Cadmium behavior in a karst environment hydrological cycle

• Published in: Environmental science and pollution research international Vol. 27; no. 9; pp. 8965 - 8979
• Main Authors: Lucon, Thiago Nogueira, Costa, Adivane Terezinha, Galvão, Paulo, Leite, Mariangela Garcia Praça
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.03.2020; Springer Nature B.V
• Subjects: Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Brazil; Burning; Cadmium; Cadmium - analysis; Contamination; Depuration; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental Monitoring; Environmental science; Fluid dynamics; Fluid flow; Groundwater; Hydrodynamics; Hydrologic cycle; Hydrology; Karst; Rain; Rain water; Rainfall; Rainy season; Reproduction (copying); Review Article; Surface water; Surface-groundwater relations; Waste Water Technology; Water Management; Water Pollutants, Chemical - analysis; Water Pollution Control; Watersheds; World population; Brazil; Natural background level; São Miguel watershed; Cadmium contamination
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-020-07894-2

Karst regions are important water providers, supplying approximately 25% of the world population. These areas present higher vulnerability to contamination due to hydrodynamics, which hampers the natural depuration of these waters until reaching the underground environment. High concentrations of cadmium (Cd) are observed in the São Miguel watershed, state of Minas Gerais, Brazil. This toxic element is generally and predominantly released into the atmosphere by burning materials that have Cd in their composition, potentially contaminating surface and groundwater. Therefore, the objective of the study is to map Cd concentrations in the hydrological cycle of the São Miguel karst watershed and, through natural background level values (NBL 90%) of rainwater, surface water and groundwater, to understand the seasonal behavior of this element, and to identify the most vulnerable areas to contamination. To achieve this goal, rainwater, surface, and groundwater seasonal monitoring were conducted in 87 sampling stations. A total of 335 samples were collected, distributed over a watershed area of 520 km 2 . Concentrations of cadmium above 1 μg/L were found in 21.49% of samples during the rainy season. The origin and distribution of Cd were related to rainfall. For rainwater samples, 90% presented Cd concentration of 3.06 μg/L. When these waters precipitate, they contaminate surface waters (NBL 90% = 1.50 μg/L) and groundwater (NBL 90% = 2.81 μg/L). This study presented a hydrochemical cycle map and proposed NBL values of Cd for surface water and groundwater, helping to understand how the environment is contaminated by this element.