Probing the environmental fate of emerging contaminants and their ecological impacts on aquatic

167 Pages·2017·4.91 MB·English

by  Ziye Sang

Hong Kong Baptist University
HKBU Institutional Repository
Open Access Theses and Dissertations Electronic Theses and Dissertations
6-23-2016
Probing the environmental fate of emerging contaminants and their ecological impacts on
aquatic environment
Ziye Sang
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HONG KONG BAPTIST UNIVERSITY
Doctor of Philosophy
THESIS ACCEPTANCE

DATE: June 23, 2016

STUDENT'S NAME: SANG Ziye

THESIS TITLE: Probing the Environmental Fate of Emerging Contaminants and Their Ecological
Impacts on Aquatic Environment

This is to certify that the above student's thesis has been examined by the following panel
members and has received full approval for acceptance in partial fulfillment of the requirements for the
degree of Doctor of Philosophy.

Chairman: Prof. SO Shu Kong
Professor, Department of Physics, HKBU
(Designated by Dean of Faculty of Science)

Internal Members: Dr. KWONG Daniel W J
Associate Professor, Department of Chemistry, HKBU
(Designated by Head of Department of Chemistry)

Dr. REN Kangning
Assistant Professor, Department of Chemistry, HKBU

External Members: Prof. LAM Hon Wah
Professor and Assistant Dean
Department of Biology and Chemistry
City University of Hong Kong

Prof. LIN Angela Yu-Chen
Professor
Graduate Institute of Environmental Engineering
National Taiwan University
Taiwan

Proxy: Dr. SHIU Kwok Keung
Associate Professor, Department of Chemistry, HKBU
(as proxy for Prof. LIN Angela Yu-Chen)

In-attendance: Dr. LEUNG Kelvin S Y
Associate Professor, Department of Chemistry, HKBU

Issued by Graduate School, HKBU
Probing the Environmental Fate of Emerging
Contaminants and Their Ecological Impacts on
Aquatic Environment

SANG Ziye

A thesis submitted in partial fulfillment of the requirements
for the degree of
Doctor of Philosophy

Principal Supervisor: Dr. LEUNG Kelvin S Y

Hong Kong Baptist University
June 2016
Declaration
I hereby declare that this thesis represents my own work which has been done
after registration for the degree of PhD at Hong Kong Baptist University, and has
not been previously included in a thesis or dissertation submitted to this or any
other institution for a degree, diploma or other qualifications.

Signature: ______________________
Date: June 2016

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Abstract
In recent years, new classes of aquatic pollutants have received growing concerns
from the environmentalists due to their unclear effects and increasing release into
the water environment. Generally, before entering the aquatic ecosystem, many of
these emerging contaminants are deemed safe active ingredients in the
commercial products. This may lead to the underestimation of their potential
impacts to the environment, once these substances were drained into the natural
waters. So far, a wide range of emerging contaminants are still not well studied.
In this thesis work, the environmental behaviors for two typical groups of
emerging contaminants, which are frequently used in personal care products, are
systematically probed in the aquatic ecosystem. One is the hydrophilic
compounds – artificial sweeteners and the other one is the moderate hydrophobic
compounds – ultraviolet (UV) filters.
Acesulfame and sucralose are two of the most commonly used artificial
sweeteners, which are a newly recognized class of emerging contaminants due to
their widespread occurrence and extreme persistence in water environment. To
date, however, their environmental behaviors, fates as well as long term
ecotoxicological contributions in our water resources still remain largely
unknown. In this work, a photodegradation investigation with UV/TiO was
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performed on these two artificial sweeteners, which projected their potential
impacts under prolonged exposure to intensive solar irradiation. Real-time
observation of the degradation profiles in both sweeteners illustrated that
formation of new photo by-products under prolonged UV irradiation is highly
viable. For the first time, acute toxicity for the degradates of these two sweeteners
were measured and the enhancement in their ecotoxicity has been observed
during the irradiation. In an attempt to neutralize this prolonged environmental
threat, the feasibility of UV/TiO as an effective mineralization process in
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wastewater treatment was evaluated for both sweeteners. As a result, relatively
higher removal efficiencies for acesulfame and sucralose were achieved in this
study.
For UV filters, a comprehensive investigation on their environmental behaviors
and impacts was described in this thesis, covering the occurrence study in surface
water and biota, environmental fate and their ecological risks. In the first step, an
analytical method based on ultra performance liquid chromatography-tandem
mass spectrometry (UPLC-MS/MS) was developed for the simultaneous
determination of twelve UV filters in the environmental waters, which achieved
good sensitivity to sub-ng/L levels. To monitoring their occurrence in local
marine environment, the regional distribution of these sunscreen compounds was
monitored along the coastline of Hong Kong. At the same time, considering the
intensive consumption of sunscreen products in hot weathers, seasonal variation
of UV filters between summer and winter was taken into consideration in our
occurrence study. Additionally, we also monitored their occurrence in the
drinking water supply system of Hong Kong, including the source water in
Dongjiang, raw water in local reservoirs and tap water collected from urban
communities, to support a good management on the reliable water supply.
Furthermore, the distribution results indicated that the incomplete removal of UV
filters in the effluents could be a major source for their release into the
environmental waters. Aiming to achieve the complete removal of such
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compounds, a powerful technique of ozonation was employed in this study and
the preliminary operational conditions were further provided. Secondly, in order
to gain a better understanding of their environmental fate in surface water, a
simulative catalytic photodegradation study with UV/TiO were performed to
2
investigate the photostability, phototoxicity and the transformation pathways of
seven selected UV filters. During the photodegradation, several transformation
products were primarily identified. Thirdly, since lipophilic sunscreens were
easily accumulated in the biota, we also made efforts to monitor their occurrence
in marine organisms of different species, including farmed fish, wild mussels,
prawns and sea urchin, which were collected from local offshore areas. Last but
not the least, according to the measured concentrations of UV filters in Hong
Kong marine environment, we further performed the ecological risk assessment
with the approach specific to the marine aquatic compartment, so as to provide
the overall understanding on the environmental impacts of these UV filters.

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Acknowledgement
Towards the end of this these thesis work, I would like to express my gratitude to
all those have provided generous support throughout the entire postgraduate
study.
My deepest gratitude goes first and foremost to my supervisor, Dr. Kelvin
Sze-Yin Leung, for his insightful guidance and immense patience. His
encouragement and unwavering support has sustained me through frustration and
depression. Without his consistent and illuminating instructions, this thesis could
not reach its present form. My years and experience in Dr. Leung’s group will be
the valuable wealth for the rest of my life.
My heartfelt appreciations go to my past and present group fellows Dr. Y.-K.
Tsoi, Ms. Sabrina Y.-N. Jiang, and Ms. Judy T.-S. Lum, who shared the
bitter-sweetness during the progress of my study. Special thanks are due to Ms.
Rosi F. Tohidi and Dr. X.-Q. Yi for their valuable experience and selfless sharing
which have eased me through a confused junior year.
Also, I would like to thank Dr. Patrick Y.-K. Yue from the Department of
Biology and Dr. P.-K. So from the Hong Kong Polytechnic University, for the
instrumentation support and technique training.
I owe my sincere gratitude to all technical and supporting staffs in the department
and Chemical Testing Services, especially Mr. Bohr K.-B. Cheung, Mr. Tom Fu
and Ms. Cathy Li as well as Mr. Issac C.-C. Cheng, Ms. April K.-Y. Lau and Mr.
Eric W.-H. Jim, for their helpful comments and necessary assistance.
The receipt of postgraduate studentship (2012-2015) from the University Grants
Council is gratefully acknowledged.
Last but not least, I have to express my gratefulness to the great love and care
from my family, who always support my every decision and encourage me to
walk through the toughest moments in these years.

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Table of Contents
Declaration ............................................................................................................. i
Abstract ................................................................................................................. ii
Acknowledgement................................................................................................ iv
Table of Contents .................................................................................................. v
List of Tables ........................................................................................................ ix
List of Figures ....................................................................................................... x
List of Abbreviations and Symbols .................................................................... xi
Chapter 1 Introduction ........................................................................................ 1
1.1 Emerging contaminants ............................................................................. 1
1.2 Current status of studies in aquatic environment ...................................... 3
1.3 Target compounds in this thesis work ....................................................... 7
1.3.1 Artificial sweeteners ........................................................................ 7
1.3.2 UV filters ......................................................................................... 8
1.4 Objectives of this thesis work.................................................................... 9
1.5 References ............................................................................................... 10
Chapter 2 Photodegradation and Ecotoxicity Study of Artificial Sweeteners
.............................................................................................................................. 17
2.1 Introduction ............................................................................................. 17
2.2 Experimental............................................................................................ 19
2.2.1 Chemicals and reagents ................................................................. 19
2.2.2 Photodegradation profiling ............................................................ 19
2.2.3 Instrumental analysis ..................................................................... 19
2.2.4 Bioluminescent Microtox test ........................................................ 20
2.2.5 Removal treatment......................................................................... 21
2.3 Results and discussions ........................................................................... 22
2.3.1 Degradation toxicity ...................................................................... 22
2.3.1.1 Sucralose.............................................................................. 24
2.3.1.2 Acesulfame .......................................................................... 26
v
2.3.2 Removal treatment......................................................................... 29
2.4 Chapter summary..................................................................................... 34
2.5 References ............................................................................................... 35
Chapter 3 A Comprehensive Occurrence Investigation of UV Filters in Local
Aquatic Environment and Their Removal Treatment Study ......................... 40
3.1 Introduction ............................................................................................. 40
3.2 Experimental............................................................................................ 44
3.2.1 Chemicals and reagents ................................................................. 44
3.2.2 Sample locations and collection .................................................... 44
3.2.2.1 Seasonal collection of seawater ........................................... 44
3.2.2.2 Drinking water supply system of Hong Kong ..................... 46
3.2.3 Analytical method .......................................................................... 48
3.2.4 Bench-scale ozonation experiments .............................................. 49
3.2.5 Instrumental analysis ..................................................................... 50
3.3 Results and discussions ........................................................................... 52
3.3.1 Method validation .......................................................................... 52
3.3.2 Environmental occurrence of UV filters in surface seawater ........ 53
3.3.2.1 Occurrence in Hong Kong seawater .................................... 53
3.3.2.2 Seasonal pattern ................................................................... 57
3.3.2.3 Spatial distribution in Hong Kong ....................................... 59
3.3.3 Occurrence of UV filters in drinking water supply system ........... 63
3.3.4 Removal treatment of ozonation ................................................... 65
3.4 Chapter summary..................................................................................... 69
3.5 References ............................................................................................... 71
Chapter 4 Photodegradation and Ecotoxicity Study of UV Filters................ 77
4.1 Introduction ............................................................................................. 77
4.2 Experimental............................................................................................ 80
4.2.1 Chemicals and reagents ................................................................. 80
4.2.2 Photodegradation ........................................................................... 81
4.2.3 Instrumental analysis ..................................................................... 82
4.2.4 Bioluminescent Microtox test ........................................................ 83
4.3 Results and discussions ........................................................................... 85
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4.3.1 Ethyl p-amino benzoic acid (Et-PABA) ........................................ 85
4.3.1.1 Catalytic photodegradation profiles .................................... 85
4.3.1.2 Identification of photodegradation products and their
transformation profiles .................................................................... 88
4.3.1.3 Phototoxicity evaluation ...................................................... 92
4.3.2 3-Benzylidene camphor (3-BC) .................................................... 94
4.3.2.1 Catalytic photodegradation profile ...................................... 94
4.3.2.2 Identification of photodegradation products and their
transformation profiles .................................................................... 96
4.3.3 Benzophenone group ................................................................... 101
4.3.3.1 Catalytic photodegradation profiles .................................. 101
4.3.3.2 Phototoxicity evaluation .................................................... 105
4.3.3.3 Degradation products of BP-type UV filters ..................... 106
4.4 Chapter summary................................................................................... 108
4.5 References ............................................................................................. 110
Chapter 5 Occurrence Study of UV filters in Marine Organisms and Their
Ecological Risk Assessment in Hong Kong Marine Environment ............... 115
5.1 Introduction ........................................................................................... 115
5.2 Experimental.......................................................................................... 117
5.2.1 Chemicals and reagents ............................................................... 117
5.2.2 Sample collection and preparation .............................................. 117
5.2.3 Analytical procedures .................................................................. 119
5.2.4 Instrumental analysis ................................................................... 120
5.2.5 Analytical method validation ....................................................... 121
5.3 Results and discussions ......................................................................... 122
5.3.1 Method validation results ............................................................ 122
5.3.1.1 Validation results ............................................................... 122
5.3.1.2 Matrix effect study ............................................................ 124
5.3.2 Environmental occurrence of UV filters in marine organisms .... 125
5.3.2.1 Concentrations in marine organisms ................................. 125
5.3.2.2 Spatial distribution in Hong Kong ..................................... 130
5.3.2.3 Global comparison............................................................. 133
5.3.3 Ecological risk assessment .......................................................... 135
5.4 Chapter summary................................................................................... 140
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