Increases of Total Mercury and Methylmercury Releases from

Subscriber access provided by University of Florida | Smathers Libraries

Article

Increases of Total Mercury and Methylmercury Releases from Municipal Sewage into Environment in China and Implications Maodian Liu, Peng Du, Chenghao Yu, Yipeng He, Haoran Zhang, Xuejun Sun, Huiming Lin, Yao Luo, Han Xie, Junming Guo, Yindong Tong, Qianggong ZHANG, Long Chen, Wei Zhang, Xiqing Li, and Xuejun Wang Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.7b05217 • Publication Date (Web): 07 Dec 2017 Downloaded from http://pubs.acs.org on December 7, 2017

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 36

Environmental Science & Technology

1 2

Increases of Total Mercury and Methylmercury Releases from Municipal Sewage into Environment in China and Implications

3 4 5

⊥ Maodian Liu†‡, Peng Du†, Chenghao Yu†, Yipeng He†‡, Haoran Zhang†, Xuejun Sun§ , Huiming Lin†, Yao Luo†, Han Xie†, Junming Guoǁ, Yindong Tong#, Qianggong Zhang§∇, Long Chen○◆, Wei Zhang¶, Xiqing Li†, Xuejun Wang†*

6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

†Ministry of Education Laboratory of Earth Surface Process, College of Urban and Environmental Science, Peking University, Beijing 100871, China ‡Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Rd., Groton, CT 06340, USA §Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China ⊥Graduate University of the Chinese Academy of Sciences, Beijing 100049, China ǁState Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China #School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China ∇Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China ○Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai 200241, China ◆School of Geographic Sciences, East China Normal University, Shanghai 200241, China ¶School of Environment and Natural Resources, Renmin University of China, Beijing 100872, China

27

Corresponding authors:

28 29 30

Xuejun Wang. Ministry of Education Laboratory of Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China. Tel: +86-10-62759190. E-mail: [email protected]

31

Word count for text: 4,995

32

Word count for 6 figures: 6 × 300 = 1,800

33

Total word count: 6,795

ACS Paragon Plus Environment


34

ABSTRACT: As a globally transported pollutant, mercury (Hg) released from human

35

activity and methylmercury (MeHg) in the food web are global concerns due to their

36

increasing presence in the environment. In this study, we found that Hg released from

37

municipal sewage into the environment in China is a substantial anthropogenic source

38

based on mass sampling throughout China. In total, 160 Mg (140-190 Mg, from the

39

20th percentile to the 80th percentile) of Hg (THg) and 280 kg (240-330 kg) of MeHg

40

were released from municipal sewage in China in 2015. The quantities of released

41

THg and MeHg were the most concentrated in the coastal regions, especially in the

42

East, North and South China regions. However, the per capita release of THg and

43

MeHg was the highest in the Tibetan region, which is recognized as the cleanest

44

region in China. THg released into aquatic environments was mitigated from 2001 to

45

2015 in China, but the amounts released into other sinks increased. This study

46

provides the first picture of the release of Hg from municipal sewage into various

47

sinks in China, and policy makers should pay more attention to the diversity and

48

complexity of the sources and transport of Hg, which can lead to Hg accumulation in

49

the food web and can threaten human health.


Page 2 of 36

Page 3 of 36


50

INTRODUCTION

51

Mercury (Hg) can cycle through the atmosphere, hydrosphere and pedosphere;

52

bio-magnify in the food web; and threaten the health of wildlife and humans.1-3 Hg is

53

a naturally occurring element, but human activities have altered the global

54

biogeochemical cycle of Hg.4-6 Quantification of the total Hg (THg) amount released

55

into the atmosphere, hydrosphere and pedosphere on a global scale has been

56

performed.7-11 Substantial amounts of anthropogenic THg have been emitted into the

57

atmosphere from China in recent years.12-14 In total, 530 Mg of anthropogenic THg

58

was emitted into the atmosphere by China in 2014,14 and the global THg emissions

59

ranged from 2,000 to 2,300 Mg in 2010.9, 15 The release of anthropogenic Hg into

60

aquatic environments is also critical since this can directly influence the Hg levels in

61

fish and other biota.16-18 The intake of fish contaminated with Hg, primarily as

62

methylmercury (MeHg), has already resulted in severe impacts on humans over the

63

past century, such as the emergence of Minamata Disease in Japan.19 In total, 100 Mg

64

of anthropogenic THg was directly released into aquatic environments in China in

65

2012,20 and the annual global THg release in recent years was 1,100 Mg.5 Compared

66

with the release of THg into the atmosphere and aquatic environments, the

67

quantification of THg released into land is insufficient. Hui et al. indicated that 650

68

Mg of anthropogenic THg was released into the land in China in 2010,10 but the study

69

lacked details regarding Hg sinks. In China, an abundance of municipal solid waste

70

has been applied to croplands and should not be ignored.21 The direct emission of

71

THg in China has continuously increased,14 but the amount of THg released into



72

aquatic environments in China has decreased since 2001.20 The trend in the amount of

73

THg released into land is still unclear in China and should be studied since the release

74

of anthropogenic Hg into land may cause an increase in Hg levels in rice, which can

75

result in higher levels of Hg exposure in humans.22, 23

76

Previous studies have focused on the release of some pollutants associated with

77

municipal sewage in China, such as photoinitiators,24 chlorinated paraffins and

78

polycyclic aromatic hydrocarbons.25,

79

focused mainly on primary industries, such as coal-fired power plants,27 nonferrous

80

metal smelting, polyvinyl chloride production and other intentional uses.28-30 In a

81

previous paper, we indicated that the release of THg from municipal sewage may be a

82

primary source for the direct release of anthropogenic THg into aquatic environments,

83

but the data associated with municipal sewage are insufficient.20 THg releases into the

84

atmosphere and land from municipal sewage treatment plants (MSTPs) in China are

85

still unclear. In total, 30 Tg of sewage sludge was produced from MSTPs in China in

86

2015, which is a large increase from the 11 Tg released in 2005.31 In 2015, 20% of the

87

sewage sludge produced from MSTPs was applied to croplands31, thereby having the

88

potential to increase the exposure of the Chinese population to Hg through rice and

89

livestock (e.g., poultry) intake.32, 33 Few studies have focused on the release of MeHg

90

from anthropogenic sources at the national level in China. Previous studies have

91

indicated that municipal sewage discharge can significantly influence the pollution

92

level and the health of fish.34, 35 The MeHg released from municipal sewage and other

93

anthropogenic sources should not be ignored.

26

For Hg, previous studies in China have


Page 4 of 36

Page 5 of 36


94

In this study, we aim to quantify the release of THg and MeHg from municipal

95

sewage into aquatic environments (i.e., rivers, lakes and sea-adjacent waters) in China

96

based on measurements of municipal sewage samples (including untreated and treated

97

sewage). We also provide a comprehensive understanding of the release of THg from

98

municipal sewage into other various sinks (i.e., aquatic environments, landfills,

99

croplands, urban areas, natural land and the atmosphere) in China from 2001 to 2015

100

based on material flow analysis. This study is motivated by our recognition of the

101

potential role of Hg released from municipal sewage into the environment, and it is

102

intended to support policy making in China and the implementation of the Minamata

103

Convention.

104

MATERIALS AND METHODS

105

Sample Collection. Samples were collected from 62 MSTPs in 24 provinces and

106

municipalities from July 2014 to Aug 2016 following a technique used in previous

107

studies.24, 36 Sample sites were selected based on the population distribution in China

108

(“Hu Huanyong Line”, Figure 1) and were concentrated in the eastern regions of

109

China,20, 37 in particular, the North, East and South China regions, which are the three

110

most developed regions with the largest population densities in China. In each of

111

these regions, five or more MSTPs were selected for municipal sewage sample

112

collection. Detailed information on the MSTPs is provided in Table S1, Supporting

113

Information. In total, the cities where these sample sites were located have a

114

combined population of 260 million people (40% of the total urban population of



115

China) in 2010 (Figure 1).

116

All MSTPs were sampled for two days, i.e., one weekend day and one week day,36

117

for THg and MeHg analyses. Influent sewage (untreated sewage) and effluent sewage

118

(treated sewage) were collected as 24 h composite samples by autosamplers, FC-9624

119

(GRASP Science & Technology, China), ISCO 3000, 3700, 4700 (Teledyne

120

Technologies, USA), and GD-24A (Jinpeng Huanyi Technology, China), based on a

121

previous study.36 We programed the autosamplers to sample 100 mL of the sewage

122

each hour using acid-cleaned Teflon tubing. The samples were collected in

123

acid-cleaned glass or polycarbonate bottles.38,

124

avoided during sampling.36 Following the collection, the samples were preserved by

125

adding 4 ml/L of pre-tested 11.6 M trace metal-grade HCl and stored under cool and

126

dark conditions following U.S. EPA methods 1631E and 1630, and they were then

127

express-delivered to labs as soon as possible (within 24 h).24, 39 Samples from each

128

site were filtered through 0.45-µm pore size cellulose nitrate membranes (Whatman,

129

product code 10401170) to analyze the particulate THg and MeHg and were preserved

130

by freezing.38, 39

39

Heavy precipitation days were

131

Analytical Methodology. Sewage samples were taken in triplicate and analyzed for

132

THg and MeHg following U.S. EPA methods 1631E and 1630. Briefly, for dissolved

133

THg, all the samples were oxidized to Hg(II) with BrCl; the free halogens were

134

destroyed by NH2OH·HCl, and Hg(II) was converted to Hg(0) using SnCl2. The

135

samples were analyzed by cold vapor atomic fluorescence spectrometry (CVAFS,


Page 6 of 36

Page 7 of 36


136

Tekran model 2600). Analysis of dissolved THg was completed at the Institute of

137

Tibetan Plateau Research of the Chinese Academy of Sciences. For dissolved MeHg,

138

the samples were placed in fluoropolymer distillation vessels and distilled into

139

receiving vessels at 125 °C under a N2 flow. After the distillation, the samples were

140

adjusted to pH 4.9 with an acetate buffer and ethylated by the addition of sodium

141

tetraethyl borate (NaBEt4). The samples were analyzed by cold vapor atomic

142

fluorescence spectrometry (GC-AFS, Tekran model 2700) at Peking University.

143

For particulate THg, filters containing particles from filtering 50 to 500 mL of

144

municipal sewage were analyzed by a DMA-80 (U.S. EPA method 7473) at Peking

145

University based on a previous study.40 For particulate MeHg, filters containing the

146

particles were digested with 4.57 M of trace metal-grade HNO3 in a water bath (60 °C)

147

for 12 h, neutralized with KOH, buffered with acetate, and ethylated with NaBEt4

148

based on previous studies.39, 40 The particulate MeHg samples were analyzed by cold

149

vapor atomic fluorescence spectrometry (GC-AFS, Tekran model 2700). We analyzed

150

the dissolved THg and dissolved MeHg of each sample in triplicate and the particulate

151

THg and particulate MeHg of each sample in duplicate. The detection limits for the

152

dissolved THg, particulate THg, and both the dissolved and particulate MeHg

153

analyses were 0.1 ng/L, 0.1 ng/g and 0.01 ng/L, respectively, which were calculated

154

based on the average concentrations of the method blanks plus triple the standard

155

deviation of the blanks. The individual internal standard spike recoveries for the

156

dissolved THg, particulate THg, dissolved MeHg and particulate MeHg analyses were

157

94 ± 5%, 97 ± 3%, 83 ± 9% and 87 ± 9%, respectively. All the concentration data



158

Page 8 of 36

were adjusted using the individual internal standard spike recoveries.38

159

We divided mainland China into 8 regions (Figure S1, Supporting Information). In

160

some provinces, municipal sewage samples were unavailable, and we used the

161

concentration data from other provinces in the same region to estimate the data in

162

these provinces based on a population-weighted method.41,

163

effluent sewage samples were unavailable (Table S1, Supporting Information);

164

therefore, we modeled the samples based on a fitting model for the Hg concentration

165

data of the influent and effluent sewage of the other MSTPs. The fitting error of each

166

model was considered in the uncertainty analysis. Statistical analysis was conducted

167

using R version 3.3.2 (R Foundation for Statistical Computing, Vienna, Austria).

168

Significant levels were determined to be at the P < 0.05 level.

42

For some MSTPs,

169

Hg Released from Municipal Sewage. We applied a model that was developed in

170

a previous study to estimate the primary release of anthropogenic aquatic Hg to model

171

the release of THg and MeHg from municipal sewage in China.20 Parameterization of

172

the model was accomplished using Monte Carlo simulations.20 The concentrations of

173

THg

174

(Kolmogorov-Smirnov test, P > 0.05). In the model, aquatic Hg released from

175

different anthropogenic sources was divided into two groups.20 The first group was

176

based on measured Hg concentration data, and the second group was based on a

177

method developed by AMAP/UNEP.43 In this study, we used the first group to

178

estimate the probabilistic distribution of the release of THg and MeHg from municipal

and

MeHg

in

this

study

followed


log-normal

distributions

Page 9 of 36


179

sewage, as given below:20

= , × × 1

180

where is the probabilistic distribution of the flux of THg (i=1) (Mg/yr) or

181

MeHg (i=2) (kg/yr) released from municipal sewage for all of China, , is the

182

probabilistic distribution of the concentration of THg or MeHg (ng/L) in the untreated

183

sewage of province j, is the total annual volume (104 m3/yr) of municipal sewage

184

produced from province j (Figure S2, Supporting Information), and is the unit

185

conversion factor for THg (10-8) or MeHg (10-5). Data for the municipal sewage

186

discharge in each province were collected from the China Environmental Statistical

187

Yearbook (Figure S2, Supporting Information).44

188

Material Flow Analysis. As an effective tool to provide a system-oriented view of

189

the interlinked processes and to support policy decisions,45, 46 material flow analysis

190

was applied to provide a better understanding of THg and MeHg transport in the

191

sewage-environment systems in this study. Parameterization of the analysis model

192

was accomplished using Monte Carlo simulations. The concentrations of THg and

193

MeHg in this study follow log-normal distributions. Similar to Allesch and Brunner’s

194

study,45 we began the Hg material flow with a municipal sewage input into the system,

195

continued with the treatment and transport (i.e., MSPT, sewage sludge and

196

incineration), and ended with the release into various sinks (i.e., aquatic environments,

197

land and atmosphere). The method was established based on the mass balance



198

principle to ensure that the amount in the sources was equal to the amount in the sinks,

199

and the temporary storages changes and the mass balance is provided below:45

= , × , × + , × , × 2

#

= !"# × $# 3 #

)

!"# × $# = &'() × $) 4

200

where is the probabilistic distribution of source l of THg (Mg/yr) or

201

MeHg (kg/yr) released from municipal sewage in province j. We divided the source

202

into two groups (g). One is the release of THg or MeHg associated with untreated

203

sewage, and the other one is associated with treated sewage based on a previous

204

study.20 , and , are the probabilistic distributions of the THg or MeHg

205

concentrations (ng/L) in untreated sewage and treated sewage from province j,

206

respectively; , and , are the annual volumes (104m3/yr) of the untreated

207

sewage and treated sewage in province j, respectively (Figure S3, Supporting

208

Information); !"# is the probabilistic distribution of the temporary

209

storage, n (i.e., MSTP, sewage sludge and incineration), of THg (Mg/yr) or MeHg

210

(kg/yr) in province j; &'() is the probabilistic distribution of sink m (i.e.,

211

rivers, lakes, oceans, landfills, croplands, natural lands, atmosphere and urban areas)

212

for THg (Mg/yr) or MeHg (kg/yr) in province j; and P is the percentage of sewage or

213

sewage sludge transported from the last tier into the source or temporary storage (%).


Page 10 of 36

Page 11 of 36


214

The material flow analysis was run from 2001 to 2015 in this study. In the

215

sewage-environment system, the THg and MeHg concentrations transported into

216

different temporary storage locations or sinks were estimated based on the transport

217

process and the sewage or sewage sludge sinks in different provinces (Figure S2,

218

Supporting Information). Municipal sewage originates from urban areas, but urban

219

areas can also serve as sinks and accept flows, such as reused treated sewage (e.g.,

220

reuse in industry, municipal services and landscape water) and sewage sludge (e.g.,

221

building material). The MeHg flows ended being transported into sewage sludge in

222

the MSTP since the mechanisms of Hg methylation and MeHg demethylation in

223

sewage sludge are unclear. THg emissions from sewage sludge (after being released

224

into land) were considered legacy sources for the atmosphere. The annual emission

225

rates of THg from landfills and from the irregular dumping of sewage were referenced

226

from a previous study,47 ranging from 3.0×10-6 to 9.0×10-6 and 1.0×10-3 to 2.0×10-3 g

227

per ton of annual mass of disposed wastes, respectively. The mean values (6.0×10-6

228

and 1.5×10-3) were estimated based on the ranges,11 and we reran them using the

229

Monte Carlo method to get the median values and P20-80 confidence intervals. The

230

THg emission rate from sewage sludge after its application to croplands was assumed

231

to be the same as that for the emission from landfills due to the lack of data. The

232

percentage of THg emissions from the incineration of sewage sludge was set at 48%

233

(29%-75%, P20-80 confidence interval) based on previous studies.48-52 The large

234

uncertainty in this section is due to unknown pollution emissions from the

235

incineration of sewage sludge in China.48-52 We used the median value to avoid



236

overestimating this portion and considered the range in the uncertainty analysis based

237

on the Monte Carlo simulation.20 Most THg in influent sewage can transfer into the

238

sewage sludge in the treatment process48, 49 based on the mass balance principle. We

239

modeled the median THg concentrations in the sewage sludge for the MSPTs in each

240

province and compared them with published measurement data to ensure that the

241

material flow analysis was reasonable. The modeling process is provided below:

+, =

, × , × − , × , × 5 -

242

where +, is the probabilistic distribution of the THg concentration (µg/g) in

243

sewage sludge in province j, and - is the annual mass of sewage sludge (104 Mg/yr)

244

yielded by province j.

245

Uncertainty Analysis. A Monte Carlo simulation (10,000 runs) was applied to

246

analyze the robustness of the inventories and material flow analyses of THg and

247

MeHg.20, 53 The concentrations of THg and MeHg in this study followed log-normal

248

distributions. The municipal sewage discharge data and other activity levels (such as

249

sewage sludge production data) were all obtained from official statistics.31 A uniform

250

distribution with a fixed coefficient of deviation (5%) was assumed for the official

251

statistical data based on previous studies.20, 42 The median values and the P20-80

252

confidence intervals of the statistical distributions were modeled to quantify the THg

253

and MeHg fluxes and to characterize the uncertainty.20, 53

254

RESULTS AND DISCUSSION


Page 12 of 36

Page 13 of 36


255

THg and MeHg Released from Municipal Sewage. The average THg

256

concentration

in

untreated

sewage

in

257

(population-weighted average ± standard deviation) in recent years, and this is nearly

258

one thousand times higher than THg concentrations in general freshwater systems in

259

China.54-56 The highest THg concentration in untreated sewage was found in Tibet

260

(15,000 ± 4,400 ng/L), followed by the Heilongjiang province (8,900 ± 4,000 ng/L)

261

and Beijing city (5,700 ± 3,000 ng/L) (Figure 2). The highest THg concentration in

262

untreated sewage in Tibet might be explained by traditional Tibetan medicines,

263

cinnabar or gold amalgam (please see details below). The THg concentrations in most

264

provinces in China were typically higher than those in other countries (such as Brazil,

265

Canada and the U.S., ranging from 61 to 310 ng/L),49, 57-59 but they were similar to

266

previous measurement results in China (ranging from 260 to 14,000 ng/L, Figure 2,

267

Table S2, Supporting Information).60,

268

municipal sewage in China are complicated. In addition to household contributions,

269

the THg in municipal sewage partly originates from industrial wastewater and

270

road-deposited sediment input associated with rainfall.31,

271

concentration in treated sewage in China was 160 ± 130 ng/L. Approximately 95% of

272

the THg in the influent sewage transferred into the sewage sludge.

61

China

was

3,400

±

2,600

ng/L

This is because the sources of THg in

62

The average THg

273

For MeHg, the average concentration in untreated sewage in China was 6.5 ± 5.5

274

ng/L, which is tens of times higher than MeHg concentrations in general freshwater

275

systems in China.54-56 The highest MeHg concentration in untreated sewage was also

276

found in Tibet (17 ± 1.8 ng/L), followed by the Sichuan province (14 ± 13 ng/L) and



277

Shanghai city (13 ± 8.1 ng/L) (Figure 2). The MeHg concentrations in the untreated

278

sewage were similar to data from other countries and previous studies in China (Table

279

S2, Supporting Information).49, 57-61 The average concentration in treated sewage in

280

China was 1.0 ± 0.82 ng/L. Approximately 85% of the MeHg in influent sewage was

281

removed by MSTPs in China.

282

In total, 160 Mg (140-190 Mg of the P20-80 confidence interval, Figure S4,

283

Supporting Information) and 280 kg (240-330 kg) of THg and MeHg, respectively,

284

were released from municipal sewage in 2015. As an important anthropogenic source

285

that has previously been ignored,10,

286

constituted 12% of the total anthropogenic THg released (including direct and

287

secondary anthropogenic releases) in China.10 There is no total anthropogenic release

288

data for MeHg. The substantial contribution of THg in municipal sewage in China is a

289

result of the following: 1) a large amount of municipal sewage was generated in

290

recent years due to the rapid increase in the urban population and improvement in

291

living standards,63 and 2) high THg levels were found in untreated sewage, as

292

mentioned above (Figure 2).

13

THg released from municipal sewage

293

We constructed high-resolution inventories of THg and MeHg released from

294

municipal sewage in China in 2015 based on the fitting models (Figure 3). The results

295

show that the release of THg and MeHg was concentrated in the eastern regions of

296

China, especially in the coastal regions. The Beijing-Tianjin-Hebei (North China),

297

Yangtze River delta (East China), Pearl River delta (South China) and Sichuan


Page 14 of 36

Page 15 of 36


298

province regions were among the top contributors to the THg and MeHg

299

concentrations in municipal sewage (Figure 3a and b) due to their high population

300

densities. This is similar to previous studies, which indicated that other anthropogenic

301

emissions, such as black carbon,42 phosphorus and antibiotics, are also high in these

302

regions.37, 64 The proportion of the MeHg to the THg released in the coastal regions

303

(0.35%) was significantly higher than that in the inland regions (0.22%) (P < 0.05),

304

which was partly due to the high rates of fish consumption in the coastal regions,

305

especially in North (such as Beijing) and East China (such as Shanghai).63 The

306

amount of THg released from municipal sewage was also high in Northeast China, but

307

the amount of MeHg released was not. In the western regions of China, high release

308

intensities of THg and MeHg were found in major urban areas such as Lanzhou in

309

Gansu province.

310

However, Tibet had the highest per capita release of THg and MeHg in 2015,

311

followed by Shanghai and Beijing (Figure 3c and d). In Tibet, households may be the

312

major contributors to the release of THg and MeHg from municipal sewage due to the

313

lack of industry and business activities in this area. One explanation could be the

314

intake of traditional Tibetan medicines by Tibetan inhabitants. Traditional Tibetan

315

medicines, i.e., medicine commonly used by Tibetans, contain abundant quantities of

316

inorganic Hg because pharmacists have intentionally added heavy metals, including

317

Hg, into medicine as therapeutic ingredients for more than 1,000 years in the Tibetan

318

region.65 A previous study found that the THg concentrations in medicines ranged

319

from 0.37 to 15 mg/g,65 which are ten thousand times higher than the THg



320

concentrations in fish. A previous study indicated that most of the inorganic Hg in the

321

medicines does not accumulate in the human body.65 Therefore, the excretion of

322

inorganic Hg from the human body may result in high levels of inorganic Hg in

323

municipal sewage in Tibetan urban areas.65, 66 In addition, cinnabar, which is used for

324

their cloths and tapestry, and gold amalgam, which is used for their religious items,

325

might also contribute to the high THg concentration in Tibetan municipal sewage. In

326

total, 3.5 Mg of THg was released from municipal sewage in the urban areas in the

327

Tibetan region. The measurement of MeHg levels in traditional Tibetan medicine is

328

still lacking. Fish consumption is low in the Tibetan region (approximately 10-fold

329

lower than the average consumption in China).63 The highest per capita release of

330

MeHg in the Tibetan region may be mainly attributed to medicine usage. Further

331

studies on the MeHg levels in traditional Tibetan medicines should be carried out.

332

THg and MeHg Material Flows from Municipal Sewage to Sinks. We

333

determined that both the THg and MeHg released from municipal sewage rapidly

334

increased from 2001 to 2015 (Figure 5b and c), which corresponded to an increase in

335

the Chinese population during this period.63 The results of the material flow analysis

336

indicate that 23 (14% of the THg released from municipal sewage), 120 (77%) and 15

337

Mg (9.4%) of THg from municipal sewage was released into aquatic environments,

338

land and the atmosphere, respectively, in 2015 in China (Figure 5a). This is different

339

from the amounts of other major pollutants, such as nonferrous smelting and

340

polyvinyl chloride production, in China, in which the atmosphere is their primary sink

341

(more than 50% of the total release).28, 29 East China was the primary contributor to


Page 16 of 36

Page 17 of 36


342

the total THg released from the municipal sewage during this period, followed by

343

Northeast China (Figure 6a). For MeHg, 63 kg was directly released into aquatic

344

environments in China in 2015. The proportion of MeHg released to land is unclear.

345

High-resolution inventories of the THg and MeHg released into aquatic environments

346

and THg released into the land and atmosphere from municipal sewage in 2015 are

347

provided in Figure S5 to S8, respectively (Supporting Information).

348

A previous study divided the sinks for anthropogenic THg into aquatic

349

environments, land and the atmosphere in China.10 In this study, we determined that

350

the role of land as a sink for THg and possibly for MeHg is more complicated. As a

351

sink, land contains various sub-sinks, e.g., natural lands, landfills, croplands and

352

urban areas (Figure 5). Some part of the THg generated from the incineration of

353

sewage sludge will become ash and will be released into the land.31 Landfills received

354

64% of the total THg release into land in 2015. Croplands received 21% of the total

355

THg release into land in 2015, which can be absorbed by crops such as rice and can

356

directly threaten local human health.23 Previous studies also indicated that the use of

357

sewage sludge as an agricultural fertilizer can spread large amounts of THg into

358

cropland.5 A portion of the THg associated with sewage sludge was irregularly

359

dumped into natural land, but this amount was less substantial (0.67% in 2015). The

360

THg stored in landfills and building materials may be released into the environment in

361

the future.

362

In total, 15 Mg of THg was emitted from the lifecycle of municipal sewage into the



363

atmosphere in China in 2015. The THg in landfills and croplands is a legacy source

364

for the atmosphere, but it is less significant (< 0.10 Mg in 2015). However, the THg

365

emission from the incineration of sewage sludge showed the highest contribution to

366

the total THg emission associated with municipal sewage. Zhang et al. indicated that

367

12 Mg of THg was emitted from municipal solid waste incineration (including sewage

368

sludge and other municipal solid waste) in 2010,67 and Tian et al. estimated 37 Mg in

369

2010.68 The disparity between the different studies can be attributed to the selection of

370

different emission factors and methods used for estimations.67 In this study, we

371

estimated THg emissions from the incineration of sewage sludge based on the THg

372

concentrations of the sewage sludges in different provinces, which better represents

373

China than the emission factor given by the UNEP.43 The THg concentrations in the

374

sewage sludge are critical in this estimation. We compared the modeling results for

375

the THg concentrations in the sewage sludges from different provinces with data from

376

previous literature (Figure S9, Supporting Information). The results show that our

377

modeling results are reasonably good.

378

We updated the inventory of anthropogenic THg released into aquatic environments

379

in China in a previous study (Figure S10, Supporting Information)20 based on the

380

municipal sewage measurements in this study. The results show that 23 Mg of THg

381

was released from municipal sewage into aquatic environments (17 Mg and 6.2 Mg

382

from untreated and treated sewage, respectively), which is a decrease from the 63 Mg

383

released in 2004 (63 Mg and 0.43 Mg, respectively). Other anthropogenic sources

384

released 88 Mg of THg in 2015, which is a decreased from 97 Mg released in 2004.


Page 18 of 36

Page 19 of 36


385

These results can be attributed to the improvement in municipal sewage and industrial

386

wastewater management by the Chinese government.20, 44 In China, the government

387

suggested that municipal sewage and industrial wastewater should be treated in two

388

separate systems,20,

389

wastewater.31 The industrial wastewater in the municipal sewage system was not

390

double counted with other industrial releases in the THg estimation in our study.20 The

391

MeHg released from municipal sewage into aquatic environments also decreased

392

during this period (Figure 5c).

44

but municipal sewage still contains some industrial

393

As an important factor that has been previously ignored,10 the THg released into

394

land increased rapidly from 2001 to 2015. In total, 120 Mg of THg was released into

395

land in China in 2015, which is a 15-fold increase from 2001 (Figure 5b). This rapid

396

increase can be attributed to the increase in the percent of treated municipal sewage

397

(Figure S3, Supporting Information) and the high pollution removal efficiency of

398

MSPTs in China (Table S1, Supporting Information). The treatment ratio was 92% in

399

China in 2015, which increased from 18% in 2001.44 The THg released into the

400

atmosphere from the incineration of sewage sludge also increased rapidly from 2001

401

to 2015. East China contributed most of the THg emissions from this part during this

402

period (Figure 6d) since this region has the highest generation of sewage sludge and

403

the highest incineration percentage of sewage sludge (43% in 2015, while the other 7

404

regions ranged from 0% to 8.9%).

405

Implications. We constructed the first complete evaluation system for Hg released



406

from municipal sewage into various sinks in China based on measurement data and

407

material flow analysis. We determined that the THg released from municipal sewage

408

into the environment, which has been previously ignored or underestimated,10, 20 is a

409

substantial part of the anthropogenic THg release in China. The THg released from

410

municipal sewage into aquatic environments decreased after 2004, but the release to

411

both land and the atmosphere increased rapidly from 2001. The total THg released

412

from municipal sewage increased from 2001, but the quantities of THg released into

413

different sinks fluctuated significantly every year. This phenomenon may also occur

414

for other anthropogenic sources of Hg in China and other countries. Zhang et al.

415

explained the observed decrease in atmospheric THg based on the decline of

416

anthropogenic emissions in recent years,69 and Streets et al. determined that the

417

release of anthropogenic THg into aquatic environments and land was increasing.9, 70

418

This means that more anthropogenic THg may be accumulating in the local food web.

419

Hui et al. indicated that anthropogenic THg emissions in China may have peaked in

420

2012,10 while our study indicated that the release of anthropogenic THg into aquatic

421

environments peaked before 2004. This means that the government should pay

422

attention to the aggravation of land contaminated by Hg, such as cases in which

423

municipal sewage has been released.

424

Based on municipal sewage, we suggest further studies on the release of Hg from

425

other anthropogenic sources into the land in China should be performed in the future.

426

For example, 3,300 Tg of industrial solid waste was generated in China in 2015, and

427

only 820 Tg of industrial and municipal solid waste was generated in 2001.63 The


Page 20 of 36

Page 21 of 36


428

final fate of Hg in industrial solid waste is still unclear.44 More investigations on the

429

fate of industrial solid waste should be carried out to better understand the potential

430

levels of soil contamination in China.

431

We should also consider the role of anthropogenic MeHg release into aquatic

432

environments and croplands. Although the release of MeHg only accounted for 1.8%

433

of the THg released from municipal sewage, it can accumulate in local fish and crops,

434

such as rice, without long-range transport or methylation of inorganic Hg. Schartup et

435

al. discovered that freshwater discharge results in high levels of MeHg in Arctic

436

marine biota.16 In China, 97% of fish products were harvested from freshwater

437

environments and adjacent seas in 2015.71 Previous studies have indicated that rice

438

(when the fields are flooded) and poultry produced in Hg polluted areas in China can

439

accumulate a large amount of MeHg.32, 33 In some Hg-contaminated regions of China

440

such as Guizhou province, 95% of the daily MeHg intake was rice-dereved.32 There is

441

still a lack of evidence regarding the accumulation of MeHg in other crops and

442

livestock, and further studies need to be carried out. Therefore, we believe that the

443

MeHg released from municipal sewage and other terrestrial anthropogenic sources

444

may be a potential source for the increase in MeHg levels of biota in freshwater,

445

adjacent seas and soil, and mitigation measures should be taken.72 Furthermore, we

446

suggest that the MeHg content in the untreated sewage of MSPTs may be a potential

447

index of regional population exposure to MeHg, especially in underdeveloped regions,

448

such as Tibet, and these data can be used to protect MeHg-susceptible populations,

449

such as developing fetuses.



450

ASSOCIATED CONTENT

451

Supporting Information

452

Additional information on the eight regions in China (Figure S1), basic municipal

453

sewage data (Figures S2 and S3), uncertainty analysis (Figure S4), distribution of Hg

454

released from municipal sewage into different environments (Figures S5 to S8), fate

455

of THg in sewage sludge (Figure S9), updates on THg released from direct

456

anthropogenic sources (Figure S10), sampling information (Table S1), and

457

comparison with previous studies (Table S2).

458

ACKONWLEDGMENTS

459

The authors would like to thank the editor, reviewers, Robert P. Mason and Zofia

460

Baumann for their insightful comments and helpful discussion on the paper. This work

461

was funded by the National Natural Science Foundation of China (41630748,

462

41571130010, 41571484, 41130535, and 41471403).

463

REFERENCES

464 465 466 467 468 469 470 471 472 473

1.

Driscoll, C. T.; Mason, R. P.; Chan, H. M.; Jacob, D. J.; Pirrone, N., Mercury as a global pollutant:

sources, pathways, and effects. Environmental science & technology 2013, 47, (10), 4967-4983. 2.

Lamborg, C. H.; Hammerschmidt, C. R.; Bowman, K. L.; Swarr, G. J.; Munson, K. M.; Ohnemus,

D. C.; Lam, P. J.; Heimbürger, L. E.; Rijkenberg, M. J.; Saito, M. A., A global ocean inventory of anthropogenic mercury based on water column measurements. Nature 2014, 512, (7512), 65-68. 3.

Lavoie, R. A.; Jardine, T. D.; Chumchal, M. M.; Kidd, K. A.; Campbell, L. M., Biomagnification

of mercury in aquatic food webs: a worldwide meta-analysis. Environmental science & technology 2013, 47, (23), 13385-13394. 4.

Mason, R. P.; Sheu, G. R., Role of the ocean in the global mercury cycle. Global biogeochemical

cycles 2002, 16, (4), 1-16.


Page 22 of 36

Page 23 of 36


474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517

5.

Kocman, D.; Wilson, S. J.; Amos, H. M.; Telmer, K. H.; Steenhuisen, F.; Sunderland, E. M.;

Mason, R. P.; Outridge, P.; Horvat, M., Toward an Assessment of the Global Inventory of Present-Day Mercury Releases to Freshwater Environments. International Journal of Environmental Research and Public Health 2017, 14, (2), 138-154. 6.

Pirrone, N.; Cinnirella, S.; Feng, X.; Finkelman, R.; Friedli, H.; Leaner, J.; Mason, R.; Mukherjee,

A.; Stracher, G.; Streets, D., Global mercury emissions to the atmosphere from anthropogenic and natural sources. Atmospheric Chemistry and Physics 2010, 10, (13), 5951-5964. 7.

Nriagu, J. O.; Pacyna, J. M., Quantitative assessment of worldwide contamination of air, water

and soils by trace metals. nature 1988, 333, (6169), 134-139. 8.

Sundseth, K.; Pacyna, J. M.; Pacyna, E. G.; Pirrone, N.; Thorne, R. J., Global Sources and

Pathways of Mercury in the Context of Human Health. International journal of environmental research and public health 2017, 14, (1), 105-119. 9.

Streets, D. G.; Horowitz, H. M.; Jacob, D. J.; Lu, Z.; Levin, L.; Ter Schure, A. F.; Sunderland, E.

M., Total Mercury Released to the Environment by Human Activities. Environmental Science & Technology 2017, 51, (11), 5969-5977. 10. Hui, M.; Wu, Q.; Wang, S.; Liang, S.; Zhang, L.; Wang, F.; Lenzen, M.; Wang, Y.; Xu, L.; Lin, Z., Mercury flows in China and global drivers. Environmental science & technology 2016, 51, (1), 222-231. 11. Amos, H. M.; Jacob, D. J.; Kocman, D.; Horowitz, H. M.; Zhang, Y.; Dutkiewicz, S.; Horvat, M.; Corbitt, E. S.; Krabbenhoft, D. P.; Sunderland, E. M., Global biogeochemical implications of mercury discharges from rivers and sediment burial. Environmental science & technology 2014, 48, (16), 9514-9522. 12. Streets, D. G.; Hao, J.; Wu, Y.; Jiang, J.; Chan, M.; Tian, H.; Feng, X., Anthropogenic mercury emissions in China. Atmospheric Environment 2005, 39, (40), 7789-7806. 13. Wu, Y.; Wang, S.; Streets, D. G.; Hao, J.; Chan, M.; Jiang, J., Trends in anthropogenic mercury emissions in China from 1995 to 2003. Environmental science & technology 2006, 40, (17), 5312-5318. 14. Wu, Q.; Wang, S.; Li, G.; Liang, S.; Lin, C.-J.; Wang, Y.; Cai, S.; Liu, K.; Hao, J., Temporal Trend and Spatial Distribution of Speciated Atmospheric Mercury Emissions in China During 1978–2014. Environmental science & technology 2016, 50, (24), 13428-13435. 15. Pacyna, J. M.; Travnikov, O.; De Simone, F.; Hedgecock, I. M.; Sundseth, K.; Pacyna, E. G.; Steenhuisen, F.; Pirrone, N.; Munthe, J.; Kindbom, K., Current and future levels of mercury atmospheric pollution on a global scale. Atmospheric Chemistry and Physics 2016, 16, (19), 12495-12511. 16. Schartup, A. T.; Balcom, P. H.; Soerensen, A. L.; Gosnell, K. J.; Calder, R. S.; Mason, R. P.; Sunderland, E. M., Freshwater discharges drive high levels of methylmercury in Arctic marine biota. Proceedings of the National Academy of Sciences 2015, 112, (38), 11789-11794. 17. Sunderland, E. M.; Dalziel, J.; Heyes, A.; Branfireun, B. A.; Krabbenhoft, D. P.; Gobas, F. A., Response of a macrotidal estuary to changes in anthropogenic mercury loading between 1850 and 2000. Environmental science & technology 2010, 44, (5), 1698-1704. 18. Hammerschmidt, C. R.; Fitzgerald, W. F., Bioaccumulation and trophic transfer of methylmercury in Long Island Sound. Archives of Environmental Contamination and Toxicology 2006, 51, (3), 416-424. 19. Harada, M., Minamata disease: methylmercury poisoning in Japan caused by environmental



518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561

pollution. Critical reviews in toxicology 1995, 25, (1), 1-24. 20. Liu, M.; Zhang, W.; Wang, X.; Chen, L.; Wang, H.; Luo, Y.; Zhang, H.; Shen, H.; Tong, Y.; Ou, L., Mercury Release to Aquatic Environments from Anthropogenic Sources in China from 2001 to 2012. Environmental Science & Technology 2016, 50, (15), 8169-8177. 21. Cheng, H.; Hu, Y., Mercury in municipal solid waste in China and its control: a review. Environmental science & technology 2011, 46, (2), 593-605. 22. Feng, X.; Li, P.; Qiu, G.; Wang, S.; Li, G.; Shang, L.; Meng, B.; Jiang, H.; Bai, W.; Li, Z., Human exposure to methylmercury through rice intake in mercury mining areas, guizhou province, china. Environmental science & technology 2007, 42, (1), 326-332. 23. Chaudri, A. M.; Allain, C. M.; Badawy, S.; Adams, M. L.; McGrath, S. P.; Chambers, B. J., Cadmium content of wheat grain from a long-term field experiment with sewage sludge. Journal of environmental quality 2001, 30, (5), 1575-1580. 24. Liu, R.; Lin, Y.; Hu, F.; Liu, R.; Ruan, T.; Jiang, G., Observation of emerging photoinitiator additives in household environment and sewage sludge in China. Environmental science & technology 2015, 50, (1), 97-104. 25. Meng, X.; Venkatesan, A. K.; Ni, Y.; Steele, J. C.; Wu, L.; Bignert, A.; Bergman, Å.; Halden, R. U., Organic contaminants in Chinese sewage sludge: a meta-analysis of the literature of the past 30 years. Environmental science & technology 2016, 50, (11), 5454-5466. 26. Zeng, L.; Li, H.; Wang, T.; Gao, Y.; Xiao, K.; Du, Y.; Wang, Y.; Jiang, G., Behavior, fate, and mass loading of short chain chlorinated paraffins in an advanced municipal sewage treatment plant. Environmental science & technology 2013, 47, (2), 732-740. 27. Wang, S.; Zhang, L.; Li, G.; Wu, Y.; Hao, J.; Pirrone, N.; Sprovieri, F.; Ancora, M., Mercury emission and speciation of coal-fired power plants in China. Atmospheric Chemistry and Physics 2010, 10, (3), 1183-1192. 28. Wu, Q.; Wang, S.; Hui, M.; Wang, F.; Zhang, L.; Duan, L.; Luo, Y., New insight into atmospheric mercury emissions from zinc smelters using mass flow analysis. Environmental science & technology 2015, 49, (6), 3532-3539. 29. Ren, W.; Duan, L.; Zhu, Z.; Du, W.; An, Z.; Xu, L.; Zhang, C.; Zhuo, Y.; Chen, C., Mercury transformation and distribution across a polyvinyl chloride (PVC) production line in China. Environmental science & technology 2014, 48, (4), 2321-2327. 30. Lin, Y.; Wang, S.; Wu, Q.; Larssen, T., Material flow for the intentional use of mercury in China. Environmental science & technology 2016, 50, (5), 2337-2344. 31. NBS, China Environment Yearbook. National Bureau of Statistics (NBS): Beijing, China, 2002-2016. 32. 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), 1183-1188. 33. Yin, R.; Wei, Z.; Sun, G.; Feng, Z.; Hurley, J. P.; Yang, L.; Shang, L.; Feng, X., Mercury risk in poultry in the Wanshan Mercury Mine, China. Environmental Pollution 2017, 230, 810-816. 34. Gibbs, P.; Miskiewicz, A., Heavy metals in fish near a major primary treatment sewage plant outfall. Marine pollution bulletin 1995, 30, (10), 667-674. 35. Hicks, K. A.; Fuzzen, M. L.; McCann, E. K.; Arlos, M. J.; Bragg, L. M.; Kleywegt, S.; Tetreault, G. R.; McMaster, M. E.; Servos, M. R., Reduction of intersex in a wild fish population in response to major municipal wastewater treatment plant upgrades. Environmental science & technology 2017, 51,


Page 24 of 36

Page 25 of 36


562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605

(3), 1811-1819. 36. Du, P.; Li, K.; Li, J.; Xu, Z.; Fu, X.; Yang, J.; Zhang, H.; Li, X., Methamphetamine and ketamine use in major Chinese cities, a nationwide reconnaissance through sewage-based epidemiology. Water research 2015, 84, 76-84. 37. Zhang, Q.; Ying, G.; Pan, C.; Liu, Y.; Zhao, J., Comprehensive evaluation of antibiotics emission and fate in the river basins of China: source analysis, multimedia modeling, and linkage to bacterial resistance. Environmental science & technology 2015, 49, (11), 6772-6782. 38. Emmerton, C. A.; Graydon, J. A.; Gareis, J. A.; St. Louis, V. L.; Lesack, L. F.; Banack, J. K.; Hicks, F.; Nafziger, J., Mercury export to the Arctic Ocean from the Mackenzie River, Canada. Environmental science & technology 2013, 47, (14), 7644-7654. 39. Buck, C. S.; Hammerschmidt, C. R.; Bowman, K. L.; Gill, G. A.; Landing, W. M., Flux of Total Mercury and Methylmercury to the Northern Gulf of Mexico from US Estuaries. Environmental science & technology 2015, 49, (24), 13992-13999. 40. Hammerschmidt, C. R.; Fitzgerald, W. F.; Lamborg, C. H.; Balcom, P. H.; Tseng, C.-M., Biogeochemical cycling of methylmercury in lakes and tundra watersheds of Arctic Alaska. Environmental science & technology 2006, 40, (4), 1204-1211. 41. Shen, H.; Tao, S.; Chen, Y.; Ciais, P.; Güneralp, B.; Ru, M.; Zhong, Q.; Yun, X.; Zhu, X.; Huang, T., Urbanization-induced population migration has reduced ambient PM2. 5 concentrations in China. Science Advances 2017, 3, (7), e1700300. 42. Wang, R.; Tao, S.; Wang, W.; Liu, J.; Shen, H.; Shen, G.; Wang, B.; Liu, X.; Li, W.; Huang, Y., Black carbon emissions in China from 1949 to 2050. Environmental science & technology 2012, 46, (14), 7595-7603. 43. AMAP/UNEP, Technical Background Report for the Global Mercury Assessment 2013. Arctic Monitoring and Assessment Programme 2013. 44. NBS, China Environmental Statistical Yearbook. National Bureau of Statistics (NBS): Beijing, China, 2002-2016. 45. Allesch, A.; Brunner, P. H., Material Flow Analysis as a Tool to improve Waste Management Systems: The Case of Austria. Environmental science & technology 2016, 51, (1), 540-551. 46. Brunner, P. H.; Rechberger, H., Handbook of Material Flow Analysis: For Environmental, Resource, and Waste Engineers, Second Edition. In CRC Press, Taylor & Francis Group: 2016. 47. Lindberg, S.; Price, J., Airborne emissions of mercury from municipal landfill operations: a short-term measurement study in Florida. Journal of the Air & Waste Management Association 1999, 49, (5), 520-532. 48. Balogh, S.; Liang, L., Mercury pathways in municipal wastewater treatment plants. Water, Air, and Soil Pollution 1995, 80, (1-4), 1181-1190. 49. Balogh, S. J.; Nollet, Y. H., Mercury mass balance at a wastewater treatment plant employing sludge incineration with offgas mercury control. Science of the total environment 2008, 389, (1), 125-131. 50. Duan, Y.; Zhao, C.; Wang, Y.; Wu, C., Mercury emission from co-combustion of coal and sludge in a circulating fluidized-bed incinerator. Energy & Fuels 2009, 24, (1), 220-224. 51. Hu, D.; Zhang, W.; Chen, L.; Chen, C.; Ou, L.; Tong, Y.; Wei, W.; Long, W.; Wang, X., Mercury emissions from waste combustion in China from 2004 to 2010. Atmospheric environment 2012, 62, 359-366. 52. McInnes, G., Atmospheric Emission Inventory Guidebook: A Joint EMEP/CORINAIR Production.



606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649

European Environment Agency: 1996. 53. Liu, M.; Chen, L.; Wang, X.; Zhang, W.; Tong, Y.; Ou, L.; Xie, H.; Shen, H.; Ye, X.; Deng, C., Mercury Export from Mainland China to Adjacent Seas and Its Influence on the Marine Mercury Balance. Environmental science & technology 2016, 50, (12), 6224-6232. 54. Wang, S.; Xing, D.; Wei, Z.; Jia, Y., Spatial and seasonal variations in soil and river water mercury in a boreal forest, Changbai Mountain, Northeastern China. Geoderma 2013, 206, 123-132. 55. 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 2012, 19, (1), 105-112. 56. Zheng, W.; Kang, S.; Feng, X.; Zhang, Q.; Li, C., Mercury speciation and spatial distribution in surface waters of the Yarlung Zangbo River, Tibet. Chinese Science Bulletin 2010, 55, (24), 2697-2703. 57. Gbondo-Tugbawa, S. S.; McAlear, J. A.; Driscoll, C. T.; Sharpe, C. W., Total and methyl mercury transformations and mass loadings within a wastewater treatment plant and the impact of the effluent discharge to an alkaline hypereutrophic lake. Water research 2010, 44, (9), 2863-2875. 58. Bodaly, R. D.; Rudd, W.; Flett, R. J., Effect of urban sewage treatment on total and methyl mercury concentrations in effluents. Biogeochemistry 1998, 40, (2-3), 279-291. 59. da Silva Oliveira, A.; Bocio, A.; Trevilato, T. M. B.; Takayanagui, A. M. M.; Domingo, J. L.; Segura-Muñoz, S. I., Heavy metals in untreated/treated urban effluent and sludge from a biological wastewater treatment plant. Environmental Science and Pollution Research-International 2007, 14, (7), 483-489. 60. Mao, Y.; Cheng, L.; Ma, B.; Cai, Y., The fate of mercury in municipal wastewater treatment plants in China: significance and implications for environmental cycling. Journal of hazardous materials 2016, 306, 1-7. 61. Zhao, J.; Jiang, Y.; Yan, B.; Wei, C.; Zhang, L.; Ying, G., Multispecies acute toxicity evaluation of wastewaters from different treatment stages in a coking wastewater‐treatment plant. Environmental toxicology and chemistry 2014, 33, (9), 1967-1975. 62. Zhao, H.; Li, X.; Wang, X.; Tian, D., Grain size distribution of road-deposited sediment and its contribution to heavy metal pollution in urban runoff in Beijing, China. Journal of Hazardous Materials 2010, 183, (1), 203-210. 63. NBS, China Statistical Yearbook. National Bureau of Statistics (NBS): Beijing, China, 2002-2016. 64. Liu, X.; Sheng, H.; Jiang, S.; Yuan, Z.; Zhang, C.; Elser, J. J., Intensification of phosphorus cycling in China since the 1600s. Proceedings of the National Academy of Sciences 2016, 113, (10), 2609-2614. 65. Sallon, S.; Dory, Y.; Barghouthy, Y.; Tamdin, T.; Sangmo, R.; Tashi, J.; Yangdon, S.; Yeshi, T.; Sadutshang, T.; Rotenberg, M., Is mercury in Tibetan Medicine toxic? Clinical, neurocognitive and biochemical results of an initial cross-sectional study. Experimental Biology and Medicine 2017, 242, (3), 316-332. 66. Ernst, E.; Coon, J. T., Heavy metals in traditional Chinese medicines: a systematic review. Clinical Pharmacology & Therapeutics 2001, 70, (6), 497-504. 67. 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. 68. Tian, H.; Gao, J.; Lu, L.; Zhao, D.; Cheng, K.; Qiu, P., Temporal trends and spatial variation


Page 26 of 36

Page 27 of 36


650 651 652 653 654 655 656 657 658 659 660 661 662 663

characteristics of hazardous air pollutant emission inventory from municipal solid waste incineration in China. Environmental science & technology 2012, 46, (18), 10364-10371. 69. Zhang, Y.; Jacob, D. J.; Horowitz, H. M.; Chen, L.; Amos, H. M.; Krabbenhoft, D. P.; Slemr, F.; Louis, V. L. S.; Sunderland, E. M., Observed decrease in atmospheric mercury explained by global decline in anthropogenic emissions. Proceedings of the National Academy of Sciences 2016, 113, (3), 526-531. 70. Streets, D. G.; Lu, Z.; Levin, L.; ter Schure, A. F.; Sunderland, E. M., Historical releases of mercury to air, land, and water from coal combustion. Science of The Total Environment 2018, 615, 131-140. 71. CMA, China Fisheries Statistical Yearbook. China Ministry of Agriculture (CMA): Beijing, China, 2016. 72. Jonsson, S.; Skyllberg, U.; Nilsson, M. B.; Lundberg, E.; Andersson, A.; Björn, E., Differentiated availability of geochemical mercury pools controls methylmercury levels in estuarine sediment and biota. Nature Communications 2014, 5, (5), 4624-4633.

664



665

Figure 1. Locations of the municipal sewage treatment plants selected for this study. The

666

black line is the Chinese geographic “Hu Huanyong Line” (reflects the different levels of

667

human activities in different regions in China). The information on the distribution of the

668

Chinese population is from the census information for each region (http://data.cnki.net/).

669

The South China Sea is not included in the map.

670

Figure 2. THg (a) and MeHg (b) concentrations in the influent (untreated) and effluent

671

(treated) sewage of municipal sewage treatment plants in different provinces in China. It

672

should be noted that the scales for the influent and effluent for both THg and MeHg

673

concentrations are different, since the effluent is significantly smaller than the influent.

674

Figure 3. The relationship between amount of THg and MeHg and the population

675

distribution in China. a is the relationship of the THg concentrations between the sewage

676

influent (untreated) and effluent (treated); b is the relationship of the MeHg concentrations

677

between the sewage influent (untreated) and effluent (treated); c and d are the

678

relationships of the THg and MeHg released with respect to the population distribution,

679

respectively. Shaded areas in the figures are the 95% confidence intervals.

680

Figure 4. Distributions of THg and MeHg released from municipal sewage in China in

681

2015. a and b are the release of THg and MeHg, respectively; c and d are the contribution

682

per capita of THg and MeHg in the different provinces, respectively.

683

Figure 5. THg and MeHg material flow analyses of municipal sewage from the source to

684

various sinks in China. a is the material flow analyses in 2015; b and c are the


Page 28 of 36

Page 29 of 36


685

uncertainties of the THg and MeHg released from municipal sewage from 2001 to 2015,

686

respectively; d and e are the trends of THg and MeHg received by different sinks from

687

2001 to 2015, respectively. In figure a, brown is the source, green is the temporary

688

storage and blue is the sink. Urban areas can also be sinks in this study.

689

Figure 6. Trends in the release of THg from municipal sewage into aquatic environments,

690

land and the atmosphere in different regions of China from 2001 to 2015. Details for

691

different regions and land sub-sinks in different regions are provided in Figure S1 and S9

692

(Supporting Information), respectively.



THg

THg (Mg/yr)

80% 50% 20%

Urban

?

17

?

15

Decreasing

0 2001

2015

63

80% 50% 20%

Water

?

Municipal sewage

MeHg 23

MeHg (kg/yr)

280

Increasing 0 360

160

MeHg (kg/yr)

110

THg (Mg/yr)

210

Land

Air

Year

Abstract Art


Page 30 of 36

Page 31 of 36


± Heilongjiang

40°0'0"N

Jilin

Beijing Xinjiang

Liaoning

Hebei Gansu

Inner Mongolia

Tianjin

Shanxi Ningxia Shandong

Qinghai 30°0'0"N

Jiangsu

Henan

Shannxi

Tibet

Shanghai Anhui Hubei

Chongqing

Zhejiang

Sichuan Jiangxi Hunan

Fujian

Guizhou Sample size

Taiwan 20°0'0"N

1

3

Yunnan

>5

Guangxi

Guangdong

Unit: population/km2

0

600 90°0'0"E

>1200 100°0'0"E

Figure 1


Hainan 110°0'0"E

0

500

1,000 Kilometers 120°0'0"E


a

Page 32 of 36

b Heilongjiang Beijing Tianjin

Beijing Tianjin

Liaoning Heilongjiang

Liaoning

Gansu

Shanxi

Henan

Influent (μg/L)

1

0

0

THg

Effluent (μg/L)

Sichuan Hubei Chongqing

10

Hunan Yunnan

Jiangsu Shannxi

Shanghai

Tibet

20 Fujian

Guangxi Guangdong

Henan

Shanghai

Sichuan Hubei Chongqing

Zhejiang

10

0

0

MeHg

Figure 2


Effluent (ng/L)

Shannxi

Shandong

Qinghai

Jiangsu

Tibet

Hebei

Ningxia

Shanxi

Shandong

Influent (ng/L)

Qinghai

Gansu

Hebei

Ningxia

Zhejiang

Hunan Fujian Yunnan

Guangxi Guangdong

2 a. P6.4


a

Urban

210

17(?)

River

160 (280)

12(18)

Municipal sewage

Industry

THg release (Mg/yr)

THg (MeHg) flow Unit: Mg/yr (kg/yr)

150 (260)

140

50% 20%

70

70

0 2001

20% 120

120

0 2001

Landscape

Building material

River Lake Ocean Landfill

48

Cropland Incineration Dumping

24

Building material Reuse

26(?)

16(?)

0

2015 Year

d

140 (220)

Sewage sludge

240

50%

72

Sewage treatment plant

Ocean

0

2015

80% 240

Year

THg release (Mg/yr)

Lake

360

c 80%

140

Municipal services 0.74 (4.3)

360

210

b MeHg release (kg/yr)

Page 35 of 36

Emission

0 120

Incineration

15(?)

23(63) Aquatic environment

Land

Atmosphere

MeHg release (kg/yr)

Cropland

26(?)

Landfill

0.82(?)

e

80

River Lake Ocean

40

Reuse

0 2001

Figure 5


2008 Year

2015


THg release (Mg/yr)

60

40

16

20

8

0

0

48

THg release (Mg/yr)

24

Total release

12

Land

32

8

16

4

0 2001

2008 Year

2015

Aquatic environment

Atmosphere

0 2001

2008 Year

2015

North

Northeast

East

Central

South

Southwest

Northwest

Tibetan Region

Figure 6


Page 36 of 36

Increases of Total Mercury and Methylmercury Releases from

Recommend Documents