Marine Sewage Outfalls - Environmental Impact Evaluation

Tørken i Western Cape, Sør-Afrika, i 2018-2019 førte til forslaget om å produsere drikkevann for byen Cape Town ved å avsalte sjøvann. Byen slipper ut et stort volum ubehandlet kloakk rett i havet via de marine utløpene rundt Kapphalvøya. Hvis det ikke behandles riktig, kan gjenvunnet vann fra avsaltingsanleggene fungere som en mulig eksponeringsvei for et stort antall nye forurensninger som legemidler og deres metabolitter for befolkningen i Cape Town. I prosjektet er vannprøver og marine organismer samlet inn og analysert for vanlige forurensninger funnet i kloakk (kjemisk overvåking) både i Cape Town og Stavanger. Det er utført caging studier med blåskjell i nærheten av avløpsrør i begge byene for å se på de biologiske effekter (biologisk overvåking). I tillegg ble det utført en laboratorieeksponeringsstudie med makk (Nereis virens) eksponert for et enkelt legemiddel, nemlig amitriptylin. Kombinasjonen av kjemiske og biologiske analyser har gitt en god evaluering av helsen til havet rundt Cape Town og rundt kloakkutløpet for Stavanger-regionen. Funnene fra studiene viser at en rekke legemidler finnes i konsentrasjoner som kan detekteres i havet rundt Cape Town og at kjemikaliene bioakkumuleres i biota. Tilsvarende studier fra Stavanger viser færre legemidler i konsentrasjoner som kan detekteres i avløpet fra renseanlegget. Generelt er det for begge lokalitetene at sedimenter har en mye høyere konsentrasjon av miljøgifter enn konsentrasjoner funnet i vannprøver, noe som betyr at biota som lever på og i sedimentene i større grad er utsatt for miljøgifter. Bioakkumulering er bekreftet både i prøver samlet på steder rundt kloakkutløpene i Cape Town og i laboratorieeksponeringsstudier utført i Stavanger. Caging studier vil mest sannsynlig også bekrefte dette når det arbeidet er avsluttet. Disse funnene fremhever behovet for bedre renseanlegg for kloakk som kan fjerne legemidler. Dette bør også fasiliteres ved å utvikle legemidler som har kortere levetid i miljøet etter bruk.

The results obtained in the project have been disseminated in peer review journals, at scientific conferences and to the public through chronicles (kronikker) in newspapers and forskning.no. Our first report from the project (Ojemaye et al. Sci. Total Environ. 2020, 738, 140346) got the attention of the city council of Cape Town who attacked the study due to the results showed that the water and sand in and around one of their more popular beaches do not have the quality one would like, and we do find bioaccumulation of contaminants in biota from that ocean side. This resulted in a rather unusual publication in a scientific journal by Colenbrander et al. (Sci. Total Environ. 2021, 755, 142576) where they challenged our findings. The points they were challenging was related to the source of the pollutants and the challenges were answered by us in a second paper in the same journal (Sci. Total Environ. 2921, 778, 146057). This extra attention brought by the challenge from Colenbrander et al. helped spread the results of our research even further. The panel debate in December 2021 entitled From Toilet to Sea: Research collaboration to ensure safe water organized by Science Forum South Africa was an excellent opportunity to disseminate results and inform policy makers from around the world (predominantly African policy makers). We also followed that session up with a chronical in forskning.no. so that Norwegian public also could get an update on the situation related to pharmaceuticals in the marine environment. Due to delays in sample analysis (analytical chemistry) we do have results that have not been disseminated to date. This will be done during 2023 and will both be in the form of scientific articles in peer review journals and as talks. Worth mentioning is that the results from the project will be presented at SETAC Europe in Dublin this May as a platform lecture. The SANOCEAN project will be followed up in the INTPART project that is based on this project. The INTPART project will run through 2023 and results from the SANOCEAN project will be discussed and shared at our workshop in Cape Town in March and at other events organized by INTPART.

The ongoing drought in the Western Cape has led to the proposal to produce drinking water for the City of Cape Town by seawater desalination plants. The City discharges a high volume of untreated sewage effluent into the ocean via the marine outfalls located around the Cape Peninsula. If not treated properly, reclaimed water from the desalination plants can act as a possible exposure pathway to a high number of emerging contaminants and their metabolites. In this project, water samples and aquatic organisms will be collected and analysed for common contaminants found in sewage (chemical monitoring). Also a caging study with mussels will be conducted in order to look at biological effects (biological monitoring). The combination of these analyses will provide a good evaluation of the health of the ocean around Cape Town. The findings from the project will be of good use when the city is planning new desalination plants and sewage treatment plants. A sewage plume model will be made, making it possible to predict where the plume will go under different weather conditions. Communication both with the lay public, politicians and scientists will be an important part of the project. Dissemination of results will take place by means of YouTube movies, articles online, newspaper articles, public speaking, and scientific articles. An app will also be developed in the project that will give a real time update on the pollution situation at the city beaches at any given time.