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41.
Examination of the consequences of the stoichiometric association constant K1a = 41.7 for MgSO4 in seawater as advocated by Johnson and Pytkowicz (1979) leads to a thermodynamic association constant Ka = 212.6, a value 32% greater than KA = 160 derived from conductance data. Use of Ka = 160 leads to a K1a in essential agreement with the value of 10.2 reported by Kester and Pytkowicz (1969).  相似文献   
42.
The diversity of manufacturing in the United States South has shown a substantial increase during the post-World War II period. The basis for this changing industrial structure is found in the expansion of food processing and apparel industries but particularly since 1967 in a variety of higher-pay and higher-technology industries. The traditional textile states remain the least diversified and the slowest to change.  相似文献   
43.
An H solar prominence with the characteristics of a spray was ejected in association with a bright limb flare. Knots of material were observed to a distance of more than one solar radius above the west limb of the Sun. The optical event was followed by 80 MHz emission from a type IV source which was observed moving out through several solar radii.Coronagraph observations have been used to determine the trajectories and velocities of the knots in directions perpendicular to the line of sight. After some early deceleration velocities increase to 300–500 km/sec and slowly decline with variations depending on the initial direction of outflow. We suggest that the magnetic field over the spot group is deformed by the energy of the mass motions of material fragments, some of which then continue to move outward from the Sun.  相似文献   
44.
An isophotal map of a small coronal loop, obtained from a coronagraph observation through a solid Fabry-Perot interferometer, is used to estimate the variation of emission per unit volume and the pressure gradient at the top and sides of the loop. The magnitude of the magnetic field necessary to maintain the estimated pressure gradients is found to be ¦H 2¦ = 30 G2.  相似文献   
45.
The evolution of the early Great Lakes was driven by changing ice sheet geometry, meltwater influx, variable climate, and isostatic rebound. Unfortunately none of these factors are fully understood. Sediment cores from Fenton Lake and other sites in the Lake Superior basin have been used to document constantly falling water levels in glacial Lake Minong between 9,000 and 10,600 cal (8.1–9.5 ka) BP. Over three meters of previously unrecovered sediment from Fenton Lake detail a more complex lake level history than formerly realized, and consists of an early regression, transgression, and final regression. The initial regression is documented by a transition from gray, clayey silt to black sapropelic silt. The transgression is recorded by an abrupt return to gray sand and silt, and dates between 9,000 and 9,500 cal (8.1–8.6 ka) BP. The transgression could be the result of increased discharge from Lake Agassiz overflow or the Laurentide Ice Sheet, and hydraulic damming at the Lake Minong outlet. Alternatively ice advance in northern Ontario may have blocked an unrecognized low level northern outlet to glacial Lake Ojibway, which switched Lake Minong overflow back to the Lake Huron basin and raised lake levels. Multiple sites in the Lake Huron and Michigan basins suggest increased meltwater discharges occurred around the time of the transgression in Lake Minong, suggesting a possible linkage. The final regression in Fenton Lake is documented by a return to black sapropelic silt, which coincides with varve cessation in the Superior basin when Lake Agassiz overflow and glacial meltwater was diverted to glacial Lake Ojibway in northern Ontario.  相似文献   
46.
Huiqun Wang  Jenny A. Fisher 《Icarus》2009,204(1):103-113
The complete archive of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) Mars Daily Global Maps (MDGM) are used to study north polar clouds and dust storms that exhibit frontal structures during the spring and summer (Ls 0-180°). Results show that frontal events generally follow the edge of the polar cap during spring and mid/late summer with a gap in the distribution in early summer. The exact duration and timing of the gap vary from year to year. Ten to twenty percent of spring and summer time frontal events exhibit complex morphologies. Distinct temperature signatures are associated with features observed in images in many but not all cases. The general travel paths of the frontal events are eastward around the polar cap. Westward paths exist only at the edge of the polar cap in late spring/early summer. Occasionally, the paths curve toward or away from the polar cap in certain longitude sectors.  相似文献   
47.
The availability of vector-magnetogram sequences with sufficient accuracy and cadence to estimate the temporal derivative of the magnetic field allows us to use Faraday’s law to find an approximate solution for the electric field in the photosphere, using a Poloidal–Toroidal Decomposition (PTD) of the magnetic field and its partial time derivative. Without additional information, however, the electric field found from this technique is under-determined – Faraday’s law provides no information about the electric field that can be derived from the gradient of a scalar potential. Here, we show how additional information in the form of line-of-sight Doppler-flow measurements, and motions transverse to the line-of-sight determined with ad-hoc methods such as local correlation tracking, can be combined with the PTD solutions to provide much more accurate solutions for the solar electric field, and therefore the Poynting flux of electromagnetic energy in the solar photosphere. Reliable, accurate maps of the Poynting flux are essential for quantitative studies of the buildup of magnetic energy before flares and coronal mass ejections.  相似文献   
48.
Abstract

Given the linkages between natural resources and social conflicts, evidence increasingly shows that successful natural resource management requires conflict mitigation and prevention. However, there may be a gap in practice between knowing what processes and tools need to be used to manage conservation conflicts and how to actually implement them. We present learning from a practice-based case study of conflict management in the Amarakaeri Communal Reserve in the Peruvian Amazon that aimed to develop natural resource governance institutions and build stakeholder capacity, including of indigenous groups, to navigate existing conflict resolution mechanisms. Through applying good practices in conservation conflict management and collaborative governance, we generated important lessons on the practical considerations involved in collaborative conservation. These lessons, while specific to our case, could be applied to a variety of protected areas facing complex social-ecological systems dynamics and wicked problems.  相似文献   
49.
Correctly estimating the effect of elevated CO2 (eCO2) on biomass production is paramount for accurately projecting agricultural productivity, global carbon balances and climate changes. Plant physiology suggests that eCO2 should result in a strongly positive CO2 fertilisation effect (CFE) via positive effects on photosynthesis and water use efficiency. However, the CFE in CO2 experiments is often constrained because of other factors of which rainfall pattern is particularly important. Here, we apply a generally applicable, empirically derived relationship between the CFE and an index of seasonal rainfall balance (SRB), to identify how historical and projected future rainfall patterns modify the CFE using 25 native grassland sites in south-eastern (SE) Australia as a test case. We found that historical and projected rainfall produced SRBs that varied widely from year-to-year resulting in a CFE that was only positive in about 40% of years, with no or even negative biomass responses in the remainder of years; a finding that is in marked contrast to other studies that have not taken account of relationships between rainfall seasonality and plant responses to CO2. The dependence of the CFE on SRB also means that using the CFE from a specific eCO2 experiment can be misleading as the result will be heavily influenced by the SRB during the period of experimentation but this problem can be avoided by using a robust general relationship of the kind used in this study. Generalisations of grassland biomass responses to the rising CO2 concentration are contextual in terms of the variability in precipitation seasonality; as such, this provides a new lens by which to view aboveground responses to the rising CO2 concentration and fosters a novel approach for cross-site comparisons among experiments.  相似文献   
50.
Long-term and seasonal geomorphological changes at Padre Island, Texas are identified and linked with potential external drivers. Aerial and satellite images from 1950 to 2018, monthly images from 2019 to 2020, and a 2018 LiDAR data set are used to assess long-term and seasonal geomorphological changes within a 50 km2 area of Padre Island near Port Mansfield, Texas. Trends in landcover are evaluated by mapping and comparing the relative areal coverage of each facies. Vegetated dunes, absent initially, emerged in the fore-island and expanded into the back-barrier to cover 14% of the study area. The active vegetation-free back-barrier dune field steadily decreased in areal extent from 12% to 6% as vegetation spread. Nebkha dune coverage fluctuated between 4% and 7%. Expansive microbial mats colonized the wind tidal and deflation flats surrounding the vegetated dunes and back-barrier dune field giving rise to a remarkably different landscape over the 50-year period studied. An assessment of external forcing factors identifies increased rates of relative sea level rise and decreased sediment influx as the most likely primary factors driving the geomorphological changes. These changes have induced a widespread shift toward stabilization of island sediments by vegetation and microbial mats, which in turn has starved the back-barrier of sediments resulting in low rates of accretion and increased flooding. These findings highlight the sensitivity of the back-barrier and, in particular, the dune facies to changes in sea level and sediment supply, and show that microbial mats are effective at stabilizing island sediments and may be harbingers to barrier island response to rising sea level. As shown in this study, long-term monitoring of geomorphic facies changes and topography can detect important shifts in the island state that can be used to inform decision making for these sensitive coastal landscapes.  相似文献   
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