Some physical and chemical characteristics of an arctic beaded stream

Imnavait Creek is a tundra stream in the Arctic Foothills of Alaska. The stream is beaded, i.e. consists of pools (up to ∼ 2 m deep) connected by narrow channels. Peat dominates pool and channel substrate materials with occasional rock and moss substrates. The watershed is underlain by ice-bonded till and is hydrologically watertight. Because of low rates of weathering, bedrock and till do not contribute significantly to ionic composition of the stream water. Breakup occurs in late May to early June with surface flow until September. During periods of low rainfall, channel flow is reduced and pools become hydrologically isolated and thermally stratified (with very high surface water temperatures). Streamwater is acidic (pH values 5.3–6.1) with very low alkalinity (≤3 mg l⁻¹). The major transport of ions occurs in early flow derived from snow melt. Organic carbon concentrations are high with very high ratios of dissolved to particulate organic carbon. Dissolved inorganic nitrogen concentrations appear to be very low. High concentrations of dissolved organic material may indicate a central role for DOM in trophic dynamics.     

Some physical and chemical properties of trypsin-digested nucleoprotein

A DNA-peptide complex that is soluble in 0.2m-sodium chloride can be prepared by trypsin digestion of calf thymus nucleoprotein. The trypsin-digested nucleoprotein molecule contains about 70% of DNA and 30% of peptides by weight, and consists of one DNA molecule associated with arginine-rich peptides. A series of trypsin-digested nucleoprotein preparations differing only in molecular weight were prepared by blending. The intrinsic viscosity and average sedimentation coefficient were determined for each of these preparations. Then the DNA was isolated from each preparation and the hydrodynamic measurements were repeated on the DNA. From a comparison of these results it was concluded that the presence of the complex-forming peptides causes a large decrease in intrinsic viscosity of the DNA and an increase in sedimentation coefficient. In addition, the hydrodynamic data indicate that the DNA-peptide complex behaves like a coil in solution but is more compact than the same length of DNA. The ;melting' profiles, streptomycin precipitation curves and maximum viscosities obtained with ethidium bromide binding for the trypsin-digested nucleoprotein are similar to those of purified DNA, and markedly different from those of undigested nucleoprotein. These findings suggest that the peptides are not strongly associated with the DNA, and that secondary valency forces are involved in the binding.     

Some chemical,enzymic, and physical properties of di-saccharides from beef-lung heparin

A study is reported of the reactivities of the disaccharides isolated after deamination of beef-lung heparin and reduction of the products by sodium borotritide: 2,5-anhydro-O-(α-l-idopyranosyluronic acid sulfate)-d-mannitol sulfate, SIMS; 2,5-anhydro-O-(α-l-idopyranosyluronic acid)-d-mannitol sulfate, IMS; 2,5-anhydro-O-(α-l-idopyranosyluronic acid sulfate)-d-mannitol, SIM; and 2,5-anhydro-O-(β-d-glucopyranosyluronic acid)-d-mannitol sulfate, GMS. Results for the non-sulfated disaccharides IM and GM, prepared by desulfation of SIMS and GMS, are also reported. SIMS and SIM were inert to purified α-l-iduronidase, showed unexpected resistance to periodate oxidation, and lost sulfate rapidly in 50mm hydrochloric acid at 100°. Hydrolysis of IM and of IMS was catalyzed by α-l-iduronidase, and of GM and GMS by β-d-glucuronidase; the radioactive products were identified as 2,5-anhydro-d-mannitol (aM) and its sulfate (aMS). The products SIM and IMS obtained by deamination of heparin and desulfation of SIMS (the major deamination product) are apparently identical. In heparin partially desulfated by methanolic hydrogen chloride, residual sulfate groups were mostly linked to l-iduronic acid residues. Chemical, chromatographic, and electrophoretic methods that are valuable for separation and characterization of the disaccharides are described.     

Storage of oil field-produced waters alters their chemical and microbiological characteristics

Many oil fields are in remote locations, and the time required for shipment of produced water samples for microbiological examination may be lengthy. No studies have reported on how storage of oil field waters can change their characteristics. Produced water samples from three Alberta oil fields were collected in sterile, industry-approved 4-l epoxy-lined steel cans, sealed with minimal headspace and stored under anoxic conditions for 14 days at either 4°C or room temperature (ca. 21°C). Storage resulted in significant changes in water chemistry, microbial number estimates and/or community response to amendment with nitrate. During room-temperature storage, activity and growth of sulfate-reducing bacteria (and, to a lesser extent, fermenters and methanogens) in the samples led to significant changes in sulfide, acetate and propionate concentrations as well as a significant increase in most probable number estimates, particularly of sulfate-reducing bacteria. Sulfide production during room-temperature storage was likely to be responsible for the altered response to nitrate amendment observed in microcosms containing sulfidogenic samples. Refrigerated storage suppressed sulfate reduction and growth of sulfate-reducing bacteria. However, declines in sulfide concentrations were observed in two of the three samples stored at 4°C, suggesting abiotic losses of sulfide. In one of the samples stored at room temperature, nitrate amendment led to ammonification. These results demonstrate that storage of oil field water samples for 14 days, such as might occur because of lengthy transport times or delays before analysis in the laboratory, can affect microbial numbers and activity as well as water sample chemistry.     

Winter limnology: a comparison of physical,chemical and biological characteristics in two temperate lakes during ice cover

The winter dynamics of several chemical, physical, and biological variables of a shallow, polymictic lake (Opinicon) are compared to those of a deep, nearby dimictic lake (Upper Rock) during ice cover (January to early April) in 1990 and 1991. Both lakes were weakly inversely thermally stratified. Dissolved oxygen concentration was at saturation (11–15 mg l⁻¹) in the top 3 m layer, but declined to near anoxic levels near the sediments. Dissolved oxygen concentrations in the deep lake were at saturation in most of the water column and approached anoxic levels near the sediments only. Nutrient concentrations in both lakes were fairly high, and similar in both lakes during ice cover. Total phosphorus concentrations generally ranged between 10–20 μg l⁻¹, NH₄-N between 16–100 μg l⁻¹, and DSi between 0.9–1.9 mg l⁻¹; these concentrations fell within summer ranges. NO₃-N concentrations were between 51–135 μg l⁻¹ during ice cover, but occurred at trace concentrations (<0.002 μg l⁻¹) during the summer. The winter phytoplankton community of both lakes was dominated by flagellates (cryptophytes, chrysophytes) and occasionally diatoms. Dinoflagellates, Cyanobacteria and green algae were poorly represented. Cryptophytes often occurred in fairly high proportions (20–80%) throughout the water column, whereas chrysophytes were more abundant just beneath the ice. Zooplankton population densities were extremely low during ice cover (compared to maximum densities measured in spring or summer) in both lakes, and were comprised largely of copepods.