Facilitated Bioaccumulation of Perfluorooctanesulfonate in Common

Subscriber access provided by CORNELL UNIVERSITY LIBRARY

Article

Facilitated bioaccumulation of perfluorooctane sulfonate in common carp (Cyprinus carpio) by graphene oxide and remission mechanism of fulvic acid Liwen Qiang, Meng Chen, Ling-Yan Zhu, Wei Wu, and Qiang Wang Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.6b02100 • Publication Date (Web): 10 Oct 2016 Downloaded from http://pubs.acs.org on October 10, 2016

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Environmental Science & Technology is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 30

Environmental Science & Technology

1

Facilitated bioaccumulation of perfluorooctane sulfonate in common carp (Cyprinus

2

carpio) by graphene oxide and remission mechanism of fulvic acid

3

Liwen Qiang†, Meng Chen†, Lingyan Zhu ,†,‡ , Wei Wu†, Qiang Wang†

4

†College of Environmental Science and Engineering, Tianjin Key Laboratory of Environmental

5

Remediation and Pollution Control, Key Laboratory of Pollution Processes and Environmental

6

Criteria, Ministry of Education, Nankai University, Tianjin, P.R. China 300071

7

‡College of natural resources and environment, Northwest A&F University, Yangling, Shaanxi, P.R.

8

China 712100

*

9 10

∗

To whom correspondence should be addressed. E-mail: [email protected]. Phone: +86-22-23500791. Fax: +86-22-23503722. 1

ACS Paragon Plus Environment


11

ABSTRACT

12

As one of the most popular carbon-based nano-materials, graphene oxide (GO) has the potential

13

to be released in aquatic environment and interact with some coexistent organic pollutants, such as

14

perfluorooctane sulfonate (PFOS), which is an emerging persistent organic pollutant. In this study,

15

the adsorption of PFOS on GO in presence of fulvic acid (FA), the impacts of GO and FA on PFOS

16

toxicokinetics in carp (Cyprinus carpio), and in vitro digestion behaviors were examined. The results

17

indicated that PFOS could be strongly adsorbed on GO with a Freundlich affinity coefficient KF of

18

580 ± 205 (mg/g)/(mg/L)n, while the adsorption was suppressed by FA due to competitive adsorption.

19

GO significantly enhanced the bioaccumulation of PFOS in blood, kidney, liver, gill, intestine and

20

muscle of carp, and the corresponding BAF was in the range of 2 026 ~ 53 513 L/kg. The

21

enhancement was greatest for liver and intestine, which was 10.3 and 9.33 times of that without GO,

22

respectively. In vivo toxicokinetic and in vitro digestion-absorption experiments indicated that GO

23

could carry PFOS to penetrate the intestine cells. There herein, PFOS absorption, especially via

24

intestine, and the uptake rate coefficient (ku) were greatly enhanced, leading to distinctly promoted

25

bioaccumulation of PFOS in fish. However, FA could facilitate the flocculation of GO in the intestine,

26

and also accelerate excretion of GO-PFOS complex. Thus, in the presence of FA, PFOS absorption

27

was reduced and the promotion effect of GO on PFOS accumulation was remitted.

28

Keywords: graphene oxide, PFOS, fulvic acid, bioaccumulation, fish

29 30

INTRODUCTION

31

Graphene oxide (GO) is a graphene sheet with carboxylic groups at its edges and phenol

32

hydroxyl and epoxide groups on its basal plane.1 Due to its excellent water dispersion and 2


Page 2 of 30

Page 3 of 30


33

amphiphilic characteristics,2 it has found wide applications in energy storage, catalysis, cell imaging,

34

biochemical sensing, drug delivery and pollutant remediation.3 Although the production volume of

35

GO is less than some metallic nanomaterials, such as nano-TiO2,4 nano-Ag,5 it is now considered to

36

be a potential emerging environmental pollutant, and its adverse effects on aquatic organisms have

37

received increasing attentions.6 Many studies documented that GO could interact with cells and

38

bacteria via specific interactions, and produced some toxicological effects (including genotoxicity

39

and cytotoxicity).7-10 Studies on biodistribution of GO in mice/rat demonstrated that GO was prone

40

to accumulate in liver, lungs and spleen through intravenous injection.11-14 Giving that GO has

41

abundant π-π electrons and surface carboxylic, phenol hydroxylic groups, it could adsorb a variety of

42

pollutants, such as organic molecules (phenanthrene, tetracycline),15, 16 inorganic metal ions (Pb2+,

43

Cd2+),17, 18 macromolecules (DNA, humic acid)19, 20 and particles (single-walled carbon nanotubes),21

44

forming GO-associated complexes in aquatic environment.

45

As an emerging persistent organic pollutant (POP), perfluorooctane sulfonate (PFOS) has been

46

recognized as a global contaminant and widely present in humans, wildlives and waters all over the

47

world.22 It is extremely persistent in the environment and shows toxicities on mammals and fish.23, 24

48

Owing to the hydrophobic carbon chain and hydrophilic sulfonate functional group,25 PFOS could be

49

adsorbed by a variety of adsorbents,25 such as multiwalled carbon nanotubes26 and carbon nitride.27 It

50

is assumed that PFOS may also be adsorbed on GO to form GO-PFOS complex given that GO has

51

abundant surface groups. In our previous study, it was found that nano-TiO2 could promote PFOS

52

accumulation in fish by carrying PFOS into intestine and promote PFOS absorption. But TiO2 could

53

not be accumulated in fish tissues since the aggregated nano-TiO2 particles were too large to

54

penetrate the cell membranes.28 Considering that GO was distinctly different from nano-TiO2 in 3



Page 4 of 30

55

chemico-physical properties, it is hypothesized that GO may affect PFOS bioavailability and

56

bioaccumulation via special mechanisms.

57

Natural organic matter (NOM) is widely present in aquatic environment

29

and it could affect 29-32

58

the fate and transport as well as bioavailabilities and toxicities of co-exist contaminants.

For

59

example, NOM might reduce the toxicities of co-exist AgNPs in Shewanella oneidensis MR-1 33 and

60

Daphnia,32 GO in zebrafish embryogenesis,34 but enhance the toxicity of TiO2 in developing

61

zebrafish.35 Humic substances are complex organic molecules that represent the largest constituent of

62

NOM, while fulvic acid (FA) is an important constituent of humic substances, which is soluble in

63

water under all pH conditions.36 It has many O-containing functional groups such as hydroxyl,

64

carboxyl and phenolic groups,37 and is able to interact with a variety of organic and inorganic

65

compounds.

66

The objectives of the present study were to investigate: 1) adsorption and desorption of PFOS

67

on GO and the influence of FA on these processes; 2) impacts of GO on uptake and elimination of

68

PFOS in fish tissues with/without FA; 3) absorption behaviors of PFOS and GO using an in vitro

69

digestion and absorption model. The results are beneficial to assess the impacts of engineered GO on

70

the environmental behaviors of organic pollutants in natural aquatic environment.

71

MATERIALS AND METHODS

72

Chemicals and Reagents

73

Potassium perfluorooctane sulfonate (PFOS, 98%), and sodium perfluoro-1-[1, 2, 3,

74

4-13C4]octanesulfonate (MPFOS, 99%) were purchased from Wellington Laboratories (Guelph, ON,

75

Canada). The stock solution of PFOS was prepared at 500 mg/L in Milli-Q water, and stored at 4 ℃.

76

Graphene oxide nanoplates (GO) (> 99%) was purchased from Nano Materials Tech Co. (Tianjin, 4


Page 5 of 30


77

China). Fulvic acid (FA) (> 90%) was purchased from Aladdin Chemistry Co. Ltd. (Shanghai, China).

78

Pepsin (from porcine gastric mucosa lyophilized powder, 3 200 ~ 4 500 U/mg protein), pancreatin

79

(from porcine pancreas > 7 500 U/mg), sodium taurocholate and sodium glycodeoxycholate were

80

purchased from Sigma Chemical Co. (Sigma-Aldrich China Ltd., Shanghai, China). All of the

81

solvents used for chromatography were of high-performance liquid chromatography (HPLC) grade.

82

Milli-Q water was used for the sample pretreatment.

83

Preparation and Characterization of GO and FA

84

Based on the information provided by the supplier, GO was synthesized using a modified

85

Hummers method.38 A stock suspension of GO (300 mg/L) was prepared by sonicating 0.3 g of GO

86

powder in 1 000 mL Milli-Q water for 4 h. The obtained stock suspension was stored in dark at 4 ℃.

87

The hydrodynamic size of GO nanoplates was measured by dynamic light scattering (Zetasizer

88

nano-ZS90, Malvern Instruments, United Kingdom) and was in the range of 246 ~ 257 nm. The

89

representative transmission electron microscope (TEM) images (JEM-2 100, JEOL, Tokyo, Japan)

90

and field emission scanning electron microscopy images (FE-SEM, LEO, 1530 vp, Germany) of GO

91

are shown in Figure 1 a, b, c. The thickness of the GO material, which was 0.7 ~ 1.8 nm, was

92

determined by atomic force microscopy imaging (AFM, Santa Barbara, CA) (Figure 1 d). The

93

surface C/O atomic ratio was determined as 2.14 with an X-ray photoelectron spectroscopy (PHI 5

94

400 ESCA System). The Brunauer-Emmer-Teller (BET, Micromertics ASAP 2010 Accelerated

95

Surface Area and Poresimetry System, Micromeritics Instrument Corporation) surface area was

96

measured as 208.6 m2/g. The Raman spectra (Renishew in Via Raman spectrometer, RM2 000, UK)

97

is shown in Figure 1 e (the 2 D/G intensity ratio further indicated that the product consisted of more

98

than one layer of nanosheets);39 and the Fourier transform infrared (FTIR) transmission spectrum 5



99

(110 Bruker TENSOR 27 apparatus, Bruker Optics Inc., Germany) is shown in Figure 1 f. The FA

100

stock solution was prepared by dissolving 200 mg of FA in 1 L of Milli-Q water, which was stirred

101

for 6 h, and centrifuged at 2 739 g for 1 h. The supernatant solution was filtered through a 0.45 µm

102

membrane to remove particulates. The obtained FA stock solution was measured with a total organic

103

carbon analyzer (TOC-VCSN, Shimadzu, Japan) and it contained 80.3 ± 5.5 mg of C/L (n=3). The

104

FTIR spectrum of obtained FA is shown in Figure S1 a, and was characterized by X-ray

105

photoelectron spectroscopy to contain 77.56% C 1s, 19.53% O 1s, and 2.91% Na 1s. The result is

106

shown in Figure S1 b.

107

Experimental Design

108

Exposure tests were conducted in a series of 12 L of glass aquariums (the diameter was 20 cm,

109

height was 40 cm, water depth was 30 cm). To ensure accurate analysis of PFOS in different tissues,

110

three-month old juvenile common carp (Cyprinus carpio) were chosen for the experiment. They

111

were about 10 cm in length and 8.68 ~ 11.5 g in weight, and obtained from a local fish market. The

112

fish were acclimated in aerated and dechlorinated tap water (pH 7.1 ~ 7.5) at 25 ± 1℃ (14:10 h

113

light/dark photoperiod) for at least one month and were fed with fish feed twice a day.

114

A certain amount of PFOS, GO or FA stock solutions were added in the aquariums with 9 L

115

water and dispersed with ultrasonication and mechanical stirring for 30 min. The aquariums were

116

lightly aerated (Oxygen aeration pump ACO-002, 35 W, 40 L/min) throughout the experiment.

117

Filtered dechlorinated water with a hardness of 98.0 ± 2.6 mg/L CaCO3, pH of 7.1 ± 0.3, dissolved

118

oxygen of 7.9 ± 0.2 mg/L, was maintained at 25 ± 1 °C. The nominal PFOS concentration in all test

119

groups was 500 ng/L, except for the control group in which PFOS, GO and FA were not added. The

120

concentrations of PFOS and FA were set to be as close as possible to potential environmental levels 6


Page 6 of 30

Page 7 of 30


40, 41

121

near source area.

For GO, its concentration was set to be as lower as possible, meanwhile

122

ensuring operability and accuracy in experimental tests. Five exposure groups were designed: (1)

123

Blank group (no PFOS, GO, or FA); (2) PF group (PFOS and 2 mg C/L FA); (3) P group (PFOS only,

124

without GO or FA); (4) PG group (PFOS and 1 mg/L GO); (5) PFG group (PFOS, 2 mg C/L FA and

125

1 mg/L GO). The exposure lasted for 28 days. One aquarium in each group was sacrificed and four

126

fish were sampled on the day of 0, 1, 2, 6, 10, 16, 22, and 28 (Figure S2). At the end of exposure, all

127

the remaining fish were taken out and transferred to clean aquariums with dechlorinated tap water for

128

depuration, which lasted for another 54 days. Four fish were sampled on the day of 29, 30, 34, 38, 44,

129

50, 56, 62, and 82 for each group. The exposure solution or clean water was completely renewed

130

every two days. To minimize the influence of fish feed, fishes were fed in clean water when the

131

solution was renewed. Upon sampling, the fish were anesthetized with tricaine methanesulfonate

132

(MS-222). It was reported that PFOS was prone to accumulated in blood, liver, kidney and gill,22

133

while intestine is one of the major uptake routes for pollutants. Thus blood was immediately taken

134

from the fish. Subsequently the fish were dissected for liver, kidney, intestine, gill and muscle, which

135

were homogenized separately. At each sampling time, 200 mL of water was sampled from the middle

136

of the aquariums. The fish samples were stored at −54 °C, and the water samples were stored at 4 °C

137

until pretreatment.

138

Simulated Gastric and Intestinal Digestion Model

139

Preparation of digestive fluids. The simulated digestive fluids were prepared on a daily basis as

140

described in the United States Pharmacopeia with minor modifications.42 The simulated gastric

141

control fluid (SGFc) contained 2 mg/mL NaCl in Milli-Q water (pH 2.0). The simulated gastric fluid

142

(SGF) was prepared by mixing pepsin with the SGFc (stored at 4 ℃) to achieve a concentration of 4 7



143

mg/mL. The simulated intestinal control solution (SIFc) (pH 6.8) was composed of 6.8 mg/mL of

144

KH2PO4 and 0.616 mg/ mL of NaOH in Milli-Q water. The simulated intestinal fluid (SIF) consisted

145

of 10 mg/mL pancreatin in SIFc while the simulated bile solution (SBS) consisted of 4 mM sodium

146

taurocholate and 4 mM sodium glycodeoxycholate in SIFc.

147

Simulated Gastric Digestion. Two mL of solution of the P, PF, PG, or PFG group (the mixture of

148

PG or PFG group was allowed to reach sorption equilibrium before the in vitro experiment) was

149

incubated with SGFc (25 mL) in a 50 mL polypropylene (PP) centrifuge tube (50 mL, CNW, China)

150

for 10 min at 37℃ in a shaking water bath (Crystal Technology & Industries, Inc. USA). The

151

solution was brought to pH 2.0 ± 0.1 with 1 M HCl, and topped up to 29 mL with SGFc. Freshly

152

prepared 5 mL of SGF was added, and the mixture was subsequently incubated in a shaking water

153

bath (167 rpm) at 37℃ for 2 h. The gastric digestion was terminated by adding 1 M NaOH solution

154

to adjust the solution pH to 6.8, at which the pepsin was inactivated.

155

Simulated Intestinal Digestion. The dynamic model described by Marambe et al. was used in

156

this study.43 In this model, a dialysis bag made of Spectra/Por dialysis membrane (flat width, 45 mm;

157

diameter, 29 mm) was used to simulate an intestinal compartment, based on the gastric

158

small-intestinal model (TIM-1).

159

membrane was 5 KDa. The volume of the gastric digest (pH 6.8) was adjusted to 35 mL using SIFc

160

and transferred to the dialysis bag. One mL of bile solution and 4 mL of SIF containing pancreatin,

161

previously maintained at 37 ℃, were added, and digestion continued for 0, 0.5, 1, 2, 4 and 6 h with

162

continuous stirring, respectively. In this setup, the dialysis bag was immersed in a buffer (similar in

163

composition to SIFc pH 6.8, 1 000 mL) which was maintained at 37℃. The buffer was replenished at

164

a delivering rate of 1.6 mL/min using a peristaltic pump (Baoding Longer Precision Pump Co., Ltd.

44-46

The molecular weight cutoff (MWCO) of the dialysis

8


Page 8 of 30

Page 9 of 30


165

China), and it carried the dialysed products to a receiving flask. At the end of digestion, the buffer in

166

the receiving flask and surrounding the dialysis bag was combined and labeled as dialysate. The

167

mixture remaining in the dialysis bag was collected in a 50 mL PP centrifuge tube and centrifuged at

168

10 956 g for 10 min at 4 °C. The supernatant was labeled as retentate A, while the precipitate was

169

labeled as retentate B.

170

Analysis of PFOS and GO

171

All the samples were pretreated for PFOS and GO analysis. The information about sample

172

pretreatment and analyses of PFOS and GO in the samples are provided in Supporting Information

173

(SI).

174

Batch Adsorption-Desorption Experiments

175

Sorption and desorption of PFOS on GO with/without FA were conducted. The details about the

176

sorption and desorption experiments are provided in SI.

177

Data Analysis

178 179 180

In the sorption experiments, the mass of PFOS adsorbed on GO could be calculated using the following equation: =

0 − ×

(1)

181

where, qe is the mass of PFOS adsorbed on GO (mg/g), C0 and Ce are PFOS concentrations in the

182

aqueous phase at the beginning and end of adsorption experiment (mg/L), V is the volume of the

183

solution (40 ml), and m is the mass of GO particles (g).

184 185 186

For desorption experiment, the mass of desorbed PFOS can be calculated as follows: ∆ =

×

(2)

where, ∆ is the mass of PFOS desorbed from GO (mg/g), C1 is PFOS concentration in the 9



Page 10 of 30

187

aqueous phase at the end of the desorption step (mg/L), and r is the fraction of supernatant replaced

188

at desorption, which was 0.75 in this study. Freundlich isotherm model is commonly used and usually applied to describe PFOS

189 190

adsorption.26

191

=

192

Where, KF [(mg/g) / (mg/L) n] is the Freundlich affinity coefficient, which denotes the adsorption

193

capacity, and n (unitless) is the Freundlich linearity index.47, 48 The bioaccessibility of PFOS (%PFOS) is defined as the fraction of PFOS present in the

194 195

(3)

dialysate in the in vitro model. It was calculated using the following equation.49, 50 %PFOS =

196

!"#$%"&'()*+ &,&"#'()*+

×100

(4)

The elimination rate constant (ke) of PFOS in fish was calculated by fitting the depuration data

197 198

to a first-order decay model using a nonlinear regression technique provided by Origin V 8.5 (Origin

199

Lab, USA), = .=0 −/.

200

(5)

201

Where Ce and Ct=0 are the concentrations of PFOS in the fish (ng/g ww) at time t and the beginning

202

of depuration, and ke is the elimination rate constant (1/d).51

203

The uptake rate constant (ku) was estimated by fitting the uptake data to a first-order

204

bioaccumulation model using an interactive nonlinear regression technique provided by Origin V

205

8.5.

206

=

/0 1 1 − −/ . /

207

Where Ce is the concentration of PFOS in the fish at time t (ng/g ww), Cs is the free PFOS

208

concentration in water (ng/L), and ku is the uptake rate coefficient (L/Kg/d). 10


(6)

Page 11 of 30


Depuration half-life (t1/2) was calculated using the following equation,

209

.1/2 =

210

(7)

After ku and ke were obtained, kinetic bioaccumulation factor (BAF, L/kg) was estimated as

211 212

52 /

ku/ke.22

213

For PFOS concentrations in fish, they were expressed as the mean values of four replicates and

214

standard deviation. One-way analysis of variance (ANOVA) was used to compare the differences

215

between groups, and the differences were considered statistically significant when p was 0.05) in fish body weight was observed during the experimental period. In the

254

P group, the uptake and depuration kinetics of PFOS in the fish tissues are shown in Figure 2. PFOS

255

concentrations in various tissues increased with exposure time, up to maximum on day 28. The

256

PFOS concentrations in the fish tissues followed the order of: blood > kidney > liver > gill >

257

intestine > muscle, which was in agreement with previous studies.22 The PFOS concentrations

258

decreased exponentially in the depuration process. The bioaccumulation parameters were calculated

259

and are shown in Table 1. The calculated BAFs of PFOS in the fish tissues were in the range of 900 ~

260

16 623 L/kg. The large BAFs in blood, kidney and liver were related to the high uptake rates in these

261

tissues. The half-life was in the range of 19.2 ~ 34.9 d, and the half-life in the liver and blood was

262

longer than that reported in rainbow trout,22 which could be due to different fish species.

263

In the presence of GO, the measured total PFOS concentration in water was similar to the P

264

group (Figure S5 a), while the dissolved PFOS concentration in PG group was much lower than that

265

of P group (p liver > kidney >

271

intestine > gill > muscle, which was different from that in P group. Gill absorption is an important

272

uptake route for dissolved toxicants to enter blood by passive diffusion through the lamellar

273

blood-water interface of gill. 22, 58, 59 As shown in Table 1, the uptake rate constant (ku) of PFOS in

274

gill in PG group was 2.88 times of that in P group. This was in agreement with the results studied by 13



275

Zielińska et al, who reported that the rate of the solid/water partition equilibration of diclofenac was

276

enhanced in the presence of sorbing nanoparticles.60 However, the kus of PFOS in liver, blood and

277

intestine in the PG group were more promoted, which were 10.3, 3.64 and 9.33 times of those in P

278

group. This suggested that apart from absorption via gills, PFOS was also greatly taken-up by

279

intestine in the form of GO-PFOS complexes. This hypothesis was testified by the large amount of

280

black GO residue in intestine, which will be discussed later. As a result, PFOS entered enterohepatic

281

recirculation in fish, whereby it was continuously recycled between blood, liver, and intestine.22 It is

282

worth noting that the greatest facilitation of ku mainly happened in the liver and intestine. Previous

283

studies using mice as model animal via tail vein injection demonstrated most GO mainly located in

284

liver and other reticuloendothelial system.11, 12, 14 The results suggested that GO might carry PFOS

285

and circulate from intestine to liver and blood, leading to promoted accumulation of PFOS in these

286

tissues.

287

In the PF group, the dissolved PFOS level was similar to that of P group, suggesting that there

288

was no significant interaction between them. As a consequence, the BAFs of PFOS in fish tissues

289

(except in kidney) were similar to the P group, implying that FA alone did not distinctly affect PFOS

290

accumulation. In the PFG group, the dissolved PFOS in water column was slightly lower than P

291

group, but higher than PG group (Figure S5). This was explained by the alleviated adsorption of

292

PFOS on GO in the presence of FA. The PFOS concentration in the fish tissues in the PFG group

293

was lower than the PG group during the uptake period, and in some tissues, such as in blood,

294

intestine, and muscle, was even lower than the P group (Figure 2). This suggested that FA inhibited

295

PFOS accumulation in fish in the presence of GO. Similar phenomena was reported in previous

296

studies, which demonstrated that HA could reduce the toxicities of co-exist pollutants.33, 34 As shown 14


Page 14 of 30

Page 15 of 30


297

in Table 1, the ku of PFOS in the PFG group was significantly lower than that in PG group, but

298

similar to that in P group. Similarly, the BAFs in the PFG group were also lower than those in PG but

299

similar to P group. These results suggested that PFOS accumulation in fish was highly related to the

300

uptake routes of PFOS.

301

In Vitro Simulated Digestion and Absorption Behaviors

302

As reported in our previous study,28 nano-TiO2 promoted accumulation of PFOS in fish by

303

acting as a vehicle of PFOS. However, nano-TiO2 is prone to aggregate and precipitate in water, and

304

it could not be absorbed in fish but depurated from fish directly. The greater promotion effect of GO

305

on PFOS accumulation could be related to its better absorption and stronger binding ability to PFOS

306

than nano-TiO2. An in vitro digestion test was conducted to understand the absorption of PFOS in the

307

presence of GO and FA, and the PFOS profiles in the different groups are shown in Figure 3. The

308

PFOS profile in the dialysate increased gradually, while decreased in the retentates over time in all

309

groups. The %PFOS was 69.7, 70.3%, 84.4, and 54.4% in P, PF, PG, and PFG group after 6 h

310

digestion, respectively. In the PF group, FA itself did not affect PFOS bioaccessibility in digestive

311

system (Figure S7), which well explained the negligible effect of single FA on PFOS

312

bioaccumulation in fish. In the presence of GO, %PFOS was facilitated to a greater extent compared

313

with P group. It was reported that the monolayer or a few-layer GO sheets were able to cut and

314

penetrate the membranes by the sharp edges.6, 34 The sharp zigzag edges of GO are visible in Figure

315

1b. Thus, GO acted vehicle to carry more PFOS into dialysate giving that GO could adsorb PFOS

316

strongly. In order to further illustrate the effect of GO in digestion process, absorptivity of GO in

317

different groups was also assessed. As shown in Figure 4, the absorptivity of GO increased with

318

digestion time, which could reach 45.8 ± 1.8 % in 6 h. These results indicated that GO might 15



319

penetrate cell membranes and circulate in body fluid. As a consequence, PFOS accumulation in fish

320

tissues was promoted.

321

In the presence of FA, %PFOS was lower than the P and PG groups. As shown in Figure S4, FA

322

modified the surface of GO and made the edges of GO sheets become much blunter and thicker,

323

agreeing with the hydrodynamic size, which was 253 and 386 nm in PG and PFG group, respectively.

324

In addition, serious aggregation of GO was observed in PFG group in the digestion process (Figure

325

S8). Most GO flocculated in the presence of FA in digestive system, which could happen in fish

326

intestine. As a consequence, it became hard for GO to penetrate the membranes, leading to reduced

327

bioaccessibility of PFOS in intestine. Hence, the %PFOS in PFG was lower than that in P and PG

328

groups.

329

Based on the in vitro experiment, the great facilitation effect of GO on PFOS accumulation in

330

fish was correlated to the great uptake rate and facilitated absorption of PFOS by GO in intestine. On

331

the other hand, FA suppressed the bioavailability of GO and PFOS, leading to reduced accumulation

332

of PFOS in fish in the presence of FA.

333

Uptake Mechanism of PFOS in Fish

334

To further explore the contribution of uptake routes, including gill absorption and ingestion of

335

GO, to PFOS accumulation, concentration ratios of PFOS in gill and blood (G/B ratio), and intestine

336

and blood (I/B ratio) during the uptake period were calculated and the results are presented in Figure

337

5. In P group, it was obvious that G/B and I/B ratios increased with exposure time and achieved the

338

maximum on day 28. G/B was always higher than I/B ratio during the uptake period, indicating that

339

gill absorption made greater contribution to the total uptake of PFOS by fish. In the presence of GO,

340

both I/B and G/B were higher than the P group, suggesting that uptakes by gill and intestine were all 16


Page 16 of 30

Page 17 of 30


341

promoted. Fish takes up free PFOS via gill absorption. In addition, GO binding with PFOS might be

342

absorbed via gill and promoted PFOS absorption. However, the GO sheets were very flexible and

343

may flat out on the gill surface, thus occupying absorption sites

344

exposure time went on. Thus, after 16 d, the G/B ratio decreased. During the whole exposure period,

345

I/B was close or higher than G/B and increased all the time. This suggested that ingestion of GO and

346

the following absorption via intestine made more contribution to blood accumulation of PFOS than

347

gill.

30

and blocking passages in gill as

348

Some black residues adhering to the intestine wall were observed even after purging for one

349

week in PG group, suggesting that GO could interact with the cellular membranes intensely. Since

350

GO is amphiphilic, it could easily pass through phospholipid bilayer.61 Therefore, it is potential for

351

GO which carried PFOS to adsorb on the intestine wall for a longer time and even pass through cell

352

membranes, leading to enhanced assimilation of PFOS by intestine wall.

353

In occurrence of FA, G/B and I/B were lower than those in PG group, especially for I/B, even

354

lower than P group. This implied that the remission effect of FA was mainly due to the suppression of

355

PFOS absorption via intestine. It was reported that NOM could facilitate graphene elimination in

356

Daphnia magna.62 Unlike P group, the SEMs of feces in PG and PFG groups showed apparent sheet

357

and corrugation structure, indicating large amount of GO was depurated in the feces (Figure S9).

358

Figure 6 illustrates the color of the fish feces in PG and PFG groups during the depuration period. It

359

is clear that GO was depurated from fish much faster in the presence of FA. Thus, the residence time

360

of GO-PFOS in intestine was much shorter, leading to less absorption of PFOS in the presence of FA.

361

As shown in Figure S9, PFOS level in feces was the highest in PFG group, suggesting that FA acted

362

as a lubricant and reduced adherence of GO on intestine wall, then facilitated the excretion of PFOS. 17



363

ASSOCIATED CONTENTS

364

Supporting Information

365

Details of sample pretreatment, analysis of PFOS and GO, batch adsorption-desorption

366

experiments, experiment design, characterization of FA, PFOS concentration in water column, BAFs

367

of PFOS in fish tissues, PFOS profile and experimental phenomena in vitro digestion model, SEM

368

images and PFOS concentration in feces. This material can be found in the online version.

369

ACKNOWLEDGMENTS

370

We acknowledge financial support from Ministry of Science and Technology (2014CB932001),

371

the Natural Science Foundation of China (NSFC 21325730, 21577067, 21277077), Ministry of

372

Education (20130031130005), the Ministry of Education innovation team (IRT 13024) and Yangtze

373

River scholar program.

374

375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393

(1) Liu, S. B.; Hu, M.; Zeng, T. H.; Wu, R.; Jiang, R. R.; Wei, J.; Wang, L.; Kong, J.; Chen, Y. Lateral

REFERENCES dimension-dependent antibacterial activity of graphene oxide sheets. Langmuir. 2012, 28 (33), 12364-12372.

(2) Li, D.; Kaner, R. B. Graphene-based materials. Science. 2008, 320, 1170-1171. (3) Park, S.; An, J. H.; Jung, I. W.; Piner, R. D.; An, S. J.; Li, X. S.; Velamakanni, A.; Ruoff, R. S. Colloidal suspensions of highly reduced graphene oxide in a wide variety of organic solvents. Nano Lett. 2009, 9 (4), 1593-1597. (4) Menard, A.; Drobne, D.; Jemec, A. Ecotoxicity of nanosized TiO2. Review of in vivo data. Environ. Pollut. 2011, 159 (3), 677-684. (5) Jang, M. H.; Kim, W. K.; Lee, S. K.; Henry, T. B.; Park, J. W. Uptake, tissue distribution, and depuration of total silver in common carp (cyprinus carpio) after aqueous exposure to silver nanoparticles. Environ. Sci. Technol. 2014, 48 (19), 11568-74. (6) Zhao, J.; Wang, Z. Y.; White, J. C.; Xing, B. S. Graphene in the aquatic environment: Adsorption, dispersion, toxicity and transformation. Environ. Sci. Technol. 2014, 48 (17), 9995-10009. (7) Akhavan, O.; Ghaderi, E. Toxicity of graphene and graphene oxide nanowalls against bacteria. ACS Nano. 2010, 4 (10), 5731-5736. (8) Liu, S. B.; Zeng, T. H.; Hofmann, M.; Burcombe, E.; Wei, J.; Jiang, R. R.; Kong, J.; Chen, Y. Antibacterial activity of graphite, graphite oxide, graphene oxide, and reduced graphene oxide: Membrane and oxidative stress. ACS Nano. 2011, 5 (9), 6971-6980. (9) Duch, M. C.; Budinger, G. R. S.; Liang, Y. T.; Soberanes, S.; Urich, D.; Chiarella, S. E.; Campochiaro, L. A.; Gonzalez, A.; Chandel, N. S.; Hersam, M. C.; Mutlu, G. M. Minimizing oxidation and stable nanoscale 18


Page 18 of 30

Page 19 of 30

394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437


dispersion improves the biocompatibility of graphene in the lung. Nano Lett. 2011, 11 (12), 5201-5207. (10) Hu, X.; Ouyang, S.; Mu, L.; An, J.; Zhou, Q. Effects of graphene oxide and oxidized carbon nanotubes on the cellular division, microstructure, uptake, oxidative stress, and metabolic profiles. Environ. Sci. Technol. 2015, 49 (18), 10825-33. (11) Li, Z.; Geng, Y. X.; Zhang, X. Y.; Qi, W.; Fan, Q. H.; Li, Y.; Jiao, Z. X.; Wang, J. J.; Tang, Y. Q.; Duan, X. J.; Wu, W. S. Biodistribution of co-exposure to multi-walled carbon nanotubes and graphene oxide nanoplatelets radiotracers. J. Nanopart. Res. 2011, 13 (7), 2939-2947. (12) Wang, K.; Ruan, J.; Song, H.; Zhang, J. L.; Wo, Y.; Guo, S. W.; Cui, D. X. Biocompatibility of graphene oxide. Nanoscale Res. Lett. 2011, 6. (13) Yang, K.; Wan, J. M.; Zhang, S. A.; Zhang, Y. J.; Lee, S. T.; Liu, Z. A. In vivo pharmacokinetics, long-term biodistribution, and toxicology of pegylated graphene in mice. ACS Nano. 2011, 5 (1), 516-522. (14) Zhang, X. Y.; Yin, J. L.; Peng, C.; Hu, W. Q.; Zhu, Z. Y.; Li, W. X.; Fan, C. H.; Huang, Q. Distribution and biocompatibility studies of graphene oxide in mice after intravenous administration. Carbon. 2011, 49 (3), 986-995. (15) Apul, O. G.; Wang, Q.; Zhou, Y.; Karanfil, T. Adsorption of aromatic organic contaminants by graphene nanosheets: Comparison with carbon nanotubes and activated carbon. Water Res. 2013, 47 (4), 1648-1654. (16) Gao, Y.; Li, Y.; Zhang, L.; Huang, H.; Hu, J. J.; Shah, S. M.; Su, X. G. Adsorption and removal of tetracycline antibiotics from aqueous solution by graphene oxide. J. Colloid Interface Sci. 2012, 368, 540-546. (17) Zhao, G. X.; Li, J. X.; Ren, X. M.; Chen, C. L.; Wang, X. K. Few-layered graphene oxide nanosheets as superior sorbents for heavy metal ion pollution management. Environ. Sci. Technol. 2011, 45 (24), 10454-10462. (18) Madadrang, C. J.; Kim, H. Y.; Gao, G. H.; Wang, N.; Zhu, J.; Feng, H.; Gorring, M.; Kasner, M. L.; Hou, S. F. Adsorption behavior of EDTA-graphene oxide for pb (II) removal. ACS Appl. Mater Inter. 2012, 4 (3), 1186-1193. (19) Liu, J. W. Adsorption of DNA onto gold nanoparticles and graphene oxide: Surface science and applications. Phys. Chem. Chem. Phys. 2012, 14 (30), 10485-10496. (20) Yang, Z.; Yan, H.; Yang, H.; Li, H. B.; Li, A. M.; Cheng, R. S. Flocculation performance and mechanism of graphene oxide for removal of various contaminants from water. Water Res. 2013, 47 (9), 3037-3046. (21) Qiu, L.; Yang, X. W.; Gou, X. L.; Yang, W. R.; Ma, Z. F.; Wallace, G. G.; Li, D. Dispersing carbon nanotubes with graphene oxide in water and synergistic effects between graphene derivatives. Chem-Eur. J. 2010, 16 (35), 10653-10658. (22) Martin, J. W.; Mabury, S. A.; Solomon, K. R.; Muir, D. C. G. Bioconcentration and tissue distrubution of perfluorinated acids in rainbow trout (oncorhynchus mykiss). Environ. Toxicol. Chem. 2003, 22 (1), 196–204. (23) Bogdanska, J.; Borg, D.; Sundstrom, M.; Bergstrom, U.; Halldin, K.; Abedi-Valugerdi, M.; Bergman, A.; Nelson, B.; Depierre, J.; Nobel, S. Tissue distribution of S-35-labelled perfluorooctane sulfonate in adult mice after oral exposure to a low environmentally relevant dose or a high experimental dose. Toxicology. 2011, 284 (1-3), 54-62. (24) Ji, K.; Kim, Y.; Oh, S.; Ahn, B.; Jo, H.; Choi, K. Toxicity of perfluorooctane sulfonic acid and perfluorooctanoic acid on freshwater macroinvertebrates (daphnia magna and moina macrocopa) and fish (oryzias latipes). Environ. Toxicol. Chem. 2008, 27 (10), 2159-2168. (25) Du, Z. W.; Deng, S. B.; Bei, Y.; Huang, Q.; Wang, B.; Huang, J.; Yu, G. Adsorption behavior and mechanism of perfluorinated compounds on various adsorbents-a review. J. Hazard. Mater. 2014, 274, 443-454. (26) Li, X. N.; Chen, S.; Quan, X.; Zhang, Y. B. Enhanced adsorption of PFOA and PFOS on multiwalled carbon nanotubes under electrochemical assistance. Environ. Sci. Technol. 2011, 45 (19), 8498-8505. (27) Yan, T. T.; Chen, H.; Jiang, F.; Wang, X. Adsorption of perfluorooctane sulfonate and perfluorooctanoic acid on 19



438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481

magnetic mesoporous carbon nitride. J. Chem. Eng. Data. 2014, 59 (2), 508-515. (28) Qiang, L.; Pan, X.; Zhu, L.; Fang, S.; Tian, S. Effects of nano-TiO2 on perfluorooctanesulfonate bioaccumulation in fishes living in different water layers: Implications for enhanced risk of perfluorooctanesulfonate. Nanotoxicology. 2016, 10 (4), 471-479. (29) Galvez, F.; Donini, A.; Playle, R. C.; Smith, D. S.; O'donnell, M. J.; Wood, C. M. A matter of potential concern: Natural organic matter alters the electrical properties of fish gills. Environ. Sci. Technol. 2008, 42 (24), 9385-9390. (30) Qiao, P.; Farrell, A. P. Influence of dissolved humic acid on hydrophobic chemical uptake in juvenile rainbow trout. Comp. Biochem. Phys. C. 2002, 133 (4), 575-585. (31) Kamunde, C.; Macphail, R. Effect of humic acid during concurrent chronic waterborne exposure of rainbow trout (oncorhynchus mykiss) to copper, cadmium and zinc. Ecotoxicol. and environ. saf. 2011, 74 (3), 259-269. (32) Gao, J.; Powers, K.; Wang, Y.; Zhou, H. Y.; Roberts, S. M.; Moudgil, B. M.; Koopman, B.; Barber, D. S. Influence of suwannee river humic acid on particle properties and toxicity of silver nanoparticles. Chemosphere. 2012, 89 (1), 96-101. (33) Gunsolus, I. L.; Mousavi, M. P. S.; Hussein, K.; Buhlmann, P.; Haynes, C. L. Effects of humic and fulvic acids on silver nanoparticle stability, dissolution, and toxicity. Environ. Sci. Technol. 2015, 49 (13), 8078-8086. (34) Chen, Y. M.; Ren, C. X.; Ouyang, S. H.; Hu, X. G.; Zhou, Q. X. Mitigation in multiple effects of graphene oxide toxicity in zebrafish embryogenesis driven by humic acid. Environ. Sci. Technol. 2015, 49 (16), 10147-10154. (35) Yang, S. P.; Bar-Ilan, O.; Peterson, R. E.; Heideman, W.; Hamers, R. J.; Pedersen, J. A. Influence of humic acid on titanium dioxide nanoparticle toxicity to developing zebrafish. Environ. Sci. Technol. 2013, 47 (9), 4718-4725. (36) Uwamariya, V.; Petrusevski, B.; Slokar, Y. M.; Aubry, C.; Lens, P. N. L.; Amy, G. L. Effect of fulvic acid on adsorptive removal of Cr(VI) and As(V) from groundwater by iron oxide-based adsorbents. Water Air Soil Poll. 2015, 226 (6). (37) Schepetkin, I. A.; Khlebnikov, A. I.; Ah, S. Y.; Woo, S. B.; Jeong, C. S.; Klubachuk, O. N.; Kwon, B. S. Characterization and biological activities of humic substances from mumie. J. Agr. Food Chem. 2003, 51 (18), 5245-5254. (38) Becerril, H. A.; Mao, J.; Liu, Z.; Stoltenberg, R. M.; Bao, Z.; Chen, Y. Evaluation of solution-processed reduced graphene oxide films as transparent conductors. ACS Nano. 2008, 2 (3), 463-470. (39) Calizo, I.; Balandin, A. A.; Bao, W.; Miao, F.; Lau, C. N. Temperature dependence of the raman spectra of graphene and graphene multilayers. Nano Lett. 2007, 7 (9), 2645-2649. (40) Pan, G.; You, C. Sediment-water distribution of perfluorooctane sulfonate (PFOS) in yangtze river estuary. Environ. Pollut. 2010, 158 (5), 1363-1367. (41) Da Costa, S. T.; Gressler, L. T.; Sutili, F. J.; Loebens, L.; Lazzari, R.; Baldisserotto, B. Effect of humic acid on survival, ionoregulation and hematology of the silver catfish, rhamdia quelen (siluriformes: Heptapteridae), exposed to different phs. Zoologia-Curitiba. 2015, 32 (3), 215-224. (42) Bravo, R. USP NF (united states pharmacopeia 32/national formulary 27). 2009, United Book Press, Baltimore, Maryland. (43) Marambe, H. K.; Shand, P. J.; Wanasundara, J. P. D. Release of angiotensin I-converting enzyme inhibitory peptides from flaxseed (Linum usitatissimum L.) protein under simulated gastrointestinal digestion. J. Agr. Food Chem. 2011, 59 (17), 9596-9604. (44) Bel-Rhlid, R.; Page-Zoerkler, N.; Fumeaux, R.; Ho-Dac, T.; Chuat, J. Y.; Sauvageat, J. L.; Raab, T. Hydrolysis of chicoric and caftaric acids with esterases and lactobacillus johnsonii in vitro and in a gastrointestinal model. J. Agr. Food Chem. 2012, 60 (36), 9236-9241. (45) Chen, L.; Hebrard, G.; Beyssac, E.; Denis, S.; Subirade, M. In vitro study of the release properties of soy-zein 20


Page 20 of 30

Page 21 of 30

482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521


protein microspheres with a dynamic artificial digestive system. J. Agr. Food Chem. 2010, 58 (17), 9861-9867. (46) Salovaara, S.; Alminger, M. L.; Eklund-Jonsson, C.; Andlid, T.; Sandberg, A. S. Prolonged transit time through the stomach and small intestine improves iron dialyzability and uptake in vitro. J. Agr. Food Chem. 2003, 51 (17), 5131-5136. (47) Yang, K.; Xing, B. S. Sorption of phenanthrene by humic acid-coated nanosized TiO2 and ZnO. Environ. Sci. Technol. 2009, 43 (6), 1845-1851. (48) Wang, F.; Wang, F.; Zhu, D.; Chen, W. Effects of sulfide reduction on adsorption affinities of colloidal graphene oxide nanoparticles for phenanthrene and 1-naphthol. Environ. Pollut. 2015, 196, 371-378. (49) Yu, Y. X.; Han, S.; Zhang, D.; Van De Wiele, T.; Lu, M.; Wang, D. Q.; Yu, Z. Q.; Wu, M. H.; Sheng, G. Y.; Fu, J. A. Factors affecting the bioaccessibility of polybrominated diphenylethers in an in vitro digestion model. J. Agr. Food Chem. 2009, 57 (1), 133-139. (50) Kang, Y.; Man, Y. B.; Cheung, K. C.; Wong, M. H. Risk assessment of human exposure to bioaccessible phthalate esters via indoor dust around the pearl river delta. Environ. Sci. Technol. 2012, 46 (15), 8422-8430. (51) Chen, M.; Qian, L.; Pan, X.; Fang, S.; Han, Y.; Zhu, L. In vivo and in vitro isomer-specific biotransformation of perfluorooctane sulfonamide in common carp (cyprinus carpio). Environ. Sci. Technol. 2015. 49 (23),

13817-13824. (52) Qiang, L.; Shi, X.; Pan, X.; Zhu, L.; Chen, M.; Han, Y. Facilitated bioaccumulation of perfluorooctanesulfonate in zebrafish by nano-TiO2 in two crystalline phases. Environ. pollut. 2015, 206, 644-51. (53) Chandra, V.; Park, J.; Chun, Y.; Lee, J. W.; Hwang, I. C.; Ks, K. Water dispersible magnetite-reduced graphene oxide composites for arsenic removal. ACS Nano. 2010, 4 (7), 3979-3986. (54) Deng, S.; Zhang, Q.; Nie, Y.; Wei, H.; Wang, B.; Huang, J.; Yu, G.; Xing, B. Sorption mechanisms of perfluorinated compounds on carbon nanotubes. Environ. Pollut. 2012, 168, 138-144. (55) Hartono, T.; Wang, S.; Ma, Q.; Zhu, Z. Layer structured graphite oxide as a novel adsorbent for humic acid removal from aqueous solution. J. Colloid Interface Sci. 2009, 333 (1), 114-119. (56) Zhang, X.; Kah, M.; Jonker, M. T. O.; Hofmann, T. Dispersion state and humic acids concentration-dependent sorption of pyrene to carbon nanotubes. Environ. Sci. Technol. 2012, 46 (13), 7166-7173. (57) Deng, S. B.; Bei, Y.; Lu, X. Y.; Du, Z. W.; Wang, B.; Wang, Y. J.; Huang, J.; Yu, G. Effect of co-existing organic compounds on adsorption of perfluorinated compounds onto carbon nanotubes. Front Env. Sci. Eng. 2015, 9 (5), 784-792. (58) Martin, J. W.; Mabury, S. A.; Solomon, K. R.; Muir, D. C. G. Dietary accumulation of perfluorinated acids in juvenile rainbow trout (oncorhynchus mykiss). Environ. Toxicol. Chem. 2003, 22 (1), 189–195. (59) McKim, J.; Schmeider, P.; Veith, G. Absorption dynamics of organic chemical transport across trout gills as related to octanol-water partition coefficient. Toxicol. Appl. Pharmacol. 1985, 77, 1–10. (60) Zielińska, K.; Leeuwen, H. P. V.; Thibault, S.; Town, R. M. Speciation analysis of aqueous nanoparticulate diclofenac complexes by solid-phase microextraction. Langmuir. 2012, 28, 14672-14680. (61) Kim, J.; Cote, L. J.; Kim, F.; Yuan, W.; Shull, K. R.; Huang, J. X. Graphene oxide sheets at interfaces. J. Amer.Che. Soc. 2010, 132 (23), 8180-8186. (62) Guo, X. K.; Dong, S. P.; Petersen, E. J.; Gao, S. X.; Huang, Q. G.; Mao, L. Biological uptake and depuration of radio-labeled graphene by daphnia magna. Environ. Sci. Technol. 2013, 47 (21), 12524-12531.

21



522 523 524

Page 22 of 30

Table 1 Uptake rate (ku), elimination rate (ke), half-life (t1/2) and dynamic bioaccumulation factors of PFOS in fish tissues in different groups Tissues

ke (1/d)

Rke2

BAF (L/kg)

ku (L/Kg/d)

Rku2

Half-life (d)

492±34 168±31 191±27 228±84 106±16 19.8±1.7

0.976 0.940 0.934 0.893 0.901 0.964

23.4±2.2 19.2±2.8 31.6±3.9 34.3±3.4 34.9±5.9 31.4±4.6

1793±270 1568±307 1961±388 613±125 305±23 36.1±1.8

0.904 0.918 0.909 0.945 0.919 0.907

20.7±2.5 11.4±0.5 18.4±2.1 34.7±4.7 43.8±4.0 38.9±4.4

260±137 250±60 322±87 243±32 87.6±24.7 23.3±6.1

0.816 0.869 0.932 0.995 0.962 0.886

50.9±4.1 10.7±1.8 25.0±1.8 31.7±3.3 76.4±4.2 28.3±2.4

P group

Blood Intestine Liver Kidney Gill Muscle

0.0296±0.0028 0.0360±0.0037 0.0219±0.0033 0.0202±0.0034 0.0199±0.0038 0.0220±0.0022

0.635 0.921 0.824 0.786 0.761 0.906

16623±1168 4671±867 8715±1246 11292±4147 5349±794 900±76 PG group


0.0335±0.0029 0.0608±0.0030 0.0377±0.0030 0.0200±0.0004 0.0158±0.0022 0.0178±0.0014

0.936 0.979 0.964 0.692 0.747 0.943

53513±8072 26082±5049 51983±10284 30712±6268 19308±1434 2026±102 PFG group


0.0136±0.0026 0.0650±0.0032 0.0277±0.0014 0.0219±0.003 0.00907±0.00324 0.0245±0.0027

0.766 0.901 0.980 0.814 0.410 0.856

19137±10063 3846±932 11650±3134 11134±1486 9666±2720 953±251

525 526

22


Page 23 of 30


527

Figure Captions:

528

Figure 1 Characterization of GO. a) TEM image of GO in lower magnification, b) TEM image of GO

529

in higher magnification, c) SEM image of GO, d) AFM image of GO, e) Raman spectra of

530

GO, f) FTIR spectra of GO

531

Figure 2 PFOS concentration in fish tissues during uptake and depuration phases. a) blood, b) liver, c)

532

kidney, d) muscle, e) gill, f) intestine. Each data point represents the mean concentration of

533

the quadruplicate (n=4). The error bar represents standard deviation for four replicates (n=4)

534

Figure 3 PFOS profile of dialysate, retentate A and retentate B in different groups. a) PFOS profile in

535

P group, b) PFOS profile in PG group, c) PFOS profile in PFG group

536

Figure 4 Absorptivity rate of GO in the digestion model of different groups

537

Figure 5 The concentration ratios of PFOS in gill or intestine and blood (G/B or I/B) during the

538

uptake period in different groups. The error bar represents the standard deviation for four

539

replicates (n=4)

540

Figure 6 Pictures of fish feces in PG and PFG groups in depuration period

23



541 542 543 544

Figure 1

24


Page 24 of 30

Page 25 of 30


545 546 547 548

Figure 2

25



549 550 551 552

Figure 3

26


Page 26 of 30

Page 27 of 30


553

554 555

Figure 4

556

27



557 558 559

Figure 5

28


Page 28 of 30

Page 29 of 30


560

561 562 563

Figure 6

564

29



565 566

TOC/Abstract art

567 568 569

30


Page 30 of 30

Facilitated Bioaccumulation of Perfluorooctanesulfonate in Common

Recommend Documents