William D. Taylor

Forms and fate of Cu in a source drinking water reservoir following CuSO4 treatment

Abstract Copper sulfate (CuSO 4 ) application to surface waters for nuisance algae control has been practised for decades, and the practice remains the most effective algicidal treatment for lakes, reservoirs and other managed water bodies. Despite its long history of use, questions remain about the fate of Cu in water bodies receiving CuSO 4 treatment, and the forms and availability of Cu within surface waters subject to high Cu loadings. This study quantifies the fate of Cu following CuSO 4 treatment to Lake Mathews, the terminal reservoir for the Colorado River Aqueduct and one of the source drinking water supply reservoirs for southern California, and evaluated the forms and kinetic lability of Cu in sediment samples. Based upon measured Cu concentrations, flows at the reservoir outlet, and known mass applied during treatment, mass balance calculations indicate that approximately 20% of the Cu was exported from the reservoir over a 70-day period following an 8.85 metric ton CuSO 4 ·5H 2 O treatment on 23 October 1995. Rapid conversion of the dissolved Cu to particulate forms was observed, with significant accumulation of Cu in the sediments. Total sediment Cu contents ranged from approximately 10–600xa0 μ g/g dry-weight basis and decreased with increasing depth within the sediments, qualitatively following known historical Cu inputs to the reservoir. Sequential extraction and desorption kinetic experiments suggest that a significant portion of the sediment-borne Cu is associated with oxidizable and carbonate-bound phases which may release Cu to the water column, although significant release would occur only under extreme changes in water chemistry.

A pseudanabaena species from Castaic Lake, California, that produces 2-methylisoborneol

Abstract Castaic Lake, a large reservoir in Southern California, experienced a two-month episode of the musty-smelling compound 2-methylisoborneol (MIB) in the fall of 1993. MIB levels in the water column reached or exceeded 150 ng/l. A Pseudanabaena bloom coincided with the off-flavor event. Fourteen odorous strains of the cyanobacterium were isolated, and eight of them were analyzed by gas-chromatographic methods to verify the presence of MIB in culture. The concentrations of MIB in culture ranged from 36 to 445xa0 μ g/l. This is the first documented report, to our knowledge, of a major MIB episode in United States drinking water that was attributable to Pseudanabaena , an organism not generally recognized as a taste-and-odor producer.

Effects of oxygen and nitrate on nutrient release from profundal sediments of a large, oligo-mesotrophic reservoir, Lake Mathews, California

Abstract Lake Mathews is a large, oligo-mesotrophic reservoir located in Southern California. The reservoir has elevated levels of nitrate and periodically experiences hypolimnetic anoxia. Experimental sediment-water chamber incubations and reservoir water quality monitoring were conducted to evaluate how oxygen and nitrate in overlaying water affect nutrient release from profundal sediments and internal nutrient loading. In experimental incubations, under nitrate-free anoxic conditions, sediment nutrient release rates were 3.4 ± 0.8 mg-P/m2 ·d for phosphate and 2.8 ± 1.2 mg-N/m2 ·d for ammonia (average ± standard deviation; n = 6). Oxygen repressed phosphate release and greatly diminished ammonia release from sediments in experimental incubations while nitrate only repressed phosphate release. Similar nutrient release dynamics were observed in the reservoir. Nutrient release rates estimated from seasonal nutrient profiles collected from the reservoir were 3.4 mg-P/m2 ·d for phosphate and 2.5 mg-N/m2 ·d for ammonia. Ammonia accumulation in the hypolimnion commenced with the onset of anoxic conditions, but phosphate accumulation did not start until nitrate disappeared from bottom waters approximately 6 weeks later. The time lag decreased total internal phosphorus loading by approximately 25% relative to hypothetical nitrate-free conditions. Laboratory and field data show that both oxygen and nitrate repress sediment phosphate release, likely via the maintenance of an oxidized surficial sediment layer that retains phosphate in iron-oxide complexes. However, only oxygen and not nitrate was effective in decreasing sediment ammonia release, likely by enhancing biological nitrification and assimilation in surficial sediments under oxic conditions. A number of in-lake management strategies have been developed to inhibit internal nutrient loading including calcium nitrate addition, aluminum sulfate addition, and oxygenation. In our view, the deliberate addition of nitrate to lakes and reservoirs poses several risks that must be carefully considered when evaluating strategies to control sediment phosphorus release.

ALUMINUM SULFATE TREATMENT OF A EUTROPHIC RESERVOIR: RATIONALE, APPLICATION METHODS, AND PRELIMINARY RESULTS

ABSTRACT Aluminum sulfate was applied to eutrophic Eau Galle Lake to control internal phosphorus recycling from anoxic sediments for a period of five years, and to provide increased user benefits at a reasonable cost. Treatment dose (11.3 g Al/m2) was based on mass balance estimates of summer Internal phosphorus loading rates; no attempt was made to curtail external loading rates. Phosphorus concentrations in bottom waters, internal phosphorus loading rate, and the abundance of blue-green algae were reduced relative to previous years; however, algal biomass remained relatively high. The proliferation of the dinoflagellate Ceratium hirundinella, a vertical migrator, suggested that these algae may have obtained phosphorus from interflowing river waters having a high nutrient content.

Effects of Alum Treatment on Phosphorus and Phytoplankton Dynamics in Eau Galle Reservoir: A Synopsis

ABSTRACT Eau Galle Reservoir, located in west central Wisconsin, is a small eutrophic flood control impoundment. The reservoir sustains high sediment and associated nutrient loadings from its agricultural watershed. Despite this systems riverine nature, much of the phosphorus accumulated in the water column during the summer derives typically from internal loading. Entrainment of phosphorus in the epilimnion from hypolimnetic sources during weather-induced partial mixing events has encouraged the development of large phytoplankton blooms. In 1986 internal phosphorus loading was substantially reduced by applying alum to profundal sediments. However, this effect was short-lived (< 1 year) because of high rates of sedimentation with probable burial of alum. Phytoplankton production was not diminished by alum treatment, partly because of high rates of external phosphorus loading during the unusually wet summer of 1986. In addition to inputs from the anaerobic hypolimnion, phosphorus is also transported to su...

Distribution of quagga mussel veligers, Dreissena bugensis, in the reservoirs of the Colorado River Aqueduct

Abstract This study examined the distribution of quagga mussel veligers, Dreissena bugensis, in Copper Basin Reservoir and Lake Mathews, the 2 deepest reservoirs on the Colorado River Aqueduct system in California. Density stratification, driven by temperature differences, was a critical factor in controlling vertical distribution of veligers within the water column. Copper Basin Reservoir had the strongest stratification from May to August, with veliger concentrations higher than 80/L near the thermocline but much lower in the epilimnion and hypolimnion. Veliger concentrations were also elevated near the thermocline in Lake Mathews in late summer 2008 and spring 2009, although operation of a bubble aeration system later in 2009 eliminated the strong thermocline and may have influenced veliger abundance generally present there. Average chlorophyll a concentrations were low (<5 μg/L) in both reservoirs, although an increase in chlorophyll a concentration (to ∼10 μg/L) was observed within the spring thermocline in Lake Mathews; a chlorophyll a maximum near the thermocline was not present in Copper Basin Reservoir. These observations suggest that stratification, and not chlorophyll a concentration, determined the vertical distribution of veligers. The thermocline is a zone of increasing density that often concentrates particles. Statistically significant horizontal gradients in veliger concentrations were absent, suggesting that lateral currents mix and distribute veligers across these basins.

Hepatic Copper Concentrations and Condition Factors of Largemouth Bass (Micropterus salmoides) and Common Carp (Cyprinus carpio) from Copper Sulfate-Treated and Untreated Reservoirs

ABSTRACT The application of copper sulfate to surface waters for nuisance algae control has been practiced for decades. Despite its long history of use, questions persist about the fate and bioavailability of copper (Cu) in water bodies receiving copper sulfate applications. This study compares the hepatic Cu content of largemouth bass (Micropterus salmoides) and common carp (Cyprinus carpio) sampled from two reservoirs in southern California with contrasting copper sulfate treatment histories. Lake Mathews is the terminal reservoir for the Colorado River Aqueduct and has received over 2000 tons of CuSO4·5H2O over the past ~20 years. As a result of repeated copper sulfate treatment, Lake Mathews has an average Cu sediment content of 290 μg·g−1 dry weight. Copper Basin Reservoir, also part of the Colorado River Aqueduct system, has not previously received any CuSO4 applications and thus has a much lower sediment Cu content (8 μg·g−1). The mean hepatic Cu content of small bass (mean length ~24 cm) was significantly higher for individuals sampled from Lake Mathews than from Copper Basin Reservoir (22.9±20.5 vs. 4.3±4.4 μg·g−1, respectively), although no statistically significant difference (at p≤0.05) was found for large bass (mean length ~41 cm) from the two reservoirs. The mean hepatic Cu concentration of carp from Lake Mathews was significantly higher (at p≤0.05) than that of carp from Copper Basin Reservoir (76.8±42.3 vs. 51.3±22.4 μg·g−1, respectively). No apparent negative effects associated with copper sulfate application or copper accumulation within fish were found, however, as condition factors (K) for fish from Lake Mathews were either comparable to or higher than those from Copper Basin Reservoir (e.g., for small bass, K was 1.78±0.11 vs. 1.46±0.10, respectively).

Quantifying quagga mussel veliger abundance and distribution in Copper Basin Reservoir (California) using acoustic backscatter

Quagga mussels (Dreissena bugensis) have been linked to oligotrophication of lakes, alteration of aquatic food webs, and fouling of infrastructure associated with water supply and power generation, causing potentially billions of dollars in direct and indirect damages. Understanding their abundance and distribution is key in slowing their advance, assessing their potential impacts, and evaluating effectiveness of control strategies. Volume backscatter strength (Sv) measurements at 201- and 430-kHz were compared with quagga mussel veliger and zooplankton abundances determined from samples collected using a Wisconsin closing net from the Copper Basin Reservoir on the Colorado River Aqueduct. The plankton within the lower portion of the water column (>18 m depth) was strongly dominated by D-shaped quagga mussel veligers, comprising up to 95-99% of the community, and allowed direct empirical measurement of their mean backscattering cross-section. The upper 0-18 m of the water column contained a smaller relative proportion of veligers based upon net sampling. The difference in mean volume backscatter strength at these two frequencies was found to decrease with decreasing zooplankton abundance (r(2) = 0.94), allowing for correction of Sv due to the contribution of zooplankton and the determination of veliger abundance in the reservoir. Hydroacoustic measurements revealed veligers were often present at high abundances (up to 100-200 ind L(-1)) in a thin 1-2 m layer at the thermocline, with considerable patchiness in their distribution observed along a 700 m transect on the reservoir. Under suitable conditions, hydroacoustic measurements can rapidly provide detailed information on the abundance and distribution of quagga mussel veligers over large areas with high horizontal and vertical resolution.