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[en] The concentration of dissolved uranium has been determined in over 250 river waters from the Orinoco, Amazon, and Ganges basins. Uranium concentrations are largely determined by dissolution of limestones, although weathering of black shales represents an important additional source in some basins. In shield terrains the level of dissolved U is transport limited. Data from the Amazon indicate that floodplains do not represent a significant source of U in river waters. In addition, the authors have determined dissolved U levels in forty rivers from around the world and coupled these data with previous measurements to obtain an estimate for the global flux of dissolved U to the oceans. The average concentration of U in river waters is 1.3 nmol/kg, but this value is biased by very high levels observed in the Ganges-Brahmaputra and Yellow rivers. When these river systems are excluded from the budget, the global average falls to 0.78 nmol/kg. The global riverine U flux lies in the range of 3-6 x 107 mol/yr. The major uncertainty that restricts the accuracy of this estimate (and that of all other dissolved riverine fluxes) is the difficulty in obtaining representative samples from rivers which show large seasonal and annual variations in runoff and dissolved load
[en] After an introductory part concerned with general requirements and properties of models, model calculation dealing with the dispersion of radioactive substances in the Austrian part of the Danube River are shown. The chosen model is a deterministic one which takes into account dilution, dacay and retention. Key parameters are identified for some radiological important radionuclides. (Author)
[en] The radial sand ridge system (RSRS) located at Jiangsu coast of China attracts much attention on its origin and mechanic of formation for its special structure and potential land resource. Due to complicated hydrodynamic condition, the Jiangsu RSRS is a hot debated on its potential sources, Yangtze River or Yellow River? We collected ten sand samples from surface sediments along the west coast of Bohai Sea and Yellow Sea from the modern Yellow River estuary to Yangtze River estuary in summer, 2013. The samples are analyzed by method of detrital zircon age for source identification of the RSRS sediments. The U-Pb age spectra of detrital zircon grains of the samples show a wide range from Cenozoic to Late Archean with several age peaks. Comparing the age spectra between the Yangtze River and the Yellow River, the detrital zircons have younger age (<100 Ma) group in the Yangtze River. These age distribution of the Jiangsu coastal RSRS sediments are similar to that of the Yangtze River, but different from the Yellow River. The samples located adjacent to the old Yellow River Delta show more wide-range age distribution, implying a compounded origination from the both rivers. Based on these findings it is proposed that, contrary to common opinion, the main sediment source of the Jiangsu RSRS is the Yangtze River, rather than the Yellow River. By implication, there should be evidence of hydrodynamic mechanics of oceanic currents and tidal motion. This aspect awaits confirmation in future research.
[en] A deterministic model was used for predicting the activity concentration of radionuclides in rivers. The model was validated in the framework of VAMP, aquatic working group, river subgroup, where scenarios as Clinch-Tennessee rivers as well as Dnjepr river were provided. This was a good chance to test the predictive power of the model. Some of the results of this exercise are presented. (author)
[en] The purpose of this report is to present, in the light of the information and experience accumulated to date, those principles and practices which, if applied to the disposal of radioactive wastes into inland surface and estuarial waters will ensure that man will not experience radiation exposures that are above the limits recommended by the International Commission for Radiation Protection (ICRP); and further, that radiation exposures are kept as far below those limits as is practicable. Disposal into sub-surface waters has not been specifically considered as this topic has been covered in another International Atomic Energy Agency publication. The report discusses the mechanisms and parameters which affect and control the fate of radionuclides introduced into fresh waters; it discusses the concepts of ''critical nuclide'', ''critical pathway'' and ''critical population group'' and demonstrates how the use of these concepts provides a sound, convenient and economical means for setting discharge limits and maintaining a continuing surveillance. It offers practical advice on the use of these concepts; gives some detailed information on uptake and dispersion mechanisms; and offers instruction on how to use this information and these concepts to estimate potential radiation doses and thus establish discharge limits.
[en] In 1994, the Nez Perce Tribe began a smolt monitoring study on the Imnaha River in cooperation with the Fish Passage Center (FPC). A rotary screw trap was used to collect emigrating wild and hatchery chinook salmon (Oncorhynchus tshawytscha) and steelhead trout (Oncorhynchus mykiss) smolts from March 1 to June 15, 1994. We PIT tagged and released 956 wild chinook salmon, 661 hatchery chinook salmon, 1,432 wild steelhead trout and 2,029 hatchery steelhead trout. Cumulative interrogation rates at mainstem Snake and Columbia River dams were 62.2% for wild chinook salmon, 45.2% for hatchery chinook salmon, 51.3% for wild steelhead trout, and 34.3% for hatchery steelhead trout
[en] To clarify the current situation of haze emission and governance in China, the study analyzed the characteristics of spatial correlation structure and synergistic governance development of the haze emission of 31 provinces in China, based on social network analysis and distance synergistic model. The results indicated that the spatial correlation of inter-provincial haze emission in China presented a typical “central–marginal” network structure. The provinces in the network center were mostly located in the Beijing–Tianjin–Hebei region and the Yangtze River Delta region. The synergistic governance development of haze in China showed a lower level and fluctuating upward trend. In addition, the increase of network density, the decline of network grade, and the decrease of network efficiency would all improve the level of synergistic governance development. Therefore, focusing on the haze of the central provinces, improving the network structure, and improving regional synergy are important measures for effective governance. This paper improves the previous research model, considers the impact of economic and demographic factors on haze pollution, establishes a new model for analyzing spatial correlation structure of haze and calculating the synergistic governance level of haze, and designs feasible ways to raise the synergistic governance level of haze in China.
[en] The 1994 Fish and Wildlife Program of the Northwest Power Planning Council specifies the recovery and preservation of population health of native resident fishes of the Columbia River Basin. Among the native resident species of concern are interior rainbow trout of the Columbia River redband subspecies Oncorhynchus mykiss gairdneri 1 and westslope cutthroat trout O. clarki lewisi. The westslope cutthroat trout has been petitioned for listing under the U. S. Endangered Species Act (American Wildlands et al. 1997). Before at-risk populations can be protected, their presence and status must be established. Where introgression from introduced species is a concern, as in the case of both westslope cutthroat trout and redband rainbow trout, genetic issues must be addressed as well. As is true with native trout elsewhere in the western United States (Behnke 1992), most of the remaining pure populations of these species in the Columbia River Basin are in relatively remote headwater reaches. The objective of this project is to photo-document upper Columbia Basin native resident trout populations in Washington, and to ascertain their species or subspecies identity and relative genetic purity using a nonlethal DNA technique. FY-99 was year two of a five-year project in which we conducted field visits to remote locations to seek out and catalog these populations. In FY-99 we worked in collaboration with the Colville National Forest and Kalispel Indian Tribe to catalog populations in the northeastern corner of Washington State
[en] To provide information for the development of management strategies to reduce N loads and enhance N attenuation mechanisms, isotopic techniques have been used to investigate the sources and cycling of nutrients at a number of sites in the Mississippi Basin (which includes the Ohio and Missouri River Basins). About half of the POM in the Mississippi (and other big rivers in the USA) is composed of plankton and/or heterotrophic bacteria. This suggests that in-situ productivity may be a significant source of bioavailable organic matter contributing to the hypoxia in the Gulf of Mexico. Monthly samples from 19 river sites in the Basin sampled over 5 years showed that δ 15N and δ 13C were quite useful in discriminating among four major categories of POM: terrestrial soil, fresh terrestrial vegetation, aquatic macrophytes, and plankton/bacteria The isotopic data, along with ancillary chemical and hydrologic measurements, were also useful for documenting seasonal changes in in-situ processes. A pilot study in 2000-2001, designed to investigate the usefulness of isotopic techniques for determining nutrient sources in 24 medium and large watersheds in the Basin, found that nitrate and POM from basins with different land uses (e.g., row crops, animal farming, urban development, and undeveloped) had moderately distinctive isotopic compositions. The nitrate δ 18O and δ 15N values of the large rivers sites resembled the compositions seen in sites dominated by row crops. Sites with livestock tended to have high δ 15N values characteristic of manure, and urban and undeveloped sites tended to have higher δ 18O values characteristic of a significant fraction of atmospheric nitrate. The δ 18O data were critical in showing abrupt changes in nitrate sources with discharge. A more thorough study of nutrient sources in the Ohio River Basin was initiated in 2002. For this study, nitrate, POM, and water were collected 15-20 times each year at 6 small NAWQA-program watersheds in the White River- Miami River basins, and at the 7 large river NASQAN-program sites in the Ohio River Basin. Nitrate samples were analyzed for δ 15N and δ 18O, POM for δ 15N and δ 13C, and water for δ 18O and δ 2H. The δ 15N and δ 13C of fish were used as indicators of nutrient sources. Other studies have indicated that POM consists primarily of phytoplankton and is transported in the water column, particularly size fractions < 1-mm diameter, were the primary food source for food webs in the Ohio and Upper Mississippi Rivers
[en] This book is about water quality and other characteristics of selected ecosystems in North America. It is also about changes that have occurred in these ecosystems as a result of recent human activities-changes that result primarily from development and exploitation to sustain the needs of an ever-increasing population and the technical innovations that sustain it. Fish populations, hydrology, and water quality control efforts are discussed