Uporaba metode sledenja delcev za modeliranje transporta in odmiranja Escherichie coli v morju : magistrsko delo

Lešek, Anja (author), Žagar, Dušan (mentor)

Obravnavamo modeliranje transporta in odmiranja bakterije Escherichia coli v morju. Iz merjenih ekstrapoliranih podatkov o slanosti in temperaturi vode, skupaj s podatkom o povprečnem dnevnem sončnem sevanju in motnosti vode, smo po Mancinijevi enačbi izračunali koeficient umrljivosti bakterije E. coli za vsako celico računskega območja, ki zavzema del Koprskega zaliva. S podatki o hidrodinamiki zaliva in z različnimi lastnostmi delcev (bakterij) smo z modificiranim modelom Nafta3D opravili oseminštirideseturno simulacijo hipnega in kontinuirnega izpusta delcev iz enega izvora in analizirali lokacije dveh vrst delcev – prostih bakterij (ECF) in bakterij, pričvrščenih na suspendirane delce (ECA). Nato smo z novim modelom odmiranja bakterije E. coli pri obeh tipih izpusta z razpadno enačbo prvega reda analizirali aktivnost delcev ECA in ECF, ki se je postopoma zmanjševala zaradi dejavnikov okolja, ki smo jih s koeficientom umrljivosti pripisali vsaki celici računskega območja. Ugotovili smo, da ECA v oseminštiridesetih urah potone skoraj na dno in večinoma ne zapusti drugega bazena Luke Koper. Čas, ko odmre 90% bakterij (T90) je pri kontinuirnem izpustu večji od 48 h, pri hipnem pa znaša približno 48 ur. ECF se v višjih slojih hitreje premikajo proti izhodu drugega bazena Luke Koper, kjer bazen zapustijo. Lebdijo višje v vodnem stolpcu, zato je zaradi dejavnikov okolja T90 pri hipnem izpustu enak 6 ur, pri kontinuirnem pa 10 ur.

• Language: Slovenian
• Keywords: modeliranje, E. coli, Mancinijeva enačba, razpadna enačba prvega reda, transport, starost, aktivnost, odmiranje, okoljski dejavniki, Koprski zaliv
• Work type: Master's thesis/paper
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Year: 2018
• PID: 20.500.12556/RUL-101131
• COBISS.SI-ID: 8417889
• Publication date in RUL: 27.04.2018

Secondary language

• Language: English
• Title: Use of the Particle Tracking Method for modeling the transport and deceasing of Escherichia coli in the sea : master thesis

Abstract

We discuss modeling of the transport and deceasing of Escherichia coli in the sea. From the measured and extrapolated data on salinity and water temperature, and the data on average daily solar radiation and water turbidity, the coefficient of E. coli deceasing rate was calculated according to Mancini's equation for each cell of the domain in the part of the Koper Bay. With the modified Nafta3D model, using the precomputed hydrodynamics and different particle (bacteria) properties we performed a forty-eight hour simulation of an instantaneous and a continuous release of particles from a single source, and analyzed locations of two particle types: free E. coli (ECF) and E. coli bound to suspended solids (ECA). Then we analyzed the ECA and ECF activity with the newly developed E. coli decease model at both discharge types using a first order kinetics equation (Chick's law). Bacteriae activity gradually decreased due to environmental factors attributed to each cell of the computational domain by the decease coefficient rate. Within forty-eight hours the ECA sank close to the bottom and mostly stayed within the second basin of the Port of Koper. The decease-time of 90% of the ECA(T90) for continuous discharge was found to be over 48 hours, and about 48 hours for the instantaneous release. The ECF were moving farther from the source and partly left the second basin. ECF hover higher in the water column; therefore, due to the environmental factors, we found the T90 to be 6 and 10 hours at at an instantaneous and a continuous discharge, respectively.

• Keywords: modeling, E. coli, Mancini equation, first order kinetics, transport, age, activity, deceasing, environmental factors, Koper bay