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Title: Trace elements and trace organic pollutants in tissues of Indo-Pacific humpback dolphins (Sousa chinensis) and finless porpoises (Neophocaena phocaenoides) from south China waters with particular reference to Hong Kong
Other Titles: Xianggang ji nan Zhongguo shui yu Yindu Taiping Yang tuo bei tun, jiang tun zu zhi nei wei liang yuan su ji you ji wu ran wu de han liang
香港及南中國水域印度太平洋駝背豚, 江豚組織內微量元素及有機污染物的含量
Authors: Leung, Chun Man Clement (梁進文)
Department: Dept. of Biology and Chemistry
Degree: Master of Philosophy
Issue Date: 2007
Publisher: City University of Hong Kong
Subjects: Chinese white dolphin -- South China Sea
Dolphins -- South China Sea
Marine pollution -- South China Sea
Trace elements in water
Notes: CityU Call Number: QL737.C432 L48 2007
Includes bibliographical references (leaves 132-145)
Thesis (M.Phil.)--City University of Hong Kong, 2007
xi, 145 leaves : ill. (some col.) ; 30 cm.
Type: Thesis
Abstract: The coastal environment of southern China, especially the Pearl River Estuary and Hong Kong, receives persistent toxic pollutants into marine habitats from a variety of sources, including shipping activity, wastewater, industrial waste, and agricultural runoff. The long-term, and often indiscriminate, discharge of such contaminants as trace metals, organochlorine pesticides, and polychlorinated biphenyls has compromised water and sediment quality, with potentially detrimental implications for environmental quality and human and wildlife health. In particular, the rapid development of industrial and urban areas in the Pearl River Delta is an increasingly important source of contaminants to Hong Kong and its surrounding areas, especially via riverine and aerial inputs. In Hong Kong waters, 16 species of dolphins, porpoises, and whales have been recorded, although only the Indo-Pacific humpback dolphin (Sousa chinensis) and the finless porpoise (Neophocaena phocaenoides) reside in local waters. Local cetaceans, particularly the Indo-Pacific humpback dolphin, are of great conservation and cultural importance. Many studies have revealed that environmental pollution, over-fishing, habitat loss, anthropogenic activities such as shipping, and infrastructure projects pose the major threats to the cetaceans that inhabit the coastal areas of southern China. The Pearl River Delta is an important habitat for these animals, and the river drains a wide catchment area and is the source of many contaminants. These contaminants may threaten the long-term sustainability of the coastal system and, particularly, the dolphin populations in the northwestern waters and porpoise populations in the southern and eastern waters of Hong Kong. Post-mortem investigations on stranded cetaceans from southern Chinese waters, particularly from Hong Kong, have revealed that these animals had accumulated many contaminants in concentrations that were of concern for their health. This study examined the potential risks of trace elements and trace organic pollutants on the cetaceans living in southern Chinese waters. In the first part of the study, biopsy (skin and blubber) samples were taken from free-ranging humpback dolphins in Hong Kong waters, and tissue samples (skin and blubber) were collected from stranded dolphins from Hong Kong, Zhuhai (a city on the Pearl River Estuary), and Xiamen (a city along the southern Chinese coast). Concentrations of trace organic contaminants (polycyclic aromatic hydrocarbons [PAHs], petroleum hydrocarbons [PHCs], polychlorinated biphenyls [PCBs], and organochlorine pesticides [OCPs]) in the biopsy samples of the live dolphins and tissue samples of the stranded specimens were analyzed by gas chromatography (GC). This study provided data on the tissue concentrations of trace organic pollutants in live dolphins in Hong Kong waters, and the data were compared with those obtained from stranded dolphins from Hong Kong, Zhuhai, and Xiamen. In addition, concentrations of trace organic pollutants (PCBs and OCPs) in the blubber samples of Hong Kong dolphins and porpoises were measured by gas chromatography with an electron capture detector. A sequential dual column system was used to enhance the identification and confirmation of OCPs and PCB congeners in the GC chromatograms. The potential impact of trace organic pollutants on cetaceans was evaluated by a hazard quotient (HQ) analysis under best- and worst-case scenarios. Neither the humpback dolphins nor the finless porpoises showed a critical risk in total PCBs and TEQs (HQ < 1) in the best-case scenario. For another part of the study, trace elements (Cd, Hg, Zn, Cu, Ni, Cr, Pb, Se, As, Mo, Ti, Co, Ag, Sb and Mn) in the tissue (blubber, liver, kidney, and muscle) samples of the stranded cetaceans (Indo-Pacific humpback dolphins [from Hong Kong, Zhuhai, and Xiamen] and finless porpoises [from Hong Kong]) were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The potential impact of the trace elements on cetaceans was evaluated by a hazard quotient (HQ) analysis, under best- and worst-case scenarios. For the humpback dolphins, copper in the Hong Kong samples showed the highest HQ (HQ = 474.63) among all of the trace elements used in the worst-case scenario. Under the best-case scenario, zinc showed the highest HQ in both the humpback dolphins in Zhuhai (HQ = 20.95) and the finless porpoises (HQ = 9.20) in Hong Kong. Overall, the HQs of copper and zinc in the finless porpoises and the humpback dolphins from all three locations were comparatively high (HQ > 5.0 in the best-case scenario). There are evidences of bioaccumulation of certain trace elements and trace organic pollutants in the Hong Kong cetaceans. Furthermore, differences in bioaccumulation patterns of trace elements and trace organics between males and females, and different age groups were also examined. In conclusion, the lack of threshold effect values for many of the chemical contaminants precluded a detailed risk assessment for the cetaceans. Further studies are required to validate the risks of various contaminants, particularly persistent organic pollutants, on the two cetacean species to maintain the well-being and sustainability of these animals in southern Chinese waters.
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