DAMMING JAMES BAY: I. POTENTIAL IMPACTS ON COASTAL CLIMATE AND THE WATER BALANCE

The proposed grand Canal project calls for the damming of James Bay and the diversion of its water southward. This first part of a two-part study models some potential impacts on the climate, water balance, and growth patterns in the James Bay coastal zone. Use is made of a linear relationship of Bowen ratio and temperature, developed from studies of coastal wetlands in southern and northwestern James Bay and central Hudson Bay. It is hypothesized that changing James Bay into a fresh-water lake and disrupting its coastal currents would result in a delayed Bay ice melt of unknown length in the spring. Allowing a delay to vary between 0 and 30 days results in the prediction of lesser evaporation and greater water surplus. These differences in magnitude increase with the length of delayed melt, but in all cases are most strongly evident during the peak of the growing season. Colder and wetter conditions would have a strong ecological impact on all coastal areas of western and southern James Bay. In the northwest this could change the species composition of coastal flora, cause forests to retreat from the coast, and result in the growth of permafrost there.     

MANAGEMENT OF THE WATER BALANCE OF THE ARAL SEA

In view of the declining inflow into the Aral Sea, alternative proposals are advanced to save this inland sea by reducing its area as well as its salinity levels. The proposals involve the closing off of some portions of the sea, notably the Little Aral in the northeast and the Western Aral, from the large shallow eastern portion. Some portions of this fragmented sea would then be treated as active bodies of water with a throughflow regime, discharging surplus waters of high salinity into other portions, which would be allowed to become salt marshes. Various combinations of active water areas and residual water areas are examined, and possible trends in waterlevel and salinity are projected to the middle of the 21st century.     

ON THE PROBLEM OF REGULATING THE REGIME OF THE CASPIAN SEA

In an effort to stabilize the declining level of the Caspian Sea, it has been proposed that evaporation from the water surface be reduced by decreasing the size of the sea through construction of a dam in the northern portion. Data on the geology and hydrology of the Caspian Sea bed suggest that the construction of a dam might have undesirable consequences not only for the northern fisheries basin but for the sea as a whole. The findings are based on the presence of salt domes on the bottom of the northern Caspian Sea. An influx of highly mineralized subsurface waters along faults associated with the salt domes as well as leaching of salt from the structures themselves may threaten to raise the salinity of the northern fisheries basin to intolerable magnitudes. The presence of a man-made dam, in the author's view, would also interfere with the natural circulation of water, threatening contamination of deeper layers of the Caspian Sea with hydrogen sulfide, as has happened in the case of the Black Sea. [For a discussion of the Caspian Sea problem, see Soviet Geography, November 1972.]     

A 6000 Year‐old Fossil Dugong from Botany Bay: Inferences about Changes in Sydney's Climate,Sea Levels and Waterways

The excavation in the 1890s of a skeleton of the warm‐water marine mammal Dugong dugon, associated with Aboriginal artefacts, from a Botany Bay salt marsh, marked the beginning of speculation about climate and sea level change in Australia over the period of human occupation. The dugong bones have recently been dated, giving a conventional ¹⁴C age of 5520±70 years BP, which is consistent with three older ¹⁴C dates for a layer of buried trees that underlies much of the north Botany sediments. The carefully drawn cross‐sections of depositional strata produced by the original discoverers allow further interpretation of the pattern of Holocene sea‐level fluctuations in the Sydney region. Layers of estuarine sediment, such as the one containing the dugong skeleton, are inter‐bedded with peat layers containing in situ roots and stumps, suggesting that the site alternated between sub‐aerial exposure and submergence throughout the Holocene. The presence of the dugong is suggestive of warmer conditions, and its inland location indicates a more extensive Botany Bay in the recent past. This is in agreement with other work from southern New South Wales describing both warm‐water marine species and higher sea levels several thousand years ago.

相似文献   

Spatial variations in the salinity of pore waters in northern deep water Gulf of Mexico sediments: implications for pathways and mechanisms of solute transport

Spatial variations in the salinity of pore waters in sedimentary basins can provide important insight into basin-scale hydrogeologic processes. Although there have been numerous studies of brine seeps in the deep water Gulf of Mexico, much less is known about porewater salinities in the vast areas between seeps. A study has been made of spatial variation in pore water salinities in sediments in an approximately 500 km by 200 km area of the northern deep water (water depth >500 m) Gulf of Mexico sedimentary basin (GOM) to provide insight into pathways and mechanisms of solute transport in this portion of the basin. A second objective was to document salinities in the upper 500 m of the sedimentary section, the approximate depth to which methane hydrates, a potential future energy resource, may be stable. Elevated salinities would reduce the P – T stability range of hydrates. Salinities were calculated from borehole logs using a dual electrical conductivity model. Even though much of the northern GOM is underlain by allochthonous salt most of the undisturbed shallow sedimentary section has not been permeated by hypersaline waters. These waters are limited to areas near brine seeps. Hypersaline waters having salinities in excess of 100 g l⁻¹ become more common at subseafloor depths of 2 km and greater. A field study at Green Canyon 65 and published numerical simulations of fluid flow above tabular salt bodies suggest that brines produced by salt dissolution migrate laterally and pond above salt and/or within minibasins and that the dominant mechanism of vertical solute transport is a combination of compaction-driven advection and diffusion, not large-scale thermohaline overturn. Superimposed on this diffuse upward flux of dissolved salt is the more focused and localized expulsion of saline fluids up faults.     

Diverse origins and timing of formation of basinal brines in the Gulf of Mexico sedimentary basin

A review of five different field areas in the Gulf of Mexico sedimentary basin (GOM) illustrates some of the potentially diverse chemical and physical processes which have produced basinal brines. The elevated salinities of most of the formation waters in the GOM are ultimately related to the presence of the Middle Jurassic Louann Salt. Some of these brines likely inherited their salinity from evaporated Mesozoic seawater, while other saline fluids have been produced by subsequent dissolution of salt, some of which is occurring today. The timing of the generation of brines has thus not been restricted to the Middle Jurassic. The mechanisms of solute transport that have introduced brines throughout much of the sedimentary section of the GOM are not entirely understood. Free convection driven by spatial variations in formation water temperature and salinity is undoubtedly occurring around some salt structures. However, the driving mechanisms for the broad, diffusive upward solute transport in the northern Gulf rim of Arkansas and northern Louisiana are not known. In the Lower Cretaceous of Texas, fluid flow was much more highly focused, and perhaps episodic. It is clear that many areas of the Gulf basin are hydrologically connected and that large‐scale fluid flow, solute transport, and dispersion have occurred. The Na‐Mg‐Ca‐Cl compositions of brines in the areas of the Gulf Coast sedimentary basin reviewed in this article are products of diagenesis and do not reflect the composition of the evaporated marine waters present at the time of sediment deposition. Large differences in Na, Ca, and Mg trends for waters hosted by Mesozoic versus Cenozoic sediments may reflect differences in: (i) the sources of salinity (evaporated seawater for some of the Mesozoic sediments, dissolution of salt for some of the Cenozoic sediments); (ii) sediment lithology (dominantly carbonates for much of the Mesozoic sediments, and dominantly siliciclastics for the Cenozoic sediments); or (iii) residence times of brines associated with these sediments (tens of millions of years versus perhaps days).     

Detection of chloride from pottery as a marker for salt: A new analytical method validated using simulated salt-making pottery and applied to Japanese ceramics

Salt is an essential mineral in the human diet, and ancient peoples obtained salt either directly from rock salt, from salt lakes, or by concentrating saline waters from salt springs or seawater in pottery vessels. However, because sodium chloride, the major component of salt, is soluble in water, it has been thought unlikely that any trace of salt would remain in the pottery after a long period of time. A new methodology for retrieval of water-insoluble (retainable) chloride ion trapped within a pottery matrix is presented as a method for detecting previous use of the pottery for salt making. Simulated salt-making pottery was used to make salt by repeatedly boiling seawater over a fire. After chloride had been extracted with distilled water, to mimic the removal of chloride by natural waters such as rainwater and groundwater, an aqueous ammonium fluoride solution was shown to be capable of extracting chloride ions remaining in the pottery. A chloride-selective electrode was used to quantify the amount of extracted chloride in the presence of fluoride. This method was then successfully applied to excavated Japanese pottery vessels suspected of having been used for making salt. Identification of retainable chloride in pottery can offer insights into salt trading networks, which reflect the growth and affluence of an ancient society.     

THE MORPHOMETRY OF THE CASPIAN SEA BASED ON CONTEMPORARY DATA

Differences in available data on the area of the Caspian Sea are analyzed, and an effort is made to explain them. The differences are particularly pronounced in the shallower northern portion of the sea, where the drop of the sea level over the years has produced more significant changes in shoreline configuration. Greater use of space imagery is urged in determining changes in shoreline configuration, and the setting of “geographical standards” is proposed to avoid continuing confusion in published data. The technical problem of calculating the physical water area, including surface roughness produced by wave motion, is discussed.     

新中国区际粮食流通的三次变化及其原因分析

新中国50多年间,粮食流通经历了计划调拨到市场调节的变化过程。在这一变化过程中,粮食流向流量发生了由南粮北调到北粮南运到北出南进乃至南北同出三次历史性变化。通过对这一过程和相关因素的分析可以看出,这三次重大的历史变化既是中国区域经济在市场化主导下非均衡发展的结果,同时,它又将对区域经济和国民经济、世界经济的进一步发展和调整产生重大的影响。     

High modernism in the Arctic: planning Frobisher Bay and Inuvik

This paper considers Frobisher Bay and Inuvik, two Canadian Arctic towns, as examples of the high-modernist planning that swept the globe during the middle decades of the twentieth century, but also Cold War projects reflecting a sudden interest in the Arctic as a region of military significance. Building on the framework provided by James Scott in Seeing like a State (1998), the paper details the connections between modernization theory and Cold War militarism before turning to the strikingly parallel case studies. In each instance, federal officials proposed ambitious urban models designed to simultaneously overcome the hostility of a northern environment and catapult native northerners into conditions of modern living. While the limits and failings of such schemes varied by location, both sites were also laboratories for social scientists employed by the federal government to document and analyze the modernization of the Arctic. The work of these scholars represents a particularly rich and complex record of governmental interventions, tied variously to Cold War imperatives, in northern lives and landscapes at a time of great faith in the transformative power of modern engineering.     

Indications of formation water flow and compartmentalization on the flank of a salt structure derived from salinity and seismic data

Vertical and lateral variations in lithology, salinity, temperature, and pressure determined from wireline LAS logs, produced water samples, and seismic data on the south flank of a salt structure on the continental shelf, offshore Louisiana indicate three hydrogeologic zones in the study area: a shallow region from 0 to 1.1 km depth with hydrostatically pressured, shale‐dominated Pleistocene age sediments containing pore waters with sea water (35 g l^?1) or slightly above sea water salinity; a middle region from 1.1 to 3.2 km depth with near hydrostatically pressured, sand‐dominated Pliocene age sediments that contain pore waters that range from seawater salinity to up to 5 times sea water salinity (180 g l^?1); and a deep section below 3.2 km depth with geopressured, shale‐dominated Miocene age sediments containing pore waters that range from sea water salinity to 125 g l^?1. Salt dissolution has generated dense, saline waters that appear to be migrating down dip preferentially through the thick Pliocene sandy section. Sand layers that come in contact with salt contain pore waters with high salinity. Isolated sands have near sea water salinity. Salinity information in conjunction with seismic data is used to infer fluid compartmentalization. Both vertical and lateral lithologic barriers to fluid flow at tens to hundreds of meters scale are observed. Fluid compartmentalization is also evident across a supradomal normal fault. Offset of salinity contours are consistent with the throw of the fault, which suggests that saline fluids migrated before fault formation.     

良渚玉器部分玉料来源的蠡测

良渚文化玉器中,有一种玉器的玉质细腻纯净,透明度较高,颜色为黄绿和深浅不一的绿色。这类玉料的外观与江浙一带所产玉料截然不同,而与辽东半岛岫岩所产软玉极为相似。因此,良渚玉器部分玉料可能采源于辽东半岛。岫岩软玉的传输路线,是从辽东半岛南部沿海出发,渡过渤海海峡到达胶东半岛,再向西南入山东腹地,折向南到江苏北部进入良渚文化分布区。在这条玉材传送路线上起运输中转作用的,是辽东半岛的原始部落和以大汶口、龙山文化为代表的山东地区原始部落。     

可溶盐NaCl和CaCl2对陶质文物的酥粉作用

研究可溶盐NaCl和CaCl_2复合盐破坏陶质文物过程中作用本质,在复合盐溶液的平衡结晶相分析基础上,分析陶质样品中可溶盐溶液的吸收和水分蒸发速率变化,以及采用超景深显微系统、扫描电子显微系统等检测可溶盐NaCl、CaCl_2和复合盐溶液对陶质样品的破坏过程和作用。结果表明:陶质样品破坏的本质在于可溶盐结晶受力过程中微裂纹的扩展和贯通,在环境相对湿度变化引起裂纹扩展贯通过程中,陶质样品表面逐层粉化脱落,质量、形貌和强度都发生着一定程度的改变,其中NaCl结晶体对陶质样品产生的作用力较大,破坏性最强,而NaCl溶液中加入的CaCl_2延长了盐结晶所需要的时间,间接地阻碍了NaCl的结晶析出,反而对陶质样品起到了一定的保护作用。研究结果为进一步酥粉陶质文物的保护研究提供科学依据。     

GPS satellite measurements: ionospheric slab thickness and total electron content

A preliminary analysis was made of ionospheric slab thickness, τ, and total electron content, TEC, for southern Australia using GPS satellite measurements. It was found that at mid-latitudes τ has similar overall diurnal, seasonal and latitudinal variations in the southern hemisphere as in the northern hemisphere. However, there are appreciable differences between τ in the two hemispheres which would justify appropriate modifications to ionospheric models based on northern hemisphere data before being applied confidently to the southern hemisphere. The usefulness of GPS satellites together with ionosondes over a spread of latitudes was demonstrated in determining long-term variations of TEC and τ over a large area. It was concluded that as few as four GPS receivers could provide TEC for the whole of Australia in real-time, though approximately six receivers in convenient locations would be required in practice.     

Keeping Pace With Rising Sea: The First 6 Years of the Lower Suwannee Archaeological Survey,Gulf Coastal Florida

Low-gradient coastlines are susceptible to inundation by rising water, but they also promote marsh aggradation that has the potential to keep pace with sea-level rise. Synergies among hydrodynamics, coastal geomorphology, and marsh ecology preclude a simple linear relationship between higher water and shoreline transgression. As an archive of human use of low-gradient coastlines, archaeological data introduce additional mitigating factors, such as landscape alteration, resource extraction, and the cultural value of place. The Lower Suwannee Archaeological Survey (LSAS) is an ongoing effort to document the history of coastal dwelling since the mid-Holocene, when the rate and magnitude of sea-level rise diminished and the northern Gulf coast of Florida transitioned into an aggradational regime. Results of the first 6 years of the LSAS suggest that multicentury periods of relative stability were punctuated by site abandonment and relocation. Subsistence economies involving the exploitation of oyster and fish, however, were largely unaffected as communities redistributed themselves with changes in shoreline position and estuarine ecology. After AD 200, civic-ceremonial centers were established at several locations along the northern Gulf coast, fixing in place not only the infrastructure of daily living (villages), but also that of religious practice, notably cemeteries and ceremonial mounds. Intensified use of coastal resources at this time can be traced to a ritual economy involving large gatherings of people, terraforming, feasting, and the circulation of socially valued goods. To the extent that religious practices buffered the risks of coastal living, large civic-ceremonial centers, like aggrading marshes, afforded opportunities to “outpace” sea-level rise. On the other hand, centers introduced a permanence to coastal land-use that proved unsustainable in the long term.     

元和明前期南北差异的博弈与整合发展

元朝统一后,南方与北方差异依然存在,导致国家制度层面亦呈现南、北因素的并存博弈。由于元政权北制因素势力过分强大,北方制度向江南的推广移植明显多于南制因素的保留及北上影响,初次博弈整合的结果,北制因素稳居上风。元明鼎革,承袭元朝制度颇多,朱元璋、朱棣的个人因素与社会关系等力量的交互作用,致使明前期南、北制因素的那次整合仍然是北制多占优势。明中叶后又实施另一次整合,且改为南制占主导。先后经历元朝、明前期以北制为主导和明中叶后南制为主导的三次整合,明后期才重新回归到代表唐宋变革成果的南制方面且得以升华发展。此乃元明二代因南、北差异而展现的社会整合发展的基本脉络和走势。就社会形态的核心——社会关系而言,主从隶属依附,大抵是北制的要害;租佃雇佣,大抵是南制的真谛。     

PRINCIPAL TRENDS AND PROSPECTS OF THE USE OF WATER RESOURCES IN THE USSR

The increasing demand on water in the Soviet Union and the problem of assuring water quality require the construction of long-term water-management balances by drainage basins. These balances, based on predicted demand and water availability, would suggest the need for water-management projects within basins and interbasin transfers. Water needs would be evaluated both in terms of water requirements by categories of users and in terms of water quality. The most crucial regional problems involve the increasing shortage of water in Central Asia (with the prospect of interbasin transfer from Siberia) and in southern regions of the European USSR (with the problem of diverting water southward from the northern runoff slope). The Caspian Sea is expected to require a supplementary inflow of 80 to 100 cubic kilometers a year by the end of the century if the decline of its waterlevel is to be arrested. But southward diversion of northern waters is not expected to add more than 50 to 70 km³ at best, with a possible saving of an additional 10 to 20 km³ through decline of evaporation from a reduced Caspian Sea surface. The preservation of conditions in the Sea of Azov, the Aral Sea and Lake Balkhash pose additional water problems. [The senior author died in October, 1974].     

ON THE INADVISABILITY OF THE PROJECTED DAM ACROSS KERCH' STRAIT

The proposed dam across the Kerch' Strait is opposed both on econonic grounds and because it is unlikely to achieve its basic purpose of reducing the salinity level in the Sea of Azov and restoring earlier fish productivity. Calculations are presented to show that the additional streamflow into the Sea of Azov needed to reduce salinity from the present 15 per thousand to 10 per thousand would be far more costly than the revenue that could be derived from fisheries. It is proposed that the loss in fish productivity in the Sea of Azov might be compensated for far more economically by developing pond fisheries in the drainage basin and by introducing brackish-water and marine species into the sea.     

BASIC PRINCIPLES FOR A CONCEPTUAL FRAMEWORK OF DEVELOPMENT AND LOCATION OF PRODUCTIVE FORCES IN THE NONCHERNOZEM ZONE OF THE RSFSR

A development strategy is proposed for the Nonchernozem zone of the European RSFSR, which is now the object of a major program of rural modernization (see S.G., March, April 1975). The principal factors affecting future strategy are geographical situation and physical setting, resource potential, level of economic development and settlement, availability of skilled labor and technical progress. The proposed strategy calls for focusing northern development on resource exploitation, fostering manufacturing development in the central oblasts outside the major industrial nodes, where industrial expansion should be restricted, and limiting industrial construction in the southern grain-growing oblasts to avoid diverting valuable agricultural land to nonfarm uses. The Nonchernozem zone will continue to be the nation's research and development center and aim at economic growth through intensive methods in view of a labor shortage.     

THE RIVER HAS NEVER DIVIDED US: BRONZE AGE METALWORK DEPOSITION IN WESTERN BRITAIN

The significant quantities of Bronze Age metalwork recovered from the River Thames have focused archaeological attention on the presence of metalwork from riverine locations and led to the expectation that rivers should contain metalwork. Finds from bogs and marshes have also been considered to be part of this practice of deposition in ‘wet places’. Whilst rivers and bogs can indeed be thought of as ‘wet’, this overlooks the fundamental physical and cosmological differences between these two types of wetland. This paper will consider Bronze Age metalwork finds from rivers in the west of Britain, paying particular attention to Britain's longest river, the Severn. The finds will be compared to those from bogs and marshes, and an attempt will be made to explain these differences in terms of the opposing metaphorical qualities of flowing and standing water, and the landscapes in which these wet places are located.