NGqA (Center of Environmental Geology), CPMTC, Department of Geosciences, Federal University of Minas Gerais (UFMG), Belo Horizonte, 31270-901, Brazil.
Geology Center, Science and Technology Institute, Federal University of Vale do Jequitinhonha and Mucuri, Diamantina, 39803-371, Brazil.
Environ Monit Assess. 2021 Jan 26;193(2):85. doi: 10.1007/s10661-021-08876-8.
Understanding geochemical provenances and their respective geochemical background values is crucial to sustain a proper comprehension of a tropical ecosystem and provides a compatible evaluation for further environmental policy and monitoring. In this research, the concentrations of Mg, Al, Ca, Cr, Fe, Co, Cu, Cd, Ti, Mn, Ni, Zn, Ba, Pb, and organic matter were measured in 78 samples of bottom sediments in order to evaluate the influence of geogenic and anthropogenic chemical sources in the Três Marias reservoir. Data exploration analysis, multivariate techniques using compositional data, multielemental mapping, geochemical background based on land-use management and geological domains, and enrichment factors were applied to understand the environmental dynamics. Geochemical signatures highlight three pronounced geological structures that control the sediment supply in the Três Marias reservoir: ultramafic rocks from the Mata da Corda Formation, carbonates from the Três Marias Formation, and pedogenic cover formed by tropical Latossoils. The median values of Cu, Ti, and Pb are 28.83 mg/kg, 20.36 mg/kg, and 24.92 mg/kg, respectively, all of which exceed the average upper continental crust concentrations. Pb and Cu ratios reach the threshold effect level, whereas Cr reaches the probable effect level proposed in the CONAMA 454/2012 (Brazilian environmental guidelines). This research conjugates multielemental mapping, background evaluation, and enrichment factors to elucidate the geochemistry dynamics of the Três Marias reservoir in the sense of understanding the behavior of the bottom sediments and to define geochemical reference values for the upper São Francisco basin.
了解地球化学成因及其相应的地球化学背景值对于正确理解热带生态系统至关重要，并且为进一步的环境政策和监测提供了兼容的评估。在这项研究中，测量了 78 个底泥样品中的 Mg、Al、Ca、Cr、Fe、Co、Cu、Cd、Ti、Mn、Ni、Zn、Ba、Pb 和有机质的浓度，以评估地球化学和人为化学源对特雷斯马里亚斯水库的影响。应用数据探索分析、多元技术（包括基于成分数据的多元技术）、多元素图、基于土地利用管理和地质域的地球化学背景以及富集因子，以了解环境动态。地球化学特征突出了控制特雷斯马里亚斯水库沉积物供应的三个显著地质结构：马塔达科达地层的超镁铁质岩石、特雷斯马里亚斯地层的碳酸盐岩和由热带拉托索土壤形成的成土覆盖层。Cu、Ti 和 Pb 的中值分别为 28.83mg/kg、20.36mg/kg 和 24.92mg/kg，均超过了平均大陆地壳浓度。Pb 和 Cu 的比值达到了阈值效应水平，而 Cr 则达到了 CONAMA 454/2012（巴西环境指南）中提出的可能效应水平。本研究结合了多元素图、背景评估和富集因子，以阐明特雷斯马里亚斯水库的地球化学动态，从而了解底泥的行为，并为上圣弗朗西斯科流域定义地球化学参考值。
