haw river sediment quality assessment july 2011
TRANSCRIPT
i
U.S. Fish and Wildlife Service U.S. Geological Survey
Ecological Services Columbia Environmental Research Center
Raleigh, North Carolina Columbia, Missouri
Haw River Sediment Quality Assessment
July 2011
ii
Preface
The U.S. Fish and Wildlife Service coordinated an assessment of the chemical contaminants in,
and toxicity of, sediments within the impounded reaches upstream of dams on the Haw River,
North Carolina. The work was coordinated by Tom Augspurger (Ecologist / Environmental
Contaminant Specialist) and Sara Ward (Ecologist / Environmental Contaminant Specialist) in
the U.S. Fish and Wildlife Service’s Raleigh Field Office and was funded by the U.S. Fish and
Wildlife Service’s Division of Environmental Quality (study identifiers 4F41 and 200840001.1).
Toxicity tests were performed by the U.S. Geological Survey’s Columbia Environmental
Research Center (CERC) under the direction of Chris Ingersoll through an intra-agency
agreement with the U.S. Fish and Wildlife Service. Other CERC scientists primarily responsible
for the toxicity testing component of the project were Nile Kemble and James Kunz. Adam
Riggsbee of RiverBank Ecosystems (formerly with Restoration Systems, LLC) assisted with
sample site selection during a field reconnaissance. Katherine Irvine with the North Carolina
Wildlife Resources Commission assisted with sample collection. Analytical chemistry was
performed by Environmental Conservation Laboratories, Inc. This final report follows a 2009
summary of methods and results.
Additional questions, comments, and suggestions related to this report are encouraged. Inquires
can be directed to the U.S. Fish and Wildlife Service at the following address:
Tom Augspurger
U.S. Fish and Wildlife Service
P.O. Box 33726
Raleigh, North Carolina 27636-3726
Suggested citation: U.S. Fish and Wildlife Service. 2011. Haw River Sediment Quality
Assessment. U.S. Fish and Wildlife Service, Ecological Services, Raleigh, NC.
Cover: Saxapahaw Dam, Haw River, North Carolina
Keywords: Haw River, North Carolina, sediments, 4F41, 200840001.1, NC-2, NC-4, NC-6
iii
Haw River Sediment Quality Assessment
Abstract
This report documents an evaluation of chemical contaminants in, and toxicity of, sediments
collected from impoundments created by dams on the Haw River in Alamance and Chatham
Counties, central North Carolina. Eighteen whole-sediment samples from within the impounded
reaches of Swepsonville Dam, Saxapahaw Dam, Bynum Dam, and B. Everett Jordan Dam were
collected in June 2008. All samples were analyzed for elemental contaminants and polycyclic
aromatic hydrocarbons. All samples were also assessed with a battery of toxicity tests.
Elemental contaminant concentrations in whole-sediments were below those of toxicological
significance. One or more sediment PAHs with freshwater sediment threshold effects screening
values exceeded the screening values at 17 of the 18 sites, but no samples exceeded the probable
effects concentrations. Survival of Hyallela azteca (freshwater amphipod) exposed to sediments
from one of five sites in the Bynum Dam impounded reach was 80% and statistically lower than
controls in 28-d toxicity tests; amphipod growth was not affected at this or any other site. Whole-
sediments had no significant effect on survival or growth in 10-d tests with Chironomus dilutus
(freshwater midge) at any of the 18 sites. Results indicate the contaminants associated with the
whole-sediment samples were not chronically toxic to amphipods or midge. In 2-d sediment
elutriate (water-extractable fraction) tests with Ceriodaphnia dubia (freshwater cladoceran),
statistically-significant reductions in survival occurred in four of the 18 exposures (two from the
five samples taken from within the Bynum Dam impounded reach, one from the flooded portion
of Big Alamance Creek, and one in the headwaters of Jordan Lake). Chromium in pore water at
one of five sites in the Saxapahaw Dam impoundment was 119 μg/L; the State standard for
chromium is 50 μg/L. Copper, lead, and zinc in the elutriate and pore water samples exceeded
State standards infrequently but most commonly in sediments from the Saxapahaw Dam
impoundment. This is an indication that aggressive re-suspension of sediments like those tested
could temporarily impair surface water quality. These data and surveys of sediment physical
characteristics, volume, and likelihood of movement can be used together to infer the impacts the
different types of sediments disturbing activities on short-term water column chemistry. In
particular, data regarding the modeled or measured sediment re-suspension caused by specific
sediment disturbing activities (e.g., dredging, dam alterations, dam removal, etc.) will help put
the elutriate test results in context for a range of sediment management practices.
iv
CONTENTS
PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii
ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
RESULTS / DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
MANAGEMENT RECOMMENDATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
v
TABLES Page
1. Haw River sediment sampling location data and the date and time of collection 3
2. Total organic carbon, grain size and moisture measured in whole-sediment samples 14
collected from the Haw River
3. Elemental contaminants in whole-sediment samples collected from the Haw 15
River. For each element, results are compared to threshold-effects concentration
guidelines of MacDonald et al. (2000)
4. Polycyclic aromatic hydrocarbons measured in whole-sediment samples collected 16
from the Haw River. For each compound, results are compared to threshold-effects
concentrations of MacDonald et al. (2000)
5. Response of Hyalella azteca in 28-d whole-sediment exposures, Chironomus dilutus
in 10-d whole-sediment exposures, and Ceriodaphnia dubia in 2-d elutriate exposures
prepared from sediment samples collected from the Haw River 17
6. Water quality characteristics in 2-d elutriate exposures with Ceriodaphnia dubia
prepared from Haw River sediment samples and a control sediment 18
7. Elemental contaminant concentrations of 2-d elutriate exposures with Ceriodaphnia
dubia prepared from Haw River sediment samples and a control sediment 19
8. Water quality characteristics of pore water isolated from Haw River whole-
sediment samples 20
9. Elemental contaminant concentrations of pore water isolated from Haw River
whole-sediment samples 21
10. Mean water quality characteristics of overlying water in whole-sediment toxicity
tests with Hyalella azteca and Haw River sediments 22
11. Mean water quality characteristics of overlying water in whole-sediment toxicity
tests with Chironomus dilutus and Haw River sediments 23
12. Haw River sediment elutriate and pore water exceedences of North Carolina water
quality standards or action levels for elemental contaminants 24
vi
FIGURES Page
1. Vicinity map for Haw River dam sediment sampling sites 4
2. Haw River sediment sampling sites upstream of Swepsonville Dam 5
3. Haw River sediment sampling sites upstream of Saxapahaw Dam 6
4. Haw River sediment sampling sites upstream of Bynum Dam 7
5. Haw River sediment sampling sites downstream of Bynum Dam 8
1
Haw River Sediment Quality Assessment
Introduction
This report documents an evaluation of chemical contaminants in, and toxicity of, sediments
collected from impoundments created by dams on the Haw River, in central North Carolina. The
Haw River originates in the Northern Inner Piedmont ecoregion in Guilford County and drains
1,526 square miles (NCDWQ 1999) over its 110 miles before entering the Cape Fear River. The
Haw River has been dammed many times to provide power for mills, irrigation, and drinking
water. Those societal benefits can have ecological costs; impoundments were one of the three
most frequently cited stressors as limiting factors for survival and recovery of freshwater fauna
in a survey of experts for fishes, amphibians, mussels, crayfishes, and insects (Richter et al.
1997). Neves et al. (1997) and Watters (2000) reviewed the specific effects of impoundments on
freshwater mollusks, noting flow changes, population fragmentation, water quality problems and
sediment issues. Dams also alter nutrient dynamics of riverine systems (Freeman et al 2003) and
can degrade water quality within the impounded reach and downstream (Arnwine et al. 2006).
Dam removals can be conducted with high environmental gains and low impacts if structural,
operational, and seasonal controls to manage sediment transport are applied (Riggsbee 2006).
Removal of dams has re-established important anadromous fish runs in North Carolina and has
restored habitat and improved water quality for a variety of other lotic species. Experience with
the regulatory aspects of dam removal has evidenced concern over mobilization of sediments
accumulated behind dams upon their removal. Sediments can accumulate contaminants, and at
high concentrations those contaminants can be an in-place concern as well as a concern upon
downstream mobilization. Resolving these issues is not easy; there is no consistent approach for
evaluating sediments at dam removal sites, and dam owners are reluctant to conduct expensive
testing without a certain regulatory framework. Also, the lack of a specific regulatory
framework hampers efforts to manage analytical costs.
The U.S. Fish and Wildlife Service (Service) has worked with many partners to evaluate the
significance of sediment contamination at dam sites (Augspurger and Cantrell 2004, Augspurger
et al. 2007). Objective sediment characterizations inform sediment management planning, one
of the essential components of a dam removal. In 2008, we initiated this study to provide an
assessment of sediment contamination at three dams on the Haw River in Alamance and
Chatham Counties that have been identified for potential removal by conservation groups and
agencies: Swepsonville Dam, Saxapahaw Dam, and Bynum Dam. The Service and partners’
objectives of the effort were to:
1) generate current data on the chemical and physical quality of the sediments behind the
dams for comparison to sediment toxicological screening values; and,
2) assess the toxicity of whole sediments and sediment elutriates prepared from these
whole-sediment samples to sensitive aquatic organisms.
The following summary presents the sediment sampling and testing methods, results, and an
interpretation of the findings.
2
Methods
Sample sites
Factors considered in determining the number and location of samples included the location of
identified potential sources of concern and areas of sediment accumulation. Physical factors
considered included the area and depth of potentially affected sediments behind the dams,
distribution of sediments, and the length and breadth of the impounded reaches.
During reconnaissance of the river, a hydrogeologist with Restoration Systems, LLC
qualitatively surveyed the patterns and relative magnitudes of sediment deposition. Field
surveys were conducted in a small boat with a calibrated fathometer (or “depth finder”) to gage
the overall pattern of deposition by locating depositional features. Once sediment accumulations
were located, a graduated stadia rod with a metal tip was used to measure depth of refusal and to
qualitatively assess sediment composition (i.e., sand, silt, clay). Sediment accumulations with
fine grain composition were sampled using a petite Ponar dredge for verification (Restoration
Systems, LLC, 2008). Corresponding waypoints were recorded using a mapping grade GPS unit
so they could be re-located for sampling.
Sand and gravel, while the most commonly encountered sediment, have little potential for
contaminant accumulation. Areas of fine-grained sediment accumulation were targeted for
sample collection because they have the greatest potential to accumulate contaminants.
Eighteen samples were collected by a Service Ecologist / Environmental Contaminants Specialist
with e assistance of a technician with the North Carolina Wildlife Resources Commission.
Samples were collected between June 25 and 28, 2008. Table 1 lists the collection locations,
collection date, time, and specific coordinates. Figures 1 through 5 depict collection locations.
Sediment sample collection and storage
Samples were collected, transported, stored, and shipped for analyses under chain of custody.
A stainless-steel petit Ponar dredge was used to collect the top 5 to 10 cm of sediment; multiple
grabs were collected and composited to form one sample at each site. The composite of the grab
samples was homogenized by stirring with a stainless-steel spoon in a stainless-steel bucket.
Debris (e.g., sticks, leaves, rocks bigger than about 0.5 cm3) were physically removed during
homogenization. Collection equipment was thoroughly cleaned (ambient water rinse, detergent
and water scrub, distilled / demineralized water rinse, 10% nitric acid rinse, another distilled /
demineralized water rinse, acetone rinse, and a final rinse with distilled / demineralized water)
before sampling at each site.
Aliquants of the homogenate were split in into chemically cleaned glass jars (provided by the
analytical laboratory) with Teflon®-lined lids for chemical analyses with about 8 L of the same
sediment homogenate from each site placed in two high-density polyethylene jars (EP Scientific
Products, Miami, OK) for toxicity testing. Samples were stored in a cooler on ice (about 4oC) in
the field. Upon reaching the Service lab in Raleigh each evening, samples were stored
refrigerated (about 4oC).
3
Table 1. Haw River sediment sampling location data and the date and time of collection.
Sample ID River
Mile
Description and GPS Coordinates
H 1
14.2
Upstream of Bynum Dam, N 35.77778˚, W -79.14906˚ (06-25-08; 09:45 am)
H 2 14.3 Upstream of Bynum Dam, N 35.77822˚, W -79.15084˚ (06-25-08; 10:05 am)
H 3 14.2 Upstream of Bynum Dam, N 35.77708˚, W -79.15064˚ (06-25-08; 12:25 pm)
H 4 14.1
Upstream of Bynum Dam, N 35.77648˚, W -79.14922˚ (06-25-08; 12:42 pm)
H 5 14.1 Upstream of Bynum Dam, tip of island just upstream of dam,
N 35.77613˚, W -79.14842˚ (06-25-08; 2:55 pm)
H 6 36.9 Upstream of Swepsonville Dam, N 36.01054˚, W -79.36382˚
(06-26-08; 5:40 pm)
H 7 37.2 Upstream of Swepsonville Dam, right bank just downstream from Alamance
Creek, N 36.01493˚, W -79.36555˚ (06-26-08; 5:55 pm)
H 8 33.1 Upstream of Saxapahaw Dam, N 35.96228˚, W -79.33485˚ (06-27-08; 8:45 am)
H 9 32.8 Upstream of Saxapahaw Dam, N 35.95820˚, W -79.33426˚ (06-27-08; 9:00 am)
H 10 32.2 Upstream of Saxapahaw Dam, N 35.94973˚, W -79.32906˚ (06-27-08; 10:35 am)
H 11 32.1 Upstream of Saxapahaw Dam, N 35.94892˚, W -79.32762˚ (06-27-08; 10:50 am)
H 12 32.0 Upstream of Saxapahaw Dam, N 35.94831˚, W -79.32717˚ (06-27-08; 12:25 pm)
H13 36.7 Upstream of Swepsonville Dam, just upstream of the mouth of the small
divergence leading to the powerhouse, N 36.00849˚, W -79.36210˚
(06-27-08; 2:15 pm)
H 14
H15
H16
H 17
H18
36.8
37.4
37.4
8.5
7.9
Upstream of Swepsonville Dam, approximately 50’ upstream of H13,
N 36.00872˚, W -79.36225˚ (06-27-08; 2:30 pm)
Upstream of Swepsonville Dam, in flooded portion of Big Alamance Creek,
N 36.01741˚, W -79.37690˚ (06-27-08; 4:00 pm)
Upstream of Swepsonville Dam, in flooded portion of Big Alamance Creek,
N 36.01797˚, W -79.37064˚ (06-27-08; 4:40 pm)
Downstream of Bynum Dam, in headwaters of Jordan Lake, at tip of
depositional island, N 35.71328˚, W -79.09017˚ (06-28-08; 6:15 pm)
Downstream of Bynum Dam, in headwaters of Jordan Lake,
N 35.70527˚, W -79.08618˚ (06-28-08; 5:10 pm)
4
Figure 1. Vicinity map for Haw River impoundment sediment sampling sites. Samples sites
associated with each impounded reach are enlarged on subsequent maps.
1
Figure 2. Haw River sediment sampling sites upstream of Swepsonville Dam. 5
1
Figure 3. Haw River sediment sampling sites upstream of Saxapahaw Dam
6
2
Figure 4. Haw River sediment sampling sites upstream of Bynum Dam
7
8
Sediment chemical and physical analyses
Sediment samples were delivered to Environmental Conservation Laboratories, Inc. (ENCO) in
Cary, NC on June 26 and 30, 2008. ENCO has the North Carolina Laboratory Certification for
the requested analyses. Elemental contaminants and PAHs include many common pollutants
and were targeted for analyses in all samples. Additionally, these compounds have consensus-
based freshwater effects sediment quality guidelines (MacDonald et al. 2000, USEPA 2000b)
with which to evaluate the results.
Figure 5. Haw River sediment sampling sites downstream of Bynum Dam, in headwaters of Jordan
Lake.
8
9
Sediment samples were analyzed for Al, As, Cd, Cr, Cu, Fe, Pb, Mn, Ni, and Zn by USEPA
method 6010B (inductively coupled plasma-atomic emission spectrometry, or ICP-AES).
Analyses of mercury in sediment samples were by USEPA method 7471A (cold-vapor
atomic absorption spectrophotometry). ENCO analyzed sediments for PAHs, including 1-
methylnaphthalene, 2-methylnaphthalene, acenaphthene, acenaphthylene, anthracene,
benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene,
benzo(k)fluoranthene, chrysene, dibenzo(a,h)anthracene, fluoranthene, fluorine,
indeno(1,2,3-cd)pyrene, naphthalene, phenanthrene and pyrene, by USEPA method 8270C
(gas chromatography / mass spectrometry, or GC/MS).
Pore-water and elutriate samples were prepared from sediments by U.S. Geological Survey
Columbia Environmental Research Center (CERC), Columbia, MO (preparations described
below). These were also analyzed for elemental contaminants by ENCO. Elements in the
analyses included Al, As, Cd, Cr, Cu, Fe, Pb, Mn, Ni, and Zn by USEPA method 200.8
(Trace Elements by ICP/Mass Spectrometry). This method was also used to measure Mg and
Ca which provided the measures of hardness for these samples (by the calculation method in
Standard Methods SM 2340B).
Physical characterization of whole sediments included percentage water, particle size and
total organic carbon (TOC). Particle size analysis was conducted at CERC by sieve series
following methods described in Foth et al. (1982), Gee and Bauder (1986), and Kemble et al.
(1994). The TOC analyses were by the Walkley Black method (Schumacher 2002) and were
conducted by Test America of Tampa, FL (under subcontract to ENCO).
All analyses were accompanied by batch-specific quality control / quality assurance samples
(blanks, spikes, and duplicates). Review of quality assurance data indicates acceptable
precision and accuracy for all analyses. There was poor repeatability in spiked /duplicate
sample recoveries for total organic carbon, Al, Fe and Mn in sediment, but this was the result
of low spike level relative to high concentration of these constituents in sediment. Results of
duplicate sample analyses were within specifications. Some laboratory blank samples
contained low levels of As and Zn, but blank concentrations were < 0.1 mg/kg dry weight,
far less than the concentrations of these analytes in sediments and therefore of no concern in
data interpretation.
Threshold effects concentrations (TECs) and probable effects concentrations (PECs) were
used to assess the significance of sediment chemistry results. The TECs are concentrations
of contaminants in sediment below which adverse effects to sensitive aquatic organisms are
not expected to occur, and the PECs are effect-based sediment quality guidelines established
as concentrations of contaminants in sediment above which adverse effects are expected to
frequently occur in field-collected sediments (MacDonald et al. 2000).
Sediment toxicity tests
Samples were sent to the CERC by overnight delivery on June 30, 2008. Toxicity tests
included 28-d whole-sediment exposures of Hyallela azteca (freshwater amphipod)
10
evaluating effects on growth and survival, 10-d whole-sediment exposures of Chironomus
dilutus (freshwater midge) evaluating effects on growth and survival (USEPA 2000a, ASTM
2007), and 2-d sediment elutriate (water-extractable fraction of the sediment) exposures of
Ceriodaphnia dubia (freshwater cladoceran) evaluating effects on survival (USEPA 1993a).
This battery of toxicity tests was selected to help evaluate the toxicity of sediments, both in-
place and upon re-suspension.
Test organism culture - Amphipods were mass cultured at 23oC with a luminance of about
800 lux using 80-L glass aquaria containing 50 L of well water (hardness 283 mg/L as
CaCO3, alkalinity 255 mg/L as CaCO3, pH 7.8; Ingersoll et al. 2002). Amphipods used to
start the tests were obtained by collecting amphipods that passed through a #35 U.S. Standard
size (500-µm opening) and were collected on a #40 (425-um opening) sieve placed under
water. Amphipods were held in 3 L of water with gentle aeration and with a small amount of
Tetramin® and a maple leaf for 24 hours before the start of the test.
Midge were mass cultured under static conditions in 5.7-L polyethylene cylindrical chambers
containing about 3 L of water and 25 ml of silica sand as a substrate at a temperature of 25oC
and a light intensity of about 800 lux. Second instar midge (10-d old) to start the tests were
obtained by isolating <24 h old midge larvae ten days before starting the toxicity test.
Cladocerans where cultured under static conditions in 30-ml disposable clear plastic cups
each containing 15 ml of well water and one adult at a temperature of 25oC and a light
intensity of about 200 lux (USEPA 1993a). Cladocerans in each cup were fed 0.1 ml/d Yeast-
Cerophyll-trout chow (YCT; 1.7 to 1.9 g/L) and 0.1 ml/d unicellular green algae (3 x 107
cells of Selenastrum capricornutum). Neonates (<24 hours) to start the tests were obtained
from adults that produce eight or more young in their third brood or subsequent broods.
Whole-sediment toxicity tests - Whole-sediment toxicity tests with H. azteca were conducted
for 28 d and with C. dilutus were conducted for 10 d in accordance with methods described
in ASTM (2007) and USEPA (2000a) starting within 3 weeks of sediment collection.
Endpoints measured in the amphipod exposures included survival and length on Day 28.
Endpoints measured in the midge exposures included survival and growth (ash-free dry
weight) on Day 10. Test sediments were homogenized in a stainless-steel bowl using a
plastic spoon and added to exposure beakers 1 d before test organisms were added (Day -1).
Sub-samples of sediment were then collected for physical characterizations and for isolating
pore water. Amphipods and midge were exposed to 100 ml of sediment with 175 ml of
overlying water in 300-ml beakers with four replicates/treatment. The photoperiod was 16 h
light: 8 h dark at a light intensity of about 200 lux at the surface of the exposure beakers and
the temperature was 23oC. Each beaker received 2-volume additions/d of overlying water
starting on Day -1 (Ingersoll et al. 2002). Overlying water was prepared by diluting well
water with deionized water to a hardness of 100 mg/L as CaCO3, alkalinity of 85 mg/L as
CaCO3, and pH about 7.8. The water delivery system cycled every 4 h with each cycle
delivering 125 ml of water to each beaker. Tests were started on Day 0 by placing 10
amphipods or 10 midge into each beaker using an eyedropper. Amphipods in each beaker
were fed 1.0 ml of YCT (1.7 to 1.9 g/L) in a water suspension daily (USEPA 2000a, ASTM
11
2007). Midge in each beaker were fed 1.5 ml of Zeigler prime tropical flake fish food (red)
(Zeigler Bros, Inc., Gardens, PA) (6.0 mg of dry solids) in a water suspension daily (USEPA
2000a, ASTM 2007). Beakers were observed daily for the presence of animals, signs of
animal activity (i.e., burrowing), and to monitor test conditions (mainly water clarity).
Midge were isolated from each beaker on Day 10 of the exposure and amphipods were
isolated from each beaker on Day 28 of the exposure by pouring off most of the overlying
water, gently swirling the remaining overlying water and upper layer of sediment, and
washing the sediment through a No. 50 (300-µm opening) U.S. Standard stainless-steel sieve.
The materials that were retained on the sieve were washed into a glass pan and the surviving
midge and amphipods were removed. This process was repeated with the remainder of the
sediment in a beaker if all 10 of the amphipods or midge were not recovered from the upper
layer of the sediment. Amphipods from each sediment were counted and preserved in 8%
sugar formalin for subsequent length measurements (Ingersoll et al. 2002). Length of
amphipods was measured along the dorsal surface from the base of the first antenna to the tip
of the third uropod along the curve of the dorsal surface. Amphipod length measurements
were made using an EPIX imaging system (PIXCI® SV4 imaging board and XCAP
software; EPIX Inc., Buffalo Grove, IL) connected to a computer and a microscope (Ingersoll
et al. 2002). Midge from each sediment were counted and dried at 100oC in a drying oven
for subsequent ash-free dry weight measurements (ASTM 2007). Ash-free dry weight was
obtained by recording the weights after drying, transferring to an ashing oven and ashing at
500oC. Ash-free dry weights were determined by subtracting the ashed weight from the dry
weight.
About 50 ml of pore water was isolated from sediment samples by centrifugation at 5200
rpm (7000 x G) for 15 min at 4oC (Kemble et al. 1994). Immediately after pore water was
isolated, dissolved oxygen, pH, alkalinity, temperature, conductivity, total ammonia, and
hardness were measured using methods outlined in Kemble et al. (1994).
In the amphipod test, conductivity, pH, alkalinity, hardness, dissolved oxygen, and total
ammonia were measured in overlying test water on Day 0 (the day amphipods were added to
the exposure beakers) and Day 28 of the exposure. Conductivity and dissolved oxygen, in
overlying water were also measured weekly. Temperature in the water baths containing the
exposure beakers was recorded daily.
In the midge test, conductivity, pH, alkalinity, hardness, dissolved oxygen, and total
ammonia were measured in overlying test water on Day 0 (the day midge were added to the
exposure beakers) and Day 10 of the exposure. Conductivity and dissolved oxygen in
overlying water were also measured weekly. Temperature in the water baths holding the
exposure beakers was monitored daily.
Elutriate toxicity tests - Toxicity tests with C. dubia were conducted for 2 d in accordance
with methods outlined in USEPA (1993a) starting within 5 weeks of sediment collection.
Elutriate samples were prepared by mixing one part sediment with four parts water (prepared
by diluting well water, the characteristics of which are described at page 9 above under Test
organism culture, with deionized water to a hardness of 100 mg/L as CaCO3, alkalinity of 85
12
mg/L as CaCO3, and pH about 7.8). Elutriate samples were prepared following procedures
outlined in USEPA (1993a). About 50 ml of sediment was placed into two 250-ml high-
density polypropylene centrifuge tubes and topped off with 200 ml of water. The tubes were
sealed and tumbled on a rolling mill for 30 min. The tubes were then be centrifuged for 15
min at 5200 rpm (7000 x G). The water was then decanted through a US Standard #50
stainless steel sieve (300-µm opening) into a 500-ml beaker. A sub-sample of the elutriate
samples was collected for water quality characterization, with the remaining sample used in
toxicity tests.
The cladoceran test was started on Day 0 with <24-h old C. dubia. A total of 10 cladocerans
were exposed to each elutriate sample and were exposed individually in 30-ml disposable
clear plastic cups containing 15 ml of 100% elutriate test solution. Trays holding the plastic
cups were covered with plastic sheets to prevent evaporation. Cladocerans were maintained
in a water bath at 25±1º C on a 16 h light: 8 h darkness photoperiod at a light intensity of
about 200 lux. Cladocerans were not fed during the exposures. On Day 2, survival of the
cladocerans was determined by pouring all the test water into a petri dish and using a light
table to facilitate counting the neonates. Two of the elutriate samples that were found to be
toxic to C. dubia (H16 and H17) were re-tested in a dilution series. The two samples were
prepared by the same procedures outlined above and a 50 % dilution series (elutriate sample
was prepared with the 100 mg/L hardness water, testing 100, 50, 25, 12.5, 6.25% elutriate)
and a dilution water control.
Conductivity, pH, alkalinity, hardness, dissolved oxygen, and total ammonia were measured
in elutriate test water on Day 0 (the day cladocerans were added to the exposure beakers).
Temperature in the water baths containing the exposure beakers was recorded daily.
Statistical analyses
Statistical analyses for the amphipod exposures were conducted using one-way analysis of
variance (ANOVA) at p = 0.05 for all endpoints except length which was analyzed using a
one-way nested ANOVA at p = 0.05 (amphipods nested within a beaker; Snedecor and
Cochran 1982). Before statistical analyses were performed, all data were tested for
normality. Variance among treatment means for both endpoints was heterogeneous,
therefore, a rank analysis of variance was performed and mean differences were determined
using a t-test on ranked means (at p = 0.05). A sample was designated as toxic when mean
survival or growth was significantly reduced relative to the control sediment. Statistical
analyses on toxicity tests were performed with Statistical Analysis System programs (SAS
2001).
13
Results and Discussion
Whole-sediment analytical chemistry
Total organic carbon in the samples averaged 2.5% and the average percent fines (sum of silt and
clay fraction) was 58% indicating depositional areas were located for the assessment (Table 2).
There are no North Carolina or federal sediment quality criteria, but Tables 3 and 4 compare the
elemental contaminants and PAHs in whole sediment to the TECs and PECs of McDonald et al.
(2000). Florida and Wisconsin recommend TECs and PECs for use as guidance in their
programs, including evaluation of dredged material and risk assessment of contaminated sites
(MacDonald et al. 2003). While no regulatory implications are inferred in our use of the TECs
and PECs, sediment quality guidelines like these have been found to offer good utility in site
assessment by various government and non-government organizations (Wenning et al. 2005).
For elemental contaminants, only chromium at site H8 (62.6 mg/kg dry weight) exceeded the
chromium threshold-effects concentration guidelines (43.4 mg/kg) of MacDonald et al. (2000).
All other metals were less than their corresponding TECs; because sample results less than these
values are not expected to produce adverse effects to sensitive aquatic organisms, they are
therefore considered toxicologically insignificant.
In the PAH analyses (Table 4), 1-methylnaphthalene (<4 ug/kg), 2-methylnaphthalene (<3
ug/kg), acenaphthene (<3 ug/kg), acenaphthylene (<3 ug/kg), fluorine (<3 ug/kg), and
naphthalene (<3 ug/kg) were less than corresponding detection limits in all samples. Anthracene
was measured above a 4 ug/kg detection limit in only one sample, H5 which contained 110
ug/kg. One or more sediment PAHs with freshwater sediment TECs were in excess of TECs at
every sampling station except H2. No samples exceeded the PECs. MacDonald et al. (2000)
and USEPA (2000b) concluded that infrequent exceedences of TECs is not associated with
sediment toxicity; however, exceedences of PECs (by frequency or by magnitude) is frequently
associated with sediment toxicity.
Toxicity tests
Control survival of amphipods, H. azteca, was 100% and met the test acceptability requirement
of 80% survival recommended in USEPA (2000a) and ASTM (2007). Amphipod survival in the
reference sediment was 93%. Control survival of the midge, C. dilutus was 80% and also met
the test acceptability requirement of 70% survival recommended in USEPA (2000a) and ASTM
(2007). Midge survival in the reference sediment was 96%. Survival of amphipods exposed to
sediments from site H2 was 80% (Table 5) and statistically lower than controls in 28-d toxicity
tests; amphipod growth was not affected at this or any other site. Whole sediments had no
significant effect on survival or growth in 10-d tests with midges (Table 5). Results indicate the
contaminants associated with the whole-sediment samples were not chronically toxic to
amphipods or midge. In 2-d sediment elutriate (water-extractable fraction) tests with C. dubia,
statistically-significant reductions in survival occurred in four (H1, 2, 16 and 17) of the 18
exposures (Table 5). Tables 6 through 11 summarize the chemistry of elutriates and overlying
water in the whole-sediment toxicity tests.
14
Table 2. Total organic carbon, grain size and moisture measured in whole-sediment samples
collected from the Haw River.
1TA = Test America, Tampa, FL
2CERC = USGS Columbia Environmental Research Center, Columbia, MO
3ENCO = Environmental Conservation Laboratories, Inc., Cary, NC
River
Mile
Sample
ID
Total
Organic
Carbon
(%) Sand (%) Clay (%) Silt (%) Moisture (%)
TA
1 CERC
2 CERC CERC ENCO
3
Sw
epso
nvil
le
37.4 H15 1.6 55 22 23 37.5
37.4 H16 2.0 39 20 40 44.7
37.2 H7 1.9 43 18 38 45.5
36.9 H6 1.8 52 22 26 44.2
36.8 H14 2.5 43 20 37 51.8
36.7 H13 1.6 60 19 21 44.0
Sax
apah
aw 33.1 H8 2.6 28 25 47 52.1
32.8 H9 2.4 34 21 45 41.8
32.2 H10 2.6 28 22 50 57.9
32.1 H11 1.4 54 17 28 37.7
32 H12 1.8 45 21 34 44.0
Bynum
14.3 H2 2.6 75 18 7 48.7
14.2 H1 4.2 25 22 53 64.1
14.2 H3 2.8 47 20 33 56.4
14.1 H4 2.0 54 19 27 48.2
14.1 H5 2.7 41 20 39 53.6
JL 8.5 H17 5.1 23 24 53 66.4
7.9 H18 3.1 14 21 65 59.2
8
Table 3. Elemental contaminants in whole-sediment samples collected from the Haw River (mg/kg dry weight, or parts per million). Only chromium
at site H8 (in bold) exceeded threshold-effects concentration (TEC) guidelines of MacDonald et al. (2000); sample results less than these values are
not expected to produce adverse effects to sensitive aquatic organisms. No samples exceeded probable effects concentrations (PECs) – values above
which adverse effects to sediment dwelling organisms may be expected. D = data reported from a dilution. B = zinc was detected in the laboratory
blank, but at concentrations less than 0.1 mg/kg.
River Mile Sample ID Al As Cd Cr Cu Fe Pb Mn Hg Ni Zn
Sw
epso
nvil
le
37.4 H15 8950 <0.2 <0.03 20.7 11.1 20100 D 9.92 621 0.03 7.07 35.2 B
37.4 H16 12000 <0.2 <0.03 22.0 16.9 23700 D 10.8 586 0.05 9.20 60.0 B
37.2 H7 11200 <0.2 <0.03 41.5 18.1 21300 D 14.1 645 0.06 8.94 71.6 B
36.9 H6 11100 <0.2 <0.03 26.0 15.6 21600 D 12.2 606 0.04 8.81 64.5 B
36.8 H14 10600 <0.2 <0.03 29.8 19.5 17500 16.8 743 0.07 9.81 106 B
36.7 H13 6990 <0.2 <0.03 21.2 11.2 12200 10.2 756 0.05 6.64 66.2 B
Sax
apah
aw
33.1 H8 12000 <0.2 <0.03 62.6 21.4 19300 17.1 656 0.11 9.60 99.3 B
32.8 H9 10900 <0.2 <0.03 40.8 16.2 19500 D 12.8 531 0.09 8.38 73.7 B
32.2 H10 16500 <0.2 <0.03 40.1 25.0 29400 D 19.3 774 0.09 12.7 120 B
32.1 H11 6340 <0.2 <0.03 20.5 9.41 11900 8.05 313 0.04 5.64 56.5 B
32.0 H12 8600 <0.2 <0.03 24.3 13.1 15300 10.4 423 0.06 8.51 73.4 B
Bynum
14.3 H2 8590 <0.2 <0.03 42.0 12.3 13800 10.7 484 0.09 5.83 66.2
14.2 H1 13800 <0.2 <0.03 29.1 17.5 21300 14.6 1170 0.08 8.89 112
14.2 H3 10200 <0.2 <0.03 23.2 12.5 16100 10.6 788 0.06 6.47 74.5
14.1 H4 6560 <0.2 <0.03 17.9 7.82 10700 6.95 426 0.04 4.24 51.3
14.1 H5 9500 <0.2 <0.03 22.5 12.8 13800 9.95 400 0.05 6.08 62.2
JL 8.5 H17 15200 <0.2 <0.03 33.3 23.2 24300 17.9 966 0.10 11.0 116 B
7.9 H18 14900 <0.2 <0.03 30.3 21.2 20100 15.5 713 0.08 10.2 96.9 B
TEC 9.79 0.99 43.4 31.6 35.8 0.18 22.7 121
PEC 33 4.98 111 149 128 1.06 48.6 459
15
9
Table 4. Polycyclic aromatic hydrocarbons measured in whole-sediment samples collected from the Haw River. All data are µg/kg dry weight (parts
per billion). For each compound, results are compared to threshold-effects concentration (TEC) guidelines of MacDonald et al. (2000) -- values
below which adverse effects to sensitive aquatic organisms are not expected to occur, and probable effects concentrations (PECs) -- values above
which adverse effects to sediment dwelling organisms may be expected. U = not detected.
River
Mile
Sample
ID Ben
zo(a
)anth
race
ne
Ben
zo(a
)pyre
ne
Ben
zo(b
)flu
ora
nth
ene
Ben
zo(g
,h,i
)per
yle
ne
Ben
zo(k
)flu
ora
nth
ene
Chry
sene
Dib
enzo
(a,h
)anth
race
ne
Flu
ora
nth
ene
Inden
o(1
,2,3
-cd)p
yre
ne
Phen
anth
rene
Pyre
ne
Sw
epso
nvil
le 37.4 H15 180 200 260 100 91 170 1 U 520 100 200 440
37.4 H16 190 220 300 110 110 240 1 U 570 110 190 480
37.2 H7 150 200 240 130 110 160 1 U 450 130 180 380
36.9 H6 150 190 230 140 110 190 1 U 410 130 130 350
36.8 H14 160 190 260 110 100 200 1 U 410 110 130 340
36.7 H13 130 160 230 95 77 160 1 U 330 95 100 290
Sax
apah
aw 33.1 H8 220 290 360 200 150 300 76 620 190 200 540
32.8 H9 180 180 220 110 74 130 1 U 310 97 97 310
32.2 H10 140 170 250 120 3 U 170 2 U 330 110 95 280
32.1 H11 170 200 240 120 110 200 1 U 420 120 120 350
32.0 H12 150 190 250 120 83 180 1 U 390 110 120 330
By
nu
m
14.3 H2 98 85 130 2 U 3 U 65 1 U 160 1 U 2 U 140
14.2 H1 170 160 200 110 4 U 120 2 U 330 100 150 270
14.2 H3 110 110 160 84 3 U 84 2 U 220 2 U 92 190
14.1 H4 120 100 150 77 3 U 84 1 U 210 71 71 190
14.1 H5 320 270 310 190 150 230 72 670 170 390 520
JL 8.5 H17 160 190 290 99 4 U 190 2 U 430 99 150 350
7.9 H18 110 130 200 2 U 3 U 120 2 U 250 2 U 2 U 210
TEC 108 150 166 33 423 204 195
PEC 1050 1450 1290 2230 1170 1520
16
9
Table 5. Response of Hyalella azteca in 28-d whole-sediment exposures, Chironomus dilutus in 10-d whole-sediment exposures, and
Ceriodaphnia dubia in 2-d elutriate exposures prepared from sediment samples collected from impounded reaches of the Haw River and to
a control sediment (WB). Means (standard error of the means in parentheses) with an asterisk (H1, 2, 16, and 17) within a column are
significantly different than the control (p <0.05).
River Site Amphipod Amphipod Amphipod
Midge Midge
Midge Cladoceran
Mile ID Survival (%) Length (mm) Biomass (mg)
Survival (%) AFDW (mg)
Biomass (mg) Survival (%)
Sw
epso
nvil
le 37.4 H15 95 (2.89) 4.74 (0.05) 5.18 (0.19)
93 (4.79) 1.09 (0.08)
9.95 (0.22) 100 (0.00)
37.4 H16 95 (2.89) 4.52 (0.24) 4.72 (0.75)
90 (0.00) NM
NM 10 (10.00)*
37.2 H7 95 (5.00) 4.43 (0.17) 4.43 (0.40)
98 (2.50) 0.84 (0.05)
8.21 (0.70) 80 (13.33)
36.9 H6 98 (2.50) 4.68 (0.14) 5.14 (0.46)
70 (17.80) 0.92 (0.07)
6.74 (1.84) 100 (0.00)
36.8 H14 95 (5.00) 4.77 (0.03) 5.25 (0.24)
98 (2.50) 1.20 (0.11)
11.82 (0.67) 100 (0.00)
36.7 H13 95 (5.00) 4.45 (0.09) 4.41 (0.16)
100 (0.00) 0.97 (0.21)
10.12 (2.09) 100 (0.00)
Sax
apah
aw 33.1 H8 93 (4.79) 4.69 (0.03) 4.84 (0.17)
100 (0.00) 1.55 (0.36)
15.44 (3.65) 90 (10.00)
32.8 H9 100 (0.00) 4.00 (0.12) 3.36 (0.28)
98 (2.50) 1.03 (0.22)
10.08 (2.19) 90 (10.00)
32.2 H10 98 (2.50) 4.25 (0.04) 3.98 (0.26)
98 (2.50) 0.64 (0.14)
6.30 (1.45) 90 (10.00)
32.1 H11 98 (2.50) 4.38 (0.12) 4.40 (0.36)
98 (2.50) 1.04 (0.14)
9.97 (1.04) 100 (0.00)
32.0 H12 98 (2.50) 4.36 (0.12) 4.24 (0.26)
100 (0.00) 0.94 (0.14)
9.37 (1.40) 100 (0.00)
Bynum
14.3 H2 80 (10.80)* 4.64 (0.06) 4.11 (0.61)
98 (2.50) 1.17 (0.13)
11.35 (0.90) 70 (15.28)*
14.2 H1 95 (2.89) 4.65 (0.03) 4.87 (0.24)
98 (2.50) 1.18 (0.03)
11.78 (0.50) 70 (15.28)*
14.2 H3 100 (0.00) 5.09 (0.13) 6.80 (0.54)
100 (0.00) 1.12 (0.09)
11.24 (0.94) 100 (0.00)
14.1 H4 95 (2.89) 4.92 (0.16) 5.86 (0.74)
95 (2.89) 1.01 (0.08)
9.56 (0.77) 90 (10.00)
14.1 H5 98 (2.50) 4.73 (0.14) 5.36 (0.60)
93 (2.50) 1.06 (0.19)
9.75 (1.64) 100 (0.00)
JL 8.5 H17 100 (0.00) 5.08 (0.22) 6.79 (0.84)
90 (4.08) 1.41 (0.21)
12.69 (1.92) 30 (15.28)*
7.9 H18 98 (2.50) 4.78 (0.24) 5.81 (0.87)
100 (0.00) 1.12 (0.21)
11.17 (2.07) 100 (0.00)
WB 93 (2.50) 4.52 (0.08) 4.43 (0.29)
96 (1.83) 0.83 (0.04)
8.04 (0.41) 100 (0.00)
* = Significantly different from control for that endpoint
NM = Not Measured (weigh boats melted)
Starting length of amphipods = 2.14 mm
Starting biomass of amphipods = 1.34 mg
17
Table 6. Water quality characteristics in 2-d elutriate exposures with Ceriodaphnia dubia prepared from Haw River sediment samples
and a control sediment (WB).
River
Mile
Temp
(oC)
Dissolved
oxygen
(mg/L)
Conductivity
(uS@25oC)
Alkalinity
CaCO3
Total
ammonia
(mg/L)
Unionized
ammonia
(mg/L)
Hardness
CaCO3
Sample
ID
pH
Sw
epso
nvil
le
37.4 H15 21.2 4.0 216 7.01 140 1.31 0.0058 92
37.4 H16 21.0 4.3 268 7.07 140 2.36 0.0119 80
37.2 H7 18.9 2.1 317 7.07 120 1.61 0.0070 90
36.9 H6 19.3 2.7 305 7.02 128 2.98 0.0118 80
36.8 H14 21.3 3.3 379 7.13 160 5.98 0.0353 116
36.7 H13 21.3 3.6 295 7.17 126 4.34 0.0281 84
Sax
apah
aw
33.1 H8 18.6 2.0 305 6.97 122 2.35 0.0079 90
32.8 H9 19.1 3.4 227 7.25 90 0.61 0.0040 80
32.2 H10 18.6 2.4 287 6.96 120 2.65 0.0087 80
32.1 H11 21.6 3.7 214 7.07 88 1.45 0.0076 82
32 H12 21.0 3.3 231 7.12 90 1.68 0.0095 76
Bynum
14.3 H2 21.6 3.2 244 7.13 110 1.53 0.0092 80
14.2 H1 19.3 2.1 324 7.03 150 5.24 0.0213 90
14.2 H3 18.8 2.5 299 6.98 176 3.54 0.0123 82
14.1 H4 21.6 3.2 308 7.04 140 3.10 0.0152 90
14.1 H5 21.6 3.5 257 6.97 106 2.33 0.0097 90
JL 8.5 H17 19.9 2.7 373 6.94 160 2.48 0.0085 120
7.9 H18 21.0 3.6 254 7.05 100 3.03 0.0146 80
WB 22.0 3.6 225 7.03 88 2.20 0.0109 84
18
Table 7. Elemental contaminant concentrations (µg/L) of 2-d elutriate exposures with Ceriodaphnia dubia prepared from Haw River
sediment samples and a control sediment (WB).
B = aluminum, iron and manganese were detected in the blank, but at concentration much lower than the actual samples; the presence
of these metals in the blank should not affect interpretation of results
J = less than reporting limit (estimated value)
River Mile Sample ID Al As Cd Cr Cu Fe Pb Mn Ni Zn
Sw
epso
nvil
le
37.4 H15 247 B <2.8 <0.36 <1.0 <1.60 1280 B <1.9 8540 B 2.0 J 10.3
37.4 H16 1040 B <2.8 <0.36 <1.0 4.30 J 1640 B 2.4 J 3730 B 3.2 J 33.3
37.2 H7 2200 B <2.8 <0.36 <1.0 16.4 5760 B 21.5 4050 B 3.5 J 70.6
36.9 H6 3120 B <2.8 <0.36 <1.0 6.60 J 8890 B 25.2 3700 B 3.8 J 50.8
36.8 H14 60 BJ <2.8 <0.36 <1.0 <1.60 1050 B <1.9 6790 B 6.0 J 6.1 J
36.7 H13 861 B <2.8 <0.36 9.3 J 5.60 J 4100 B 3.0 J 5890 B 23.5 59.6
Sax
apah
aw
33.1 H8 880 B <2.8 <0.36 <1.0 <1.60 6920 B 19.6 4640 B <1.8 13.5
32.8 H9 2670 B <2.8 <0.36 3.2 J 19.8 3570 B 169 2640 B 6.9 J 73.8
32.2 H10 5220 B <2.8 <0.36 <1.0 <1.60 15600 B 72.8 4140 B <1.8 32.0
32.1 H11 110 B <2.8 <0.36 <1.0 3.20 J 902 B <1.9 2650 B <1.8 15.6
32 H12 540 B <2.8 <0.36 <1.0 2.90 J 1340 B 17.7 2960 B <1.8 45.2
Bynum
14.3 H2 2550 B <2.8 <0.36 1.9 J <1.60 5620 B 4.1 J 3510 B <1.8 16.2
14.2 H1 1200 <2.8 <0.36 <1.0 <1.60 9250 8.1 J 8110 3.1 J 54.0
14.2 H3 1110 B <2.8 <0.36 <1.0 <1.60 6700 B 8.3 J 4910 B <1.8 15.2
14.1 H4 1220 B <2.8 <0.36 <1.0 2.20 J 6530 B 3.0 J 5080 B 2.1 J 25.1
14.1 H5 262 B <2.8 <0.36 <1.0 <1.60 748 B <1.9 2710 B <1.8 38.3
JL 8.5 H17 96 BJ <2.8 <0.36 <1.0 <1.60 1680 B <1.9 8040 B 1.8 J 8.0 J
7.9 H18 1160 B <2.8 <0.36 <1.0 5.70 J 3510 B 3.0 J 5990 B 4.4 J 54.3
WB 216 B 5.6 JB <0.36 <1.0 4.20 J 2450 B 2.0 J 7480 6.2 J 36.1
19
Table 8. Water quality characteristics of pore water isolated from Haw River sediment samples and a control sediment (WB).
River
Mile
Sample
ID
Temp
(oC)
Dissolved
oxygen
(mg/L)
Conductivity
(uS@25oC) pH
Alkalinity
CaCO3
Total
ammonia
(mg/L)
Unionized
ammonia
(mg/L)
Hardness
CaCO3
Sw
epso
nvil
le
37.4 H15 19.2 2.8 807 7.05 850 5.22 0.0220 370
37.4 H16 19.3 2.9 1084 7.09 424 10.0 0.0465 320
37.2 H7 16.1 2.8 742 7.06 292 2.2 0.0075 220
36.9 H6 17.8 2.3 671 6.97 300 5.8 0.0184 170
36.8 H14 19.2 1.8 1070 7.01 534 17.4 0.0669 320
36.7 H13 17.1 2.2 889 7.01 434 12.0 0.0395 260
Sax
apah
aw
33.1 H8 17.7 2.5 641 6.94 316 3.64 0.0107 200
32.8 H9 17.5 2.6 361 7.16 160 0.97 0.0046 130
32.2 H10 16.4 2.0 551 6.94 250 5.06 0.0135 134
32.1 H11 17.7 3.3 473 7.11 220 3.61 0.0156 148
32 H12 18.7 2.6 582 7.05 280 4.24 0.0172 190
Bynum
14.3 H2 17.3 2.2 576 7.06 280 3.55 0.0133 182
14.2 H1 16.1 2.4 983 7.00 500 14.3 0.0427 260
14.2 H3 18.2 3.4 726 7.02 562 6.72 0.0246 402
14.1 H4 16.9 2.6 703 7.03 346 6.56 0.0223 204
14.1 H5 17.7 4.0 590 7.02 276 5.52 0.0195 164
JL 8.5 H17 19.3 2.5 1008 6.99 520 17.7 0.0655 310
7.9 H18 19.3 2.3 808 7.00 400 10.5 0.0398 266
WB 18.6 3.4 635 7.12 254 8.80 0.0417 234
20
Table 9. Elemental contaminant concentrations (µg/L) of pore water isolated from Haw River whole-sediment samples and a control
sediment (WB).
D = sample result based on analyses of dilution
J = less than reporting limit (estimated value)
River Mile Sample ID Al As Cd Cr Cu Fe Pb Mn Ni Zn
Sw
epso
nvil
le
37.4 H15 639 <2.8 <0.36 <1.0 <1.60 56900 6.2 J 39700 D <1.8 27.7
37.4 H16 2260 <2.8 <0.36 <1.0 <1.60 39500 8.4 J 14000 13.4 16.6
37.2 H7 2100 <2.8 <0.36 <1.0 4.60 J 25400 13.2 10300 1.8 J 77.7
36.9 H6 229 <2.8 <0.36 <1.0 <1.60 15000 2.9 J 11300 <1.8 14.6
36.8 H14 1440 <2.8 <0.36 <1.0 <1.60 46700 7.6 J 20700 <1.8 33.8
36.7 H13 387 <2.8 <0.36 <1.0 <1.60 28600 <1.9 16200 <1.8 6.0 J
Sax
apah
aw
33.1 H8 4870 <2.8 <0.36 30.0 9.80 J 45300 22.7 12200 1.9 J 64.0
32.8 H9 17000 <2.8 <0.36 119 53.0 28600 46.6 4900 9.6 J 120
32.2 H10 10100 <2.8 <0.36 6.4 J 15.8 39900 23.0 8950 2.6 J 60.2
32.1 H11 499 <2.8 <0.36 <1.0 <1.60 9370 2.2 J 6280 4.6 J 19.2
32 H12 1360 <2.8 <0.36 <1.0 6.40 J 17000 4.8 J 7590 2.2 J 42.1
Bynum
14.3 H2 742 <2.8 <0.36 <1.0 <1.60 12300 2.1 J 8900 3.2 J 9.3 J
14.2 H1 1160 <2.8 <0.36 <1.0 <1.60 43800 6.3 J 28000 <1.8 49.1
14.2 H3 1000 <2.8 <0.36 <1.0 <1.60 26500 3.6 J 15900 <1.8 13.0
14.1 H4 690 <2.8 <0.36 <1.0 <1.60 22600 3.1 J 14900 <1.8 23.3
14.1 H5 529 <2.8 <0.36 <1.0 <1.60 16200 <1.9 8410 <1.8 8.9 J
JL 8.5 H17 1930 <2.8 <0.36 <1.0 <1.60 58200 6.6 J 21600 3.5 J 59.9
7.9 H18 3280 <2.8 <0.36 <1.0 <1.60 54500 10.9 15000 <1.8 60.7
WB 1810 B 9.3 JB <0.36 <1.0 23.3 28700 B 18.4 20900 19.2 97.9
21
Table 10. Mean water quality characteristics of overlying water in whole-sediment toxicity tests with Hyalella azteca and Haw River
sediments and a control sediment (WB).
River
Mile
Sample
ID
Temp
(oC)
Dissolved
oxygen
(mg/L)
Conductivity
(uS@25oC) pH
Alkalinity
CaCO3
Total
ammonia
(mg/L)
Unionized
ammonia
(mg/L)
Hardness
CaCO3
Sw
epso
nvil
le
37.4 H15 23 5.05 247 7.99 109 0.980 0.0206 129
37.4 H16 23 4.73 243 7.87 110 0.988 0.0235 116
37.2 H7 23 5.24 244 8.01 100 0.336 0.0066 112
36.9 H6 23 5.18 239 7.99 95 0.093 0.0017 113
36.8 H14 23 5.07 245 7.93 94 1.604 0.0295 117
36.7 H13 23 5.58 238 8.04 98 1.056 0.0205 118
Sax
apah
aw
33.1 H8 23 5.17 242 8.00 100 0.621 0.0113 114
32.8 H9 23 6.04 231 8.05 100 0.157 0.0034 112
32.2 H10 23 5.45 236 7.97 97 0.568 0.0090 111
32.1 H11 23 5.13 235 7.93 99 0.330 0.0067 112
32 H12 23 4.95 237 7.96 97 0.401 0.0076 116
Bynum
14.3 H2 23 5.19 238 8.04 96 0.505 0.0034 117
14.2 H1 23 5.22 240 7.89 102 1.622 0.0246 112
14.2 H3 23 5.19 241 7.89 98 0.869 0.0137 118
14.1 H4 23 5.15 239 7.98 99 0.753 0.0145 114
14.1 H5 23 4.91 237 7.88 101 0.851 0.0158 115
JL 8.5 H17 23 5.22 240 7.95 106 0.992 0.0194 115
7.9 H18 23 5.46 234 7.98 102 0.993 0.0195 115
WB 23 6.11 231 8.23 96 1.730 0.0269 104
22
Table 11. Mean water quality characteristics of overlying water in whole-sediment toxicity tests with Chironomus dilutus and Haw
River sediments and a control sediment (WB).
River
Mile
Sample
ID
Temp
(oC)
Dissolved
oxygen
(mg/L)
Conductivity
(uS@25oC) pH
Alkalinity
CaCO3
Total
ammonia
(mg/L)
Unionized
ammonia
(mg/L)
Hardness
CaCO3
Sw
epso
nvil
le
37.4 H15 23 5.28 252 8.03 105 1.066 0.0558 119
37.4 H16 23 5.32 252 8.08 110 1.173 0.0699 111
37.2 H7 23 5.55 239 8.06 95 0.393 0.0203 105
36.9 H6 23 5.68 236 8.08 97 0.180 0.0113 105
36.8 H14 23 5.16 250 8.07 93 1.826 0.0897 108
36.7 H13 23 4.97 244 8.03 101 1.650 0.0826 112
Sax
apah
aw
33.1 H8 23 5.61 235 8.02 95 0.626 0.0288 107
32.8 H9 23 5.97 229 8.14 97 0.142 0.0087 103
32.2 H10 23 5.36 234 7.97 93 3.610 0.1730 103
32.1 H11 23 5.32 233 8.12 97 0.405 0.0233 106
32 H12 23 4.97 239 8.03 96 0.569 0.0284 103
Bynum
14.3 H2 23 5.35 235 7.99 91 0.569 0.0111 103
14.2 H1 23 5.28 243 7.92 100 1.8405 0.0708 101
14.2 H3 23 5.06 242 7.89 100 1.073 0.0413 106
14.1 H4 23 5.28 238 8.02 98 0.806 0.0392 108
14.1 H5 23 4.79 244 7.97 103 1.278 0.0573 107
JL 8.5 H17 23 4.75 256 7.94 106 1.510 0.0662 108
7.9 H18 23 5.18 238 7.99 102 1.366 0.0651 108
WB 23 5.94 234 8.07 91 0.908 0.0690 103
23
16
Two of the 100% elutriate samples that were found to be particularly toxic to C. dubia (H16 and
H17) were re-tested in a dilution series. Sample site H16 is in the portion of Big Alamance Creek
that is flooded by the impoundment created by the dam at Swepsonville. When re-tested in the
dilution series, C. dubia survival was 40% in the 100% elutriate with 80% survival in the first
dilution, a 50% elutriate sample. Site H17 is from a shoal in the headwaters of Jordan Lake.
When re-tested in the dilution series, C. dubia survival was 70% in the 100% elutriate with 100%
survival in the first dilution, a 50% elutriate sample.
Although the elutriates and pore-water samples are not surface waters, we compared elemental
contaminant concentrations in these media to State water quality standards and action levels
(Table 12). This is not a regulatory application of the standards; it is rather a comparison of test
results to the standards as toxicological benchmarks, or estimates of safe water column
concentrations. Chromium in pore water at site H9 in the Saxapahaw Dam impoundment was
measured at 119 μg/L. Copper, lead, and zinc in the elutriate and pore water samples exceeded
State standards infrequently but most commonly in samples from the Saxapahaw Dam
impoundment. This is an indication that aggressive re-suspension of sediments like those tested
could temporarily impair surface water quality.
Table 12. Haw River sediment elutriates and pore water exceedences of North Carolina water
quality standards or action levels for elemental contaminants (NCDENR 2004). Analytical data
for elutriates and pore water are in Tables 7 and 9.
Contaminant
Standard or Action
Level
Elutriate samples in
excess of threshold (%)
Pore water in excess of
threshold (%)
Arsenic 50 μg/L 0 (max <2.8 μg/L) 0 (max <2.8 μg/L)
Cadmium 2 μg/L 0 (max <0.36 μg/L) 0 (max <0.36 μg/L)
Chromium 50 μg/L 0 (max = 9.3 μg/L) 6 (max = 119 μg/L)
Copper 7 μg/L 11 (max = 19.8 μg/L) 17 (max = 53.0 μg/L)
Lead 25 μg/L 17 (max = 169 μg/L) 6 (max = 46.6 μg/L)
Nickel 88 μg/L 0 (max = 23.5 μg/L) 0 (max = 13.4 μg/L)
Zinc 50 μg/L 33 (max = 73.8 μg/L) 33 (max = 120μg/L)
Collectively, the whole-sediment chemistry results indicate minimal contamination which is
consistent with the lack of toxicity in the whole-sediment samples in the amphipod and midge
tests (Table 2).
A potential explanatory variable for the toxicity of elutriates to C. dubia at sites H1, H2, H16 and
H17 (Table 5) is manganese in elutriates (Table 7). Stubblefield and Hockett (2000) report a
geometric mean LC50 (median lethal concentration) from eight manganese toxicity tests with C.
dubia of 15.4 mg/L (data normalized to a hardness of 50 mg/L as CaCO3). Similarly, Lasier et
24
25
al. (2000) report a C. dubia LC50 of 14.5 mg/L for manganese at a hardness of 93 mg/L as
CaCO3. The Haw River sediment elutriates ranged in hardness from 76 to 120 mg/L as CaCO3
(Table 6). To approximate a threshold at which lethal effects may begin, we multiplied the LC50
reported by Lasier et al. (2000) by 0.5. This yields an estimated lethal effects threshold of 7.2
mg/L (or 7,200 μg/L) for manganese. Evaluation of acute toxicity data over a large number of
tests and species has generally shown that dividing an LC50 or EC50 by 2 (i.e., multiplying by
0.5) provides an estimate of a concentration near or below the lethality threshold. The technical
rationale for dividing by 2 is found in the Federal Register notice soliciting comment on
USEPA’s methodology for deriving water quality criteria (43 FR 21506, May 18, 1978)
(Stephan et al. 1985). Because the estimate was derived for a large battery of species and
chemicals, it may not be accurate for particular individual species and chemical combinations,
but it is useful for risk screening purposes.
Elutriate manganese concentrations from two of the four sites exhibiting toxicity (H1, 8.1 mg/L),
and H17 (8.0 mg/L) exceeded the 7.2 mg/L estimated lethal effects threshold concentration for
C. dubia and manganese (Table 7). The other two samples exhibiting toxicity, H2 (3.5 mg/L),
and H16 (3.7 mg/L) did not exceed this threshold. Manganese is a naturally occurring and very
common element in soils and surface waters; among the heavy metals, only iron is more
abundant in the earth’s crust (ATSDR 2000). Impoundments have the potential to increase metal
concentrations due to soil disturbance and increased surface area exposed to water. Elevated
manganese was the number one problem associated with water quality downstream of Tennessee
dams in a recent evaluation (Arnwine et al 2006). Anthropogenic enrichment of manganese can
occur through burning fossil fuels, steel production, battery manufacturing, animal feed
supplements, fertilizers, wastewater treatments plants (using potassium permanganate),
manganese-based fungicides, and antiknock fuel additives (ATSDR 2000).
If it becomes important to more definitively assess the cause of toxicity in the sediment elutriate
samples, there are well established toxicity identification evaluation (TIE) approaches that can be
applied (USEPA 1993 b, c, Besser at al. 1998, Boucher and Watzin 1999). Non-toxic elutriate
samples could be spiked with increasing concentrations of manganese to determine toxic
concentrations of these constituents to C. dubia in a manner inclusive of site-specific elutriate
chemistry. Procedures to reduce concentrations of elutriate components (e.g. sequester metals
like manganese) also exist to investigate how their presence or absence explains toxicity.
Elutriate tests aid in the evaluation of the effects of suspended sediments (e.g., dredged material
evaluations) within the water column. Mobilization of sediments we tested may be a short-term
water column concern based on the elutriate toxicity test results. While sediment re-suspension
and contaminant release in the elutriate tests may be near a worst case simulation of actual
conditions following sediment disturbing activities, additional synthesis is needed to characterize
the nature and magnitude of this issue. In particular, data on the modeled or measured sediment
re-suspension caused by specific sediment disturbing activities will help put the elutriate test
results in context for normal sediment management practices. The joint U.S. EPA and U.S.
Army Corps of Engineers Inland Testing Manual (USEPA/USACE 1998) contains sediment fate
models which may be helpful for this purpose. It would also be useful to evaluate the relative
sensitivity of C. dubia to other freshwater organisms, particularly those resident to the Haw
River.
26
Restoration Systems LLC (2008) examined sediment accumulation in the dams we evaluated.
They concluded that the Swepsonville Dam is not very effective at retaining fine sediments and
that removal of that dam would likely have a de minimis impact on sediment mobilization. From
a pollutant perspective, our surface samples that were targeted to depositional areas are
considered to represent the upper range of expected contaminant concentrations.
Restoration Systems’ LLC (2008) review of the Saxapahaw Dam indicates it has been effective
at trapping sediment with appreciable accumulation into a distinct wedge of fine sediment,
starting ~1000 feet from the dam. Given the site’s character of deposition and the watershed’s
industrial history, they recommended that the sediment wedge be heavily sampled and analyzed
for pollutants in a depth profile because of the likelihood of historic sediment accumulation and
the projection that considerable channel incision (on the order of 10+ feet) is likely to occur if
the dam was completely removed (without dredging stored sediments). From a pollutant
perspective, our surface samples that were targeted to depositional areas are considered to
represent only the recently deposited material at this location.
Restoration Systems’ LLC (2008) review of the Bynum Dam indicated the river at that location
is characterized by fairly coarse bed material, including large rock outcrops which produce a
pattern of patchy, localized sediment retention and island formation. The Bynum impoundment
has not been an effective sediment trap through time and the majority of the trapped sediment is
sand and gravel. It was suggested that removal of that dam would likely have a de minimis
impact on sediment mobilization with the majority of movement coming from erosion of islands
near the dam, at least the edges of which are made of flocculent depositional material. We
targeted these edges in our sampling, so from a pollutant perspective our surface samples that
were targeted to depositional areas are considered to represent the upper range of expected
contaminant concentrations in material that could be transported downstream.
In summary, eighteen whole-sediment samples from within the impounded reaches of
Swepsonville Dam, Saxapahaw Dam, Bynum Dam, and B. Everett Jordan Dam were collected in
June 2008. All samples were analyzed for elemental contaminants and polycyclic aromatic
hydrocarbons. All samples were also assessed with a battery of toxicity tests. Elemental
contaminant concentrations in whole sediments were below those of toxicological significance.
One or more sediment PAHs with freshwater sediment threshold effects (TEC) screening values
(MacDonald et al. 2000) were in excess of TECs at 17 of the 18 sites, but no samples exceeded
the probable effects concentrations (PECs). Survival of Hyallela azteca (freshwater amphipod)
exposed to sediments from site H2 in the Bynum Dam impounded reach was 80% and
statistically lower than controls in 28-d toxicity tests; amphipod growth was not affected at this
or any other site. Whole sediments had no significant effect on survival or growth in 10-d tests
with Chironomus dilutus (freshwater midge) at any of the 18 sites. Results indicate the
contaminants associated with the whole-sediment samples were not chronically toxic to
amphipods or midge. In 2-d sediment elutriate (water-extractable fraction) tests with
Ceriodaphnia dubia (freshwater cladoceran), statistically-significant reductions in survival
occurred in four of the 18 exposures (H1 and H2 within the Bynum Dam impounded reach, site
H16 in the flooded portion of Big Alamance Creek, and site H17 in the headwaters of Jordan
Lake). Chromium in pore water at site H9 in the Saxapahaw impoundment was measured at 119
μg/L; the State standard is 50 μg/L. Copper, lead, and zinc in the elutriate and pore water
samples exceeded State standards infrequently but most commonly in sediments collected from
the Saxapahaw Dam impoundment. This is an indication that aggressive re-suspension of
sediments like those tested could temporarily impair surface water quality.
These data and surveys of sediment physical characteristics (Restoration Systems, LLC. 2008),
volume, and likelihood of movement can be used together to infer the impacts the different types
of sediments disturbing activities on short-term water column chemistry. While sediment re-
suspension and contaminant release in the elutriate tests may be near a worst case simulation of
actual conditions following sediment disturbing activities, additional synthesis is needed to
characterize the nature and magnitude of this issue. In particular, data regarding the modeled or
measured sediment re-suspension caused by specific sediment disturbing activities (e.g.,
dredging, dam alterations, dam removal, etc.) will help put the elutriate test results in context for
a range of sediment management practices.
Management Recommendations
The study was intended to provide data that facilitates evaluation of dam removal actions. We
will provide these data to dam owners, the North Carolina Dam Removal Task Force, and other
interested stakeholders with recommendations on sediment quality which will help them further
prioritize and plan management of these structures.
A concurrent assessment of sediment physical characteristics and volume was conducted by
Restoration Systems, LLC (2008). Our data and theirs could be further integrated to evaluate
sediment transport scenarios to better inform sediment management at these dams.
Additional data exploration with USGS could be conducted to investigate the source(s) of the
reduced test organism survival in four of the sediments. Pairwise correlations among the C.
dubia survival results and sediment and elutriate chemical analyses may be helpful, but there is
not much resolution in the toxicity test results to support this assessment. Concentrations of
individual metals in sediment, total PAHs, and individual PAHs were not a concern. Additional
analyses of sediment quality may include calculating mean quotients based on probable effects
concentrations(PEC-Q) to provide an overall measure of chemical contamination and to support
an evaluation of the combined effects of multiple contaminants (MacDonald et al. 2000; USEPA
2000b). Relationships between toxicity and concentrations of PAHs in sediment samples could
be further examined using equilibrium partitioning sediment guideline toxic units (ESGTU;
USEPA 2003). The ESGTUs are a way of summarizing many PAHs compounds into one
representative number. An ESGTU is basically the organic carbon normalized concentration of a
chemical divided by a toxicity threshold (this is a toxic unit for the specific chemical). Then the
ESGTU for specific chemicals are summed for each sample yielding ΣESGTUs. These
additional analyses will obviously not change the conclusion that sediments were either non-
toxic or of low toxicity in solid phase exposures, but they may help explain the patterns and
significance of the low level PAH contamination we measured.
27
References
American Society for Testing and Materials. 2007. Standard test method for measuring the
toxicity of sediment-associated contaminants with freshwater invertebrates (E1706-05). In
ASTM Annual Book of Standards, Vol. 11.06, West Conshohocken, PA.
Arnwine, D.H., K.J. Sparks and R.R. James. 2006. Probabilistic monitoring of streams below
small impoundments in Tennessee. Tennessee Department of Environment and Conservation,
Division of Water Pollution Control, Nashville, TN.
ATSDR. 2000. Toxicological profile for manganese. Agency for Toxic Substances and Disease
Registry, Division of Toxicology/Toxicology Information Branch, Atlanta, GA.
Augspurger, T. and M. Cantrell. 2004. Sediment Contaminants at Dillsboro Reservoir: Report on
site assessment and sediment analyses. Final. U.S. Fish and Wildlife Service, Raleigh, NC.
Augspurger, T.P., C.G. Ingersoll N.E. Kemble, J.L Kunz and S.E. Ward. 2007. Sediment Quality
within the Impounded Reaches of Cape Fear River Locks and Dams. U.S. Fish and Wildlife
Service and U.S. Geological Survey. USFWS, Raleigh, NC.
Besser, J.M., C.G. Ingersoll, E.N. Leonard and D.R. Mount. 1998. Effect of zeolite on toxicity of
ammonia in freshwater sediments: Implications for toxicity identification evaluation procedures.
Environ Toxicol Chem 17: 2310–2317.
Boucher, A.M and M.C. Watzin. 1999. Toxicity identification evaluation of metal-contaminated
sediments using an artificial pore water containing dissolved organic carbons. Environ Toxicol
Chem 18: 509-518.
Foth, H.D. L.V. Withee, H.S. Jacobs and S.J. Thien. 1982. Laboratory Manual for Introductory
Soil Science. Brown Company Dubuque, IA, pp. 13-26.
Freeman, M.C., C.M. Pringle, E.A. Greathouse and B.J. Freeman. 2003. Ecosystem-level
consequences of migratory faunal depletion caused by dams. American Fisheries Society
Symposium 35: 255-266.
Gee, G.W. and J.W. Bauder. 1986. Particle-size analysis. In A. Klute, ed., Methods of Soil
Analysis. No. 9, Part 1, Agronomy Series. American Society of Agronomy, Madison, WI, pp.
383-411.
Ingersoll C.G., D.D. MacDonald, W.G. Brumbaugh, B.T. Johnson, N.E. Kemble, J.L. Kunz,
T.W. May, N. Wang, J.R. Smith, D.W. Sparks and S.D. Ireland. 2002. Toxicity assessment of
sediments from the Grand Calumet River and Indiana Harbor Canal in northwestern Indiana.
Arch Environ Contam Toxicol 43:153-167.
28
Kemble, N.E., J.M. Besser, W.G. Brumbaugh, E.L. Brunson, F.J. Dwyer, C.G. Ingersoll, D.P.
Monda and D.F. Woodward. 1994. Toxicity of metal-contaminated sediments from the upper
Clark Fork River, MT, to aquatic invertebrates in laboratory exposures. Environ Toxicol Chem
13: 1985-1997.
Lasier P.J., P.V. Winger and K.J. Bogenrieder. 2000. Toxicity of manganese to Ceriodaphnia
dubia and Hyalella azteca. Arch Environ Contam Toxicol. 38: 298–304.
MacDonald, D.D., C.G. Ingersoll and T.A. Berger. 2000. Development and evaluation of
consensus-based sediment quality guidelines for freshwater ecosystems. Arch Environ Contam
Toxicol 39: 20-31.
MacDonald, D.D. and C.G. Ingersoll. 2002a. A guidance manual to support the assessment of
contaminated sediments in freshwater ecosystems. Volume I - An ecosystem-based framework
for assessing and managing contaminated sediments. EPA-905-B02-001-A. USEPA, Great
Lakes National Program Office, Chicago, IL.
MacDonald, D.D. and C.G. Ingersoll. 2002b. A guidance manual to support the assessment of
contaminated sediments in freshwater ecosystems. Volume II - Design and implementation of
sediment quality investigations. EPA-905-B02-001-B. USEPA, Great Lakes National Program
Office, Chicago, IL.
MacDonald, D.D., C.G. Ingersoll, D.E. Smorong, R.A. Lindskoog, G. Sloane and T. Biernacki.
2003. Development and Evaluation of Numerical Sediment Quality Assessment Guidelines for
Florida Inland Waters. Florida Department of Environmental Protection. Tallahassee, FL.
Mount, D.R., D.D. Gulley, J.R. Hockett, T.D. Garrison and J.M. Evans. 1997. Statistical models
to predict the toxicity of major ions to Ceriodaphnia dubia, Daphnia magna and Pimephales
promelas (fathead minnows). Environ Toxicol Chem 16: 2009–2019.
Neves, R.J., A.E. Bogan, J.D. Williams, S.A. Ahlstedt and P.W. Hartfield. 1997. Status of
mollusks in the southeastern United States: A downward spiral of diversity. Pages 31-85 in G.W.
Benz and D.E. Collins, eds. Aquatic Fauna in Peril: The Southeastern Perspective. Special
Publication 1, Southeast Aquatic Research Institute, Lenz Designs and Communications,
Decatur, GA.
North Carolina Department of Environment and Natural Resources. 2004. “Redbook”
Classifications and Water Quality Standards Applicable to Surface Waters and Wetlands of
North Carolina (15A NCAC 2B .0100 and .0200). Department of Environment and Natural
Resources, Division of Water Quality, Raleigh, NC.
North Carolina Division of Water Quality. 1999. Basinwide assessment report: Cape Fear River
basin. Environmental Sciences Branch, Water Quality Section, Raleigh, NC.
Restoration Systems, LLC. 2008. Preliminary sediment survey, Haw River Dams, Alamance and
Chatham Counties, North Carolina. Restoration Systems, LLC, Raleigh, NC.
29
Richter, B.D., D.P. Braun, M.A. Mendelson and L.L. Master. 1997. Threats to imperiled
freshwater fauna. Conservation Biology 11: 1081-1093.
Riggsbee, J.A. 2006. Short-term nutrient and sediment fluxes following dam removal. PhD Diss.
University of North Carolina, Environmental Sciences and Engineering, Chapel Hill, NC.
Schumacher, B.A. 2002. Methods for the determination of total organic carbon (TOC) in soils
and sediments. NCEA-C- 1282 EMASC-001. U.S. Environmental Protection Agency,
Environmental Sciences Division, National Exposure Research Laboratory, Las Vegas, NV.
Snedecor GW, Cochran WG. 1982. Statistical Methods. 7th ed. The Iowa State University Press.
Ames, IA.
Statistical Analysis Systems. 2001. SAS® User's Guide: Statistics, Version 5 Edition. Cary, NC.
Stephan, C.E., D.I. Mount, D.J. Hansen, J.H. Gentile, G.A. Chapman and W.A. Brungs. 1985.
Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic
Organisms and their Uses. U.S. Environmental Protection Agency, Office of Research and
Development Washington, DC.
Stubblefield, W.A. and J.R. Hockett. 2000. Derivation of a Colorado state manganese table
value standard for the protection of aquatic life. ENSR Corporation, Fort Collins, CO.
U.S. Environmental Protection Agency/U.S. Army Corps of Engineers. 1998. Evaluation of
dredged material proposed for discharge in waters of the U.S. - Testing Manual. EPA-823-B-98-
004, Washington, DC.
U.S. Environmental Protection Agency. 1993a. Assessment and remediation of contaminated
sediments (ARCS) program. Biological and chemical assessment of contaminated Great Lakes
sediment. EPA 905/R-93/006, Chicago, IL.
U.S. Environmental Protection Agency. 1993b. Methods for aquatic toxicity identification
evaluations: Phase II, Toxicity identification procedures for samples exhibiting acute and chronic
toxicity. EPA-600/R-92/080. Environmental Research Laboratory, Duluth, MN.
U.S. Environmental Protection Agency. 1993c. Methods for aquatic toxicity identification
evaluations: Phase III, Toxicity confirmation procedures for samples exhibiting acute and
chronic toxicity. EPA-600/R-92/081. Environmental Research Laboratory, Duluth, MN.
U.S. Environmental Protection Agency. 2000a. Methods for measuring the toxicity and
bioaccumulation of sediment-associated contaminants with freshwater invertebrates, second
edition, EPA/600/R-99/064, Duluth, MN and Washington, DC.
U.S. Environmental Protection Agency. 2000b. Prediction of sediment toxicity using consensus-
based freshwater sediment quality guidelines. EPA 905/R-00/007, Chicago, IL.
30
USEPA. 2003. Procedures for the derivation of equilibrium partitioning sediment benchmarks
(ESBs) for the protection of benthic organisms: PAH Mixtures. EPA-600-R-02-13, Office of
Research and Development, Washington DC.
Watters, G.T. 2000. Freshwater mussels and water quality: A review of the effects of
hydrologic and instream habitat alterations. Proceedings of the First Freshwater Mollusk
Conservation Society Symposium, 1999. Pages 261-274. Ohio Biological Survey.
Wenning R.J., G. Batley, C.G. Ingersoll and D.W. Moore, editors. 2005. Use of Sediment Quality
Guidelines and Related Tools for the Assessment of Contaminated Sediments. SETAC Press,
Pensacola FL.
31