By Brian A. Bergamaschi, Erica Kalve, Larry Guenther, Gregory O. Mendez, and Kenneth Belitz
U.S. GEOLOGICAL SURVEY
Water–Scientific Investigations Report 2005-5152 (ONLINE
ONLY)
Sacramento, California 2005
Complete accessible text of report (4.9 MB PDF)
To view PDF documents, you must have the Adobe Acrobat Reader (free from Adobe
Systems)
installed on your computer.
(download free copy of Acrobat
Reader).
The ability to rapidly, reliably, and inexpensively characterize sources of dissolved organic material (DOM) in watersheds would allow water management agencies to more quickly identify problems in water sources, and to more efficiently allocate water resources by, for example, permitting real-time identification of high-quality water suitable for ground-water recharge, or poor-quality water in need of mitigation. This study examined the feasibility of using easily measurable intrinsic optical properties—absorbance and fluorescence spectra—as quantitative indicators of DOM sources and, thus, a predictor of water quality. The study focused on the Santa Ana River Basin, in southern California, USA, which comprises an area of dense urban development and an area of intense dairy production. Base flow in the Santa Ana Basin is primarily tertiary treated wastewater discharge. Available hydrologic data indicate that urban and agricultural runoff degrades water quality during storm events by introducing pathogens, nutrients, and other contaminants, including significant amounts of DOM. These conditions provide the basis for evaluating the use of DOM optical properties as a tracer of DOM from different sources.
Sample spectra representing four principal DOM sources were identified among all samples collected in 1999 on the basis of basin hydrology, and the distribution of spectral variability within all the sample data. A linear mixing model provided quantitative estimates of relative endmember contribution to sample spectra for monthly, storm, and diurnal samples. The spectral properties of the four sources (endmembers), Pristine Water, Wastewater, Urban Water, and Dairy Water, accounted for 94 percent of the variability in optical properties observed in the study, suggesting that all important DOM sources were represented. The scale and distribution of the residual spectra—that not explained by the endmembers— suggested that the endmember spectra selected did not adequately represent Urban Water base flow. However, model assignments of sources generally agreed well with those expected, based on sampling location and hydrology. The results suggest that with a fuller characterization of the endmember spectra, analysis of optical properties will provide rapid quantitative estimates of the relative contribution of DOM sources in the Santa Ana Basin.
Abstract
Introduction
Purpose and Scope
Background
Acknowledgments
Study Area Description
Sampling and Analytical Methods
Dissolved Organic Material
Ultraviolet Absorbance
Fluorescence
Data Analysis
Definitions
Excitation/Emission Pairs
Specific Ultraviolet Absorbance (SUVA)
Specific Fluorescence Intensity
Modeling
Results and Discussion
Model Endmember Selection
Model Response to Blank and Replicate Samples
Diurnal Variation
Large-Scale Trends
Results from Monthly Sampling
South Fork of the Santa Ana River
Mentone
Warm Creek
Metropolitan Water District Crossing
Cucamonga Creek at Highway 60
Inland Empire Utilities Agency Reclamation Plant 1
Cucamonga Creek near Mira Loma
Prado
Santa Ana River at Imperial Highway
Results from Storm Sampling
Results from Comparison to Common Materials
Results from Data Reduction
Evaluation of Results
Conclusions
References Cited
Document Accessibility: Adobe Systems Incorporated has information about PDFs and the visually impaired. This information provides tools to help make PDF files accessible. These tools convert Adobe PDF documents into HTML or ASCII text, which then can be read by a number of common screen-reading programs that synthesize text as audible speech. In addition, an accessible version of Acrobat Reader 5.0 for Windows (English only), which contains support for screen readers, is available. These tools and the accessible reader may be obtained free from Adobe at Adobe Access.
| AccessibilityFOIAPrivacyPolicies and Notices | |
  |
|