Haloacetic acids in swimming pool and spa water in ... - Springer Link

Front. Environ. Sci. Eng. 2014, 8(6): 820–824 DOI 10.1007/s11783-014-0712-7

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Haloacetic acids in swimming pool and spa water in the United States and China Xiaomao WANG1, Garcia Leal M I2, Xiaolu ZHANG1, Hongwei YANG1, Yuefeng XIE (✉)1,3 1 School of Environment, State Key Joint Laboratory of Environmental Simulation and Pollution Control, Tsinghua University, Beijing 100084, China 2 Department of Chemical Engineering, University of Cantabria, Avenida de los Castros s/n 39005 Santander, Cantabria, Spain 3 Environmental Engineering Program, The Pennsylvania State University, 777 West Harrisburg Pike, Middletown, PA 17057, USA

© Higher Education Press and Springer-Verlag Berlin Heidelberg 2014

Abstract The objective of this study is to investigate the occurrence of haloacetic acids (HAAs), a group of disinfection byproducts, in swimming pool and spa water. The samples were collected from six indoor pools, six outdoor pools and three spas in Pennsylvania, the United States, and from five outdoor pools and nine indoor pools in Beijing, China. Five HAAs (HAA5), including monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid, and dibromoacetic acid were analyzed. Total chlorine, pH and total organic carbon concentration were analyzed as well. Results indicated that the levels of HAA5 in swimming pools and spas in the United States ranged from 70 to 3980 µg$L–1, with an arithmetic average at 1440 µg$L–1 and a median level at 1150 µg$L–1. These levels are much higher than the levels reported in chlorinated drinking water and are likely due to organic matters released from swimmers’ bodies. The levels of HAA5 in swimming pools in China ranged from 13 to 332 µg$L–1, with an arithmetic average at 117 µg$L–1 and a median level at 114 µg$L–1. The lower HAA levels in swimming pools in China were due to the lower chlorine residuals. Results from this study can help water professionals to better understand the formation and stability of HAAs in chlorinated water and assess risks associated with exposures to HAAs in swimming pools and spas. Keywords chlorination, disinfection byproduct, haloacetic acid, swimming pool, trihalomethane

Received January 8, 2014; accepted April 2, 2014 E-mail: [email protected]

1

Introduction

Chlorination is the most common process for disinfection of public swimming pools [1–3]. For effective disinfection in swimming pools, chlorine residuals of 1–3 mg$L–1 are recommended. For outdoor swimming pool disinfection, stabilized chlorine compounds or chlorinated isocyanurates (e.g. trichloroisocyanuric acid) are widely used [4]. Chlorinated isocyanurates dissociate in water to release free chlorine in equilibrium with cyanuric acid. Alternative disinfectants, including bromine, ozone and ultraviolet, are also used for swimming pool disinfection. Although chlorination is the most common disinfection method for water disinfection, various disinfection byproducts (DBPs) have been identified in chlorinated water and swimming pools [3,5,6]. Trihalomethanes (THMs), including chloroform, bromodichloromethane, dibromochloromethane, and bromoform, are regulated in chlorinated drinking water in many countries [7]. The levels of THMs in swimming pools reported showed a tendency of wide variation [8]. Sandel [9] examined 114 residential pools in the United States (US) and reported the average concentration of chloroform at 67 µg$L–1 with a maximum concentration at 313 µg$L–1. Fantuzzi et al. [10] examined five indoor swimming pools in Italy and reported the average THM concentration at 40 µg$L–1 in swimming pools. In a study of eight indoor swimming pools in London, the United Kingdom [11], the arithmetic mean and geometric mean were reported at 132 and 125 µg$L–1, respectively. The concentrations of THMs in swimming pools in Thailand were reported in the range of 26 and 65 µg$L–1 [12]. Thacker et al. [13] also reported THMs in the range of 90 and 355 µg$L–1 in swimming pools in India. A recent survey of 15 indoor swimming pools in Canada revealed that the chloroform concentrations ranged from 12.9 to 215 µg$L–1 with the mean value at 55.2 µg$L–1

Xiaomao WANG et al. Haloacetic acids in swimming pool water

[14]. Researchers from the same group found that the total THM levels in outdoor pools were higher than that in indoor pools (97.9 vs. 63.7 µg$L–1 in average) [15]. The variation of THM concentration in swimming pool water can be affected by the number of swimmers in the pool, human body substances, chlorine dose, bromide content, pH, temperature, and season [16,17]. The impact of THMs in swimming pools on human health was studied as well [14,18,19]. Haloacetic acids (HAAs) are another group of DBPs commonly detected in chlorinated drinking water. Five HAAs, commonly referred as HAA5 (monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid, and dibromoacetic acid), are also regulated for drinking water in the US with a maximum contaminant level at 60 µg$L–1 [7]. There is limited information on HAA levels in swimming pools. In a study of 15 indoor and 3 outdoor swimming pools in Germany, average concentrations of dichloroacetic acid were reported at 5.6 and 120 µg$L–1in indoor and outdoor pools, respectively [8]. The average concentration of dichloroacetic acid in three indoor pools in the US was reported at 419 µg$L–1 [8]. In another study in Germany, both dichloroacetic acid and trichloroacetic acid were reported [8]. The mean dichloroacetic acid levels were reported at 23, 8.8 and 132 µg$L–1 in indoor pools, hydrotherapy, and outdoor pools, respectively. The mean trichloroacetic acid levels were reported at 42, 15, and 249 µg$L–1 in indoor pools, hydrotherapy, and outdoor pools, respectively. For dichloroacetic acid, there is a noticeable difference between the results of studies from Germany and the United States. A recent survey of 54 indoor and outdoor swimming pools in Canada showed that the HAA levels were substantially higher than the total THM levels [15]. The average nine HAA levels were 808 and 413 µg$L–1 in outdoor and indoor pools, respectively. Exposure studies indicated that HAAs in swimming pools got into the swimmers’ bodies primarily by accidental ingestion [20]. This study was conducted to investigate the occurrence and speciation of HAAs in 15 swimming pools and spas in Pennsylvania, the US and 14 swimming pools in Beijing, China. Compared with that in industrial countries, little was known about the DBP levels in swimming pools in China. The effects of water quality parameters on HAA formation and stability are explored as well.

2

Material and methods

2.1

Sample collection

Water samples were collected directly from swimming pools and spas using 250 mL amber glass bottles. These bottles were filled to the top, tightly sealed with screw caps with Teflon lined septa. The bottles were taken to the

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laboratory within 4 h and were transferred to 40 mL glass vials. For HAA samples, ammonium chloride (NH4Cl) or ascorbic acid was added to the vials to quench the chlorine residual. Then these vials were sealed headspace free with screw caps with Teflon lined septa and stored at 4°C immediately. Sample extractions were done within 14 days. Extracts were kept in the freezer until the analysis with a maximum storage time of 14 days. For total organic carbon (TOC) analysis, the samples were transferred to 40 mL glass vials, acidified with phosphoric acid (H3PO4) to pH£2, and stored at 4°C for no longer than 30 days before the analysis. Total chlorine and pH were measured immediately when the samples were brought to the laboratory. 2.2

Sample analysis

HAA concentrations were determined using the USEPA Method 552.3 with a few modifications [21]. The analytical procedure involves methyl tertiary butyl ether (MTBE) extraction, acid methanol derivation, and gas chromatography analysis. The gas chromatographs used in the study were both equipped with a split/splitless injector, a liquid autosampler, an electron capture detector, and a DB-1701 capillary column. TOC was analyzed using an OI Analytical 1010 TOC analyzer or Shimadzu TOC-V CPH TOC analyzer. The pH was determined with a Thermo Orion pH meter. Total chlorine was measured with a colorimeter HACH DR 890 (0–2 mg$L–1) or an electric chlorine analyzer (0.01 L, Loveland, USA).

3

Results and discussion

3.1 HAA levels in swimming pools and spas in the United States

A total of 15 swimming pools and spas, including 6 outdoor and 6 indoor pools and 3 spas, were sampled and analyzed for HAAs and other water quality parameters, including pH, total organic carbon (TOC), total chlorine. Results for these swimming pools and spas are shown in Table 1. Eight of these samples were taken from hotels around the Pennsylvania State University campus, one from a college and six from private homes. The median values for TOC and total chlorine were 3.5 and 4.0 mg$L–1, respectively. Most of the total chlorine (except when chlorinated isocyanurates were used) was expected in the form of free chlorine. The levels of HAA5 ranged from 70 to 3980 µg$L–1with an arithmetic average at 1440 µg$L–1 and a median level at 1150 µg$L–1. This average level for HAA5 is 24 times of the maximum contaminant level of 60 µg$L–1 regulated by the US Environmental Protection Agency in drinking water. All 15 samples had HAA levels higher than 60 µg

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Table 1 Analytical results of the 15 swimming pools and spas in the United States category

pool number

pH

TOC/(mg$L–1)

outdoor

1

7.1

2.0

9.8

1330

930

2430

2

7.1

1.1

10.0

450

440

890

3

7.6

1.3

1.4

350

450

800

4

6.9

8.5

8.0

310

1140

1450

5

7.3

0.9

10.6

480

370

950

6

7.4

0.9

6.6

1280

750

2130

7

7.1

1.3

4.0

50

20

70

8

7.5

3.5

1.5

590

290

780

indoor

spa

Cl2AA /(µg$L–1) Cl3AA /(µg$L–1)HAA5 /(µg$L–1)

9

7.7

5.3

2.7

1010

2970

3980

10

7.5

6.6

5.6

2040

880

2920

11

7.0

2.9

3.6

530

1110

1680

12

7.4

8.4

3.1

140

70

250

13

7.7

9.3

2.3

750

530

1360

14

7.6

3.7

0.9

550

420

1150

15

7.4

11.3

4.3

50

40

690

$L–1. The average HAA5 levels for outdoor pools, indoor pools and spas were 1440, 1610, and 1070 µg$L–1, respectively. Dibromoacetic acid and bromochloroacetic acid were observed as the predominant dihaloacetic acids in Spa 3, as shown in Table 1. This is due to the fact that bromine containing disinfectants were used in the spa. The apparent lower level of HAA5 in Spa 3 is likely due to the formation of brominated analogs for trihaloacetic acids. Several brominated trihaloacetic acids, including bromodichloroacetic acid, chlorodibromoacetic acid, and tribromoacetic acid, were not included in the HAA analysis. 3.2

total chlorine/(mg$L–1)

HAA levels in swimming pools in China

A total of 14 swimming pools, including 5 outdoor and 9 indoor swimming pools, were sampled and analyzed for HAAs and other water quality parameters. Results for these swimming pools are shown in Table 2. Two of the outdoor pools were located on university campuses, while the remaining three were public swimming pools. Five of the indoor pools were located on university campuses, while the remaining four indoor pools were in hotels. The median values for TOC and total chlorine were 7.6 and 0.9 mg$L–1, respectively. When total chlorine concentration was low, most of the total chlorine was expected in the form of combined chlorines. The levels of HAA5 ranged from 13 to 332 µg$L–1 with an arithmetic average at 117 µg$L–1 and a median level at 114 µg$L–1. The HAA levels in the swimming pools were much higher than that in the drinking water used to refill the pools (data not shown). Samples from 12 out of the 14 swimming pools had HAA levels higher than 60 µg$L–1.

However, sample from Pool 8 had an HAA5 level as low as 13 µg$L–1. It is a university indoor swimming pool that used trichloroisocyanuric acid as the disinfecting agent. Sample from Pool 11 had an HAA5 level at 59 µg$L–1. It is an indoor pool in a hotel, which used chlorine dioxide as the disinfectant. Dichloroacetic acid and trichloroacetic acids were the dominant HAA species in all samples, indicating that bromide ion concentrations were low in the pool water. No bromine containing disinfectants were used for disinfection of the swimming pools. In most samples, bromochloroacetic acid was the dominant brominated HAA species. The median HAA5 levels for outdoor and indoor pools were 113 and 114 µg$L–1, respectively. The difference of other water parameters between outdoor and indoor pools was also marginal. The median values for TOC and total chlorine were 9.2 and 1.1 mg$L–1, respectively, for outdoor pool samples, and 6.1 and 0.8 mg$L–1, respectively, for indoor pool samples. 3.3

Correlation of HAA levels with water parameters

DBPs are generated from reactions between organic matter in water and the disinfectant. Drinking water contains natural organic matter from source water. The variation of DBP concentrations in drinking water depend on many factors, including natural organic matter, chlorine dose, bromide content, pH, temperature, and pre- and posttreatment processes [5]. Poor correlation could be established between the HAA5 levels and the natural organic matter concentrations (as TOC or UV254) in drinking water based on the Information Collection Rule data released by USEPA [22].

Xiaomao WANG et al. Haloacetic acids in swimming pool water

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Table 2 Analytical results of the 14 swimming pools in China category

pool number

pH

TOC/(mg$L–1)

total chlorine/(mg$L–1)

outdoor

1

8.1

9.2

1.1

2

7.9

12.6

3

7.8

13.0

4

8.3

5 6

indoor

Cl2AA /(µg$L–1) Cl3AA /(µg$L–1) HAA5 /(µg$L–1) 55

40

113

3.9

68

50

147

3.1

195

98

332

3.2

0.3

44

33

89

8.3

N.D.

0.3

44

40

99

7.7

2.7

1.1

35

90

128

7

8.0

3.3

1.1

40

74

123

8

7.4

5.0

0.2

5

6

13

9

8.3

6.1

0.8

60

60

121

10

7.6

16.2

0.8

28

84

114

11

7.0

20

0.6

32

18

59

12

8.5

12.8

2.0

37

30

70

13

8.2

4.7

1.0

50

47

133

14

7.2

27.2

0.6

22

70

92

Swimming pool water contains organic matters that not only from source water (i.e. drinking water) but also from swimmers’ bodies. Organic matter from swimmer bodies includes sweat, urine, mucus, skin particles, hair, lotion, cosmetics and sun screen. No correlation was observed between HAA concentrations and total organic carbon contents in the swimming pools and spas either in the US or in China. In fact, the swimming pools in China had much higher TOC levels than that in the US, but the former had much lower HAA levels. Because of much higher DBP levels, especially HAAs, in swimming pools and spas than in chlorinated drinking water, the source water, including both groundwater and surface water, has little influence on DBP levels in swimming pools and spas. Levels of HAA5 in water used to refill these swimming pools and spas were generally less than 60 µg$L–1 and have little impact on the overall level of HAAs in swimming pools and spas. Algae growth is a common issue in outdoor swimming pools. Cells and extracellular organic matter from algae are known DBP precursors. Similary high HAAs levels in both indoor and outdoor swimming pools indicated that algae growth is not the main contributor to HAA formation in swimming pools. Main contribution to HAA precursors likely comes from swimmers bodies, including sweat, urine, mucus, skin particles, hair, lotion, and cosmetics [23]. Further studies are needed to correlate number of swimmers to HAA levels or investigate the HAA formation from human body substances and cosmetics. No correlation was observed between HAA concentrations and total chlorine residual in swimming pools and spas. However, the disinfectant type had substantial effect on HAA levels. Effect of using chlorinated isocyanurates

in reducing HAA concentrations was observed in the swimming pools in both the US and China. Disinfection by chloramines would reduce HAA formation in swimming pools and spas, as that occurred in drinking water. Chloramination could be the predominant disinfection pattern in the swimming pools in China in which relatively low chlorine residuals were maintained. Swimmers release ammonium into the swimming pools and spas by sweat, urea and etc. It may explain why the average levels for HAA5 in the swimming pools in China were substantially lower than that in the swimming pools and spas in the United States. In comparison to THM values reported by others, a much higher HAA level was obtained for the swimming pools and spas in the United States in this study. As for the swimming pools in China investigated, the HAA levels were also substantially higher than the respective THM levels. This may be due to the fact that THMs are volatile organics which can be easily transferred into atmosphere. However, HAAs are presented as nonvolatile acetates in the pH range for swimming pools and spas. HAAs are a group of easily biodegradable disinfection byproducts and could undergo biological degradation in chlorinated drinking water distribution systems due to biofilms inside distribution pipes [5]. However, swimming pools and spas contain chloramines residual because of ammonium released by swimmers. Chloramine residual inhibits biological degradation of HAAs. There is no regulation for DBPs in swimming pools and spas. However, swimmers could be exposed to DBPs via ingestion, skin absorption and inhalation. Because of very high HAA levels in swimming pool water and spas, further study is needed to better assess the health impact of HAAs in swimming pool water and spas. Studies are also needed

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to better understand the HAA formation, especially HAA precursors, and HAA stability in swimming pools and spas. 9.

4

Conclusions 10.

The average levels for HAA5 in the swimming pools and spas were 1440 and 117 µg$L–1 in the US and in China, respectively. The HAA levels were substantially higher than the respective THM levels. The high levels of HAAs in swimming pools and spas are likely due to the human body substances. The lower HAA levels in the swimming pools in China might be due to the lower chlorine residuals compared with that in the swimming pools and spas in the United States. The effects of source water and algae growth on HAA formation were not observed. Because of extremely high HAA levels in swimming pool and spa water, further study is needed to better assess the health impact of HAAs in swimming pools and spas.

11.

12.

13.

14. Acknowledgements This research was supported by the National Natural Science Foundation of China (Grant No. 51290284) and Ministry of Education and Science of Spain.

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