Kenneth Mei Yee Leung
The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Hong Kong, China
The determination of PNECs and sediment quality guidelines (SQGs) of toxic chemicals in marine sediment is very crucial in ecological risk assessment, sediment quality management (e.g. mud disposal in the sea) and environmental remediation (e.g. dredging of contaminated mud). However, current methods of deriving sediment PNECs are primarily based on toxicity data generated from laboratory ecotoxicity bioassays that often lack ecological realism. To tackle this issue, we have developed 2 novel alternative approaches to scientifically derive site-specific SQGs by utilising field data of benthic biodiversity and contaminant concentration which are concurrently measured in sediment samples collected from the area of concern.
In this talk, I first described the principle of these field-based approaches. Secondly, I introduced the field-based species sensitivity distributions (f-SSDs) approach, which is based on the relationship between species abundance and contaminant level (Leung et al, 2005; Kwok et al, 2009). Since its establishment, f-SSDs have been utilised in different parts of the world such as Europe, Hong Kong, New Zealand and the United States. The Norwegian continental shelf and the marine environment of Hong Kong were taken as examples to illustrate the methodology. Thirdly, I presented the community sensitivity distributions (CSDs) approach which is founded on the relationship between species density and contaminant level, and makes use of Empirical Bayes methods (Gilbert et al, 2014). Overall, the field-data-derived SQGs appear to be more environmentally relevant and ecologically realistic. The f-SSD and CSD can be directly adopted as ‘effect distributions’ for probabilistic risk assessment. The field-data-derived SQGs can be employed as site-specific guidelines, and used to validate the current PNECs or SQGs derived from laboratory ecotoxicity data. Finally, the limitation of these field-based approaches were discussed, while their recent development and application in different countries were highlighted.