Emission gas from cooling tower. Cl* + Cl* Cl 2. 1 st : only a fraction of chlorine that is added to cooling tower can be emitted into the atmosphere

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1 D.G.Steyn and S.T. Rao (eds). Air pollution Modelling and Its Application XX, 237pp DOI 10,1007/ , Springer Science + Business Media B.V.2010 Emission gas from cooling tower 1 st : only a fraction of chlorine that is added to cooling tower can be emitted into the atmosphere 2 nd : chlorine emissions from cooling towers are primarily emitted as HOCl, not as Cl 2 Cl 2 HOCl hv hv Cl* + Cl* Cl* + HO* Both Cl 2 and hypochlorus acid (HOCl) can undergo photolysis to produce chlorine radical which can enhance chemical production of O 3 Photolysis rate of Cl 2 is about 8 times faster than that of HOCl (9.0 hr -1 for Cl 2 vs. 1.1 hr -1 for HOCl at typical summer noon)

2 Chlorine Gas Inhalation Human Clinical Evidence of Toxicity and Experience in Animal Models Carl W. White1 and James G. Martin2 National Jewish Health and University of Colorado at Denver Health Sciences Center, Denver, Colorado; and 2McGill University, Montreal, Quebec, Canada Thus, the forms of chlorine involved in respiratory toxicity are not limited to chlorine gas (Figure 1), but also can include hypochlorous acid, chlorine dioxide, and chloramine. In fact, since chlorine gas is moderately water soluble, it can form hypochlorous acid and hydrochloric acid as it dissolves into airway surface liquid when contacting mucosal surfaces and airways (Figure 2). Workplace exposure limits for chlorine include a short-term exposure limit for up to 15-minute exposures not to exceed 1 ppm (2.9 mg/m-3). That for a long-term exposure limit is for up to 6-hour exposures not to exceed 0.5 ppm (1.5 mg/m-3). Levels of 0.3 ppm are associated with odor perception, levels of 1 2 ppm are burdensome and irritating, and those at 2 3 ppm are annoying (13). The workplace exposure limits are of interest, since the WHO Task Group proposed that ambient levels of chlorine be about ppm (0.1 mg/m-3) to protect the general population from sensory irritation, and significant reduction in ventilatory capacity Ref: PROCEEDINGS OF THE AMERICAN THORACIC SOCIETY VOL pp 257~263

4 Chlorine source VOC source

5 Measuring site HALC: Aldine site C35C: Clinton site

6 Emission Inventory of Atomic Chlorine Precursors in southeastern Texas Molecular chlorine emission Kg/day Remark Industrial point sources 650 Data : Toxic Release Inventory Cooling tower 6,426 Swimming pools 4, kg/day/cooling tower * 350 cooling tower 2m/u water 1.44 MGD (227 ton/hr) 3 flash-off fraction: ,200 kg: NaOCl/day in 11 counties (2 gal/naocl/pool/week) kg: mass transfer coefficient for HOCl: μg m -2 mim ,000 kg: 50 m 3, 2ppm, 150,000 pools Reactions of sea salt aerosol 1.6 Tap water use, etc - Total ~12 ton

7 Results from smog chamber experiments

8 Summary of results from smog chamber experiments Chlorine (ppb c ) Initial NO (ppb v ) Initial TVOC (ppb c ) O 3 Maximum (ppb v ) , , ) Injection of chlorine into the simulated air mass in the smog chamber resulted in a dramatic increase in ozone production 2) The effects of chlorine on ozone production were rapid, occurring in approximately the first 15 minutes

9 Concentration (pptv) δ Max Ozone (ppbv) remark HOCl 300 ~3.2 Equal amount of Cl 2 (mole basis) 600 ~6.2 Equal amount of Cl 2 (mass basis) Cl ~4.7 This mode run was performed with prescribed initial conditions for urban conditions ub.epa.gov%2fsi%2fsi_public_file_download.cfm%3fp_download_id%3d495748&ei=fll4ueguhiygiqecmodabq&usg=afqjc NGVGhfrT6Bw7u97qr9pOf2jr4TdKg&sig2=OCZZcFDfR3m6JzGaEl_VLQ&bvm=bv ,d.aGc&cad=rjt

10 Modeling the Effect of Chlorine Emissions on Ozone Levels over the Eastern United States GOLAM SARWAR AND PRAKASH V. BHAVE* Atmospheric Modeling Division, National Exposure Research Laboratory, U.S. Environmental Protection Agency, Research TrianglePark, North Carolina (Manuscript received 15 February 2006, in final form 10 October 2006) 1) This paper presents model estimates of the effect of chlorine emissions on atmospheric ozone concentrations in the eastern United States. 2) Chlorine sources: anthropogenic molecular chlorine emissions, hypochlorous acid emissions from cooling towers and swimming pools, and chlorine released from sea-salt aerosols. 3) Chlorine emissions: The daily maximum 1-h ozone concentrations increased by up to 12 parts per billion by volume (ppbv) in the Houston area and 6 ppbv in the New York New Jersey area. 4) Chlorine emissions and chemistry enhanced the volatile organic compound oxidation rates and, thereby, increased the ozone production rate.

11 울산오존 이산화황농도전국최고 온산화산리는환경기준초과까지 미세먼지는줄어 ( 일 ) 20:41:17 정재환 (hani@ulsanpress.net) 국립환경과학원측정 울산지역대기중미세먼지농도는감소했지만오존과이산화황의농도는전국 7 대도시에서높은수준인것으로조사됐다. 23 일국립환경과학원이미세먼지등 7 개대기오염물질에대해측정분석한자료에따르면지난해울산의미세먼지농도는 48 μg / m3로나타났다. 이는 10 년전인 2001 년 55 μg / m3에비해크게감소한것으로, 전년도인 2009 년 49 μg / m3에이어 2 년연속으로연간대기환경기준 (50 μg / m3 ) 을달성했다. 미세먼지감소원인으로는황사강도의감소, 기상특성의변화에따른지역배출원의영향감소, 울산시의미세먼지저감대책추진등이영향을미친것으로보인다. 반면울산지역오존의연평균농도는 0.023ppm 으로 10 년전 0.020ppm 보다 0.003ppm 이증가했다. 오존은도시생활을하면서화학반응을일으켜발생하는 2 차오염원으로, 자동차가늘고도시빌딩이더많아지면서발생량이늘어난것으로추정된다. 지난해이산화질소연평균농도 (0.023ppm) 는 10 년전 0.022ppm 보다 0.001ppm 이늘었다. 이산화황 (0.008ppm) 의경우 10 년전보다는대폭개선됐지만, 여전히전국 ( 평균 0.005ppm) 에서농도가가장높을뿐아니라전국에서유일하게온산읍화산리측정소에서 1 시간환경기준을초과하기도했다 년부터환경기준 (5.0 μg / m3 ) 이적용되기시작한벤젠은공단지역인울산의 1 개측정소 ( 여천동, 5.7 μg / m3 ) 에서환경기준을초과한것으로조사됐다. 정재환기자 hani@ c 울산신문 ( 무단전재및재배포금지

12 울산시 ] 울산시, 5 월 1 일부터오존경보제실시 2011 년 04 월 27 일 ( 수 ) 09:28:50 워터저널 webmaster@waterjournal.co.kr 울산시는대기중오존 (O3) 의피해를최소화하고오존농도저감을위한시민들의자발적인참여를유도하기위해오는 5 월 1 일부터 9 월 30 일까지 오존경보제 를실시한다고밝혔다. 오존경보는주의보 0.12ppm/h 이상, 경보 0.3ppm/h 이상, 중대경보 0.5ppm/h 이상이면각각발령된다. 오존환경기준은 1 시간 0.1ppm 이하, 8 시간 0.06 ppm 이하이다 오존경보발령은중구, 남구, 동구, 북구, 울주군온산읍, 울주군청량면등 6 개권역으로구분발령된다. 울산시는오존경보가발령되면정부기관, 언론기관, 구 군권역 (480 개소 ) 등총 517 개소에통보한다. 또한휴대폰문자메시지서비스 (UMS) 가입시민들 ( 현재 9 천 662 명가입 ) 에게도발령상황을즉시전파한다. 오존경보발령시단계별조치사항을보면 주의보 발령시에는주민의실외활동및자동차사용을자제해야한다. 경보 발령시에는주민의실외활동제한요청, 자동차사용의제한명령, 사업장의연료사용량의감축권고등이, 중대경보 발령시에는주민의실외활동금지요청, 자동차의통행금지및사업장의조업시간단축명령등이내려진다. 울산시관계자는 여름철오존저감을위해서는가능한승용차사용을자제하고대중교통을이용하는것이바람직하다 고강조하고 오존경보가발령되면특히호흡기질환자, 노약자, 유아등은외출을삼가야한다. 고밝혔다. 한편울산지역에는지난해총 9 회 (7 일 ) 오존경보제가발령됐다. 지역별로는남구 6 회, 동구 1 회, 북구 1 회, 울주 ( 청량 ) 1 회등이다. < 권다인기자 >

17 울산지역냉각탑에서배출되는 HOCl ( 차염소산 ) 예상총량 RR ( 순환수량 ) amount of emission flash-off ton/hr kg/day ton/year Remark 2,000,000 10% 2,000,000 15% 2,000,000 20% 3,000,000 10% 3,000,000 15% , , ,000,000 20% 1, NaOCl 12% as Cl 2 1 ppm/rr

18 Atmosphere Chemistry of the Troposphere (I) In the absence of VOCs yield a steady state ozone concentration Reaction acts as an ozone sink M: any third body like N 2 The amount of ozone produced is strongly dependent on the ultraviolet sunlight intensity, the concentration of VOCs and NOx in the lower atmosphere, temperature, humidity, and cloud cover.

19 Atmospheric Chemistry of the Troposphere (II) In the presence of VOCs higher ozone concentration results because of both an increase in O 3 source (NO 2 ) & a reduction in the O 3 sink (NO) 1) The formation (2.1.5) and reduction (2.1.6) reaction of the peroxyradical ROO* 2) These step allow ozone to accumulate by reducing the ozone sink (NO) and increasing ozone sources (NO 2 )

20 Sources & function of Ozone (O 3 ) 1) NO 2 + hv ( λ<420 nm) NO + O( 3 P) : O 3 adsorbs light in the region from 290 to 320 nm followed by O( 3 M P) + O 2 O 3 M: any third molecule that stabilizes the exited intermediate before dissociates back into reactants eg N 2 2) Ozone is a source of the hydroxyl radical (OH) :reacts rapidly with most air pollutants and trace species found in the atmosphere Although some NO 2 is emitted directly into the atmosphere by combustion process, most is formed by oxidation of NO (the major nitrogenous byproduct of combustion) after dilution in air

21 Sources of OH (1) 1) Photolysis of O 3 : major source O 3 + hv ( λ<320 nm) O 2 + O( 1 D) : formation of exited atoms O( 1 D) + H 2 O 2OH : formation of hydroxyl radical M O( 1 D) O( 3 P) : deactivation to ground state 2) Photolysis of nitrous acid: significant source in polluted atmosphere HONO + hv ( λ<400 nm) OH + NO Source & ambient concentration of HONO are not well known

22 Sources of OH (2) 3) Heterogeneous sources of HONO surface 2NO 2 + H 2 O HONO + HNO 3 HO 2 + NO OH + NO 2 4) Photolysis of organic compounds like formaldehyde HCHO + hv ( λ<370 nm) H + HCO H 2 + CO M H + O 2 HO 2 HCO + O 2 HO 2 +CO The O3-alkene reaction is also source of OH

23 Conversion of NO to NO 2 1) Fig. 2 illustrates chemistry, using ethane as the simplest example 2) Alkyl peroxy (RO 2 ) and hydroperoxy (HO 2 ) free radicals are generated (step 3 and 5) which oxidize NO to NO 2 3) A substantial fraction of the time, the OH is regenerated to continue the reaction Parts of the oxidation of organic compounds, initiated by reactive species such as the OH radical

24 Potential reaction of NO 2 1) 1) Photolysis to form ground-state oxygen atoms O( 3 P) which generate O 3, as well as reaction with OH to form nitric acid 2) 3) 2) When there are sufficient concentrations of both NO 2 & O 3, the nitrate radical (NO 3 ) and dinitrogen pentoxide (N 2 O 5 ) are formed 3) Like OH, NO 3 reacts with organics to initiate their oxidation. NO 3 chemistry is important only at night because it photolyzes rapidly during the day

25 UV

CHAPTER 1. MEASURES OF ATMOSPHERIC COMPOSITION

1 CHAPTER 1. MEASURES OF ATMOSPHERIC COMPOSITION The objective of atmospheric chemistry is to understand the factors that control the concentrations of chemical species in the atmosphere. In this book