Wetlands Up-Scale Selenium Cycle

Affiliation(s)PIProject periodFunded by
DHS Acharya, Kumud 12/15/2010 - 06/15/2012 Southern Nevada Water Authority

Project Description

Up-Scale Selenium Cycle Data - There are several wetlands in the Las Vegas Valley, some naturally formed and some constructed in various landscape positions with a variety of hydrologic, vegetation and soil conditions. Erosion control structures constructed in recent years have created more acreage of wetlands in the Las Vegas Wash, which now offer extended habitat for aquatic life. Previous studies show that the Las Vegas Wash and its tributaries also contain elevated levels of selenium and other metalloids. With the increasing wetland area, there is a growing concern over bioaccumulation of these trace metals and pollutants. The Southern Nevada Water Authority (SNWA) has been regularly monitoring the waters in the Las Vegas Wash, its tributaries and surrounding wetlands and has established a baseline dataset for selenium concentrations. The basic task of this work is aimed at understanding the selenium distribution in the Las Vegas Wash and its tributaries by developing a process-based mathematical model of selenium fate and transport. The model will be based on a system wide mass-balance calculation which will incorporate chemical, biological and physical processes. The model will also take into account bioaccumulation by plants and volatilization potential for removing selenium from the system. The system dynamics modeling tool, Stella will be used in model development. In order to develop a model of selenium fate and transport in the Las Vegas Wash, many data sets will be needed. Numerous data sets have been collected on these sites on vegetation cover, hydrology, biology and chemistry by SNWA, Desert Research Institute, Bureau of Reclamation, U.S. Geological Survey and other agencies for many years. The study will utilize the existing data to calibrate and validate the model. Additional data will be collected at a later date if necessary. Once we have a calibrated model, we will be able to modify the various inputs (i.e., possible management actions) to achieve desirable outcomes. The project will be a continuation of ongoing studies between Desert Research Institute and SNWA to assess the ecological functions of wetlands in the Las Vegas Wash. The final objective of the project will be to provide management recommendations based on the wetlands function to remove selenium from the system by biologically or hydrologically manipulating species or removing vegetation. The collected and gathered data will be used to address the following research question for meeting the Las Vegas Wash Coordination Committee's mission; what drivers affect ecosystem services of riparian areas in extensively urbanized arid watersheds? Hypotheses tested include: water conservation measures improve water purification services by reducing the transport of selenium into Las Vegas Wash and restoration activities improve biodiversity services by mitigating for selenium contamination.