Search

Copyright of Ecosistemas y Recursos Agropecuarios is the property of Universidad Juarez Autonoma de Tabasco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Karst wetlands provide important ecosystem services such as maintenance of hydrological balance, flood regulation, drinking water supply and nutrients cycling. It is important to conserve and maintain karst wetlands due to its interaction with groundwater systems and its socioeconomic relevance. The objective of this research was to generate base-line knowledge of the microtopography, hydroperiod and biogeochemical characteristics of poorly known tropical karst marshes by testing two hypotheses, the phreatotrophic nature of tropical karst marshes, and the alteration of its biogeochemistry by a highway dividing the marsh. The study site is located in the north of the state of Quintana Roo (Mexico), in pseudo-paludal depressions associated to fractures. The water level varied from few centimeters below the ground to more than 100 cm. We demonstrate that the wetland is groundwater-fed with differences among groundwater, interstitial and surface water in almost all parameters measured. The water is calcium bicarbonate type; the main processes occurring are recharge, evaporation and rock dissolution. Our results suggests denitrification, low phosphates attributed to Ca- and Fe/Al-bound P, elevated alkalinity and sulfate reduction due to anaerobic conditions in water and soil. The soil reflect its sedimentary origin, the bulk density is low with very high water retention capacity. We do not have enough evidence of the highway modifying the biogeochemistry or hydrology of the marsh. These karst wetlands provide important provisioning and supporting ecosystem services that should be studied, acknowledged and maintained. [ABSTRACT FROM AUTHOR]

Sinkholes are common karst forms were we can access the aquifer. This study describes an 85 m deep sinkhole in north Quintana Roo (Mexico), located at 45 km from the coast, allowing us to explore an open section of the aquifer. The profile of the water column was realized to evaluate the physical chemistry, hydrochemistry and water isotopes (δ2H, δ 18O and 3H) in order to distinguish the stratification. It was identified water-rock interaction (limestone) in the upper section (0–40 m), typical from karst groundwater; a mixing zone approximately 10 m thick, and saline intrusion in the deep section (50–80 m). Salinization of the freshwater was observed, likely due to diffusion of sodium and chloride from the deep water. The hydrochemistry suggests seawater intrusion contributing as much a 60% of the water in the deep section. With the stable isotopes, meteoric water, groundwater and seawater mixing was attested. The tritium measurements suggest that the aquifer has short residence time and fast recharge. Few deep sinkholes in Mexico have been studied, the information obtained in Yumkin contributes to the knowledge and understanding of the Yucatan aquifer system. [Display omitted] • Meteoric water, groundwater and seawater mixing occurs in an 85 m deep sinkhole. • Seawater intrusion is about 60% at 80 m. • Tritium suggest fast groundwater recharge and short residence time. • Data contributes to a better understanding and long-term aquifer management. [ABSTRACT FROM AUTHOR]