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|Title: ||Concentrations of persistent organohalogen compounds in waterbird eggs in south China : method development and risk assessment|
|Other Titles: ||Guan yu Zhongguo nan bu shui niao dan zhong chi jiu xing you ji lu hua wu shui zhun de fang fa yan jiu he feng xian ping jia|
|Authors: ||Wang, Yuan (王媛)|
|Department: ||Department of Biology and Chemistry|
|Degree: ||Doctor of Philosophy|
|Issue Date: ||2008|
|Publisher: ||City University of Hong Kong|
|Subjects: ||Organohalogen compounds -- Environmental aspects -- China.|
Persistent pollutants -- Environmental aspects -- China.
Water birds -- Eggs -- Contamination -- China.
|Notes: ||CityU Call Number: TD196.H35 W36 2008|
xvi, 209 leaves : ill. 30 cm.
Thesis (Ph.D.)--City University of Hong Kong, 2008.
Includes bibliographical references (leaves 167-209)
|Abstract: ||Hong Kong, located at the mouth of the Pearl River in South China, receives persistent
toxic contaminants into its marine habitats from a variety of sources including shipping
activity, wastewater, industrial wastes and agricultural runoff. The rapid development of
industrial and urban areas in the hinterland of the Pearl River Delta is also an
increasingly important source of contaminants to Hong Kong, especially via riverine and
International negotiations to reduce and eliminate the emission and discharges of an
initial set of twelve “persistent organic pollutants” (POPs) were initiated at the
Stockholm Convention on Persistent Organic Pollutants in May 2001. The twelve
substances that were addressed at the Stockholm Convention were: aldrin, endrin,
dieldrin, dichlorodiphenyltrichoroethanes (DDTs), polychlorinated biphenyls (PCBs),
polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs),
chlordane, toxaphene, heptachlor, hexachlorobenzene (HCB) and mirex. However, the
data regarding these compounds are incomplete or missing. It is important to have the
basic or background information on these compounds in order to evaluate the policies
carried out to reduce and eliminate the emission or discharge of these chemicals.
Polybrominated diphenyl ethers (PBDEs) and perfluorinated compounds (PFCs) are
emerging compounds of concern. PBDEs are bioaccumulative and toxic in many
toxicological animal tests, while perfluorooctane sulphonate (PFOS), one of the well-known PFCs of concern, is also suggested to be carcinogenic. It is also important to
evaluate the occurrence and the degree of contamination in Hong Kong.
Water birds are valuable and useful for environmental monitoring. They are particularly
susceptible to environmental contaminants because they are long-lived and occupy the
top trophic level of many food webs. Consequently, they are able to integrate pollutant
levels over a broad area by bioaccumulation. Contaminant levels in water bird eggs,
therefore, provide important and useful information for monitoring changes in
The contamination status of the marine environment in Hong Kong was studied by the
measurement of concentrations of these pollutants in the eggs of selected water bird
species: Little Egret (Egretta garzetta), Chinese Pond Heron (Ardeola bacchus), Great
Egret (Ardea alba), and Black-crowned Night Heron (Nycticorax nycticorax). The
greatest mean concentrations of total polychlorinated biphenyls (PCBs) (4310 ng/g lipid
wt.), total toxaphenes (295 ng/g lipid wt.), endrin (31.3 ng/g lipid wt.) and total
chlordanes (975 ng/g lipid wt.) were detected in the eggs from Mai Po Village and were
significantly greater than Night Heron eggs from A Chau. These results suggested
spatial variation in the levels of contamination between the eastern and western waters
of Hong Kong. Night Heron eggs from A Chau contained the lowest concentrations of
most of the contaminants except for HCB (241 ng/g lipid wt.). Inter-species variation in
feeding habitats, foraging distance and metabolism rate of birds likely resulted in the
inter-specific variation in the contaminant concentrations in eggs of Night Heron and Great Egret from A Chau. The great proportion of p,p’-DDE and o,p’-DDE in the egg
samples indicated that DDTs in the environment are probably from historical inputs.
The risk characterization demonstrated the potential risks to birds associated with
exposure to DDE, which was found to cause a reduction in survival of young in Hong
The greatest mean total PCDD/F concentration was found in Night Heron eggs from A
Chau (PCDDs: 1020pg/g lipid wt. and PCDFs: 165pg/g lipid wt.), whereas lower
concentrations were detected in egg samples of Little Egret and Chinese Pond Heron
from Mai Po Village (PCDDs: 520pg/g lipid wt. and PCDFs: 167pg/g lipid wt.), and the
least concentrations were found in egg samples of Chinese Pond Heron from Ho
Sheung Heung (PCDD: 484pg/g lipid wt. and PCDF: 80.1pg/g lipid wt.). Eggs of
Chinese Pond Heron and Little Egret from Mai Po Village had the greatest coplanar
PCB concentrations, which were approximately two-to-three times greater than those of
Chinese Pond Heron from Ho Sheung Heung and Night Heron from A Chau.
Concentrations of PBDEs in Great Egret eggs in the present study were similar to those
in Little Egret from Mai Po and Night Heron from A Chau. The absence of
inter-specific and/or inter-site variations of PCDD/DFs, coplanar PCBs and PBDEs
suggested the similar exposure levels of these contaminants to birds in northeastern and
northwestern of Hong Kong. This finding further indicated the lesser importance of
point source pollution over non-point source pollution because these contaminants
come from a wide variety of human or industrial activities (e.g. incineration,
combustion processes, and sewage treatment plants, as well as through chemical manufacturing processes of products containing related compounds), not from a single
discharge point. The overall outcome of the risk characterization demonstrated that
there are potential risks to birds associated with exposure to PCDD/Fs and BDE 99.
Abnormalities in hatchlings and growth depression due to PCDD/Fs, and oxidative
stress due to BDE 99 in eggs may be a potential cause for concern.
Total concentrations of the 11 PFCs in waterbird eggs ranged from 27.0 ng/g ww in a
Great Egret egg from Hong Kong to 160 ng/g ww in a Night Heron egg from
Quanzhou. Significant differences in PFOS concentrations were found among species,
but not among locations. The composition profiles of the individual PFCs among egg
samples were generally similar. Preliminary risk assessment suggests that there is no
immediate risk of a reduction in offspring survival in water birds in South China due to
PFOS, but more information is needed on the potential effects of PFCs in water birds.
Apart from studies on chemical analysis and risk evaluation of these chemicals to water
birds in South China, an enzymatic digestion with solid phase extraction cleanup
method on PFCs on biological tissues was developed to compensate for the limitations
of the existing conventional extraction method (an ion pairing method) on biological
|Online Catalog Link: ||http://lib.cityu.edu.hk/record=b2339787|
|Appears in Collections:||BCH - Doctor of Philosophy |
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