James S. Carsella

Presence and transport of the antimicrobials triclocarban and triclosan in a wastewater-dominated stream and freshwater environment.

The presence of the antimicrobials triclocarban (TCC) and triclosan (TCS)in Fountain Creek, a wastewater-dominated stream, and the Arkansas River, Colorado, USA was measured in the surface water, suspended sediments, and bed sediments during spring runoff (high flow) and summer base flow (low flow) conditions. Fountain Creak is a tributary of the Arkansas River. Passive polar organic chemical integrative samplers (POCIS) were used along with active sampling (water grab samples) to measure and TCS concentrations in these surface waters. The concentration of TCC and TCS, based on POCIS measurements, ranged from 4.5 to 47.3 ng/L and 3.9 to 28.3 ng/L, respectively, at the five sample sites monitored in this study under both flow conditions. The range of concentrations of TCC and TCS in suspended sediments was 0.7-57.3 ng/g and 0.7-13.3 ng/g, respectively, and was closely tied to the quantity of organic carbon in the suspended sediment, which ranged from 1.6 to 14.5%. The quantity of organic carbon in suspended sediment during the summer base flow was influenced by runoff from the burn area of a large forest fire that occurred between the two sampling periods. The primary transport mechanism of TCC and TCS in these surface waters was in the dissolved phase, with 64-99% of TCC and 68-99% of TCS transported in the dissolved phase. The total amount of TCS and TCC in bed-sediments was relatively low, with the maximum amount at any one site being 0.38 ± 0.15 ng/g TCS and 4.09 ± 5.26 ng/g TCC. Fountain Creek contributed up to 76% and 69% of the TCC and TCS, respectively, that is transported directly below its confluence with Arkansas River. Fountain Creek drained approximately 3.0 g/day TCS (in spring), 2.9 g/day TCS (in summer) and 1.9 g/day TCC (in spring), 2.0 g/day TCC (in-summer) into the Arkansas River, which suggests consistent input of TCC and TCS into Fountain Creek, such as in discharge of treated wastewater that is independent of changing creek flow conditions.

Bioaccumulation of Selenium by the Bryophyte Hygrohypnum ochraceum in the Fountain Creek Watershed, Colorado

Aquatic bryophytes, Hygrohypnum ochraceum, were deployed “in situ” at 14 sites in the Fountain Creek Watershed, spring and fall, 2007 to study selenium (Se) accumulation. Dissolved, total, and pore (sediment derived) water samples were collected and water quality parameters determined while plants were exposed to the water for 10xa0days. There was a trend showing plant tissue-Se uptake with distance downstream and we found a strong correlation between Se in the water with total hardness in both seasons. There was a modest association between Se-uptake in plants with hardness in the spring of 2007 but not the fall. Plants bioconcentrated Se from the water by a factor of 5.8xa0×xa0103 at Green Mountain Falls and 1.5xa0×xa0104 at Manitou Springs in the fall of 2007. Both are examples of the bioconcentration abilities of the plants, primarily in the upper reaches of the watershed where bioconcentration factors were highest. However, the mean minima and maxima of Se in the plants in each of the three watershed segments appeared similar during both seasons. We found direct relationships between the pore and dissolved Se in water in the spring (R2xa0=xa00.84) and fall (R2xa0=xa00.95) and dissolved Se and total hardness in the spring and fall (R2xa0=xa00.92). The data indicate that H. ochraceum was a suitable indicator of Se bioavailability and Se uptake in other trophic levels in the Fountain Creek Watershed based on a subsequent study of Se accumulation in fish tissues at all 14 sites.

Differential Accumulation of Mercury and Selenium in Brown Trout Tissues of a High-Gradient Urbanized Stream in Colorado, USA.

Total mercury (THg) and selenium (Se) were analyzed by Inductively Coupled Plasma Mass Spectrometry in 11 internal and external tissues and stomach contents from 23 brown trout, Salmo trutta, of a 22.9-km reach of a high-gradient stream (upper Fountain Creek) in Colorado, USA, impacted by coal-fired power plants, shale deposits, and urbanization. Trout and water were sampled from four sites ranging from 2335 to 1818xa0m elevation. Lengths, weights, and ages of fish between pairs of the four sites were not significantly different. The dry weight (dw) to wet weight (ww) conversion factor for each tissue was calculated with egg-ovary highest at 0.379 and epaxial muscle fourth highest at 0.223. THg and Se in stomach contents indicated diet and not ambient water was the major source of Hg and Se bioaccumulated. Mean THg ww in kidney was 40.33xa0µg/kg, and epaxial muscle second highest at 36.76xa0µg/kg. None of the tissues exceeded the human critical threshold for Hg. However, all 23 trout had at least one tissue type that exceeded 0.02xa0mg/kg THg ww for birds, and four trout tissues exceeded 0.1xa0mg/kg THg ww for mammals, indicating that piscivorous mammals and birds should be monitored. Se concentrations in tissues varied depending on ww or dw listing. Mean Se dw in liver was higher than ovary at the uppermost site and the two lower sites. Liver tissue, in addition to egg-ovary, should be utilized as an indicator tissue for Se toxicity.

Selenium speciation in the Fountain Creek Watershed and its effects on fish diversity

Se is an environmental concern as it can be toxic if present in high concentrations even though it is a dietary requirement for all animals. Se levels are a special concern in the Fountain Creek Watershed located in southeastern Colorado whose geological source is the Se-rich Pierre Shale. Segments of Fountain Creek have Se water levels that exceed the current EPA limit of 5xa0µg/l. In the studies described here, the effects of river water containing selenium were examined on fish populations at different sites along the Fountain Creek Watershed. Based on the hypothesis that high levels of Se present in the Creek and resident bryophytes should be an indicator of diversity in the river fish we explored the possibility that the low toxicity of the selenium could be due to speciation. A speciation analysis was conducted to determine the selenium(IV) and selenium(VI). Our results show that sites with higher ratios of the more toxic Se(IV) relative to total selenium exhibit lower fish diversity and numberxa0of fish. Our results indicate that factors, other than total Se, such as Se speciation may be involved in controlling the bioavailability and toxicity of this element to aquatic organisms in Fountain Creek.

Mercury and selenium in fish of Fountain Creek, Colorado (USA): possible sources and implications

Fountain Creek in Colorado USA is a major tributary that confluences with the Arkansas River at Pueblo, Colorado, the result being the tributary’s influence on Arkansas River water quality affecting down-stream users. In a previous study, we found that bryophytes (aquatic plants) accumulated selenium in Fountain Creek watershed and this finding prompted us to investigate the extent of the metalloid in the whole-body tissues of fish. One hundred 11 fish (six species) were collected and analyzed for Se by inductively-coupled plasma emission mass spectrometry. Analysis of all analytical data also showed mercury in all of the fish whole bodies and selected tissues. There was a general increase in selenium but a decrease in mercury in fish with downstream travel-distance. The highest whole-body selenium was in Pueblo, Colorado (3393xa0µg/kg, dry weight; 906xa0µg/kg, wet weight); the highest mercury in fish was in the Monument Creek tributary north of Colorado Springs, Colorado (71xa0µg/kg, dry weight; 19xa0µg/kg, wet weight). In four tissues of 11 female fish captured, selenium was highest in the livers at eight sites but highest in the ovaries at three sites. Mercury was highest in the epaxial muscle at all sites. Selenium availability could be due to the watershed lithology and land uses; however, mercury could be carried by atmospheric deposition from coal-fired power plants and historic mining activities. Selenium in fish tissues and water samples were compared to U.S. national water quality criteria.

Selenium Speciation in the Fountain Creek Watershed (Colorado, USA) Correlates with Water Hardness, Ca and Mg Levels

The environmental levels of selenium (Se) are regulated and strictly enforced by the Environmental Protection Agency (EPA) because of the toxicity that Se can exert at high levels. However, speciation plays an important role in the overall toxicity of Se, and only when speciation analysis has been conducted will a detailed understanding of the system be possible. In the following, we carried out the speciation analysis of the creek waters in three of the main tributaries—Upper Fountain Creek, Monument Creek and Lower Fountain Creek—located in the Fountain Creek Watershed (Colorado, USA). There are statistically significant differences between the Se, Ca and Mg, levels in each of the tributaries and seasonal swings in Se, Ca and Mg levels have been observed. There are also statistically significant differences between the Se levels when grouped by Pierre Shale type. These factors are considered when determining the forms of Se present and analyzing their chemistry using the reported thermodynamic relationships considering Ca2+, Mg2+, SeO42−, SeO32− and carbonates. This analysis demonstrated that the correlation between Se and water hardness can be explained in terms of formation of soluble CaSeO4. The speciation analysis demonstrated that for the Fountain Creek waters, the Ca2+ ion may be mainly responsible for the observed correlation with the Se level. Considering that the Mg2+ level is also correlating linearly with the Se levels it is important to recognize that without Mg2+ the Ca2+ would be significantly reduced. The major role of Mg2+ is thus to raise the Ca2+ levels despite the equilibria with carbonate and other anions that would otherwise decrease Ca2+ levels.

Species Richness, Diversity, and Ecology of Chironomidae (Diptera) in Fountain Creek: A Colorado Front Range Sandy-Bottom Watershed

Abstract. The primary purpose of this study was to assess the chironomid species diversity of a high-gradient sandy-bottom watershed along the Colorado Front Range. Adult male Chironomidae were collected concurrently in 2007 and 2008 from 14 sites in the Fountain Creek Watershed (FCW), south central Colorado, USA, using ultraviolet night lights and sweep netting methods. Species-level identifications resulted in 151 species including 24 new species from 65 genera and 6 subfamilies. Forty species are reported here as new Colorado records, and many North American range extensions were recorded. Some species had geographical ranges that included the Neotropical, Afrotropical or Oriental regions. Species from high elevations and northern latitudes were common. Individual species accounts include annotated North American distributions, associated water quality and sediment (particle size) analyses for each site, and ecological notes. Species richness calculations using Jaccard and Sørensen similarity indices indicated, with some exceptions, that sites in closest proximity shared the most common species. Chironomus decorus was the most commonly collected species in the FCW, occurring at 13 of 14 sites; the orthoclad Cricotopus infuscatus was collected at 12 of the sites. In 2007–2008, the FCW had a very diverse chironomid species assemblage. How species composition changes in the watershed will be influenced by urbanization, global warming, and increased base flows from water diversions.

Method for Detecting Toxin‐Induced Gamete DNA Damage in Male Rats

Despite the vast amount of literature on studies about the use of reproductive toxicants in laboratory rats as models, there are no reports documenting the detection of direct sperm DNA damage in rats as a result of exposure to a reproductive toxicant. These studies were initiated to develop methodology for detecting and scoring oxidative sperm DNA damage in Wistar rats. The first of four experiments used the basic Comet Assay to compare sperm collected from xanthotoxin‐treated rats with sperm collected from untreated rats to determine if oxidative sperm DNA damage was detectable. No differences were found between images of sperm from treated and non‐treated samples. During Experiment 2, fresh sperm samples from untreated rats were stored in PBS and then reacted with a 100mg/ml solution of xanthotoxin/acetone. Post‐reaction cells were subjected to mechanical sample grinding or incubation with trypsin in an attempt to disrupt the cell capsule. Again, no differences were recorded. Experiment 3 exposed treated and untreated sperm samples to proteinase K for varying time intervals (30 min – 3 hr) in another effort to disrupt the cell capsule. These proved to be promising, although at the time intervals used in Experiment 3, the entire cell was dissolved. A series of tests were then initiated during Experiment 4 to determine the best buffer and reaction time combination. All things were kept identical to Experiment 3 with the exception that samples were taken at more frequent intervals and a different buffer was used with each sample. The buffers used were PBS, TES, and PBS containing Chelex. The best results were obtained with TES at a 55‐minute time interval. The capsule surrounding the spermatatids proved to be very resilient to most digestive and mechanical agents. The enzyme proteinase K proved to be the best means for disrupting the cell capsule. Proteinase K in a TES buffer worked most effectively for detecting and scoring oxidative sperm DNA damage in Wistar rats.