以存匯觀點探討都市危害物質之管理，以台北市鉛物質為例

A Sink Perspective for Managing Hazardous Materials- a Case Study of Pb in Taipei City

陳思蓉(Sih-Rong Chen)

指導教授 ： 馬鴻文

國立臺灣大學/工學院/環境工程學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201601886

摘要

都市有許多的環境問題，而且問題往往都發生在都市的存匯(sinks)，因為存匯是物質的聚集之處。都市代謝(Urban metabolism)可以針對都市中的物質進行流布分析幫助我們瞭解問題的源頭，所以若要解決都市的環境問題必須瞭解都市存匯的功能特性，因為這些特性會衍生出不同的環境議題。然而，無論是什麼環境議題，都是為了要尋找物質「合適的存匯」，本研究以有害人體健康的物質為例，認為危害物質合適的存匯應該是同時考量「人為存匯(anthropogenic sinks)對物質的處理能力」以及「物質在環境存匯(environmental sinks)所產生的健康風險」。物質流分析(Material flow analysis, MFA)是一種系統評估工具，它可以全面地掌握某物質在都市中相關的程序與流量；而健康風險評估(Health risk assessment, HRA)則可以量化這些流量造成健康衝擊的程度，本研究整合物質流分析與健康風險評估，用來評定危害物質在都市人為存匯的合適性，以及評估物質代謝後所造成的環境衝擊；前者可幫助我們辨識都市處理危害物質的狀況，後者可以讓我們檢討物質的流動是否還有改善空間。以台北市鉛物質為案例，評比除了「回收」與「掩埋場」之外，焚化爐、底渣再利用、堆肥、污水廠及污泥再利用等 5 種人為存匯對鉛的合適性，研究結果顯示，「焚化爐」是當中最合適的人為存匯，因為它將大部分的鉛捕捉下來成為灰渣；而「污水廠」是最不適合的，由於台北市河川的單位排放鉛風險較大，故建議污水廠應注意鉛在其放流水的流量。本研究雖然評估鉛的都市代謝危害商數(HQ)為 0.15、致癌風險(CR)為 6.1E-08，但並不能只與傳統的可接受風險比較，還要作為都市鉛管理的參考。為了能從源頭減少台北市鉛風險，依照台北市廢棄物現況設計政策情境，其中「降低一般垃圾中塑膠類的垃圾量，但仍達到全國平均低位發熱量」所減少的鉛風險最顯著；但若要兼顧提昇經濟效益與降低環境衝擊，「達到資源回收率 65%，超過新加坡、韓國、德國的回收率」更是理想的狀況。

關鍵字

都市代謝 ； 存匯 ； 物質流分析 ； 健康風險評估 ； 鉛

並列摘要

There are many environmental problems in the city, and the root of these problems are sinks where materials gather to. Urban metabolism helps us to understand the source of the problem by analyzing the flows of material. To solve the environmental problems in the city, the functions and characteristics of the sinks needs to be investigated because these characteristics would cause different environmental issues. No matter what kind of environmental issues, scientists aim to find the appropriate sinks for materials. For hazardous materials, "the ability of anthropogenic sinks" and "the capacity of the environmental sinks" should be taken into account at the same time. Material flow analysis (MFA), a systematic assessment tool, which gives rise to a holistic view of the related processes and the flows of certain materials within a city. Health risk assessment (HRA) is used to quantify the extent of health impactions caused by these flows. The MFA and HRA are integrated in this study to assess the appropriateness of harmful materials in urban anthropogenic sinks and to evaluate the environmental impact of urban metabolism. MFA is exployed to decide the appropriate treatment for harmful materials, while HRA provides the suggestion to improve material usage. Take lead materials in Taipei city as an example, the comparison and the assessment of lead materials were investigated among five different anthropogenic sinks including incinerator, bottom ash reuse, compost, wastewater treatment and sludge reuse. The result indicates that the incinerator is the most appropriate choice among these sinks because it captures most of lead and turn it into bottom ash. In contrast, the wastewater treatment is the least appropriate one because the effluent still contains lead. Although the hazard quotient is 0.15 and the cancer risk is 6.1E-08, both below the acceptable level, we only adopt these value as the reference information to manage lead in the city. In order to reduce the risk of lead from the pollution source, we design the policy scenarios based on the current situation in Taipei city. The scenario of "reduce the plastic in the garbage but still reach the lower calorific value" shows the most significantly reduced risk of lead. Moreover, the scenario of "reach the 65% recovery rate and surpass Singapore, Korea and Germany" could be a better choice, which not only decreases environmental impact but also increases the economic benefit.

並列關鍵字

Urban metabolism ； Sink ； Material flow analysis ； Health risk assessment ； Pb

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