Analytical Chemistry

Research activities include the development of technology for the field sampling and laboratory measurement of ultra-trace concentrations of constituents in hydrologic systems using state-of-the-art analytical laboratory instrumentation.

1. Two decades of pioneering development of inductively coupled plasma-atomic emission and inductively coupled plasma-mass spectrometric techniques, including sample introduction methods, has been accomplished for the ultra-low concentration determination of trace elements in water quality and environmental materials.
2. Techniques and methodology were developed for the measurement of stable isotope ratios of selected heavy metals and rare-earth elements at trace (microgram/liter) concentration levels in natural waters for use as chemical and hydrologic tracers and for isotope-dilution quantitation. Research in instrumentation modifications continue to be investigated to improve isotope ratio measurement precision, stability and sensitivity.
3. Research continues in the development of techniques using sedimentation-field flow fractionation coupled with ICP-MS (SdF³-ICP-MS) for the study of the geochemistry of trace elements associated with colloidal and sub-micrometer diameter suspended particulate material in natural surface water systems. In addition, this technique is being used to evaluate and study the transport and fate of heavy metal contaminants in hydrologic systems associated with sorption on the surfaces of suspended particulate matter.

Water Quality and Trace Element Geochemistry Studies

Research into the occurrence, distribution, geochemistry and fate of trace elements continues to be carried out at several field locations, selected for their unique chemical or hydrologic characteristics.

Mississippi River

Research continues to be performed on the water and sediment chemistry (focusing on trace elements, including Hg and nutrients) in the Mississippi River system. This includes the investigation of interaction of trace metals with other water chemical constituents (with emphasis on the distribution between various size fractions of suspended material, silts, colloids, and bed sediments). Field studies are being carried out to determine interactions of contaminants with each other and suspended sediment at "primary mixing zones" below confluences of tributaries. This research includes studies of bed sediment materials and pore water samples. Sequential extraction techniques were developed for the study of the partitioning of trace elements between the various chemical fractions in the sediment materials. Results of a research study on the changes in water quality of the Mississippi River during the 1993 flood has been interpreted and published. Data from research studies on the changes in sediment chemistry is currently under interpretation and will be published when completed.

Lake Powell and the Colorado River

Research continues involving the study of the water quality and water chemistry of the Colorado River system and the impacts from Glen Canyon Dam operation on the ecology and water quality of the river systems in Grand Canyon National Park. This included the interpretation of data collected from two large scale synoptic sampling studies in November 1990 and June 1991. Results of this research will assist in developing an understanding of the occurrence, distribution and chemistry of water quality constituents related to controlled and variable hydrologic discharge and impacts from tributary contributions. Studies were undertaken to establish the chemical water quality of tributaries to the Colorado River in the Grand Canyon to develop an understanding of the ecological impacts of land use in the water sheds of the tributaries. Mixing processes below confluences of these tributaries are being studied. A report on the two synoptic studies is in process.

Studies continue to evaluate the occurrence, distribution and interaction of trace elements in the delta sediments in the Colorado River and San Juan River arms of the Lake Powell reservoir. These studies involve developing sampling techniques and statistically determining the spatial distribution of sediment trace metal contamination in Lake Powell. Results of this study will be used to evaluate the redistribution of contaminants in the reservoir.

A research project is underway to study the water quality, using state-of-the-art technology, of springs and seeps on a temporal and spatial basis in the Glen Canyon National Recreation Area in collaboration with the National Park Service. The purpose of this study is to establish baseline concentration levels of chemical constituents in springs and seeps used as drinking water sources and correlate these concentrations with geological formations and land use activities (mining, cattle grazing, etc.). Results of this study will be used to establish a long term monitoring program.

Nitrogen Transformation in the Upper Mississippi River

Many of the tributaries in the Upper Mississippi River Basin are contaminated with nitrogen compounds (chiefly nitrate) derived primarily from agriculture. Collaborative research is underway to determine the fate and transport of these nitrogen compounds in these tributaries, especially as they relate to nitrogen transformation reactions; the results of this work are potentially of great importance to developing remediation techniques for the hypoxic (low-oxygen) zone which occurs annually in the Gulf of Mexico and which threatens the Gulf Coast fisheries there.

Rio Grande

Studies are underway in collaboration with the National Water Quality Assessment Program to understand the distribution, fate and impact on water quality of trace metals in the Rio Grande in southern Colorado and northern New Mexico as influenced by mining and agricultural activities in the drainage system.

Rocky Mountain Snowpack

Research continues, in collaboration with U.S. Geological Survey-Colorado District personnel, to study the spatial and temporal distribution of trace elements and the chemistry of snowpack samples collected from selected locations in the Rocky Mountains, ranging from the Canadian border to New Mexico. Results, correlated with meteorological data, will be used to determine potential sources of atmospheric contaminants.

Yellowstone Park

Research continues to measure the relationship between water chemistry constituents originating from geothermal sources and the occurrence and distribution of benthic invertebrates and fish populations in rivers and streams. Field studies continue in the Gibbon and Firehole Rivers in Yellowstone National Park.

Multi-year long-term research studies were initiated to assess the chemical and biological water quality of the surface waters in Yellowstone National Park using state-of- the-art field and ultra-trace laboratory measurement techniques with the ultimate goal to create a hydrologic water quality atlas, establishing baseline data for long-term monitoring programs.

Lake Kinneret (Sea of Galilee)

Collaborative research studies with the Geological Survey of Israel involving trace element geochemistry and water quality in Lake Kinneret (Sea of Galilee) continue. Spatial and temporal distribution of trace elements in this important drinking water supply are being studied and published.

Venezuela

Research is underway in collaboration with the U.S. Forest Service, to assist the Venezuelan government in studying the occurrence and distribution of mercury from placer gold mining activities in major rivers in tropical rain forests. Studies of the trace element geochemistry of waters originating from the Guyana Shield are continuing.

Sacramento River

Begin trace element water quality studies in the Sacramento River in collaboration with the U.S. Geological Survey-California District. Studies will include the evaluation of acid mine drainage inputs from the Iron Mountain area.

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