Pub Date : 2018-07-04DOI: 10.21715/GB2358-2812.2018321088
N. Silva, A. B. de-Campos
Cultivation of flooded rice has developed in wetlands of the Cerrado Biome as a result of the expansion of the Brazilian agricultural frontier. Changes in soil moisture content due to agricultural practices associated with flood irrigation may induce geochemical transformations in the soil. The present study aimed at investigating the effect of flood irrigation on inorganic carbon cycling through the determination of dissolved inorganic carbon (DIC) concentrations. Incubation experiments under anoxic and reducing conditions were carried out in laboratory with samples of horizons A, AB, Bf1 and Bf2 of Plinthosols profiles from areas under 20 and 30 year of flood irrigation and natural area of the Irrigation Project Luiz Alves do Araguaia, GO, Brazil. Soil samples under flooding were incubated for 1, 7, 15, 30, 60 and 120 days to simulate the effect of prolonged flooding and after incubation the liquid fraction was analyzed for DIC. Higher concentrations of DIC were found in the A horizon (up to 37.2 mg/L) from soil profiles under cultivation, which may be associated with liming or desorption processes of carbon species. DIC correlated with soil electrical conductivity and Eh. It is concluded that solubilization of inorganic carbon is favored by flood irrigation, especially in Plinthosols that have received liming, as well as by the reducing state of the soil and higher concentrations of ions in solution.
由于巴西农业边界的扩大，塞拉多生物梅湿地发展了淹水水稻的种植。与洪水灌溉相关的农业实践导致的土壤含水量变化可能会导致土壤的地球化学变化。本研究旨在通过测定溶解无机碳（DIC）浓度来研究洪水灌溉对无机碳循环的影响。在缺氧和还原条件下，在实验室中对巴西GO Luiz Alves do Araguaia灌溉项目的20年和30年洪水灌溉区和自然区的Plithosols剖面的A、AB、Bf1和Bf2层样品进行了培养实验。将淹水条件下的土壤样品孵育1、7、15、30、60和120天，以模拟长期淹水的影响，并在孵育后分析液体部分的DIC。在栽培土壤剖面的A层中发现了更高浓度的DIC（高达37.2 mg/L），这可能与碳物种的石灰化或解吸过程有关。DIC与土壤电导率和Eh相关。得出的结论是，漫灌有利于无机碳的溶解，特别是在接受石灰处理的Plithosol中，以及土壤的还原状态和溶液中较高浓度的离子。
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Pub Date : 2018-07-04DOI: 10.21715/gb2358-2812.2018321040
Heloiza Márcia Fernandes-Horn, A. Horn, R. A. Sampaio, M. Rodrigues, L. Duarte, E. Bilal, Hernando Baggio Filho, I. Torres
The target area of this work is a heavy metal anomaly in the surroundings of a gold mine and a lead mining complex. This work investigated the distribution of selected heavy elements in soil samples and Si-Phytoliths from plants. The aim was to verify if metal contents are indicative for metal anomalies in the soil. Plants and soil samples were collected in profiles over granitic-gneissic rocks, which form the basement, in tectonized contact with the overlaying sedimentary units belonging to the Riacho dos Machados Group, part of the Espinhaco Super Group. The whole rock substrate is covered by lateritic to arenitic soils with different exposure depths. Metal-rich fluid invaded these units, forming metal anomalies culming in Zn-Pb-Au deposits, like that of Salobre-Porteirinha. After appropriate preparation, the samples were, analyzed by ICP-OES (Si-Phytoliths) and FRX (soil). Anomalies in the investigated profile are indicated by high metal contents in the Si-Phytoliths of the selected species. Using different species the metal concentration in different depths can be determined in a simple and easy way. The Si-Phytolith concentrations seem to reproduce better the rock metal anomalies than the soil samples.
本工作的靶区为金矿和铅矿复合体周围的重金属异常区。本文研究了土壤样品和植物硅基植物岩中部分重元素的分布。目的是验证金属含量是否表明土壤中的金属异常。植物和土壤样本是在花岗岩-片麻岩剖面上收集的，这些花岗岩-片麻岩构成了基底，与属于Riacho dos Machados群的上覆沉积单元(属于espinhaaco超级群的一部分)有构造接触。整个岩石基底覆盖着不同暴露深度的红土-砂质土。富金属流体侵入这些单元，在Salobre-Porteirinha等锌铅金矿床中形成金属异常。样品经适当制备后，采用ICP-OES(硅-植物岩)和FRX(土壤)分析。所研究剖面的异常表现为所选物种硅植物岩中金属含量高。用不同的种类测定不同深度的金属浓度，方法简单易行。硅-植物岩浓度似乎比土壤样品更能再现岩石金属异常。
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