RESUMEN
The time and location of sampling as well as the number of samples per season can influence a reliable assessment of bathing water quality. In this study, we investigated the spatio-temporal variation of fecal indicator bacteria (FIB) density and the effects of FIB variability and sampling frequency on the assessment of a single sample and the annual and final assessment of coastal bathing water quality. Increasing the number of samples from 10 to 20 per bathing season had a significant impact on bathing water quality assessment at sites where water quality fluctuations had previously been observed, resulting in a change in water quality to a lower category in 36 % of annual and 54 % of final assessments, suggesting that the minimum number of samples per season should be increased at such sites. Increasing the number of samples at sites assessed as excellent over a longer period had no impact on water quality assessment. Spatial and temporal variations in FIB density were significant at a considerable number of sites both in the single sample assessment and in the annual and final assessment. Bathing water quality was spatially unrepresentative at a quarter of the sites analyzed and temporally unrepresentative at a fifth, as there was at least one additional point with a lower bathing water quality than the official sampling point or the bathing water quality was lower in the afternoon than in the morning. When revising the current recreational water quality regulations, the impact of sampling frequency of and of spatio-temporal variation of FIB density on the relevance of bathing water quality assessment at sites subjected to pollution needs to be seriously considered.
Asunto(s)
Playas , Monitoreo del Ambiente , Heces , Microbiología del Agua , Calidad del Agua , Heces/microbiología , Monitoreo del Ambiente/métodos , Agua de Mar/microbiología , Bacterias/aislamiento & purificación , Estaciones del Año , Análisis Espacio-TemporalRESUMEN
Ports are subject to a variety of anthropogenic impacts, and there is mounting evidence of faecal contamination through several routes. Yet, little is known about pollution in ports by faecal indicator bacteria (FIB). FIB spatio-temporal dynamics were assessed in 12 ports of the Adriatic Sea, a semi-enclosed basin under strong anthropogenic pressure, and their relationships with environmental variables were explored to gain insight into pollution sources. FIB were abundant in ports, often more so than in adjacent areas; their abundance patterns were related to salinity, oxygen, and nutrient levels. In addition, a molecular method, quantitative (q)PCR, was used to quantify FIB. qPCR enabled faster FIB determination and water quality monitoring that culture-based methods. These data provide robust baseline evidence of faecal contamination in ports and can be used to improve the management of routine port activities (dredging and ballast water exchange), having potential to spread pathogens in the sea.
Asunto(s)
Heces/microbiología , Microbiología del Agua , Bacterias/genética , Bacterias/aislamiento & purificación , Monitoreo del Ambiente/métodos , Mar Mediterráneo , Reacción en Cadena en Tiempo Real de la Polimerasa , Salinidad , Estaciones del Año , Navíos , Análisis Espacio-Temporal , Encuestas y Cuestionarios , Calidad del AguaRESUMEN
This study defines performance characteristics of the temperature-modified ISO 9308-1 method for E. coli enumeration in bathing water. After a 4-hour resuscitation period at 36⯱â¯2⯰C, the incubation temperature was changed to 44⯱â¯0.5⯰C. Elevated incubation temperature significantly suppressed the growth of thermo-intolerant bacteria, and enhanced the selectivity of Chromogenic Coliform Agar (CCA) up to 49.5% for inland and up to 66.0% for coastal water. Consequently, most of the selectivity-related performance characteristics are improved. Relative recovery was determined by comparing an alternative method against the reference, ISO 9308-1:2014 method, following the criteria set out in ISO 17994:2014. Temperature modification did not significantly alter the results and the methods were evaluated as "not different" for both, coastal and inland waters. Chromogenic Coliform Agar was assessed as a suitable medium for reliable E. coli enumeration in bathing water when incubated for 17-19â¯h at 44⯱â¯0.5⯰C after the 4-5â¯h resuscitation period at 36⯱â¯2⯰C.