Terrestrial enhanced rock weathering (ERW) is a carbon dioxide removal technology that aims at accelerating one of the most powerful negative feedbacks on Earth's climate, the chemical weathering of silicates. To achieve this, ERW proposes to spread ground silicate rock on agricultural soils. According to many models, global application rates of 40 tonnes of ground basaltic rock per hectare and per year would be necessary to sequester a significant amount of CO₂, representing up to 24% of the current net annual increase in atmospheric CO₂. When assessing the viability of ERW as a global geo-engineering strategy, a pivotal but overlooked question to address is whether ERW may lead to toxic trace element accumulation in soils at unauthorized and potentially harmful levels. This study evaluates the legal sustainability of ERW with regard to trace element contents in soils. We compare different trace element accumulation scenarios considering a range of rock sources, application rates and national regulatory limits. The results indicate that, at the suggested annual application rate of 40 tonnes per hectare, the first regulatory limits would be exceeded after 6 and 10 years for copper and nickel, respectively. This study argues in favour of close tailoring of ERW deployment to local conditions in order to tap into its climate mitigation potential while preserving long-term soil uses.

中文翻译：

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岩石风化增强过程中土壤中有毒微量元素的潜在积累

陆地增强岩石风化 (ERW) 是一种二氧化碳去除技术，旨在加速对地球气候最强大的负面反馈之一，即硅酸盐的化学风化。为实现这一目标，ERW 建议在农业土壤上撒播磨碎的硅酸盐岩石。根据许多模型，全球每公顷每年需要使用 40 吨玄武岩碎石才能封存大量的 CO ₂，​​占目前大气中 CO _{2每年净增加量的 24%}. 在评估战争遗留爆炸物作为全球地球工程战略的可行性时，需要解决的一个关键但被忽视的问题是，战争遗留爆炸物是否会导致有毒微量元素在未经授权和潜在有害水平的土壤中积累。本研究评估了战争遗留爆炸物在土壤中微量元素含量方面的法律可持续性。我们比较了不同的微量元素积累情景，考虑了一系列岩石来源、应用率和国家监管限制。结果表明，按照每公顷 40 吨的建议年施用率，铜和镍分别在 6 年和 10 年后超过第一个监管限制。本研究主张根据当地条件密切调整战争遗留爆炸物的部署，以便在保持长期土壤用途的同时挖掘其减缓气候变化的潜力。