Tracing multiple sources of salinity to the Rio Grande with multiple - - PowerPoint PPT Presentation

Tracing multiple sources of salinity to the Rio Grande with multiple isotope tracers (Uranium, Strontium, and Boron)

PIs: Lin Ma, University of Texas at El Paso Jennifer McIntosh, University of Arizona Jerome Gaillardet, IPGP, France Anna Szynkiewicz, University of Tennessee

To combine a set of environmental tracers to fingerprint and accurately quantify salt loads from natural and anthropogenic sources in the semi- arid Rio Grande watershed. Agricultural sources (U isotopes); Urban environments (B isotopes); Deep basin brine and geothermal water (Sr, B, and U). Conceptual Diagram from Hargrove et al., 2013

Complex surface-groundwater interactions and multiple salinity sources in Rio Grande: geological, agricultural, and urban impacts

Overview of Rio Grande river salinity during our project period (2014-2017)

Preliminary findings with our isotope tracer approach:

1) All three sources (geology, agriculture, and urban) were present in Rio Grande, especially during the non-irrigation and low flow seasons; 2) Sources are highly variable both spatially and temporally; 3) Monte-Carlo inverse calculations with U, Sr, and B isotope ratios can effectively quantify salinity contributions.

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

RG at WB RG at NM187 RG at NM 154 RG at NM 359 RG at 273

Percentage contributed to Rio Grande

EBR Agriculture Deep GW Shallow GW Urban

T or C Las Cruces El Paso During non-irrigation/low flow seasons

Some take-home messages:

• Geological, agricultural, and urban processes contribute

to salinity in Rio Grande;

• Shallow groundwater in the Rio Grande region is

impacted by irrigation and urban water uses;

• The multi-isotope tracer approach (U, Sr, and B) is

effective in identifying and quantifying salinity sources and possible contaminants (U, As, NO3 etc.) for river and groundwater quality in our region.