Influence of salinity on atrazine toxicity to a Chesapeake Bay copepod (Eurytemora affinis) and fish (Cyprinodon variegatus)

The objective of this study was to determine the influence of a range of salinities (5%., 15%., and 25%.) on the acute toxicity of atrazine to nauplii of the copepodEurytemora affinis and larvae of the sheepshead minnow,Cyprinodon variegatus. Ninety-six-hour LC50 values for the copepod were 0.5 mg 1^?1, 2.6 mg 1^?1, and 13.2 mg 1^?1 at salimities of 5%., 15%. and 25%. respectively. A comparison of LC50 values between adjacent salinities showed a statistical difference between 15%. and 25%. but not between 5%. and 15%.. Atrazine was more toxic toE. affinis at the lowest salinity. The 96-h LC50s for the sheepshead minnow were 16.2 mg 1^?1, 2.3 mg 1^?1, and 2.0 mg 1^?1 at salinities of 5%., 15%., and 25%., respectively. There was a statistical difference between LC50 values at 5%. and 15%. but not between 15%. and 25%.. In contrast toE. affinis results, atrazine was more toxic toC. variegatus at the highest salinity. The toxicity data from these species suggest that development of estuarine water quality criteria is warranted.     

Measurement of elastic properties of single-crystal CaO up to 1200 K

The elastic moduli of a single-crystal calcium oxide, CaO, are measured in the temperature range from 300 to 1200 K (1.8 times of the Debye temperature) by the resonant sphere technique (RST). The lowest 18 modes are identified in the frequency range from 0.6 to 1.4 MHz for the vibrating spherical specimen, which is 5.6564 mm in diameter and 3.3493 g/cm³ in density at room temperature, and the resonant frequencies are traced as a function of temperature. The adiabatic elastic moduli are determined in the present temperature range from the observed frequencies by inversion calculations. Most of the elastic moduli, except forC ₁₂ modulus, decrease as temperature increases. The temperature curves ofC _s andC ₄₄ moduli cross at 372 K. This means that the CaO specimen has an isotropic elasticity at the temperature. The temperature derivatives (?C ₁₁/?T) _P and (?C _s/?T) _P become slightly less negative with temperature increase and (?C _s /?T) _P and (?C ₄₄/?T) _P are almost constant. Combining the present elastic data with thermal expansion and specimen heat capacity data of CaO, we present the temperature dependence of thermodynamic parameters important in the studies of earth's interior.     

The future use of refrigeration in British coal mines

Summary This paper examines the methods presently available to apply refrigeration to a longwall district of a coal mine with particular reference to both the sources of heat and humidity around a district, and the specific locations which require cooling. Other methods to improve climatic conditions are also investigated and computer-predicted results from a district temperature prediction program are used for discussion.An approach to the solution of a climatic problem is explained with reference to other coal mine contaminants and an environmental design philosophy for deep high production districts in British coal mines is described.     

Enhancing the credibility of ecology: Interacting along and across hierarchical scales

A wide range of space and time scales characterize the processes and phenomena which interact to shape environmental condition and trends. Important perspectives of environmental space and time include the role of terrestrial and astronomical factors in shaping climatic change, insights to be gained from the pre-historical record, relations between disturbance and biotic responses, episodic extreme events and large-scale phenomena, cumulative impacts, fast — slow processes and memory reservoirs. Scales in physical, chemical and biological phenomena have parallels in human driving forces, societal relations and decision — making processes, and environmental scales of space and time thus have perceptual as well as physical (objective) dimensions. Scale is clearly more than just size and dimension, and there is a growing body of examples on how zooming along and across hierarchical scales can help in seeking explanation (how) and significance (why), and in revealing emergent properties. Scaling can also act as a motor for new approaches to scientific cooperation. Such evolving scales in scientific cooperation are examined in relation to three international research programmes (IBP, MAB, IGBP), to various sub-disciplines of ecology and biogeography, and to the restructuring of a largish research institute in Montpellier (France). An overall conclusion is that scaling issues may provide a stimulus to increased coherence within the science of ecology itself, and may facilitate mutually supportive links with other scientific domains and society at large.The views expressed are those of the authors and not necessarily those of the authors' employers.     

Spring melt patterns in the Kara/Barents Sea: 1984

Ice-atmosphere interactions in the Seasonal Sea Ice Zone undergo rapid changes during the spring melt period with the transition from winter to summer conditions. The nature of these interactions is strongly dependent on the characteristics of the surface, which also experiences large changes during this same time period. This paper describes a methodology, based on Extended Principal Components Analysis, which is used to categorize the spatial and temporal patterns of surface change that occur in the Seasonal Sea Ice Zone during the spring/early summer. The methodology is demonstrated for the Kara/Barents Sea in spring 1984 using data from the Nimbus-7 Scanning Multichannel Microwave Radiometer. The analysis shows conditions in the Barents Sea to be largely controlled by ice advection, while the variance in the Kara Sea is dominated by surface melt.     

Late cretaceous and tertiary history and the dynamic crushing of cobbles, black butte area, southwestern Montana

Black Butte is an early Miocene basaltic volcanic neck that forms a prominent landmark as the highest peak of the Gravelly Range, southwestern Montana. The intrusion cuts mid-Cenozoic and older sedimentary rocks near the eastern margin of the Overthrust Belt.

After erosional removal of the Late Cretaceous Frontier Formation, quartzite-rich detritus from ultimate sources probably far to the west was deposited in the area and now forms a diamicton that rests on striated bedrock. This unit, previously interpreted as a till and as a mudflow deposit, probably represents Upper Cretaceous or lower Tertiary, syntectonic alluvial-fan sediments. These were deposited after the Gravelly Arch had begun to rise and were deformed during overthrusting from the west or possibly during mass movement as the basal part of a landslide.

Scattered cobbles of hard quartzite in the diamicton are crushed. If this crushing occurred within aggregates of coarse clasts that were momentarity in point contact with one another, it does notrequire either overthrusting or mass movement of extremely thick depositional overburden. But if a major thrust sheet did move over the diamicton, the leading edge of the Overthrust Belt must extend considerably further east of where it is currently recognized in this area.

Volcanic and volcaniclastic rocks were deposited in the area throughout much or all of Oligocene time. These include tuffaceous mudstone as much as 265 m thick that contains vertebrate fossils of Chadronian through Whitneyan age. The KAr age of biotite in an airfall tuff within this section at nearby Lion Mountain is 31.4 Ma, and the KAr age of an alkaline basaltic flow at the top of the Lion Mountain section is 30.8 Ma. These tuffaceous rocks and basalt on Lion Mountain correlate with volcaniclastics in Wyoming and as far east as Nebraska and the Dakotas.

Eruptions at Black Butte, dated previously at 22.9 Ma, begun with phreatomagmatic explosions that deposited tuff across an irregular topographic surface cut in the section of tuffaceous mudstone into which the Black Butte plug was emplaced. The alkali basalt magma differentiated to yield the relatively rare rock typetephritic phonolite during fractional crystallization and segregation in situ of potassic late liquids.

Lava flows from Black Butte and the nearby Lion Mountain volcanic center may have covered much of this part of the Gravelly Range but have been mostly removed owing to erodability of the thick blanket of mudstone on which they rested.

Removal of mudstone that contained the Black Butte intrusion involved massive slumping. Mass movement of the diamicton beneath the mudstone is occurring today as an earthflow down the west-dipping structural and topographic slope of the range.