Environ. Sci. Technol. 2006, 40, 4571-4577
Metal Distributions in New Orleans Following Hurricanes Katrina and Rita: A Continuation Study G E O R G E P . C O B B , * ,† M I C H A E L T . A B E L , †,| THOMAS R. RAINWATER,‡ GALEN P. AUSTIN,† STEPHEN B. COX,† RONALD J. KENDALL,† ERIC J. MARSLAND,† TODD A. ANDERSON,† BLAIR D. LEFTWICH,| JOHN C. ZAK,§ AND STEVEN M. PRESLEY† Department of Environmental Toxicology, The Institute of Environmental and Human Health, Texas Tech University, P.O. Box 41163, Lubbock, Texas, 79409-1163, The Institute of Environmental and Human Health Field Station, Jeffersonian Institute, P.O. Box 764, Jefferson, Texas, 75657, Department of Biological Sciences, Biology Building, Texas Tech University, Lubbock, Texas, 79409-43131, and TraceAnalysis, Incorporated, 6701 Aberdeen Avenue, Lubbock, Texas, 79424
In late October 2005, twenty-seven metals were determined in soils and sediment layers deposited by floodwaters (flood sediments) within New Orleans, Louisiana. Samples originated from 43 sites along four transects, at an industrial canal, and near the Superdome. The sampling design encompassed flooded and nonflooded areas as well as differing economic strata within the city. Results from this effort confirmed findings of our previous study designed to quantify contaminant profiles in the aftermath of Hurricane Katrina. The expanded sampling from this most recent investigation revealed that arsenic (As) and lead (Pb) concentrations exceeded United States Environmental Protection Agency (USEPA) soil screening criteria indiscriminately throughout the city. However, As and Pb concentrations were lower along St. Charles Avenue, an area largely unaffected by hurricane related flooding. Toxicant concentrations did not exceed soil screening criteria values for lead within any flood sediments or for 32 of 37 soil samples, but arsenic concentrations in 40 of 43 samples exceeded screening criteria.
Introduction In the aftermath of Hurricane Katrina, multiple breaches occurred in the levee and canal system (1) protecting New Orleans, LA, from water in Lake Pontchartrain. As a result, suspended solids in the floodwaters were dispersed over the affected areas. Removal of floodwaters did not occur simultaneously throughout the city. Thus, some areas were flooded for extended periods, thereby allowing more time for sediment deposition and creating possible inherent * Corresponding author phone: 806-885-4567; fax: 806-885-4577; e-mail:
[email protected]. † Department of Environmental Toxicology, The Institute of Environmental and Human Health, Texas Tech University. ‡ The Institute of Environmental and Human Health Field Station, Jeffersonian Institute. § Department of Biological Sciences, Texas Tech University. | TraceAnalysis, Incorporated. 10.1021/es060041g CCC: $33.50 Published on Web 07/01/2006
2006 American Chemical Society
heterogeneity of contaminant distribution (2). Reflooding of low-lying areas also occurred following the heavy rains associated with Hurricane Rita, providing another opportunity for contaminant redistribution within the city. Initial post-Katrina studies of the New Orleans area revealed the presence of environmental contaminants in floodwater (3) and sediments (4). The first report indicated elevated aromatic hydrocarbons, lead, arsenic, and chromium concentrations in floodwater (3). This may be indicative of stormwater runoff from the New Orleans area (5) as well as resuspension of estuarine sediments (2). Between September 16 and 18, while New Orleans was still partially flooded, soil and sediment samples contained As, Pb, and Fe concentrations (4) that exceeded regulatory thresholds for human health (6). Elevated metal presence in the city was exacerbated by high bacterial counts in floodwaters (4). Metal tolerance in bacteria accelerates bacterial resistance to antibiotics (7), which could pose public health concerns. While there has been much media discussion regarding the interpretation of these data, it should be noted that USEPA guidance for assessment of contaminated sites includes tabulated data that provide human health soil screening levels (HHSSLs) and high priority bright line screening levels (HPBLSLs) for numerous toxicants (8, 9). HHSSLs represent toxicant concentrations in soil that pose hazard quotients of 1 for noncancer endpoints or 10-6 cancer risks to humans. Conversely, HPBLSLs indicate a hazard quotient ranging from 3 to 10 for noncancer endpoints or a 10-4 cancer risk. These tables list HHSSLs for As at 22.0 µg/g and 0.39 µg/g for noncancer and cancer endpoints, respectively. The HPBLSL for As is 39.0 µg/g. For Pb, the HHSSL and HPBLSL for hazard assessments are the same, 400 µg/g. The HHSSL and HPBLSL provide criteria to which chemical occurrences can be compared for rapid assessment of risks that exposure to soils may pose to human health. With progress underway to rebuild New Orleans’ infrastructure from the damage sustained during the disaster, it is essential to safeguard citizens and visitors returning to the city by determining the extent of the contamination throughout the municipality. In this way, distributions of potential exposures can be estimated so that decisions can be made regarding risks to humans or the environment. Preliminary investigation revealed toxicant concentrations in soils/sediments that suggested an exposure hazard to humans from metals (4). However, the initial sampling effort was limited, as much of the city remained flooded at the time of sampling. Thus, results of the study were insufficient to extrapolate any contaminant concentration pattern across the city. Moreover, the flooding pattern in New Orleans raised the question of whether areas experiencing extended contact with floodwaters would have more persistent and excessive concentrations of toxic metals. The Lower Ninth Ward was submerged for the longest period of time, while the Fifth through Eighth Wards were also inundated for a significant period. The goals of our current investigation were to compare toxicant occurrence in soils and sediments from September and October 2005 sampling efforts and to develop a more extensive profile of toxicant distributions within New Orleans following significant hurricane flooding. This was accomplished by establishing transects through the Sixth and Ninth Wards along with new sampling in the relatively unflooded Garden District and by resampling the original study transect (4). We have focused on metal contaminants in this paper to expedite information flow regarding contaminant distriVOL. 40, NO. 15, 2006 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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FIGURE 1. Sediments in the streets of the Lower Ninth Ward in New Orleans, LA on October 26, 2005. Panel A shows the sedimentation and panel B shows the 2.5-3 cm depth of the sediment on the sidewalk at this sampling location.
FIGURE 2. Map of arsenic concentrations determined along sampling transects through New Orleans from late October 2005. Key: red square, exceeds 22 µg/g, the noncancer soil screening levels; brown square, exceeds 10 µg/g, 25 times the cancer soil screening level; orange square, exceeds 0.39 µg/g, the cancer soil screening level; yellow square, below 0.39 µg/g. Note that sites T2-3 and T3-2 are coincident at a street intersection. (Color infrared orthophoto provided courtesy of Louisiana Oil Spill Coordinator’s Office.) butions in New Orleans in the wake of Hurricanes Katrina and Rita. Soil and flood sediments (Figure 1) were collected from four transects that encompassed all ranges of flooding and a diversity of socioeconomic regions within New Orleans (Figure 2; Table 1). This sampling design also included sites along a transect from a study conducted in the immediate aftermath of Hurricane Katrina (4). Two transects extended roughly north and south between the French Quarter and Lake Pontchartrain, and two others extended East and West. Transect 1 (T1) ran along Esplanade Ave., the boundary between the Sixth and Seventh Wards and northerly along Wisner Blvd., the boundary between the Fifth and Seventh Wards, to Lake Pontchartrain. T2 ran between the riverfront and lakefront termini of Elysian Fields Ave. (the boundary for the Seventh and Eighth Wards). T3 ran east and west along Claiborne Ave. and Robertson St., bisecting the northsouth transect (T2) and traversing the Seventh, Eighth, and Ninth Wards. T4 was taken along St. Charles Ave., through 4572
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the First, Second, and Tenth-Thirteenth Wards, a relatively nonflooded area of the city. There were also two samples taken near the industrial canal (IC) as well as two samples near the Superdome (SD). When possible, flood sediments were collected to ensure samples consisted strictly of sediment. At each sampling location, the top layer (2.5 cm) of soil or sediment was collected to minimize incorporation of pre-Katrina soil/sediment in samples. A total of 43 soil and sediment samples were collected. In addition, one grass sample was collected from site T3-8, where dried sediments covered the streets and yards to depths exceeding 2.5 cm. Each soil and sediment sample was collected using one of two stainless steel hand trowels, which were cleaned with acetone between sampling events. Samples were placed in pre-cleaned 4 oz soil jars (Eagle Picher, Phoenix, AZ) and stored on ice for 72 h or less until shipment to Texas Tech University. Once there, samples were stored in a freezer until they were split and sent to TraceAnalysis, Inc. for analysis.
TABLE 1. Locations of Sampling Sites within New Orleans that were Accessed on October 28 and 29, 2005 site ID
latitude (north)
longitude (west)
comments
T1-1 T1-2 T1-3 T1-4 T1-5 T1-6 T1-7 T1-8 T1-9 T2-1 T2-2 T2-3b T2-4 T2-5 T2-6 T2-7 T2-8 T2-9 T2-10 T2-11 T3-1 T3-2b T3-3 T3-4 T3-5 T3-6 T3-7 T3-8 T3-9 T3-10 T4-1 T4-2 T4-3 T4-4 T4-5 T4-6 T4-7 T4-8 T4-9 T4-10 ICS-A ICS SD-1 SD-2
29° 58′ 11.82′′ 29° 58′ 28.22′′ 29° 58′ 45.13′′ 29° 58′ 0.06′′ 29° 59′ 47.19′′ 30 ° 0′ 16.02′′ 30 ° 0′ 48.09′′ 30 ° 1′ 13.11′′ 30 ° 1′ 38.76′′ 29° 57′ 41.83′′ 29° 58′ 9.62′′ 29° 58′ 24.06′′ 29° 58′ 50.86′′ 29° 59′ 19.8′′ 29° 59′ 41.95′′ 30° 0′ 4.35′′ 30° 0′ 29.33′′ 30° 0′ 59.49′′ 30° 1′ 30.38′′ 30° 1′ 51.24′′ 29° 58′ 21.49′′ 29° 58′ 24.06′′ 29° 58′ 22.22′′ 29° 58′ 16.51′′ 29° 58′ 10.54′′ 29° 58′ 5.14′′ 29° 57′ 58.84′′ 29° 57′ 51.98′′ 29° 57′ 45.87′′ 29° 57′ 45.73′′ 29° 56′ 11.26′′ 29° 56′ 1.98′′ 29° 55′ 49.42′′ 29° 55′ 38.6′′ 29° 55′ 35.84′′ 29° 55′ 38.15′′ 29° 55′ 48.87′′ 29° 56′ 3.1′′ 29° 56′ 18.78′′ 29° 56′ 31.58′′ 29° 59′ 19.27′′ 29° 58′ 55.22′′ 29° 57′ 4.94′′ 29° 57′ 16.79′′
90° 4′ 9.13′′ 90° 4′ 33.08′′ 90° 4′ 56.5′′ 90° 5′ 19.11′′ 90° 5′ 10.23′′ 90° 5′ 12.65′′ 90° 5′ 7.88′′ 90° 5′ 1.54′′ 90° 5′ 3.97′′ 90° 3′ 23.17′′ 90° 3′ 23.82′′ 90° 3′ 27.03′′ 90° 3′ 27.86′′ 90° 3′ 28.21′′ 90° 3′ 31.12′′ 90° 3′ 34.56′′ 90° 3′ 34.57′′ 90° 3′ 37.21′′ 90° 3′ 42.56′′ 90° 3′ 31.16′′ 90° 3′ 55.12′′ 90° 3′ 27.03′′ 90° 2′ 56.86′′ 90° 2′ 28.81′′ 90° 2′ 2.98′′ 90° 1′ 39.2′′ 90°1′ 11.09′′ 90° 0′ 42.81′′ 90° 0′ 22.78′′ 90° 0′ 13.16′′ 90° 7′ 32.43′′ 90° 7′ 19.45′′ 90° 6′ 59.27′′ 90° 6′ 38.25′′ 90° 6′ 12.2′′ 90° 5′ 40.45′′ 90° 5′ 14.25′′ 90° 4′ 49.93′′ 90° 4′ 34.77′′ 90° 4′ 25.23′′ 90° 1′ 47.67′′ 90° 1′ 43.24′′ 90° 4′ 39.77′′ 90° 4′ 44.99′′
1621 Esplanade Ave. (E1)a Esplanade Ave. & Rocheblave St. (E2) Esplanade Ave. & Le Page St. (E3) Esplanade Ave. & Moss St. (E4) Wisner Blvd. N. of I-610 (E5) Wisner Blvd. City Park Golf Course (E6) Wisner Blvd. N. of Filmore Ave. (E7) Wisner Blvd. & Robt. E. Lee Blvd. (E8) Lakeshore Park - Lake Pontchartrain (E9) Elysian Fields Ave. & N. Peters St. Elysian Fields Ave. & St. Claude Ave. N. Claiborne Ave. & Elysian Fields Ave. Elysian Fields Ave. & N. Tonti St. Elysian Fields Ave. & Abundance St. Elysian Fields Ave. & Sere St. Elysian Fields Ave. & Pelopidas St. Elysian Fields Ave. & Mirabeau Ave. Elysian Fields Ave. & Prentiss Ave. Elysian Fields Ave. & Leon C. Simon Dr. 2222 Lakeshore Dr. St. Bernard St. & N. Claiborne Ave. N. Claiborne Ave. & Elysian Fields Ave. N. Robertson St. & Franklin Ave. SW corner of N. Robertson St. & Louisa St. N. Robertson St. & Bartholomew N. Robertson St. & Railroad Yard N. Robertson St. & Forstall N. Robertson St. & Albo N. Robertson St. & Delery N. Claiborne Ave. & Orleans Parish St. Charles Ave. & Newcomb Pl. St. Charles Ave. & Loyola University St. Charles Ave. & Nashville Ave. St. Charles Ave. & Dufossat St. St. Charles Ave. & Jena St. St. Charles Ave. & Antonine St. St. Charles Ave. & Sixth St. St. Charles Ave. & Jackson Ave. St. Charles Ave. & Terpsichore St. St. Charles Ave. & U. S. 90 France Rd. & Alvar St. Alvar St. & Pleasure St. Poydras St. & LaSalle Gravier St. & LaSalle
a Parenthetical information represents the site designation from our previous study (4). To maintain data independence, only T3-2 is used in mean computations for transects.
Soil and sediment samples were prepared by solid waste Method 3050B (10). Slight modifications to the method were made, but sample integrity was maintained. Aliquots of 0.5 g were weighed and placed into individual Nalgene digestion tubes. Each soil/sediment was then digested with 1:1 HNO3/ water and heated at 95 °C for 15 min. Digests were allowed to cool and 2 mL of water was added to each. An H2O2 solution (30% w/v; 3 mL) was added to the samples. Each digestion tube was heated until the effervescence caused by the hydrogen peroxide had subsided. Subsequently, 10 mL of concentrated HCl was placed into each sample container, and the samples were reheated at 95 °C until the solution was reduced to 5 mL. Samples were diluted to 50 mL with DI water for analyses (10). Quality control procedures described in Method 3050B were conducted during sample preparation processes. Each batch of 10 samples included a method blank, a pair of laboratory control spikes, a pair of matrix spikes, a duplicate, a post digestion spike, and a serial dilution. This ensured the integrity of the analyses (10). Inorganic analysis was performed by inductively coupled plasma with atomic emission spectroscopy (ICP-AES) using solid waste Method 6010B (11). Wavelengths prescribed by
b
Sites T2-3 and T3-2 are coincident at a single location.
this method were modified to overcome interferences from iron and other elements found in the soil and sediment. Samples were analyzed for 26 separate metal constituents (Ag, Al, As, B, Ba, Be, Cd, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, P, Pb, Sb, Se, Si, Sn, Sr, Ti, Tl, V, and Zn). Each sample was diluted appropriately so that metal concentrations would fall within the calibration curve of the instrument. No methodological contamination was detected in the samples or the instrument according to quality control data from each sample batch. An interference check was performed to establish a clean performance line for each metal constituent (11, 12). Another aliquot of soil was removed from each sample and weighed to determine moisture content, by method SM D2974-87 (13). Metal concentrations were then converted to a dry weight basis. Data were reported through a laboratory information management system (Versa LIMS: TraceAnalysis, Inc. Lubbock, TX). Analyte concentration data were normalized by log transformation prior to analysis. Statistical analyses included analysis of variance (ANOVA) and Tukey’s post-hoc tests with an R of 0.05 to determine differences among transects. All analyses were performed using R statistical package (14). VOL. 40, NO. 15, 2006 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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Results
TABLE 2. Metal Concentrations in Individual Samples Collected October 28 and 29, 2005 from New Orleans, LA sampling site
sample type
T1-1 T1-2 T1-3 T1-4 T1-5 T1-6 T1-7 T1-8 T1-9
soil soil soil soil soil soil soil soil soil
Twenty-four of the twenty-seven metal constituents tested in the soil and sediment samples collected within New Orleans did not exceed concentrations listed by USEPA in HHSSL or HPBLSL criteria. The exceptions were As, Pb, and Fe (Table 2).
metal concentration (µg/g) maximum arsenic iron lead flood depth (m) 3.82a 5.2a 1.69a 2.72a 6.25a 7.7a 1.22a 3.32a 1.86a
9760 12100 8010 6860 15500 8090 1870 10200 2400
177 560c 300 128 177 29.1 18.6 106 9.84
T2-1 T2-2 T2-3 T2-4 T2-5 T2-6 T2-7 T2-8 T2-9 T2-10 T2-11
soil 21.7a 13300 184 soil 6.17a 17400 1460c d soil NA NA NA soil 21.7a 13900 335 a soil 17.6 24600a 117 soil
