Alteration of basaltic glass: Mechanisms and significance for the oceanic crust-seawater budget

Alteration of basaltic glass to palagonite is characterized by a nearly isomolar exchange of SiO₂, Al₂O₃, MnO, MgO, CaO, Na₂O, P₂O₅, Zn, Cu, Ni, Cr, Hf, Sc, Co and REE for H₂O and K₂O, whilst TiO₂ and FeO are passively accumulated during removal of the remaining cations. The network forming cations Al and Si are removed from the glass in proportion to the gain in Ti and Fe, whilst the other cations do not show a significant relationship to the amount of Ti and Fe accumulation. Sr isotopic data show that during palagonite formation approximately 85% of the basaltic Sr is lost to the hydrous solutions and 40% of seawater Sr is added to the glass, yielding an average loss of the same order of magnitude as of the network forming cations. Losses and gains of oxides yield an average increase of +105% TiO₂.K, Rb, and Cs show high increases, but $\text{K}\text{Rb}$ and $\text{K}\text{Cs}$ ratios indicate two different alteration processes: (1) formation of palagonite involves a drastic decrease in these ratios, indicating structural similarities between palagonite and smectite; (2) surface alteration of glass is characterized by an increase in $\text{K}\text{Rb}$ and $\text{K}\text{Cs}$ ratios, probably best interpreted as sorption of alkalies in ratios approximating those of seawater.The total fluxes involved in alteration of glass in the upper portion of the oceanic crust are estimated from the modal abundance of palagonite in the oceanic crust and the abundance of the vein materials smectite and carbonate. Smectite and carbonates act as a sink for a significant portion of the elements liberated up during alteration of basaltic glass except for Na and Al, which are probably taken up by zeolites and/or albite, possibly hidden in the macroscopic estimate of carbonate. Formation of the observed quantity of secondary phases requires additional sources for Si, Fe. Ca and K. K is provided in excess from the inflowing seawater at reasonable water/rock ratios. The remaining excess Ca, Si and Fe required may be derived by alteration of interstitial glass and breakdown of anorthite rich plagioclase and titano-magnetite, and/or by supply of deeper seated metamorphic reactions.     

Effects of summer precipitation on urban transportation

Potential shifts in summer precipitation due to an enhanced greenhouse effect indicate the possibility of more rain days and heavier rains in the Midwest, and this study assessed the effects of such changes on transportation in Chicago using a 3-year period of data. Traffic accidents in the metropolitan area doubled on rainy days, with 30% more accidents in more densely populated urban areas than in suburban-rural areas. During rain events accident severity (number of injuries) was 55% higher in suburban and rural areas where less dense but higher speed traffic flows exist than in the city, however. Rain days during dry months produced more accidents and injuries than during normal or wet months. Three times as many accidents occurred during heavy rain periods (> 12.8 mm) as during nonrain conditions. Rain had a negligible influence on weekday traffic volume on busy highways but there was a 9% decrease in traffic volume on rainy weekends. A 3–5% decrease in ridership of public transportation occurred on rainy days, with most decreases during midday. Nationally, 27% of all fatality-producing aircraft accidents occurred during rainy weather conditions, as did 57% of the 30-min flight delays at Chicago's O'Hare Airport. Results suggest that given continued transportation use patterns extend into the future, a future climate with more summer rain days, somewhat higher rain rates, and more storms would mean more total vehicular accidents, more total injuries in vehicular accidents, decreased ridership on public transportation systems, and more aircraft accidents and delays. A drier climate would likely experience fewer moderate to heavy rain events but results show that rain events during drier conditions produced a greater frequency of accidents and injuries per event than during wetter conditions.     

The Great Lakes diversion at Chicago and its implications for climate change

In 1900 the city of Chicago began diverting sizable amounts of water from Lake Michigan to move its sewage down the Illinois River. This diversion launched a series of continuing legal controversies involving Illinois as a defendant against claims by the federal government, various lake states, and Canada who wanted the diversion stopped or drastically reduced. During the past 96 years extended dry periods have lowered the lake levels. Using these dry periods as surrogates for future conditions, their effects on the past controversies were examined as analogs for what might occur as a result of climate change from an enhanced Greenhouse effect. The results reveal that changing socioeconomic factors including population growth will likely cause increased water use, and Chicago will seek additional water from the Great Lakes. New priorities for water use will emerge as in the past. Drier future conditions will likely lead to enhanced diversions from the Great Lakes to serve interests in and outside the basin. Future lower lake levels (reflecting a drier climate) will lead to conflicts related to existing and proposed diversions, and these conflicts would be exacerbated by the consequences of global warming. In any event, a warmer, drier climatic regime will challenge existing laws and institutions for dealing with Great Lakes water issues.     

Storm catastrophes in the United States

A unique historical data set describing the 142 storms each producing losses in excess of $100 million in the United States during the 1950–89 period were analyzed to describe their temporal characteristics. The storms caused $66.2 billion in losses (in 1991 values), 76% of the nation's insured storm losses in this period. These extreme storm catastrophes (SCs) were most prevalent in the south, southeast, northeast, and central U.S., with few in and west of the Rocky Mountains. Storm incidences were high in the 1950s, low in the 1960s-early 1970s, and increased in the 1980s. Losses due to SCs peaked in the 1950s, again in the late 1960s, with a lesser peak after 1985. The areal extent of storm losses peaked after 1975 and was least in the 1960s. The temporal variations of the three storm measures (incidence, losses, and extent) did not agree except when they all peaked in the 1950s. Regionally-derived time distributions of SCs showed a marked north-south differences in the United States with a U-shaped 40-year distribution in the northern half of the nation, and a relatively flat trend until a peak in the 1980s in the southern regions. The temporal distributions of hurricane-caused catastrophes differed regionally with occurrences in the prime areas, the southern, southeastern, and northeastern U.S., each quite different. Temporal distributions of thunderstorm and winter storm catastrophes were regionally more uniform.     

Stratification and bottom-water hypoxia in the Pamlico River estuary

Relationships among bottom-water dissolved oxygen (DO), vertical stratification, and the factors responsible for stratification-destratification in this shallow, low tidal-energy estuary were studied using a 15-yr set of biweekly measurements, along with some recent continuous-monitoring data. Hypoxia develops only when there is both vertical water-column stratification and warm water temperature (>15°C). In July, 75% of the DO readings were <5 mg 1^?1, and one-third were <1 mg 1^?1. Severe hypoxia occurs more frequently in the upper half of the estuary than near the mouth. Both the time series data and correlation analysis results indicate that stratification events and DO levels are tightly coupled with variations in freshwater discharge and wind stress. Stratification can form or disappear in a matter of hours, and episodes lasting from one to several days seem to be common. Estimated summertime respiration rates in the water and sediments are sufficient to produce hypoxia if the water is mixed only every 6–12 d. There has been no trend toward lower bottom water DO in the Pamlico River Estuary over the past 15 yr. *** DIRECT SUPPORT *** A01BY059 00002     

New dimensions in world shipbuildingNeue größenordnungen im welt-schiffbauNouvelles dimensions dans le monde des constructions navales

New classes of bulk carriers and general cargo vessels are becoming more specialized and larger. The trend towards containerizing cargo has spurred construction of the large cellular containership, the roll-on/roll-off vessel, and the barge carrying ship (LASH). Bulk vessels, especially tankers, have undergone tremendous increases in size until few of the newer ones can pass through the Suez Canal. Crews have not increased primarily because of greater use of shipboard automation devices. Few ports have sufficient water depths to accommodate supertankers, necessitating more off-loading at sea and construction of new deep water terminals. Japanese yards dominate world supership construction, with Scandinavian shipyards most important in Europe. Substantial supership construction is taking place in southern Europe and is an indication of the recent economic growth of Italy, Spain and Yugoslavia. Supership construction in Great Britain has declined relative to Scandinavian and Japanese production and that in the United States is of little significance worldwide.     

Carbon monoxide on the primitive earth

The reaction of CO + OH^? in aqueous solution to give formate was studied as a carbon monoxide sink on the primitive earth and in the present ocean. The reaction is first order in OH^? and first order in the molar CO concentration. The second order rate constant is given by log k(M^?1hr^?1) = 15.83?4886/T between 25°C and 60°C. Using the solubility of CO in sea water, and assuming a pH of 8 for a primitive ocean of the present size, the halflife of CO in the atmosphere is calculated to be 12 × 10⁶ yr at 0°C and 5.5 × 10⁴ yr at 25°C.Three other CO sinks would have been important in the primitive atmosphere: CO + H₂ → H₂CO driven by various energy sources, CO + OH → CO₂ + H, and the Fischer-Tropsch reaction of CO + H₂ → hydrocarbons, etc. It is concluded that the lifetime of a CO atmosphere would have been very short on the geological time scale although the relative importance of these four CO sinks is difficult to estimate.The CO + OH^? reaction to give formate is a very minor CO sink on the earth at the present time.     

Characteristics of electron and high-energy proton flares

High-energy proton (E _p > 55 MeV) and electron (E _e > 50 keV) events were observed by University of Iowa experiments on the satellites Explorer 33 and 35. The solar X-ray (2–12 Å) flares associated with the energetic proton events were found to have in general higher peak fluxes, considerably longer decay times (t) and smaller rise to decay time ratios (r) than the X-ray flares associated with the electron events. The most common decay times and rise to decay time ratios are: 80 t 100 min, 0.1 r 0.2 for the proton X-ray flares and t 20 min, 0.3 r 0.7 for the electron ones.