| The coastal area of Rudong is located in the southern wings of the northern Jiangsu radial sand ridges.The sedimentary dynamic environment is complicated.With the rapid economic development in recent decades and the rapid development of human development activities,a large amount of pollutants have been transported to the area.The environment has caused adverse effects,and the study area is also an important marine fishery economic production area.Therefore,it is of great significance to study the pollutant distribution law and influencing factors in this area.This paper analyzes and tests the sediments of 32 surface sediments to partition the current sedimentary dynamic environment.The cocentration spatial distribution,sources apportionment and human health risks of polycyclic aromatic hydrocarbons(PAHs)in the sediments of the study area were ascertained.With the help of Geographically Weighted Regression Model(GWR)to establish a regression relationship between sediment PAHs and different influencing factors,combined with a two-dimensional hydrodynamic model to reveal the dynamic causes of the distribution of PAHs in the study area,and to establish the migration law of PAHs in the coastal areas of Rudong.Providing a scientific basis for guiding the local offshore fishery production activities and the prevention and treatment of coastal marine environmental pollution.The main research contents and conclusions of this paper are as follows:(1)Based on the datas of grain size composition and parameter analysis of 32 surface sediments in the coastal areas of Rudong in Jiangsu Province,the distribution characteristics of sediment types,grain size components and grain size parameters were analyzed.In addition,combined with the Folk&Ward's nomenclature,the Q-type system cluster analysis method and the tidal dynamic characteristics of the study area,the coastal areas of Rudong were divided into three sub-areas,namely the near-shore tidal flat and sand ridge area,the tidal channel area and the edge region of sand ridge,respectively.The results indicated that the distribution of grain size in surface sediments has obvious spatial differences in the coastal areas of Rudong by the influence of material source and sedimentary dynamics environmental.There are three sediment types in surface sediments in the coastal areas of Rudong,with sandy silt as the main content,the average content of 50%;followed by silty sand,the average content of 46.87%;the sand content have least proportion,the average content of 3.13%.The mean grain size of surface sediment are between 25.65?m?171.72?m,and the average of 70.61?m.In addition,the trend of spatial distribution is consistent with the change of sand content.Sorting coefficient,skewness,and kurtosis are characterized by poor-difference,near-symmetry-extremely negative,sharp-very sharp,respectively.In spatial,1)The nearshore tidal flat-sand ridge area,there are abundance of sand content and coarser of grain size in sediments by water depth of shallow,sedimentary and erosion dynamic changes of complex;2)The tidal channel area,there are more clay content and finer grain size in sediments by the channel's depth of large,the bottom affected by hydrodynamics of less;3)The edge region of sand ridge,there are deep water depth and little effected by tidal current of relatively stable sedimentary environment.(2)Studies of PAHs in sediments have shown that the concentration of 16 PAHs ranges from 2.2-46.6 ng g-1(with mean value of 8.36 ng g-1),which is lower than other coastal areas.From a composition point of view;from a spatial point of view,the spatial distribution of PAHs showed a decreasing trend from southeast to northwest,and the near-shore value was low and the deep-water area value was high.PMF results show that petroleum and industrial sources,biomass and coal combustion sources,and maritime and vehicle traffic sources are the main sources of PAHs,and their contribution rates account for 28.9%,25.5%,24.7%,and 20.9%of the total PAHs,respectively.The incremental lifetime cancer risk(ILCR)of PAHs in sediments is<1×10-6,and the cancer risk of every age group is within an acceptable range,so the current consumption of seafood in this area does not pose a health risk.(3)The content of PAHs in the product is significantly different from that of clay and TOC.Combining with two-dimensional hydrodynamic model and GWR,this paper explores the influencing factors of PAHs distribution in sediments,revealing the influence of sedimentary dynamic environment on PAHs distribution.The spatial distribution forms of pahs pollution in different sedimentary dynamic environments were different,and the regression coefficients of clay and TOC and Local R showed an obvious progressive trend in different sedimentary environments,which showed the restriction of GWR fitting effect in sedimentary dynamic environments.Clay as the dominant factor of affect the distribution of PAHs is more,its content and distribution of limited by sedimentary dynamic environment,there are significant differences in different sedimentary environment,combined with 2D hydrodynamic model for the tidal current and sediment transport in the studied area is simulated,the dominant sedimentary dynamic environment area of sediment distribution pattern,and then presents the match the current sedimentary dynamic environment of the spatial distribution characteristics of PAHs. |
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