Should We Put Our Feet in the Water? Use of a Survey to Assess Recreational Exposures to Contaminants in the Anacostia River

Developmental effects of siloxane exposure in zebrafish: a comparison study using laboratory-mixed and environmental water samples

Siloxanes are used in personal care, biomedical, and industrial products. Their worldwide use and persistence in the environment cause consistent exposure for both humans and aquatic animals. Two siloxane congeners, decamethylcyclopentasiloxane (D5; CAS 541-02-6) and octamethylcyclotetrasiloxane (D4; CAS 556-67-2), are among the most prevalent, with measurable levels in air, sediment, water, and biological samples. However, few studies have examined the impact of developmental (embryo/larva) exposure. To address this gap, we performed parallel experiments using wildtype zebrafish (Danio rerio). One set of experiments used laboratory-mixed individual solutions containing either D4, D5, or 2,4,6,8-tetramethylcyclotetrasiloxane (D₄ ^H ; CAS 2370-88-9); the other used environmental water samples containing a mixture of siloxanes, including D4 and D5. These samples were collected from Bladensburg Waterfront Park (BWP) a site along the Anacostia River, Washington, DC. In both experiments, zebrafish (24-48 hours postfertilization, hpf) were exposed until 7 or 14 days (d)pf. Chronic exposure to D4, D5, or BWP water until 7 dpf caused stress-like behaviors and reduced swim velocities; anatomical differences were noted only in BWP-exposed larvae. At 14 dpf, BWP-treated larvae still showed slower swimming velocities and increased immobility; anatomical differences were no longer evident and thigmotactic behavior was reduced. D4 and D5-exposed larvae did not survive after 10 dpf. Larvae exposed to D₄ ^H showed no decreases in behavior or growth at either age. These results suggest early developmental sensitivity to siloxane exposure and point to the need to consider embryonic/larval endpoints when assessing aquatic contaminants.

Distribution, sources and health risk assessment of contaminations in water of urban park: A case study in Northeast China

This case study was performed to determine whether the pollutants in water of urban park could bring health risk to human engaging in water-related activities such as swimming and provide evidence demonstrating the critical need for strengthened recreational water resources management of urban park. TN, NH₄⁺-N, TP, Cu, Mn, Zn, Se, Pb, As, Cd and Cr(VI) contents were determined to describe the spatial distribution of contaminations; sources apportionment with the method of correlation analysis, factor analysis and cluster analysis were followed by health risk assessment for swimmers of different age groups. The results reveal that element contents in all sites do not exceed Chinese standard for swimming area and European Commission standard for surface water; all detected elements except Cr(VI) have a tendency to accumulate in the location of lake crossing bridge; Mn and Zn are considered to have the same pollution source including geogenic and anthropogenic sources by multivariable analysis. Carcinogenic risks of different age groups descend in the same order with non-carcinogenic risks. Among all elements, Zn and Mn contribute the lowest non-carcinogenic risk (5.1940E-06) and the highest non-carcinogenic risk (7.9921E-04) through skin contact pathway, respectively. The total average personal risk for swimmers in swimming area is 1.9693E-03, and this site is not suitable for swimming. Overall, it is possible that swimmers are exposed to risk via the dermal route when carrying out water-related activities, it is recommended that necessary precautions and management should be taken in other similar locations around the world.

Chesapeake Bay's "forgotten" Anacostia River: eutrophication and nutrient reduction measures

The Anacostia River, a Chesapeake Bay tributary running through Washington, D.C., is small but highly polluted with nutrients and contaminants. There is currently a multi-billion dollar tunnel project underway, being built in several phases, aimed at diverting effluent to sewage treatment, especially during high flow periods, and improving water quality of the Anacostia and the river into which it flows, the Potomac. Here, 4 years of biweekly to monthly nutrient and phytoplankton data are analyzed to assess pre-tunnel eutrophication status and relationships to flow conditions. Under all flow conditions, nutrients prior to tunnel implementation were well in excess of values normally taken to be limiting for growth, and hypoxia was apparent during summer. Chlorophyll a was higher in summer (averaging 26.9 μg L^-1) than in spring (averaging 14.8 μg L^-1), and based on pigment composition, summer communities had proportionately more cyanobacteria (> 2-fold higher zeaxanthin to chlorophyll a ratios) compared to spring, which had proportionately more diatoms (> 2-fold higher fucoxanthin to chlorophyll a ratios). When all data from all years and sites were considered, there was a decrease in diatoms and increase in cyanobacteria with decreasing NO₃^- and increasing NH₄⁺ concentrations, increasing ratios of NH₄⁺ to NO₃^-, and increasing temperature. Tunnel implementation and associated nutrient reductions may reduce the severity of summer blooms but reductions of spring assemblages may be even greater because river flows are typically higher at that time of year.