Assessment of nitrification in groundwater filters for drinking water production by qPCR and activity measurement

In groundwater treatment for drinking water production, the causes of nitrification problems and the effectiveness of process optimization in rapid sand filters are often not clear. To assess both issues, the performance of a full-scale groundwater filter with nitrification problems and another filter with complete nitrification and pretreatment by subsurface aeration was monitored over nine months. Quantitative real-time polymerase chain reaction (qPCR) targeting the amoA gene of bacteria and archaea and activity measurements of ammonia oxidation were used to regularly evaluate water and filter sand samples. Results demonstrated that subsurface aeration stimulated the growth of ammonia-oxidizing prokaryotes (AOP) in the aquifer. Cell balances, using qPCR counts of AOP for each filter, showed that the inoculated AOP numbers from the aquifer were marginal compared with AOP numbers detected in the filter. Excessive washout of AOP was not observed and did not cause the nitrification problems. Ammonia-oxidizing archaea grew in both filters, but only in low numbers compared to bacteria. The cell-specific nitrification rate in the sand and backwash water samples was high for the subsurface aerated filter, but systematically much lower for the filter with nitrification problems. From this, we conclude that incomplete nitrification was caused by nutrient limitation.     

Analysis and jointing of polygonal road slabs

Conclusions 1. For anlaysis of circular (polygona) slabs which can be included in the category of absolutely rigid slabs, a practical approximate method of analysis has been developed and experimentally verified which permits determining the bending moments under centrally and eccentrically applied loads acting over a small circular area, as well as at any other points in the slab beyond the limits of the loaded area.2. Monolithic bonding of hexagonal road slabs up to 3–4 m² in area designed for the N-30 load results in increased design bending moments and, consequently, in thicker pavements. For these slabs it is expedient to use nonrigid joints, which do not transmit bending or torsional moments; however, these slabs must be placed on stabilized beds and their joints must be filled with waterproofing mastic.Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, pp. 19–22, September–October, 1974.     

Lead,cadmium, and arsenic residues in animal tissues in relation to those in their surrounding habitat

The relationships of the residues of lead, cadmium, and arsenic in animal tissues to those in surrounding vegetation and soil were determined in a natural habitat representing a wide range of such residues. The samples studied were selected from 18 different locations. Analyses were performed on a total of 113 animals, 332 plant specimens (representing 33 species), and 408 soil samples (taken at different depths). For the purpose of evaluating relationships, the samples from each location were averaged and reported as parts per million on a dry weight basis. The average lead residues from different locations ranged from 1.4–9.2 ppm in the liver, 45–195 in bones, 4–283 in vegetation, and 15–1399 in soil samples. The cadmium contents ranged from 1–27 ppm in the liver, 3–77 in bones, 0.5–5 in vegetation, and 1–10 in soil. The arsenic contents in different components of the ecosystem varied with an average of 1–9 ppm in liver, 0.6–94 in vegetation, and 7–655 in soil samples. The soil residues varied considerably according to the depth of sampling. Little variation was noted in different species of vegetation or in soil and vegetation samples according to the time and year of sampling.Statistical analyses performed on the averages indicated a significant correlation between vegetation and soil residues for all three elements, and also between animal to vegetation and animal to soil cadmium residues. Multiple linear correlations for all elements in soil, vegetation, and animal tissues were determined. The results indicated a possibility of an increase in cadmium in animal tissues depending upon the increased residues of this metal in the environment.     

Paleonutritional analysis of the pre-Hispanic population from Fuerteventura (Canary Islands)

In this study, from histological and chemical perspectives, we analyse the human remains belonging to the pre-Hispanic inhabitants from Fuerteventura (one of the Canary Islands) and compare the results with those obtained on a sample of pre-Hispanic inhabitants from Gran Canaria (Canary Islands). We observe that trabecular bone mass was normal in the samples from Fuerteventura except for an elderly woman; this result is in sharp contrast with the decreased bone mass observed in the population from Gran Canaria. The pre-Hispanic population from Fuerteventura showed lower bone strontium, Sr/Ca ratio, and bone barium, but slightly higher bone copper, than that from Gran Canaria. All these data indicate a greater consumption of marine products by the population of Fuerteventura. The high prevalence of osteoporosis observed in the population from Gran Canaria may be interpreted as a consequence of protein-calorie malnutrition, a condition which seemed to be not so prevalent in the population of Fuerteventura.     

A method for the analysis of environmental factors controlling patterns of species composition in aquatic communities

In aquatic environmental studies, data from biological samples and from associated observations on environmental variables are often analyzed to determine whether environmental factors are controlling patterns of species composition. Analysis methods which reduce biological data such as species abundances to a more useable form, including ordination, classification and diversity index methods, are critically reviewed. Methods which relate these reduced data to environmental data are also reviewed. Classification (or cluster) analysis of the biological data followed by multiple discriminant analysis of the species-assemblage groups on the environmental variables is the recommended procedure, which is illustrated by an example. Application of these methods to pollution studies is discussed. Possible modifications and extensions are considered.     

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.     

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.