radius of 1 km from the FIP and within a distance of 1.5 km along the river exceed current available standards for drinking water; while extremely high levels of PFAAs in local contaminated river may also result in potential aquatic ecological risk. The dominant pollution pathways of PFAAs included (i) discharge into surface water then to groundwater through seepage, and (ii) atmospheric deposition from the FIP, followed by infiltration to groundwater. The major controlling factor in PFAA attenuation processes was likely to be dilution together with dispersion and adsorption to aquifer solids. Due to a greater mobility and a lower adsorption affinity for short-chain PFCAs (C4-C6), the proportion of these chemicals increased while those of PFOA (C8) declined during surface water seepage and further dispersion in groundwater. The soil contamination was associated with the presence of PFAAs in irrigation water and precipitation. Elevated PFAA concentrations in soil were still present within a radius of 10 km of the FIP. Some high concentrations of PFAAs in agricultural soil near the FIP and along the heavily polluted Dongzhulong River had exceeded the ecological risk assessment threshold, indicating a potential threat to soil organisms. For several main PFAA components, there was a significant linear positive correlation between the logarithm (log10) of concentrations in agricultural soils and corresponding irrigation water. Longer-chained PFAAs in irrigation water were more susceptible to adsorption to soil particles. For precipitation, unprecedented levels of PFAAs were found immediately near the FIP with an average concentration of 2.27μg/L, although they decreased significantly beyond 5km. Each of 12 target PFAAs was also detected in local wheat and maize grain. Due to bioaccumulation preference, short-chain PFCAs, especially perfluorobutanoic acid (PFBA), became the major PFAA contaminants in grains of wheat and maize. A pollution signal from the FIP could be found as far away as 10 km within cereals with concentrations ranging from 1.13ng/g-480ng/g in wheat grain to 0.7ng/g-58.8ng/g in maize grain. High levels of PFAAs also occurred within 1km from the FIP and along the seriously polluted Dongzhulong River. With the increasing distance from these sources, the concentrations of PFAAs also decreased with an exponential trend. The bioaccumulation factors (BAFs) for both grains showed a decrease with increasing chain length of PFAAs (approximately 0.5 log decrease per CF2 group). Compared to maize grain, wheat grain showed higher BAFs, possibly related to its higher protein content. The PFCA (C4-C8) concentrations (on a log10 basis) in agricultural soil and grain were found to show a linear positive correlation, indicating soil concentrations of PFAAs was an important influencing factor on crop bioaccumulation. Local human exposure of PFAAs via the consumption of contaminated grains represents a health risk for local residents, especially for toddlers and children.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/38662
Appears in Collections:城市与区域生态国家重点实验室_学位论文

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