Abstract: Dumping dredged sediment into the ocean has become controversial due to its potential environmental implications and threats to human health. Dredged sediment often contains various contaminants which significantly impact marine ecosystems. This presentation highlights the need for more stringent regulations and innovative sediment management strategies to mitigate these impacts by citing two case studies the author involved: (1) Mass fish-kill at fish culture zones due to dumping dredged sediment without safeguarding the environment, and (2) Stringent environmental regulations were enforced for dumping sediment at the ocean. Before the construction of the contained aquatic disposal (CAD) facility to the South of The Brothers Contaminated Mud Pits (SB CMPs) (near the Hong Kong Airport), the Civil Engineering and Development Department (CEDD) conducted a detailed review and update of EIA findings for the facility in 2009/2010. An Environmental Monitoring and Audit (EM&A) program was subsequently implemented, covering the dredging, disposal, and capping operations of the CMPs. Stringent procedures were followed concerning the construction of disposal pits, disposal of contaminated mud, capping pits, and an extensive environmental monitoring program. The EM&A procedures (from July 2013 to June 2017) included the baseline surveys, monitoring of water and sediment quality, bioassays of sediment toxicity, recolonization of benthic organisms, and loading of major contaminants: heavy metals (Cr, Cd, Cu, Hg, Ni, Zn, Pb, Ag), metalloid (As), organic pollutants (PAH, DDT, PCB, TBT), and total organic carbon. The overall results indicated no drastic water and sediment quality changes due to the operations. The potential impacts were monitored on the Ma Wan mariculture site (the most sensitive receiver) and other mariculture sites. The EM&A data obtained under the Project for these four years were compared against the corresponding key Water Quality Objectives. No unusual changes in water quality (especially DO and E. coli), which may threaten fish health, were noted. Based on the results, it can be concluded that there is no need to conduct additional monitoring/mitigation measures or studies to examine the Project’s impact on mariculture zones.

Biography: Professor Wong is a Member of the European Academy of Sciences and Arts, and Chang Jiang Chair Professor of the Ministry of Education, China. He served as the Editor-in-Chief of ‘Environmental Geochemistry and Health’ (Springer Nature) for 20 years (2002-2023). Professor Wong was the Coordinator of Central and North-East Asia of ‘Regionally Based Assessment of Persistent Toxic Substances’ and a Panel Member (of 3 experts) of ‘Chemicals Management Issues of Developing Countries and Countries with Economies in Transition’, sponsored by UNEP/GEF, during 2001-2003 and 2010-2012, respectively. His research areas included ‘Environmental toxicology’; ‘Ecological restoration’; and ‘Resource reuse’. He has published over 840 SCI papers. In addition to his PhD (Durham), he was awarded two higher Doctoral Degrees: DSc (Durham) and DSc (Strathclyde) based on published papers in 1992 and 2004. Professor Wong is ranked 6th for 3 years and 8th for 1 year (career-long ranking) and is listed as the top Chinese scientist in Environmental Science according to the World’s Top 2% Scientists (Stanford University, 2020-2023). According to Research.com's Best Researchers in Various Disciplines (2nd Ed, 2023), he ranked No. 1 in China under Environmental Science.