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Stable isotopes of delta(18)O, delta(2)H, and (13)C, radiogenic isotopes of (14)C and (3)H, and ground water chemical compositions were used to distinguish ground water, recharge areas, and possible recharge processes in an arid zone, fault-bounded alluvial aquifer. Recharge mainly occurs through exposed stream channel beds as opposed to subsurface inflow along mountain fronts. This recharge distribution pattern may also occur in other fault-bounded aquifers, with important implications for conceptualization of ground water flow systems, development of ground water models, and ground water resource management. Ground water along the mountain front near the basin margins contains low delta(18)O, (14)C (percent modern...
We estimated global cyanobacterial biomass in the main reservoirs of cyanobacteria on Earth: marine and freshwater plankton, arid land soil crusts, and endoliths. Estimates were based on typical population density values as measured during our research, or as obtained from literature surveys, which were then coupled with data on global geographical area coverage. Among the marine plankton, the global biomass of Prochlorococcus reaches 120 × 10^12 grams of carbon (g C), and that of Synechoccus some 43 × 10^12 g C. This makes Prochlorococcus and Synechococcus, in that order, the most abundant cyanobacteria on Earth. Tropical marine blooms of Trichodesmium account for an additional 10 × 10^12 g C worldwide. In terrestrial...
We used variation in a portion of the mitochondrial DNA control region to examine phylogeography of Tamiasciurus hudsonicus, a boreal-adapted small mammal in the central Rocky Mountain region. AMOVA revealed that 65.66% of genetic diversity was attributable to variation within populations, 16.93% to variation among populations on different mountain ranges, and 17.41% to variation among populations within mountain ranges. Nested clade analysis revealed two major clades that likely diverged in allopatry during the Pleistocene: a southern clade from southern Colorado and a northern clade comprising northern Colorado, Wyoming, eastern Utah, and eastern Idaho. Historically restricted gene flow as a result of geographic...
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Analysis of a typical semiarid mountain system recharge (MSR) setting demonstrates that geochemical tracers help resolve the location, rate, and seasonality of recharge as well as ground water flowpaths and residence times. MSR is defined as the recharge at the mountain front that dominates many semiarid basins plus the often-overlooked recharge through the mountain block that may be a significant ground water resource; thus, geochemical measurements that integrate signals from all flowpaths are advantageous. Ground water fluxes determined from carbon-14 ((14)C) age gradients imply MSR rates between 2 x 10(6) and 9 x 10(6) m(3)/year in the Upper San Pedro Basin, Arizona, USA. This estimated range is within an order...
Freshwater mussels (unionids) are increasingly recognized as important providers of ecosystem services, yet are among the most endangered fauna in the world. Because unionids are generally sessile and require specific fish hosts for development and dispersal, they are particularly vulnerable to habitat degradation. Surprisingly, little is known about the distribution of genetic diversity in freshwater mussels and this gap has a negative impact on taxonomy, monitoring, conservation and ecological research in these species. Here, we focus on western North American Anodonta, one of only three genera known to exist in this broad landscape and which contains three highly divergent lineages. We describe phylogeographical...
    map background search result map search result map Geochemical quantification of semiarid mountain recharge. Ground water recharge and flow characterization using multiple isotopes. Geochemical quantification of semiarid mountain recharge. Ground water recharge and flow characterization using multiple isotopes.