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年度	109	專案性質	實驗性質
專案類別	研究專案	研究主題	調查
申請機構	國立臺灣大學	申請系所	生物環境系統工程學系
專案主持人	潘述元	職等/職稱	助理教授
專案中文名稱	建立水田中土壤重金屬質量平衡模式
中文關鍵字	累積, 銅, 桃園, 物質流, 改善策略
專案英文名稱	Establishment of Mass Balance Models for Heavy Metals in Paddy Soils
英文關鍵字	Accumulation, Copper, Taoyuan, Material Flow, Improvement Strategy
執行金額	1,150,000元
執行期間	2020/1/30 至 2020/12/4
計畫中文摘要	造成水田中土壤重金屬累積因子相當多，包括：灌溉引水、大氣落塵、肥料使用等。國際上，許多研究團隊已針對水田中各種重金屬之傳輸宿命進行研析，但國內仍鮮少有研究針對水田重金屬累積進行系統性之分析。本計畫於桃園區域選定代表性已復育完成之水稻田兩處，分析關鍵生物環境系統界面（例如：水、土壤、作物及空氣）內所含銅金屬之濃度，建立銅金屬質量平衡模式，推估水田土壤重金屬累積超標年限；同時，已於十月召開兩場次專家諮詢會議，邀請十位國內專家學者，共同研擬機構面、法規面、技術面及財務面上之改善策略及行動方案，以供環保署未來施政參考依據。 本研究將針對水田中關鍵生物環境系統界面，包括：灌溉水（含懸浮固體）、表層土壤、作物、肥料使用、大氣落塵等，進行現地調查及採樣，分析其所含銅金屬之濃度。分析兩農地中2020年第1期稻作之總銅輸入為143.0及364.4 mg/m2主要的重金屬輸入為灌溉水（96.2%及98.8%），而收割稻作約可造成重金屬移除達輸入之8.2%及4.9%；銅金屬累積於土壤之速率為0.67‒1.68 mg/kg/yr。土壤分析結果顯示農地1及農地2之表土銅濃度近溝渠側達193‒222 mg/kg及171‒282 mg/kg，而較遠離溝渠側之樣本達47‒103及46‒79 mg/kg。根據輸入率及現在的土壤銅濃度，推測最快可能於2043年達到食用農地監測標準。 結果顯示重金屬累積相當顯著，於水田管理時，應考慮重金屬輸入和輸出，進而研擬防治方案與風險評估。本研究之結果，顯示推動跨部會合作機制之重要性，可整合、建置資訊系統，分享河川及灌溉渠道之底泥及灌溉水質資訊。配合調查、研擬及分析整治之準則、預警值及應對方法，以確保農地生產環境之安全。加強推動灌排分離，避免產業污染影響下游灌溉水質；並瞭解上游產業分佈，進而平行推動上、下游之污染防治；完善國土計畫法與工輔法之推動，降低土壤污染之潛在風險。在模式建立上，應考慮土壤性質（例如有機質、無定型鐵鋁、pH值等）、重金屬在土壤內、植體內、水田間傳輸的異質性和宿命進行採樣及分析。應針對田間進出水之流量（例如管流式電子流量計）、金屬濃度建立即時監控系統，以提升數據品質與模式預測之精確度。在實務上，建議評估節水農法（例：再生稻、乾溼交替灌溉法）在土壤之永續利用策略之可行性；未來啟動整治技術時，應整合循環經濟之精神，考量以綠色永續科技，進行底泥之再利用、施加生物炭進行重金屬污染之整治。提供適當補助或經濟誘因，鼓勵於農地休耕時，種植易吸收重金屬之作物，以延長土壤安全年限，並確保糧食安全。針對前述之生物炭施加、節水農法的應用提供獎勵和相對應補償策略。
計畫英文摘要	Several factors, such as irrigation water, atmospheric deposition, and fertilizers, result in the accumulation of heavy metals in paddy soils. Although extensive studies on this issue have been carried out worldwide, little to none study systematically analyzes heavy metal fate in paddy soils in Taiwan. This project selected two remediated paddy fields (Field-1 and Field-2) in Taoyuan and analyzed the distribution and fate of copper in paddy fields. The main scope is determining the concentrations of copper in key bioenvironmental factors (e.g., water, soil, plant and air deposit) of paddy field, followed by establishing of mass balance models and estimating the year of Cu excessing relevant regulations. This project also organized two Ad-Hoc committee meetings to propose the strategies and action plans from the aspects of institution, regulation, technology and finance for establishing remediation plan. We sampled key bioenvironmental interfaces, including irrigation water (containing the suspended solids), soils, plants, fertilizers, and atmospheric deposition, and identified the field conditions. During the period of study from Februrary to July 2020, the overall Cu inputs in Field-1 and Field-2 were 143.0 mg/m2 and 364.4 mg/m2 where the irrigation contributed (96.2% and 98.8%, respectively) the most, corresponding to a Cu accumulation rate of 0.67‒1.68 mg/kg/yr. On the other hand, harvesting eliminated the input up to 8.2% and 4.9% in Field-1 and Field-2. Interestingly, the soil Cu concentration adjacent to the irrigation ditch of Field-1 and Field-2 reached 193‒222 mg/kg and 171‒282 mg/kg, respectively, which were much higher than those samples more distant from the irrigation ditch (47‒103 mg/kg and 46‒79 mg/kg). According to the model prediction, the soil Cu concentration might exceed the regulated concentration for dietary crop farms by the year of 2043. The results indicated that the effect of Cu accumulation in soil was quite significant. While managing a paddy field, plan formation and risk assessment should be performed based on the detailed analyses of heavy metals’ inputs and outputs. Our results emphasized the importance of inter-organizational and transdisciplinary cooperation. The information of sediments in river channels and irrigation ditches should be integrated to establish a prewarning threshold, criteria and regulations. The outflow and the irrigation should be separated and monitored to avoid the pollutions from upstream. Parallel promotion of pollution elimination in upstream and downstream is of high importance. The Factory Management Act and the Spatial Planning Act should be of more attention to lower the potential risk of soil pollution. A complete model to predict the fate of Cu needs further investigation in the soil properties (e.g. soil organic matter and amorphous iron/aluminium) and the heterogeneous accumulation of Cu in soils. Also, flowmeters were essential to accurately quantify the inflow and outflow of irrigation water and heavy metals. In practice, we recommended to evaluate the feasibility of implementing the water-saving management strategies (e.g., rice ratooning, alternative wetting and drying management). When initiating remediation of ditch sediments or soils, the priorities should be placed for the green technologies which incorporate the concepts of a circular economy and green sustainability. Financially, relevant organizations should provide compensation for those who lie fallow or apply sustainable strategies to ameliorate the heavy metal accumulation.