Leaching of Cryptosporidium parvum Oocysts, Escherichia coli, and a Salmonella enterica Serovar Typhimurium Bacteriophage through Intact Soil Cores following Surface Application and Injection of Slurry

Abstract

Increasing amounts of livestock manure are being applied to agricultural soil, but it is unknown to what extent this may be associated with contamination of aquatic recipients and groundwater if microorganisms are transported through the soil under natural weather conditions. The objective of this study was therefore to evaluate how injection and surface application of pig slurry on intact sandy clay loam soil cores influenced the leaching of Salmonella enterica serovar Typhimurium bacteriophage 28B, Escherichia coli, and Cryptosporidium parvum oocysts. All three microbial tracers were detected in the leachate on day 1, and the highest relative concentration was detected on the fourth day (0.1 pore volume). Although the concentration of the phage 28B declined over time, the phage was still found in leachate at day 148. C. parvum oocysts and chloride had an additional rise in the relative concentration at a 0.5 pore volume, corresponding to the exchange of the total pore volume. The leaching of E. coli was delayed compared with that of the added microbial tracers, indicating a stronger attachment to slurry particles, but E. coli could be detected up to 3 months. Significantly enhanced leaching of phage 28B and oocysts by the injection method was seen, whereas leaching of the indigenous E. coli was not affected by the application method. Preferential flow was the primary transport vehicle, and the diameter of the fractures in the intact soil cores facilitated transport of all sizes of microbial tracers under natural weather conditions.

Transport of Cryptosporidium parvum Oocysts in Soil Columns following Applications of Raw and Separated Liquid Slurries

“…Retention of Escherichia coli similar to that found for oocysts in our study was seen for E. coli when using the same soil columns (1). Forslund et al (15) found that intact soil cores injected with raw pig slurry spiked with C. parvum leached 10 times more oocysts than did soil cores applied with slurry on the surface after 148 days of study under natural climate conditions. However, the amount of oocysts retained in the soil was not determined (15).…”

“…Other studies have investigated the transport of Cryptosporidium oocysts through soil (4,8,9,15,25,32), but none of these studies evaluated the leaching of oocysts following application of separated liquid slurry containing oocysts. In our study, soil columns with injected liquid slurry released more oocysts over the 4-week study period than did soil columns with added raw slurry regardless of the application method, although the difference was not statistically significant.…”

“…Several studies have looked at the transport of oocysts through soil, but only a few studies have determined the viability and/or infectivity of oocysts in leachate and soil (4,15,22 a That is, the sum of total oocysts recovered from the0.01% dry matter content from the three soil sections. b LS-ME (95% CI), back-transformed least-significant mean estimate (95% confidence interval).…”

Interaction Forces Drive the Environmental Transmission of Pathogenic Protozoa

“…Soil physicochemical properties, e.g., mineralogy, natural organic matter content, and pH, critically affect the parasite-particle interactions and the mobilization behavior of Cryptosporidium oocysts (43,52,79,81,82). Spatial dissemination of excreted parasites depends also on local hydrodynamic forces and occurs mainly by leaching, typically following heavy rainfalls, leading to the possible entry of the parasites into water (39,84). It has been shown that wetlands with established vegetation may efficiently retain parasites, while degraded habitats promote pathogen pollution of waters, with great impact on humans and animals (100,106).…”

<b>Enteropathogenic bacterial contamination of a latosol following application of organic fertilizer

“…Although contamination by these organisms is of concern given the risk associated with the transmission of infectious and parasitic diseases through the food chain (MACIOROWSKIA et al, 2007;SILVA et al, 2005), other studies show that enteric organisms either do not survive or have a high rate of decline in fertilized soil (GAGLIARDI; KARNS, 2002;GARCÍA-ORENES et al, 2007;TALLON et al, 2007;ZIEMER et al, 2010). The discrepancies in the literature about enteropathogenic bacterial contamination of soil are related to the many different factors that affect the survivability of enteric organisms in the soil, including the type of organic fertilizer; fertilized crop, management and dosage; the use of mitigation practices; and environmental factors such as soil type, pH, humidity and temperature (MACIOROWSKIA et al, 2004;FORSLUND et al, 2011). However, the survival of pathogenic organisms in latosols fertilized with poultry manure has not been studied in Brazilian soils and climate conditions, and there are only a few reports from other countries (McMURRY et al, 1998).…”