Tracing the source of Brazil nut contamination using advanced mass spectrometric methods

巴西坚果树（Bertholletia excelsa）是一种受保护的物种，对亚马逊流域的玻利维亚、秘鲁和巴西的森林经济至关重要，不能在种植园中种植。坚果是从天然森林里的野生树上收获的。大部分坚果出口到欧盟、英国和美国，为西亚马逊地区的许多农村家庭提供了唯一的固定收入，并保证了树木生长的森林的生存。作为欧盟进口管制的一部分，巴西的坚果加工厂必须证明甲基溴的含量。甲基溴是一种因对环境有害而在许多国家被禁用的农药。据了解，在种植巴西坚果的任何森林或邻近的农业景观中都没有使用甲基溴，但据报道，巴西坚果中的甲基溴含量为24至100 ppb。在25ppm或更高的浓度下，坚果不再具有“有机”的资格，尽管它们是在远离甲基溴农用化学品的天然森林中野生收获的。在百万分之50或以上，坚果就不再适合人类食用。这对商品价格产生了相当大的影响，加工和出口公司认为这是对其行业的主要威胁（比气候变化或森林砍伐更严重）。失去这一当地社区的支柱将对森林造成毁灭性的影响，因为它们的主要价值将转向大豆、牛或木材，这将导致森林砍伐。该项目将侧重于发展质谱技术和远程取样方法，以追踪甲基溴的来源。具体来说，该项目将调查不同尺度（坚果，树木，周围森林，整个玻利维亚亚马逊）的变化。我们将调查污染是来自当地环境（土壤、落叶、树木本身）还是来自农药使用造成的远距离污染，以及甲基溴水平是否与巴西坚果的营养或健康价值相关。最后，我们将确定可能预测巴西坚果市场长期威胁或缓解变化的潜在驱动因素。

Brazil nut trees (Bertholletia excelsa) are a protected species that is vital to the forest economies of Amazonian Bolivia, Peru and Brazil, and cannot be grown in plantations. Nuts are harvested from wild trees in natural forest. The majority of nuts are exported to the EU, UK and USA, providing the only regular income for many rural households in the Western Amazon region and guaranteeing the survival of the forests where trees grow. As part of import controls to the EU, Brazil nut processing plants are required to certify levels of methyl bromide, a pesticide that is banned in many countries due to its harmful environmental impacts. Methyl bromide is not known to be used in any of the forests, or adjacent agricultural landscapes where Brazil Nuts are grown, yet levels of 24 to 100 ppb have been reported in Brazil nuts. At 25 ppm or above nuts no longer qualify as 'organic', despite being wild harvested in natural forest away from agrochemical use of methyl bromide. At or above 50 ppm, nuts no longer qualify as fit for human consumption. This impacts considerably on the commodity's price and it is perceived by processing and export companies as the main threat to their industry (greater than climate change or deforestation). The loss of this mainstay on the local community would have devastating impact on the forests as their main value would switch to soya, cattle, or timber, which would entail deforestation. This project will focus on the development of mass spectrometry techniques and remote sampling methods to trace the source of methyl bromide. Specifically, the project will investigate the variation at different scales (in nuts, across the tree, within the surrounding forest, across the Bolivian Amazon). We will investigate whether the contamination is coming from the local environment (soil, leaf-litter, the trees themselves) or longer distance contamination stemming from pesticide use, and whether levels of methyl bromide correlate with any impact on the nutritional or health value of Brazil nuts. Finally, we will determine potential drivers in variation that could predict long-term threats or mitigation to the Brazil nut market.