The Characteristics Of Heavy Metal Pollution And Reason Analysis Of Common Fishes In Different Mangrove Forests

The heavy metal ion accumulates and remains in the organism because of the bioaccumulation and brings the potential hazards to human through the food chain at last.This article aims at sevent heavy metal elements including Zn,Cu,Cr,As,Cd,Pb,Hg and organic compound MeHg,collecting four common fishes?Liza carinata,Glossogobius olivaceus,Sillago sihama,Mugil cephalus?and their possible food from Fujian Zhangjiangkou Mangrove Reserve and Hainan Dongzhai Harbor Mangrove Reserve.Combining with the stable isotope technology,we calculate the trophic level,analyze the possible food sources of fishes;comparing heavy metal content and carbon and nitrogen stable isotope ratio content features to discuss the causes of heavy metal pollution;reseraching the transfer mechanism of heavy metals;making the ecological risk assessment to see the four fishes heavy metal pollution status and their edible quality in order to provide certain reference for ecological protection and fishes edible safety.According to the analysis and comparison,the results are as follows:1.The ?¹³C value of Liza carinata,Glossogobius olivaceus,Sillago sihama,Mugil cephalus from Dongzhai Harbor was in the range of-21.110‰ to-12.57‰,the?¹⁵N value of these fishes was in the range of 10.55‰ to 16.10‰.In Zhang Jiangkou the 813C value of these fishes was in the range of-29.69‰ to-11.88‰ whlie the ?¹⁵N value was in the range of 5.48? to 17.26?.The species differences between ?¹³C and ?¹⁵N was obvious?p<0.05?but the regional differences was not obvious?p>0.05?.2.The average trophic level of Liza carinata,Glossogobius olivaceus,Sillago sihama,Mugil cephalus from Dongzhai Harbor was 2.49 to 3.30 while Zhang Jiangkou 's average trophic level was 2.11 to 3.02.The trophic level in Sillago sihama was close to lossogobius olivaceus,whlie the Liza carinata was close to Mugil cephalus.Both the highest trophic level in two sites were the Sillago sihama,nearly one trophic level higher than the lowest trophic level of Mugil cephalus.Among the possible sources of food,the phytoplankton,algae,and POM provided most of the carbon source for fishes but sediment and mangrove plants contributed the limited carbon source.3.The characteristics of fishes' heavy metal distribution in Dongzhai harbor mangrove reserve was:Zn>As>Cr>Cu>Hg>Pb>MeHg>Cd.While in Zhangjiangkou mangrove reserve was:Zn>As>Cr>Cu>Hg>Pb>MeHg>Cd.The fish's demand for different heavy metals depended on their type.For fish's food habit,The heavy metal content in carnivorous fish?Glossogobius olivaceus,Sillago sihama?was near to the each other,phytophagous fish?Liza carinata,Mugil cephalus?was near to the each other.4.Hg and MeHg in the fish showed the biomagnification effect from two sites.Pb and Cu in the fish showed the dilution effect from Dongzhaigang Harbor while the biomagnification effect in Zhang iangkou.As,Zn,Cr,Cd,Pb significantly negatively correlated with body length?p<0.05?,which showed that the heavy metals are diluted with the growth of fish.On the contrary,Cu,Hg and MeHg showed the biological accumulation.There was no significant correlation?p>0.05?between heavy metal and length in Zhangjiangkou.Zn and Cu showed a weak negative correlations?p>0.05?,the dilution effect.5.The interaction between heavy metals in the two places was not consistent.There were some synergistic or additive effects between Hg and MeHg,Zn and Cd in Dongzhaigang Harbor,whlie Hg and Cu,Hg and As,Cu and MeHg were antagonistic.In the Zhangjiangkou area,Zn and Cd,Zn and Cu,Cu and Cd,As and Hg,As and MeHg,Hg and MeHg had some synergistic or additive effect,and the left heavy metals was not significant?p>0.05?.6.The fish quality index was low overall,only As exceeded the standard limit from two sites.However,the Hazard quotient showed that the Cr,Hg and As contents in both fish samples had some exposure risk.Taking them into account,we recommended the residents reduce the consumption and frequency of these four fishes.