A salinometer for use in brackish water

In principal this salinometer is a battery composed of a pair of dissimilar metals immersed in the brackish water of the field as an electrolyte. Between these dissimilar metals there exists a potential difference which is practically independent of the concentration of salts in the electrolyte over a very wide range. However, the salt concentration has a marked effect upon the conductivity of the electrolyte. If the measuring circuit has constant resistance, the only change of resistance in the total circuit is that due to the change of conductivity of the water in which the cell is immersed. Since the driving EMF is essentially constant, the current fl.owing in the circuit is a measure of the conductivity of the water sample

An electromagnetic method for measuring the velocities of ocean currents from a ship under way

During the past four years a deliberate effort has been made at the Woods Hole Oceanographic Institution to devise methods of kinematic observation generally suited to the needs of oceanographers. One result of this work, the electromagnetic method, has been brought from the experimental stage to one of useful maturity. Many of the theoretical potentialities of the method are still to be explored and developed. Nevertheless it seems likely that this remaining work may be done more soundly if present developments of the theory and instrumentation are made available for use and evaluation by, others. These studies in methods of kinematic observation have been supported mainly under the provisions of Bureau of Ships Contract NObs-2083, and Office of Naval Research Contract N6onr-277-1. This support and the assistance of the Naval Ordnance Laboratory, the Hydrographic Office (Oceanographic Division), the United States Coast Guard, and the David Taylor Model Basin of the United States Navy is gratefully acknowledged

Some current meters designed for suspension from an anchored ship

Current velocities measured by means of instruments suspended from shipboard may err significantly if the ship\u27s motion at anchor is permitted to tow the instruments through the water while observations are in progress. Two current meter designs are described which employ a propeller linkage by electromagnetic induction to permit continuous observation of current velocity through, and to determine the extent of, the periods when the anchored ship is essentially at rest. The motions of an anchored ship are described

Hudson '70 : gravity observations 62.9S̊ - 57.5N̊ along 150W̊

To provide geoidal topography over the world oceans, a radar altimeter carried by earth satellite is planned. Ground truth calibration will be provided by a grid comprised of the equatorial belt and meridional traverses along the 30°W and 150°W meridians. Ground truth topography is derived from gravity values measured along these traverses. This report presents the free air gravity values and the computed free air anomalies obtained from 62.9°S to 57.5°N along the 150°W meridian.Supported by the Office of Naval Research under Contract N00014-66-C0241; NR 083-004

Seasonal performance of a brine pond solar heat collector in New England

The modified 20 metric ton, 20 m2 area Bloch-Tabor brine pond built on the premises of the New Alchemy Institute, Hatchville, Massachusntts, under Woods Hole Oceanographic Institution auspices has been in operation since early October 1976 through one of the coldest winters in recent New England history. Despite a "cold" start in October 1976 the core temperature declined only to 24°C in January-February 1977, reached a summer peak of 58 C in August 1977 and is now showing seasonal decline . Generally speaking, the pond has maintained a temperature about 20°C above ambient; showing only very sluggish responses to weather changes and a smooth response to seasonal changes of insolation and average wind speed. The pond, though small, has been operated in an unsheltered mode to see whether very large ponds (too large to be covered) could perform usefully in New England. As a result the open pond not only suffered evaporative losses and wind-mixing of the fresh water cap overlying the brine, but, when iced over, collected snow. Exposure to the elements also permitted accumulation of leaves, pollen, and dust on the surface which cast shadows. Almost daily cleaning was necessary but easily done with a drop of dishwashing detergent on the surface and a scoop net. The pond operated at an average efficiency of 24% (total daily output/daylight input x 100%) . The pond differs from the Bloch-Tabor design in utilizing coal as a black body absorber and brine concentrations of Calcium Chloride Hexahydrate near 45% to raise the refractive index to 1.42 and thus enhance the "fish-eye" or whole-sky radiation-trap effect. As a result the pond could acquire and trap radiation on cloudy as well as clear days to such good effect that it is difficult to distinguish between clear and overcast days in the recording thermograph records. Rainfall has a cooling effect from which recovery is rapid, and also "tops up" and freshens the sweet water cap over the brine. Precipitation has just about balanced evaporative losses from the surface since excesses overflow and P - E is generally positive in New Enqland. The experiment has been generally successful from the physical point of view (radiant heating of homes, for example), but its biological performance is marginal in mid-winter . Tropical species of plankton feeders, such as Talapia, grow best in water temperatures near 27°C which the pond at 24°C cannot supply in the coldest months. Anaerobic digesters for bioconversion of organic wastes into high grade fuels and fertilizers operate best at 35°C which, again, are not within the capabilities of the pond in mid-winter. Water plants, algae and the nitrogen-fixing bacteria associated with Azolla (water ferns) survive and reproduce at 24°C and can thus be held over in winter, but 30°C or so would improve their vitality. Obviously, some form of increased heat storage capacity, with very long time constants, is required.As a result of these findings and experiences an altogether different approach to solar heat collection and storage has been developed in which the heat excesses of summer are collected and stored below ground for use in winter: the annual-cycle, groundwater heat storage system. Preparations are being made to drive wells to and into the phreatic zone so as to pump several hundred-thousand gallons of cold groundwater to the surface for solar heating to about 45°C in summer, and return the heated water to the groundwater table for storage as a warm, buoyant lens for heat recovery in winter. The practicality of such a plan has been given careful study with much help from the geologists, hydrologists, and environmentalists of the U. S. Geological Survey, Environmental Protection Agency , and the National Water Well Association. Computer models of the "thermal onion" developed around heat storage well and heat recovery expectations have been made at the ETH, Zurich, Switzerland which suggest that a pilot experiment would provide valuable proof of the principle and indicate the scope of its applications. A much more serious constraint on brine pond usage is environmental . The concrete tank holding the pond survived the pressure of foot-thick ice without damage, but subsequent bulldozer operations near the tank undermined its footings. This provoked the thought that a serious leak in a large hypersaline pond could discharge brine into the vadose zone and eventually contaminate groundwater to such an extent that the water quality of wells in the vicinity would suffer for years. For this reason the present experiment has been terminated. Clearly, brine ponds should be built only in places where they do not impose an environmental threat, as in connection with marine aquaculture tank or polder heating where inadvertent salt leakage would be of no consequence. Theoretical and experimental study of the physics of brine pond efficiency indicates that the 20m2, 20-ton experiment just concluded, represents the lower limit of practical size. Theory suggests that a more nearly optimum pond would be about 10,000 m2 (one hectare) in area and 3 m deep with a much more gentle pycnocline developed in the upper 1 m. The pond should be quite fresh in the upper 20 cm and reach higher salt concentrations below the 1 m level. Since the coal layer tends to be neutrally buoyant at 40% brine concentrations it thus becomes involved in convection and shades the bottom layers. A lower salt concentration would prove advantageous in terms of heat collection and heat storage capabilities. Wave and wind-stirring action on a large pond would have to be suppressed, possibly by floating a grid of wooden booms on the surface. Large solar ponds are being studied at the Dead Sea Works in Israel. It would be very instructive to conduct similar experiments in the less favorable climate of New England.Prepared for the Department of Commerce, NOAA Office of Sea Grant under Grant #01-7-158-44104

Xylem embolism refilling and resilience against drought-induced mortality in woody plants: processes and trade-offs

Understanding which species are able to recover from drought, under what conditions, and the mechanistic processes involved, will facilitate predictions of plant mortality in response to global change. In response to drought, some species die because of embolism-induced hydraulic failure, whilst others are able to avoid mortality and recover, following rehydration. Several tree species have evolved strategies to avoid embolism, whereas others tolerate high embolism rates but can recover their hydraulic functioning upon drought relief. Here, we focus on structures and processes that might allow some plants to recover from drought stress via embolism reversal. We provide insights into how embolism repair may have evolved, anatomical and physiological features that facilitate this process, and describe possible trade-offs and related costs. Recent controversies on methods used for estimating embolism formation/repair are also discussed, providing some methodological suggestions. Although controversial, embolism repair processes are apparently based on the activity of phloem and ray/axial parenchyma. The mechanism is energetically demanding, and the costs to plants include metabolism and transport of soluble sugars, water and inorganic ions. We propose that embolism repair should be considered as a possible component of a \u2018hydraulic efficiency-safety\u2019 spectrum. We also advance a framework for vegetation models, describing how vulnerability curves may change in hydrodynamic model formulations for plants that recover from embolism

The GenTree Platform:growth traits and tree-level environmental data in 12 European forest tree species

Abstract Background: Progress in the field of evolutionary forest ecology has been hampered by the huge challenge of phenotyping trees across their ranges in their natural environments, and the limitation in high-resolution environmental information. Findings: The GenTree Platform contains phenotypic and environmental data from 4,959 trees from 12 ecologically and economically important European forest tree species: Abies alba Mill. (silver fir), Betula pendula Roth. (silver birch), Fagus sylvatica L. (European beech), Picea abies (L.) H. Karst (Norway spruce), Pinus cembra L. (Swiss stone pine), Pinus halepensis Mill. (Aleppo pine), Pinus nigra Arnold (European black pine), Pinus pinaster Aiton (maritime pine), Pinus sylvestris L. (Scots pine), Populus nigra L. (European black poplar), Taxus baccata L. (English yew), and Quercus petraea (Matt.) Liebl. (sessile oak). Phenotypic (height, diameter at breast height, crown size, bark thickness, biomass, straightness, forking, branch angle, fructification), regeneration, environmental in situ measurements (soil depth, vegetation cover, competition indices), and environmental modeling data extracted by using bilinear interpolation accounting for surrounding conditions of each tree (precipitation, temperature, insolation, drought indices) were obtained from trees in 194 sites covering the species’ geographic ranges and reflecting local environmental gradients. Conclusions: The GenTree Platform is a new resource for investigating ecological and evolutionary processes in forest trees. The coherent phenotyping and environmental characterization across 12 species in their European ranges allow for a wide range of analyses from forest ecologists, conservationists, and macro-ecologists. Also, the data here presented can be linked to the GenTree Dendroecological collection, the GenTree Leaf Trait collection, and the GenTree Genomic collection presented elsewhere, which together build the largest evolutionary forest ecology data collection available