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.

Export production of particles to the interior of the equatorial Pacific Ocean during the 1992 EqPac experiment

Abstract: Twenty-four time-series, moored sediment traps were deployed between 2/2/92 and 1/27/93 along 140°W at 9°N, 5°N, 2°N, 0°, 2°S, 5°S and 12°S at water depths of approximately 1200 m and 2200 m, and 700 m above the bottom. The opening/closing of the traps was synchronized at 17-day periods, for 21 events, covering a total of 357 days. The average annual particle flux in the ocean's interior (2.2 to 4.4 km deep) from 5°N to 5°S was 28.5 g m−2 year−1, with 34.8 g−2 year−1 the maximum annual flux at the equator. Sixty-six per cent of settling particles were carbonate; 24% biogenic SiO2 and 5% organic carbon. The onset of tropical instability waves, marking the year's El Nino/post-El Nino boundary, was associated with a succession of intervals with greater organic carbon and opal at 5°N, 2°S and 5°S that occurred synchronously with a meridional oscillation of instability waves, while net carbon flux during El Nino and post-El Nino periods did not change. Although organic carbon flux increased at 5°N, 2°S and 5°S during the post-El Nino period, it was counterbalanced by decreases at the upwelling stations (2°N and the equator), resulting in no net carbon flux increase across the 5°N to 5°S region. In February/March 1992, only 0.34% of the organic carbon fixed by primary production over the 5°N to 5°S zone arrived in the ocean's interior. In August/September that year, zonal average of organic carbon flux increased slightly to 0.5% of primary production. Very little carbon reached the interior depths of the upwelling stations; however, the fraction of export was higher at the 5°N, 2°S and 5°S stations. The pattern of variability of particle flux at the shallow depths was observed also in deeper traps, without temporal offsets, suggesting a settling particle residence time shorter than the 17-day timeseries resolution during most of this experiment.

The time-transgressive termination of the African Humid Period

Abstract: During the early to mid-Holocene, Africa was more humid than today. Precipitation reconstructions from across Africa suggest that the termination of humidity was spatially variable, moving towards progressively lower latitudes.

Chapter 158 Marine chemistry and geochemistry of the lanthanides

Abstract: Publisher Summary This chapter discusses the characteristics and properties of lanthanides in seawater and presents the rationale for studying the lanthanide composition of natural waters. The lanthanides are composed of a group of fourteen elements (La, Ce, Pf, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu). There are anthropogenic sources of lanthanides to the atmosphere (and presumably to the ocean) in the form of particles produced during the cracking of oil and the combustion of oil and gasoline products. A major objective of chemical oceanography is to understand processes controlling the concentration, distribution, speciation, and flux of elements in the oceans. The chapter describes and discusses lanthanide distributions in the oceans and the biogeochemical and physical processes responsible for these distributions. It presents the profiles of lanthanide concentrations in the water column and their variations within and between ocean basins. The redox geochemistry of Ce as revealed by vertical and horizontal variations in the Ce anomaly is discussed. The inter-oceanic mass fractionation of the strictly trivalent lanthanides is also described.

Production of strong, extracellular Cu chelators by marine cyanobacteria in response to Cu stress

Abstract: Copper speciation in the upper marine water column is dominated b>, strong ligands thought to be of recent biological origin. Cultures of the marine cyanobacteria Synechococcu.? spp., a ubiquitous and important group of phytoplankton highly sensitive to Cu toxicity, were previously shown to produce chelators comparable in strength to those detected in the water column. Here we shoyw that cultures of Synechococcus exposed to toxic concentrations of Cu produce an extracellular ligand with a binding constant comparable to constants for ligands found in the water column. Coordination of Cu by this compound decreases the concentration of free cupric ion (the toxic form) in the culture media to le-rels that do not inhibit growth. A tight linear correlation between chelator and Cu concentration suggests l.hat production of this substance may be regulated by the concentration of free Cu in the media in a feeldback mechanism. Similarly, the concentrations of Cu and Cu-binding ligands in the water column are o?ten closely related. These results suggest that cyanobacteria modify Cu chemistry in seawater, creating conditions more favorable for growth.

Beaked Whales Respond to Simulated and Actual Navy Sonar

Abstract: Beaked whales have mass stranded during some naval sonar exercises, but the cause is unknown. They are difficult to sight but can reliably be detected by listening for echolocation clicks produced during deep foraging dives. Listening for these clicks, we documented Blainville's beaked whales, Mesoplodon densirostris, in a naval underwater range where sonars are in regular use near Andros Island, Bahamas. An array of bottom-mounted hydrophones can detect beaked whales when they click anywhere within the range. We used two complementary methods to investigate behavioral responses of beaked whales to sonar: an opportunistic approach that monitored whale responses to multi-day naval exercises involving tactical mid-frequency sonars, and an experimental approach using playbacks of simulated sonar and control sounds to whales tagged with a device that records sound, movement, and orientation. Here we show that in both exposure conditions beaked whales stopped echolocating during deep foraging dives and moved away. During actual sonar exercises, beaked whales were primarily detected near the periphery of the range, on average 16 km away from the sonar transmissions. Once the exercise stopped, beaked whales gradually filled in the center of the range over 2–3 days. A satellite tagged whale moved outside the range during an exercise, returning over 2–3 days post-exercise. The experimental approach used tags to measure acoustic exposure and behavioral reactions of beaked whales to one controlled exposure each of simulated military sonar, killer whale calls, and band-limited noise. The beaked whales reacted to these three sound playbacks at sound pressure levels below 142 dB re 1 µPa by stopping echolocation followed by unusually long and slow ascents from their foraging dives. The combined results indicate similar disruption of foraging behavior and avoidance by beaked whales in the two different contexts, at exposures well below those used by regulators to define disturbance.