An evaluation of septic tank effluent movement in soil and groundwater systems

Recent studies have shown that septic tank systems are a major source of groundwater pollution. Many public health workers feel that the most cri^cal aspect of the use of septic tanks as a means of sewage disposal is the contamination of private water wells with attendant human health hazards. In this study the movement and attenuation of septic tank effluents in a range of soil/overburden types and hydrogeological situations was investigated. The suitability of a number of chemical and biological tracer materials to monitor the movement of septic tank effluent constituents to groundwater sources was also examined. The investigation was divided into three separate but inteiTelated sections. In the first section of the study the movement of septic tank effluent from two soil treatment systems was investigated by direct measurements of soil nutrient concentrations and enteric bacterial numbers in the soil beneath and downgradient of the test systems. Two sites with different soil types and hydrogeological characteristics were used. The results indicated that the attenuation of the effluent in both of the treatment systems was incomplete. Migration of nitrate, ammonium, phosphate and fecal bacteria to a depth of 50 cm beneath the inverts of the distribution tiles was demonstrated on all sampling occasions. The lateral migration of the pollutants was less pronounced, although on occasions high nutrients levels and fecal bacterial numbers were detected at a lateral distance of 4.0 m downgradient of the test systems. There was evidence that the degree and extent of effluent migration was increased after periods of heavy or prolonged rainfall when the attenuating properties of the treatment systems were reduced as a result of saturation of the soil. The second part of the study examined the contamination of groundwaters downgradient of septic tank soil treatment systems. Three test sites were used in the investigation. The sites were chosen because of differences in the thicknesses and nature of the unsaturated zone available for effluent attenuation at each of the locations. A series of groundwater monitoring boreholes were installed downgradient of the test systems at each of the sites and these were sampled regularly to assess the efficiency of the overburden material in reducing the polluting potential of the wastewater. Effluent attenuation in the septic tank treatment systems was shown to be incomplete, resulting in chemical and microbiological contamination of the groundwaters downgradient of the systems. The nature and severity of groundwater contamination was dependent on the composition and thickness of the unsaturated zone and the extent of weathering in the underlying saturated bedrock. The movement of septic tank effluent through soil/overburdens to groundwater sources was investigated by adding a range of chemical and biological tracer materials to the three septic tank systems used in section two of the study. The results demonstrated that a single tracer type cannot be used to accurately monitor the movement of all effluent constituents through soils to groundwater. The combined use of lithium bromide and endospores of Bacillus globigii was found to give an accurate indication of the movement of both the chemical and biological effluent constituents.

Transfer of radionuclides from soil to vegetation in selected Irish ecosystems

This thesis details the findings of a study relating the transfer of 238U, 228Ra (232Th), 226Ra, and 137Cs from soil to vegetation in an Atlantic blanket bog, upland blanket bog and semi-natural grassland situated along the north-west coast of Ireland. The results of this study provide information on the uptake of these radionuclides by the indigenous vegetation found present in these ecosystems. The ecosystems chosen are internationally recognizable ecosystems and provide a wide variety of vegetation species and contrasting soil physiochemical properties which allow the influence of these parameters on radionuclide uptake to be assessed. The levels of radionuclides in the soil and vegetation were measured using gamma spectrometry, alpha spectrometry and ICP-MS. The nutrient status of the vegetation and soil physiochemical properties were measured using atomic absorption, flame photometry and other analytical techniques. The results of the study indicate that the uptake of 238U and 228Ra (232Th) by vegetation from all three ecosystems was negligible as the levels in all vegetation was below the limits of detection for the methods used in this study. These results appear to indicate that the vegetation studied do not possess the ability to accumulate significant levels of these radionuclides however this assumption cannot be upheld in the case of the Atlantic blanket bog as the levels in the soil of this ecosystem were too low for detection. Similar results were obtained for 226Ra uptake in both the Atlantic blanket bog and grassland for all vegetation with the exception of H. lanatus from the grassland ecosystem. Radium-226 uptake in upland blanket bog was higher and was detectable in the majority of vegetation indigenous to this ecosystem. Transfer factor values ranged from 0.07 to 2.35 and the TF values for E. tetralix were significantly higher than all other vegetation studied. This species of heather demonstrated the ability to accumulate 226Ra to a greater extent than all other vegetation. The uptake of 226Ra by upland blanket bog vegetation appears to be significantly influenced by a range of soil physiochemical properties. The nutrient status of the vegetation, in particular the calcium content in the vegetation appears to have a negative impact on the uptake of this radionuclide. Potassium-40 was detectable in all vegetation present in the three ecosystems and the levels in the grassland soil were significantly higher than the levels in both bogland soils. Transfer factor values for Atlantic blanket bog vegetation ranged from 0.9 to 13 .8 and were significantly higher in E. vaginatum in comparison to C. vulgaris. Potassium-40 TF values for upland blanket bog vegetation on average ranged from 1.4 for C. vulgaris (stems) to 5.2 for E. vaginatum and were statistically similar for all species of vegetation. Transfer factor values for grassland vegetation ranged from 0.7 to 3.8 and were also statistically similar for all species of vegetation indicating that the transfer of 40K to vegetation within the upland bog and grassland ecosystem is not dependent on plant species. Comparisons of 40K TF values for all three ecosystems indicate that the uptake in E. vaginatum from the Atlantic blanket bog was statistically higher than all other vegetation studied. This appears to indicate that E. vaginatum has the ability to accumulate 40K, however, this species of vegetation was also present in the upland blanket and did not demonstrate the same behaviour. The uptake of 40K by vegetation from all three ecosystems was significantly affected by a range of soil physiochemical properties and in some cases the results were contradictory in nature possibly indicating that the affect of these parameters on 40K uptake is species dependent. The most obvious trend in the data was the influence of soil CEC and magnesium levels in vegetation on 40K TF values. A positive correlation was apparent between the CEC of the soil and 40K uptake in vegetation from both the Atlantic blanket bog and grassland ecosystem. A similar trend was apparent between magnesium levels in vegetation and 40K TF values for the upland blanket bog and grassland vegetation. Caesium-13 7 levels were found to be significantly higher in the two bogland soils in comparison to the grassland soil and levels of 137Cs decreased with increasing soil depth. Transfer factor values for Atlantic blanket bog vegetation ranged from 1.9 to 9.6 and TF values were significantly higher in the leaves o f C. vulgaris in comparison to all other vegetation from this ecosystem. Caesium-13 7 TF values for the upland blanket bog vegetation on average ranged from 0.29 for E. tetralix to 1.6 for C. vulgaris. Uptake by the leaves of C. vulgaris was significantly higher than all other vegetation present thereby supporting the trend found within the Atlantic blanket bog vegetation. These results appear to indicate that the leaves of C. vulgaris have the ability to accumulate significant quantities of 137Cs and also that the uptake of 137Cs by this vegetation is dependent on plant compartment as the stems of this vegetation contained significantly lower levels than the leaves in both ecosystems. The uptake of 137Cs by grassland vegetation was very low and was only detectable in a fraction of the vegetation sampled. Caesium-137 TF values for grassland vegetation were in general lower than 0.02. The impact of soil physiochemical properties and nutrient status of vegetation on 137Cs uptake by vegetation appears to be complex and in some cases contradictory. The most apparent trend in the data was the positive influence of vegetation nutrients on 137Cs uptake in particular the magnesium levels present in the vegetation and to a lesser extent the calcium levels present. The results in general indicate that the uptake of 226Ra, 40K and 137Cs by the chosen vegetation is varied and complex and is significantly dependent on the species of vegetation, soil radionuclide concentration, soil physiochemical properties and the nutrient status of the vegetation.

The spatial analysis and speciation of uranium and thorium series radionuclides in the soil of the Cronamuck Valley, County Donegal, Ireland

This thesis details the findings of a study into the spatial distribution and speciation of 238U, 226Ra and 228Ra in the soils of the Cronamuck valley, County Donegal . The region lies on the north-eastern edge of the Barnesmore granite and has been the subject of uranium prospecting efforts in the past. The results of the project provide information on the practicability of geostatistical techniques as a means of estimating the spatial distribution of natural radionuclides and provide insight into the behaviour of these nuclides and their modes of occurrence and enrichment in an upland bog environment. The results of the geostatistical survey conducted on the area indicate that the primary control over the levels of the studied nuclides in the soil of the valley is the underlying geology. Isopleth maps of nuclide levels in the valley indicate a predominance of elevated nuclide levels in the samples drawn from the granite region, statistical analysis of the data indicating that levels of the nuclides in samples drawn from the granite are greater than levels drawn from the non-granite region by up to a factor of 4.6 for 238U and 4.9 for 226Ra. Redistribution of the nuclides occurs via drainage systems within the valley, this process being responsible for transport of nuclides away from the granite region resulting in enrichment of nuclides in soils not underlain by the granite. Distribution of the nuclides within the valley is erratic, the effect of drainage f lows on the nuclides resulting in localized enriched areas within the valley. Speciation of the nuclides within one of the enriched areas encountered in the study indicates that enrichment is as a result of saturation of the soil with drainage water containing trace amounts of radionuclides. 238U is primarily held within the labile fractions (exchangeable cat ions + easily oxidisable organics + amorphous iron oxides ) of the soil , 226Ra being associated with the non- labile fractions, most probably the resistant organic material. 228Ra displays a significant occurrence in both the labile and non- labile fractions. The ability of the soil to retain uranium appears to be affected largely by the redox status of the soil, samples drawn from oxidizing environments tending to have little or no uranium in the easily oxidisable and amorphous iron oxide fractions. This loss of uranium from oxidised soil samples is responsible for the elevated 226Ra /238U disequilibrium encountered in the enriched areas of the valley. Analysis of the data indicates that samples displaying elevated 226Ra/238U ratios also exhibit elevated 228Ra/238U ratios indicating a loss of uranium from the samples as opposed to an enrichment of 226Ra.

Process of fixation, imobilization and mineralization of ammonium in soil using N-15

The organic and inorganic forms of soil nitrogen and how they participate in the process of fixation, immobilization and mineralization of ammonium in soils were evaluated, after different periods of incubaton, utilizing two soils, a Lithic Haplustoll and a Typic Eutrorthox. The results obtained permit to suggest that : 1) The method for determination of the ammonium fixing capacity based on the extraction with 2N KC1, is considered to be subject to interferences of other soil fractions capable of retaining ammonium. 2) The increase in exchangeable ammonium content is related to the decrease in amino acids and hydrolyzable ammonium. 3) The immobilization and mineralization processes are still held under mil microbial. The forms more affected by this condition are amino acids and hydrolyzable ammonium.

Doses and methods of distribution of potassium chloride on soybean crop (Glycine max (L.) Merrill) in a red latosol, affecting soil salinity, grain production and chemical composition of leaves

The present work deal t wi th an experiment under field conditions and a laboratory test of soil incubation the objectives were as follows: a. to study effects on soybean grain product ion and leaf composition of increasing doses of potassium chloride applied into the soil through two methods of distribution; b. to observe chemical modifications in the soils incubated with increasing doses of potassium chloride; and, c. to correlate field effects with chemical alterations observed in the incubation test, The field experiment was carried out in a Red Latosol (Haplustox) with soybean cultivar UFV - 1. Potassium chloride was distributed through two methods: banded (5 cm below and 5 cm aside of the seed line) and broadcasted and plowed-down. Doses used were: 0; 50; 100 and 200 kg/ha of K2O. Foliar samples were taken at flowering stage. Incubation test were made in plastic bags with 2 kg of air dried fine soil, taken from the arable layer of the field experiment, with the following doses of KC1 p,a. : 0; 50; 100; 200; 400; 800; 1,600; 3.200; 6,400 and 12,800 kg/ha of K(2)0. In the conditions observed during the present work, results allowed the following conclusions: A response by soybean grain production for doses of potassium chloride, applied in both ways, banded or broadcasted, was not observed. Leaf analysis did not show treatment influence over the leaf contents for N, P, K, Ca, Mg, and CI, Potassium chloride salinity effects in both methods of distribution for all the tested closes were not observed.

Increasing the efficiency of utilization of soil and fertilizer phosphorus in the subtropical and tropical agricultural systems C

As a rule, soils of the subtropical and tropical regions, in which rainfall is not limiting, are acidic, and low in phosphorus, and, to a less extent, in other macro and micronutrients as well, such a sulfur, boron and zinc. The establishment of a permanent agricultural prac. tice therefore, demands relatively high usage of liming and phosphatic fertilization, to begin with. Several approaches, not mutually exclusive, could be used in order to increase the efficiency of utilization of soil and fertilizer phosphorus so that, goal of diminishing costs of production is reached. The use of liming materials bringing up pH to 6.0-6.5 causes the conversion of iron and aluminum phosphates to more available calcium phosphates; on the other hand, by raising calcium saturation in the exchange complex, it improves the development and operation if the root system which allows c or a higher utilization of all soil nutrients, including phosphorus, and helps of stand water deficits which may occur. The role of mycorrhizal fungi should be considered as a way of increasing soil and fertilizer P utilization, as well as the limitations thereof. Screening of and breeding for varieties with higher efficiency of uptake and utilization of soil and fertilizer phosphorus leads to a reduction in cost of inputs and to higher benefit/cost ratios. Corrective fertilization using ground rock phosphate helps to saturate the fixation power of the soil thereby reducing, as a consequence, the need for phosphorus in the maintenance fertilization. Maintenance fertilization, in which soluble phos-phatic sources are used, could be improved by several means whose performance has been proved: limimg, granula tion, placement, use of magnesium salts. Last, cost of phosphate fertilization could be further reduced, without impairing yields, through impairing yields, through changes in technology designed to obtain products better adapted to local conditions and to the availability or raw materials and energy sources.

Soil invertebrates in southern Brazilian Araucaria forest - grassland mosaic: differences between disturbed and undisturbed areas

Soil invertebrate distribution in Araucaria forest, grassland and edge habitats was studied in both disturbed and undisturbed areas in southern Brazil. Mean-density and taxa compositions were verified. Invertebrate densities differed between grassland and the other two habitats in the undisturbed area but not across the disturbed one. At the disturbed area taxa differed between the grassland and the other two habitats. The undisturbed area, on the other hand, presented taxa differences only between the grassland and the forest habitats. Acari, Arachnida and Collembola were the most sensitive taxa for detecting differences across habitats in both areas. At the disturbed area, these taxa presented densities lowering from the forest to the grassland. At the undisturbed area the same taxa increased from the forest to the grassland. Coleoptera and Formicidae (Insecta) presented no difference between habitats at the studied taxonomic level.

The isolation of the perfect form of Microsporum Gypseum, Nannizzia Gypsea, Stockdale, 1963, from brazilian soil

Our work is on the isolation from brazilian soil of the perfect stage of Microsporum gypseum, Nannizzia gypsea, Stock., 1963, using cut sterilized children hair as bait.

Alleviating abiotic and biotic soil constraints by combining Arbuscular Mycorrhizal Fungi with banana and plantain micropropagation systems

The objectives of Participant 4 were: - Establishment and maintenance of a representative collection of AM fungal species in vivo on trap plant cultures. - Study of the effects of early mycorrhizal inoculation in the growth and health of in vitro plantlets and their subsequent behaviour in the nursery. - Effect of the mycorrhization of in vitro produced bananas and plantains on plant growth and health, under biotic stress conditions (nematode and fungi)

Getting the most sulfate from soil: Regulation of sulfate uptake transporters in Arabidopsis.

Sulfur (S) is an essential macronutrient for all living organisms. Plants require large amounts of sulfate for growth and development, and this serves as a major entry point of sulfate into the food web. Plants acquire S in its ionic form from the soil; they have evolved tightly controlled mechanisms for the regulation of sulfate uptake in response to its external and internal availability. In the model plant Arabidopsis thaliana, the first key step in sulfate uptake is presumed to be carried out exclusively by only two high-affinity sulfate transporters: SULTR1;1 and SULTR1;2. A better understanding of the mode of regulation for these two transporters is crucial because they constitute the first determinative step in balancing sulfate in respect to its supply and demand. Here, we review the recent progress achieved in our comprehension of (i) mechanisms that regulate these two high-affinity sulfate transporters at the transcriptional and post-transcriptional levels, and (ii) their structure-function relationship. Such progress is important to enable biotechnological and agronomic strategies aimed at enhancing sulfate uptake and improving crop yield in S-deficient soils.

Fungi, bacteria and soil pH: the oxalate-carbonate pathway as a model for metabolic interaction

The oxalatecarbonate pathway involves the oxidation of calcium oxalate to low-magnesium calcite and represents a potential long-term terrestrial sink for atmospheric CO2. In this pathway, bacterial oxalate degradation is associated with a strong local alkalinization and subsequent carbonate precipitation. In order to test whether this process occurs in soil, the role of bacteria, fungi and calcium oxalate amendments was studied using microcosms. In a model system with sterile soil amended with laboratory cultures of oxalotrophic bacteria and fungi, the addition of calcium oxalate induced a distinct pH shift and led to the final precipitation of calcite. However, the simultaneous presence of bacteria and fungi was essential to drive this pH shift. Growth of both oxalotrophic bacteria and fungi was confirmed by qPCR on the frc (oxalotrophic bacteria) and 16S rRNA genes, and the quantification of ergosterol (active fungal biomass) respectively. The experiment was replicated in microcosms with non-sterilized soil. In this case, the bacterial and fungal contribution to oxalate degradation was evaluated by treatments with specific biocides (cycloheximide and bronopol). Results showed that the autochthonous microflora oxidized calcium oxalate and induced a significant soil alkalinization. Moreover, data confirmed the results from the model soil showing that bacteria are essentially responsible for the pH shift, but require the presence of fungi for their oxalotrophic activity. The combined results highlight that the interaction between bacteria and fungi is essential to drive metabolic processes in complex environments such as soil.

3D geoelectrical monitoring to follow hydric soil behaviour during rainfall

RESUME Durant les dernières années, les méthodes électriques ont souvent été utilisées pour l'investigation des structures de subsurface. L'imagerie électrique (Electrical Resistivity Tomography, ERT) est une technique de prospection non-invasive et spatialement intégrée. La méthode ERT a subi des améliorations significatives avec le développement de nouveaux algorithmes d'inversion et le perfectionnement des techniques d'acquisition. La technologie multicanale et les ordinateurs de dernière génération permettent la collecte et le traitement de données en quelques heures. Les domaines d'application sont nombreux et divers: géologie et hydrogéologie, génie civil et géotechnique, archéologie et études environnementales. En particulier, les méthodes électriques sont souvent employées dans l'étude hydrologique de la zone vadose. Le but de ce travail est le développement d'un système de monitorage 3D automatique, non- invasif, fiable, peu coûteux, basé sur une technique multicanale et approprié pour suivre les variations de résistivité électrique dans le sous-sol lors d'événements pluvieux. En raison des limitations techniques et afin d'éviter toute perturbation physique dans la subsurface, ce dispositif de mesure emploie une installation non-conventionnelle, où toutes les électrodes de courant sont placées au bord de la zone d'étude. Le dispositif le plus approprié pour suivre les variations verticales et latérales de la résistivité électrique à partir d'une installation permanente a été choisi à l'aide de modélisations numériques. Les résultats démontrent que le dispositif pôle-dipôle offre une meilleure résolution que le dispositif pôle-pôle et plus apte à détecter les variations latérales et verticales de la résistivité électrique, et cela malgré la configuration non-conventionnelle des électrodes. Pour tester l'efficacité du système proposé, des données de terrain ont été collectées sur un site d'étude expérimental. La technique de monitorage utilisée permet de suivre le processus d'infiltration 3D pendant des événements pluvieux. Une bonne corrélation est observée entre les résultats de modélisation numérique et les données de terrain, confirmant par ailleurs que le dispositif pôle-dipôle offre une meilleure résolution que le dispositif pôle-pôle. La nouvelle technique de monitorage 3D de résistivité électrique permet de caractériser les zones d'écoulement préférentiel et de caractériser le rôle de la lithologie et de la pédologie de manière quantitative dans les processus hydrologiques responsables d'écoulement de crue. ABSTRACT During the last years, electrical methods were often used for the investigation of subsurface structures. Electrical resistivity tomography (ERT) has been reported to be a useful non-invasive and spatially integrative prospecting technique. The ERT method provides significant improvements, with the developments of new inversion algorithms, and the increasing efficiency of data collection techniques. Multichannel technology and powerful computers allow collecting and processing resistivity data within few hours. Application domains are numerous and varied: geology and hydrogeology, civil engineering and geotechnics, archaeology and environmental studies. In particular, electrical methods are commonly used in hydrological studies of the vadose zone. The aim of this study was to develop a multichannel, automatic, non-invasive, reliable and inexpensive 3D monitoring system designed to follow electrical resistivity variations in soil during rainfall. Because of technical limitations and in order to not disturb the subsurface, the proposed measurement device uses a non-conventional electrode set-up, where all the current electrodes are located near the edges of the survey grid. Using numerical modelling, the most appropriate arrays were selected to detect vertical and lateral variations of the electrical resistivity in the framework of a permanent surveying installation system. The results show that a pole-dipole array has a better resolution than a pole-pole array and can successfully follow vertical and lateral resistivity variations despite the non-conventional electrode configuration used. Field data are then collected at a test site to assess the efficiency of the proposed monitoring technique. The system allows following the 3D infiltration processes during a rainfall event. A good correlation between the results of numerical modelling and field data results can be observed since the field pole-dipole data give a better resolution image than the pole-pole data. The new device and technique makes it possible to better characterize the zones of preferential flow and to quantify the role of lithology and pedology in flood- generating hydrological processes.