Dryland soils provide different societal and environmental services, such as food supply and biodiversity support. In Europe, most of the dryland areas are devoted to agriculture. In the next decades, both European and worldwide drylands are expected to suffer with increased intensity due to the expected climate change-derived rise in aridity. Many studies have focussed on aridity-induced changes in major nutrients in drylands, but little is known of the impact of environmental and biogeochemical factors on micronutrients with critical roles in life, and as inorganic contaminants with ecotoxicological implications. We analysed and explored drivers of total and available concentrations of micronutrients (Co, Cu, Fe, Mo, Mn, Ni and Zn) and contaminants (As, Cd and Pb) in 148 soil samples collected from European drylands covering a wide range of aridity and of other geochemical parameters. The availability of micronutrients increased with their total content, decreased with pH and was enhanced by organic C content. Aridity decreased the availability of Fe, a key element in human diet. Our findings also highlight the scarcity of this micronutrient in European drylands, as well as of some other important micronutrients like Zn and Mo in agricultural soils. Total content was the main driver of the availability of Cd and Pb, and organic matter exerted synergistic effects on contaminant release. Our data show the need for precise management practices to be incentivised by agricultural and environmental policies in order to ensure micronutrient supply and avoid contamination, thus maintaining adequate levels of agricultural productivity and simultaneously preserving dryland ecosystems.

中文翻译：

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欧洲旱地土壤微量营养素和污染物可用性的干旱和地球化学驱动因素

旱地土壤提供不同的社会和环境服务，例如食物供应和生物多样性支持。在欧洲，大部分旱地地区都用于农业。在接下来的几十年中，由于预期的气候变化导致的干旱加剧，预计欧洲和世界各地的旱地都将遭受更大的损失。许多研究都集中在干旱引起的旱地主要营养物质的变化，但对环境和生物地球化学因素对在生命中起关键作用的微量营养素以及作为具有生态毒理学意义的无机污染物的影响知之甚少。我们分析和探索了微量营养素（Co、Cu、Fe、Mo、Mn、Ni 和 Zn）和污染物（As、从欧洲旱地采集的 148 个土壤样品中的 Cd 和 Pb)，涵盖范围广泛的干旱和其他地球化学参数。微量营养素的有效性随着其总含量的增加而增加，随着 pH 值的降低而随着有机碳含量的增加而增加。干旱降低了铁的可用性，铁是人类饮食中的关键元素。我们的研究结果还强调了这种微量营养素在欧洲旱地的稀缺性，以及农业土壤中其他一些重要的微量营养素（如锌和钼）的稀缺性。总含量是 Cd 和 Pb 有效性的主要驱动因素，有机物对污染物释放具有协同作用。我们的数据表明，需要通过农业和环境政策来激励精确的管理实践，以确保微量营养素供应并避免污染，