MULTIDISCIPLINARY WORK TO DETERMINE HYDROLOGY OF ARID LAND SPRINGS AND HOW SPRING WATERS INFLUENCE WATER QUALITY AND ECOSYSTEM HEALTH FOR DESERT ENVIRONMENTS
In the desert southwestern United States, water resources are stressed due to anthropogenic use, drought and climate change. Arid land spring sites are considered hotspots for biodiversity, providing refugia to aquatic habitats during dry seasons. To quantify the importance of desert land springs, this research applied an interdisciplinary approach to assess 78 springs of Cibola National Forest, New Mexico. Of specific importance are several springs that provide habitats for the endangered Zuni Bluehead Sucker (ZBS), Zuni Mountains, New Mexico. Inputs to the three remaining ZBS habitats include spring waters and shallow alluvium waters from stream channels upstream from spring discharge. This research used hydrogeochemical methods to determine flow paths, mixing scenarios, residence time and recharge mechanism for ground, surface and spring waters for the ZBS habitats. Continuous monitoring of physico-chemical parameters at the three ZBS habitats lead me to propose a water quality stability classification (WQSC) that differs upstream and downstream from spring inputs: 1) high WQSC (downstream from perennial spring), 2) medium WQSC (perennial waters upstream from spring) and 3) low WQSC (stream areas that dry). Sampling of biological communities showed that biodiversity varies with and may be influenced by the WQSC. Hydrogeochemical analysis indicate that springs are from confined regional and local aquifers. Isotopologues (δ18O, δD, 3H) indicate that spring waters discharge from confined aquifers and are recharged primarily through snowmelt with a residence time greater than 70 years. In contrast, waters in the shallow alluvium are recharged from both snow and rain events. Geochemical mixing models explain seasonal inputs to ZBS habitats, where spring waters provide up to 99% of water during dry seasons. Continuous monitoring indicates that springs provide input of geochemically stable waters that maintain appropriate physico-chemical parameters (dissolved oxygen concentrations and specific conductance). In contrast medium WQSC areas become stagnant, anoxic and concentrated in ions. Areas with low WQSC dry completely. Biologic communities at different WQSC are significantly different from each other. Overall results show that springs of the Zuni Mountains are drying and those remaining are essential to water quality and biodiversity.
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