摘要:

Excurrent jets of a set of model clams that are discharging into the near‐wall region of a turbulent boundary layer in a laboratory flume. These false‐color images were produced using planar laser‐induced fluorescence and represent 16‐s averages of dye concentration fields associated with the excurrent jets. Fluid that leaves the excurrent siphone is dyed to represent phytoplankton‐depleted fluid, whereas the clear ambient fluid represents phytoplanktonrich fluid. This particular sequence of images shows how the speed of the crossflow affects the food‐depleted (high dye concentration) boundary layer that develops over the bed of clams in two different ways—through its direct effect on the trajectories of the excurrent jets and through its effect on turbulent mixin

ISSN:0002-8606    

DOI:10.1029/EO072i021p00233-01

年代:1991

数据来源: WILEY

摘要:

Singer's comments appear to misinterpret, or miss the emphasis of, several points in our article.1) He infers that we advocate “raising energy taxes or … directly enforcing conservation.” There are no explicit statements thereof in our article. The main thrust of the criticized item was that the public should be more aware and have a greater spirit of cooperation. We do feel that it is desirable that the public be better informed—something to which the AGU can contribute—entirely aside from governmental compulsion, something which is not AGU's

ISSN:0002-8606    

DOI:10.1029/EO072i021p00234-04

年代:1991

数据来源: WILEY

摘要:

Hot spot volcanic chains are a fundamental feature of the Earth's crust, but their origins are still poorly understood [Okal and Batiza, 1987]. The Hawaiian‐Emperor volcanic chain, which dominates the topography of the central Pacific ocean floor, is the best developed and most intensely studied of the known hot spot tracks. It continues to be one of the world's most important field laboratories for the study of igneous processes, plate movements, mantle convection, structure, geochemical evolution, and the properties of the lithosphere.Despite continued effort, fundamental questions regarding the composition, structure, and evolution of Hawaiian volcanos and their magma sources remain unanswered. This is largely due to the fact that only lavas representing the late stages in the evolution of the volcanos can be sampled at the surface. Most of the internal structure of the volcanos and evidence of their growth history and geochemical evolution are hidden from view. The most deeply eroded volcanos are exposed only to depths of a kilometer or so, whereas the volcanos rise some 5–15 km above the old ocean floor [Moore, 19

ISSN:0002-8606    

DOI:10.1029/EO072i021p00236

年代:1991

数据来源: WILEY

摘要:

In the past, geochemical research in forested watersheds has focused on understanding the basic processes that occur in soils and rocks. Watershed geochemical processes, however, are greatly influenced by, and in turn, greatly influence, both organisms and biological process in soils, and hydrologic responses of catchments. To date, geochemical research has dealt principally with basic chemical processes in soils and rocks, and much less with questions concerning hydrologic routing through catchments and the effects such routing has on temporal variation in chemical composition of surface waters.Research on flow generation in catchments has focused on intensive field studies on plots, hillslope sections, and small catchments, with extension to larger scales necessarily involving the application of conceptual models that might (or might not) be valid. The acquisition of direct experimental evidence (for example, verifying flow generation mechanisms) on larger‐scale watersheds has always been problematic. Although geochemists understand that the explanation of some geochemical observations requires that flow pathways be explicitly identified, and hydrologists understand that flow generation can be better elucidated if the geochemical history of waters is known, critical integrated communication between the disciplines is often lacking. In turn, biologists require physical and geochemical information to interpret biological effects in watersheds, and hydrologists and geochemists need to be aware of the effects of biological processes on hydrochemical response of catchment

ISSN:0002-8606    

DOI:10.1029/90EO00184

年代:1991

数据来源: WILEY