Department of Soil Science, Federal University of Lavras, Lavras, MG CEP 37200-900, Brazil.
Embrapa Rondônia, Porto Velho, RO CEP 76815-800, Brazil.
Sci Total Environ. 2022 Jul 1;828:154426. doi: 10.1016/j.scitotenv.2022.154426. Epub 2022 Mar 9.
The Amazon rainforest is a heterogeneous ecosystem and its soils exhibit geographically variable concentrations of trace elements. In this region, anthropic activities - e.g., agriculture and mining - are numerous and varied, and even natural areas are at risk of contamination by trace elements, either of geogenic or anthropogenic origin. A reliable dataset of benchmark values for selenium (Se), barium (Ba), and iodine (I) concentrations in soils is needed for use as a reference in research and public policies in the region. In this study, 9 selected sites in the Brazilian Amazon rainforest within areas represented by Oxisols and Ultisols were assessed for relevant soil physicochemical characteristics, along with the concentrations of total Se (Se), total Ba (Ba), and sequentially-extracted soluble Se (Se) and adsorbed Se (Se) in 3 different soil layers (0-20, 20-40, and 40-60 cm). In addition, organically bound-Se (Se) and total I (I) concentrations in the surface layer (0-20 cm) were measured. Soil Se concentrations (Se) were considered safe and are likely a result of contributions of sedimentary deposits from the Andes. Available Se (Se + Se) accounted for 4.5% of Se, on average, while Se in the topsoil accounted for more than 50% of Se. Barium in the western Amazon (state of Acre) and central Amazon (Anori, state of Amazonas) exceeded national prevention levels (PVs). Furthermore, the average I in the studied topsoils (5.4 mg kg) surpassed the worldwide mean. Notwithstanding, the close relationship found between the total content of the elements (Se, Ba, and I) and soil texture (clay, silt, and sand) suggests their geogenic source. Finally, our data regarding Se, Ba, and I can be used to derive regional quality reference values for Amazon soils and also for updating prevention (PV) and investigation (IV) values established for selected elements by the Brazilian legislation.
亚马逊雨林是一个多相生态系统，其土壤中微量元素的浓度具有地域差异。在这一地区，农业和矿业等人为活动多种多样，即使是自然区域也有受到微量元素污染的风险，这些元素可能源自地球化学成因，也可能源自人为成因。本研究中，在巴西亚马逊雨林选取了 9 个具有典型代表性的样本点，其土壤类型为氧化土和老成土，分析了这些样本点的土壤理化性质，以及总硒（Se）、总钡（Ba）和不同土壤层（0-20、20-40 和 40-60cm）中可提取的硒（Se）和吸附态硒（Se）的浓度。此外，还测定了表层（0-20cm）土壤中的有机结合态硒（Se）和总碘（I）浓度。土壤硒浓度（Se）被认为是安全的，可能是安第斯沉积物的贡献。有效态硒（Se+Se）占总硒（Se）的 4.5%，而上层土壤中的硒（Se）占总硒（Se）的 50%以上。在西部亚马逊（阿克里州）和中部亚马逊（安诺里州，亚马逊州），钡的含量超过了国家预防水平（PVs）。此外，在所研究的表层土壤中碘的平均含量（5.4mg/kg）超过了全球平均值。尽管如此，研究中发现这些元素（硒、钡和碘）的总含量与土壤质地（粘土、粉砂和砂）之间存在密切关系，这表明它们具有地球化学成因。最后，我们关于硒、钡和碘的数据可用于推导出亚马逊土壤的区域质量参考值，并可用于更新巴西法规为选定元素规定的预防（PV）和调查（IV）值。
