Treatment of saline, acidic, metal-contaminated groundwater from the Western Australian Wheatbelt.

Managing acidic, metal-containing saline ground and drainage waters in the Wheatbelt of Western Australia is an environmental and economic challenge. Sulfate-reducing fluidised bed bioreactors are shown to be technically capable of treating high salt, low pH, metal containing waters from the town of Narembeen in the Wheatbelt so as to reduce acidity and to remove most of the undesirable metal contaminants. The hydraulic residence time (HRT) limit for a stable process with groundwater from the region of Narembeen was >16 hours. The maximal rate of sulfate reduction in the laboratory system treating Narembeen groundwater was similar to rates observed in comparable applications of the process at other sites, ca. 3 g sulfate (L-reactor)(-1) day(-1). Salts that are relatively free of metal contaminants can be produced from water that has been treated by the sulfate-reducing fluidised bed bioreactor. It is unlikely that metal precipitates, captured from Wheatbelt waters by the process, would be of economic value. If sulfate-reducing fluidised bed reactors were considered technologically appropriate at larger scale, the decision to use them would be based on the necessity to take action, the comparative effectiveness of competing technologies, and the relative costs of competing technologies.

The isolation and use of iron-oxidizing, moderately thermophilic acidophiles from the Collie coal mine for the generation of ferric iron leaching solution.

Moderately thermophilic, iron-oxidizing acidophiles were enriched from coal collected from an open-cut mine in Collie, Western Australia. Iron-oxidizers were enriched in fluidized-bed reactors (FBR) at 60 degrees C and 70 degrees C; and iron-oxidation rates were determined. Ferrous iron oxidation by the microbiota in the original coal material was inhibited above 63;C. In addition to four iron-oxidizers, closely related to Sulfobacillus spp that had been earlier isolated from the 60 degrees C FBR, one heterotroph closely related to Alicyclobacillus spp was isolated. The Alicyclobacillus sp. isolated from the Collie coal mine tolerated a lower pH than known Alicyclobacillus spp and therefore may represent a new species. The optimum temperature for growth of the iron-oxidizing strains was approximately 50 degrees C and their maximum temperatures were approximately 60 degrees C. The FBR was adjusted to operate at 50 degrees C and was inoculated with all of the isolated iron-oxidizing strains. At 60 degrees C, an iron-oxidation rate of 0.5 g Fe(2+) l(-1) x h(-1) was obtained. At 50 degrees C, the iron-oxidation rate was only 0.3 g Fe(2+) l(-1) x h(-1). These rates compare favourably with the iron-oxidation rate of Acidianus brierleyi in shake-flasks, but are considerably lower than mesophilic iron-oxidation rates.

The role of microbial populations in the containment of aromatic hydrocarbons in the subsurface.

A survey of soil gases associated with gasoline stations on the Swan Coastal Plain of Western Australia has shown that 20% leak detectable amounts of petroleum. The fates of volatile hydrocarbons in the vadose zone at one contaminated site, and dissolved hydrocarbons in groundwater at another site were followed in a number of studies which are herein reviewed. Geochemical evidence from a plume of hydrocarbon-contaminated groundwater has shown that sulfate reduction rapidly developed as the terminal electron accepting process. Toluene degradation but not benzene degradation was linked to sulfate reduction. The sulfate-reducing bacteria isolated from the plume represented a new species, Desulfosporosinus meridiei. Strains of the species do not mineralise 14C-toluene in pure culture. The addition of large numbers of cells and sulfate to microcosms did stimulate toluene mineralisation but not benzene mineralisation. Attempts to follow populations of sulfate-reducing bacteria by phospholipid signatures, or Desulfosporosinus meridiei by FISH in the plume were unsuccessful, but fluorescently-labeled polyclonal antibodies were successfully used. In the vadose zone at a different site, volatile hydrocarbons were consumed in the top 0.5 m of the soil profile. The fastest measured rate of mineralisation of 14C-benzene in soils collected from the most active zone (6.5 mg kg(-1) day(-1)) could account for the majority of the flux of hydrocarbon vapourtowards the surface. The studies concluded that intrinsic remediation by subsurface microbial populations in groundwater on the Swan Coastal Plain can control transport of aromatic hydrocarbon contamination, except for the transport of benzene in groundwater. In the vadose zone, intrinsic remediation by the microbial populations in the soil profile can contain the transport of aromatic hydrocarbons, provided the physical transport of gases, in particular oxygen from the atmosphere, is not impeded by structures.

Desulfosporosinus meridiei sp. nov., a spore-forming sulfate-reducing bacterium isolated from gasolene-contaminated groundwater.

Eight strains of spore-forming, sulfate-reducing bacteria, isolated from groundwater contaminated with motor fuel [mostly benzene, toluene ethylbenzene and xylene (BTEX) compounds] in sandy soil near Perth, Australia, were closely related to Desulfosporosinus (previously Desulfotomaculum) orientis DSM 765T (95.3-97.3% 16S rDNA sequence similarity). Whole-cell fatty acids were dominated by even-carbon, straight-chain saturated and mono-unsaturated fatty acids, in particular 16:0, 16:1cis9, 14:0 and 18:1cis11. The strains grew at temperatures between 4 and 42 degrees C and in medium containing up to 4% NaCl. The eight strains clustered into two main groups based on phylogeny, randomly amplified polymorphic DNA (RAPD)-PCR patterns and nutritional characteristics. Representatives of the two groups, strain S5 (group A) and strain S10T (group B) had 81% DNA-DNA homology with each other and therefore should be accommodated in the same species. Strain S10T had less than 38% homology with Desulfosporosinus orientis DSM 765T, the most closely phylogenetically related type strain available. The new strains were distinguished from Desulfosporosinus orientis DSM 765T by different banding patterns in a RAPD-PCR, and phenotypically by their inability to utilize fumarate as a carbon and energy source with sulfate as the electron acceptor and by their lower tolerance to NaCl. The DNA G+C contents were 46.8 and 46.9 mol% for strains S5 and S10T, respectively (Desulfosporosinus orientis DSM 765T 45.9 mol%). It is proposed that these new strains be placed in a new species of the genus Desulfosporosinus. The name Desulfosporosinus meridiei is proposed, with strain S10T as the type strain (= DSM 13257T = NCIMB 13706T).

Spore-forming, Desulfosporosinus-like sulphate-reducing bacteria from a shallow aquifer contaminated with gasoline.

Previous studies on the geochemistry of a shallow unconfined aquifer contaminated with hydrocarbons suggested that the degradation of some hydrocarbons was linked to bacterial sulphate reduction. There was attenuation of naphthalene, 1,3,5-trimethylbenzene (TMB), toluene, p-xylene and ethylbenzene in the groundwater with concomitant loss of sulphate. Here, the recovery of eight strains of sulphate-reducing bacteria (SRB) from the contaminated site is reported. All were straight or curved rod-shaped cells which formed endospores. Amplification and sequencing of the 16S rDNA indicated that the strains were all sulphate reducers of the Gram-positive line of descent, and were most closely related to Desulfosporosinus (previously Desulfotomaculum) orientis DSM 8344 (97-98.9% sequence similarity). The strains clustered in three phylogenetic groups based on 16S rRNA sequences. Whole cell fatty acid compositions were similar to those of D. orientis DSM 8344, and were consistent with previous studies of fatty acids in soil and groundwater from the site. Microcosms containing groundwater from this aquifer indicated a role for sulphate reduction in the degradation of [ring-UL-14C]toluene, but not for the degradation of [UL-14C]benzene which could also be degraded by the microcosms. Adding one of the strains that was isolated from the groundwater (strain T2) to sulphate-enriched microcosms increased the rate of toluene degradation four- to 10-fold but had no effect on the rate of benzene degradation. The addition of molybdate, an inhibitor of sulphate reduction, to the groundwater samples decreased the rate of toluene mineralization. There was no evidence to support the mineralization of [UL-14C]benzene, [ring-UL-14C]toluene or unlabelled m-xylene, p-xylene, ethylbenzene, TMB or naphthalene by any of the strains in pure culture. Growth of all the strains was completely inhibited by 100 micromol l-1 TMB.

Synchronous movements of the longitudinal and circular muscle during peristalsis in the isolated guinea-pig distal colon.

1. Peristalsis, which involves enteric nervous reflexes, is the co-ordinated movements of the longitudinal (LM) and circular (CM) muscle layers that propel intraluminal contents down the bowel. Although the movements of the CM during peristalsis are reasonably clear the relative movements of the LM are poorly understood. 2. We studied the oral and anal movements of the LM and CM during a peristaltic wave in isolated segments of guinea-pig distal colon. Dissection techniques were used to prevent mechanical interactions between the LM and CM; also, the colonic segment was passed through a partition to prevent mechanical disturbances created by a peistaltic wave in the bulk of the colon from influencing the end from which recordings were made. 3. Peristalsis was generated by slowly filling the lumen of the colon with fluid. At threshold, the LM and CM synchronously contracted oral (ascending excitation) to, and relaxed anal (descending inhibition) to, a peristaltic wave. The anal relaxation was followed by a contraction (descending excitation) of both muscle layers. 4. Atropine (1 microM) in the recording chamber reduced both the oral (LM by 40% and CM by 27%) and anal (LM by 36% and CM by 36%) contractile responses as well as the anal relaxation response in both muscle layers. Hexamethonium (300 microM) almost blocked the oral contractile responses of the LM and CM but had no affect on the anal responses of either muscle layer. 5. N omega-nitro-L-arginine (L-NA; 100 microM) reduced the oral contractile response of the LM and CM by 50%, the anal contractile response of the LM by 30%, and the anal relaxation response of the LM and CM by about 30%. The anal contractile response of the CM was unaffected by L-NA. 6. Apamin (0.5 microM) also reduced the evoked anal relaxation of both the LM and CM by about 50%. Further addition of L-NA nearly abolished the relaxation response in the LM, but did not cause any further reduction in the relaxation response of the CM observed in apamin alone. 7. It is concluded, that the LM and CM exhibit synchronous movements during peristalsis in the colon. Also, peristalsis consists of activation of ascending excitatory, and descending inhibitory and excitatory nervous pathways to the LM and CM, which are cholinergic and non-cholinergic, respectively. Nitric oxide is an important neuromodulator within the intrinsic nervous pathways.

Prevalence of Giardia cysts and Cryptosporidium oocysts and characterization of Giardia spp. isolated from drinking water in Canada.

This study was carried out to estimate the prevalence and potential for human infectivity of Giardia cysts in Canadian drinking water supplies. The presence of Cryptosporidium oocysts was also noted, but isolates were not collected for further study. A total of 1,760 raw water samples, treated water samples, and raw sewage samples were collected from 72 municipalities across Canada for analysis, 58 of which treat their water by chlorination alone. Giardia cysts were found in 73% of raw sewage samples, 21% of raw water samples, and 18.2% of treated water samples. There was a trend to higher concentration and more frequent incidence of Giardia cysts in the spring and fall, but positive samples were found in all seasons. Cryptosporidium oocysts were found in 6.1% of raw sewage samples, 4.5% of raw water samples, and 3.5% of treated water samples. Giardia cyst viability was assessed by infecting Mongolian gerbils (Meriones unguiculatus) and by use of a modified propidium iodide dye exclusion test, and the results were not always in agreement. No Cryptosporidium isolates were recovered from gerbils, but 8 of 276 (3%) water samples and 19 of 113 (17%) sewage samples resulted in positive Giardia infections. Most of the water samples contained a low number of cysts, and 12 Giardia isolates were successfully recovered from gerbils and cultured. Biotyping of these isolates by isoenzyme analysis and karyotyping by pulsed-field gel electrophoresis separated the isolates into the same three discrete groups. Karyotyping revealed four or five chromosomal bands ranging in size from 0.9 to 2 Mb, and four of the isolates had the same banding pattern as that of the WB strain. Analysis of the nucleotide sequences of the 16S DNA coding for rRNA divided the isolates into two distinct groups corresponding to the Polish and Belgian designations found by other investigators. The occurrence of these biotypes and karyotypes appeared to be random and was not related to geographic or other factors (e.g., different types were found in both drinking water and sewage from the same community). Biotyping and karyotyping showed that isolates from this study were genetically and biochemically similar to those found elsewhere, including well-described human source strains such as WB. We conclude that potentially human-infective Giardia cysts are commonly found in raw surface waters and sewage in Canada, although cyst viability is frequently low. Cryptosporidium oocysts are less common in Canada. An action level of three to five Giardia cysts per 100 liters in treated drinking water is proposed on the basis of the monitoring data from outbreak situations. This action level is lower than that proposed by Haas and Rose (C. N. Haas and J. B. Rose, J. Am. Water Works Assoc. 87(9):81-84, 1995) for Cryptosporidium spp. (10 to 30 oocysts per 100 liters).

The concept of guilt.

1. Guilt is an uncomfortable feeling resulting from the commission or contemplation of a specific act contrary to one's internalized standards of conduct; it requires reparative action for the harm done to another to alleviate the uncomfortable feeling (distress). 2. The terms guilt and shame often are used interchangeably, but psychologic theory and phenomenologic studies clearly indicate that these are distinctly different affective experiences. Shame arises from the self's negative evaluation of the self (an evaluation that may or may not have been instigated by actual public exposure); guilt arises from the self's negative evaluation of specific behaviors or transgressions. 3. The psychiatric nurse is in an excellent position to intervene effectively with clients who are struggling with the emotional effects of guilt, and the psychiatric nurse can be instrumental in breaking the lifelong cycle of dysfunctional guilt feelings.

The relationship between three potential pathogens and pollution indicator organisms in Nova Scotian coastal waters.

Fifteen stations, in two estuaries, along the Northumberland Strait of Nova Scotia were examined between June and September 1981 for a relationship between the concentrations of commonly monitored fecal indicator bacteria and the potential pathogens Candida albicans, Pseudomonas aeruginosa, and Vibrio parahaemolyticus. Increased densities of these three organisms were usually associated with high densities of indicator bacteria. Whereas C. albicans and P. aeruginosa occur in human fecal wastes, V. parahaemolyticus is indigenous to the marine environment and positively responds to elevated nutrient levels in sewage. There is also some evidence that these bacteria survive as long or longer in marine waters than the common indicator bacteria. While membrane-filtration techniques for the enumeration of C. albicans and P. aeruginosa proved satisfactory, a V. parahaemolyticus membrane-filtration method lacked specificity and was supplemented by a most-probable-number method. In marine recreational and shellfish waters, these three organisms could complement fecal coliforms and fecal streptococci as indicators of human fecal contamination.