The direct measurement of ppm levels of uranium in soils using high-resolution Ge(Li) gamma-ray spectroscopy

The direct determination of ²³⁸U in various soil samples was done by measuring the 63.3-keV transition from the decay of the first daughter ²³⁴Th. Potential errors resulting from the chemical non-equilibrium of ²³⁸U with its daughters are thus avoided. The method sensitivity is 1 ppm compared to the 35 ppm obtainable by employing the 1001-keV gamma ray. A Ge(Li) gamma-ray spectrometer is the only analytical tool required. Examples are offered that demonstrate the usefulness of the technique for routine, inexpensive environmental monitoring of uranium. The technique also has the capability of providing information on the ²³⁸U/²³⁵U isotopic ratio.     

Heavy metals in tissues of stranded short-finned pilot whales.

Selected tissues from four short-finned pilot whales that stranded at Cumberland Island National Seashore were analyzed for total cadmium, mercury and selenium by neutron activation. Cadmium reached a maximum mean wet weight concentration of 31.4 ppm in the kidney tissues. Maximum mean wet weight concentrations of mercury, 230.0 ppm, and selenium, 44.2 ppm, were found in the liver tissues. The lowest concentration of each metal was found in the blubber. Postmortem examination showed that the whales had no food in their stomachs. The whales must have been utilizing metabolic reserves, contaminated with residual concentrations of heavy metals, prior to beaching. This utilization of reserves probably resulted in the high concentrations of cadmium, mercury and selenium found in the liver and kidney tissues. Since the heavy metal concentrations were three to four times greater in the stranded whales, as compared to apparently healthy whales of the same species, it is suggested that heavy metal toxicosis may have been a factor contributing to this particular stranding.     

Online Documentation for Engineering Software: A Hypertext Application

Abstract: This article describes the use of 'hypertext' as a means to document engineering software online. An extensive hypertext document can be built with relative ease using an authoring tool. Hypertext documents enhance the learning process through the association of facts. The user has the freedom to arrange his/her own study sequence in a particular session. The article provides a brief introduction to the hypertext technology and authoring tools, and describes a Mohr's Circle program, which has been developed to explore the use of hypertext for online users' manuals. The strengths and weaknesses of the software tool, KnowledgePro, as well as the development techniques, are discussed.     

Hybrid reactor for priority pollutant-trichloroethylene removal

The present study was initiated to explore the potential of a hybrid biological reactor, combining trickling filter (TF) and activated sludge process (ASP), to treat wastewater containing trichloroethylene (TCE) at ambient temperature at different hydraulic retention time (HRT). The biofilm acclimation was achieved in 55-60 days with gradual increase in TCE concentration from 1 mg/l to 100 mg/l with a parallel increase in the concentration of substrate sodium acetate and other nutrients. COD and TCE concentration were taken as prime parameters for monitoring the growth of biofilm. During acclimation COD removal varied between 54.6-97.5% while TCE was removed 72.6-99.9%. HRT study was performed after acclimation. The removal efficiency increased with decreasing flow rate with maximum TCE removal (99.99%) at 6 l/d corresponding to an HRT of 28 h (TF 18 h + ASP 10 h). This was followed by a C:N:P ratio study. A ratio of 100:20:1 led to the sustenance of maximum TCE removal. Maximum TCE removal (99.99%) was observed at a substrate:cosubstrate ratio of 100:1. A pH of 7.4 +/- 0.2 was found to be optimum for degradation. Finally, volatilization losses were estimated to be 18.5%. A mass balance gave an efficiency of 81.51% for biological removal of TCE.     

Sulfolane biodegradation potential in aquifer sediments at sour natural gas plant sites

Sulfolane is used in the treatment of sour natural gas. It is a highly water soluble compound that has been introduced into soils and groundwaters at a number of sour gas processing plant sites. Aquifer sediments from contaminated locations at three sites in western Canada were assessed for microbial activity and their ability to degrade sulfolane under aerobic and five anaerobic (nitrate-, Mn(IV)-, Fe(III)-, sulfate- and CO₂-reducing) conditions. The microcosms were supplemented with 200 mg/L sulfolane and adequate supplies of N, P, and the appropriate terminal electron acceptor. Microcosms containing contaminated aquifer sediments from each of the three sites were able to degrade sulfolane aerobically at 8°C and 28°C, and the biodegradation followed zero-order kinetics. The lag times before the onset of sulfolane biodegradation were shorter when sulfolane-contaminated sediments were used as inocula than when uncontaminated soils were used. No anaerobic sulfolane biodegradation was observed at 28°C, nor was sulfolane biodegradation observed at 8°C under Fe(III)-, sulfate- and CO₂-reducing conditions. At 8°C, anaerobic degradation of sulfolane coupled to Mn(IV) reduction was observed in microcosms from two sites, and degradation coupled to nitrate reduction was seen in a microcosm from one of the contaminated sites.     

The manual determination of ammonia in fresh waters using an ammonia-sensitive membrane-electrode

The use of a commercially-available ammonia-sensitive membrane-electrode for the manual determination of ammonia in discrete samples of fresh water has been investigated and the analytical procedure is described. The electrode is simple and convenient to use, and a sample can be analyzed in a few minutes. For normal routine analysis, the lower limit of determination is approximately 0·1 mg N 1⁻¹ though smaller concentrations can be measured. The relative standard deviation of analytical results varied from approximately 10 to 3 per cent as ammonia concentration increased from 0·1 to 4 mg N 1⁻¹. Results for samples of river water agreed well with those obtained by absorptiometric methods of analysis; the electrode responds to amines but otherwise appears to be essentially specific for ammonia. Use of the electrode will be advantageous in a number of applications, and it also has good potential for the on-line analysis of fresh waters.     

Treatment of poultry manure wastewater using a rotating biological contactor

A pilot scale, six stage rotating biological contactor was used to evaluate the feasibility of this process for the stabilization of liquid animal manures. Total disc surface area was approx. 16.7 m². Treatment efficiencies were determined at various waste strengths and influent flow rates.With loading rates of 14.7–322 g m⁻² day⁻¹, the average COD reduction was 61%. With loading rates of 4.88-24.4 g m⁻² day⁻¹, the average BOD₅ reduction was 87%. Total nitrogen removal averaged approximately 30% for the entire study. Mixed liquor oxygen uptake rates were generally in excess of 80 mg 1⁻¹ h⁻¹.Clarified effluent was non-odorous and suitable to be reused for manure flushing or spray irrigation. Treatment was not sufficient to permit effluent discharge to surface waters.     

Assessment of environmental tobacco smoke exposure: urinary cotinine concentrations in children are strongly associated with the house dust concentrations of nicotine at home

In the present study the possibility of using nicotine in house dust as an index of environmental tobacco smoke (ETS) exposure was evaluated in an environmental investigation of 23 children with asthma. A standardized procedure for house dust sampling of nicotine with a filter holder connected to a vacuum cleaner, for a defined time and area was developed (F-nicotine). Also, house dust sampling was carried out from the vacuum cleaner bags of the homes (VC-nicotine). There was a larger variation in VC-nicotine (13-655, median 66 microg/g) compared with F-nicotine (15-393 median 156 microg/g). There were statistically significant associations between an inquiry data based ETS exposure index on the one hand, and urinary cotinine concentrations in children (U-cotinine), F-nicotine and VC-nicotine of their homes, on the other. The strong correlation between U-cotinine and F-nicotine (rs = 0.93; P < 0.0001) indicates that the new standardized house dust sampling method should be useful in ETS exposure assessment. However, further validation by a larger sample size with repeated measurements in the same homes is needed.