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Surface Water Chemistry--Comprehensive Organic Analyses

Organic Nitrogen and Organic Carbon in Hydrologic Systems

Research Problem to be Addressed

Although the fate, transport, and reactivity of dissolved organic nitrogen have been overshadowed by nitrogen cycling studies that focus on inorganic nitrogen, dissolved organic nitrogen is of increasing concern because of its role as a nutrient, a possible cause of eutrophication, and its potential to react with disinfectants to form nitrogenous disinfection by-products. The chemistry of dissolved organic nitrogen is complicated because of the multiple forms of organic nitrogen including both labile and recalcitrant forms. The objective of this project is to understand the fundamental properties of dissolved organic nitrogen in relation to its role in water quality, eutrophication, and disinfection processes. Dissolved organic nitrogen will be investigated in surface waters. Forest fires contribute organic carbon and nitrogen to surface waters. Biomass will be charred under controlled conditions, leached with water, and the organic carbon and nitrogen in these leachates characterized. These studies will provide information on water quality effects from forest fires and incorporation of biochar into soils to enhance soil fertility.

Electrospray ionization/mass spectrometry has been applied for analysis in a variety of applications, and identification was verified by electrospray ionization/tandem mass spectrometry. These new applications of electrospray ionization/mass spectrometry provide a different approach for characterizing water-soluble organic compounds found in the environment. This approach necessitates extensive maintenance to compensate for non-traditional analytical techniques.

Current Projects:

Determination of fuel type of heavily degraded or weathered fuels in fuel spills using unique polar components in the fuel without separation, fractionation, chromatography, quantitation or derivatization of components.

We have found that the polar components in refined hydrocarbon fuels are unique to each fuel type, based on their distillation range (Rostad, 2005; Rostad, 2006; Rostad and Hostettler, 2007). The polar components are the most recalcitrant portion of a fuel released to the environment. Regardless of the extent of weathering, degradation, or water-washing, the polar fraction remained the same, that is, uniquely indicative of diesel fuel. This study was in collaboration with USGS North Dakota Water Science Center.

Determination if drilling fluids have contaminated core samples during USGS Eyreville Corehole Drilling using unique components of drilling fluids in core pore waters.

Studies on the Chesapeake Bay Impact Crater included cores from a wide variety of depths. Pore waters from the cores were used to determine if drilling fluid had contaminated the cores. We found that unique components of the drilling fluids were not present in the pore waters from the cores.

Determination of organic compounds that are contributing to high dissolved organic carbon downstream from lead/zinc mine and milling processes.

Surface-water samples were collected near a lead/zinc mine and mill tailings in Missouri to determine if water-soluble organic compounds could be a cause of documented negative impacts to biota downstream. The reagents used in the milling process of the lead-zinc ore include a wide range of compounds. Water samples contained relatively high dissolved organic carbon for surface waters, but were colorless, which precluded naturally occurring aquatic humic or fulvic acids. A variety of solid phase extractions were used to isolate different types of organic compounds, including focus on the heavily used isopropyl xanthate. We found dioctyl sulfosuccinate, a filtering aid used at the site, and octyl sulfosuccinate, from loss of an alkyl side chain from dioctyl sulfosuccinate. We also found xanthate degradation products that have not been reported downstream from milling areas before.

Effects of Formation Conditions on Biochar

Biochar is the residue from heating biomass without oxygen. Incorporation into soils has been shown to increase soil fertility and crop production while facilitating long-term carbon sequestration. Biochar includes char from plant biomass including cellulose, lignin, switchgrass, pine and poplar wood and bark.

We have found that formation conditions (time and temperature of heating) have a substantial effect on surface area, acid functional groups, and water sorption of the resulting char, independent of source material. The range of heating times and durations produce very complex changes in biochar, and have dramatic effects on water extracts from the biochar as well. We have found that formation conditions also affect the water extracts of biochar and characteristics such as pH, dissolved organic carbon, and molecular weight distributions.

Project Staff:

Colleen E. Rostad
Project Chief
U.S. Geological Survey
P.O. Box 25046, MS 408, DFC
Denver, Colorado 80225
Telephone: 303-236-3971
Fax: 303-236-3934
email Colleen E Rostad
David W. Rutherford
Research Chemist
U.S. Geological Survey
P.O. Box 25046, MS 408, DFC
Denver, Colorado 80225
Telephone: 303-236-3978
Fax: 303-236-3934
email David W. Rutherford

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Project Contact Information:Colleen E. Rostad
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Page Last Modified: October 19, 2009