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PubMed2000

Use of rubber dam and irrigant selection in UK general dental practice.

AIM: To evaluate factors which influence rubber dam use and irrigant selection in UK National Health Service (NHS) endodontics. METHODOLOGY: A postal survey was conducted amongst two age cohorts of dentists, representing all of the 1970-73 (older) and 1990-93 (younger) graduates of two northern English dental schools (n = 643). Key and supplementary questions were posed on levels of rubber dam use, irrigant selection, and factors influencing practice in NHS endodontics. After manual checking, validated (dual) entry of responses was made to a flat ASCII data file before analysis with SPSS software. The threshold for statistical significance was set at the 95% probability level. RESULTS: Eighty-five per cent of the valid sample responded to the questionnaire. Regardless of age and qualifying school, less than one-fifth of dentists always or frequently used rubber dam, whilst 60% never used it. Qualifying school had a significant influence on rubber dam use, whilst age had a variable influence. Major disincentives to the use of rubber dam included the perception that patients do not like it, that the NHS fee was inadequate to justify its use, that it took too long to apply, and that dentists had received inadequate training. Frequent users of rubber dam were significantly less likely to cite these disincentives than nonusers. Overall, local anaesthetic solution was the most common endodontic irrigant. Irrigant choice was strongly linked to rubber dam use, and to graduation cohort. Seventy-one per cent of rubber dam users irrigated with sodium hypochlorite, compared with only 38% of nonusers. This pattern was reversed for local anaesthetic irrigation. Younger graduates were significantly more likely to irrigate with local anaesthetic solution than their older counterparts, and the younger graduates of one school showed a highly significant increase in the use of chlorhexidine. CONCLUSIONS: 1) The majority of UK Health Service dentists never use rubber dam isolation in endodontic treatment. 2) Qualifying school has a significant impact on rubber dam use, and irrigant selection. 3) Use of rubber dam has a significant association with irrigant choice in endodontics.

Age Factors↗
PubMed2002

Radiofrequency catheter ablation using cooled electrodes: impact of irrigation flow rate and catheter contact pressure on lesion dimensions.

Irrigation of radiofrequency current (RF) ablation reduces the risk of thrombus formation. The aim of this study was to investigate the impact of different irrigation catheter flow rates and contact pressures from the catheter on the development of lesion dimension and thrombus formation. A thigh muscle preparation was achieved in six sheep to create a cradle that was filled and perfused with heparinized blood (250 mL/min, 37 C degrees). RF ablation (30 s, 30 W) was initially performed with three different irrigation flow rates (5 mL/min, 10 mL/min, and 20 mL/min) and a perpendicular position (0.1 N contact pressure) of the irrigated ablation catheter ("Sprinklr," Medtronic, Inc., Minneapolis, MN, USA). The next lesions were induced with constant contact pressure of 0.05 Newton (N); 0.1 N; 0.3 and 0.5 N and a parallel or perpendicular orientation of the catheter, respectively. A constant irrigation flow of 10 mL/min was maintained during these RF applications. Cross sections of the lesions were investigated with regard to maximal depth and maximal diameter at and below the surface. During high flow irrigation (20 mL/min) the surface diameter was significantly smaller (0.63 +/- 0.1 cm) compared to irrigation flowrates of 5 mL/min (0.88 +/- 0.2 cm) and 10 mL/min (1 +/- 0.1 cm). Thrombus formation was not observed during any RF application. Only in perpendicular catheter orientations with a contact pressure of 0.5 N were significantly deeper lesions (0.85 +/- 0.12 cm) induced compared to 0.05 N (0.55 +/- 0.02 cm), 0.1 N (0.7 +/- 0.01 cm) and 0.3 N (0.67 +/- 0.01 cm) contact pressure. There was no significant difference in lesion depth with different flow rates. Irrigated RF ablation even with low flow rates and high catheter contact pressure prevented thrombus formation at the electrode. Smaller lesion diameters have been created with high irrigation flow rates. The deeper lesion created with high catheter contact pressure might be caused by a greater power transmission to the tissue.

Animals↗
PubMed2001

Arthroscopic shoulder surgery with epinephrine saline irrigation.

PURPOSE: To determine whether dilute epinephrine saline irrigation (0.33 mg/L) delivered by a pressure-controlled pump would significantly reduce intraoperative bleeding during routine arthroscopic shoulder surgery and, in addition, to investigate potential adverse cardiovascular reactions of adding epinephrine to the irrigation fluid. TYPE OF STUDY: Prospective, randomized, double-blinded, placebo-controlled study. METHODS: Fifty-four patients requiring arthroscopic shoulder surgery were randomly assigned to either an epinephrine group that received dilute epinephrine irrigation by a pressure-controlled pump or to a placebo group that received plain saline irrigation by a pressure-controlled pump. Intraoperative, intra-articular bleeding was estimated by multiplying the total volume of the irrigation fluid used with the hemoglobin concentration in the irrigation fluid. Postoperatively, the surgeon rated the clarity of the visual field during the arthroscopy by a visual analogy scale. RESULTS: Intraoperative bleeding was significantly reduced (P =.008) and the clarity of the visual field was significantly better (P =.0007) in the group of patients receiving dilute epinephrine irrigation compared with the group of patients without epinephrine added to the irrigation fluid. CONCLUSIONS: The addition of epinephrine to irrigation fluid seems to reduce intra-articular bleeding during routine arthroscopic shoulder surgery and may improve visualization. Furthermore, no cardiovascular adverse reactions were observed resulting from the intra-articular epinephrine administration.

Adult↗
PubMed1985

Amikacin concentrations in serum following intraoperative irrigation of the pleura and peritoneum.

Serum concentrations of amikacin following operative wound irrigation were studied in 17 patients having laporatomy and in eight patients having thoracotomy. Irrigation was done with 500 mg of amikacin in 200 ml of saline. The irrigant was reaspirated after 3 minutes. Measurement of amikacin in the irrigant allowed calculation of the retained dose. Serum levels were measured before surgery, and at 30 minutes, 60 minutes, 6 hours, and 12 hours following irrigation. Amikacin was assayed by a microbiological technique. The retained dose after peritoneal irrigation was 350 +/- 128 mg, and after pleural irrigation was 100 +/- 79 mg. The average maximum serum level in the peritoneal irrigation group was 9.4 +/- 6.7 gm/ml; in the thoracotomy group it was 3.5 +/- 1.7. Fourteen of the 17 laparotomy patients but only one of the eight thoracotomy patients had measurable plasma levels at 6 hours. Plasma half-life in the laparotomy group was 2.81 +/- 1.34 hours, and in the thoracotomy group 1.53 +/- 0.83 hours. Interoperative amikacin irrigation, even with immediate aspiration, results in significant absorption in both thoracotomy and laporatomy patients. There was less absorption and a shorter serum half-life in the thoracotomy patients.

Absorption↗
PubMed2002

The effect of sodium hypochlorite irrigant concentration on tooth surface strain.

The effect of root-canal irrigation with different concentrations of sodium hypochlorite (3%, 5.1%, 7.3% NaOCI) on the mechanical properties of teeth was investigated in vitro. Root canals of 13 extracted, human premolars, denuded of enamel, were prepared with nickel-titanium rotary instruments (Quantec) to a standard size by using saline irrigation. An electrical strain gauge was bonded to the cervical aspect of each tooth. The 10 experimental teeth were subjected to 5 successive, 30-minute periods of irrigation. The irrigants were used in the following order: (a) saline; (b) 3.0% NaOCI; (c) 5.1% NaOCI; (d) 7.3% NaOCI; (e) saline. Three control teeth were irrigated with saline only for all five periods. After each irrigation, the teeth were cyclically loaded to 110N while the surface strain was measured. Changes in strain of the test teeth after each irrigation regimen followed broadly similar patterns that were different from the control teeth. There was no difference, however, in the strain recorded after irrigation by the different irrigants within the experimental group.

Analysis of Variance↗
PubMed1994

The efficacy of various irrigation solutions in removing slime-producing Staphylococcus.

To determine which type of irrigation solution and which method of irrigation most effectively removes slime-producing Staphylococcus from implant surfaces, we performed experimental washings of bacteria-coated stainless steel screws with various solutions delivered by bulb syringe or by jet lavage. The quantity of bacteria remaining on the screw surface was determined after irrigation with 1 L of saline, 1 L of antibiotic solutions, or 1 L of saline containing a liquid soap. Antibiotic solutions tested included bacitracin, neomycin, and polymyxin/neomycin. We found that the use of power irrigation increased the removal of bacteria by a factor of at least 100 over bulb syringe irrigation of the same volume, no matter which solution was used. This effect ranged from a 100-fold improvement for neomycin, to a 285-fold effect for the polymyxin solution. The addition of antibiotic drugs to the irrigation solution had no significant effect on bacterial removal, and none of the antibiotic solutions were statistically different from saline alone in the amount of bacteria removed from the screws. The addition of a liquid soap solution dramatically increased the amount of bacteria removed by irrigation, reducing the residual bacteria per screw from a colony count of 3.5 x 10(4) for polymyxin (the best of the antibiotic solutions), to 4.38 x 10(3). This difference was statistically significant as judged by Student's t test, with p = 0.01. We have concluded that the use of power irrigation improves the ability to clean this pathogenic bacteria from metallic surfaces, and that the addition of antibiotic drugs to the irrigation solution does not.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Bacterial Agents↗
PubMedDate not supplied

High pressure pulsatile lavage irrigation of intraarticular fractures: effects on fracture healing.

OBJECTIVES: To evaluate the effects of pulsatile lavage and bulb syringe irrigation on fracture healing in vivo. DESIGN: Randomized prospective trial in an animal model. SETTING: Medical school orthopaedic department. SUBJECTS: Thirty New Zealand white rabbits. INTERVENTION: The control group (C) underwent osteotomy of the medial femoral condyle, stabilization, and closure. The bulb syringe and pulsatile lavage groups underwent the same procedure as group C, with the addition of irrigation with one liter of normal saline via a bulb syringe (B) or a pulsatile lavage system (P). Animals were administered two fluorescent bone stains: xylenol orange at the time of operation, and calcein green one week postoperatively. Animals were euthanized two weeks postoperatively and femurs were retrieved for histological analysis. MAIN OUTCOME MEASURES: Union was determined by examination of microradiographs under light microscopy. The viability of bone along the fracture site was determined by evaluation of xylenol orange and calcein green staining under fluorescent microscopy. The density of new bone formed in the osteotomy site was assessed by computerized digitization of standardized regions of the proximal and distal osteotomy. RESULTS: Xylenol orange bands were present a mean of 66 +/- 8 percent (mean +/- standard error of the mean), 65 +/- 6 percent, and 44 +/- 5 percent of the distance along the osteotomy in groups C, B, and P, respectively (p < 0.001). Calcein green bands were present throughout the osteotomy site in all specimens. Calcified new bone was present in 62 +/- 4 percent, 58 +/- 7 percent, and 41 +/- 9 percent of the area measured in groups C, B, and P, respectively (p = 0.07). Twenty percent of the osteotomies in groups C and B did not unite, compared with 30 percent in group P (p > 0.5). CONCLUSIONS: Pulsatile lavage irrigation of fresh intraarticular fractures in rabbits has a detrimental effect on early new bone formation; this effect, however, is no longer apparent two weeks following irrigation. While this study evaluated the effects of pulsatile lavage irrigation in noncontaminated fractures without extensive soft tissue injury, the detrimental effects observed on early new bone formation may translate to an increased risk of nonunion in the setting of a contaminated open fracture with extensive soft tissue injury. Based on the results of this investigation, the selective use of pulsatile lavage irrigation appears warranted. In the absence of gross wound contamination, irrigation with a bulb syringe appears less likely to impair fracture healing than does pulsatile lavage irrigation. Expansion of the model used in this study to include bacterial contamination and soft tissue crushing may further elucidate the effects of pulsatile lavage irrigation on fracture healing.

Animals↗
PubMed2006

An ex vivo evaluation of a new root canal irrigation technique with intracanal aspiration.

AIM: To evaluate the effectiveness of a new root canal irrigation technique with intracanal aspiration in removing the smear layer and to assess irrigant extrusion ex vivo. METHODOLOGY: Thirty-five instrumented canals of extracted human canine teeth that had been resected apically by removing 3 mm of the root tip were divided into one control and four experimental groups of seven teeth each. The roots were fixed in a plastic case and surrounded with normal saline agar coloured with 1% acid red. No irrigation was performed in the control teeth. Each root canal in the experimental groups was irrigated with 9 mL of 14% ethylenediaminetetraacetic acid for 3 min, and then with 6 mL of 6% sodium hypochlorite (NaOCl) for 2 min. In the intracanal aspiration technique, the irrigant was delivered from the tip of an injection needle placed 12 mm from the apical root-end and an aspiration needle that was connected to a Root ZX apex locator placed 2 and 3 mm short of the apical root-end in groups 1 and 2, respectively. In the conventional method, the tip of an injection needle used for delivery of the irrigant and as an active electrode was placed 2 and 3 mm short of the apical root-end in groups 3 and 4, respectively, the tip of the aspiration needle was placed 12 mm from the apical root-end in these groups. The readings of the Root ZX during irrigation were recorded. The cleanliness of the canal was evaluated by scoring smear layer from scanning electron microscopy (SEM) images of the canal. Extrusion of NaOCl was detected by measuring the discoloured area of the agar around the apical root-end. The data obtained were statistically analysed by one-way anova, the Kruskal-Wallis test and Friedman's test. RESULTS: In the SEM study, the canals in groups 1-3 were significantly cleaner than those in the control and group 4 (P < 0.05). The mean Root ZX readings in groups 1-3 were approximately "0.5". The discoloured area in group 3 was significantly larger than the other groups (P < 0.05). CONCLUSIONS: Irrigation using the intracanal aspiration technique allowed more effective removal of the smear layer than that performed by the conventional method in an apically resected canine tooth. The intracanal aspiration technique produced limited extrusion of the irrigant beyond the apical foramen.

Apicoectomy↗
PubMed2004

Histological analysis of the cleaning capacity of nickel-titanium rotary instrumentation with ultrasonic irrigation in root canals.

This study evaluated, histologically and morphometrically, the cleaning capacity of rotary instrumentation in root canals using the Profile system with ultrasonic irrigation. Twelve single-rooted mandibular incisors were divided randomly into three groups according to the irrigation method tested. The canals in the teeth were instrumented using Orifice Shapers, taper 0.6 and 0.4 in the cervical third, and up to a #35 file in the apical third. One per cent sodium hypochlorite was used as the irrigating solution. Group I: canals were irrigated with 5 ml of solution, using a Luer-Lok syringe, between each file. Group 2: canals were irrigated with the solution and instrumented using ultrasound for I min between each file. Group 3: canals were irrigated with 5 ml of solution with Luer-Lok syringe, between each file, and final irrigation using ultrasound for 3 min. After chemo-mechanical preparation, the apical thirds of the teeth were submitted for histological processing. Morphometric analysis was performed using an optical microscope with 40x magnification and a grid. The results showed statistical difference at the 5% level between the methods used for irrigation. Rotary instrumentation with Profile system NiTi files and ultrasonic irrigation for 3 min was more effective in cleaning root canals when the different methods were compared.

Dental Alloys↗
PubMed1980

Prospective controlled trial comparing colostomy irrigation with "spontaneous-action" method.

Thirty randomly selected patients with permanent colostomies entered a prospective controlled trial comparing colostomy irrigation with spontaneous action. Each patient was interviewed and examined before irrigation was begun and again after the technique had been used for three months. Each then reverted to spontaneous action for a further three months and was then reassessed. Eight patients abandoned irrigation and 22 (73%) adhered to the protocol. Irrigation caused no mishaps or complications. The mean time spent managing the stoma was 45 +/- SEM 9 min/24 hours during spontaneous action and 53 +/- 9 min/24 hours during irrigation. This difference was not significant. The numbers of bowel actions weekly were 13 +/ SEM 2 during spontaneous action and 6 +/- 1 during irrigation (p < 0.01). Irrigation reduced odour and flatus in 20 patients and enabled 12 out of 18 to stop using drugs and seven to discard their appliance. Irrigation also improved the social life of 18 patients and the working conditions of eight out of 14. These finding show that some patients may not be suitable for irrigation but that for many it is better than the conventional British method of colostomy management. With modern apparatus the technique is safe.

Adolescent↗
PubMed2000

A survey of current wound irrigation practice in head and neck tumour surgery.

OBJECTIVES: To determine the frequency of use of irrigation amongst head and neck surgeons in the U.K. and Ireland, the range of fluids in use; to identify differences in practice in benign and malignant surgery, and ascertain common theories about irrigation, wound infection and tumour recurrence. METHOD: A postal survey of 695 members of the B.A.O.L. Head and Neck Surgeons (348/695 returned). Eight questions with tick box replies and space for free text. Members were asked about their practice of wound irrigation and opinions on its effect(s). Of 348 returned questionnaires 301 were used, 47 discarded as members had retired. RESULTS: 203 of 301 carried out head and neck tumour surgery (67.44%). 67.98% routinely perform wound irrigation. A variety of fluids are used, the most common being sterile water, then saline (table II). Reducing wound infection and tumour recurrence were reasons for irrigating by 47.1%, reducing infection alone, 15.22%, and reducing tumour recurrence alone, 31.16%. 59.42% believe that irrigation prevents wound seeding by benign tumour cells, 70.29% by malignant cells. Irrigation was performed by 70% of surgeons who did more than 5 head and neck tumour procedures per year and by 56% of surgeons who did less than five. CONCLUSIONS: There is little evidence for the putative effects of wound irrigation as noted from literature. Most studies have been performed on animals. There is a need for further research into wound irrigation, types of fluid used and its effects on head and neck cancer patients.

Head and Neck Neoplasms↗
PubMed2006

Effect of antioxidant on coronal seal of dentin following sodium-hypochlorite and hydrogen-peroxide irrigation.

PURPOSE: To reduce the microleakage of a self-etching priming dentin adhesive with the use of antioxidant or bur finishing after sodium-hypochlorite or hydrogen-peroxide irrigation. METHODS: 70 single-root canals were enlarged and seven different treatment protocols were applied throughout the root canal treatment: The roots in Groups 1, 2, and 3 were irrigated with sodium-hypochlorite. Group 1 was used as the negative control with only sodium-hypochlorite irrigation whereas in Group 2, sodium-ascorbate was applied as an additional irrigation agent following sodium-hypochlorite. Irrigation procedure in Group 3 was same as in Group 1, however, after the roots in this group were obturated, cavities were cleaned off with a carbide bur (bur-finishing) to remove the effect of sodium-hypochlorite. Hydrogen-peroxide irrigation was used in Groups 4, 5 and 6; the procedural steps were similar to those of Groups 1, 2 and 3: hydrogen-peroxide in Group 4, sodium-ascorbate application in Group 5, and bur-finishing in Group 6. Group 7 was the positive control with saline irrigation alone. All roots were obturated with Diaket sealer and gutta-percha cones using cold lateral condensation technique immediately after irrigation. A self-etching priming adhesive plus resin composite was applied after the endodontic treatment. The microleakage of dentin margins was determined using dye-penetration technique with clearing process. RESULTS: The Kruskal-Wallis followed by Mann-Whitney test showed that both sodium-hypochlorite and hydrogen-peroxide deteriorated the marginal seal of the dentin adhesive (P < 0.05), however, following both irrigation solutions the use of sodium-ascorbate reduced the microleakage (P < 0.05). Additionally, when sodium-ascorbate or bur-finishing was applied to remove the deterioration caused by sodium-hypochlorite or hydrogen-peroxide, the microleakage scores obtained were not different from that of the positive control (P > 0.05).

Antioxidants↗
PubMed1986

Response of the canine corneal endothelium to intraocular irrigation with saline solution, balanced salt solution, and balanced salt solution with glutathione.

The right or left anterior chamber of 12 dogs (ie, 24 eyes) was irrigated with 100 ml of 0.9% saline solution, balanced salt solution, or balanced salt solution with glutathione (8 eyes/solution) for 22 minutes. Changes in endothelial cell density and corneal thickness from pretreatment values were evaluated immediately after, and at 2 and 7 days after irrigation. Using specular microscopy and scanning and transmission electron microscopy, corneas were examined immediately after and at 2, 7, and 14 days after irrigation. Changes were not seen in endothelial cell density after irrigation with any of the solutions evaluated. Corneal thickness increased 4% immediately after irrigation with 0.9% saline solution and returned to normal by 1 week after irrigation; treatment with 0.9% saline solution was not associated with visible corneal edema. Ultrastructural changes attributable to differences in irrigating solution composition were not observed. The difference between the endothelium's response to limited irrigation with saline solution, balanced salt solution, and balanced salt solution with glutathione was small and irrigation with these solutions was not associated with permanent endothelial damage.

Acetates↗
PubMed1983

Irrigation of the peritoneal cavity and local antibiotics in the treatment of peritonitis.

Peritonitis was induced in the Sprague-Dawley rats by the implantation of gelatin capsules containing 0.3 milliliter of human fecal suspension into the peritoneal cavity. The rats were then treated with systemic antibiotics or peritoneal irrigation with normal saline solution alone or cephalotin solution, 2,000 micrograms per liter, or both. The results show that peritoneal irrigation with normal saline solution or with cephalotin alone was ineffective, even though the cephalotin concentration used inhibited the growth of all bacterial species isolated during the free stage of peritonitis in vitro. Systemic antibiotics alone as well as in combination with peritoneal irrigation significantly improved the survival rate, p less than or equal to 0.05 and p less than or equal to 0.02, respectively. However, only systemic antibiotics in combination with peritoneal irrigation resulted in a significant cure rate compared with the control group and the group treated with systemic antibiotics alone, p less than or equal to 0.002. There was no increase in the cure or survival rates when antibiotics were added to the peritoneal irrigation fluid. In the second experiment, seven of ten rats treated with systemic antibiotics survived, but only two rats had no intraperitoneal abscesses at autopsy. Intraperitoneal application of antibiotics did not improve these results: six rats survived, and one rat was cured. We conclude that peritoneal irrigation alone is ineffective in the treatment of peritonitis. The addition of peritoneal irrigation to systemic antibiotic therapy, however, resulted in a significantly increased cure rate. The addition of antibiotics to the irrigant does not further improve the results, and local antibiotics are not more effective than systemic antibiotics. We believe that benefit of peritoneal irrigation is due to its mechanical effect.

Animals↗
PubMed1993

Preoperative skin preparation and intraoperative pelvic irrigation: impact on post-cesarean endometritis and wound infection.

OBJECTIVE: To determine the impact of two skin preparation methods and two techniques of pelvic irrigation on the incidence of post-cesarean endometritis and wound infection in an indigent patient population. METHODS: A randomized study was performed in 100 cesarean patients. Subjects were assigned to one of four groups, involving either standard skin preparation (povidone-iodine [7.5%] scrub followed by povidone-iodine [10%] solution) or special skin preparation (5-minute scrub with parachlorometaxylenol followed by povidone scrub and solution), and either normal saline or antibiotic (cefazolin sodium, 1 g in 500 mL normal saline) irrigation of the pelvis and subcutaneous tissue at uterine and fascial closure. Four groups of patients were formed: standard skin preparation plus normal saline irrigation, standard preparation plus antibiotic irrigation, special preparation plus normal saline irrigation, and special preparation plus antibiotic irrigation. RESULTS: Endometritis occurred significantly more often in the combined groups that did not include antibiotic irrigation than in the combined groups involving antibiotic irrigation (P < .001). In contrast, comparison of skin preparation methods between povidone-iodine alone versus preparation including parachlorometaxylenol indicated no significant difference (P = .22). CONCLUSION: Skin preparation with an antibacterial scrub in addition to standard povidone-iodine scrub and solution does not appear to play as significant a role in the reduction of post-cesarean endometritis or wound infection as does intraoperative pelvic irrigation with antibiotic solution.

Adult↗
PubMed1993

Natural establishment and selenium accumulation of herbaceous plant species in soils with elevated concentrations of selenium and salinity under irrigation and tillage practices.

The effects of irrigation and tillage practices were studied on species richness, biomass, and selenium accumulation of naturally established herbaceous plants in soils with elevated levels of selenium (Se) and salinity at Kesterson Reservoir, Merced County, California. The four different irrigation-tillage practice combinations were (1) no irrigation, no tillage; (2) irrigation, no tillage; (3) no irrigation, tillage; and (4) irrigation, tillage. The fields were allowed to become colonized naturally by herbaceous plant species. For the Mediterranean climate in the study site, irrigation was conducted biweekly through the summer months, and tillage was done in 3-month intervals. Biomass and Se accumulation of Atriplex patula L, Bassia hyssopifolia Kuntze, Rev. Gen. Pl., Melilotus indica (L.) All., and Salsola kali L. were substantially affected by irrigation. The degree and direction of the effects were found to be species dependent. The field plots which were tilled at 3-month intervals remained bare throughout the experiment. The total soil Se concentrations in the top 15 cm soil horizon were found to be in the range of 40 to 70 mg kg-1 dry wt. Soil Se concentrations below 25 cm soil depth were much lower and within a range of 2 to 4 mg kg-1. Less than 1/10th of the total soil Se inventory in the top soil horizon was water extractable, and the distribution of the Se inventory did not change significantly over the period of 1990 and 1991 despite the irrigation and tillage practices suggesting that a large portion of the Se inventory was not remobilized. The water-extractable soil Se concentration was found to be significantly lower in soils with the greatest biomass production suggesting an effective bioextraction of soil selenium by the native herbaceous plants.

Agriculture↗
PubMed1996

Accumulation of Cr, Pb, Cu, Ni, Zn and Cd in soil following irrigation with treated urban effluent in Australia.

The effect of irrigation with secondary treated municipal effluent on the accumulation of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) was investigated by monitoring sites that had been irrigated with effluent for 4 and 17 years. At Wodonga, seven tree species were sprinkler irrigated with effluent at an average application rate of 1347 mm per annum from 1980 to 1984. The other site at Canberra was a large grass playing field (9 ha), half of which had been effluent irrigated since 1977. The non-effluent irrigated area served as the control area and provided reference 'background' concentration to assess the extent of contamination due to 17 years of effluent irrigation. Archived soil samples collected before the commencement of effluent irrigation were compared with those taken in 1984 at Wodonga to assess the extent of contamination. The concentration of labile metals was determined by extraction with EDTA because this method provides a quantitative measure of bioavailable metals. Irrigation with effluent did not increase the EDTA-extractable metals concentration at either site. Furthermore, the EDTA-extractable metal values were within the natural 'back-ground' range reported for Australian soils. These data suggest that it may take between 50 and 100 years for heavy metal levels (mainly Cd) in effluent-irrigated soil to reach the currently proposed threshold values for environmental concern. The potentially harmful effects of long-term accumulation of heavy metals on plant growth cannot be ignored and could affect the sustainability of land-based disposal of effluent.

Journal Article↗
PubMedDate not supplied

Ecology of cycloheximide-resistant fungi in field soils receiving raw city wastewater or normal irrigation water.

The effect of raw city wastewater irrigation on biodiversity and population densities of a cycloheximide-resistant (CH) fungal community was studied in 13 field soils receiving either raw city wastewater or normal irrigation, and in raw city wastewater in the Nablus area, using the hair baiting technique (HBT) and a surface soil dilution plating (SSDP) technique. Three of these fields [one had been receiving raw city wastewater for more than ten years and was designated a heavily polluted field, and the other 2 were cultivated for the first time and were either irrigated with raw city wastewater (newly polluted field) or normal irrigation water (nonpolluted)], were sampled 4-7 times over a 9-month period. The other ten fields, which had been under raw city wastewater irrigation for more than 10 years, were sampled only once. Fifty-seven CH-resistant species belonging to 18 genera were recovered, of which 49 species were recovered from soil habitats and 28 species from raw city wastewater. The HBT had shown to be more efficient in the isolation of pathogenic and potentially pathogenic fungi including dermatophytes. A higher percentage of this group of fungi was recovered from the three main field soils studied using HBT (70% of all isolates), than the SSDP (35.5%); no dermatophytes were recovered by the SSDP method. Two dermatophytes (Microsporum gypseum, and Trichophyton ajelloi), and five more fungi (Arthroderma cuniculi, A. curreyi, Chrysosporium keratinophilum, C. tropicum, C. pannorum), were recovered from these habitats. Wastewater irrigation seemed to have affected the fungal population densities, with the highest population densities being found in the heavily polluted field soil, while lower population densities were found in the nonpolluted field soil. Increases in organic matter were also observed as a result of sewage effluent irrigation. However, basic similarities in the biodiversity of CH-resistant fungal communities existed in nonpolluted and polluted field soils, and raw city wastewater. Comparable numbers of fungal species were recovered from the three main field soils. The species most commonly found in those habitats included: Alternaria alternata, Aspergillus candidus, Geotrichum candidum, and Paecilomyces lilacinus. Field soils receiving either raw city wastewater or normal irrigation water, were found to be rich in pathogenic and potentially pathogenic CH-resistant fungi, including dermatophytes, with raw city wastewater yielding the highest percentage (81%), followed by the newly wastewater irrigated field (77.7%), the nonpolluted field (67%), and the heavily polluted field (63.4%) Hygienic measures should therefore be taken to control the spread of these fungi in the environment of human communities, and to avoid mycotic infections among farmers.

Agriculture↗