Lake Mead Science Symposium Concurrent Sessions
Emerging Issues Abstracts
Limnology and Water Quality Abstracts
Aquatic Biota and Fisheries Abstracts
Riparian and Shoreline Resources Abstracts
1:20 – 1:40 pm
Pharmaceuticals in Waste Streams and Surface Waters of the Colorado River Basin
Sanchez, Charles A-1, Jones-Lepp, Tammy-2, Wilson, Doyle-3,Alvarez, Dave-4, (1) University of Arizona (2) U.S. EPA, National Exposure Research Laboratory (3) City of Lake Havasu (4) USGS Columbia Environmental Research Center
A number of pharmaceuticals have been detected in surface waters across the United States. The objective of this study was to evaluate the presence of selected pharmaceuticals (macrolidic antibiotics and pseudoephedrine) and illicit drugs (methamphetamine, Ecstasy) in surface waters of the Colorado River basin. Grab samples were collected spatially and temporally from waste stream tributaries and receiving surface waters within the basin in Colorado, Utah, Nevada, Arizona, and California. At selected locations we also used time-weighted polar organic chemical integrative samplers (POCIS). Grab samples were prepared for analysis using an automated extractor (AutoTrace, Caliper Life Sciences) with Oasis MCX cartridges (Waters Corp.), subsequently extracted with 5-mLs of 80:20:1 methyl tertbutyl ether/methanol/acetic acid, and 5 mLs 99:1 methanol/acetic acid, and reduced to 0.5 mL using an automated evaporator (TurboVap-Zymark, Caliper Life Sciences). Recovery of the analytes from the POCIS sorbent was achieved by transferring the sorbents into glass gravity-flow chromatography columns fitted with glass wool plugs and stopcocks. Methanol was used to elute the pharmaceuticals from the sorbent. All extracts were analyzed with a Varian 500MS ion trap mass spectrometer by performing real-time mass analyses of LC eluents. One or more of the pharmaceuticals and/or illicit drugs evaluated were found in urban waste streams at concentrations sometimes exceeding 500 ng/L. However, amounts found in the main surface water channels, including the Colorado River, were always below 10 ng/L and most frequently below detection.
1:45 – 2:05 pm
Use of Passive Samplers for Assessing Synthetic Organic Contaminants in Lake Mead National Recreation Area, Nevada and Arizona, USA
Goodbred, Steven L.; Rosen, Michael R.; Alvarez, David A.; and Leiker, Thomas J., U.S. Geological Survey
Many synthetic organic compounds (SOCs) pose potential toxicity to aquatic biota. Approximately 650,000 m3/day of tertiary treated wastewater from the Las Vegas metropolitan area flows through Las Vegas Wash (LVW), into Las Vegas Bay (LVB) which is part of Lake Mead National Recreational Area (LMNRA). Other sources of SOCs include irrigated-urban runoff, storm-water runoff, subsurface inflow and accidental spills. A wide variety of SOCs have been previously found in bottom sediment, fish tissue, and water in LMNRA. Passive samplers were deployed in LMNRA to determine spatial distribution and potential SOC sources. A commonly used musk fragrance, galaxolide, was found in LVB at a higher concentration (90 ng/L) compared to other compounds detected (generally <2 ng/L), followed by another musk fragrance, tonalide (9.5 ng/L). Both compounds were only detected in LVW downstream of effluent outfalls (galaxolide, 400 ng/L; tonalide, 41 ng/L). Galaxolide was detected at a low concentration (1.3 ng/L) in Boulder Basin (≈20 km from most upstream detection), but was not detected below Hoover Dam. Other SOCs detected, including legacy organochlorine compounds, were at much lower concentrations (<1 ng/L) but were detected at more sites. The spatial distribution of compounds detected indicates that the main source of SOCs is from LVW, but there are other sources within LMNRA . Evidence of endocrine disruption in several species of fish has been observed in LMNRA, including altered reproductive hormones, reduced gonadal development, and lower sperm quality indicating exposure to endocrine disrupting compounds.
2:10 -2:30 pm
Occurrence of Pharmaceuticals, Personal Care Products, and Potential Endocrine Disrupting Compounds in Lake Mead, NV
Trenholm, Rebecca A.; Vanderford, Brett J.; Zeigler-Holady, Janie C.; Snyder, Shane A., Southern Nevada Water Authority
Emerging contaminants such as pharmaceuticals, personal care products, pesticides and potential endocrine disrupting compounds are of concern as many of these could potentially exhibit health effects on wildlife at low concentrations. Many of these compounds enter the Lake Mead eco-system as a result of incomplete removal from wastewater treatment processes via the Las Vegas Wash. In an effort to better understand their occurrence and fate in Lake Mead, advanced analytical methods were developed for 51 emerging contaminants, which were used to monitor their concentrations. Water samples were collected from Lake Mead, the Las Vegas Wash and from the Colorado River, just below the Hoover Dam over a course of 2 years. Target compounds were extracted by automated solid phase extraction and analyzed by GC-MS/MS and LC-MS/MS. Most compounds were quantified by isotope dilution with method reporting limits ranging from 0.2 to 120 ng/L. More than 50% of the compounds were detected in Las Vegas Wash samples. However, less than 20% of the compounds were detected in samples collected from the Colorado River downstream of the Hoover Dam and were at concentrations close to method reporting limits. Several contaminant concentrations were graphed to show how the plume of wastewater effluent exiting the Las Vegas Wash mixes with the lake water and is further carried down the Colorado River.
2:35 – 2:55 pm
Mercury Concentrations in Muscle Tissue from Sportfish in Lake Mead, Nevada
Kramer, Joanna; Gerstenberger, Shawn; and Cross, Chad, University of Nevada, Las Vegas
Lake Mead is the largest man-made reservoir in the United States and provides fishing opportunities for numerous anglers. Considerable attention has been given to the bioaccumulation of methylmercury in fish tissues, however, no formal study utilizing approved EPA methodology has been conducted to quantify the amount of mercury present in fish tissue from Lake Mead. The purpose of this study is to determine the concentrations of mercury present in the most commonly consumed fish from Lake Mead and to identify if any of the 4 major basins contain fish with elevated concentrations of mercury. Largemouth bass (n=30), striped bass (n=90), channel catfish (n=44), and blue tilapia (n=31) were collected from selected sites in Boulder Basin, Overton Arm, Virgin Basin, and Gregg Basin of Lake Mead by gill netting or electrofishing. Muscle tissue was homogenized, digested, and analyzed for mercury in accordance with EPA Method 245.6 which must be used to construct human health based fish consumption advisories. Initial findings indicated that mean mercury concentrations were 0.075± 0.044 ppm, 0.146± 0.103 ppm, and 0.093±0.075 ppm in largemouth bass, striped bass, and channel catfish, respectively. Mercury concentrations in blue tilapia were below the detectable limit for this method and therefore were not included in statistical analysis. Preliminary analyses indicated a significant difference (p= 0.001, F= 7.18) between mercury values among the three species. Post-hoc analysis indicated that striped bass contained significantly more mercury (p= 0.003) than largemouth bass but no significant difference was found in channel catfish. In the preliminary data, no significant difference (p= 0.026, F= 3.19) was found between mercury concentrations in fish collected from each of the four basins.
3:25 – 3:45 pm
Study of Male Fish Gamete Quality to Assess Fish Health in Lake Mead National Recreation Area (2007)
Jenkins, Jill A.-1, Patino, Reynaldo-1; Goodbred, Steven L.-1; Eilts, Bruce E.-2; Draugelis-Dale, Rassa O.-1; Orsak, Erik L.-3; Rosen, Michael-1 (1) U.S. Geological Survey, (2) Louisiana State University, and (3) U.S. Fish and Wildlife Service
Animal survival, growth, and reproduction are essential parameters in environmental assessments. A measure of reproductive performance is gamete quality, relating to fertility. From 2006-2008, gamete quality was assessed in the Lake Mead National Recreation Area (LMNRA) using a recreational species, largemouth bass (Micropterus salmoides), endangered razorback suckers (Xyrauchen texanus), and common carp (Cyprinus carpio). In 2007, carp (n=11 to 15 per site), a subsample of a larger population (n=200), were collected from Overton Arm (OA, reference), Las Vegas Bay (LVB), Las Vegas Wash (LWV), and Willow Beach (WB) to investigate possible differences among sites. A significant site difference (P<0.0001) was noted in gonadosomatic index (GSI), where OA=LVB>LVW=WB. Exposure to EDC has been shown to negatively impact GSI, including previous studies with carp in LMNRA. Significantly lower mitochondrial membrane potential and higher percentages of apoptotic spermatazoa were noted at WB than at the other sites (P=0.0056; P<0.0001), respectively. Sperm counts were significantly higher at OA than at LVW (P=0.0270), with all other sites statistically intermediate, OA>(LVB=WB)>LVW. A number of studies have shown that exposure to EDC lowers sperm count which decreases fertilization rates. Sperm DNA fragmentation was higher at WB and LVW than at OA and LVB (P=0.0009). Sperm motility patterns, as measured by computerized sperm motion analysis, were not different. These gamete quality biomarker data were in general accord with endocrine and histological effects observed from the larger population of carp.
3:50 – 4:10 pm
Gonadal and Endocrine Condition of Male Common Carp in the Lake Mead National Recreation Area (2007-2008)
Patiño, Reynaldo-1, Goodbred, Steven L. -1, Orsak, Erik-2, Jenkins, Jill A.-1, Rosen, Michael R. 1, (1) U.S. Geological Survey and (2) U.S. Fish and Wildlife Service
In Lake Mead National Recreation Area (LMNRA), Las Vegas Bay (LVB) receives municipal wastewater effluent, urban runoff, and resurfacing groundwater from the Las Vegas metropolitan area via the Las Vegas Wash (LVW). To examine potential effects of these anthropogenic inputs on fish condition within LMNRA, male common carp (Cyprinus carpio) were collected at four sites [Overton Arm, OA (reference site); LVB; LVW; and Willow Beach, WB] through one reproductive cycle (March, July, November 2007; March 2008) for determination of gonadal (reproductive) and endocrine status. OA males generally had higher gonadosomatic indices (gonad size), higher plasma 11-ketotestosterone (KT) and estradiol-17β (E2), and lower E2/KT ratio (except for WB, with ratios similar to OA). Fish condition in LVB seemed to be intermediate between OA and LVW, indicating a possible gradient of environmental effects within the lake. The condition of males at WB (downstream of Hoover Dam) generally deviated from the reference condition (OA) even more than males from LVW. Although seasonal patterns were evident for all four endpoints in OA and LVB males, no seasonal patterns were seen for KT and E2/KT ratios in LVW males, and no seasonal patterns were observed in WB males. In conclusion, the reproductive and endocrine status of male carp in LMNRA can be classified from high to low according to study site as follows: OA>LVB>LBW>WB. Insights concerning the nature of the factors responsible for site-dependent differences in the condition of male carp within LMNRA await the completion of ongoing physicochemical characterizations of the aquatic habitats.
4:15 – 4:35 pm
Low-level Emerging Contaminants in Lake Havasu, Arizona and California and their Access to Lake Havasu City's Drinking Water Supply
Wilson, Doyle C. -1 and Lepp-Jones, Tammy L.- 2, (1) City of Lake Havasu, Lake Havasu, AZ and (2) U.S. Environmental Protection Agency
In preparation of a wastewater effluent re-charge and recovery program involving alluvial fan sediments, the City of Lake Havasu initiated a survey to evaluate possible waterborne sources of emerging contaminants in the water/wastewater distribution cycle. This distribution cycle includes Lake Havasu water (raw and treated well water), treated wastewater, and ambient groundwater where effluent injection and subsequent groundwater withdrawals will take place. The results from Lake Havasu (raw and treated) water analyses are discussed here. Grab samples were taken once per quarter over a year and were analyzed by liquid chromatography-mass spectrometry (LC-MC) at Southern Nevada Water Authority's (SNWA) River Mountain Research Facility and at the U.S. Environmental Protection Agency's (EPA) Las Vegas National Exposure Research Laboratory (NERL). Several pharmaceutical compounds (atenolol, caffeine, carbamazepine, dilantin, meprobamate, primidone, and sulfamethoxazole), the herbicide atrazine, and the insect repellent DEET have been consistently present in ultra-low concentrations (ng/L range) in the Colorado River, above the urbanized areas of Lake Havasu and in Lake Havasu's Thompson Bay adjacent to Lake Havasu City. Further, the concentrations of these compounds at each of the two locations are comparable, and vary little seasonally. Several other compounds analyzed such as MDMA and TCEP are more episodic. Raw source well water, which has filtered through at least 80 feet of subsurface gravels and sands below the lake bottom, contains six of the above compounds, of which sulfamethoxazole is apparently extracted during the city's biological manganese removal, potable water treatment process. Concentrations of the other five constituents in the finished treated water are largely unchanged.
4:40 – 5:00 pm Panel Discussion