A trade-off in activated biochar capping of complex sediment contamination: reduced PAH transport at the cost of potential As mobilisation

publishedVersio

Optimizing Microalgae Biomass Production; Using Nanomaterials for Enhanced Light Transport

Den lave utnyttelsen av lys i nåværende fotobioreaktorer er en stor utfordring når det kommer til å gjøre industriell produksjon av mikroalger økonomisk lønnsomt. En lovende strategi for å forbedre den volumetriske effektiviteten, og dermed lønnsomheten, til biomasseproduksjon fra mikroalger, kan være å bruke nanomaterialer for å forbedre lystransporten i slike systemer. I denne master-oppgaven har effekten av å bruke løsninger med silica- eller sølv-nanopartikler for å fremme god algevekst blitt undersøkt. Sfæriske silica nanopartikler med en gjennomsnittlig diameter på 95 ± 11 nm, 192 ± 24 nm og 256 ± 40 nm har blitt fremstilt ved Stöber-metoden. Absorbansmålinger viste sterkere lysspredning ved kortere bølgelengder og økt spredning for større partikler og høyere konsentrasjoner. Kolloidalt sølv fremstilt ved Lee-Meisel metoden ga sterk spredning av blått lys. Etter å ha studert synteseprosedyren, ble kvasi-sfæriske sølvpartikler oppnådd med en gjennom-snittlig størrelse på 57 ± 14 nm og lokalisert overflate-plasmonresonans ved 431 nm. Vekstforsøk ble utført i en fotobioreaktor bestående av en Multi-Cultivator fra PSI, tilpasset for å muliggjøre implementering av nanopartikler. Dyrkningskar ble laget slik at nanopartiklene ble tilsatt i et eget, lukket rom som omringet algene. Den marine mikroalgen, Rhodomonas baltica, ble brukt som modellorganisme. Følgende kombinasjoner av silica nanopartikkelstørrelser og -konsentrasjoner ble testet; 7217 mg/L med 95 nm, 40 mg/L og 160 mg/L med 192 nm og 40 mg/L med 256 nm. Løsninger med 4 mg/L og 20 mg/L av sølvpartikler på 57 nm ble også undersøkt. Ingen positiv effekt på biomasseproduksjon ble observert i noen av vekstforsøkene

Microplastic in sediments and fauna. Offshore and inshore

Samples of sediment and sediment-dwelling organisms were obtained from the Norwegian Continental Shelf and fjords in Southern Norway. These are referred to as offshore areas and inshore areas, respectively. The sediments samples in inshore areas had significantly higher concentrations of microplastics/kg dw. (mean ± SD: 6 132 ± 5 537) than the offshore sediments (mean ± SD: 1 298 ± 788). This is most likely due to closer proximity to anthropogenic influences and sources of plastic emissions, as well as the presence of accumulation areas of marine debris closer to the coastline. The inshore polychaeta samples trended towards higher concentrations of microplastic items/g w.w. (mean ± SD: 1 773 ± 2 598), than the offshore polychaeta (mean ± SD: 485 ± 607), though due to the large statistical variations in individual biota samples, this cannot be considered statistically significant The most frequently detected plastic polymers were polyolefins (PE, PP), chlorinated-polyethers (PVC, chlorinated PE), PS and rubber in both sediments and polychaeta samples, however there was also large variation in polymer composition between corresponding sediment and polychaeta samples. The environmental impact of microplastics on benthic ecosystems are unknown and in need pf further investigation. The anticipated concentrations of microplastics are expected to increase in the foreseeable future, potentially leading to threshold concentrations, so it is of relevance to repeat this monitoring exercise to account for this. In general the study in this survey were comparable with that of a previous survey also looking at microplastic and sediment concentrations in this region, though some of the polychaete concentrations were higher in this study, but nevertheless the biota-to-sediment enrichment factors (11 to 4 864 gd.w/ gw.w.) were on the low range of the previous study (100 to 11 000 11 to 4 864 gd.w/ gw.w.)

Microplastic in sediments and fauna. Offshore and inshore

Samples of sediment and sediment-dwelling organisms were obtained from the Norwegian Continental Shelf and fjords in Southern Norway. These are referred to as offshore areas and inshore areas, respectively. The sediments samples in inshore areas had significantly higher concentrations of microplastics/kg dw. (mean ± SD: 6 132 ± 5 537) than the offshore sediments (mean ± SD: 1 298 ± 788). This is most likely due to closer proximity to anthropogenic influences and sources of plastic emissions, as well as the presence of accumulation areas of marine debris closer to the coastline. The inshore polychaeta samples trended towards higher concentrations of microplastic items/g w.w. (mean ± SD: 1 773 ± 2 598), than the offshore polychaeta (mean ± SD: 485 ± 607), though due to the large statistical variations in individual biota samples, this cannot be considered statistically significant The most frequently detected plastic polymers were polyolefins (PE, PP), chlorinated-polyethers (PVC, chlorinated PE), PS and rubber in both sediments and polychaeta samples, however there was also large variation in polymer composition between corresponding sediment and polychaeta samples. The environmental impact of microplastics on benthic ecosystems are unknown and in need pf further investigation. The anticipated concentrations of microplastics are expected to increase in the foreseeable future, potentially leading to threshold concentrations, so it is of relevance to repeat this monitoring exercise to account for this. In general the study in this survey were comparable with that of a previous survey also looking at microplastic and sediment concentrations in this region, though some of the polychaete concentrations were higher in this study, but nevertheless the biota-to-sediment enrichment factors (11 to 4 864 gd.w/ gw.w.) were on the low range of the previous study (100 to 11 000 11 to 4 864 gd.w/ gw.w.)