No abstract

Temporal trends of polychlorinated biphenyls (PCBs) were studied for detritivorous fish (1996–2017) and settling material (2002–2017) from polluted Buenos Aires coast and for a dated sediment core (1970–2013) from the outer Río de la Plata estuary. In spite of contrasting concentrations [5.3 ± 6.3 μg·g–1 dry weight (dw) for fish, 48 ± 26 ng·g–1 dw for settling material, and 1.5 ± 0.7 ng·g–1 dw for core], all three revealed exponentially decreasing trends over time (97%, 83%, and 83%, respectively). Time trends showed peak maxima coincident with Argentina’s period of maximum PCB usage in 1973–1980 (80 cm depth in the core) and pulse discharges related to PCB banning in 2001–2002 (fish) with a lighter signature enriched in less persistent tri- and tetrachlorobiphenyls. The log–linear PCB time trends compare well with the predicted decrease for a high emission scenario from global emission data; the best fit was observed for the less impacted sediment core (−2%·year–1 versus −3%·year–1 for emission scenario). Steeper slopes are observed for the more polluted settling material (−5%·year–1) and especially for fish, in which the background decline trend tripled after the 2001 PCB pulse (from −7%·year–1 to −21%·year–1). These PCB time trends in related environmental compartments from contrasted sites provide rare evidence for evaluating the effectiveness of control measures in southern South America.

Atmospheric Polychlorinated Biphenyls (PCBs: ∑ 42 congeners) collected by polyurethane passive samplers (PAS-PUFs) in 29 stations from July 2010 to February 2014 (n=141) in the most productive and populated Southern Rio de la Plata area in Argentina were evaluated to assess concentration gradients, potential sources and compositional profiles related to different land use and urbanization. On a global scale, total airborne PCBs concentrations are low/very low (below detection limit to 937pgm) and show a significant potential correlation with urban scale increasing 2.5 times each 10 times increase of population reflecting the primary role of urbanization controlling PCB emissions. Compositional patterns evaluated by principal component analysis (PCA) of individual congeners indicated that highly populated atmospheres are enriched in lighter, more volatile tri, tetra and penta chlorine congeners of lighter Aroclor mixtures (from 1242 to 1254) suggesting actual emission of fresh PCBs signatures from sealants, combustion and/or electrical equipment. Sub urban and rural sites show a gradual transition to heavier Aroclor mixtures (from 1254 to 1260) with predominance of more persistent hexa and hepta PCBs indicating an aged background signal resulting from long range transport and/or re-emission from historic reservoirs such as soils.