Control of viral contamination of reclaimed irrigated vegetables by drip irrigation

Persistent Link:
http://hdl.handle.net/10150/280675
Title:
Control of viral contamination of reclaimed irrigated vegetables by drip irrigation
Author:
Alum, Absar
Issue Date:
2001
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
A number of factors have contributed to the interest in reclaimed wastewater irrigation of vegetables. However safety of water as related to fresh cut vegetables has been a paramount concern of responsible agencies, growers and consumers. The objective of this study was to evaluate the risk mitigation potential of subsurface drip irrigation during reclaimed wastewater irrigation. Virus detection methodologies on produce were first optimized. Beef extract (3%) +0.04M sodium pyrophosphate was found to be the most efficient eluent to recover viruses from soil and plant material. The recovery efficiency of poliovirus type l and adenovirus type 40 from Pima clay loam soil ranged from 12--16%, and recoveries from Brazito sandy loam ranged from 58--81%. The recovery efficiencies of poliovirus type 1, adenovirus type 40, MS2 and PRD1 from lettuce ranged from 45 to 70%. The recovery efficiencies of MS2 and PRD1 from tomato fruit were in the range of 90%. Poliovirus type 1, adenovirus type 40, MS2 and PRD1 survived longer in Pima clay loam than in Brazito sandy loam. All enteric viruses remained stable at 4°C suggesting that little virus inactivation occurs during transportation and marketing. Poliovirus type 1 and adenovirus type 40 lost 1 log₁₀ in 11 and 17 days respectively on lettuce at room temperature. Hepatitis A virus lost 2.5 log₁₀ in 50 days on a lettuce head in a greenhouse during the winter season. Tomato, lettuce and cucumber crops were irrigated with virus-seeded water by subsurface and surface drippers. Subsurface drip irrigation resulted in 99% less viral contamination of vegetable leaves as compared to surface drip irrigation. The greatest risk of infection occurs from the outer leaves of lettuce. The risk of infection from consumption of reclaimed wastewater irrigated tomatoes and cucumber was 32% and 72% less than lettuce. The risk of infection from rotavirus by ingestion of vegetables is greater than poliovirus type 1. The risk of infection from subsurface drip irrigated vegetables did not approach the United States Environmental Protection Agency's acceptable annual risk (1:10,000) until the concentration of viruses in the irrigation water reached 100/l. No internal contamination by viruses of the vegetables was observed during their growth. The coliphages PRD1 survived longer than poliovirus type I, adenovirus type 40, and MS2. It would thus appear to be a good model for studying the persistence of those viruses on produce and in irrigated agricultural systems.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Microbiology.; Agriculture, Soil Science.; Environmental Sciences.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Soil, Water and Environmental Science
Degree Grantor:
University of Arizona
Advisor:
Gerba, Charles P.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleControl of viral contamination of reclaimed irrigated vegetables by drip irrigationen_US
dc.creatorAlum, Absaren_US
dc.contributor.authorAlum, Absaren_US
dc.date.issued2001en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractA number of factors have contributed to the interest in reclaimed wastewater irrigation of vegetables. However safety of water as related to fresh cut vegetables has been a paramount concern of responsible agencies, growers and consumers. The objective of this study was to evaluate the risk mitigation potential of subsurface drip irrigation during reclaimed wastewater irrigation. Virus detection methodologies on produce were first optimized. Beef extract (3%) +0.04M sodium pyrophosphate was found to be the most efficient eluent to recover viruses from soil and plant material. The recovery efficiency of poliovirus type l and adenovirus type 40 from Pima clay loam soil ranged from 12--16%, and recoveries from Brazito sandy loam ranged from 58--81%. The recovery efficiencies of poliovirus type 1, adenovirus type 40, MS2 and PRD1 from lettuce ranged from 45 to 70%. The recovery efficiencies of MS2 and PRD1 from tomato fruit were in the range of 90%. Poliovirus type 1, adenovirus type 40, MS2 and PRD1 survived longer in Pima clay loam than in Brazito sandy loam. All enteric viruses remained stable at 4°C suggesting that little virus inactivation occurs during transportation and marketing. Poliovirus type 1 and adenovirus type 40 lost 1 log₁₀ in 11 and 17 days respectively on lettuce at room temperature. Hepatitis A virus lost 2.5 log₁₀ in 50 days on a lettuce head in a greenhouse during the winter season. Tomato, lettuce and cucumber crops were irrigated with virus-seeded water by subsurface and surface drippers. Subsurface drip irrigation resulted in 99% less viral contamination of vegetable leaves as compared to surface drip irrigation. The greatest risk of infection occurs from the outer leaves of lettuce. The risk of infection from consumption of reclaimed wastewater irrigated tomatoes and cucumber was 32% and 72% less than lettuce. The risk of infection from rotavirus by ingestion of vegetables is greater than poliovirus type 1. The risk of infection from subsurface drip irrigated vegetables did not approach the United States Environmental Protection Agency's acceptable annual risk (1:10,000) until the concentration of viruses in the irrigation water reached 100/l. No internal contamination by viruses of the vegetables was observed during their growth. The coliphages PRD1 survived longer than poliovirus type I, adenovirus type 40, and MS2. It would thus appear to be a good model for studying the persistence of those viruses on produce and in irrigated agricultural systems.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Microbiology.en_US
dc.subjectAgriculture, Soil Science.en_US
dc.subjectEnvironmental Sciences.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineSoil, Water and Environmental Scienceen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorGerba, Charles P.en_US
dc.identifier.proquest3016457en_US
dc.identifier.bibrecord.b41885867en_US
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