Student Research Reports
IMPACT OF RAINWATER ON SEA QUALITY IN LAPAD BAY OUTSIDE THE 2021 TOURIST SEASON
Organization(s):Ekonomska i trgovačka škola Dubrovnik
Country:Croatia
Student(s):Matea Maslać
Matej Ban
Petra Lalić
Grade Level:Secondary School (grades 9-12, ages 14-18)
GLOBE Teacher:Sanja Culic
Contributors:prof.dr.sc. Renata Matoničkin Kepčija
Ines Srzić
Report Type(s):Standard Research Report
Protocols:Clouds, Precipitation, Alkalinity, Conductivity, Dissolved Oxygen, Nitrates, pH, Salinity, Water Temperature, Water Transparency
Language(s):Other (Croatia)
Date Submitted:01/06/2023
The aim of the research was to assess whether the rainwater affects the reduction of seawater quality in Lapad Bay. In the Bay of Lapad there is the beach of the same name, one of the most beautiful in Dubrovnik. Next to the beach there is a rainwater outlet channel where untreated rainwater enters the sea during the rain. To assess the quality of the sea water, we have selected three locations within the bay itself. For the research, we have used GLOBE protocols for hydrology: determination of sea pH, amount of dissolved oxygen, salinity and sea temperature. Using the GLOBE Atmospheric Protocol, we measured air temperature, determined cloud cover and cloud types, the amount and pH of rain. In order to prove the presence of faecal contamination bacteria, we performed microbiological analysis at the Institute of Public Health. Measurements were performed eight times, after a long dry period and immediately after a small amount of precipitation (less than 8 mm / 24 h) and after a larger amount of precipitation (more than 8 mm / 24 h) in the period from October 2021 to February 2022. The results of the research indicate the presence of faecal pollution bacteria in the sea at the first location where the stormwater drainage outlet is, both during rain and during the dry season, which indicates a constant inflow of fecal water. By moving away from the source of pollution, the number of bacteria of fecal pollution indicators does not exceed the permitted limits according to the Standard for the assessment of marine quality