Evaluation On The Persistent Toxic Substances Contents In Chinese White Dolphins (Sousa Chinensis) And Their Habitat At The Marine Area Of Dajin Island

Water area of Dajin Island is one of habitats of Chinese white dolphins (Sousachinensis). Utilizing the two dead Chinese white dolphins which were found in themarine area of Dajin Island, the concentrations and distribution of Persistent ToxicSubstances in Chinese white dolphins and their habitat were investigated in thisstudy. Environmental quality of the habitat was also evaluated in order to provide thescientific gist for protection of Chinese white dolphins.April 2006, two dead Chinese white dolphins were found in the waters of DajinIsland, which included one male and one female. Their morphologic characters weremeasured and compared detailedly, and they were consistent with the commoncharacters of its species. Anatomized their stomaches,one was empty,and the reasonof its death was not known;but another one was stuffed by a gill net, which indicatedthat the shore fishery threatened the Chinese white dolphin's living on a certainextent.Concentrations and distributions of nine kinds of heavy metals in Chinese whitedolphins were analyzed by microwave digesting, atomic absorptionspectrophotometer and double path atomic fluorescence spectrophotometer. Theresults showed that the trend of heavy metals in Chinese white dolphin is Fe＞Zn＞Cu＞Mn＞Ni＞As＞Cr＞Cd＞Pb.The liver and kidney of Chinese whitedolphin is the main accumulated organ for heavy metals, and the blubber has the leastburthen. Compared with Xiamen, Beibu Gulf and Hongkong's, the mean contents ofheavy metals in Chinese white dolphins at the waters of Dajin Island is lower thanBeibu Gulf and Hongkong, and has obvious differences on different heavy metals.The content characteristic of heavy metals in Chinese white dolphins is consistent atthe four marine areas.Concentrations of heavy metals in sea water,sediments and organisms(Fish,Crustacea and Cephalopoda) at the habitat were analyzed. The results showed,the sea organisms have obvious enrichment to the heavy metals in coastal waters, the high concentrations of heavy metals in the liver of Chinese white dolphins isaccumulated grade by grade in food chain. The environment quality of the habitat isevaluated. It is indicated that the water quality in this habitat is between the first andthe second rank, sediment quality is the first rank, and the heavy metals in three kindsof organisms are all lower than the standard. It also indicated that the marinearea hasn't been polluted by heavy metals. The environmental quality in this waterarea is fit to Chinese white dolphins' living. Heavy metals level at the marine area ofDajin Island is in the low value section of the Pearl River estuarine zoon, it maybe an important reason of Chinese white dolphins selecting this area as theirhabitat.Concentrations and distributions of organochlorine pollutants-DDT, HCHand PCB in Chinese white dolphins were analyzed by GC-ECD.As the result, inall samples, HCH and PCB were not detected but sixisomeric compoundsof DDT,contents of pp-DDE and pp-DDD were relatively high. Blubber ofChinese white dolphins has great enrichment capabilities to the organochlorinepollutants, and muscle, liver are in the next place. Environmental quality of thehabitat on organochlorines is evaluated. The results indicate that the quality on HCHand PCB is good, and DDT is relatively high, but has no evident menace toChinese white dolphins' living.