運用水匱乏方法學評估臺灣生乳生產之潛在淡水環境衝擊

為使臺灣乳業發展與淡水環境永續間取得平衡，有必要評估生產活動對淡水環境產生之衝擊，釐清二者因果關係。本研究依照 ISO 14046 對新竹縣 5 場乳牛場之生乳生產過程進行盤查，盤查時間為 2018 年 5 月至 2019 年 4 月，系統邊界為「搖籃至大門」，功能單位為 1 kg 乳脂肪與乳蛋白校正乳 (Fat and Protein Corrected Milk, FPCM)，以建立之模式與係數為基礎，運用水匱乏 (Water Scarcity)方法學評估其於當地及其他縣市生產時，對壓力加權水匱乏足跡 (stress-weighted Water Scarcity Footprint, WSF)的貢獻，並評估水匱乏生產力 (Water Scarcity Productivity, WSP)，據以歸納改善策略。結果顯示，平均生產 1 kg FPCM 將消耗27 ± 7 L 的水；臺灣 16 個縣市之水資源緊迫指數 (Water Stress Index, WSI)為 0.05～1；stress-weighted WSF 之結果為 2.2～44.8 L H2Oeq/kg FPCM；WSP 之結果為0.037～0.749 kg FPCM/L water。於臺北市、桃園市、臺中市、彰化縣及雲林縣生產 1 kg FPCM 時，對淡水環境之衝擊相當於消耗 44.8 L 的水，WSP 僅 0.037 kg FPCM/L water (WSI = 1)；於南投縣或嘉義縣生產而產生之衝擊則僅相當於消耗2.2 L 的水，WSP 則高達 0.749 kg FPCM/L water (WSI = 0.05)。於水資源緊迫程度低之區域進行生產活動，有助於減緩對淡水環境之衝擊，而基於水資源運用與生乳生產無法脫鉤，改善WSP 可能比改善 stressed-weighted WSF 更具方向性。提高生乳生產效率或限制乳牛場至 WSI 高之區域設置，可能具有減緩對淡水環境衝擊之潛力，未來若有更精準之時空間尺度資料，並探討其他環境機制時，有助於制定更完善的產業發展策略。

關鍵字

水匱乏；環境衝擊；生乳；永續性

並列摘要

In order to achieve a balance between the development of Taiwan dairy industry and the sustainability of the freshwater environment, it is necessary to assess the impact of the production on the freshwater environment and clarify the causal relationship between the two. In this study, five dairy farms in Hsinchu County were inventoried in accordance with ISO 14046, from May 2018 to April 2019. The system boundary was "cradle to gate". Functional unit was 1 kg of fat and protein corrected milk (FPCM). According to the established model, use the methodology of Water Scarcity assess the contribution to stress-weighted Water Scarcity Footprint (WSF) when producing in local and other counties and cities, and assess Water Scarcity Productivity (WSP). Then summarize the improvement strategies. The results show that the average production of 1 kg of FPCM consumed 27 ± 7 L of water; the Water Stress Index (WSI) of 16 counties and cities in Taiwan was 0.05−1; the result of stress-weighted WSF was 2.2−44.8 L H2Oeq/kg FPCM; the result of WSP was 0.037−0.749 kg FPCM/L water. When producing 1 kg of FPCM in Taipei City, Taoyuan City, Taichung City, Changhua County, and Yunlin County, the impact on the freshwater environment was equivalent to consuming 44.8 L of water, and WSP was only 0.037 kg FPCM/L water (WSI = 1). The impact conducted by production in Nantou County or Chiayi County was equivalent to consuming 2.2 L of water, and WSP was as high as 0.749 kg FPCM/L water (WSI = 0.05). Production activities in areas with low water stress can help mitigate the impact on the freshwater environment. The consumption of water cannot be decoupled from raw milk production, improving WSP may be more directional than improving stressed-weighted WSF. Improving production efficiency or restricting dairy farms to high WSI region may have the potential to mitigate the impact on the freshwater environment. A more accurate study of space-time data and other environmental mechanisms will lead to the formulation of a more complete industrial development strategy.