pubs.acs.org/cgi-bin/sample.cgi/esthag/asap/html/es0518631.html
Department of Civil and Environmental Engineering, Louisiana State Univer sity, Baton Rouge, Louisiana, CK Associates, Baton Rouge, Louisiana, Gor don A and Mary Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, Louisiana, EHS Technical Solutions, Baton Roug e, Louisiana, and Louisiana Water Resources Research Institute, Louisian a State University, Baton Rouge, Louisiana Received for review September 20, 2005 Revised manuscript received September 27, 2005 Accepted September 29, 2005 Abstract: Hurricane Katrina, rated as a Category 4 hurricane on the Saffir-Simpson scale, made landfall on the U S Gulf Coast near New Orleans, Louisiana on Monday, August 29, 2005. The storm brought heavy winds and rain to t he city, and several levees intended to protect New Orleans from the wat er of Lake Pontchartrain were breached. Consequently, up to 80% of the c ity was flooded with water reaching depths in excess of three meters in some locations. Research described in this paper was conducted to provid e an initial assessment of contaminants present in floodwaters shortly a fter the storm and to characterize water pumped out of the city into Lak e Pontchartrain once dewatering operations began several days after the storm. Data are presented which demonstrate that during the weeks follow ing the storm, floodwater was brackish and well-buffered with very low c oncentrations of volatile and semivolatile organic pollutants. Dissolved oxygen was depleted in surface floodwater, averaging 16 mg/L in the La keview district and 48 mg/L in the Mid-City district. Lead, arsenic, and in some cases, chrom ium, exceeded drinking water standards but with the exception of some el evated Pb concentrations generally were typical of stormwater. Data sugg est that what distinguishes Hurricane Katrina floodwater is the large vo lume and the human exposure to these pollutants that accompanied the flo od, rather than very elevated concentrations of toxic pollutants. Introduction Hurricane Katrina was a Category 4 storm on the Saffir-Simpson scale when it made landfall near New Orleans, Louisiana on Monday, August 29, 2005 . Hours after the passage of the storm, several levee breaks occurred in Orleans Parish, portions of which lie below sea level. This resulted in water levels in excess of 3 m in some portions of the city of New Orlea ns accompanied by massive damage to property and loss of life. Many resi dents and first-responders were exposed to the floodwater over the cours e of several days and serious concerns about potential pollutants in the floodwater have been expressed in various forums. These include concern over toxic chemical constituents, potentially pathogenic microorganisms , and the attendant public health implications resulting from exposure t o these waters. Potential sources of pollutants following flooding include sewage leaking from the wastewater collection system, septic tanks, and wastewater tre atment plants, gasoline leaking from submerged vehicles and fuel station s, chemicals leaching from industrial facilities, businesses, and submer ged homes, and decaying vegetation and other organic debris.
The objective of the current study was to present a snapshot of the chemi cal and microbiological characteristics of the water immediately followi ng the flood caused by Hurricane Katrina. The focus of the initial effor t was to collect as complete a dataset of chemical and microbial constit uents as possible that encompassed street-to-street variability and samp ling across the depth of the floodwater column. Samples were collected i n the main area of the city of New Orleans, the "East Bank", where prima ry human contact with the floodwaters occurred during rescue operations. Samples were also collected from the 17th Street drainage canal, before and after pumping began, to facilitate assessment of potential impacts on Lake Pontchartrain, the receiving body for floodwaters pumped from th e city of New Orleans. Floodwater samples were collected from two Orleans Parish "East Bank" locations: in the West End and Lakeview neighborhoods of the Lake view district on Saturday, Sept. Sampling locations in the Lakeview district are denoted by points numbe red 1-21 in Figure 1, and sampling locations in the Mid-City district ar e denoted by points labeled as NO-1-NO-9. The Lakeview district is bound by Lake Pontchartrain to the north and the 17th Street Canal to the wes t The Lakeview district is composed of newer residential neighborhoods and is near one of the larger canal breeches at the 17th Street Canal. I t was selected for sampling strictly based on accessibility and safety i ssues immediately after the flood. Once these analyses were completed, a second area was targeted for sampling that would provide contrast to th e Lakeview district with respect to land use, contact time with the floo dwaters, and distance from the levee breaks. The Tulane-Gravier neighbor hood in the Mid-City district was selected to provide this contrast. It is a mixed-use area that includes low-income residential, light industry , and a health-care education complex. It is located 6-8 miles from any of the levee breaks and possesses some of the lowest elevations within N ew Orleans' bowl-shaped topography. Both the Lakeview and Mid-City locat ions are located within the leveed "East Bank" of Orleans Parish. This c ontiguous urban area had the highest population of the flooded areas of the city and had the greatest number of residents exposed to the floodwa ter. Additional samples for some constituents were collected in Lake Pon tchartrain on Saturday, September 3 for comparison purposes.
Samples were obtained using a flat-bottomed boat equipped with a small ou tboard motor. Samples were collected at street intersections using the c ross-street patterns as a makeshift grid. When approaching an intersecti on targeted for sampling, the motor was turned off and the boat was allo wed to drift in, minimizing mixing of water that was collected. For the Lakeview sampling event, surface samples were collected. For the Mid-Cit y sampling event, surface and bottom samples were collected. Bottom samp les were obtained using a low-flow peristaltic pump with collection tubi ng placed on the bottom of the floodwater column at street level. These data were supplemented by dissolved oxygen profiles, fecal coliforms, an d chemical oxygen demand (COD) sampling along the 17th Street Canal (Fig ure 1 points labeled as C1-C15), the location of a major levee breach an d, after the levee repair, one of the routes of floodwater discharge int o Lake Pontchartrain. Samples collected along the length of the 17th Str eet Canal on Sept. Data presented in this paper met all quality control criteria a nd sample preservation requirements described in the referenced methods. Field Parameters (DO, pH, ORP, Conductivity, Tem perature, Turbidity, and Alkalinity). Dissolved oxygen was measured in the field by titration us ing the Winkler method. Temperature, conductivity, oxidation-reduction p otential (ORP), and pH were measured using a calibrated Myron L Ultramet er. Alkalinity was measured immediately in the field using a calibrated sulfuric acid titrant with bromocresol green as an indicator. Turbidity was measured by a calibrated HACH 2100 A turbidity meter (Hach, Loveland , CO). Organic Constituents (COD, Volatiles, and Semivolatiles). COD was measure d by the closed reflux colorimetric method using Hach 8000 reaction vial s according to the manufacturer's recommended protocol. Semivolatile org an ics were measured using EPA Method 625 by Pace Laboratories (Kansas C ity, KS). Volatile organic compounds were measured using EPA Method 624 by Pace Laboratories. In addition, separate analyses were performed to s earch for volatiles not included on the Method 624 list. For these analy ses, an EPA Method 624 technique was applied to 5-mL samples on an Agile nt 6890/5973N GC-MS operating in full-scan mode. Spectra from unknown pe aks were compared with NIST library spectra and identifications were ass igned based on comparisons between observed retention times and expected retentio...
|
http://csua.com/feed/