An Automated Technique for Delineating and Characterizing Valley-Bottom Settings

Accurate delineation and characterization of valley-bottom settings is crucial to the assessment of the biological and geomorphological components of riverine systems; yet, to date, most valley-bottom mapping endeavors have been done manually. To improve this situation, we developed automated techniques in a Geographic Information System (GIS) for delineating and characterizing valley-bottom settings in river basins ranging in size from approximately 1,000–10,000 km². All procedures were developed with ARC/INFO GIS software and fully automated in Arc Macro Language (AML). The GRID module is required for valley-bottom delineation and slope calculations; whereas characterization (i.e., measuring the width of the valley-bottom zone) requires Coordinate Geometry (COGO) in the ARCEDIT module. The process requires three inputs: a polygon coverage of the analysis area; an arc coverage of its hydrography, and a grid representing its digital elevation. The AML is designed to operate within a wide range of computer memory/disk space options, and it allows users to customize several procedures to match the scale and complexity of a given analysis area with available computer hardware.     

The measurement of intracellular zinc in human intestinal mucosa using x-ray microanalysis

The zinc content of intestinal epithelial cells in human jejunum and ileum has been measured using X-ray microanalysis. The range of values was wide, the highest being found in stem cells and enterocytes. Significant differences were found in jejunum from gastric carcinoma patients and ileum from Crohn's disease patients compared with patients with non malignant, non inflammatory disease.     

Electro-remediation of tailings from a multi-metal sulphide mine: comparing removal efficiencies of Pb,Zn, Cu and Cd

Sulphidic mine tailings characterised by high concentrations of heavy metals (Pb 3532?±?97?mg/kg, Zn 8450?±?154?mg/kg, Cu 239?±?18?mg/kg and Cd 14.1?±?0.3?mg/kg) and abundant carbonate (17%) were subjected to eight lab-scale electrodialytic remediation (EDR) experiments to investigate the influence of current density, treatment time and particle size on removal efficiency. Pb and Cu removal improved when increasing current density, while Zn and Cd removal did not. In contrast Zn and Cd removal improved by grinding the tailings, while Pb and Cu removal did not. At the highest current density (1.2?mA/cm²), 94%, 75%, 71% and 67% removal of Pb, Zn, Cu and Cd could be achieved, respectively, on grinded tailings in 28 days. Sequential chemical extraction made before and after EDR revealed larger oxidisable fractions of Zn, Cu and Cd, representing large fractions of sulphides, which was likely to be the main barrier to be removed as efficiently as Pb. This was in accordance with acid/base extraction tests in which Pb showed high solubility at both high and low pH (up to 65% and 86% of extraction, respectively), while considerable extraction of Zn (55%) happened only at low pH; and very limited extraction (<20%) of Cu and Cd occurred at any pH.     

Possible causes of temporal fluctuations in primary production of the microphytobenthos in the Danish Wadden Sea

The effects of prior exposure to unlabelled naphthalene on the processes of uptake, tissue distribution and elimination of [1-¹⁴C] naphthalene by mussels (Mytilus edulis) were examined. Mussels collected from Whitsand Bay (S. W. England) in October 1980 were either held unexposed or exposed to unlabelled naphthalene (0.5 μg 1^?1) for 4 wk, prior to receiving a 4 h pulse of [1-¹⁴C] naphthalene in the medium (7 μg 1^?1). After 4 h exposure to [1-¹⁴C] naphthalene, the major tissues (digestive gland, gills, kidneys, mantle and remaining tissue) showed exponential depuration curves which could be resolved into two statistically significant components. The kinetics of elimination and the biological half-times of [1-¹⁴C] naphthalene in the tissues were determined. Mussels pre-exposed to unlabelled naphthalene had a significantly higher rate of elimination of [1-¹⁴C] naphthalene from the gills and kidneys. These results indicate that the toxicant, naphthalene, is actively excreted from the body by the gills and kidneys and the process is enhanced by prior exposure to the toxicant.     

Life history of the nematode Theristus anoxybioticus from sublittoral muddy sediment at methane seepages in the northern Kattegat,Denmark

Field and laboratory studies from 1989 to 1994 of the nematode Theristus (Penzancia) anoxybioticus Jensen, 1995 inhabiting muddy sediment at methane seepages in the northern Kattegat, Denmark, have revealed a series of biological features of adults and juveniles not observed before in free-living marine nematodes. Reproductive adults were present in April and May only and inhabited the uppermost cm of sediment, while juveniles inhabited deep anoxic and sulphidic sediment layers during the remaining months of the year. This points to a downwards migration of newly hatched juveniles and an upwards migration during adulthood. Gut content analyses showed that adults feed mainly on benthic diatoms by swallowing whole cells while juveniles probably feed on bacteria; this differentiation in food clearly relates to the main bulk of potential food items in their respective microhabitats. The generation time is estimated to be one year, with a juvenile life span of about nine months, which is four to eight times longer than that found in related aerobic species of similar body size. Adults survived in oxic water but 50% died within 15 h in hypoxic water (5 to 6% atm sat), and all died within 12 h in anoxic water. Juveniles on the other hand died within 0.5 h in oxic water but survived anoxic water for at least 15 d. These results suggest that juveniles of T. anoxybioticus are adapted to an anaerobic life style.     

Antimicrobial activities of extracts from tropical Atlantic marine plants against marine pathogens and saprophytes

Studies investigating disease resistance in marine plants have indicated that secondary metabolites may have important defensive functions against harmful marine microorganisms. The goal of this study was to systematically screen extracts from marine plants for antimicrobial effects against marine pathogens and saprophytes. Lipophilic and hydrophilic extracts from species of 49 marine algae and 3 seagrasses collected in the tropical Atlantic were screened for antimicrobial activity against five ecologically relevant marine microorganisms from three separate kingdoms. These assay microbes consisted of the pathogenic fungus Lindra thalassiae, the saprophytic fungus Dendryphiella salina, the saprophytic stramenopiles, Halophytophthora spinosa and Schizochytrium aggregatum, and the pathogenic bacterium Pseudoaltermonas bacteriolytica. Overall, 90% of all species surveyed yielded extracts that were active against one or more, and 77% yielded extracts that were active against two or more assay microorganisms. Broad-spectrum activity against three or four assay microorganisms was observed in the extracts from 48 and 27% of all species, respectively. The green algae Halimeda copiosa and Penicillus capitatus (Chlorophyta) were the only species to yield extracts active against all assay microorganisms. Among all assay microorganisms, both fungi were the most resistant to the extracts tested, with less than 21% of all extracts inhibiting the growth of either L. thalassiae or D. salina. In contrast, over half of all lipophylic extracts were active against the stramenopiles H. spinosa and S. aggregatum, and the bacterium P. bacteriolytica. Growth sensitivity to hydrophilic extracts varied considerably between individual assay microorganisms. While 48% of all hydrophilic extracts were active against H. spinosa, 27% were active against P. bacteriolytica, and only 14% were active against S. aggregatum. Overall, more lipophilic extracts inhibited microbial growth than hydrophilic extracts. The variability observed in the antimicrobial effects of individual extracts against each assay microorganism reflects the importance of choosing appropriate test microbes in assays from which ecologically relevant information is sought. Results from this survey demonstrate that antimicrobial activities are prevalent among extracts from marine algae and seagrasses, suggesting that antimicrobial chemical defenses are widespread among marine plants.     

Stabilization of APC residues from waste incineration with ferrous sulfate on a semi-industrial scale

A stabilization method for air pollution control (APC) residues from municipal solid waste incineration (MSWI) involving mixing of the residue with water and FeSO4 has been demonstrated on a semi-industrial scale on three types of APC residues: a semidry (SD) APC residue, a fly ash (FA), and an FA mixed with sludge (FAS) from a wet flue gas cleaning system. The process was performed in batches of 165-175 kg residue. It generates a wastewater that is highly saline but has a low content of heavy metals such as Cd, Cr, and Pb. The stabilized and raw residues have been subject to a range of leaching tests: the batch leaching test, the pH-static leaching test, the availability test, and the column test. These tests showed that the stabilized residues have remarkably improved leaching properties, especially with respect to Pb but also with respect to Cd, Cu, and Zn. The release of Pb was reduced by a factor of 250-36,000.     

Effect of sequencing batch reactor operation on presence and concentration of tetracycline-resistant organisms.

The effect of sequencing batch reactor operation on presence and concentration of tetracycline-resistant organisms was studied as a function of organic loading rate (OLR) and solids retention time (SRT), with and without supplemented influent tetracycline. These effects were evaluated using bacterial counts, bacterial production, system growth rate, and percent resistance. These evaluation parameters were applied to both intermediate resistant and resistant heterotrophs, enterics, and lactose fermenters. Tetracycline intermediate resistant and resistant bacteria are defined as the survival of colonies on agar with 5 and 20 mg/L tetracycline, respectively. Based on these studies, increases in influent tetracycline concentration and OLR resulted in amplification of tetracycline resistance. Decreases in SRT also resulted in amplification of tetracycline resistance.