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Since 2011, tourism to Mexico&rsquo, s Yucat&aacute, n Peninsula has been heavily impacted by large masses of sargassum seaweed washing up on the beaches, with the largest seaweed event occurring in 2019. Seaweed deters beach tourism, potentially shifting tourism inland towards other activities such as swimming in cenotes (sinkholes). Our mixed methods study combined data from surveys of visitors to the region, interviews with tourists and tour operators, thematic analysis of newspaper articles, laws and policies and analysis of water samples from a cenote to understand the environmental impact on cenotes of this shifting tourism industry. We identified intentional efforts by the tourism industry to encourage cenote tourism in response to the seaweed problem, and our survey and interview data confirmed that tourists are choosing to visit cenotes in lieu of beaches. Water samples from one tourist cenote in 2019 indicated increased pollution relative to previous years. Current regulations and management of tourist cenotes are weak, creating the potential for significant long term harm to the environment and to the water sovereignty of surrounding communities. Regulation of cenotes should be strengthened to protect these fragile karst ecosystems and to give local and indigenous residents a formal voice in the management process.

In an anaerobic digestion (AD) process, the hydrolysis phase is often limited when substrates with high concentrations of solids are used. We hypothesized that applying micro-aeration in the hydrolysis phase and the application of granular activated carbon (GAC) in the methanogenesis phase could make the AD process more efficient. A packed bed reactor (PBR) coupled with an up-flow anaerobic sludge blanket (UASB) was conducted, and its effects on methane generation were evaluated. The micro-aeration rate applied in PBR was 254 L-air/kg-Total solids (TS)-d was compared with a control reactor. Micro-aeration showed that it reduced the hydrolysis time and increased the organic matter solubilization as chemical oxygen demand (COD) increasing 200%, with a volatile fatty acids (VFAs) increment higher than 300%, compared to the control reactor (without aeration). Our findings revealed that the implementations of microaeration and GAC in the two-phase AD system could enhance methane production by reducing hydrolysis time, increasing solid waste solubilization.

The Yalahau region, located in the northeastern portion of the Yucat&aacute, n Peninsula, hosts a series of elongated depressions trending north/south in the direction of Isla Holbox, identified as the Holbox Fracture Zone. Previous studies have explored the geomorphology and various hydrologic characteristics of the Yucat&aacute, n Peninsula, however, there is a paucity of data concerning the interior region where the fractures are located. Strontium isotope ratios and major ion geochemistry data of the surface water and groundwater of this region serve as a hydrogeochemical fingerprint, aiding in constraining the hydrological boundaries, determining flow paths, and characterizing hydrogeochemical processes that impact the composition of the groundwater within the region. 87Sr/86Sr isotope ratios indicate a different signature than the surrounding bedrock Sr ratio, suggesting that the flow throughout the Yalahau region is moving through channels faster than that of much of the Yucat&aacute, n. Through major ion geochemistry and 87Sr/86Sr isotope ratios, we were able to delineate at least two flow paths within the Yalahau region and identify a point of saline intrusion at least 35 km from the coast. Gaining an understanding of the hydrogeochemistry and water flow regions is crucial in determining the impact of various activities (e.g., extensive tourism, drinking water withdrawal, wastewater discharge/injection) that occur within the Yucat&aacute, n Peninsula.