Settling particl
es and bottom sediments collected at 1,2.5, and 4 km off the metropolitan Buenos Air
es coast inthe Río de la Plata were analyzed to evaluate the sourc
esand toxicity of r
esolved (PAHs) and unr
esolved (ARO
UCM)aromatic hydrocarbons. PAHs (0003-2.1
![](/imag<font color=)
es/entiti
es/mgr.gif">g g
-1) and AROUCM(0.01-78
![](/imag<font color=)
es/entiti
es/mgr.gif">g g
-1) pr
esented the high
est concentrationsnear the Buenos Air
es port and sewer and decreasing valu
esup- and downstream and along on- and offshore gradients.Sediment traps deployed in the Central area revealedlarge aromatic flux
es (1.3 ± 1.5 and 31 ± 47 mg m
-2 day
-1for PAHs and AROUCM). The composition of sedimentaryPAHs was dominated by uniformly distributed highmolecular weight pyrogenic PAHs (53 ± 11% fluoranthene,pyrene, and heavier PAHs), followed by diageneticallyderived perylene more abundant in l
ess polluted sit
es(29 ± 15%) and lower molecular weight petrogenic PAHs(18 ± 7.1% phenanthrene, anthracene, and methylatedcompounds), which covaried inversely with perylene. PAHdiagnostic ratios indicated a stronger influence ofpetrogenic discharg
es close to the shore and the prevalenceof combustion of fossil fuels and vehicle emissions overwood in offshore sediments. Sediment cor
es showedsustained hydrocarbon levels with decreasing proportionof petrogenic PAHs and relative enrichment of pyrogeniccomponents and perylene down to 20-cm depth. PAH toxicityass
essment by sediment quality guidelin
es (SQG) and dioxin-equivalent factors (PAH TEQ: 0.08-395 pg g
-1 dw)identified 1-2.5 km sediments close to the port and seweras the most affected area. According to SQG, dibenz[
a,
h]anthracene and pyrene were the most critical PAHs,followed by benzo[
a]pyrene, benz[
a]anthracene, and chrysene.In contrast, PAH TEQs were dominated by indeno[1,2,3-
cd]pyrene, benzo[
k]fluoranthene, benzo[
a]pyrene, perylene,and benz[
a]anthracene which accounted for an average86 ± 5.7% of total TEQs.