论文部分内容阅读
The results of an environmental geochemical investigation on Naples and Salerno Gulfs,out of Campania plain(Southern Italy)are presented.Surface marine sediments samples were collected during three field activities: Naples and Salerno Gulfs investigation(NaSa); Bagnoli site coastal area investigation(BaSi); Ports around Naples Gulf investigation(PoNa).Elemental concentrations were determined and their interpolated distribution maps were presented.Three geochemical sources were determined for elements by analyzing the results obtained from a R-mode factor analysis: 1)geogenic contribution,2)finer deposits due to water kinetics decreasing and 3)anthropogenic activities.This result partially was presented on the single element distributions of eight concerned potential toxic elements(PTEs).Additive log-ratio transformed(ALT)elements distributions are also presented in the paper.Transformed data resolves inner dependences between variables and,theoretically,exhibited the actual distribution of each variable.In our case,the ALT transformed maps limited some heavy metals such as Cd,Cr,Pb and Zn,to their sources,enlarging the risk area of some others,such as Hg and Ni.Statistical characteristics of transformed data resulted to be more regular than original data,favoring a better class division of the distribution patters of elements.However,transformed results also introduced some difficulties into the interpretation process and they resulted to be not suitable for the estimation of environmental pollution indexes.Furthermore,if the investigation only analyzes selected elements other than entire elements,the results seem to be highly influenced by the choice of ratio-denominator.Geochemical background reference values of PTEs were determined from median value of local background.Local background values of PTEs were calculated based on fractal theories.Based on these background reference values,pollution impact analysis was applied to both BaSi and PoNa samples to illustrate pollution levels in these areas.An ecological risk assessment was applied to entire database to evaluate the overall environmental condition of the area.Environmental impacts of heavy metals estimated with PIA and ERA indexes showed that Pb,Zn,Cd and Hg are among the most risk elements in the area.