Manganese flux from continental margin sediments in a transect through the oxygen minimum

The flux of manganese from continental margin sediments to the ocean was measured with a free-vehicle, benthic flux chamber in a transect across the continental shelf and upper slope of the California margin. The highest fluxes were observed on the shallow continental shelf. Manganese flux decreased linearly with bottom water oxygen concentration, and the lowest fluxes occurred in the oxygen minimum zone (at a depth of 600 to 1000 meters). Although the flux of manganese from continental shelf sediments can account for the elevated concentrations observed in shallow, coastal waters, the flux from sediments that intersect the oxygen minimum cannot produce the subsurface concentration maximum of dissolved manganese that is observed in the Pacific Ocean.     

Deep-Sea Benthic Community Respiration: An in situ Study at 1850 Meters

The in situ oxygen uptake of sediments at 1850 meters on the continental slope south of New England is two orders of magnitude less than the uptake of sediments from shallow shelf depths. After treatment of the sediments with Formalin there was no measurable chemical oxygen uptake, which shows that the total uptake is biological (community respiration).     

Late wisconsinan sea levels on the southeast u.s. Atlantic shelf based on in-place shoreline indicators

A new interpretation of late Pleistocene sea levels on the U.S. Atlantic continental shelf is based on in-place lagoonal and salt-marsh sediments obtained from vibra-cores. These data show sea levels during the last Wisconsinan transgression were about 30 meters shallower than is indicated by existing sea-level curves.     

The coalescence of two East Australian current warm-core eddies

Two warm-core eddies coalesced in about 20 days as their centers rotated around a point on the contracting line that joined them. In the process of forming the new eddy, the subsurface isothermal-isohaline "signature" layer of one eddy was uplifted and somewhat depleted while that of the other was depressed.     

Sea levels 7,000 to 20,000 years ago

Relative sea levels for early post-Pleistocene time are best known from radiocarbon dates of sediments on the continental shelves off Texas and off northeastern United States. Differences in indicated rates of the rise of relative sea level and in depths of the shelf-breaks reveal differential vertical movement of the two shelves during this time, with the result that the Atlantic shelf has sunk with respect to the Texas shelf.     

U.s. Geological survey core drilling on the atlantic shelf

The first broad program of scientific shallow drilling on the U.S. Atlantic continental shelf has delineated rocks of Pleistocene to Late Cretaceous age, including phosphoritic Miocene strata, widespread Eocene carbonate deposits that serve as reflective seismic markers, and several regional unconformities. Two sites, off Maryland and New Jersey, showed light hydrocarbon gases having affinity to mature petroleum. Pore fluid studies showed that relatively fresh to brackish water occurs beneath much of the Atlantic continental shelf, whereas increases in salinity off Georgla and beneath the Florida-Hatteras slope suggest buried evaporitic strata. The sediment cores showed engineering properties that range from good foundation strength to a potential for severe loss of strength through interaction between sediments and man-made structures.     

Comment on "Eddy/wind interactions stimulate extraordinary mid-ocean plankton blooms"

McGillicuddy et al. (Reports, 18 May 2007, p. 1021) proposed that eddy/wind interactions enhance the vertical nutrient flux in mode-water eddies, thus feeding large mid-ocean plankton blooms. We argue that the supply of nutrients to ocean eddies is most likely affected by submesoscale processes that act along the periphery of eddies and can induce vertical velocities several times larger than those due to eddy/wind interactions.     

Mesoscale ocean eddies in the north pacific: westward propagation

A set of subsurface temperature measurements in the trade wind region northeast of Hawaii reveals large perturbations about the mean state, with zonal wavelengths of 480 kilometers. The perturbations are identified as mesoscale baroclinic eddies, and they appear to drift westward at a rate of 4.7 +/- 2.0 centimeters per second. The large-scale ( 1000 kilometers) baroclinic flow at a depth of 200 meters is 1.5 +/- 0.7 centimeters per second, also toward the west, and comparable in magnitude with the eddy drift velocity; this finding suggests that the eddy drift is strongly influenced by the large-scale flow. Mesoscale eddies have been discovered in the tropical and subtropical Atlantic Ocean. Their existence in the Pacific Ocean is now confirmed.     

东太平洋赤道海域中尺度涡的特征分析

东太平洋赤道海域是我国重要的作业渔场,中尺度涡与渔场形成和分布有着密切的联系。本研究基于流场几何的涡旋判别方法,利用2012-2018年气象卫星遥感数据对东太平洋赤道海域（85°W~125°W,5°S~5°N）的中尺度涡进行识别,分析了该海域中尺度涡旋的空间分布、半径范围、生命周期和迁移路径及速度等基本特征。研究结果显示,东太平洋赤道海域反气旋涡的数量要多于气旋涡的数量;涡旋的生命周期较短,绝大多数不超过一周;涡旋的半径主要集中在250~310 km,迁移速度主要集中在6~18 m/s,迁移距离为25~50 km;在靠近南北纬5°的海域表现出两条涡旋活动较为频繁的“热带区域”,而在纬度为零的海域几乎没有涡旋存在。同时,涡旋的生命周期和半径表现出明显的年间变化。该研究成果为深入分析东太平洋赤道海域渔场形成、时空分布和开展渔情预报提供了基础。     

Eddy/wind interactions stimulate extraordinary mid-ocean plankton blooms

Episodic eddy-driven upwelling may supply a significant fraction of the nutrients required to sustain primary productivity of the subtropical ocean. New observations in the northwest Atlantic reveal that, although plankton blooms occur in both cyclones and mode-water eddies, the biological responses differ. Mode-water eddies can generate extraordinary diatom biomass and primary production at depth, relative to the time series near Bermuda. These blooms are sustained by eddy/wind interactions, which amplify the eddy-induced upwelling. In contrast, eddy/wind interactions dampen eddy-induced upwelling in cyclones. Carbon export inferred from oxygen anomalies in eddy cores is one to three times as much as annual new production for the region.     

Radiuin-226 and radon-222 in the coastal waters of west Florida: high concentrations and atmospheric degassing

On the central portion of the west Florida continental shelf, radionuclide activities show unusually wide variations: radium-226 activities up to 350 disintegrations per minute per 100 liters, radon-222 activities up to 1300 disintegrations per minute per 100 liters, and deficiencies of radon-222 as low as -10 disintegrations per minute per 100 liters. Florida's phosphate-rich strata seerm to be the principal source of the radionuclides, with the transfer occurring directly from sediments or indirectly in streams, ground-water flow, and geothermal springs. Winter storm fronts may enhance radon degassing in the shelf waters.     

Yukon River: Evidence for Extensive Migration during the Holocene Transgression

The shift of the Yukon River, during the Holocene sea-level transgression, from south of Nunivak Island during the Wisconsin maximum to its present location (a distance greater than 300 kilometers) is indicated by remanent channels, distinct subbottom structures, deltaic sediments, and anomalous rates of sediment accumulation on the continental shelf of the east-central Bering Sea. These features were produced as the ancestral river migrated northward across the easternmost part of this area before 11,000 years ago.     

Distributions of phytoplankton blooms in the southern ocean

A regional pigment retrieval algorithm for the Nimbus-7 Coastal Zone Color Scanner (CZCS) has been tested for the Southern Ocean. The pigment concentrations estimated with this algorithm agree to within 5 percent with in situ values and are more than twice as high as those previously reported. The CZCS data also revealed an asymmetric distribution of enhanced pigments in the waters surrounding Antarctica; in contrast, most surface geophysical properties are symmetrically distributed. The asymmetry is coherent with circumpolar current patterns and the availability of silicic acid in surface waters. Intense blooms (>1 milligram of pigment per cubic meter) that occur downcurrent from continental masses result from dissolved trace elements such as iron derived from shelf sediments and glacial melt.     

冷链运输对哈密瓜品质及腐烂率的影响

[目的]研究冷链运输对哈密瓜运输品质、腐烂率及和货架期的影响,解决精品哈密瓜运输过程品质劣变,腐烂严重、货架期短的问题.[方法]以哈密瓜(Cucumis melo L ssp.melo Pang)金龙为试材,采用1-甲基环丙烯(1 - MCP)处理,冷链运输,研究冷链运输对不同可溶性固形物含量甜瓜果实运输品质、腐烂率、商品率以及货架品期的影响.[结果]冷链运输对甜瓜可溶性固形物含量的变化影响较小,延缓果实硬度的下降.各成熟度甜瓜,采用冷链运输商品率较对照高40;,货架期商品率高30;;冷链运输甜瓜货架期比常温运输延长2d.甜瓜成熟度过高,运输及货架期商品率低,腐烂率高.[结论]冷链运输延缓甜瓜运输过程果实衰老,保持品质,延长货架期,降低腐烂率.     

Freshwater peat on the continental shelf

Freshwater peats from the continental shelf off northeastern United States contain the same general pollen sequence as peats from ponds that are above sea level and that are of comparable radiocarbon ages. These peats indicate that during glacial times of low sea level terrestrial vegetation covered the region that is now the continental shelf in an unbroken extension from the adjacent land areas to the north and west.     

Biological uptake of dissolved silica in the Amazon river estuary

Approximately 25 percent of the dissolved silica carried by the Amazon River is depleted through diatom production in the inner estuary. Annual production of opaline frustules is estimated to be 15 million tons. However, few diatoms accumulate in modern shelf sediments and chemical recycling appears to be slight. Instead, many frustules apparently are transported landward into the river system, where they deposit in dunes and layers on and within mud and sand bars.     

Deep-sea species diversity: decreased gastropod diversity at abyssal depths

Gastropod species diversity is low on the continental shelf, high on the continental slope and abyssal rise, and then decreases with increasing distance out onto the abyssal plain. Increased diversity below the continental shelf has been attributed to increased environmental stability. Decreased diversity on the abyss may result from extremely low productivity.     

Migrations and growth of deep-sea lobsters, Homarus americanus

In distinct contrast to the restricted movements of coastal stocks of lobsters (Homarus americanus), those inhabiting the outer continental shelf undertake extensive seasonal migrations. Of 5710 tagged lobsters released on the outer continental shelf off New England from April 1968 to June 1969, 400 had been recaptured by April 1970. The distribution of the recoveries demonstrated shoalward migration in spring and summer and a return to the edge of the shelf in fall and winter. Deep-sea lobsters have a faster rate of growth than coastal lobsters; growth increments at molting and the frequency of molting are greater.     

Fish population and behavior revealed by instantaneous continental shelf-scale imaging

Until now, continental shelf environments have been monitored with highly localized line-transect methods from slow-moving research vessels. These methods significantly undersample fish populations in time and space, leaving an incomplete and ambiguous record of abundance and behavior. We show that fish populations in continental shelf environments can be instantaneously imaged over thousands of square kilometers and continuously monitored by a remote sensing technique in which the ocean acts as an acoustic waveguide. The technique has revealed the instantaneous horizontal structural characteristics and volatile short-term behavior of very large fish shoals, containing tens of millions of fish and stretching for many kilometers.     

Evidence for upwelling of corrosive "acidified" water onto the continental shelf

The absorption of atmospheric carbon dioxide (CO2) into the ocean lowers the pH of the waters. This so-called ocean acidification could have important consequences for marine ecosystems. To better understand the extent of this ocean acidification in coastal waters, we conducted hydrographic surveys along the continental shelf of western North America from central Canada to northern Mexico. We observed seawater that is undersaturated with respect to aragonite upwelling onto large portions of the continental shelf, reaching depths of approximately 40 to 120 meters along most transect lines and all the way to the surface on one transect off northern California. Although seasonal upwelling of the undersaturated waters onto the shelf is a natural phenomenon in this region, the ocean uptake of anthropogenic CO2 has increased the areal extent of the affected area.