Influence of sampling frequency on annual assessment of microbiological quality of marine bathing water on beaches of Kaštela

U ovom radu ispitivan je utjecaj učestalosti uzorkovanja mora za kupanje na području grada Kaštela na godišnju ocjenu kakvoće mora za kupanje. Ispitivanja su provedena na 11 plaža u razdoblju od 16. svibnja do 29. rujna 2022. Ukupno je ispitano 240 uzoraka a određivan je broj indikatorskih bakterija, crijevnih enterokoka i Escherichia coli. Rezultati su pokazali da češće uzorkovanje utječe na godišnju ocjenu kakvoće mora za kupanje. U slučaju standardnog dvotjednog uzorkovanja (10 uzoraka u sezoni), kakvoća je uglavnom bolja u usporedbi s kakvoćom temeljenom na rezultatima tjednog uzorkovanja (20 uzoraka u sezoni). Također, kakvoća mora pri popodnevnom uzorkovanju bila je bolja nego pri jutarnjem uzorkovanju. Kakvoća mora određena prema kriterijima Direktive o upravljanju kvalitetom vode za kupanje bila je bolja od one određene prema hrvatskim kriterijima. Provođenje ispitivanja kakvoće mora za kupanje u vremenskim intervalima češćima od propisanih (20 uzoraka u sezoni u usporedbi s 10 uzoraka u sezoni) dovelo je do snižavanja godišnje ocjene kakvoće mora za kupanje na području Kaštela.The influence of the frequency of marine bathing water sampling in Kaštela town area on the annual assessment of marine bathing water quality was tested. The research was conducted on 11 marine beach sites from 16 May to 29 September 2022. A total of 240 samples were tested as well as a number of indicator bacteria: intestinal enterococci and Escherichia coli. The results show that more frequent sampling has an effect on the annual assessment of marine beach water quality. With standard bi-weekly sampling (10 samples per season), quality was generally better than with weekly sampling (20 samples per season). In addition, marine beach water quality was better when sampled in the afternoon than when sampled in the morning. The quality of marine beach water assessed according to the Bathing Water Directive criteria was better than that graded according to the Croatian criteria. Testing marine bathing water more frequently than it is currently assigned by the law (20 samples per season compared to 10 samples per season) resulted in lower grade for annual marine bathing water quality in Kaštela town area