HydroMix

Knowledge graph centered on HydroMix with 29 nodes and 93 connections. Top connected: Gothic, Crested Butte, East River, Gunnison, Pinus ponderosa.

Method synopsis

Combined use of major ion chemistry and Sr isotope signatures to identify distinct groundwater end members and quantify their contributions to stream flow using PCA-based end member mixing analysis.

Synthesized from method descriptions across 2 papers using this protocol.

Procedure from a recent peer-reviewed implementation

Steps below were extracted from the most recent peer-reviewed implementation of this protocol in the corpus — Hidden features: How subsurface and landscape heterogeneity govern hydrologic connectivity and stream chemistry in a montane watershed (2025), Hydrological Processes. Implementations in other papers (listed below) may differ.

1. Collect groundwater spring samples as end members
   Samples from groundwater springs and near-stream piezometer were used to represent end member inputs to stream water. Only one sample was collected from each end member. One groundwater spring was located on a fractured hillslope, and the other groundwater spring was located within a dense spring network. The topographic position and geochemistry of these samples suggest that the fractured hillslope spring represents shallow, subsurface flow and the spring network represents deeper, older subsurface flow.
   Quantities: One sample collected from each of two groundwater springs representing quick flow and slow flow end membersDuration: Single collection during summer 2021Conditions: Representative sampling from springs with different hydrologic characteristics
   Equipment: sampling equipment for spring water collection
2. Conduct Sr isotope analysis
   For Sr isotopic analysis, the filtered and acidified cation samples were used. Sr concentrations were evaluated to provide insight into water source contribution to the stream. 87Sr/86Sr ratios were measured and sample 87Sr/86Sr ratios were normalised to a NIST987 value of 0.710245. Sr was separated from other elements using Sr resin (Eichrom Technologies Inc.) on miniature Teflon columns. The end members and stream samples were analysed for Sr isotopes and concentrations.
   Quantities: Sr isotope analysis conducted on subset of samples for end member identificationDuration: Laboratory analysis following initial chemical analysisConditions: Mass spectrometry laboratory conditions

Typical Equipment

• Sr resin (Eichrom Technologies Inc.)
• miniature Teflon columns
• mass spectrometry equipment

Output Measurements

• end member contributions
• 87Sr/86Sr ratios
• hydrologic connectivity patterns

Papers Using This Protocol (2)

Species Studied With This Protocol

Places Where Used