Woods Hole Oceanographic Institution

About: Woods Hole Oceanographic Institution is a nonprofit organization based out in Falmouth, Massachusetts, United States. It is known for research contribution in the topics: Population & Mantle (geology). The organization has 5685 authors who have published 18396 publications receiving 1202050 citations. The organization is also known as: WHOI.

Review of flow rate estimates of the Deepwater Horizon oil spill

Abstract: The unprecedented nature of the Deepwater Horizon oil spill required the application of research methods to estimate the rate at which oil was escaping from the well in the deep sea, its disposition after it entered the ocean, and total reservoir depletion. Here, we review what advances were made in scientific understanding of quantification of flow rates during deep sea oil well blowouts. We assess the degree to which a consensus was reached on the flow rate of the well by comparing in situ observations of the leaking well with a time-dependent flow rate model derived from pressure readings taken after the Macondo well was shut in for the well integrity test. Model simulations also proved valuable for predicting the effect of partial deployment of the blowout preventer rams on flow rate. Taken together, the scientific analyses support flow rates in the range of ∼50,000–70,000 barrels/d, perhaps modestly decreasing over the duration of the oil spill, for a total release of ∼5.0 million barrels of oil, not accounting for BP's collection effort. By quantifying the amount of oil at different locations (wellhead, ocean surface, and atmosphere), we conclude that just over 2 million barrels of oil (after accounting for containment) and all of the released methane remained in the deep sea. By better understanding the fate of the hydrocarbons, the total discharge can be partitioned into separate components that pose threats to deep sea vs. coastal ecosystems, allowing responders in future events to scale their actions accordingly.

Helium isotopic systematics of oceanic islands and mantle heterogeneity

Abstract: Isotopic variations in oceanic igneous rocks provide important constraints on models of oceanic mantle structure. Of particular interest is the global negative correlation between 87Sr/86Sr and 143Nd/144Nd, which has been used to estimate ‘bulk earth’ values1–3 for 87Sr/86Sr, 87Rb/88Sr and 143Nd/144Nd. Simple two-reservoir models have failed to explain all the isotopic variations, however, because of the complicated trends in Pb isotopes4–6. This has led to suggestions that recycled oceanic crust or sediments must be considered in these models7–9. We report here the results of helium isotopic analyses in basaltic phenocrysts from the islands of Gough and Tristan da Cunha. Because basalts from the islands lie near bulk earth on the Sr–Nd correlation diagram3, the study was initiated to characterize the helium isotopic signature of this component. Whereas the 3He in mantle gases is mostly primordial, the 4He is primarily radiogenic, having been produced by decay of 238U, 235U and 232Th. High 3He/4He ratios in igneous rocks therefore indicate primordial volatiles10,11. We believe that the present results are inconsistent with the notion that the mantle beneath Gough and Tristan da Cunha is primitive or undepleted relative to mid-ocean ridge basalt (MORB). Helium isotopic results on basaltic glasses and phenocrysts from the rift zone of Kilauea confirm the previously reported high values from this area12–15. We also report new analyses from Loihi Seamount (40km south-east of Kilauea), which does seem to be derived from a more primitive source. When these data are combined with values for MORBs (from ref. 16) and plotted with respect to 87Sr/86Sr, the observed trends offer insight into the different source regions for oceanic island basalts and the nature of mantle heterogeneity.

Wave-influenced deltas: geomorphological implications for facies reconstruction

Abstract: A process-based facies model for asymmetric wave-influenced deltas predicts significant river-borne muds with potentially lower quality reservoir facies in prodelta and downdrift areas, and better quality sand in updrift areas. Many ancient barrier-lagoon systems and ‘offshore bars’ may be better reinterpreted as components of large-scale asymmetric wave-influenced deltaic systems. The proposed model is based on a re-evaluation of several modern examples. An asymmetry index A is defined as the ratio between the net longshore transport rate at the mouth (in m 3 year )1 ) and river discharge (in 10 6 m 3 month )1 ). Symmetry is favoured in deltas with an index below 200 (e.g. Tiber, lobes of the Godavari delta, Rosetta lobe of the Nile, Ebro), whereas deltas with a higher index are asymmetric (e.g. Danube ‐ Sf. Gheorghe lobe, Brazos, Damietta lobe of the Nile). Periodic deflection of the river mouth for significant distances in the downdrift direction occurs in extreme cases of littoral drift dominance (e.g. Mahanadi), resulting in a series of randomly distributed, quasi-parallel series of sand spits and channel fills. Asymmetric deltas show variable proportions of river-, wave- and tide-dominated facies both among and within their lobes. Bayhead deltas, lagoons and barrier islands form naturally in prograding asymmetric deltas and are not necessarily associated with transgressive systems. This complexity underlines the necessity of interpreting ancient depositional systems in a larger palaeogeographic context.