Publications—Water-Resources Investigations Report

Organic and Trace Element Contaminants in Water, Biota, Sediment, and Semipermeable Membrane Devices at the Tres Rios Treatment Wetlands, Phoenix, Arizona

By  Larry B. Barber, Steffanie H. Keefe, Greg K. Brown, Howard E. Taylor, Ronald C. Antweiler, Dale B. Peart, Terry I. Plowman, David A. Roth, and Roland D. Wass 

Water-Resources Investigations Report 03-4129

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ABSTRACT

    The Tres Rios Demonstration Treatment Wetlands located near Phoenix , Arizona are sustained by effluent from the 91st Avenue Wastewater Treatment Plant (WWTP). A series of sampling events were conducted between 1998 and 2000, and the results of organic and inorganic analysis of water, sediment, biota, and semipermeable membrane devices (SPMD) are presented here. The free-water surface wetlands consist of shallow (0.3 meter) zones containing emergent vegetation (softstem bulrush, Schoenoplectus tabernaemontai, and Olney’s bulrush, Schoenoplectus americanus), and deep zones (1.5 m) without vegetation. Conditions ranged from aerobic to anaerobic between the wetland inlet and outlet locations and temperatures were relatively constant, and there was little removal of specific conductance, total and dissolved organic carbon, and major anions and cations. Several pesticides and herbicides were detected in water samples including carbaryl, diazinon, 3,4-dichloroaniline (degradate of linuron and diuron), prometon, and simazine. Volatile organic compounds detected include bromodichloromethane, chloroform, dibromochloromethane, 1,4-dichlorobenzene, methylene chloride, tetrachloroethene, and toluene.

            Concentrations of ethylenediaminetetraacetic acid (EDTA), a metal complexing agent and indicator compound of wastewater-impact, were greater than 100 micrograms per liter (mg/L) in the effluent and were reduced 75% between the wetland inlet and outlet. In contrast, concentrations of nitrilotriacetic acid (NTA), a more biodegradable metal complexing agent, were lower (less than 10 mg/L) and remained relatively stable in the wetlands. Downstream of the 91st Avenue WWTP effluent discharge location, the levels of EDTA in the Gila River decreased by 77% after 12 kilometers (km) of transport.

            Alkylphenolethoxylate (APE) compounds are potential endocrine disrupting chemicals derived from nonionic surfactant degradation and are commonly detected in wastewater effluents. The most abundant APE-derived compounds were nonylphenolethoxycarboxylic acids (NPEC) which are hydrophilic (water soluble) degradates that occur as ionic species. The combined nonylphenolmonoethoxycarboxylate and nonylphenoldiethoxycarboxylate (NP1EC and NP2EC) levels in the effluent were greater than 100 mg/L and decreased 47% and 36%, respectively, in the treatment wetlands. Concentrations of nonylphenoltriethoxycarboxylate and nonylphenoltetraethoxycarboxylate (NP3EC and NP4EC) were lower and relatively stable at the wetland inlet and outlet locations. Combined NP1EC and NP2EC concentrations greater than 50 mg/L were detected in the Gila River 12 km downstream from the 91st Avenue WWTP discharge. Other NPE-derived compounds that were detected include nonylphenol, octyphenol, nonylphenolmonoethoxylate, nonylphenoldiethoxylate, octylphenolmonoethoxylate, and octylphenoldiethoxylate. A variety of other organic wastewater contaminants also were detected, including caffeine, triclosan, and coprostanol.

In 1998, tilapia (Tilapia mossambica) and mosquito fish (Gambusia affinis) collected from the wetlands showed accumulation of p,p’-DDD, p,p’-DDE, and dieldrin. In 2000, Tilapia showed accumulation of p,p’-DDE and trans-nonachlor. Gambusia collected in 2000 had elevated concentrations of cis- and trans-chlordane, p,p’-DDE, dieldrin, lindane, trans-nonachlor, and polychlorinatedbiphenyls. Tilapia appeared to be less susceptible than Gambusia to accumulation of hydrophobic organic compounds (HOC) on a mass basis. Although the lipid content of the Tilapia liver tissue was equivalent to the whole-body Gambusia, concentrations of p,p’-DDE and trans-nonachlor and were 3 to 5 times higher in the whole-body Gambusia than in the Tilapia liver. The absence of contaminants in the Tilapia filet tissue indicates low risk to human populations that eat the fish. In the 2000 sampling, all of the compounds detected in Tilapia were detected in the Gambusia, but the Gambusia also contained additional compounds

            The SPMD showed elevated concentrations of HOC that potentially can bioconcentrate in the lipid of aquatic organisms. SPMD deployed for 28 days in 1998 accumulated cis- and trans-chlordane, p,p’-DDE, dieldrin, endosulfan I, endosulfan II, heptachlor epoxide, hexachlorobenzene, lindane, cis- and trans-nonachlor, oxychlordane, and pentachloroanisole. The SPMD outlet concentrations showed a 70% to >99% reduction relative to inlet concentrations. During 1999, a time-series experiment (SPMD were collected 1, 2, 4, 6, and 8 weeks after deployment) was conducted to determine SPMD uptake rate characteristics in the treatment wetlands. The results indicate that cis- and trans-chlordane, and trans-nonachlor achieved steady state within 28 days, and that consistent with the 1998 results, there was >70% removal across the wetland. Dieldrin, lindane, and pentachloroanisole showed linear uptake during the initial part of the exposure (first 4 weeks) followed by clearance in the later part of the study. Dieldrin concentrations decreased 64% between the inlet and outlet, lindane decreased 37%, and pentachloroanisole decreased >90%. Concentrations of p,p’-DDE in the SPMD increased over time and demonstrated that both internal loading and removal mechanisms were occurring within the wetland.

Both the Gambusia and Tilapia, and the SPMD data indicate accumulation of p,p’-DDE, dieldrin, and trans-nonachlor, whereas the Gambusia and SPMD also accumulated cis- and trans-chlordane, and lindane. The inlet SPMD contained elevated concentrations for each of these compounds relative to the outlet and values measured in the fish tissue. The Gambusia concentrations were generally equivalent to those measured in the outlet SPMD.

            Although there was a slight increase in the wetland outlet concentrations relative to the inlets, the major-ion chemistry indicated little change during wetland treatment. This is consistent with specific conductance results, which are an indirect measure of total dissolved ions. A large suite of dissolved trace elements were detected, and as would be expected, varied significantly in their behavior in the wetlands. For example, dissolved arsenic concentrations in the wetland outlets were similar to (averaged 9% higher) the inlet concentrations, indicating no removal and the slight concentrating effects of evapotranspiration. In contrast, copper underwent significant removal (>90%) during wetland treatment and lead and zinc were removed to a lesser extent (>50%). Some elements such as cadmium and the rare earth elements, had higher concentrations in the outlets than the inlets indicating internal loading.

            The sediment and bulrush vegetation had trace element distributions in general agreement with the water composition, although for many elements, concentrations in the sediment and vegetation were much higher. For example, concentrations of lead, zinc, arsenic, copper, and cadmium were 20, 25, 50, 1000, and 10,000 times higher in the vegetation respectively than in the water.

            Trace element distributions in the fish tissue were similar between the Tilapia and Gambusia whole-body analyses, and were in general agreement with the water composition. The concentrations of most trace elements in the Tilapia filet tissue were very low, whereas concentrations in the liver tissue were an order of magnitude higher.

Methods of data collection and results of analyses are presented for diel water-quality data collected from two nearby agricultural drainages in northwestern Indiana, the Iroquois River and Sugar Creek.  During four separate sampling trips, in June and September 1999, May 2000 and September 2001, 208 discrete water samples were collected to document the aqueous chemistry over the course of 2 to 4 days on each of these drainages. Data were collected for nutrients, dissolved organic carbon, suspended sediment, major inorganic constituents (major cations and anions), trace elements, total bacterial counts, and chlorophyll-a concentrations. In addition, field measurements of water temperature, specific conductance, pH, and dissolved oxygen concentrations were made during all trips.

CONTENTS

Contents
Tables
Figures
Conversion Factors and Abbreviations
Abbreviations
Abstract
CHAPTER 1 - INTRODUCTION
     Purpose and Scope 
     Acknowledgments
     Background
     Site Description
          Hayfield Site
          Cobble Site
     Ecosystem
CHAPTER 2 - SAMPLING APPROACH
     Field Sampling Methods
          Water
          Fish
          Semipermeable Membrane Devices
          Sediment
          Vegetation
     Analytical Methods
          Water
               Field Measurements
               Total and Dissolved Organic Carbon
               Pesticides
               Herbicides
               Volatile Organic Compounds
               Wastewater-Derived Compounds
               Ethylenediaminetetraacetic, Nitrilotriacetic, and Nonylphenolethoxycarboxylic Acids
               Major Cations and Trace Elements
               Anions
               Nutrients
          Fish Tissue and Semipermeable Membrane Devices
               Tissue Processing
               Organic Contaminants
                    Fish Tissue
                    Semipermeable Membrane Devices
               Trace Elements
                    Fish Tissue
                    Vegetation Tissue
          Sediment
                Organic Contaminants
                Trace Elements
CHAPTER 3 - ORGANIC COMPOUNDS IN WATER, BIOTA, SEMIPERMEABLE MEMBRANE DEVICES, AND SEDIMENT
     Water
          Field Measurements
          Total and Dissolved Organic Carbon
          Pesticides, Herbicides and Insecticides
          Volatile Organic Compounds
          Ethylenediaminetetraacetic, Nitrilotriacetic, and Nonylphenolethoxycarboxylic Acids
     Fish Tissue
     Semipermeable Membrane Devices
          1998 Deployment
          1999 Deployment
     Sediment
     Bioaccumulation
CHAPTER 4 - INORGANIC CONSTITUENTS IN WATER, BIOTA, AND SEDIMENT
     Quality Assurance
          Accuracy
          Standard Reference Materials
          Spike Recoveries
          Blanks
          Precision
     Water
          Major Cations and anions
          Trace Elements
          Nutrients
     Sediment
     Biota
          Vegetation
          Fish Tissue
CHAPTER 5 - REFERENCES CITED


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