Evaluation of a passive sampling method for long ... - ACS Publications

Aug 17, 2018 - EPA Method 325 was developed for continuous passive monitoring of volatile organic compounds (VOCs), particularly benzene, at petroleum...
0 downloads 0 Views 438KB Size
Subscriber access provided by Kaohsiung Medical University

Environmental Measurements Methods

Evaluation of a passive sampling method for long-term continuous monitoring of volatile organic compounds in urban environments Robert Healy, Julie Bennett, Jonathan M Wang, Nicholas S Karellas, Colman Wong, Aaron Todd, Uwayemi Sofowote, Yushan Su, Linda Di Federico, Anthony Munoz, Jean-Pierre Charland, Dennis Herod, May Siu, and Luc White Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.8b02792 • Publication Date (Web): 17 Aug 2018 Downloaded from http://pubs.acs.org on August 18, 2018

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 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 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.

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 33

Environmental Science & Technology

Evaluation of a passive sampling method for long-term continuous monitoring of volatile organic compounds in urban environments Robert M. Healy*1, Julie Bennett1, Jonathan M. Wang1, Nicholas S. Karellas1, Colman Wong1, Aaron Todd1, Uwayemi Sofowote1, Yushan Su1, Linda Di Federico1, Anthony Munoz1, JeanPierre Charland2, Dennis Herod2, May Siu2, Luc White2 1

Environmental Monitoring and Reporting Branch, Ontario Ministry of the Environment,

Conservation and Parks, Toronto, Ontario M9P 3V6, Canada 2

Air Quality Research Division, Environment and Climate Change Canada, Ottawa, Ontario

K4M 1B4, Canada

Corresponding author contact details: [email protected] Ontario Ministry of the Environment, Conservation and Parks 125 Resources Road, Etobicoke, ON M9P 3V6, Canada

ACS Paragon Plus Environment

Environmental Science & Technology

1

Abstract

2

EPA Method 325 was developed for continuous passive monitoring of volatile organic

3

compounds (VOCs), particularly benzene, at petroleum refinery fencelines. In this work, a

4

modified version of the method was evaluated at an Ontario near-road research station in winter

5

to assess its suitability for urban air quality monitoring. Samples were collected at 24 hour and

6

14 day resolution to investigate accuracy for different exposure times. Tubes were analyzed by

7

thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS), and eleven VOCs

8

were quantified including aromatic air toxics. The same VOCs were simultaneously monitored

9

using traditional canister sampling for comparison, and a subset of four were also monitored

10

using a novel miniature gas chromatograph. Good agreement (within 10%) was observed

11

between the 14 day passive tube samples and the canister samples for benzene. However, field-

12

calibrated uptake rates were required to correct passive tube concentrations for lower volatility

13

aromatics. Passive tube deployment and analysis is inexpensive, sampling does not require

14

power and accurate measurements of benzene are demonstrated here for an urban environment.

15

The method is expected to be advantageous for the generation of long term continuous benzene

16

datasets suitable for epidemiological research with greater spatial coverage than is currently

17

available using traditional monitoring techniques.

18 19 20 21 22

ACS Paragon Plus Environment

Page 2 of 33

Page 3 of 33

Environmental Science & Technology

23

Introduction

24

The measurement of volatile organic compounds (VOCs) in ambient air through passive

25

sampling is becoming more prevalent1-4, and applications include indoor air quality5-7, outdoor

26

air quality8-12, and soil vapor intrusion assessments13. Passive sampling approaches include

27

permeation devices14, 15, polyurethane foam disks16, 17, solid phase microextraction fibres18-20 and

28

thermal desorption (TD) tubes packed with sorbent materials21-23. EPA Method 325, involving

29

passive sampling of VOCs on low cost stainless steel TD tubes containing Carbopack X, is

30

currently in use for assessing VOC concentrations at petroleum refineries in the United States

31

under the Code of Federal Regulations (CFR), title 4024. The method has also recently been

32

introduced by refineries in Ontario, Canada, to meet the province’s Petroleum Refining Industry

33

Standard25. Method 325 was developed to enable continuous monitoring of VOCs associated

34

with fugitive emissions from refineries with an emphasis on benzene, a known carcinogen26, 27.

35

Fugitive VOC emissions are difficult to predict through modeling28, and thus continuous year-

36

round VOC monitoring offers the advantage of capturing any unexpected or intermittent

37

emission events, irrespective of their duration.

38

In Method 325 applications, each TD tube is housed in a shelter, fitted with a diffusion endcap,

39

and exposed to ambient air for a period of up to two weeks during which ambient VOCs diffuse

40

to the sorbent and are retained24. While laboratory-based testing has demonstrated good

41

agreement between Method 325 and traditional evacuated canister sampling for a range of VOCs

42

under controlled conditions29, field studies assessing accuracy and potential biases of the method

43

are few, and are focused on petrochemical facility fenceline sampling locations22,

44

previous side-by-side comparison of 24 hour passive Carbopack X tube samples and evacuated

45

canister samples in indoor environments demonstrated good agreement between the two

ACS Paragon Plus Environment

23, 30, 31

. A

Environmental Science & Technology

46

approaches in the range 0.1-28 ppbv, although some low concentration tube samples (