Sources and extent of pollution

1979 ◽  
Vol 205 (1158) ◽  
pp. 5-15 ◽  
Keyword(s):  
Radioactive Waste ◽  
Polychlorinated Biphenyls ◽  
Chemical Reaction ◽  
Sulphur Dioxide ◽  
Scientific Understanding ◽  
Fluid Mixing ◽  
Residence Times ◽  
Naturally Occurring ◽  
Definition Of ◽  
Natural Cycles

Before the sources and extent of pollution can be identified a definition of pollutants has to be agreed. The degree of disruption of natural cycles in the global ecosystem in terms of residence times and assimilation capacities must be assessed as a prerequisite of any system of control. The sources of man-made and naturally occurring chemicals that fall into this definition can be categorized and these are presented for reference. Specific examples of these categories are discussed in detail, e. g. sulphur dioxide, polychlorinated biphenyls and radioactive waste. Their distribution and dilution in the environment are governed by fluid mixing mechanisms. These can be modelled to allow prediction of effects at specific points taking into account disappearance by decay, chemical reaction and deposition. Reappearance through pathways which involve accumulation and remobilization can only be predicted when a complete scientific understanding of the mechanism has been established.

scholarly journals Conceptual and Practical Issues in the Pharmacological Treatment of Brain Injury

1993 ◽  
Vol 4 (3) ◽  
pp. 227-237 ◽  
Author(s):  
Donald G. Stein ◽  
Marylou M. Glasier ◽  
Stuart W. Hoffman
Keyword(s):  
Central Nervous System ◽  
Brain Injury ◽  
Time Course ◽  
Chemical Activity ◽  
Behavioral Testing ◽  
Naturally Occurring ◽  
New Information ◽  
Definition Of ◽  
Injury And Repair ◽  
The Brain

It is only within the last ten years that research on treatment for central nervous system (CNS) recovery after injury has become more focused on the complexities involved in promoting recovery from brain injury when the CNS is viewed as an integrated and dynamic system. There have been major advances in research in recovery over the last decade, including new information on the mechanics and genetics of metabolism and chemical activity, the definition of excitotoxic effects and the discovery that the brain itself secretes complex proteins, peptides and hormones which are capable of directly stimulating the repair of damaged neurons or blocking some of the degenerative processes caused by the injury cascade. Many of these agents, plus other nontoxic naturally occurring substances, are being tested as treatment for brain injury. Further work is needed to determine appropriate combinations of treatments and optimum times of administration with respect to the time course of the CNS disorder. In order to understand the mechanisms that mediate traumatic brain injury and repair, there must be a merging of findings from neurochemical studies with data from intensive behavioral testing.

Laboratory Experiments of Mass Transfer in the London Clay

1988 ◽  
Vol 127 ◽  
Author(s):  
P. J. Bourke ◽  
D. Gilling ◽  
N. L. Jefferies ◽  
D. A. Lever ◽  
T. R. Lineham
Keyword(s):  
Mass Transfer ◽  
Porous Media ◽  
Radioactive Waste ◽  
Mass Transport ◽  
Mathematical Models ◽  
Laboratory Experiments ◽  
Naturally Occurring ◽  
Diffusion And Convection ◽  
Waste Repository ◽  
London Clay

ABSTRACTAqueous phase mass transfer through the rocks surrounding a radioactive waste repository will take place by diffusion and convection. This paper presents a comprehensive set of measurements of the mass transfer characteristics for a single, naturally occurring, clay. These data have been compared with the results predicted by mathematical models of mass transport in porous media, in order to build confidence in these models.

scholarly journals An Environmental Friendly Perspective of Microbial Degradation

2018 ◽  
Vol 3 (2) ◽  
Keyword(s):  
Heavy Metals ◽  
Polychlorinated Biphenyls ◽  
Microbial Degradation ◽  
Aromatic Hydrocarbons ◽  
Environmental Conditions ◽  
Cost Effective ◽  
Environmental Friendly ◽  
Naturally Occurring ◽  
Degradation Of Pollutants ◽  
Poly Aromatic Hydrocarbons

In the recent years attempt to find cost-effective and ecological ways to deal with noxious waste led mankind to focus on the use of microbes for the degradation of pollutants. These environmental friendly remediation methods employs the microbial naturally occurring catabolic capabilities to alter, vitiate or accrue a large number of pollutants including poly aromatic hydrocarbons, polychlorinated biphenyls, radio nuclides ,heavy metals etc. High-through put analyses of environmentally relevant microbes provides an insight of their major degradative pathways as well as their competence to acclimate to altering environmental conditions.

scholarly journals Mathematical Modeling of the Distribution of Natural 14C, 234U, and 238U in a Regional Ground-Water System

Radiocarbon ◽  
1983 ◽  
Vol 25 (2) ◽  
pp. 291-300 ◽  
Author(s):  
F J Pearson ◽  
C J Noronha ◽  
R W Andrews
Keyword(s):  
Ground Water ◽  
Nuclear Waste ◽  
Site Selection ◽  
Selection Process ◽  
Natural Radionuclides ◽  
Water System ◽  
Residence Times ◽  
Naturally Occurring ◽  
Hydrologic Data ◽  
Regional Hydrology

Increasing concern with nuclear waste isolation technology is leading to additional studies of naturally occurring isotopes in ground water. Such studies provide information on 1) the use of radionuclides to estimate ground-water travel times and/or residence times. This information can he an extremely useful adjunct to conventional hydrologic data in developing the understanding of regional hydrology needed in the site selection process, and 2) the use of natural radionuclides as analogues to the behavior of radionuclides of concern in nuclear waste.

Insensitive average residence times in generalized semi-Markov processes

1981 ◽  
Vol 13 (04) ◽  
pp. 720-735 ◽  
Author(s):  
A. D. Barbour ◽  
R. Schassberger
Keyword(s):  
Steady State ◽  
Markov Processes ◽  
Broad Class ◽  
Residence Times ◽  
Steady State Distribution ◽  
State Distribution ◽  
Lifetime Distributions ◽  
Definition Of ◽  
Semi Markov Processes ◽  
Networks Of Queues

For a broad class of stochastic processes, the generalized semi-Markov processes, conditions are known which imply that the steady state distribution of the process, when it exists, depends only on the means, and not the exact shapes, of certain lifetime distributions entering the definition of the process. It is shown in the present paper that this insensitivity extends to certain average and conditional average residence times. Particularly interesting applications can be found in the field of networks of queues.

scholarly journals Review of the Scientific Understanding of Radioactive Waste at the U.S. DOE Hanford Site

2018 ◽  
Vol 52 (2) ◽  
pp. 381-396 ◽  
Author(s):  
Reid A. Peterson ◽  
Edgar C. Buck ◽  
Jaehun Chun ◽  
Richard C. Daniel ◽  
Daniel L. Herting ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Scientific Understanding ◽  
Hanford Site ◽  
The U.S

Overview of the JAEA Knowledge Management System Supporting Implementation and Regulation of Geological Disposal in Japan

2009 ◽  
Author(s):  
Hiroyuki Umeki ◽  
Kazumasa Hioki ◽  
Hiroyasu Takase ◽  
Ian McKinley
Keyword(s):  
Knowledge Management ◽  
Radioactive Waste ◽  
Waste Management ◽  
Management System ◽  
Knowledge Management System ◽  
Radioactive Waste Management ◽  
Energy Agency ◽  
Geological Disposal ◽  
Definition Of ◽  
Site Characterisation

The exponential growth in the knowledge base for radioactive waste management is a cause for concern in many national programmes. In Japan, this problem is exacerbated by a volunteering approach to siting of a deep geological repository, which requires particular flexibility in the tailoring of site characterisation plans, repository concepts and associated performance assessments. Recognition of this situation led, in 2005, to initiation by Japan Atomic Energy Agency (JAEA) of an ambitious project to develop an advanced Knowledge Management System (KMS) aimed to facilitate its role as the supplier of background R&D support to both regulators and implementers of geological disposal. This overview outlines the boundary conditions and milestones for the Japanese radioactive waste management programmes, the roles of key organisations and the particular responsibilities of JAEA that led to definition of the goals of the KMS.

Investigations of the distribution of residence times of river impoundments using naturally occurring tracers

1983 ◽  
Vol 1 (1) ◽  
pp. 10-14
Author(s):  
R. Klopp ◽  
J. Sommer ◽  
K. H. Kornatzki ◽  
D. R. Albrecht
Keyword(s):  
Residence Times ◽  
Naturally Occurring
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