Research Projects 2006

• Assessment of Waterborne Contamination with Human Pathogens in Tributaries of the Anacostia River Using the Asiatic Clam (Corbicula fluminea)
• Effect of Best Management Practices on contaminant levels in storm water runoff to the Anacostia River
• Nutrient flow and biological dynamics in the Anacostia River
• Silica and Siliceous Surfaces as Hosts for Hazardous Metals in Water
• Wet-Weather Flow Characterization for the Rock Creek through Monitoring and Modeling

Assessment of Waterborne Contamination with Human Pathogens in Tributaries of the Anacostia River Using the Asiatic Clam (Corbicula fluminea)

Principal Investigator:      Thaddeus K. Graczyk, MSc, PhD

The highly polluted 10 km freshwater Anacostia River estuary is the largest water body of Washington, DC, and a focus of environmental concerns. It runs along the lower third of the District and essentially separates Federal buildings and upscale housing from the poorer and mostly minority communities in the south and west districts. The Anacostia has been termed one of three Areas of Concern in the Chesapeake Bay and one of the 10 worst American Rivers. The District of Columbia is making plans for extensive waterfront development (Washington Post 2003) although the poor water quality of the Anacostia River has been known for years (Freudberg et al. 1989). There is a fishing advisory issued based on PCB and chlordane levels (Velinsky and Cummins 1994). The River has high bacterial levels (Washington Post 2004a) and tumors in catfish residing in this river are among the highest in the US (Pinkney et al. 2000, Washington Post 2004b). Anacostia benthic life is very poor and sediments have high levels of toxic contaminants (Velinsky and Ashley 2001; Velinsky et al. 1992; Phelps 1993; AWTA 2002). Amazingly, even with high coliform levels detected at the upper end of the estuary (Maeda and Connolly 2002), there have been no studies on human intestinal waterborne parasites such as Cryptosporidium parvum, Giardia lamblia, and microsporidia (i.e., Encephalitozoon intestinalis, E. hellem, and Enterocytozoon bieneusi) in the Anacostia River or its tributaries. These biological contaminants originate from human and non-human, point and non-point sources as they infect humans, livestock and wildlife (Graczyk et al. 1997a; Graczyk et al. 2004). These category B biodefense pathogens are on the CDC, NIH, and USEPA priority lists, because they significantly contribute (particularly Cryptosporidium) to morbidity of healthy people and mortality of immunosuppressed individuals (Graczyk et al. 1997; Graczyk et al. 2004).

Protozoan parasites could also be contributed by the numerous Canadian geese residing in and visiting the Anacostia River watershed (Graczyk et al. 1998a). Eighty percent of Anacostia’s tributaries are in Maryland. There have been relatively few studies of the tributaries but all suggest they are a major source of the chemical and biological contamination of the tidal River (Gruessner et al. 1997; Coffin et al. 1999; Phelps 2000; Phelps 2002; Warner et al. 1997). The proposed project will assess the contamination of Anacostia tributary first and second order streams with human waterborne parasites using the freshwater Asiatic clam, Corbicula fluminea. Molluscan shellfish are considered an ideal organism to study environmental aquatic health as they filter feed and bioaccumulate rather than detoxify pollutants. Because the Asiatic clam is common, widespread, and resistant to environmental toxicants, it is recommended for freshwater contaminant bioaccumulation studies by the National Water Quality Assessment Program (Crawford and Luoma 1993). Translocated Asiatic clams have been used to detect organochlorines and pesticides (Hartley and Johnston 1983; Colombo et al.1995). Asiatic clams can concentrate important human enteric disease protozoa such as Cyclospora cayetanensis (Graczyk et al. 1998b), Cryptosporidium parvum (Graczyk et al. 1998c) and Giardia lamblia (Graczyk et al. 1997b; Graczyk et al 1999; Graczyk et al. 2003). The nearby Potomac River, a Chesapeake Bay restoration success, has a large Corbicula population (Phelps 1995; Phelps 2002) being used for this study.

The overarching objective of the proposed project is to assess contamination of the MD and DC tributaries to the Anacostia River with human waterborne pathogens using the Asiatic clam (Corbicula fluminea). Specifically we will: 1) Identify the source of human waterborne pathogens in the Anacostia River watershed by involving in the project graduate and undergraduate students; 2) Demonstrate the use of the locally available Corbicula clam to assess contamination of Anacostia watershed tributaries with microbiological contaminants; 3) Bring to the attention of Maryland and the District of Columbia administration and public health officials the necessity for cooperation to resolve the contamination problems of the Anacostia River; 4) Facilitate the development of the best management plan for remediation of the water quality and contamination of the Anacostia River; 5) Publicize the results in the scientific literature among scientific communities and among appropriate local agencies; and 6) Provide training for graduate and undergraduate students of the Johns Hopkins University and University of Maryland, respectively.

Effect of Best Management Practices on contaminant levels in storm water runoff to the Anacostia River

This project is designed to examine the effectiveness of best management practices (BMPs) to retain stormwater pollutants from runoff over impervious surfaces.  The  federal government and local government agencies have funded, and/or partnered with other organizations funded, the construction of many bioretention cells, sand filters, and other BMPs for the prevention of stormwater contaminated runoff in Washington D.C. in an effort to prevent the further degradation of the Anacostia and Potomac Rivers, as well as Rock Creek.  There is a need to further understand how these BMPs are performing, which are the most effective, and if design improvements are possible for future BMP installations.

Combined sewer overflows (CSO) continue to occur throughout major cities in the Northeast, Great Lakes, and Northwest regions of the U.S., primarily as a result of rainwater that is diverted from roads, parking lots, and the roofs of buildings during storm events [1].  The rapid transport of water away from the built environment to natural water bodies has dominated engineering for the past 130 years, since the recognition that pathogens in wastewater caused several human diseases.  In older cities with combined sewers the continued replacement of natural surfaces with impervious ones leads to greater amounts of stormwater runoff.  The contamination of natural water bodies leads to the destruction of habitat potentially leading to negative human health impacts Griesel and Jagals [2].  Developing best management practices to prevent rain water contamination, remove pollutants before the runoff enters the combined sewer system, and retain or detain the movement of water in a decentralized fashion can potentially mitigate CSO events.

Urbanization creates impervious surfaces such as roads, sidewalks, highways, rooftops, and parking lots that result in an increase of stormwater runoff at the expense of infiltration.  The stormwater runoff quickly flows over those impermeable surfaces and accumulates toxic pollutants such as heavy metals [3, 4, 5] generated by automobile use, weathering of building materials and atmospheric deposition Davis et al [6]. A nationwide U.S. urban study showed that heavy metals were by far the most prevalent pollutant constituents of urban stormwater runoff Cole et al [7]. Due to its toxic content, the storm water runoff when discharged to a stream, severely impacts the quality of natural water systems by causing a threat to aquatic life and human health, and also flooding and erosion. As a result, urban stormwater runoff has been identified as one of the most significant water pollution problems in the United States Wiginton et al [8]. To address the problem of surface water pollution from urban stormwater runoff, a number of engineered and managed natural systems have evolved and are being offered as “best management practices” (BMPs) for low impact development.  They are part of the United States Environmental Protection Agency’s (USEPA) effort to regulate the release of pollutants into natural aquatic environments through water quality standards set forth by the National Pollutant Discharge Elimination System (NPDES).  A stormwater BMP is a device, practice, or method used to remove, reduce, retard, or prevent targeted stormwater runoff pollutants from reaching receiving waters in the most cost-effective manner.

Nutrient flow and biological dynamics in the Anacostia River
Principal Investigator:      Stephen E. MacAvoy, Ph.D.

Co-principal Investigators:         Karen L. Bushaw-Newton, Ph.D.

Rivers are longitudinally linked systems with processes occurring in the upper reaches impacting downstream reaches and processes occurring in downstream reaches impacting upstream reaches through biological migration. The Anacostia River is an important link between the terrestrial and aquatic regions of the Potomac watershed and the larger Chesapeake Bay system. Although the health of the Potomac Estuary has been improving in recent years (Walker et al. 2004; Carter and Rybioki 1986), the Anacostia River, which runs into the estuary, remains a seriously stressed system with high levels of PAHs, PCBs, pesticides, and heavy metals (Phelps 2004). Researchers have also observed elevated concentrations of Aeromonas spp. during the summer months in Anacostia waters relative to concentrations observed in most natural waters (Cavari 1981). The effects of the degraded condition have been far reaching on the biological communities with high mortality rates of filter feeding bivalves (Phelps 1993, 2004); high tumor incidence among resident bullhead catfish (Sakaris et al. 2005, Pinkney et al. 2004), and adverse impacts on the populations of invertebrate macrofauna (Phelps 1985). These effects may impact the microbial community as well. Microbial DNA isolated from sediment from several locations on the Anacostia River reflecting a pollution gradient of heavy metals and organics (see Velinsky et al. 1994 and Wade et al. 1994 for sites), was found to have unique signatures in different regions of the river (Bushaw-Newton, Adams, and Velinsky, unpublished data). Despite increased attention on the Anacostia's environmental degradation, improvements have been marginal (Hall et al. 2002). Benthic organisms remain rare; Asiatic clams experience extremely low survival and have not established resident populations; fish remain unsafe to eat; and over 100 million gallons of raw waste entered the river in the past two years (Washington Post 2005). While studies have concentrated on the larger, macrofauna, little attention has been paid to the microbial and the macroinvertebrate communities. Yet, the structure and function of these two communities often plays a key role in dictating the structure and function of the larger biological community as well as the chemical components of the system.

Silica and Siliceous Surfaces as Hosts for Hazardous Metals in Water

Ion exchange reaction on clay minerals and sorption by iron oxide minerals have long been regarded as the major reactions governing the fate and transport of metals in surface and ground waters, and in contaminated soils.  In addition, silica gels can also bind metals by sorption and co-precipitation reactions.  Our earlier sampling of tap water in the District of Columbia and of Potomac River water upstream of the water supply intakes (see below) suggests that silica-rich scales formed inside distribution pipes and shedding into consumed water can be a host for trace metals of health concern, such as lead (Pb) and copper (Cu).

A preliminary study of several samples of city water was performed in 2004-2005.  One sample of water was taken from a seldom-used tap in the cold water system in Maloney Hall, housing the Department of Chemistry at The Catholic University of America.  A 1-liter sample of this water was passed through a series of cellulose acetate/cellulose nitrate membrane filters (5.0, 1.2 and 0.65 microns).  The solid deposit left on each filter was dissolved in an acid mix (dilute HF + HCl) and analyzed using an ICP atomic emission spectrometer.  The filtrate which passed through the final filter (0.65 microns) was also analyzed.  The results of the elemental analysis were expressed in terms of oxide content relative to the total amount of deposit on each filter.  The results of the analysis are shown in the Table 1:

Table 1:  Precipitates and filtrates from cold water tap in Maloney Hall, CUA

The low concentration of alumina relative to silica in the particulate matter indicates that the majority of the silica is present in free form rather than in the form of clay or feldspar.  The hazardous metal (Zn, Cu, Pb, Cr, Ni) concentrations (reported here in % on an oxide basis) in all three particle size fractions are greatly elevated with respect to typical crustal rocks and soils (Shacklette et al. 1971); for example, the average Pb concentration in soils is about 20 mg/kg (0.002 %).  Indeed, the presence of the hazardous metals in particulate matter recovered from tap water can be attributed to corrosion and abrasion of pipes, joints and valves in the water supply and distribution system, as documented in the literature (Edwards and Jacobs, 1996; Viraraghavan et al., 1996; Isaac et al., 1997; Hong and Macauley, 1998; Edwards et al., 1999).
       
While some of the hazardous metal content may be present in metallic or metal oxide particles, hazardous metal species may be sorbed on, or co-precipitated with, silica.  Radium, for instance, is known to adsorb on both quartz and silica gel (Ames et al., 1983; Nirdosh et al., 1987).  Further work is necessary in order to evaluate the importance of sorption of hazardous metals on silica or their co-precipitation with silica in various aqueous environments, in particular those relevant to drinking water and environmental streams in geographical areas where widespread contamination with respect to lead and copper exists, such as the Washington, DC, area.
       
In order to compare this treated, tap water with natural waters from the Potomac River watershed upstream of the District, several river samples from the Harpers Ferry National Historical Park were similarly passed through a series of membrane filters and analyzed.  The results are shown in Tables 2 - 4.

Table 2:  Piney Run, VA (north of Loudon Heights)

Table 3:  Maryland Heights Potomac Stream, MD (across the Potomac River from Harpers Ferry)

Table 4:  Potomac River (northeast of Shenandoah River confluence)

Although the ratios of silica concentration to those of alumina and calcium oxide in the natural stream samples are lower than those in the tap water, some free silica (presumably as quartz) is probably present in the suspended sediment of the river.  For instance, this is likely to be the case in the Maryland Heights Potomac Stream of Table 3, in particular with respect to the fine particulate fraction (1.2-5.0 microns).  This free silica would therefore be available to sorb metal ions.   Thus the metal ions that are found in the particulate matter suspended in the natural water, as well as in the tap water, may be present, at least in part, in adsorbed form on silica particles.
       
Reactions at silica surfaces are complex and the presence of foreign ions in solution can enhance sorption and ion exchange on siliceous surfaces.  For example, polyvalent ions, such as Cu2+, react very slowly with siliceous surfaces in near-neutral solutions.  The process is greatly accelerated when the siliceous surface is contacted with solutions of sodium and particularly ammonium ion, prior to or simultaneously with contact of the copper solution (Patrick and Barclay, 1925; Ponomareva et al., 1975; Simmons, 1981).  Organic species attached or adsorbed on silica surfaces are also known to promote sorption of metal ions (Macedo and Barkatt, 1987a, 1987b; Chiron et al., 2003).  The concentration of metal ions affects the adsorption kinetics of metal ions, even though the adsorption equilibrium is unaffected if the concentration of metal ions is sufficiently high to produce full occupancy of the surface sites (Vithayaveroj et al., 2003).  Previous contact of siliceous surfaces with specific anions, such as sulfate, also affects adsorption properties with respect to heavy metal ions (Nirdosh et al., 1987).  

Wet-Weather Flow Characterization for the Rock Creek through Monitoring and Modeling

Principal Investigator:      Dr. Aaron Barkatt

Associate Professor
Engineering, Architecture & Aerospace Technology
University of the District of Columbia
Washington, DC 20008
Email: pbehera@udc.edu

Co-principal Investigator:  Dr. Abiose Adebayo, Ph.D.

Engineering, Architecture & Aerospace Technology
University of the District of Columbia
Washington, DC 20008
Email: aadebayo@udc.edu

Wellela Hirpassa, M.Sc.
Water Quality Extension Agent
Cooperative Extension Service
University of the District of Columbia
Email: whirpassa@udc.edu

 

In spite of massive public investments in sewage and drainage infrastructure, pollution loading from wet-weather flows continues to have significant impacts on receiving waters. Trends in urbanizations, increased quantities of urban wet-weather flows and corresponding increase in pollution loadings discharged to receiving waters demand that wet-weather flow control systems be planned and engineered to effect higher levels of water quality control. For future investments in drainage infrastructure to be cost-effective, decisions in wet-weather flow control systems planning must be made within a rigorous, comprehensive and systematic framework.

Similar to many older cities in the nation, the sewer system in the District of Columbia is comprised of both combined and separate sewer systems. It has recognized that these systems contribute significant pollution to the Anacostia and Potomac Rivers and Rock Creek through Combined Sewer Overflows (CSOs) and Storm Sewer discharges during wet-weather (i.e., rainfall and snowmelt) events. These overflows and associated pollutant loads can adversely impact the quality of the receiving waters. As per the District of Columbia water quality standards, the designated use of the Anacostia River, Potomac  River and Rock Creek is Class A or suitable for primary contact recreation. Because the water quality in the receiving waters currently does not meet these standards much of the time, the actual use of the water body is Class B or suitable for secondary contact recreation and aquatic enjoyment. As a result, the District law prohibits primary contact recreation such as swimming in each of the receiving waters (DC WASA, 2002). To address these problems, the District of Columbia Water and Sewer Authority (WASA) has developed a Long Term Control Plan (LTCP) that provides the alternative solutions and their implementation costs.

In order to support LTCP a continuous monitoring and modeling of the system is necessary not only to provide technical assessment but also to develop a cost-effective solution. In this regard, a long-term study has been proposed to characterize the Rock Creek wet-weather flows. Rock Creek is a free flowing urban stream located within a completely developed environment. The initial goal of the proposed study is to perform water resources engineering analysis and characterize the runoff quality in terms of pollution loads from CSOs and storm water discharges. The characterization will be very much helpful for the Total Maximum Daily Load (TMDL) development as well as in the development of LTCP. Furthermore the characterization will meet the objective of Mid-Atlantic Regional water quality program.