<div>
<p>Despite
its location in the rain shadow of the southern Sierra Nevada, the Panamint
Range within Death Valley National Park, CA hosts a complex aquifer system that
supports numerous springs. These springs, in turn, support unique
groundwater-dependent ecological communities. Spring emergences range in
elevation from 2434 m above sea level (within the mountain block) to 77 m below
sea level (in the adjacent basins). Waters were collected from representative
Panamint Range springs and analyzed for environmental isotopes and geochemical
tracers to address the following questions: 1) What is the primary source of
recharge for the springs? How much
recharge occurs on the Panamint Range? 2) What groundwater flowpaths and
geologic units support springflow generation? and 3) What are the residence
times of the springs? The stable isotopic composition (δ<sup>18</sup>O and δ<sup>2</sup>H) of spring
water and precipitation indicate that localized high-elevation snowmelt is the
dominant source of recharge to these perennial springs, though recharge from
rainfall is not wholly insignificant. Geochemical evolution was evaluated using
principle component analysis to compare the concentrations of all major spring
cations and anions in a multidimensional space and group them according to
dominant geochemical signatures. These resulting geochemical groups are controlled
primarily by topography. The Noonday Dolomite and other carbonate units in the
range are identified as the water-bearing units in the mountain block based on
the <sup>87</sup>Sr/<sup>86</sup>Sr of spring
waters and rock samples. These units also offer higher hydraulic conductivities
than other formations and are chemically similar. Radiocarbon- and <sup>3</sup>H derived residence
times of these spring waters range from modern to approximately 1840 years,
with the shortest residence times at higher altitudes and Hanaupah Canyon and
increasing residence times with decreasing altitude. This residence time-altitude
relationship is likewise likely topography-driven though there are significant
disparities in mountain block storage between the various canyons of the range
resulting in variable residence times between drainages. Lower Warm Springs A
and B, however, are the exceptions to this trend as they emerge at lower
altitudes (750m above sea level) and are likely driven by the transport of
groundwater to the surface along faults which increases both the temperature
and groundwater residence times of waters from these springs. Benthic
macroinvertebrates and benthic and planktonic microbes were also sampled for
each spring studied. BMI and microbial community structure in the Panamint Range
is likewise topography-controlled with more tolerant communities at lower
elevations (within more chemically evolved waters) and less tolerant species in
the unevolved waters at higher elevations.</p></div>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/7436729 |
| Date | 16 January 2019 |
| Creators | Carolyn L. Gleason (5930639) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/LIFE_IN_THE_RAIN_SHADOW_UNDERSTANDING_SOURCES_OF_RECHARGE_GROUNDWATER_FLOW_AND_THEIR_EFFECTS_ON_GROUNDWATER_DEPENDENT_ECOSYSTEMS_IN_THE_PANAMINT_RANGE_DEATH_VALLEY_CALIFORNIA_USA/7436729 |
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