基于生命周期评价的杨梅鲜果碳足迹研究

Carbon footprint assessment of Myrica Rubra fresh fruit based on LCA

  • 摘要: 碳足迹是衡量生产某一产品在其生命周期直接或间接排放的CO2当量。在推动绿色可持续发展的背景下, 产品碳足迹是评估产品环境影响的重要指标, 有助于企业和个人制定相应的减排措施和绿色发展战略。中国是杨梅原产地, 其栽培和利用历史至少可以追溯到2000多年前, 而今在多个地区依旧存在广泛种植和生产, 并成为当地的农业特色和主导产业。本文以生命周期评价方法为基础, 采用ISO14067和PAS 2050中规定的碳足迹核算方法, 对怀化某杨梅基地鲜果产品碳足迹进行了系统研究。杨梅鲜果没有指定的产品碳足迹-产品种类规则(CFP-PCR), 本文结合实际, 将功能单位定义为生产1 kg杨梅鲜果, 系统边界为从摇篮到农场大门类型。活动水平数据通过调研获得, 涵盖原料获取和运输、杨梅种植(除草、整形、修剪、施肥和采摘)、包装仓储等生命过程; 排放因子来源于联合国政府间气候变化专门委员会(IPCC)数据库、中国生命周期基础数据库(CLCD)和中国产品全生命周期温室气体排放系数库(CPCD 2.0)以及公开发表的文献。经核算, 该基地生产1 kg杨梅鲜果的净碳足迹为0.1853 kg(CO2-eq)·kg−1, 其中原料获取、种植过程和包装存储环节对整体碳足迹的贡献率分别为63.00%、36.31%和0.69%。对比不同碳排放来源看, 肥料上游生产及施肥后的直接排放是杨梅鲜果碳足迹最主要的排放源, 累计贡献率可达91.00%, 其中复合肥累计占比59.91%, 有机肥累计占比31.09%。从单个碳排放源看, 复合肥上游生产贡献率最大(42.92%), 其次为有机肥的上游生产贡献率(18.56%), 为此复合肥的减量增效对杨梅鲜果碳减排意义重大。本文采用ISO 14067中规定的方法进行不确定性分析(评估数据和计算过程的可靠性)和敏感性分析(评估不同系统边界设定对最终结果的影响)。结果显示, 本研究碳足迹核算结果的不确定性较小(贡献率变幅为±9%区间内), 当两种肥料的活动数据在±20%间变动时, 复合肥敏感性最大(贡献率变幅为−8.28%~7.32%), 其次为有机肥(贡献率变幅为−5.39%~5.04%)。为进一步降低杨梅鲜果产品碳足迹和提升竞争力, 从原料、生产、运输和包装等方面给出了碳减排措施和改进建议, 以期能够为本地杨梅产业科学控制温室气体排放和发展低碳农业提供参考依据。

     

    Abstract: The carbon footprint is a measure of the CO2 equivalent emissions directly or indirectly emitted by the production of a product over its life cycle. In the context of promoting green and sustainable development, product carbon footprint is an important indicator for assessing the environmental impact of products, which helps enterprises and individuals to formulate corresponding emission reduction measures and green development strategies. China is the origin of Myrica rubra, with a history of cultivation and utilisation dating back at least 2,000 years, which have been widely cultivated and produced in a number of regions, and have become a local agricultural speciality and leading industry.This study examined the carbon footprint of fresh Myrica rubra fruit from Huaihua, China, using the life cycle assessment method (LCA). The accounting procedure made use of the PAS 2050 and ISO 14067 carbon footprint accounting techniques. Since Myrica rubra fruit lacks designated carbon footprint of a product-product category rule (CFP-PCR), this study defines the functional unit as producing 1 kg of fresh Myrica rubra fruit based on real-world scenarios. The type from cradle to gate determines the system boundaries. The life processes of raw material acquisition and transportation, waxberry cultivation (weeding, shaping, pruning, fertilization and picking), packaging and warehousing, etc., were covered by the activity level research data that was gathered through on-site inquiry. The emission factors are obtained from the IPCC database, China Life Cycle Basic Database (CLCD), China Product Life Cycle Greenhouse Gas Emission Coefficient Database (CPCD 2.0), and publically released authoritative literature. The product carbon footprint of producing 1 kg of fresh Myrica rubra fruits in the plantation base was calculated to be 0.1853 kg(CO2-eq)kg−1, of which the contribution of raw material acquisition, planting process, packaging and storage to the overall carbon footprint was 63.00%, 36.31% and 0.69%, respectively. Comparing the different carbon emission sources, the upstream fertiliser production and the direct emission after fertiliser application are the most important carbon emission sources for the carbon footprint of fresh Myrica rubra fruits, and the cumulative contribution can reach 91.00%, of which the compound fertilizer is 59.91% and the organic fertilizer is 31.09%. Analysing the individual carbon emission sources, it was found that the upstream compound fertilizer production contributed the most to the carbon footprint of the product (42.92%), followed by organic fertilizer production (18.56%), so the reduction and efficiency of compound fertilizer is significant to the carbon emission reduction of Myrica rubra fresh fruits, and is the key link of carbon emission reduction. Uncertainty analysis (assessing the reliability of the data and calculation process) and sensitivity analysis (assessing the impact of different system boundary settings on the final results) were conducted using the methods specified in ISO 14067, The results showed that the uncertainty of the carbon footprint accounting results in this study was small (the variation of the contribution rate was within the range of ±9%). When the activity data of the two fertilizers varied within the range of ±20%, the sensitivity of compound fertilizer was the highest (the variation of the contribution rate was within the range of −8.28% to 7.32%). The second was organic fertilizer (the contribution rate varied within the range of −5.39%~5.04%). Scientific carbon reduction strategies and recommendations have been put forth from the perspectives of raw materials, production, transportation, packaging, etc. in an effort to further lower the carbon emissions of Myrica rubra fresh fruit products and increase their competitiveness in the market. In short, the aim is to further help achieve local carbon peak and carbon neutrality goals by serving as a reference for the scientific management of greenhouse gas emissions in the waxberry sector and the development of low-carbon agriculture.

     

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