USGS

Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002

By Jennifer T. Wilson

U.S. Geological Survey
Water-Resources Investigations Report 03–4253

In cooperation with the U.S. Environmental Protection Agency, Region 6, Superfund Division


You will need Acrobat Reader to read the PDF version of this report. If you do not have Acrobat Reader, you may download it here:

http://www.adobe.com/products/acrobat/readstep2.html

pdf file (27.9 MB)

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 http://access.adobe.com/.


Abstract

Bottom-sediment cores were collected from four sites in Caddo Lake in East Texas during May 2002 for analyses of radionuclides (for age dating), organochlorine pesticides, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and major and trace elements, and to describe the occurrence and trends of these sediment-associated contaminants. The Goose Prairie Creek and Harrison Bayou sites receive drainage from an area that includes parts of the now-closed Longhorn Army Ammunitions Plant. The mid-lake site is relatively close to dense oil and gas operations in the lake. The Carter Lake site receives minimal discharge from developed areas.

Sediment age (deposition) dates represented in the cores ranged from 1940 to 2002. The only organochlorine compounds detected in all core samples were the DDT degradation products DDE or DDD, and PCB Aroclors 1242, 1254, and 1260 were detected only at the Goose Prairie Creek site. One or more of the DDE concentrations at all sites exceeded a consensus-based threshold effect concentration (on benthic biota), but none exceeded a consensus-based probable effect concentration. The Goose Prairie Creek site had significant downward trends in concentrations of organochlorine compounds, except for no trend in DDE concentrations. The Ammunitions Plant is a possible historical source of the few organochlorine compounds detected at the Goose Prairie Creek and Harrison Bayou sites.

PAH concentrations at all sites were below respective threshold effect concentrations. Highest PAH concentrations at all four sites were of C2-alkylated naphthalenes. Nearly all statistically significant PAH trends in the cores were downward. On the basis of PAH source-indicator ratios, the majority of PAH compounds appear to have originated from uncombusted sources such as leaks or spills from oil and gas operations or vehicles (automobiles, boats, aircraft) in the Caddo Lake area.

Concentrations of several of the eight trace elements with threshold effect concentrations and probable effect concentrations (among 26 analyzed) were above the respective threshold effect concentrations, but all, except one lead concentration at the Goose Prairie Creek site (deposited about 1961), were below respective probable effect concentrations. Among trace element concentrations at the four sites, lead and mercury were consistently relatively high at the Goose Prairie Creek site. Again the Ammunitions Plant, because of its proximity and history of industrial activities, is the suspected primary source. Statistically significant trends in trace element concentrations were mixed, but more were downward than upward.

Computations to indicate the dominant source (atmospheric fallout or drainage area) of mercury to the Caddo Lake sediment core sites (except Carter Lake) indicate that about one-third of the mercury at the Goose Prairie Creek site might result from drainage area sources. No drainage area sources were indicated for the Harrison Bayou and mid-lake sites. Arsenic, cadmium, and zinc concentrations were highest at the Carter Lake site. No relation between the relatively higher trace element concentrations and any potential source of contamination in the Carter Lake drainage area (for example, oil and gas operations, a road, a boat ramp) is indicated.

CONTENTS

Abstract

Introduction

Purpose and Scope

Background

Study Design

Review of Existing Information

Acknowledgments

Methods of Sediment Collection and Analysis

Sediment-Core Collection Method

Sediment-Core Analytical Methods

Sediment-Core Age Dating

Assessing Contaminant Levels

Trend Testing

Sediment-Core Burden and Focusing Factor

Quality Assurance of Chemical Data

Occurrence and Trends

Goose Prairie Creek

Age Dating and Sedimentation Rates

Contaminant Occurrence and Trends

Harrison Bayou

Age Dating and Sedimentation Rates

Contaminant Occurrence and Trends

Mid-Lake

Age Dating and Sedimentation Rates

Contaminant Occurrence and Trends

Carter Lake

Age Dating and Sedimentation Rates

Contaminant Occurrence and Trends

Sediment-Core Burdens, Focusing Factors, and General Sources of Mercury

Comparison of Findings to Those of Other Texas Lakes

Implications of Findings Relative to Drainage Area Sources of Contaminants

Summary

References

Appendixes

1. Descriptions of Sediment Push Cores

1.1 Description of Sediment Push Cores Collected at Caddo Lake, Texas, May 2002

2. Analytical and Trend Testing Results

2.1. Analytical Results for Radionuclides

2.2. Analytical Results for Organochlorine Compounds

2.3. Analytical Results for Polycyclic Aromatic Hydrocarbons

2.4. Analytical Results for Forms of Carbon and Major and Trace Elements

2.5. Analytical Results for Petroleum Biomarkers

3. Quality-Assurance Data

3.1. Quality-Control Samples for Radionuclides

3.2. Quality-Control Samples for Organochlorine Compounds

3.3. Quality-Control Samples for Polycyclic Aromatic Hydrocarbons

3.4. Quality-Control Samples for Forms of Carbon and Major and Trace Elements

3.5. Quality-Control Samples for Petroleum Biomarkers

FIGURES

1–3. Maps showing:

1.
Locations of Longhorn Army Ammunition Plant (LHAAP) and bottom-sediment coring sites sampled in Caddo Lake, Texas, May 2002
2.
Drainage areas of creeks and contaminated or potentially contaminated areas on Longhorn Army Ammunition Plant (LHAAP), Texas, identified by U.S. Army during a public health assessment of the plant in July 1999
3.
Drainage areas of interest defined using digital elevation models and possible sources of contamination (PSOCs) identified by U.S. Geological Survey Source Water Assessment Program in the Caddo Lake, Texas, area

4–15. Graphs showing:

4.
Relation between logarithm of unsupported lead-210 and cumulative dry mass in cores from (a) mid-lake and (b) Carter Lake, Caddo Lake, Texas, May 2002
5.
Mean annual precipitation at National Weather Service station in Karnack, Texas, 1943–97; monthly mean discharge in Big Cypress Creek near Jefferson, Texas, 1930–2000; and daily lakealtitude at Caddo Lake dam, Louisiana, 1932–2000
6.
Concentrations of selected constituents used to compute sediment deposition dates in cores collected at (a) Goose Prairie Creek, (b) Harrison Bayou, (c) mid-lake, and (d) Carter Lake sites, Caddo Lake, Texas, May 2002
7.
Organochlorine pesticide (DDE and DDD) and polychlorinated biphenyl (PCB) concentrations in cores collected from Caddo Lake, Texas, May 2002
8.
Selected polycyclic aromatic hydrocarbon (PAH) concentrations and trends in core collected near Goose Prairie Creek, Caddo Lake, Texas, May 2002
9.
Selected trace element concentrations and trends in core collected near Goose Prairie Creek, Caddo Lake, Texas, May 2002
10.
Selected polycyclic aromatic hydrocarbon (PAH) concentrations in core collected near Harrison Bayou, Caddo Lake, Texas, May 2002
11.
Selected trace element concentrations and trends in core collected near Harrison Bayou, Caddo Lake, Texas, May 2002
12.
Selected polycyclic aromatic hydrocarbon (PAH) concentrations in core collected in mid-lake of Caddo Lake, Texas, May 2002
13.
Selected trace element concentrations and trends in core collected in mid-lake of Caddo Lake, Texas, May 2002
14.
Selected polycyclic aromatic hydrocarbon (PAH) concentrations and trends in core collected from Carter Lake, Caddo Lake, Texas, May 2002
15.
Selected trace element concentrations and trends in core collected from Carter Lake, Caddo Lake, Texas, May 2002

TABLES

1.
Description of sediment box cores collected from Caddo Lake, Texas, May 2002
2.
Constituents and laboratory reporting levels for samples collected from Caddo Lake, Texas, May 2002
3.
Selected consensus-based sediment-quality guidelines used to assess contaminant concentrations in cores collected from Caddo Lake, Texas, May 2002 15
4.
Summary of trend testing results for organochlorine compounds detected in sediment cores from Caddo Lake, Texas, May 2002—Kendall’s tau correlation of concentration with deposition date
5.
Summary of trend testing results for polycyclic aromatic hydrocarbon compounds detected in sediment cores from Caddo Lake, Texas, May 2002—Kendall’s tau correlation of concentration with deposition date
6.
Summary of trend testing results for major and trace elements detected in sediment cores from Caddo Lake, Texas, May 2002—Kendall’s tau correlation of concentration with deposition date
7.
Summary of results of analysis for selected trace elements in sediment cores from Caddo Lake, Texas, May 2002
8.
Sediment focusing data and core burdens for mercury, Caddo Lake, Texas, May 2002
9.
Summary of trace element and selected PAH concentrations and ratio of 2- and 3-ringed to 4- and 5-ringed PAH assemblages in sediment cores from Caddo Lake, Texas, May 2002, from Lake Meredith, Texas, May 1999, and from Cottonwood Bay in Mountain Creek Lake, Texas, May–July 1996

U.S. Department of the Interior, U.S. Geological Survey
Persistent URL: http://pubs.water.usgs.gov/wri034253
Page Contact Information: GS Pubs Web Contact
Last modified: Friday, September 16 2005, 04:23:28 PM
FirstGov button  Take Pride in America button