Hydrogeochemical Influence on the Nitrogen and Phosphorus Concentration and Stocks in Herbaceous Karst Wetlands

Nitrogen and phosphorus concentrations were quantified in interstitial water, soil, and the roots of Cladium jamaicense Crantz from four herbaceous wetlands in southeast Mexico, locally known as sabanas, which are established in the karstic valley of the Holbox fracture system (northern Quintana Roo). We used the physicochemical and hydrogeochemical properties of the water to identify the existence of any relationships between nutrient (nitrogen and phosphorus) concentration and stock, and the hydrogeochemistry of each wetland. The wetlands have different classifications: H1 and H2 are palustrine, H3 is lacustrine, and H4 is estuarine. We found greater total phosphorus mass (mg kg⁻¹) in the roots compared to the soil, which was particularly large in the wetland located at the south end of the western fracture. In general, phosphorus and nitrogen had a trend in the interstitial water and soil in which concentration and mass were higher H1 > H3 > H4, different from H2; these trends were not observed in the soil or roots. The N and P concentrations in the soil and roots were different among the wetlands, with the lowest measured at the site with brackish influence. The results presented in this research allow us to compare the nitrogen and phosphorus that can be stored in tropical karst wetlands and relate them to hydrogeochemistry.