Influence of organic waste type and soil structure on the bacterial filtration rates in unsaturated intact soil columns (original) (raw)
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Geoderma, 2014
Agricultural manures are the source of several pathogenic microorganisms in surface and groundwater that could cause diseases and adversely affect human health. Some strains of E. coli, an indicator microorganism, when transported over and/or through the soils reaching the water resources, cause urinary tract infections, diarrheal diseases, and contribute to infant mortality, fatal renal or neurological complications. To the best of the authors' knowledge, there is no information about the bacterial transport through natural/intact calcareous and gypsiferous soils. In this study, we selected four soil types to investigate the influence of lime and gypsum content on transport and filtration of E. coli released from cow manure during saturated and unsaturated flows. Intact soil columns from Hamadan and Isfahan provinces in Iran were transported to the laboratory. Cow manure was applied to the surface of each column at a rate of 10 Mg ha −1 dry basis. Soil columns were leached up to four pore volumes (PVs) at 20°C. E. coli influent (C o) and effluent (C) concentrations were measured by the platecount method and C o /C values were drawn vs. PV as breakthrough curves (BTCs). Filtration coefficient (λ f), relative adsorption index (S R), and maximum depth of potential contamination (Z max) were calculated as indices of filtration and transport processes. Our results illustrated that contamination of water is possible where flooding irrigation systems occur in the low-lime soil due to low ionic strength and salinity, and greater structural stability. The BTCs showed that preferential pathways are greater in the low-lime soils than in the other studied soils. The presence of the natural lime and gypsum affected solution chemistry, macro and microporosity of the studied soils, which resulted in more bacterial filtration. The soils high in lime and gypsum also had maximum values for λ f and S R , respectively. Minimum Z max was observed in the high-lime soil and its mean was significantly lower than in the three other soils. The Z max was greater in saturated flow conditions than in unsaturated flow conditions. Overall, when a source of E. coli (e.g. cow manure) is applied on a low-lime or gypsum soil, subsurface water contamination would be expected while high-lime and gypsum soils could filter more bacteria. This study showed the effect of natural lime and gypsum on bacterial transportation through intact soils. It is suggested to use techniques such as scanning electron microscope (SEM) and image analysis to present pore-scale information for bacterial movement through calcareous and gypsiferous soils.
Soil and Waste Matrix Affects Spatial Heterogeneity of Bacteria Filtration during Unsaturated Flow
Water, 2015
Discontinuous flows resulting from discrete natural rain events induce temporal and spatial variability in the transport of bacteria from organic waste through soils in which the degree of saturation varies. Transport and continuity of associated pathways are dependent on structure and stability of the soil under conditions of variable moisture and ionic strength of the soil solution. Lysimeters containing undisturbed monoliths of clay, clay loam or sandy loam soils were used to investigate transport and pathway continuity for bacteria and hydrophobic fluorescent microspheres. Biosolids, to which the microspheres were added, were surface applied and followed by serial irrigation events. Microspheres, Escherichia coli, Enterococcus spp., Salmonella spp. and Clostridium perfringens were enumerated in drainage collected from 64 distinct collection areas through funnels installed in a grid pattern at the lower boundary of the monoliths. Bacteria-dependent filtration coefficients along pathways of increasing water flux were independent of flow volume, suggesting: (1) tracer or colloid dependent retention; and (2) transport depended on the total volume of contiguous pores accessible for bacteria transport. Management decisions, in this case resulting from the form of organic waste, induced changes in tortuosity and continuity of pores and modified the effective capacity of soil to retain bacteria. Surface application of
Effect of soil depth and texture on fecal bacteria removal from septic effluents
Journal of Water and Health, 2006
This study evaluated the effectiveness of soils with different texture and depth to treat fecal bacteria eluted from a house-hold septic effluent. The assessments were accomplished by leaching undisturbed soil monoliths of 30, 45, and 60 cm thickness and 25 cm in diameter, representing the four different textural groups and hydraulic loadings recommended by the Kentucky Health Department, with domestic wastewater effluent collected regularly from a house-hold septic system. Eluent concentrations were monitored daily over a 15 day period for fecal coliform and fecal streptococci concentrations. The results of the study indicate an alarming frequency of failure to comply with United States Environmental Protection Agency (USEPA) criteria for depth to groundwater, when using a 30 cm vertical separation distance between the bottom of the drain-field and a limiting soil interface. The treatment performance was especially poor in coarse-textured soils. Although biomat development over tim...
Journal of environmental quality
Bacteria transport in soils primarily occurs through soil mesopores and macropores (e.g., biopores and cracks). Field research has demonstrated that biopores and subsurface drains can be hydraulically connected. This research was conducted to investigate the importance of surface connected and disconnected (buried) biopores on Escherichia coli (E. coli) transport when biopores are located near subsurface drains. A soil column (28 by 50 by 95 cm) was packed with loamy sand and sandy loam soils to bulk densities of 1.6 and 1.4 Mg m(-3), respectively, and containing an artificial biopore located directly above a subsurface drain. The sandy loam soil was packed using two different methods: moist soil sieved to 4.0 mm and air-dried soil manually crushed and then sieved to 2.8 mm. A 1-cm constant head was induced on the soil surface in three flushes: (i) water, (ii) diluted liquid swine (Sus scrofa) manure 48 h later, and (iii) water 48 h after the manure. Escherichia coli transport to th...
Influence of soil structure on contaminant leaching from injected slurry
Journal of Environmental Management, 2016
Animal manure application to agricultural land provides beneficial organic matter and 21 nutrients but can spread harmful contaminants to the environment. Contamination of fresh 22 produce, surface water and shallow groundwater with the manure-borne pollutants can be a 23 critical concern. Leaching and persistence of nitrogen, microorganisms (bacteriophage, E. 24 coli, and Enterococcus) and a group of steroid hormone (estrogens) were investigated after 25 © 2016. This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/ disturbed soil. Total recovery of E. coli was significantly higher from the disturbed soil and 41 total leaching of mineral nitrogen was significantly lower from the disturbed soil. Results 42 demonstrate how manure-borne constituents injected into undisturbed soil columns respond 43 more as expected in the field, in terms of leaching and persistence, than do the same 44 constituents injected into typically constructed columns of disturbed soil. 45 46
Transport and Retention of Manure-Borne Coliforms in Soil
Vadose Zone Journal, 2005
Manure is a source of several bacterial pathogens that can potenof dilution, sedimentation, and bacteria die-off. tially contribute to surface and groundwater contamination. Results from most bacterial transport studies in soils are only partially applica-Although soil can mitigate bacterial movement or ble to manure-borne bacteria because microorganisms are released leaching, some bacteria applied onto soil or released along with manure particulates as manure dissolves. The objective of within soil may still be transported through and travel this study was to compare transport of chloride ion, Escherichia coli in the vadose zone to groundwater. Much literature (E. coli) and manure colloids in undisturbed soil columns with a documents bacterial transport from a few meters to well-developed structure. Breakthrough column experiments were 830 m depending on soil or sediment texture and permeconducted with undisturbed, 20-cm long Tyler soil columns from the ability, water saturation degree, and length of time. A horizon. A pulse of 4% filtered bovine manure solution with E. Stoddard et al. (1998) showed that fecal bacteria were coli and KCl was passed through the columns. Escherichia coli contransported to a depth of 90 cm in silt loam soil by the centrations, chloride content, and turbidity were measured in influent first rain after application of dairy manure, when Ͻ2 and in effluent. Columns were cut into 2-cm layers after the experiment to measure: (i) viable bacterial concentrations in pore solution and cm of rain had fallen during a single event. Rainfall or attached to soil; (ii) bulk density; (iii) water content. Companion batch irrigation at intensity of 1 cm h Ϫ1 appeared to be suffiexperiments were performed to measure attachment of E. coli to cient to transport bacteria in poultry manure on the soil in the presence of various amounts of manure. Escherichia coli surface of soil block to a depth of at least 32.5 cm in attachment to soil decreased with increased manure content due to the silt loam soil as result of preferential flow in wellincreased competition for attachment sites. Flow velocity affected structured soil (McMurry et al., 1998). In tilled blocks, E. coli transport and attachment to soil; there was relatively more the fecal coliform concentrations took longer to elute attachment at slower flow velocity than at higher flow velocity. Eschebecause preferential flow paths were disrupted in the richia coli attachment to soil was 18, 5, and 9% at flow velocities of upper 12.5 cm of the soil. Rainfall on well-structured 2.3, 8.4, and 9.3 cm d Ϫ1 , respectively. Spatial variability in soil structure soil caused the preferential movement of fecal bacteria may result in large variations of pore water velocity and consequent differences in transport of manure particulates and bacteria under even in unsaturated flow conditions (McMurry et al., ponded infiltration.
Transport of bacteria from manure and protection of water resources
Applied Soil Ecology, 2004
Survival and transport of pathogens from manure in the environment depend on a number of complex phenomena. An important question is how the properties of such a complex environment as the soil-manure medium impact the persistence of bacteria within the vadose zone. First, manure can change the partitioning of precipitation water between infiltration (enhanced by solid manure) and surface runoff (stimulated by liquid manure). Components of manure, such as straw and coarse organic matter, can strain and filter microorganisms from the transporting water. After infiltrating the soil, the retention of bacteria depends on the physical configuration of soil, the soil chemistry, and the properties of the microbial cells. Transport of bacteria in soils obeys the general laws pertinent to macropore flow and the interaction between particles and surfaces of variable charge. Detailed characterisation of the variable properties within the structured soil profile is a difficult task. Application of manure can result in significant changes in the physical and electrochemical properties of the soils and microbial cells. Such changes can affect the interaction between bacterial cells and soils in several ways: increase filtration, modify the kinetics of the physico-chemical interactions between charged surfaces, and alter the competition for retention sites between suspended soluble and particulate compounds. Survival of faecal bacteria is affected by the physical and chemical conditions existing prior to manure application as well as by conditions imposed by mixing soil and manure. Competitive interaction with native soil bacteria, in the soil-manure mixtures, is an important aspect governing survival of introduced organisms.