Oil spill in the Río de la Plata estuary, Argentina: 1. Biogeochemical assessment of waters, sediments, soils and biota

Aliphatic (ALI) and aromatic (ARO) hydrocarbon concentrations, composition and sources were evaluated in waters, sediments, soils and biota to assess the impact of 1000 tons of oil spilled in Río de la Plata coastal waters. Total ALI levels ranged from 0.4–262 μg/l in waters, 0.01–87 μg/g in sediments, 5–39 μg/g in bivalves, 12–323 μg/g in macrophytes to 948–5187 μg/g in soils. ARO varied from non-detected 10 μg/l, 0.01–1.3 μg/g, 1.0–16 μg/g, 0.5–6.9 μg/g to 22–67 μg/g, respectively. Offshore (1, 5, 15 km) waters and sediments were little affected and contained low background hydrocarbon levels reflecting an effective wind-driven transport of the slick to the coast. Six months after the spill, coastal waters, sediments, soils and biota still presented very high levels exceeding baseline concentrations by 1–3 orders of magnitude. UCM/resolved aliphatic ratio showed a clear trend of increasing decay: coastal waters (3.3)n-C23) and petrogenic/pyrogenic relationship (methylated/unsubstitued PAH) discriminated the samples according to the different degree of impact. The following paper present the results of the study of the progress of hydrocarbon disappearance in sediments and soils 13 and 42 months after the spill.