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2

2. Synopsis:

2.1.Title: The impact of Coal Combustion Products on the quality of water resources in North 

Carolina

2.2.Project Type: Research

2.3.Focus Categories: WQL , HYDGEO, TS

2.4.Research Category (required by the USGS): Water Quality

2.5.Keywords: coal ash, water quality, contamination, metals, monitoring and regulations

2.6.Proposed Start Date: 03/01/2011 and End Date: 02/29/2012.

2.7.Investigator(s): 

PI: Avner Vengosh, Professor, Division of Earth and Ocean Sciences, Nicholas School of the 

Environment, Duke University, Durham, NC 27708; Phone: (919) 681-8050; Fax (919) 684-

5833; E-mail: vengosh@duke.edu

Co-PI: Heileen Hsu-Kim, Assistant Professor, Department of Civil & Environmental Engineering, 

Pratt School of Engineering, Duke University, Durham, NC 27708; Phone: (919) 660-5109; Fax: 

(919) 660-5219; email: hsukim@duke.edu

2.8.Congressional District of Duke University performing the research: 

Congressional District 4

2.9.Abstract:

Coal combustion products (CCPs) are known to contain toxic elements such as arsenic, 

selenium, and mercury. While a subset of CCPs is recycled for beneficial purposes, the majority 

of the waste is stored in more than 350 landfills and storage ponds across the nation. CCPs are 

not classified as hazardous waste, and as a result, these landfills and storage ponds are 

typically unlined and susceptible to leaks and failures. Moreover, discharge of effluents from 

storage ponds may pose an ecological hazard if they contain toxic elements leached from 

CCPs. Despite the risks, the hazards stemming from ongoing CCPs waste disposal practices 

have not been fully evaluated. In a recent nationwide survey of 431 holding ponds, 49 have 

been assigned a “high hazard potential” rating by the EPA, and approximately one-quarter of 

these are located in North Carolina. The objectives of this project are (1) determine the 

magnitude of CCPs contamination of associated water resources in NC; (2) evaluate the fate 

(e.g., retardation) of key contaminants (arsenic, selenium, boron, strontium, barium, 

methylmercury) in water resources and the environmental factors that control these variations; 

(3) establish reliable monitoring tools for evaluating the impact of CCPs on NC water resources 

that can be used for state regulations; and (4) provide the scientific base for possible future 

state regulation on CCPs storage in NC. The project will include systematic sampling of 

effluents and affected surface water, pore water in lake sediments and groundwater in the 

vicinity of CCP storage ponds in NC, measurements of major elements, trace-metals and boron 

isotopes composition for tracing leachates generated from CCPs, and modeling of species 

distribution in the investigated water. An outcome of this research will be a scientific evaluation 

of the environmental impacts of CCPs on the water resources in NC and establishing reliable 

monitoring tools for state regulation of the fate of contaminants that are generated from CCPs in 

NC. This information will also be needed for future regulatory actions expected from the EPA on 

CCPs disposal practices. 
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3. Project Description

3.1. Title: The impact of Coal Combustion Products on the quality of water resources in North 

Carolina

3.2. Statement of the regional or state water problem(s).

Over five hundred power plants nationwide generate approximately 130 million tons of 

Coal Combustion Products (CCPs) each year, 43% of which is recycled into other materials 

while the remaining 70 million tons is stored in 194 landfills and 161 ponds in 47 states [2]. 

CCPs represent the largest industrial waste stream in the U.S.; however, they are not classified 

as hazardous waste. As a result, disposal storage ponds and landfills are generally unlined and, 

in many instances, may not be adequately monitored with respect to their effects to groundwater 

and surface waters. One of the major potential hazards of coal ash storage ponds is the 

continuous leaching of contaminants and their transport to the hydrological system. Because 

monitoring results from discharges of holding ponds and landfills are scant, the long-term 

environmental impacts of leachates generated from CCPs are unknown. In a recent nationwide 

survey of 431 holding ponds, 49 have been assigned a “high hazard potential” rating by the EPA 

[3], and approximately one-quarter of these are located in North Carolina (the most of any 

state; Fig. 1). 

Despite the large amount of CCP wastes that are generated and disposed annually in NC, 

the risks associated with disposal practices are not well known, particularly in light of a recent 

coal ash spill at the Tennessee Valley Authority (TVA) Kingston Fossil Plant in Harriman, TN. 

On December 22, 2008, a breach in the retaining wall for the CCP storage pond resulted in the 

accidental release of approximately 4.1 million m3 of coal ash onto the surrounding land surface 

and into the adjacent Emory and Clinch Rivers [4]. This disaster was the largest coal ash spill in 

U.S. history and brought waste storage practices for CCPs to the nation’s attention [5]. 

Consequently, the EPA has recently reviewed its regulations with respect to the definition of 

CCPs and modes of its disposal [6]. In NC, an increasing public awareness has called to 

impose new regulations on storage and reuse of CCPs (e.g., Sierra Club report, [7]).

Table 1: Summary of power plant sites in NC (see location in Fig. 1), energy production, and 

updated average flow data (million gallons per day, MGD) for ash pond and cooling water 

discharges from June 2007 to June 2010. Data was provided by the Division of Water Quality, 

Surface Water Protection, North Carolina Department of Environment and Natural Resources.
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Nine coal fired plants in North Carolina (Table 1) discharge a total of 554.1 million gallon 

per day (MGD) of effluents from ash holding ponds and 4315.4 MGD of cooling water (see 

distribution in Table 1). This massive discharge has a significant impact on the hydrological

balance of the water resources associated with these outflow sites and, moreover, on their 

water quality. The objective of this project is to provide systematic water quality data for 

each of these sites. Previous data and our own preliminary measurements (see below) 

suggest that effluents that are discharged from the ash ponds have high contents of 

contaminants originated from coal ash. In addition, a larger volume of effluent is discharged 

from the coal-fired plants as cooling water (Table 1) with an assumption of higher water quality, 

but without any supported data. This project will also provide a systematic analysis of the 

quality of cooling water effluents, given the huge volume of their discharge to the water 

resources of NC.

The highest volume of ash pond effluents in NC is discharge from the Roxboro Steam 

Station (average flow of 502 MGD) into Hyco Lake (Fig. 2). A preliminary survey by the Division 

of Water Quality Surface Water Protection at the North Carolina Department of Environment 

and Natural Resources (DENR) [8] has shown that the levels of contaminants, particularly 

selenium, arsenic, thallium and boron, in the outfall (NPDES OUTFALL 003) of Roxboro Steam 

Station (NC0003425) to Hyco Lake is extremely high. From June 3, 2008 through June 2, 2009, 

fifty-three weekly samples were collected from Outfall 03. The data show that the annual 

Figure 1. Proposed sampling locations of nine surface water sites in North Carolina those 

receive direct runoff or effluent from CCP storage ponds from coal power plants.
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discharge had Se concentrations in the range of 5 to 23 ppb, mostly above 5 ppb, which is the 

EPA Criterion Continuous Concentration (CCC) for aquatic life. The As concentrations varied 

from 5 to 16 ppb relative to 10 ppb, which is Maximum Contaminant Level (MCL) for drinking 

water. Thallium (Tl) concentrations yielded a mean of 3.8 ppb (the North Carolina Water Quality 

Standard/ Environmental Protection Agency Criteria for Tl is 0.24 ppb and for Water Supply 

waters and Human Health based on fish consumption is 0.47 ppb). Boron concentrations varied 

from 500 to 1100 ppb, which is much higher as compared to typical streams and rivers in NC 

(<50 ppb) [8]. 

The DENR study from Hyco Lake also revealed high concentrations of Se and As in fish 

tissues. The median concentration of Se in the fish samples (n=21) collected in 2009 of was 2.7 

mg/kg, with 15 of 21 fish tissue sample results above the EPA Subsistence Fisherman 

Contaminant Level of 2.457 mg/Kg, and 6 of 21 were above the EPA Criteria for Wildlife 

Protection Contaminant Level of 3.0 mg/kg. For arsenic all of 44 samples had As levels above 

the EPA Recreational Fisherman concentration of 0.026 mg/kg [8].

Discharge of mercury is known to occur; however, the fate of Hg in Hyco Lake is less 

certain. Mercury differs from other contaminants (e.g., arsenic, selenium) in that this metal is a 

concern if converted to methylmercury in benthic sediments of lakes and streams and 

bioaccumulated in the food web. Mercury analyses in the DENR study [8] did not use the most 

sensitive methodology; thus, mercury was not detected in the discharge to Hyco Lake (<200 

ng/L). However, in process water effluents, Progress Energy (the operator of the Roxboro plant) 

reported concentrations up to 747 ng/L, much greater than EPA surface water guidelines (< 12 

ng /L). While mercury is released directly to Hyco Lake, significant bioaccumulation in 

recreational fish was not observed [8]. Coal ash wastes are expected to contain forms of 

mercury that are bioavailable to sediment microorganisms that methylate mercury (mainly 

sulfate-reducing bacteria). In addition, our previous work demonstrated that CCPs contain large 

quantities of leachable sulfate [5] that is capable of stimulating methylmercury production, 

particularly in freshwater settings. While mercury methylation may be active in receiving water 

sediments; food web accumulation in Hyco Lake may be confounded by excess selenium, 

which is known to counteract trophic transfer of mercury. In light of these unknowns, additional 

data on methylmercury levels in the receiving waters of CCP storage pond effluents is needed 

understand the overall risks associated with Hg in CCPs. 

3.2.1. Preliminary results from Hyco Lake, NC

As the first stage to evaluate the quality of water resources in NC that are affected by 

direct discharge of effluents from coal ash holding ponds and cooling water, we initiate a 

preliminary sampling (November 2009, February 2010, August 2010) of Hyco Lake (Fig. 1). 

Hyco Lake receives a large volume of effluents from Roxboro Steam Station (Table 1). Time 

series analysis of the three sampling campaigns reveals that the concentrations of leachable 

coal ash contaminants (LCACs) [5] such as boron vary significantly with time, showing high 

levels during relatively low lake levels (Fig. 2). These variations indicate that an assessment of 

the contribution of coal ash effluents to the water quality of surface waters in NC should 

consider both variations in the effluent composition and hydrological conditions, such as water 

level (i.e., dilution factor). 

A detailed investigation of the lake water chemistry in August 2010 indicates that the 

LCACs in Hyco Lake can be divided into two groups based on their geochemical variations: (1) 

elements that behave conservatively in the lake water (Ca, Mg, B, Se, Li, Sr, Cr) and their 

concentrations are depended on the mass balance between the coal ash effluents and pristine 

water (Fig. 3); and (2) elements that associated with the redox state of the water (As, Ba, Mn) 

and show relatively high concentrations in anoxic deep water during thermal stratification of the 

lake (Fig. 4). These results are consistent with similar trends in leachable LCACs in areas 

impacted by the TVA coal ash spill in Kingston, TN that observed in our previous investigations 
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[5]. Consequently, low redox potential at the lake 

bottom water after seasonal thermohaline 

stratification of the water column can enhance 

mobilization of trace elements that are retained 

by the lake sediments under oxic conditions. 

It should be noted that the high boron concentrations (~1000 ppb) we found in Hyco Lake is 

associated with relatively low arsenic (2-7 ppb) and selenium (1-2.5 ppb) contents. However, 

the consistent variations of As and Mn with depth and redox condition (Fig. 4) indicates that 

reductive dissolution of Mn-oxides (and possibly Fe-oxides) releases As to the bottom lake 

water. This phenomenon can explain the apparent inconsistency; low As in the lake water 

relative to high As in fish tissues from the lake [8]. We therefore propose that As enrichment and 

bioaccumulation may occur in reduced zones in affected lakes (bottom water, pore water) due 

to the sensitivity of As to redox conditions and speciation (see in Section 3.6). The notion that 

CCP storage pond impact can simply be quantified by measurements at the receiving 

water surface may not be fully appropriate. The overall impact of coal ash effluents on 

water resources will be the focus of this proposed project. We propose to investigate 

temporal (changes of hydrological conditions) and spatial (depth profile, pore water) 

Figure 2. Variation of boron concentrations as 

compared to water level (USGS data) changes in Hyco 

Lake. Note that high boron contents were recorded 

during periods of low lake levels.

Figure 3. Variations of boron and selenium versus calcium contents in Hyco Lake as 

measured during August 2010. Similar linear correlations were observed for Mg, Sr, Li, and 

Cr, which suggest that the concentrations of these elements depend on mixing 

relationships between coal ash effluents and pristine water. 
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water quality variations that will ensure a reliable assessment of this potential impact.

Finally, we measured 

the boron isotope 

composition of Hyco 

Lake. The δ11B results 

(see section 3.6 for 

explanation of the 

definition of δ11B) was -

2.4‰, which is

consistent with our 

previous research [5], 

in areas impacted by

the TVA coal ash spill 

(i.e., elevated boron 

and negative δ11B 

value). These 

observations indicate 

that boron isotopes 

may be useful as a 

tracer of oxyanions (As 

and Se) released by 

CCPs’ storage ponds.

3.3. Statement of results or benefits

The project aims to provide an assessment on the water quality status of water resources 

that are associated with long-term discharge of effluents from major CCP holding ponds and 

storage sites in NC. The study will provide a scientific evaluation for the fate of contaminants 

that are generated in CCPs holding ponds and transported into the environment. The results of 

the study will address some of the key questions related to the impact of CCPs on water 

resources in NC:

• What is the extent and magnitude of contamination of water resources in NC by long-term 

and unmonitored discharge of effluents from the major CCP holding ponds in NC?

• What is the impact of the large volume of cooling water discharged from coal fired plants 

on water resources in NC? Can we assume that cooling water has low levels of 

contaminants?

• Is mixing and dilution the key process that controls the actual contaminant concentrations 

in the affected lakes and rivers? 

• What are the other biogeochemical processes that cause differential distribution of 

contaminants in the affected water resources?

• What are the ecological and water management risks that are associated with continued 

discharge of CCP effluents to water resources in NC?

• Would changes in water availability (e.g., increased upstream use, consecutive droughts 

induced from climate change) and/or environmental conditions (e.g., rise in temperature, 

redox conditions) in the affected water resources increase the contamination risks of 

these resources?

Given that the EPA is reconsidering waste disposal requirements for CCPs (i.e., 

Figure 4. Variations of dissolved (< 0.45μm) manganese, arsenic, and 

barium concentrations with water depth at Hyco Lake during August 2010. 

The relatively enrichment of these elements with depth is associated with 

reducing conditions and thermohaline stratification of the lake water, which 

suggests that reductive dissolution of Mn-oxides and release of As to the lake 

water. 
8

reclassification as hazardous materials) and effluent discharge from CCP holding ponds might 

require much more rigorous permission procedures that includes water quality assessments, 

this project will provide DENR and other state and federal agencies the scientific basis for 

adequate monitoring tools for tracing the impact of CCP contaminants on water resources. The 

project is also designed to evaluate the changes of each of the contaminants that is associated 

with CCP’s discharge, delineate the geochemical processes that affect contaminant distribution, 

and provide a theoretical framework for predicting their abundance under different 

environmental conditions (pH, redox state, salinity).

3.4. Nature, scope, and objectives of research

This project aims to evaluate the impact of Coal Combustion Products (CCPs) on the 

quality of water resources in North Carolina by integration of existing database and generating 

additional field-based water quality data. For several decades CCPs have been stored in 

landfills and holding ponds in NC (Fig. 1) without systematic evaluation of the impact of 

leachates generated from CCPs on associated water resources. The literature and our own 

previous investigations [9-18] have shown that leachates that are generated from CCPs are 

enriched in contaminants such as arsenic, selenium, boron, strontium, thallium, and barium that 

could affect the ecological system upon migration into the environment. 

The objectives of this project are (1) determine the magnitude of contamination of 

impacted water resources in NC by effluents discharged from CCPs holding ponds and cooling 

water; (2) evaluate the fate (e.g., retardation) of key contaminants (arsenic, selenium, boron, 

strontium, barium, methylmercury) in water resources and the environmental factors that control 

these variations; (3) establish reliable monitoring tools for evaluating the impact of CCPs on NC 

water resources that can be used for state regulations; and (4) provide the scientific basis for 

possible future state regulation on CCP storage in NC.

We hypothesize that (1) the geochemical tracers we have developed in our previous 

investigation of the TVA coal ash spill in Kingston TN [4-5], which consist of trace metals 

(arsenic, selenium, boron, strontium, barium) and boron isotope composition [5, 9], are capable 

of elucidating contaminants that originate from CCPs leachates in affected water resources; and 

(2) the environmental conditions (pH, redox state) control the species distribution of oxyanions 

(arsenic, selenium, boron) [1, 10-11] and mercury [19-20] in the water and thus their reactivity 

with the host sediments (lake) or aquifer rocks (groundwater). We will test these hypotheses by 

systematic sampling of water bodies located in the vicinity of CCP storage ponds in NC (Fig. 1), 

quantification of major elements, trace-metals and boron isotopes, and modeling of species 

distribution in the investigated water. The fieldwork will include in-situ measurements (pH, 

temperature, DO, EC, redox potential) and systematic sampling of surface water and

groundwater (Fig. 1). In the lake sites, we will also collect water column, sediment and 

sediments pore water at different depths and distances from the effluent discharge areas. 

Groundwater samples will be collected from wells located both upstream and downstream from 

CCPs holding ponds. We will collect water and sediment samples using standard procedures for 

trace metal analyses. In filtered (0.45 mm) and unfiltered grab samples, we will quantify major 

and trace metals (Ca, Mg, Fe, Li, B, V, Cr, Mn, As, Co, Ni, Zn, Se, Rb, Sr, Mo, Cd, Sb, Ba, TI, 

Pb,Th, and U) by ICP-MS and major anions by ion chromatography and integrate new data with 

the existing state database of the Division of Water Quality of DENR. We will also quantify 

isotopic compositions of boron by thermal ionization mass spectrometry (TIMS). Total Hg and 

methylmercury (MeHg) concentration will be determined by atomic fluorescence spectroscopy 

using standard EPA methods. We will utilize chemical equilibrium models (e.g., MINEQL+) to 

assess aqueous phase speciation and saturation index. In particular, we will investigate how the 

species distribution of arsenic (AsV and AsIII), selenium (SeVI and Se IV), boron (B(OH)3 and 

B(OH)4

-

), and methylmercury are controlled by environmental factors (redox, pH). We will use 

boron isotopes to verify and quantify the impact of CCPs on the investigated water resources.
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We plan to perform a field sampling at each of the major sites in NC (Table 1) as the first 

stage of the research. For some sites, (e.g., Hyco lake) we will collect water samples on a 

monthly basis to monitor possible seasonal changes in both effluents and affected water 

compositions. Since we have already established our field and analytical procedures, we will be 

able to begin the research as soon as the first month of the project period. 

3.5. Methods, procedures, and facilities

We will perform systematic measurements of surface waters and groundwater associated 

with CCP holding ponds in North Carolina coal-fired plants (Figure 1, and Table 1). The EPA 

reported in a recent survey of 431 holding ponds in the nation, 49 have been assigned a “high 

hazard potential” rating, and approximately one-quarter of these are located in North Carolina 

(the most of any state). 

We propose 9 field sessions for one-year project at 9 different sites that receive effluent or 

runoff from holding ponds at coal-fired plants (Figure 1; Table 1). Fieldwork and sampling will 

be coordinated with staff of the Division of Water Quality, Surface Water Protection, 

North Carolina Department of Environment and Natural Resources (DENR). We have 

already established effective and productive working relations with DENR (see attached 

support letter), which will guarantee the successful operational and data assimilation 

that will be generated in this project.

The fieldwork will include in-situ measurements (pH, temperature, DO, EC, redox 

potential) and systematic sampling of surface water at different water depths, pore water 

extracted from lake and river sediments, sediments in lakes and rivers in the vicinity of the 

discharge areas, and groundwater in affected areas (Asheville site). In the lake sites, we will 

collect pore water and sediments with Wildco Box core (25 cm depth) and Russian Peat core 

(up to 1 meter depth) from different depths and distances from the effluent discharge areas. 

Groundwater samples will be collected from wells located both upstream and downstream from 

CCP holding ponds. We will follow standard quality assurance practices for the collection and 

analysis of water and sediment samples for trace element determination. These protocols 

including polyethylene or polycarbonate containers rinsed overnight in an acid bath followed by 

rinsing with ultrapure water. For mercury, fluoropolymer or glass containers will be used. Tracemetal grade acids will be used to preserve samples. Samples will be collected using clean 

hands protocols, stored in plastic bags, and refrigerated during transport. In the laboratory, open 

sample containers will be handled in a HEPA-filtered laminar flow hood. Sample analyses will 

be based on standard calibrations (performed daily) and verified with NIST-certified reference 

materials. The acceptance criteria for data quality will vary depending upon the type of data 

collected. In general, a relative standard deviation of less than 10% for replicate chemical 

analyses would indicate good precision. Bias (i.e., systematic error) will be determined for each 

method of analyses by method blanks, equipment blanks, and matrix spike recoveries. 

Precision will be analyzed through replicate samples and specified by the percent relative 

standard deviation. 

The effluents of holding ponds will be collected by either direct access (as we have done 

with TVA) or through sampling in the receiving water directly downstream of discharge points. In 

filtered (0.45 mm) and unfiltered grab samples, we will quantify major and trace metals by ICPMS, major cations by DCP, and major anions by ion chromatography. Total Hg concentration 

will be determined by cold vapor atomic fluorescence spectroscopy (EPA Method 1631). 

Methylmercury (MeHg) concentration in water and sediments will be determined by distillation, 

ethylation, chromatographic separation followed by atomic fluorescence spectroscopy (EPA 

method 1630) [22]. We will measure the isotopic compositions of boron (11B/10B) by thermal 

ionization mass spectrometry (TIMS) technique at Duke University.
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3.5.1. Facilities, Equipment, and Other Resources at Duke University:

1) Trace Metals, and thermal ionization mass spectrometer (Avner Vengosh)

Facilities in the Division of Earth and Ocean Sciences Division at the Nicholas School of the 

Environment at Duke includes a VG PlasmaQuad-3 inductively-coupled-plasma mass 

spectrometer (ICP-MS) equipped with the S-option pump for increased sensitivity and a UC 

laser-ablation microprobe for spot analyses to 6 microns (for ultra-trace element spot analyses 

in the ppb levels). Detection limits (defined as peak:blank ratios of 3:1) have been 

demonstrated at <1 ppt for heavier elements (mass ratio greater than 80) and <5 ppt for most 

lighter elements. The ICP-MS is capable of measurements with high precision and accuracy for 

a large range of trace metals in the ppb level. 

For boron isotope measurements a Thermo Scientific TRITON thermal ionization mass 

spectrometer (TIMS) in a dedicated facility. The TRITON is a new TIMS with the most precise 

and accurate isotope ratios for positive and negative ions. The instrument was installed in 

February 2008. 

2) Environmental Engineering Laboratory (Hsu-Kim) include the following equipment 

relevant to the proposed research:

• Leeman Labs Prism Inductively-Coupled Plasma Optical Emission Spectrometer (ICPOES) for element analysis at ppb levels or higher

• Agilent 7700 Series ICP-MS with helium collision cell capability for removal of polyatomic 

interferences during detection of trace elements at parts-per-trillion levels.

• Brooksrand MERX cold vapor atomic fluorescence spectrophotometer for total mercury 

detection at 0.5 ng/L or greater

• Milestone Direct Mercury Analyzer (for Hg in solids and sediments)

• BrooksRand distillation, purge-and-trap, cryogenic gas chromatogaph apparatus for 

methylmercury analysis in water and sediment

• Total Organic Carbon Analyzer (Shimadzhu)

• UV-Vis spectrophotometer with integrating sphere

• Varian high performance liquid chromatograph (HPLC) system with photodiode array and 

fluorescence detectors

• Two trace metal-clean HEPA-filtered laminar flow work stations

• COY anaerobic vinyl glove box

• numerous fume hoods

• Barnstead Nanopure water filtration system (>18 MΩ-cm resistivity). 

3.6. Related research

3.6.1. Introduction

Toxic elements are capable of leaching from CCPs storage locations, either through 

continuous discharge of effluents (e.g., holding ponds) or from accidental releases (e.g., TVA 

coal ash spill) that affect the quality of associated receiving waters. In some cases, however, 

contaminants are not readily leached from CCPs. Such instances depend on the type and/or 

origin (e.g., bottom versus fly ash) and composition of the CCPs, the concentration of trace 

metals in the original coal source, combustion process parameters, treatment (e.g., flue gas 

desulfurization (FGD) for removing sulfur dioxide), and environmental conditions for disposal 

(e.g., storage pond water chemistry, redox condition). CCPs generally represent a mixture of 

solid wastes from various stages of coal combustion and flue gas treatment (e.g., bottom ash, 

fly ash, boiler slag, FGD material). CCP wastes that are disposed in holding ponds and landfills 

typically consist mostly of fly ash and bottom ash [23]. 
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3.6.2. Metals and metalloids mobilization from CCPs: the dependence on species 

distribution

Numerous studies have shown that coal ash contains high levels of toxic metals and 

metalloids that can harm the environment. Some of these elements are soluble in water and 

easily extracted in aquatic systems [10, 16-17, 24-31]. Our previous investigation of the TVA 

coal ash spill in Kingston, TN [5, 9] and Hyco Lake in NC showed relatively high levels of As, 

Se, B, Ba, and Sr in water associated with CCP discharge. This proposal focuses 

particularly on evaluating the reactivity of these elements and Hg and the conditions that could 

enhance their mobilization and bioavailability in aquatic systems.

Arsenic and selenium mobilization: Mobilization of arsenic and selenium from CCPs 

and their contents in CCP leachates depend on the environmental conditions (acidity, redox, 

solids/liquids ratio, time, temperature), the chemical composition of the water medium and the 

properties of ash itself (content of metals, acidity) [11, 32]. As and Se leaching from acidic 

ashes are likely controlled by the formation of surface complexes with Fe- and Mn-oxides, while 

the leaching from alkaline ashes are controlled by the solubility of calcium coprecipitates in the 

ash [14]. Previous studies have also shown that arsenic in CCPs exist predominantly as the 

oxidized As(V) species while selenium exists as the intermediate valence Se(IV) [1, 12-13, 15, 

33]. Wang et al.[11] have shown (and we have confirmed by our preliminary leaching 

experiments) that As and Se contents in leachates vary with pH, in accordance to sorption 

trends typical for oxyanions: low and high pH conditions induce higher As and Se mobilization 

relative to neutral pH (Figure 5).

 The species distribution of As and Se leached into solution will depend not only on pH, 

but also on redox conditions. Under reducing conditions, arsenic species consist of arsenite 

(AsIII), which occurs as the uncharged species H3AsO3 at neutral pH and dissociates to H2AsO3

-

under high pH conditions (pKa=9.3). Under oxic conditions, arsenate (AsV) is composed of 

arsenic acid (H3AsO4

0

) with pKa

dissociation constants of 2.3, 6.8 and 11.3 

([1]; Figure 5). Selenium species 

distribution also depends on pH and 

redox. In reducing conditions, selenium 

occurs in natural systems as SeIV or Se0

while in oxidizing conditions selenium 

occurs as SeVI (selenate). SeVI is found as 

H2SeO3

0

, HSeO3

-

, and SeO3

2-

 with acid 

dissociation constants of 2.6 and 8.3 ( [1]; 

Figure 5). Se(0) readily forms an insoluble 

elemental Se precipitate. 

At low pH (less than pH ~2) 

uncharged H3AsO3

0

 and H2SeO3

0

 species 

are predominant (Figure 5), which results 

in high mobilization of both As and Se. 

Under near neutral pH, the charged anion 

species adsorb more strongly to mineral 

oxides; thus, their mobilization is limited. 

At high pH values, deprotonation of 

hydroxyl groups on mineral surfaces and 

increased competition from OH- ions 

results in an overall decrease in As and 

Se anion sorption. However at higher pH 

values, both AsO4

3-

 and SeO3

2-

 are 

capable of precipitating with CaFigure 5. Modeling of the distribution of arsenic, 

selenium and boron species in fresh water conditions as a 

function of pH, based on literature values [1] of the 

dissociation constants of the weak acids of arsenic, 

selenium and boron. Note the distinction between 

reduced and oxidized states of arsenic.
12

compounds (e.g., Ca-arsenate [34]), and thus, their mobilization would be dependent on the Ca 

content of the solution. Consequently, Wang et al.[11] showed that sub-bituminous coal ashes 

leached more Ca than the bituminous coal ashes, which resulted in significantly lower As and 

Se leaching from sub-bituminous coal ash. Our preliminary results confirm this phenomenon, 

particularly with the coal ash from the Duke University coal power plant. Compared to the TVA 

Kingston ash, the lime-treated Duke ash contained more leachable Ca, causing a reduction of 

dissolved As and Se at high pH leaching conditions.

Boron mobilization: Similar to As and Se, boron in aquatic solution occurs as the 

uncharged boric acid (B(OH)3

0

) and borate ion ((B(OH)4

-

), depending on solution pH (Figure 5), 

salinity, and temperature. The adsorption of boron on oxides and clay minerals show maximum 

adsorption (i.e., less leaching) in the pH range 8-9, indicating that the borate anion adsorbs 

more significantly than the uncharged boric acid species [35-38]. Under high pH conditions, high 

concentrations of hydroxide ions compete with borate ions for adsorption sites. Since the 

dissociation of boric acid depends on salinity and temperature, the relative proportion of boron 

species in the solution would affect boron mobilization from CCPs. At high pH conditions borate 

can condense onto CCP particles through the formation of ion-pairs with Na, Ca, and Mg [35-

38], resulting in removal of boron from solution and a decrease in apparent boron reactivity with 

leachates. The similarity of boron reactivity and species distribution to those of As and 

Se makes boron a unique tracer that can potentially mimic the mobilization of these 

oxyanions. In this study, we will use an approach that combines total boron content in 

leachates and boron isotope fractionation to delineate the role of species distribution on the 

mobilization of As and Se from CCPs. We will use the known dissociation constant of boric acid 

and its variation with salinity and temperature [39] to model the boron species distribution under 

the controlled experiments and predict the isotopic composition of dissolved boron in the 

leachates. These models would provide a better assessment of the reactivity of boron in the 

natural conditions and a direct evaluation of the retardation of boron and its reactivity with 

sediments or aquifer materials.

3.6.4. Fate of metals and metalloids in the environment: the role of acidity and redox 

state

CCPs are not classified as hazardous waste; thus, discharge from landfills and holding 

ponds is not always controlled or monitored. Accumulation of As, Se, B, Hg, and other metals in 

leachates originating from CCPs may therefore pose an ecological risk if the waste is improperly 

disposed of or accidentally released to the environment. Consequently, the conditions prevailing 

in holding ponds and landfills would control the reactivity of these elements and their fate in the 

environment. The literature shows that acidity and redox potential are two water chemistry 

variables that are critical to the fate of these elements. However, most hazard assessments of 

CCP waste materials only address leaching related to acidity. Much less is known concerning 

transformations induced by redox gradients. 

As shown earlier, the speciation of As, Se, B, and Hg would control the mobilization of 

these elements from CCPs and would also determine their fate in the environment. For 

example, As in CCPs occurs in the As(V) form, but could be converted to the more mobile 

As(III) form under anaerobic conditions [45] (e.g., landfill, sediments with high organic content). 

Likewise, the adsorption of Se (IV) would decrease with pH as the fraction of selenium as 

SeO3

2-

 increases[1] (Figure 2 and 3). Thus at pH>7.5, the mobility of Se (IV) in pore water is 

expected to be high, unless SeO3

2-

is precipitated into calcium selenates in the presence of high 

Ca contents in CCPs [11]. Under strongly reducing conditions such as those found in organic 

matter-rich wetland sediments, Se is often immobilized by conversion to an elemental Se(0) 

solid phase (e.g., [46]). Further reduction to Se(-II) would result in insoluble metal selenides (Feselenides, Cu-selenides, HgSe). In contrast, boron speciation would not be affected by the 

redox state, only by the pH conditions. Our preliminary results from the NSF RAPID project 
13

confirm this model. Data from pore water extracted from sediments in which ash has 

accumulated due to the TVA coal ash spill in the Clinch River, downstream from the spill area, 

show significantly high As/Se ratios relative to both laboratory experiments and surface water 

contamination in the tributary area (the Cove). The high As/Se ratios are associated with 

predominance of the reduced As(III) and low of dissolved oxygen, inferring anaerobic 

conditions. In the proposed project we will model the relationships between As, Se, and B 

species, for predicting their behaviors under given temperature, pH, and redox 

conditions.

3.6.5.Boron isotope as a tracer of CCPs

Boron has two stable isotopes (11B/10B ratio ~4), which has a large variation in nature due 

to the large fractionation of relatively light isotopes. The boron isotope ratio has been used to 

trace groundwater contaminants such as agricultural runoff, wastewater, and petroleum waste 

[47-50]. Williams and Hervig [51] studied B isotopic values of different coals in the U.S. and 

determined that 11B was highly depleted in coal compared to most terrestrial rocks. Thus, coal is 

characterized by negative δ11B values (as low as -70‰) relative to the international standard 

(δ11B is defined as [(11B/10B)sample/ (11B/10B)NIST-SRM951 -1]×1000 where the units are reported in 

per mil). Limited data on the boron isotope ratios in CCPs suggest that coal ash has δ11B values 

(ranging from -4 to-19‰) that are similar to the coal [47, 52], although the direct relationship 

between the composition of co-existing coal and CCPs, nor the mechanisms that control boron 

isotopic fractionation in CCPs, have not yet been established. The boron isotope fractionation 

depends on the distribution of boron species [53], which in turn is controlled by the salinity, 

temperature, and pH. Boric acid is enriched in 11B while the borate anion is enriched in 10B. The 

dependence of boron isotope variations on pH and salinity could be used to determine the 

conditions in which CCP leachate-derived boron interacts with sediments or aquifer rocks and 

as an indirect proxy for the mobilization of Se and As, which also depends on pH conditions.

Our leaching experiments of the TVA ash showed depleted δ11B values, in the range of -

14 to -18‰, which is consistent with results from surface water in a region of limited water 

exchange (“Cove” in Figure 4) from the TVA spill area of low δ11B values of -13‰. These 

isotope ratios are significantly different from upstream Emory River (+10 to +15‰), which 

represents meteoric boron. Slightly contaminated river water downstream from the ash spill in 

Emory and Clinch Rivers showed intermediate δ11B values of 0 to +5‰. 

These results clearly demonstrate the sensitivity of boron isotopes for tracing 

dissolved boron that is derived from CCPs leaching in aquatic systems. 

3.7.Training potential.

This project is based on the research of two graduate students from the Nicholas School 

of Environment (Laura Ruhl) and Pratt School of Engineering (Amrika Deonarine). In addition, 

we expect 2-3 more undergraduate students to be involved in this study as part of their honors 

thesis. Furthermore, the research will be the based of the course “Coal Combustion Products 

and Their Impact on the Environment: Exploration of the coal ash spill in Kingston Tennessee” 

that is given to master’s students as part of the Master of Environmental Management (MEM) at 

the Nicholas School of Environment. Students in this course will visit the proposed field sites as 

part of the class. 
14

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17

5. CVs of the investigators:

______________________________Avner Vengosh, PhD____________________________

Professor,

Nicholas School of the Environment Telephone: (919) 681-8050

Division of Earth & Ocean Sciences Fax: (919) 684-5833

Duke University E-mail: vengosh@duke.edu

Box 90227,

Durham, NC 27708-0235 _____________________________________________________________________________________________

EDUCATION

1984 B.Sc., Hebrew University of Jerusalem, Jerusalem, Israel, Geology

1986 M.Sc., Hebrew University of Jerusalem, Jerusalem, Israel, Geology

1990 Ph.D., Australian National University, Canberra, Australia, Environmental 

Geochemistry

ACADEMIC APPOINTMENTS

1991-1999 Research Scientist (Senior Lecturer), Hydrological Service, Jerusalem, Israel.

1996-1997 Visiting scientist (sabbatical leave), Institute of Earth and Marine Sciences, 

University of California, Santa Cruz, California.

1999-2005 Associate Professor, Deaprtment of Geological and Environmental Sciences, Ben 

Gurion University, Beer Sheva, Israel.

2003-2004 Visiting Professor (sabbatical leave), Department of Deaprtment of Geological and 

Environmental Sciences, Stanford University, California.

2005-2010 Associated Professor, Division of Earth and Ocean Sciences, Nicholas School of 

Environment, Duke University, Durham, North Carolina.

2009- Associated Professor (Secondary Appointment), Department of Civil and 

Environmental Engineering, Pratt School of Engineering, Duke University, 

Durham, North Carolina.

2010- Professor, Division of Earth and Ocean Sciences, Nicholas School of 

Environment, Duke University, Durham, North Carolina.

PROFESSIONAL SERVICE 

2001- 2005 Associate Editor for the international journal Water Resources Research.

2007- Associate Editor of the international journal Applied Geochemistry.

Publications

 (Vengosh’s graduate students indicated by *)

1) Ruhl, L.*, Vengosh. A., Dwyer, G.S., Hsu-Kim, H., Deonarine, A., Bergin, M., Kravchenko, J. 

(2009). Survey of the potential environmental and health impacts in the immediate 

aftermath of the coal ash spill in Kingston, Tennessee. Environmental Science and 

Technology, 43, 6326–6333.

2) Vengosh, A., Hirschfeld, D*., Vinson, D.S*., Dwyer, G.S. Raanan, H*., Rimawi, O., Al-Zoubi, 

A., Akkawi, E., Marie, A., Haquin, G., Zaarur, S., and Ganor, J. (2009) High Naturally 

Occurring Radioactivity in Fossil Groundwater in the Middle East. Environmental 

Science and Technology (DOI: 10.1021/es802969r).

3) Vinson, D.S.*, Vengosh, A., Hirschfeld, D*. and Dwyer, G.S. (2009). Relationships between 

radium and radon occurrence and hydrochemistry in fresh groundwater from fractured 

crystalline rocks, North Carolina (USA). Chemical Geology, 260, 159-171.

4) Raanan, H.*, Vengosh, A., Paytan, A., and Nishri, A. (2009) Quantifying saline groundwater 

flow into a fresh water lake using the Ra isotope quartet: A case study from the Sea of 

Galilee (Lake Kinneret), Israel. Limonology and Oceanograpghy, 54(1), 119–131.
18

5) Pratson, E., Vengosh, A., Dwyer, G., Pratson, L. and Klein, E. (2010). The Effectiveness of 

Arsenic Remediation from Groundwater in a Private Home. Ground Water Monitoring 

and Remediation, 30, 87-93.

6) Kloppmann, W., Vengosh, A. Guerrot, K., Millot, R., and Parnkaratov, I. (2008) Isotope and 

ion selectivity in reverse osmosis desalination: Geochemical tracers for man-made 

freshwater. Environmental Science and Technology, 42 (13), 4723–4731, 

10.1021/es7028894.

7) Vengosh, A., Hening, S.*, Ganor, J., Mayer, B., Weyhenmeyer, C.E., Bullen. T.D. , and 

Paytan, A. (2007). New isotopic evidence for the origin of groundwater from the Nubian 

Sandstone Aquifer in the Negev, Israel. Applied Geochemistry, 22, 1052-1073.

8) Farber, E.*, Vengosh, A., Gavrieli, I., Marie, A., Bullen, T.D., Mayer, B., Holtzman, R.*, Segal, 

M.*, and Shavit, U. (2004) The origin and mechanisms of salinization of the Lower 

Jordan River. Geochimica Cosmochimica Acta, 68, 1989-2006.

9) Vengosh, A., Kloppmann, W., Marie, A., Livshitz, Y., Gutierrez, A., Banna, M., Guerrot, C., 

Pankratov, I., Ranan, H., (2005). Sources of salinity and boron in the Gaza Strip: 

Natural contaminant flow in the southern Mediterranean Coastal aquifer. Water 

Resources Research, 41, W01013, doi:10.1029/2004WR003344.

10) Vengosh, A. (2003). Salinization and Saline Environments. In: Sherwood Lollar, B. (ed.), 

Environmental geochemistry (volume 9), Treatise in Geochemistry. Executive Editors: 

Holland, H.D. and Turekian, K.T., Elsevier Science.

SYNERGISTIC ACTIVITIES (last 3 years)

2009 Chair of the session “Future Impacts on Hydrogeological Resource Potential 

and Quality: Global Change and Implications for the Future of Water 

Resources in Arid and Semi-Arid Regions”, Goldschmidt 2009, Davos, 

Switzerland, June, 2009.

2009 Testimony to the Subcommittee on Water Resources & Environment, U.S. 

House of Representatives -Tennessee Valley Authority's Kingston Ash Slide: 

Potential Water Quality Impacts of Coal Combustion Water Storage. 

Washington DC, March 2009 

(http://transportation.house.gov/hearings/hearingDetail.aspx?NewsID=834).

2008 Keynote speakers at University Council on Water Resources/ National Insititue 

for Water Research annual conference “ International water resources: 

Challenges for the 21st century” , Durham, NC, July 2008.

2007 Chair of a special session (Pardee Keynote Symposia) of the Geological 

Society of America, entitled “Middle Eastern Water Resources in Times of 

Crisis”, 2007 GSA Annual Meeting & Exposition, Denver, October 28-31, 

2007.

2007 Chair of a session entitled “Natural Contaminants in Groundwater Resources: 

Occurrence, Geochemistry, Health, and Remediation“, American Geophysical 

Union [32], Joint Assembly Meeting, Acapulco, Mexico, May 22-25, 2007.

2007- Member of the Environment Surveillance Committee of the N.C. Radiation 

Protection Commission.

2006 Chair of a Workshop on “Radon Occurrence, Health Risks and Policy, with an 

Emphasis on Radon in Ground Water Drinking Supplies”, Duke Garnens, 

Duke University, Durham, NC, (http://www.nicholas.duke.edu/radon/), 

October 4, 2006.
19

Heileen Hsu-Kim, Ph.D. 

Assistant Professor Phone: (919) 660-5109

Duke University Fax: (919) 660-5219

Civil & Environmental Engineering E-mail: hsukim@duke.edu

127A Hudson Hall, Box 90287

Durham, NC 27708

Education and Training

Massachusetts Institute of Technology Environmental Engineering Science B.S. 1998

University of California, Berkeley Environmental Engineering M.S. 1999

University of California, Berkeley Environmental Engineering Ph.D. 2004

University of Delaware Marine Science, Post-Doctoral Fellow 2005

Research and Professional Experience

Duke University, Civil & Environmental Engineering. Assistant Professor 2005-present

University of Delaware, College of Marine Studies. Postdoctoral Fellow 2004-2005

University of California, Berkeley. Graduate Student Instructor Fall 1999

Lawrence Livermore National Laboratory, Student researcher Summer 1998, 1999

Journal Publications

1. Zhang T. and Hsu-Kim H. (2010). Photolytic degradation of methylmercury enhanced by 

binding to natural organic ligands. Nature Geoscience. 3, 473-476. DOI: 10.1038/NGEO892

2. Gondikas A.P., Jang E.K., Hsu-Kim H. (2010). Influence of amino acids cysteine and serine 

on aggregation kinetics of zinc and mercury sulfide colloids. J Coll Interf Sci. 347, 167-171.

3. Ruhl L., Dwyer G.S., Deonarine A., Hsu-Kim H., Bergin M., Kravchenko J., Vengosh A. 

(2009). Survey of the potential environmental and health impacts in the immediate aftermath 

of the coal ash spill in Kingston, Tennessee. Environ. Sci. &Technol. 43, 6323-6333.

4. Deonarine A. and Hsu-Kim H. (2009). Precipitation of mercuric sulfide nanoparticles in 

NOM-containing water: Implications for the natural environment. Environ. Sci. &Technol. 43, 

2368-2373.

5. Lau B. and Hsu-Kim H. (2008). Precipitation and growth of zinc sulfide nanoparticles in the 

presence of thiol-containing natural organic ligands. Environ. Sci. &Technol. 42, 7236-7241.

6. Hsu-Kim H. (2007). Stability of Metal-Glutathione Complexes During Oxidation by Hydrogen 

Peroxide and Cu-Catalysis. Environ. Sci. &Technol. 41, 2338-2342.

7. Hsu-Kim H., Mullaugh KM., Tsang J.J., Yucel M., Luther G.W. (2008). Formation of Zn- and 

Fe-sulfides near hydrothermal vents at the Eastern Lau Spreading Center: Implications for 

sulfide bioavailability to chemoautotrophs. Geochem. Transactions. 9:6. 

8. Tsang J.J., Rozan T.F., Hsu-Kim H., Mullaugh K.M., Luther G.W. (2006). 

Pseudopolarographic determination of Cd2+ complexation in freshwater. Environ. Sci. 

&Technol. 40, 5388-5394.

9. Hsu-Kim H. and Sedlak D.L. (2005). Similarities between inorganic sulfide and the strong 

Hg-complexing ligands in municipal wastewater effluent. Environ. Sci. &Technol. 39, 4035-

4041.

10. Hsu H. and Sedlak D.L. (2003). Strong mercury complexation in wastewater effluent and 

surface waters. Environ. Sci. &Technol. 37, 2743-2749.

Honors

National Science Foundation Ridge2K Postdoctoral Fellowship, “Metal sulfide speciation 

and cluster formation at deep-sea hydrothermal vents”, 2004

ACS Environmental Chemistry Division Graduate Student Paper Award, 2003

National Physical Science Consortium Graduate Student Fellowship, 1998-2004

UC-Berkeley Outstanding Graduate Student Instructor Award, 1999-2000
20

NSF Graduate Research Fellowship, finalist (declined for NPSC award), 1998

Synergistic Activities

• Guest co-editor for special issue of Environmental Science and Technology: Nanoscale 

NOM-Metal Interactions; publication for spring 2011

• NSF Center for Environmental Implications of NanoTechnology: Co-Investigator of 

Theme 1 (Exposure, Transport and Transformations in Laboratory Systems) and Core B 

(Natural and Incidental Nanomaterials in the Environment)

• Patterson Award Committee member (2008-2011), Geochemical Society 

• Faculty advisor for FEMMES (Females Excelling More in Math, Engineering, and 

Science): Duke education outreach program for 4th-6th grade students.

Professional Affiliations

Memberships: American Chemical Society, American Geophysical Union, Association of 

Environmental Engineering and Science Professors, Geochemical Society

Academic honor societies: Tau Beta Pi, Chi Epsilon, and Phi Beta Kappa

Teaching

CE/ENV 242 Environmental Aquatic Chemistry. (graduate level) F 2005-08, 10 

CE120L Chemical Processes in Environmental Engineering. (undergrad Sp 07-08, F08-10

CE265 Instrumental Methods of Environmental Pollutants (graduate) Sp 2008

CE265 Aquatic Geochemistry (graduate) Sp 2009-10

Collaborators (recent 48 months)

G. Aiken (USGS-Boulder), M. Auffan (CEREGE), M. Deshusses (Duke), R. DiGiulio (Duke), 

M. Hochella (Virginia Tech), J. Hower (Kentucky), T. Johnson (UIUC), J. Little (Virginia 

Tech), G. Lowry (Carnegie Mellon), A. Masion (CEREGE), T. Phelps (ORNL), J. Rose 

(CEREGE), N. Robins (NCSU), J. Ryan (CU-Boulder), M. Wiesner (Duke), A. Vengosh 

(Duke).

Current Research Advisees

Postdoctoral Scholar: Lee Bryant (2010-present)

Ph.D. Students: Amrika Deonarine (2005-present), Tong Zhang (2007-present), Andreas 

Gondikas (2008-present)

Undergraduate Student Researchers: Brian Au (CEE, 2012), Marianne Leonhardt (CEE, 

2012)

Former Research Advisees

Boris Lau (Postdoctoral Associate 2007-2008), Patrick Canning (Undergraduate researcher 

2008-09) , Natalya Polishchuk (Summer REU Researcher 2007), Eileen Jang (high school 

student, 2008-2009), Avi Agaarwaal (high school student 2010)

Former Mentors: D. Sedlak (graduate, UC Berkeley); G. Luther (postdoctoral, U. Delaware)
21

6. Other Information

6.1. Information transfer:

Assimilation of the data generated in this study will be conducted by working closely with the 

staff of the Division of Water Quality, Surface Water Protection, North Carolina Department of 

Environment and Natural Resources (DENR). We have already established effective and 

productive working relations with DENR (see attached support letter). In addition we plan to 

present the data in national and international conferences (e.g., the results of the NSFsupported project on the TVA coal ash spill were presented in nine national and international 

conferences in the USA during 2009 and 2010). We plan to present the data also to NC 

Environmental Management Commission in order to enhance discussion for possible 

legislations changes in NC concerning coal ash disposal and water monitoring. Finally, we plan 

to publish the data in professional peer-reviewed journals.

6.2. Progress review:

This is a new WRRI project.

7. Closely Related Proposals: involving the PI and/or co-PIs

Vengosh and Hsu Kim:

Agency: NSF; project: The impact of coal combustion products on the environment: 

geochemical and isotopic prospective. Budget: $336,017. This proposal seeks to evaluate the 

overall impact of coal combustion products on the environment and involves systematic 

leaching experiments of major coal ash from the USA. While the WRRI proposal seeks to 

evaluate the actual impact on water resources in NC, the NSF proposal is much more general 

and aims to evaluate the overall risks of coal ash impact on the environment and mechanisms 

of contaminants leaching from coal ash.
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8. Letters of support or collaboration
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9. Budget Justification

Graduate Student Researcher: Funds are requested to support three months salary of a 

graduate student for this project. The student will be responsible for fieldwork, lab 

measurements, and data interpretation. The compensation rate per full-time student is $25,245 

per year. Duke University Ph.D. student wages are determined by the Graduate School in 

consultation with the faculty, department heads, deans, and the University administration, based 

on consideration of living costs and the competitive market for top-quality Ph.D. students.

 Fringe Benefits: Fringe benefits at Duke are based on the fiscal year and as such they may 

differ based on the time period over which they are calculated. In accordance with Duke 

University guidelines, the fringe benefits rate for the graduate student researcher is 8.4% per 

year.

Travel: Funds in the amount of $12,000 are requested to support travel expenses for the 

student and PIs. The funds will be used to cover travel to CCP storage pond sites and 

associated water resources in NC. The travel funds will also be used to support travel for either 

the PI or graduate student to present project results at a national scientific conference (e.g., 

Goldschmidt, American Geological Society, American Geophysical Union). 

Materials, Supplies, and Consumables: Funds in the amount of $28,049 are requested to 

purchase laboratory supplies that are needed for this project. These supplies include items such 

as chemicals, glassware, sampling bottles, pipette tips, tubing, consumable parts for metals 

analyses, compressed gases, consumables for laboratory instruments, and other water and 

mineral analyses. In addition these funds include cost for ICP-MS instrument time ($35 per 

sample). We expect to collect about 100 to 150 water samples during the course of the project.

Equipment: No funds are requested for the purchase of equipment. All major equipment to be 

used for this project has already been purchased. 

Other Direct Cost: For the 2010-2011 academic year, summer Semester tuition remission for 

Ph.D. research assistants is set at $2,755 per semester ($8,265 annually). These rates are set 

by the Graduate School and are applied consistently across the University, regardless of 

funding source.