城市积尘重金属累积-冲刷规律与风险研究

发布时间：2018-05-17 04:17

本文选题：城市积尘 + 重金属　；参考：《清华大学》2015年硕士论文

【摘要】：本研究以城市积尘重金属(Cr、Cu、Ni、Pb和Zn)为研究对象,开展重金属累积过程与模型研究,对比分析不同材料硬化表面积尘重金属累积规律差异,评估积尘潜在生态风险与健康风险,考察典型功能区与下垫面重金属冲刷规律,核算示范区重金属年产污负荷总量,并评估生态风险。城市积尘重金属累积过程研究发现,商业区、工业区、居民区重金属各粒径范围颗粒物携带重金属比例相对稳定,其中75μm细颗粒物是重金属的主要载体。模型拟合发现,幂指数模型能较好地模拟城市各功能区重金属累积过程,干期天数达到10天时,累积过程基本完成。城市典型硬化表面积尘重金属研究发现,重金属浓度表现为:墙面屋面路面,重金属负荷与之相反。形态分析表明Zn的可移动态比例明显高于其他重金属;潜在生态风险评估发现,彩钢瓦屋面与沥青路面均表现出高度生态风险;重金属非致癌风险评估发现,彩钢瓦屋面积尘中Pb、Cr和沥青路面积尘中Pb对儿童非致癌风险均高于安全限制1,构成威胁,须加以控制。重金属Cr和Ni致癌风险评价发现,城市积尘不存在致癌风险;改进城市尺度积尘重金属潜在生态风险与健康风险评价模型对示范区域开展评价,示范区域潜在生态风险为401.2,属于较高生态风险,示范区域积尘重金属Pb非致癌风险明显高于其他重金属,但尚不构成威胁。Cr和Ni的致癌风险评价表明,该区域不存在致癌风险。城市积尘冲刷规律研究表明,不同下垫面径流重金属浓度表现为:道路绿地屋面庭院硬化下垫面;不同功能区径流重金属浓度表现为:商业区居民区工业区;冲刷过程中,不透水下垫面表现为迁移限制型冲刷,而透水下垫面则表现为来源限制型冲刷;径流中颗粒物对降雨中溶解态重金属Cu和Zn具有明显的吸附作用;SS与各重金属相关性较好,可作为城市径流重金属的替代性指标;结合示范区径流冲刷规律,可将示范区初期雨水定为4mm。构建累积-冲刷联合模型对示范区重金属年产污负荷进行核算,示范区域重金属Cr,Cu,Ni,Pb和Zn产污负荷分别为97.8 kg/a,112.6 kg/a,29.6 kg/a,181.8kg/a和723.4 kg/a;道路是示范区内重金属的主要来源,占比为58%,其次为庭院硬化地表和屋面,绿地产污负荷最低,仅占4%;生态风险评估发现,全年径流存在较高生态风险。
[Abstract]:In this study, the accumulation process and model of heavy metals were studied, and the differences of heavy metal accumulation in different materials were compared and analyzed, and the potential ecological risk and health risk of dust accumulation were evaluated. The rules of heavy metals scouring in typical functional areas and underlying surfaces were investigated, the total annual pollution load of heavy metals in the demonstration area was calculated, and ecological risk was evaluated. The study on the accumulation process of heavy metals in urban dusts showed that the proportion of heavy metal carrying heavy metals was relatively stable in the grain size range of heavy metals in commercial, industrial and residential areas, and 75 渭 m fine particles were the main carriers of heavy metals. The model fitting shows that the power exponent model can simulate the accumulation process of heavy metals in various functional areas of the city. When the dry days reach 10 days, the accumulation process is basically completed. It is found that the concentration of heavy metals in urban typical hardened surface dust is as follows: the wall roof pavement, and the heavy metal load is opposite to it. Morphological analysis showed that the ratio of movable Zn to other heavy metals was significantly higher than that of other heavy metals. The potential ecological risk assessment showed that both the roofing and asphalt pavement of Caigang steel showed high ecological risk, while the non-carcinogenic risk assessment of heavy metals found that, The PbCU Cr in the roof dust of colored steel tile and Pb in the dust deposition of asphalt pavement are both higher than the safety limit for children, which is a threat and should be controlled. The carcinogenic risk assessment of heavy metals Cr and Ni showed that there was no carcinogenic risk in urban dust accumulation, and the evaluation model of potential ecological risk and health risk of heavy metals in urban scale dust accumulation was improved to evaluate the demonstration area. The potential ecological risk of the demonstration area is 401.2, which belongs to the higher ecological risk. The non-carcinogenic risk of the dust accumulation heavy metal Pb in the demonstration area is obviously higher than that of the other heavy metals, but the carcinogenic risk assessment of the risk of carcinogenesis does not show that there is no carcinogenic risk in this region. The results of urban dust scour show that the concentrations of heavy metals in runoff of different underlying surfaces are as follows: road greenbelt roofing courtyard hardened underlay surface; runoff heavy metal concentrations in different functional areas are as follows: commercial district residential area; scour process; The impermeable underlying surface is characterized by migration limited erosion, while the permeable underwater surface is characterized by source-limited scour, and particles in runoff have obvious adsorption on dissolved heavy metals Cu and Zn in rainfall. SS has a good correlation with each heavy metal. It can be used as an alternative index for heavy metals in urban runoff, and Rain Water can be determined as 4mm at the initial stage of the demonstration area in combination with the runoff erosion law in the demonstration area. A combined cumulation-scour model was established to calculate the annual pollution load of heavy metals in the demonstration area. The pollution load of the heavy metals, Cr-CuCuN, Nibb, Pb and Zn in the demonstration area was 97.8 kg / a and 112.6 kg / a, respectively, 29.6 kg / a and 181.8 kg / a and 723.4 kg / a, respectively, and the road was the main source of heavy metals in the demonstration area. The proportion was 58, followed by the hardened surface and roof of the courtyard, and the pollution load of green real estate was the lowest, accounting for only 4. The ecological risk assessment showed that the annual runoff had higher ecological risk.
【学位授予单位】：清华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X513

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