Physiological responses ofCalanus finmarchicus andMetridia longa (Copepoda: Calanoida) during the winter-spring transition

The effect of pH on the biological availability of copper to the brine shrimp Artemia franciscana was studied with acclimated and non-acclimated individuals for the pH range 5.5 to 8.5. A chemical speciation model was used to calculate the speciation of copper in a chemically-defined saline solution as a function of pH. The lipid solubility of inorganic copper species was determined in hexadecane/saline and octanol/saline extraction systems. Copper is absorbed across the gut epithelium and accumulation is proportional to time over a 120 min experimental period. The biological availability of copper decreases with a decrease in the pH of the salt solution and a concomitant increase of the cupric ion concentration. Acclimation to the experimental pH has a marked effect on the uptake process, which depends on the buffer used. There is no extraction of copper in hexadecane, but a small amount goes in octanol. There is, however, no direct relation between the accumulation of copper in the shrimps and the extraction of copper in octanol. Multiple regression of the accumulation rates for non-acclimated animals on the calculated copper species concentrations shows that much of the variation in accumulation rate with pH is explained when copper hydroxide and/or copper carbonate species are considered to be the biologically available forms. Alternatively, the observations can be interpreted as the result of competitive binding of protons and copper species for carrier systems.     

Integrated assessment of the grand nutrient cycles

There are four major elements that are required by the biosphere in significantly greater quantities than they are available in nature. These four are carbon (C), nitrogen (N), sulfur (S) and phosphorus (P). (Hydrogen and oxygen, the other two major ingredients of organic materials, are not scarce in the earth's crust, though oxygen is also recycled along with carbon.) These natural cycles are driven by geological, hydrological, atmospheric and biological processes. In effect, the geo‐biosphere is a dissipative system (in the sense of Prigogine) in a quasi steady state, far from thermodynamic equilibrium. This steady state is maintained by the influx of solar exergy. Interruption or disturbance of these natural cycles as a consequence of human industrial/economic activity could adversely affect the stability of the biosphere, and might possibly reduce its productivity. Indeed, because the more complex long‐lived organisms such as large mammals (including man), birds and even trees evolve more slowly than smaller short‐lived organisms, the very nature of an altered steady state might not be favorable to many existing species. Thus there is even a potential threat to human survival itself. Unfortunately, the interactions among these cycles have received relatively little attention up to now.     

Bioventing pilot test results at the low point drain area at Offutt AFB,Nebraska

Bioventing is a relatively new technology that uses forced air movement to deliver supplemental oxygen to contaminated soils to stimulate the biodegradation of contaminants by indigenous microorganisms. A bioventing pilot test was initiated at Offutt Air Force Base, Nebraska, in August 1992, at a site contaminated with jet fuel. Air was injected into the subsurface over a period of 15 months, and tests were conducted at 6 months, and again at 15 months, to determine the effectiveness of the system. This article describes the bioventing process and its application at this test site. The results of the pilot test are discussed to illustrate the extent of the remediation accomplished through bioventing.     

Induction of cytochrome P-450 and phosphatidylcholine synthesis by endosulfan in liver of rats: effect of quality of dietary proteins

Administration of endosulfan significantly increased microsomal protein, cytochrome P-450 content and the activity of aminopyrine N-demethylase. Effect of endosulfan and actinomycin D either alone or together on microsomal protein, cytochrome P-450, NADPH cytochrome c reductase, aniline hydroxylase, aminopyrine N-demethylase, phosphatidylcholine content, incorporation of 3H-choline and 14C-methionine were studied in rats given amino acid deficient and supplemented diets. Administration of endosulfan significantly increased the above parameters in both the dietary groups, whereas administration of actinomycin D did not have any effect in rats fed supplemented diets, however, significant decrease in the PC and the incorporation of choline and methionine into PC of rats fed deficient diet were observed. A positive correlation in the effect of endosulfan on hepatic mixed function oxidase activity and hepatic phosphatidylcholine is observed.