Impacts of Atmospheric Mercury Deposition on Human Multimedia

Aug 31, 2016 - Impacts of Atmospheric Mercury Deposition on Human Multimedia ... The Monte Carlo technique was used to propagate the variability ...
1 downloads 0 Views 1MB Size
Subscriber access provided by CORNELL UNIVERSITY LIBRARY

Article

Impacts of Atmospheric Mercury Deposition on Human Multimedia Exposure: Projection from Observation in the Pearl River Delta Region, South China Minjuan HUANG, Sixin Deng, Hanying Dong, Wei Dai, Jiongming Pang, and Xuemei Wang Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.6b00514 • Publication Date (Web): 31 Aug 2016 Downloaded from http://pubs.acs.org on September 6, 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 31

Environmental Science & Technology

Impacts of Atmospheric Mercury Deposition on Human Multimedia Exposure: Projection from Observations in the Pearl River Delta Region, South China Minjuan Huang 2, Sixin Deng

2,3

, Hanying Dong

2,3

, Wei Dai

2,3

, Jiongming Pang2,

Xuemei Wang 1 *

1. School of Atmospheric Science, Sun Yat-sen University, Guangzhou, 510275, PR China

2. School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, PR China

3. Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, PR China

*Corresponding author e-mail: [email protected]

1

ACS Paragon Plus Environment

Environmental Science & Technology

1

Abstract: A preliminary projection was performed to determine human multimedia exposure

2

to mercury (Hg) based on deposition flux observations and to identify the impacts of

3

atmospheric Hg deposition in Pearl River Delta (PRD) region, South China. The Monte-Carlo

4

technique was used to propagate the variability throughout the projection. The regional

5

specific probability density functions (PDFs) of the studied parameters were regressed from

6

the provincial/national published data, except when the data were deficient. The atmospheric

7

Hg deposition flux ranged from 112.60 to 321.19 µg/m2/year and did not significantly

8

contribute to Hg accumulation in the regional topsoil, freshwater bodies and most food items

9

except fish. The consumption of fish and milk/dairy products was the major contributor to the

10

total exposure for adults (>18 years)/6- to 12- year children and 0- to 6- year children

11

respectively. The projected concentrations and exposure levels were the results combining

12

MeHg and inorganic Hg (Hg2+). Under the 30-year projection, the probability of risks caused

13

by Hg deposition (combining Hg2+ and MeHg) was the highest for 0- to 6- year children,

14

followed by 6- to 12- year children and adults. The ground effects driven by precipitation had

15

a significantly greater effect relative to the mass transport effects in this region.

16 17

Keywords: atmospheric deposition, mercury, flux monitoring, multimedia, human exposure,

18

Monte-Carlo technique

2

ACS Paragon Plus Environment

Page 2 of 31

Page 3 of 31

Environmental Science & Technology

19

INTRODUCTION

20

Mercury (Hg) is a potent neurotoxin of significant ecological and public health concern,

21

and it occurs in the atmosphere as vaporous elemental mercury (Hg0), vaporous divalent

22

mercury (Hg2+) and particulate mercury (HgP). Hg0 emissions generally enter the global cycle

23

because of its long residence times in the atmosphere (0.5-1.5 years). The relatively shorter

24

atmospheric lifetimes of Hg2+ (hours to days) and HgP (hours to weeks) indicate that they are

25

deposited close to their emission points 1. Deposition represents a unique pathway for the

26

vertical transportation of atmospheric Hg to the ground; subsequently, the settled Hg

27

accumulate in surface soils and water bodies, where they are methylated and magnified

28

within organisms; finally, atmospheric Hg bio-transfers to the human body through two ways:

29

(1) food chain and (2) contact with contaminated soil and water 2.

30

China is one of the largest Hg emitters in the world and accounts for approximately 30%

31

of the anthropogenic global Hg emissions (1960 tons) based on inventories recorded in 2010 3,

32

4

33

emission contributors in China; the Hg emissions primarily occur within the Pearl River

34

Delta (PRD) region 5. The PRD region is one of the largest metropolitan regions in China and

35

has experienced dramatically rapid development and urbanization in recent decades. Based

36

on the 2008 emission inventory, the anthropogenic Hg emissions in the PRD region are

37

estimated as 17,244 kg 6. Numerous studies have found that Hg emitters (such as metal

38

smelting and chlor-alkali industries) contribute to Hg contamination of the topsoil, surface

39

water and crops in their surrounding environments

40

level in the regional surface water, river sediment and estuarine sediment are indicated

. Guangdong (GD) Province is located in South China and is ranked as one of top 10 Hg

7-9

. In the PRD region, the elevated Hg

3

ACS Paragon Plus Environment

Environmental Science & Technology

41

predominantly attributed to industrial and urban sources 10-13.Therefore, Guangdong Province

42

and the PRD region in particular might be suffering from unidentified environmental impacts

43

and human health risks related to the significant regional anthropogenic Hg emissions.

44

Previous studies that evaluated multimedia exposure to emitted pollutants have

45

generally been conducted using a series of deterministic models, including emission models,

46

dispersion and deposition models, environmental media accumulation models and human

47

exposure models

48

Hg emitted from a municipal solid waste (MSW) gasification plant, compared with inhalation,

49

soil ingestion and dermal adsorption from soil 15. However, it did not consider the deposition

50

resulting water Hg load and bio-magnification in fish, although fish consumption has been

51

widely considered as an important exposure source of Hg for human 17. Morisset et al. (2013)

52

also attempted to achieve a comprehensive risk assessment of Hg for French infants and

53

toddlers by evaluation of multimedia exposure

54

sources (e.g., deposition, waste water eluent and sludge discharge) for Hg accumulation in

55

the environmental media. The current study performs a preliminary evaluation of the human

56

multimedia exposure to Hg caused by atmospheric deposition in the PRD region using

57

simplified versions of the empirical models developed by the U.S. Environmental Protection

58

Agency (USEPA) 19. Briefly, observational Hg deposition fluxes are incorporated rather than

59

simulated results from emission models, dispersion and deposition models. To differentiate

60

among the impacts of atmospheric deposition and other surface contamination sources (e.g.,

61

waste water effluent and sludge discharge), the Hg levels in the topsoil, water bodies and

62

food items were projected in the present study solely based on regional atmospheric

14-16

. Vegetable diet was reported as a major exposure pathway (>80%) of

18

. However, it could not distinguish the

4

ACS Paragon Plus Environment

Page 4 of 31

Page 5 of 31

Environmental Science & Technology

19

63

deposition fluxes. According to the empirical models established by the USEPA

,

64

atmospheric depositions influence the ground environment through vertical mass transport

65

and ground effects driven by precipitation. In this study, the impacts of these factors on

66

human exposure were identified and discussed according to the background soil levels and

67

urbanization process using a preservative exposure scenario, which assumes that (a) the study

68

population (adults >18 years and children between 0-12 years) were native; (b) all of the local

69

residentially consumed food items (grains, vegetables, fruits, meats, eggs, milk/dairy

70

products, freshwater fish) and drinking water were grown, produced and supplied within the

71

study area; and (c) all of the residents' water recreation activities occurred in an outdoor

72

natural freshwater body (e.g., rivers and lakes). The human Hg exposure pathways related to

73

atmospheric deposition included accidental ingestion of and dermal contact with soil and

74

surface water during recreation, drinking water consumption, and dietary intake.

75

In summary, the present study aims to (1) project the accumulation of Hg in

76

environmental media through observations of depositional flux, (2) evaluate the aggregate

77

multimedia human exposure and provide a comprehensive human health risk assessment

78

related to deposition for the native residents in the PRD region, and (3) identify the impacts

79

of deposition on human exposure and the roles played by precipitation and vertical mass

80

transport.

81 82

MATERIALS AND METHODS

83

Monitoring Atmospheric Hg Deposition Fluxes

84

Mercury emissions in the PRD region are located primarily in the central area (e.g., 5

ACS Paragon Plus Environment

Environmental Science & Technology

85

Guangzhou, Foshan and Dongguan) rather than in the east or west (SI Figure S1). In the

86

present study, the Guangzhou urban site (representing an area with abundant Hg emissions)

87

and the Dinghushan Natural Reserve site (representing an area with relatively low emissions)

88

were selected as two representative monitoring sites.

89

A total of 415 deposition samples were collected at the Guangzhou urban site (115 wet

90

deposition and 63 dry deposition) and the Dinghushan Natural Reserve site (166 wet

91

deposition and 71 dry deposition) continuously from Jan. 2010 to Dec. 2012 (SI Figure S1)

92

using automated wet-dry samplers (Tianhong Instrument Factory, China, ASP-2), a water

93

surface sampler. The sampler was equipped with a movable polyethylene cover that

94

alternately covered the dry or wet deposition sampling dish and was regulated by a rain

95

sensor

96

deposition samples consisted of an aggregate collected over 15 days. The dish for dry

97

deposition sampling was filled with Milli-Q water to maintain a water depth of approximately

98

2.5 cm manually

99

with 10% HCl solution and Milli-Q water for 3 times respectively. The blank for the sampler

100

was collected from the lastly rinsing Milli-Q water. The total Hg in both wet and dry

101

deposition samples was preserved by the addition of aliquots of concentrated HNO3 and

102

AuCl3

103

spectrometry (AFS-820, Beijing Jitian Instruments Co., Ltd, China), with a detection limit of

104

0.002 µg/l. The QA/QC data are summarized in Supporting Information. All of the

105

experimental performance indices in this study fell into the range of quality control

106

acceptance criteria of EPA Method 163122. Information on precipitation time and amount of

20

. The wet deposition samples were collected after rain events, whereas the dry

21

20

. Prior to sampling each time, the water surface containers were rinsed

and determined using a double channel hydride generation atomic fluorescence

6

ACS Paragon Plus Environment

Page 6 of 31

Page 7 of 31

Environmental Science & Technology

107

rainfall

at

both

sites

during

sampling

were

provided

by

the

108

Dinghushan Forest Ecosystem Research Station, CAS and Sun Yat-sen University Resource

109

Platform of Atmosphere and Environmental Science. The annual recovery rates for the rain

110

collections ranged from 78.1% to 86.1%.

111

The deposition fluxes were calculated using Eqs. 1 and 2, where Dw and Dd represent the

112

wet and dry deposition fluxes (µg/m2) respectively, R is the annual rainfall (mm), T is the

113

annual period without rainfall (h), ri is the recorded rainfall specific to each wet deposition

114

sample (mm), tj is the sampling period for each dry deposition sample (h), Hj is the water

115

depth specific to each dry deposition sample (cm), Ci/Cj is the Hg concentration in the

116

wet/dry deposition samples (µg/l), n is the number of wet deposition samples, and m is the

117

number of dry deposition samples.  =

 ∑   × 10 ∑ 

Equation 1

118

 =

 ∑

   × 10 ∑



Equation 2

119 120 121 122

Evaluation of Human Multimedia Exposure In this study, environmental media accumulation models established by the USEPA

19

123

were employed to project the Hg accumulation in the topsoil, surface freshwater bodies and

124

food items. These models are a set of box models that predict the steady-state mass of Hg

125

accumulated in the ground environment resulting from air emissions. The observational

126

results for the Hg deposition fluxes rather than the simulated results from a Hg emission 7

ACS Paragon Plus Environment

Environmental Science & Technology

Page 8 of 31

127

model and dispersion and deposition model were employed to simplify the environmental

128

media accumulation estimate. Detailed information on the associated equations is provided in

129

the Supporting Information (SI) (SI Eqs. S1-S7, SI Eqs. S13-S25, SI Tables S1 and S2, SI

130

Figure S2). In order to investigate the soil effects driven by precipitation, the “with soil

131

background” and “without” scenarios were respectively projected in the current study.

132

The human non-dietary ingestion and dermal adsorption of Hg via soil and surface water

133

during outdoor recreation were estimated according to the accumulation of Hg in

134

environmental media using SI Eqs. S8-S11 23, 24. Exposure via drinking water and food items

135

was estimated based on SI Eq. S12 23. The parameters in SI Eqs. S8-S12 are described in SI

136

Table S1. All of the processes related to plant, livestock/poultry and human exposure to Hg0

137

were not considered in the present study.

138

All of the parameters employed in the models and their references are summarized in SI

139

Table S2 and S3. To project the environmental impacts and human exposure as accurately as

140

possible, the probability density functions (PDFs) of the model parameters (related to the

141

meteorological/hydrological conditions, soil characteristics, land-use information, plant

142

growth information and exposure factors) were achieved by fitting the probability

143

distributions to the available regional data from the Web of China Met. Data Services

144

the Agriculture Statistical Yearbook of Guangdong

145

Resources 28, the China Soil Scientific Database 29, the Survey of National Land Use 30, the

146

Ministry of Agriculture of the PRC

147

Factors Handbook of Chinese Population

148

food consumption rates for 0- to 6-year children and certain hydrological and empirical data)

31

25, 26

,

27

, the Bulletin of Guangdong Water

, the China Statistical Yearbook

32

and the Exposure

33

. However, some regional deficient data (e.g.,

8

ACS Paragon Plus Environment

Page 9 of 31

149

Environmental Science & Technology

were not included.

150

The Monte-Carlo technique was applied to propagate and integrate the variability

151

throughout the environmental media accumulation models 19 and human exposure models 23,

152

24, 34

in the present study.

153 154

RESULTS AND DISCUSSION

155

The projections of environmental accumulation and human exposure in the current study

156

considered the process of Hg methylation. As the MeHg % in total Hg contained in both

157

settled dust and rainfall are very low (1) caused by Hg2+ and MeHg respectively. .

477

23

ACS Paragon Plus Environment

Environmental Science & Technology

478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521

References 1.

Zhang, L.; Wang, S. X.; Wu, Q. R.; Wang, F. Y.; Lin, C. J.; Zhang, L. M.; Hui, M. L.; Hao, J. M., Mercury

transformation and speciation in flue gases from anthropogenic emission sources: a critical review. Atmos. Chem. Phys. Discuss. 2015, 15, (22), 32889-32929. 2.

USEPA Human health risk assessment protocol for hazardous waste combustion facilities (HHRAP: Chapter

2); Office of Solid Waste and Emergency Response, U.S. Environmental Protection Agency: 2005. 3.

UNEP Global mercury assessment 2013: Sources, emission, release and environmental transport; United

Nations Environment Programme: Geneva, 2013. 4.

Wang, S.; Zhang, L.; Wang, L.; Wu, Q.; Wang, F.; Hao, J., A review of atmospheric mercury emissions,

pollution and control in China. Frontiers of Environmental Science and Engineering 2014, 8, (5), 631-649. 5.

Zhang, L.; Wang, S.; Wang, L.; Wu, Y.; Duan, L.; Wu, Q.; Wang, F.; Yang, M.; Yang, H.; Hao, J., Updated

Emission Inventories for Speciated Atmospheric Mercury from Anthropogenic Sources in China. Environmental science & technology 2015, 49, (5), 3185-3194. 6.

Zheng, J.; Ou, J.; Mo, Z.; Yin, S., Mercury emission inventory and its spatial characteristics in the Pearl River

Delta region, China. Science of the Total Environment 2011. 7.

Feng, X.; Li, G.; Qiu, G., A preliminary study on mercury contamination to the environment from artisanal

zinc smelting using indigenous methods in Hezhang county, Guizhou, China—Part 1: mercury emission from zinc smelting and its influences on the surface waters. Atmospheric Environment 2004, 38, (36), 6223-6230. 8.

Li, Z.; Feng, X.; Li, G.; Bi, X.; Sun, G.; Zhu, J.; Qin, H.; Wang, J., Mercury and other metal and metalloid soil

contamination near a Pb/Zn smelter in east Hunan province, China. Applied Geochemistry 2011, 26, (2), 160-166. 9.

Zheng, N.; Liu, J.; Wang, Q.; Liang, Z., Mercury contamination due to zinc smelting and chlor-alkali

production in NE China. Applied Geochemistry 2011, 26, (2), 188-193. 10. Shi, J.; Ip, C. C. M.; Zhang, G.; Jiang, G.; Li, X., Mercury profiles in sediments of the Pearl River Estuary and the surrounding coastal area of South China. Environmental Pollution 2010, 158, (5), 1974-1979. 11. Liu, J.; Feng, X.; Yin, R.; Zhu, W.; Li, Z., Mercury distributions and mercury isotope signatures in sediments of Dongjiang, the Pearl River Delta, China. Chemical Geology 2011, 287, (1), 81-89. 12. Liu, J.; Feng, X.; Zhu, W.; Zhang, X.; Yin, R., Spatial distribution and speciation of mercury and methyl mercury in the surface water of East River (Dongjiang) tributary of Pearl River Delta, South China. Environmental Science and Pollution Research 2011, 19, (1), 105-112. 13. Yin, R.; Feng, X.; Chen, B.; Zhang, J.; Wang, W.; Li, X., Identifying the Sources and Processes of Mercury in Subtropical Estuarine and Ocean Sediments Using Hg Isotopic Composition. Environmental Science & Technology 2015. 14. Lonati, G.; Zanoni, F., Probabilistic health risk assessment of carcinogenic emissions from a MSW gasification plant. Environment International 2012, 44, 80-91. 15. Lonati, G.; Zanoni, F., Monte-Carlo human health risk assessment of mercury emissions from a MSW gasification plant. Waste Management 2013, 33, (2), 347-355. 16. USEPA Mercury study report to congress (Volume III); Office of Air Quality Planning and Standards and Office of Research and Development, U.S. Enivrionmental Protection Agency: 1997. 17. Shao, D.; Kang, Y.; Cheng, Z.; Wang, H.; Huang, M.; Wu, S.; Chen, K.; Wong, M. H., Hair mercury levels and food consumption in residents from the Pearl River Delta: South China. Food chemistry 2013, 136, (2), 682-688. 18. Morisset, T.; Ramirez-Martinez, A.; Wesolek, N.; Roudot, A.-C., Probabilistic mercury multimedia exposure assessment in small children and risk assessment. Environment international 2013, 59, 431-441. 19. USEPA Human health risk assessment protocol for hazardous waste combustion facilities (HHRAP: Chapter 24

ACS Paragon Plus Environment

Page 24 of 31

Page 25 of 31

522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565

Environmental Science & Technology

5); Office of Solid Waste and Emergency Response, U.S. Environmental Protection Agency: 2005. 20. Wang, X.; Wu, Z.; Shao, M.; Fang, Y.; Zhang, L.; Chen, F.; Chan, P.-W.; Fan, Q.; Wang, Q.; Zhu, S., Atmospheric nitrogen deposition to forest and estuary environments in the Pearl River Delta region, southern China. Tellus B 2013, 65. 21. Allibone, J.; Fatemian, E.; Walker, P., Determination of mercury in potable water by ICP-MS using gold as a stabilising agent. Journal of Analytical Atomic Spectrometry 1999, 14, (2), 235-239. 22. USEPA Method 1631, Revision E: Mercury in Water by Oxidation, Purge and Trap, and Cold Vapor Atomic Fluorescence Spectrometry; Office of Water, United States Environmental Protection Agency: Washington, D.C., 2002. 23. USEPA Risk assessment guidance for superfund volume i: Human health evaluation manual (Part A); Office of Emergency and Remedial Response, U.S. Environmental Protection Agency: Washington, D.C.: 1989. 24. USEPA Risk assessment guidance for superfund volume i: Human health evaluation manual (part e, supplemental guidance for dermal risk assessment); Office of Superfund Remediation and Technology Innovation, U.S. Environmental Protection Agency: Washington, D.C., 2004. 25. NSTI, Guangdong Monthly Meteorologial DataSet http://www.escience.gov.cn/metdata/page/index.html. In China Met. Data Service. 26. NSTI,

China

Surface

Climate

DataSet

(SURF_CLI_CHN_MUL_DAY_V3.0)

http://www.escience.gov.cn/metdata/page/index.html. In China Met. Data Service. 27. NBS Agriculture Statistical Yearbook of Guangdong.; National Bureau of Statistics of the PRC: China Statistics Press, 1999-2012. 28. WRD Bulletin of Guangdong Water Resources Water Resources Department of Guangdong province: 1980-2012. 29. CAS, Characteristics of Soil Horizon A http://www.soil.csdb.cn/. In China Soil Scientific Database. 30. DLR The Second Survey of National Land Use 2009 http://www.gdstats.gov.cn/tjzl/tjgb/201403/t20140324_140367.html; Department of Land and Resources of Guangdong province. 31. MOA, Yields of Crops, Vegetables and Fruits in Guangdong Province http://www.zzys.moa.gov.cn/. In Ministry of Agriculture of PRC. 32. NBS China Statistical Yearbook. ; National Bureau of Statistics of the PRC.

In China Statistics Press:

1996-2013. 33. MEP Exposure Factors Handbook of Chinese Population (Adults); Ministry of Environmental Protection of the PRC. In China Environment Press: 2013. 34. USEPA Risk assessment guidance for superfund: Volume iii: Part A, process for conducting probabilistic risk assessment; Office of Emergency and Remedial Response, U.S. Environmental Protection Agency: Washington, D.C., 2001. 35. Huang, M.; Wang, W.; Leung, H.; Chan, C.; Liu, W. K.; Wong, M. H.; Cheung, K. C., Mercury levels in road dust and household TSP/PM2.5 related to concentrations in hair in Guangzhou, China. Ecotoxicology and Environmental Safety 2012, 81, 27-35. 36. Xu, L.; Chen, J.; Yang, L.; Yin, L.; Yu, J.; Qiu, T.; Hong, Y., Characteristics of total and methyl mercury in wet deposition in a coastal city, Xiamen, China: Concentrations, fluxes and influencing factors on Hg distribution in precipitation. Atmospheric Environment 2014, 99, 10-16. 37. Guo, Y.; Feng, X.; Li, Z.; He, T.; Yan, H.; Meng, B.; Zhang, J.; Qiu, G., Distribution and wet deposition fluxes of total and methyl mercury in Wujiang River Basin, Guizhou, China. Atmospheric Environment 2008, 42, (30), 7096-7103. 25

ACS Paragon Plus Environment

Environmental Science & Technology

566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609

38. Feng, X.; Sommar, J.; Lindqvist, O.; Hong, Y., Occurrence, Emissions and Deposition of Mercury during Coal Combustion in the Province Guizhou, China. Water, Air, & Soil Pollution 2002, 139, (1-4), 311-324. 39. Zhang, X.; Siddiqi, Z.; Song, X.; Mandiwana, K. L.; Yousaf, M.; Lu, J., Atmospheric dry and wet deposition of mercury in Toronto. Atmospheric Environment 2012, 50, 60-65. 40. Sakata, M.; Marumoto, K., Wet and dry deposition fluxes of mercury in Japan. Atmospheric Environment 2005, 39, (17), 3139-3146. 41. Fang, G. C.; Yang, I. L.; Liu, C. K., Estimation of Atmospheric Particulates and Dry Deposition Particulate-bound Mercury Hg(p) in Sha-Lu, Taiwan. Aerosol Air Qual. Res. 2010, 10, (5), 403-413. 42. Fang, F.; Wang, Q.; Li, J., Atmospheric particulate mercury concentration and its dry deposition flux in Changchun City, China. Science of The Total Environment 2001, 281, (1–3), 229-236. 43. Wang, Z.; Zhang, X.; Chen, Z.; Zhang, Y., Mercury concentrations in size-fractionated airborne particles at urban and suburban sites in Beijing, China. Atmospheric Environment 2006, 40, (12), 2194-2201. 44. Fang, F.; Wang, Q.; Li, J., Urban environmental mercury in Changchun, a metropolitan city in Northeastern China: source, cycle, and fate. Science of The Total Environment 2004, 330, 159. 45. Zhu, J. S.; Wang, T.; Talbot, R. W.; Mao, H.; Yang, X. Q.; Fu, C.; Sun, J.; Zhuang, B.; Li, S.; Han, Y. S., Characteristics of atmospheric mercury deposition and size-fractionated particulate mercury in urban Nanjing, China. Atmospheric Chemistry and Physics 2014, 14, (5), 2233-2244. 46. Yang, H.; Berry, A.; Rose, N. L.; Berg, T., Decline in atmospheric mercury deposition in London. Journal of Environmental Monitoring 2009, 11, (8), 1518-1522. 47. Fu, X. W.; Zhang, H.; Yu, B.; Wang, X.; Lin, C. J.; Feng, X. B., Observations of atmospheric mercury in China: a critical review. Atmospheric Chemistry and Physics 2015, 15, (16), 9455-9476. 48. Gustin, M. S.; Amos, H.; Huang, J.; Miller, M. B.; Heidecorn, K., Measuring and modeling mercury in the atmosphere: a critical review. Atmospheric Chemistry and Physics 2015, 15, (10), 5697-5713. 49. Huang, J.; Choi, H.; Landis, M. S.; Holsen, T. M., An application of passive samplers to understand atmospheric mercury concentration and dry deposition spatial distributions. Journal of Environmental Monitoring 2012, 14, (11), 2976-2982. 50. Zhang, L.; Wright, L. P.; Blanchard, P., A review of current knowledge concerning dry deposition of atmospheric mercury. Atmospheric Environment 2009, 43, (37), 5853-5864. 51. Risch, M.; Dewild, J. F.; Krabbenhoft, D. P.; Kolka, R. K.; Zhang, L., Litterfall mercury dry deposition in the eastern USA. Environmental Pollution 2012, 161, 284-290. 52. Zhou, J.; Feng, X.; Liu, H.; Zhang, H.; Fu, X.; Bao, Z.; Wang, X.; Zhang, Y., Examination of total mercury inputs by precipitation and litterfall in a remote upland forest of Southwestern China. Atmospheric Environment 2013, 81, 364-372. 53. Wetherbee, G. A.; Gay, D. A.; Brunette, R. C.; Sweet, C. W., Estimated variability of National Atmospheric Deposition Program/Mercury Deposition Network measurements using collocated samplers. Environmental Monitoring and Assessment 2007, 131, 49-69. 54. MEP Environmental quality evaluation standards for farmland of edible agriculture products (HJ/T332-2006); Ministry of Environmental Protection of the PRC. In China Envionmental Science Press: 2006. 55. MEP Environmental quality evaluation standards for farmland of greenhouse vegetables production (HJ/T333-2006); Ministry of Environmental Protection of the PRC. In China Environmental Science Press: 2006. 56. MEP Chinese element background value in soil; In China Environmental Science Press: 1990. 57. NHFPC National food safety standard maximum levels of pollutants in foods in China (GB2762-2012); National health and family planning commission of the PRC.

In China Standards Press: 2012.

58. Chang, C. Y.; Yu, H. Y.; Chen, J. J.; Li, F. B.; Zhang, H. H.; Liu, C. P., Accumulation of heavy metals in leaf 26

ACS Paragon Plus Environment

Page 26 of 31

Page 27 of 31

610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653

Environmental Science & Technology

vegetables from agricultural soils and associated potential health risks in the Pearl River Delta, South China. Environmental Monitoring and Assessment 2013, 186, (3), 1547. 59. Cheng, Z.; Liang, P.; Shao, D.; Wu, S.; Nie, X.; Chen, K.; Li, K.; Wong, M., Mercury Biomagnification in the Aquaculture Pond Ecosystem in the Pearl River Delta. Archives of Environmental Contamination and Toxicology 2011, 61, (3), 491-499. 60. Wei, Z.; Shichang, K.; Xinbin, F.; Qianggong, Z.; Chaoliu, L. I., Mercury speciation and spatial distribution in surface waters of the Yarlung Zangbo River, Tibet. Chinese Science Bulletin 2010, 55, (24), 2697-2703. 61. Feng, X., Shi, J., Jiang, G. , Mercury pollution in China—an overview. In

Dynamics of Mercury Pollution on

Regional and Global Scales. Springer: U.S., 2005. 62. Zhang, H.; Feng, X.; Larssen, T.; Qiu, G.; Vogt, R. D., In Inland China, Rice, Rather than Fish, Is the Major Pathway for Methylmercury Exposure. Environmental Health Perspectives 2010, 118, (9), 1183. 63. USEPA Integrated Risk Information System — Methylmercury (MeHg) (CASRN22967-92-6); National Center for Environmental Assessment, U.S. Environment Protection Agency: 2015. 64. USEPA Integrated Risk Information System — Mercuric chloride (HgCl2); CASRN 7487-94-7; National Center for Environmental Assessment, U.S. Environmental Protection Agency: 2015. 65. Shao, D.; Liang, P.; Kang, Y.; Wang, H.; Cheng, Z.; Wu, S.; Shi, J.; Lo, S. C. L.; Wang, W.; Wong, M. H., Mercury species of sediment and fish in freshwater fish ponds around the Pearl River Delta, PR China: Human health risk assessment. Chemosphere 2011, 83, (4), 443-448. 66. Asselt, M. B. A. V.; Rotmans, J., Uncertainty in Integrated Assessment Modelling. Climatic Change 2002, 54, (1-2), 75-105. 67. Walker, W. E.; Harremoës, P.; Rotmans, J.; Sluijs, J. P. v. d.; Asselt, M. B. A. v.; Janssen, P.; Krauss, M. P. K. v., Defining Uncertainty: A Conceptual Basis for Uncertainty Management in Model-Based Decision Support. Integrated Assessment 2003, volume 4, (1), 5-17. 68. Kumar, V.; Mari, M.; Schuhmacher, M.; Domingo, J. L., Partitioning total variance in risk assessment: Application to a municipal solid waste incinerator. Environmental Modelling & Software 2009, 24, (2), 247-261. 69. NTU Compilation of Exposure Factors; Colleague of Public Health, National Taiwan University: 2008. 70. USEPA, Exposure Factors Handbook. Office of Reeach and Development. National Center for Environmental Assessment. U.S. Environmental Protection Agency. Washingtong, DC 20460. 1997. 71. USEPA Exposure Factors Handbook: 2011 Eddition; National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency: Washington, D.C., 2011. 72. Amos, H. M.; Jacob, D. J.; Streets, D. G.; Sunderland, E. M., Legacy impacts of all-time anthropogenic emissions on the global mercury cycle. Global Biogeochemical Cycles 2013, 27, (2), 410-421. 73. Chen, L.; Frauenfeld, O., Impacts of urbanization on future climate in China. Clim Dyn 2015, 1-13. 74. Wang, X.; Liao, J.; Zhang, J.; Shen, C.; Chen, W.; Xia, B.; Wang, T., A Numeric Study of Regional Climate Change Induced by Urban Expansion in the Pearl River Delta, China. Journal of Applied Meteorology & Climatology 2014, 53, (2), 346-362. 75. Chang, M.; Fan, S.; Fan, Q.; Chen, W.; Zhang, Y.; Wang, Y.; Wang, X., Impact of refined land surface properties on the simulation of a heavy convective rainfall process in the Pearl River Delta region, China. Asia-Pacific J Atmos Sci 2014, 50, (1), 645-655. 76. Schets, F. M.; Schijven, J. F.; de Roda Husman, A. M., Exposure assessment for swimmers in bathing waters and swimming pools. Water research 2011, 45, (7), 2392-2400. 77. EA Soil Guideline Values for mercury in soil; Environment Agency United Kingdom, 2009.

78. USEPA SCL Table http://www.epa.gov/risk/regional-screening-table; U.S. Environmental Protection Agency: 2015. 27

ACS Paragon Plus Environment

Environmental Science & Technology

Figure 1. Distribution (10000 trials, 5-95%, Line: Lognormal fit, column: forecast values of the TDI of Hg by adults (left panel) and children (right panel) in the 10-year projections.

28

ACS Paragon Plus Environment

Page 28 of 31

Page 29 of 31

Environmental Science & Technology

Figure 2. Contribution (%) of each type of intake to the variance of the (1) TDI by adults and children (0-12 year) (the upper two rows of charts) and (2) DDI by two different age groups of children (the bottom two rows of charts) in the 10-year projections (A: in “without soil background” scenario, B: in “with soil background” scenario)

29

ACS Paragon Plus Environment

Environmental Science & Technology

Figure 3. Probabilities of health risks (HQs>1) caused by Hg2+ and MeHg respectively.

30

ACS Paragon Plus Environment

Page 30 of 31

Page 31 of 31

Environmental Science & Technology

TOC/Abstract Graphic

31

ACS Paragon Plus Environment