摘要：The extensive release of oil during the 2010 Deepwater Horizon spill in the northern Gulf of Mexico perturbed the pelagic ecosystem and associated sinking material.To gauge the recovery and post-spill baseline sources, we measured Δ14C, δ13C and δ34S of sinking particles near the spill site and at a reference site and natural seep site.Particulates were collected August 2010–April 2016 in sediment traps moored at sites with depths of 1160–1660 m.Near the spill site, changes in Δ14C indicated a 3-year recovery period, while δ34S indicated 1–2 years, which agreed with estimates of 1–2 years based on hydrocarbon composition.Under post-spill baseline conditions, carbon inputs to sinking particulates in the northern Gulf were dominated by surface marine production (80–85%) and riverine inputs (15–20%).Near the spill site, Δ14C values were depleted in October 2010 (–140 to –80‰), increasing systematically by 0.07 ± 0.02‰ day–1 until July 2013 when values reached –3.2 ± 31.0‰.This Δ14C baseline was similar to particulates at the reference site (3.8 ± 31.1‰).At both sites, δ13C values stayed constant throughout the study period (–21.9 ± 0.5‰ and –21.9 ± 0.9‰, respectively).δ34S near the spill site was depleted (7.4 ± 3.1‰) during October 2010–September 2011, but enriched (16.9 ± 2.0‰) and similar to the reference site (16.2 ± 3.1‰) during November 2012–April 2015.At the seep site, Δ14C values were –21.7 ± 45.7‰ except during August 2012–January 2013 when a significant Δ14C depletion of –109.0 ± 29.1‰ was observed.We interpret this depletion period, also observed in δ13C data, as caused by the incorporation of naturally seeped oil into sinking particles.Determination of post-spill baselines for these isotopic signatures allows for evaluation of anthropogenic inputs in future.
关键词：Deep Water Horizon Oil Spill;radiocarbon;isotopes;Gulf of Mexico;sinking particulates;sediment trap;
