Integrating impacts from marine plastics in Life Cycle Assessment

海洋垃圾，即塑料，是一个日益严重的环境问题，环境决策者开始采取行动/实施旨在减少塑料使用和废物管理不善的法规。继欧盟委员会之后，加拿大政府已经宣布最早将于2021年禁止使用有害的一次性塑料。加拿大的声明还明确指出，所采取的措施将“以科学证据为基础”，这意味着需要有证据表明这些禁令和新的解决方案从环境的角度来看是一种改进，以支持这些决定。生命周期评估（LCA）是一种支持环境决策的工具，专门用于识别产品替代品之间的潜在权衡，例如一次性塑料杯与纸杯。然而，虽然LCA被广泛用于支持决策，但目前还没有方法来评估LCA中海洋垃圾（包括塑料）的影响。这可能会限制在评估诸如塑料禁令或创新解决方案等决策时，将LCA作为强调影响类别之间潜在权衡的工具的应用。本研究旨在发展不同的影响途径机制，提出表征模型和因子，将塑料对海洋环境的影响纳入生命周期评估框架和方法。本项目的不同研究轴侧重于释放到水生和海洋环境中的微塑料及其完整的影响途径建模：1)从塑料进入不同环境隔间和子隔间的命运，2)物种对颗粒的暴露，以及3)这种塑料暴露对LCA生态系统质量损害类别的影响。此外，还量化了参与这一影响途径的大塑性凋落物向微塑性的降解。因此，该计划将允许在LCA中考虑在管理良好的废物系统之外发生的塑料产品寿命终止的潜在影响。这些信息将告知决策者在考虑不同的替代品（例如产品或包装）时，比较每种替代品的潜在影响和益处，而不会被感知到的问题或不包括这些影响的结果所误导。通过将这些潜在的损害纳入LCA模型，影响置换——比如选择一种因为避免使用一次性塑料而会增加全球变暖潜势的替代方案——可以从LCA的结果中得到信息，而且决策确实“基于科学证据”。

Marine litter, namely plastic, is a growing environmental problem and environmental decision makers are beginning to take actions/implement regulations that aim to reduce plastic use and waste mismanagement. The government of Canada has already announced that it will ban harmful single-use plastics as early as 2021, following the lead from The European Commission. The Canadian statement also specified that the measures taken would be "grounded in scientific evidence", meaning that evidence that such bans and new solutions are an improvement from an environmental perspective are needed to support these decisions. Life Cycle Assessment (LCA) is a tool for supporting environmental decision making that is specifically designed to allow for the identification of potential trade-offs between product alternatives e.g. a single use plastic versus paper cup. However, whilst LCA is widely used in support of decision making, there is currently no methodology for impact assessment of marine litter, including plastic, in LCA. This potentially limits the application of LCA as a tool for highlighting potential trade-offs between impact categories when assessing decisions such as plastic bans or innovative solutions. This research aims at developing the different impact pathway mechanisms in order to propose characterization models and factors, allowing the integration of impacts generated by plastic in the marine environment within the Life Cycle Assessment framework and methods. The different research axis included in this program focus on microplastics released into the aquatic and marine environment, and their complete impact pathway modelling: 1) from the fate of the plastic into the different environmental compartment and sub-compartments, 2) the exposure of the species to the particles, and 3) the effect this plastic exposure can have on the ecosystem quality damage category in LCA. In addition, the degradation of macroplastic litter into microplastic contributing to this impact pathway is also quantified. This program will therefore allow the consideration in an LCA of the potential impacts of the end-of-life of plastic-based products when occurring outside of the well-managed waste systems. This information will inform the decision makers looking at different alternatives (e.g. for a product or a packaging) to compare the potential impacts and benefits of each alternatives, without being misled, either by a perceived problem, nor by a result which does not include such impacts. By including these potential damages into LCA models, impact displacements - such as choosing an alternative that would increase global warming potential because it avoids single use plastic - can be informed by the LCA results and decisions indeed be "grounded in scientific evidence".