Microbial Source Tracking as a Method of Determination of Beach Sand Contamination

Abstract

Beach sand may act as a reservoir for numerous microorganisms, including enteric pathogens. Several of these pathogens originate in human or animal feces, which may pose a public health risk. In August 2019, high levels of fecal indicator bacteria (FIB) were detected in the sand of the Azorean beach Prainha, Terceira Island, Portugal. Remediation measures were promptly implemented, including sand removal and the spraying of chlorine to restore the sand quality. To determine the source of the fecal contamination, during the first campaign, supratidal sand samples were collected from several sites along the beach, followed by microbial source tracking (MST) analyses of Bacteroides marker genes for five animal species, including humans. Some of the sampling sites revealed the presence of marker genes from dogs, seagulls, and ruminants. Making use of the information on biological sources originating partially from dogs, the municipality enforced restrictive measures for dog-walking at the beach. Subsequent sampling campaigns detected low FIB contamination due to the mitigation and remediation measures that were undertaken. This is the first case study where the MST approach was used to determine the contamination sources in the supratidal sand of a coastal beach. Our results show that MST can be an essential tool to determine sources of fecal contamination in the sand. This study shows the importance of holistic management of beaches that should go beyond water quality monitoring for FIB, putting forth evidence for beach sand monitoring.

Level of Heavy Metals and Pathogenic Bacteria in Tap Water of Rusafa side Hospitals in Baghdad

“…One of the most important reasons that reduced the presence of indicators of contamination of drinking water supplied to hospitals by fecal enteric bacteria is the high level of chlorine that was estimated in water supplied to hospitals [14,15]. The high levels of chlorine play a major role in eliminating pathogenic microorganisms, especially fecal bacteria, as fecal bacteria are isolated from humans and animals [16]. Fecal bacteria are characterized by having low resistance to chlorine as compared with environmental bacteria in soil and water, which have adapted to hard environmental conditions [17][18][19].…”

Characterization of the Pathogenic Potential of the Beach Sand Microbiome and Assessment of Quicklime as a Remediation Tool

“…Diseases can be transmitted via the fecal-oral transmission route and associated with gastrointestinal illnesses, but also inhalation, dermal, and ocular contact routes can be responsible for respiratory illnesses, rash, and eye ailments. Among these, gastrointestinal illnesses are often the prevalent occurring pathologies compared to other illnesses, in beach recreational exposure, due to elevated contamination by fecal indicator bacteria (FIB), including fecal coliforms, Escherichia coli , and enterococci of human and animal gut origin, transported to the sand via water or directly spread by animals [ 1 , 2 , 3 ].…”

“…However, while water quality is regulated by FIB enumeration, FIB/microbiological testing is not performed in the sand, thus providing inadequate information about contamination sources and associated health risk in beaches. Some studies regarding the analysis of sand contamination are available in the scientific literature, reporting the application of the MST method as a useful tool to assess beach sand contamination [ 1 ]. Besides, it was observed that high similarity in sand and water from the same site likely reflects anthropogenic contamination [ 9 ].…”

“…Besides, it was observed that high similarity in sand and water from the same site likely reflects anthropogenic contamination [ 9 ]. In addition, high FIB levels were reported in the sand of Azorean beaches, determining the contamination biological source by MST analyses of human and animal markers [ 1 ]; based on this, remediation measures were promptly implemented, including sand removal and spraying it with chlorine, to restore the beach sand quality. Overall, available studies support the need to perform community-based molecular studies to identify sources and potential impact of microbial pollution in the environment.…”

“…Last, based on the existing data, it appears that effective and safe methods for sand decontamination are needed. Reported remediation measures include sand removal and treatment by chlorine, to restore the biosafety sand quality [ 1 ]. Besides, quicklime used at 10–20% concentration ( w / v ) was reported as an effective treatment for highly contaminated sludges from wastewater plants [ 14 ].…”