Can anthropization govern the water and carbon dynamics? A case study of peatlands in Serra do Espinhaço Meridional, Brazil

Abstract

Peatlands are ecosystems formed mostly by organic matter and water and constitute a particular type of free aquifer. They perform important hydrological functions by storing excess water during rainfall events, contributing to the baseflow of its rivers throughout the year. Its degradation affects the water table dynamics and influences the decomposition of organic matter content and the release of carbon into its waters. The water retention capacity may also be compromised and thus reduce the volume of water available downstream, especially in the dry season. This study aimed to evaluate the effects of anthropic interference on variations in groundwater level, water storage, and carbon flow in two tropical mountain peatlands, located at the head of the Araçuaí River, in Serra do Espinhaço Meridional, Minas Gerais State, Brazil. Level meters were installed in groundwater wells distributed on peatland zones located in a protected area (Natural Park) (Protected—TP) and outside the conservation unit (Anthropized—TA). Data were analyzed considering the daily rainfall recorded by an automatic weather station installed in the study area. From the data on precipitation and water table level variation, the specific yield (Sy) in the two peatlands was calculated. The observed flows and the mean monthly Sy on each groundwater well were correlated and their significance was verified using the t-test (p < 0.05). The relationship between the observed flow and the mean monthly values of Sy obtained for the groundwater wells was verified through multiple regression. The Sy correlated significantly with the flow in both peatlands (p < 0.05). Multiple linear regression showed a coefficient of determination (R²) of 0.92 in both peatlands, indicating a direct relationship between Sy and observed flow. The TP presented a 43% smaller variation in the water table, a 7% higher Sy, and a specific flow rate of 13% higher related to the TA. The peatland located in the protected area retains more water, with less variation in flow throughout the year, and releases less carbon in the water compared to the anthropized peatland. The results demonstrate that anthropization is causing peatland degradation, reducing its water-holding capacity and accelerating its carbon losses. In the medium term, these effects may lead to a drastic reduction in flow in the upper course of the Araçuaí River.