Ultraviolet germicidal irradiation of melted snow and ice samples: inactivation of microorganisms and effects on insoluble microparticles

Abstract

The long-term refrigerated storage of melted snow and/or ice samples for analyses of insoluble microparticles (hereafter, microparticles) may be limited by increases in the biological particle concentration caused by microbial growth after ~1–2 weeks. In this study, we examined an ultraviolet (UV) disinfection method for the storage of melted snow and/or ice samples and determined the effects of this method on microparticles. Surface snow obtained from Glacier No. 31 in the Suntar-Khayata Range, eastern Siberia, Russia was divided into two portions for UV treatment and untreated controls. Microparticle concentrations and size distributions (in the range of 0.52–12.0 μm) in the samples were measured using a Coulter counter. Whereas the microparticle concentration in untreated samples increased, no obvious increase was observed over 53 d in the samples subjected to UV treatment. Microbial growth was detected in only untreated samples using a viable particle counter. In addition, the original microparticle concentrations and size distributions were unaffected by UV treatment. Our results demonstrated that the microparticle size distribution in untreated melted water samples reflects the growth, decomposition and succession of microorganisms over time and further indicate that UV irradiation is effective for long-term storage for microparticle analysis.

Preliminary Study on Microbial Deterioration Control and Effectiveness Evaluation in the Neolithic Prehistoric Archaeological Site of Dadiwan, Northwest China

“…Ultraviolet sterilization as one of the physical sterilization methods is characterized by its simplicity of operation, high spectral efficiency, and low secondary pollution and has been commonly used to eliminate microorganisms in the food and medical industry but is rarely used in the conservation of cultural relics [73][74][75]. With the rolling out of novel ultraviolet light sources, it is gradually gaining popularity as one of the methods for eliminating harmful microorganisms on the surfaces of cultural sites [76,77]. The principle of ultraviolet sterilization involves the destruction and alteration of the molecular structure of DNA in microbial cells by UV irradiation so that the microbial cells die or cannot reproduce to achieve the effect of sterilization [78].…”