The WRRI homepage (http://wrri.nmsu.edu) contains a list of all published completion reports along with each report's abstract. In the near future, the Institute hopes to provide, via its homepage, the full text of each new report.
Four completion reports were published recently. For copies of the reports, contact the WRRI at 646-1813.
The researchers found elevated concentrations of both organic and inorganic forms of mercury in the upstream portion of Caballo Reservoir, and this finding lead to a continued investigation of Elephant Butte Reservoir and Rio Grande water coming into Caballo Reservoir. High levels of biologically available methylmercury in the upper section of Caballo Reservoir are attributed to the discharge of anoxic Elephant Butte waters to the Rio Grande.
The study determined a potential source of mercury in the Rio Grande basin to be atmospheric deposition. Further study is needed to describe Hg concentrations in runoff from the Black Range watershed entering the Rio Grande and Caballo Reservoir and to determine the influence of Elephant Butte Reservoir on the Hg cycle in Caballo Reservoir.
Dr. Michael Johnson and his graduate assistants have developed new chemical procedures using ferrate [iron(VI)] to remove extremely low concentrations of arsenic and arsenic-containing compounds from water. This report describes the method used by the researchers to determine the ability of ferrate to remediate arsenic. The method provides an inexpensive approach to meet new drinking water regulations where acceptable levels of arsenic may reach as low as 2 ppb.
Based on the information collected during the Las Nutrias Groundwater Project, typical agricultural cropping, water, nutrient, and pesticide management practices do not appear to pose a broad threat to shallow groundwater in the Rio Grande Valley. Due to large dilution by ambient groundwater (whose source includes mountain-front recharge, infiltration losses from the Rio Grande, and recharge from other agricultural fields), temporary spikes in field drainage chemical concentrations are rapidly diluted below regulatory levels.
One hundred years of actual precipitation data collected from Las Cruces were used as an input to a one-dimensional numerical model to explore this concept. Four soil textures were simulated in soil profiles, some barren and some vegetated. Climate conditions supporting the initiation of recharge include both single, very large rainfall events and gradual soil moisture content increases. Recharge periods ended if two consecutive years had below average rainfall. El Nino conditions did not correlate well with the five recharge periods studied, but Eastern Pacific cyclones were responsible for the two single, largest rainfall events, both of which initiated major recharge periods and may be responsible for the continuance of other periods as well.
