Distribution Characteristics And Ecological Risk Assessment Of Polycyclic Aromatic Hydrocarbons In The Beibu Gulf

In order to understand the pollution status of polycyclic aromatic hydrocarbons in seawater,sediments and organisms in the Beibu Gulf,a total of27 seawater samples,23 sediment samples and 36 biological samples were collected.Among them,15 water samples and 11 sediment samples were collected from the rivers,and 12 seawater and sediment samples were collected from the coastal zone.The content of 16 excellent PAHs was determined by gas chromatography-mass spectrometry(GC/MC)analysis.Their distribution characteristics,source analysis and ecological risk assessment were discussed..The research results are as follows:(1)The summer ?16PAHs is significantly higher than the coastal water content.The rivers entering the sea in winter were slightly higher than those in the coastal zone,but the difference was not significant(t-test,p>0.05).Compared with different seasons,the ?16PAHs in the rivers and coastal waters were significantly higher than those in summer(t test,p<0.01).In general,the PAHs in the two waters in the two seasons were mainly low-ring aromatics,which accounted for more than 97% of the total.In the same season,the proportion of polycyclic aromatic hydrocarbons in the estuary and coastal watersis similar,indicating that the two have the same source,and the river has a greater impact on coastal pollution.None of the 16 PAHs components in the sediment were detected.The content of ?16PAHs ranged from 2.39 to 358.62ng/g,and the average content was 109.76 ng/g.The content of PAHs in the sediments of the rivers is significantly higher than that in the coastal zone.The PAHs in the rivers are mainly composed of 3-ring,4-ring and 5-ring aromatics,which account for more than 83% of the total rivers.The composition of PAHs in coastal sediments is similar to that of rivers in the sea.It is also dominated by3-ring,4-ring and 5-ring aromatics,accounting for more than 80% of the total rivers.The biological samples are mainly low-ring aromatic hydrocarbons.Among them,the proportion of the two rings in crabs and shrimps is significantly higher than that of fish and shellfish;on the contrary,the proportions of the three rings and four rings in fish and shellfish are higher than that of crabs.Classes and shrimps.The proportion of 5-ring and 6-ring PAHs is low.(2)Among the four rivers tested,the highest content of PAHs in summer seawater is the Nanliu River.The flow of the four rivers PAHs into the sea reached 826kg/a.The Nanliu River PAHs have the highest flux into the sea and have the greatest impact on the Beibu Gulf.Different from water,the detection rate of 16 PAHs in sediments is 100%,and the highest content of 4 rivers entering the sea is Qin River.The PAHs detected in the four rivers entering the sea were mainly 3~5 rings,and the proportion of PAHs above 4 rings was higher.Preliminary determination of PAHs pollution in sediments is biased towards fossil fuel combustion.(3)Analysis of the sources of PAHs in seawater,sediments and organisms in the Beibu Gulf by isomer ratio and principal component analysis.The results show that the sources of polycyclic aromatic hydrocarbons in the surface seawater in summer are mainly combustion and petroleum.the source of polycyclic aromatic hydrocarbons in the surface waters of winter is mainly combustion.The sediments are burning and oil,and they are more burning.In vivo PAHs are mainly derived from oil pollution.(4)A comprehensive ecological risk assessment of PAHs in the Beibu Gulf waters shows that the ecological risk of the waters in the region is low.The components of PAHs in the surface sediments of the Beibu Gulf are much lower than the ecological risk effect(ERL)and the rare effect level(REL).However,five PAHs with no minimum safety value were detected in the study area,indicating that although the area is a low ecological risk area,there are still some potential ecological risks.Bap was detected in all organisms,but its content was far below the internationally accepted upper limit of edible standards.The PAHs in vivo were also within the risk level of carcinogenicity,indicating that the creatures in the Beibu Gulf are still at present.Within the edible safety range,there is less threat to human health.