Aspects of toxicology of estuarine sediments: The Port of Durban as a case study

摘要

In some instances chemical tests performed on sediments indicate high probabilities of harmfulrneffects according to a wide range of internationally recognised sediment quality guidelines. ThernPort of Durban, with its close proximity to industrial, urban and agricultural activities receives arnnumber of chemical pollutants that precipitate from the water column and accumulate in itsrnsediments. Chemical analysis of these sediments has indicated elevated levels of chemicals that,rnaccording to the sediment quality guidelines, might cause adverse biological effects. However,rnalthough chemical concentrations are elevated, this does not necessarily indicate that they arernpresent in bioavailable concentrations or that they are harmful to those organisms that come intorncontact with them. Thus, chemical tests alone do not provide an accurate indication of adversernbiological effects.rnIn this regard, bioassay testing procedures have been developed using representative conditionsrnand organisms to help understand the bioavailability and toxicity of chemicals adsorbed ontornsediments. Further, concurrent procedures have been developed such as toxicity identificationrnand evaluation (TIE) that allow the identification and characterisation of chemicals that causerntoxicity in sediments. In this dissertation, replicate samples were taken from a contaminatedrnsite in the Port of Durban which past analyses have indicated to contain sediments that havernpore waters that are toxic. Sediment sample replicates taken in the vicinity of the Sharks Boardrnlaunch site, were shown to contain pore waters that inhibited fertilisation of eggs from the SearnUrchin Tripnuestes gratilla. TIE procedures where then conducted on these sediment pore watersrnto determine the probable chemical classes that could have been responsible for the toxicrnresponse. Preliminary evidence from pore water TIE procedures indicates that this technique mayrnbe useful in future to better understand the causes of toxicity in sediments.