【作者】 邵莉；

【导师】 肖化云； 吴代赦；

【作者基本信息】 南昌大学 ， 环境工程， 2012， 博士

【摘要】 公路交通是环境中重金属污染物的主要排放源之一。公路重金属污染一直是国际环境地球化学高度关注的研究热点。由于受汽车排放等因素的影响,公路沿线大气颗粒物上重金属随着大气环流,在近地面大气、公路灰尘、路边土壤、绿化带及周围蔬菜中迁移、累积和转化,从而成为公路生态环境的一个潜在威胁,也成为地球大气环境恶化的一个重要因素。这类重金属物质对大气、土壤、水体造成的污染会直接或间接危害人体健康。到目前为止,采取了很多措施减少汽车尾气中污染物的排放,获得了不错的成效。但非尾气排放源仍然是交通活动重金属污染物的主要来源。本论文以昌九高速公路(赣粤高速公路南昌至九江段)、昌樟高速公路(赣粤高速公路南昌至樟树段)、温厚高速公路(沪昆高速进贤县温家圳至新建县厚田乡段)为研究对象,采集了昌九高速公路、昌樟高速公路沿线大气颗粒物,昌九高速公路、昌樟高速公路和温厚高速公路沿线道路灰尘和路旁表层土壤,测定了其中锌、铅、锰、铜、镉、锑的浓度,研究了高速公路沿线环境介质中锌、铅、锰、铜、镉、锑污染状况和分布规律,并探讨了车流量、天气及距公路距离等因素对重金属分布的影响,还对重金属的污染状况进行了评价。另外,还选择昌九高速公路两侧大气颗粒物、道路灰尘和土壤为研究对象,分析了其中铜、铅、锌、镉、锰和锑的形态分布特征,研究了高速公路两侧各环境介质中重金属的生物有效性。本文获得的主要结论如下：1.大气颗粒物、道路灰尘和土壤中重金属浓度从高到低呈现了相似的规律：Zn>Cu, Pb>Sb, Cd。大气颗粒物、道路灰尘和土壤中锌、铜、铅、锑和镉含量都与交通流量成正比,证明了这几种重金属的主要来源是交通活动。2.交通活动释放的锌主要来源于轮胎磨损,温度对轮胎磨损影响较大；虽然汽油中禁止添加铅,交通活动仍然继续向环境中释放铅,土壤中已积累的Pb将长期影响公路两侧土壤环境以及植物；道路灰尘和土壤中铜、锑的富集因子近似进一步说明了铜、锑具有相同来源,刹车片磨损被认为是铜、锑的主要来源；虽然道路灰尘和土壤中镉的浓度并不高,但与背景值相比,镉的污染非常严重,轮胎磨损是城市中锌和镉的主要来源；道路灰尘及土壤中锰主要来源于自然环境,大气颗粒物中锰应该主要来源于汽油中添加的锰基抗爆剂。3.大气颗粒物中锌、铅、锰、铜、镉和锑之间相关性很好,主要来源于交通污染；道路灰尘及土壤中铜、铅、锌、镉、锑的相关性较好说明了铜、铅、锌、镉、锑主要来源于交通活动。4.道路灰尘中重金属单项污染指数：Cd>>Zn、Cu>Sb>Pb,基本都处于重度污染水平。土壤中重金属单项污染指数从高到低依次为：Cd>Sb>Cu>Zn>Pb,镉、锑、铜属于重度污染,锌属于轻度到中度污染,铅处于尚清洁水平到轻度污染状况。公路旁环境介质中重金属污染风险等级：Cd>>Cu>Pb>Zn,镉的污染风险等级极强；铜的污染风险等级处于轻微到中等水平,铅、锌的污染风险等级基本处于轻微水平。5.公路旁环境介质中锌、铅、铜,镉和锑浓度随着车流量增加增加,证明了交通活动是这些重金属的主要来源。道路灰尘和土壤中锰含量与交通流量无关,证明了道路灰尘和土壤中锰的主要来源不是交通活动。6.交通路口停车-启动的行驶状态是影响交通污染水平的主要因素。收费站路面灰尘中锌的含量是行驶路段路面灰尘中锌的2.5倍；铜、铅、锑和镉在收费站和行驶路段的差别比锌小。7.雨天对公路两侧大气颗粒物中铅、锰、铜、镉、锑含量的影响不大。8.随着距离高速公路越来越远,各重金属浓度都有下降的趋势,但降低不多,这可能是因为这些重金属主要以PM10存在,迁移能力较好。铅、锑在乡村与在公路大侧大气中浓度相比,明显下降,这可能是因为铅、锑主要来源是交通源。其他金属可能有其他来源。9.在较大粒径和较小粒径大气颗粒物中锌、锰、铜的浓度都较高,铅、镉、锑主要存在于较小粒径大气颗粒物中。10.环境介质中铜主要以残渣态或有机物结合态存在；大气颗粒物中铅主要以酸可提取态存在,道路灰尘和路边表层土壤中铅主要以残渣态存在,这说明了大气颗粒物中铅来源于交通活动—汽车轴承摩擦、制动衬面摩擦,而道路灰尘、土壤中的铅主要来源于沉积在土壤中的铅；锌、镉在各环境介质中酸可提取态的比例都很高；锑很明显地主要以有机物结合态存在于各环境介质中；锰在大气颗粒物和道路灰尘、土壤中的存在形态也有明显的差别,大气颗粒物中锰主要以酸可提取态存在,道路灰尘和土壤中的锰以残渣态存在的比例明显增加,这些也说明了公路沿线环境大气颗粒物中锰主要来源于汽车尾气,而道路灰尘与土壤中锰受自然环境的影响很大。11.不同粒径大气颗粒物中重金属的化学形态组成没有明显区别,这些说明了大气颗粒物中重金属主要以PM10存在。较大粒径道路灰尘中以有机物结合态存在的重金属的比例显著增加,这说明了较大粒径灰尘中重金属主要来源于周围土壤颗粒。可能是因为接触时间较短的原因,雨水的冲刷作用对大气颗粒物中重金属的形态分布影响较小。12.根据连续提取法中可交换态、碳酸盐结合态与全量之间的比值来评价重金属元素的生物有效性,大气颗粒物中重金属生物有效性：锌>铅>锰>镉>铜,道路灰尘中重金属生物有效性：锌>镉>锰>铅>锑>铜,土壤中重金属生物有效性：锌>镉>锰>铅>铜>锑。锌、镉在各环境介质中的生物有效性都很高；铅在大气颗粒物和道路灰尘、土壤中的生物有效性差别很大,大气颗粒物中铅的生物有效性非常高,道路灰尘、土壤中生物有效性较低；铜、锑的生物有效性最低。重金属的潜在生物有效性,具有与生物有效性相同趋势。更多还原

【Abstract】 Traffic is one of the main source of heavy metal pollution, which has been an important issue in the field of environmental geochemistry. Due to vehicle emissions and other factors, heavy metals of atmospheric particulates near the surface in the microsystem along the urban road migrate, accumulate and transformate in the atmospheric near the ground, road dust, roadside soil, vegetables and the green belt with the atmospheric circulation. It has become a potential threat in the road ecological environment, and has become an important factor in the deterioration of the earth atmospheric environment. The pollution from heavy metals in the atmospheric, soil and water directly or indirectly endanger human health.This study identified the levels and sources of heavy metal contamination in airborne particles, road dusts and soils collected along three highways in Jiangxi Province with different traffic densities, and discuss the influence of traffic volume, driving conditions, weather and distance. A modified BCR three-step sequential extraction procedure in this article was adopted to study the possible chemical forms and the relative mobility and bioavailability of the heavy metals. The main conclusions of this study can be summed up as follows:1. Heavy metal concentrations in airborne particles, road dusts and soils presented similar rules:Zn>Cu、Pb>Sb、Cd. Manganese concentrations in road dusts and soils were in the range of the natural background value of soils in the Jiangxi area, and that in airborne particles was under zinc and lead, which suggested that airborne Mn came from traffic, and that Mn in road dusts and soils from background soil.2. Traffic-related Zn mainly come from the wear of tyre, and temperature was one of the main factors that influence the wear of tyres; although leaded petrol was banned, lead was still released from traffic to the environment; enrichment factors (EFs) of copper and antimony in road dusts and in soils were similar, which accounted further that copper and antimony had same source; although Cd concentrations in road dusts and soils were not very high, Cd pollution was very serious compared with background value. 3. Significant positive correlation between Pb and Zn, Cd, Cu and Sb concentrations in airborne particles, road dusts and soils suggested that those airborne metals mainly derived from traffic. Correlations between atmospheric Mn and Cu, Pb, Zn, Cd and Sb concentrations were far better than that between Mn and Cu, Pb, Zn, Cd and Sb concentrations in road dusts and soils, which suggested that airborne Mn came from traffic, and that Mn in road dusts and soils from background soil.4. There was no linear relationship between Mn concentrations and traffic volume, while there were strong linear relationships between Zn, Cu, Pb, Sb and Cd concentrations and traffic volume, which reflected that traffic was not the main source of Mn in road dusts and soils, and was the main source of Zn, Cu, Pb, Sb and Cd.5. Stop-start driving conditions injunctions were thought to be a major factor in the relationship of traffic to metal pollution levels.6. There was just a little decline of Pb, Mn, Cu, Cd and Sb concentrations when raining. It was likely because automotive exhaust or metal wear/corrosion were the main sources of these metals, which were hardly subject to weather. When raining atmospheric Zn concentration in PM10increased regardless of rain wash, which can be explained by the fact that the particles from tyre wear will become smaller due to the decreased frictional force when raining, and rain wash had a little effect on PM10.7. Heavy metal concentrations showed a little decreasing trend with increasing distance from the road, which can be explained by the fact that heavy metals mainly existed in PM10moving more easily.8. The values of the contamination factor of the road dust decreased in the following order:Cd>>Cu, Sb, Zn>Pb, while the results of soils reflected similar patterns. Ecological risks of road dusts and soils were in order Cd>>Cu>Pb>Zn. These results show extreme high ecological risks of Cd except of soils near WH highway which corresponded to very high ecological risk, and low ecological risks of Cu, Pb, Zn.9. The chemical association of Cu within airborne particles, road dusts and soils was dominated by the the organic and residual fraction. The chemical association of Pb in airborne particles was dominated by the acid soluble/exchangeable, and that in road dusts and soils was dominated by the residual. The chemical association of Zn within airborne particles, road dusts and soils were all dominated by the acid soluble/exchangeable phase. The chemical fraction of Cd in airborne particles, road dusts and soils were all dominated by the acid soluble. The chemical fraction of Sb in road dusts and soils were both dominated by the organic. Considering the acid soluble phase, the order of bioavailability in airborne particles decreased in the following order:Zn>Pb>Mn>Cd>Cu, in road dusts:Zn>Cd>Mn>Pb>Sb>Cu, and in soils: Zn>Cd>Mn>Pb>Cu>Sb.更多还原