Ecotoxicological Assessment of Persistent Organic and Heavy Metal Contamination in Hong Kong Coastal Sediment

Abstract

The aim of the present project is to determine the feasibility of measuring hepatic cytochrome P4501A1 (CYP1A1) and metallothionein (MT) mRNA in fish as an integrative measurement of persistent organic pollutants (POPs) and heavy metal contamination in sediment arising in Hong Kong. Sediment samples were collected from different sites, including Victoria Harbour (VS6), Yim Tin Tsai (YTT) at Tolo Harbour, Mai Po marshes (MPM) at Deep Bay, and Southern Waters (SS6) of coastal waters. The samples were analyzed for total and extractable concentrations of Cd, Cu, Ni, Zn, and Pb, as well as PCBs and PAHs. In addition, biomarker responses were studied in tilapia exposed experimentally to coastal sediment for 7 days. Using RT-PCR technique, hepatic CYP1A1 and MT mRNA were measured. Three control groups were used, including one negative control group maintained in sea water only; the second and third positive control groups were in sea water but were intraperitoneally injected with either beta-naphthoflavone (40 microg/g body weight) or cadmium chloride (10 microg/g body weight), respectively. The chemical data showed that VS6, YTT, and MPM were classified as Class C sediment according to the sediment quality criteria defined by the Hong Kong Environmental Protection Department, indicating the sites were heavily polluted. The exposure of tilapia to the sediment induced hepatic CYP1A1 (VS6 > YTT > MPM > SS6) and MT (VS6 > MPM > YTT > SS6) levels. The induction patterns were comparable to the levels of POPs and metal contamination in the sediment, indicating that the biomarker responses could be used to differentiate low to high levels of contamination among sediment.

The spatial and temporal distribution of heavy metals in sediments of Victoria Harbour, Hong Kong

“…The sediments in Victoria harbour have been found to be highly contaminated with Cu, Zn, Cr, and Pb due to the discharge of untreated industrial waste and sewage since the 1960s (Yim, 1981;Wong et al, 1995;HKEPD, 2003). Metals in the sediments of the harbour have also been found to induce toxic effects in fish and algal bioassays (Wong et al, 1995;Wong et al, 2000). Over the last two decades, measures aimed at improving the environment, such as the enactment of the Water Pollution Ordinance, the introduction of unleaded petrol, the operation of a chemical waste treatment centre, and the implementation of the Harbour Area Treatment Scheme (HATS) have resulted in a reduction in the amount of metals being discharged into Victoria Harbour (HKEPD, 2000).…”

Killifish metallothionein messenger RNA expression following temperature perturbation and cadmium exposure

“…In addition, field studies demonstrate that MT concentrations in fish and shellfish correlate well with environmental levels of exposure to Cd, Zn, and Cu (Roch et al 1982;Weidow et al 1982;Brouwer 1984, 1987;Roch and McCarter 1984;Brown et al 1987;Hogstrand et al 1991;Hamza-Chaffai et al 2000;Wong et al 2000).…”

Spatio-temporal variation in sediment biochemistry alters larval habitat selection and juvenile performance in the polychaete Capitella sp. I

“…In winter, the Kuroshio Current (high salinity and temperature) affects the hydrography in this region. In addition to these natural events, negative human impacts due to pollution and sewage discharge are serious in the study area (see Wong et al 2000). Therefore, this area was chosen for an investigation of spatio-temporal variation in soft-bottom biochemical characteristics in a heterogeneous marine environment and their consequent influence on larval metamorphosis and juvenile performance under laboratory conditions.…”

“…The westernmost site (PC) is heavily affected by the discharge from the Pearl River and the easternmost site (TLC) is oceanic. The transition sites, VHW, VH, and VHE are polluted by domestic sewage (raw or primarily treated) discharges from some 3.5 million people (Wong et al 2000). Samples were collected on 4 sampling dates: 13 August 2004, 14 December 2004, 17 March 2005and 12 June 2005.…”