Molybdenum (Mo) is a key cofactor in enzymes used for nitrogen (N) fixation and nitrate reduction, and the low availability of Mo can constrain N inputs, affecting ecosystem productivity. Natural atmospheric Mo aerosolization and deposition from sources such as desert dust, sea‐salt spray, and volcanoes can affect ecosystem function across long timescales, but anthropogenic activities such as combustion, motor vehicles, and agricultural dust have accelerated the natural Mo cycle. Here we combined a synthesis of global atmospheric concentration observations and modeling to identify and estimate anthropogenic sources of atmospheric Mo. To project the impact of atmospheric Mo on terrestrial ecosystems, we synthesized soil Mo data and estimated the global distribution of soil Mo using two approaches to calculate turnover times. We estimated global emissions of atmospheric Mo in aerosols (<10 μm in diameter) to be 23 Gg Mo yr⁻¹, with 40%–75% from anthropogenic sources. We approximated that for the top meter of soil, Mo turnover times range between 1,000 and 1,000,000 years. In some industrialized regions, anthropogenic inputs have enhanced Mo deposition 100‐fold, lowering the soil Mo turnover time considerably. Our synthesis of global observational data, modeling, and a mass balance comparison with riverine Mo exports suggest that anthropogenic activity has greatly accelerated the Mo cycle, with potential to influence N‐limited ecosystems.

中文翻译：

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人为扰动到大气钼循环

钼（Mo）是固定氮（N）和还原硝酸盐的酶中的关键辅助因子，而Mo的低可用性会限制N的输入，从而影响生态系统的生产力。沙漠尘埃，海盐喷雾和火山等来源造成的自然大气Mo雾化和沉积可以长期影响生态系统功能，但是燃烧，机动车和农业尘埃等人为活动加速了自然Mo循环。在这里，我们结合了对全球大气浓度观测和建模的综合，以识别和估计大气Mo的人为来源。为了预测大气Mo对陆地生态系统的影响，我们综合了土壤Mo数据并使用两种方法估算了土壤Mo的全球分布。计算周转时间。^-1，其中40％–75％来自人为来源。我们估算出，对于最高的土壤，钼的周转时间介于1,000年至1,000,000年之间。在一些工业化地区，人为输入增加了Mo沉积100倍，大大降低了土壤Mo周转时间。我们对全球观测数据，模型的综合以及与河流Mo出口的质量平衡比较表明，人为活动极大地加速了Mo循环，并有可能影响有限氮的生态系统。