Microplastics Accumulation in Recirculating Aquaculture Systems (RAS)

It has in recent years been a shift in the land-based aquaculture production from flow through systems (FTS) to recirculating aquaculture systems (RAS). With emerging use of RAS, it is necessary with knowledge regarding potential issues, whereas one potentially increasing problem is accumulation of microplastics (MP) in the RAS water. The objects of this study were to determine MPs concentration in RAS water, if the MPs originated from within the RAS, and provide a size distribution of the particles. RAS water were sampled in triplicates from three different RAS at three different locations in Norway. The water for each RAS were sampled effluent of the fish tank, effluent of the drum filter, and effluent of the biofilter as well as make-up water and sludge. Bio-media from the corresponding RAS were also sampled. Organic material in the water samples were digested prior to filtration, and filters were stained with Nile Red for quantification. There were found MPs in all the RAS water samples with mean concentration of 61 MP/L at Sunndalsøra RAS, 371 MP/L at the commercial site RAS and 41 MP/L at Kårvika RAS. There were higher concentrations in the RAS water than in the make-up water for all locations, indicating that the MPs originated from within the systems. Sludge samples were only possible to quantify from Kårvika RAS, while sampling were not performed at the commercials site and MPs concentration were too high to perform a count in Sunndalsøra RAS. The sludge samples support that the origin of MPs are within the system, as more MPs leave then enters the RAS. Nuclear magnetic resonance (NMR) spectroscopy analyses gave almost identical signals as their reference, which were the corresponding bio-media. The MPs also showed indistinguishable similarities with polyethylene (PE), which the bio-media were made off. There were found no significant trends regarding concentration at the different sampling sites. All RAS had similar size distribution of the MPs with approximately 75% of the particles being less than 100 μm. In conclusion, there were high concentrations of MPs in RAS which likely were due to shattering of the bio-media. Future research is necessary to determine an accumulation rate, but the high abundance of MPs proves the emerging issue regarding MPs. And although RAS has the potential to be the environmental winner within aquaculture, there still are opportunities for improvement

VNIbCReg: VICReg with Neighboring-Invariance and better-Covariance Evaluated on Non-stationary Seismic Signal Time Series

One of the latest self-supervised learning (SSL) methods, VICReg, showed a great performance both in the linear evaluation and the fine-tuning evaluation. However, VICReg is proposed in computer vision and it learns by pulling representations of random crops of an image while maintaining the representation space by the variance and covariance loss. However, VICReg would be ineffective on non-stationary time series where different parts/crops of input should be differently encoded to consider the non-stationarity. Another recent SSL proposal, Temporal Neighborhood Coding (TNC) is effective for encoding non-stationary time series. This study shows that a combination of a VICReg-style method and TNC is very effective for SSL on non-stationary time series, where a non-stationary seismic signal time series is used as an evaluation dataset

Dimensjonar ved ei elv: Bagmati River, Kathmandu, Nepal

Objectives: Problemstillinga kjem til uttrykk gjennom tre spørsmål med underspørsmål: 1. Har elvas fysiske degradering ført til endringar i korleis folk oppfattar og konseptualiserer elva? - Kan det observerast endringar i korleis folk tilskriv elva meining? 2. Kan ein sjå ulikskap i tilskriven meining til Bagmati etter alder? Har yngre menneske ei anna oppfatning av elva enn eldre menneske? 3. Om persepsjonen har blitt endra, har fysiske endringar i Bagmati endra folks ritualer og praksis til elva? - På kva måte har rituala endra seg, kva ligg i endring av praksisen? Ved å setje opp dette i stikkordsform, vil eg altså konsentrere meg om: 1. Persepsjon, endring i oppfatning av elva. 2. Konsekvensen av endra oppfatning, endring av praksis og ritualer

Discourses of climate change education: The case of geography textbooks for secondary and higher secondary education in South Africa and Norway

The purpose of the article, which is a comparative study, is to explore climate change discourses in South African and Norwegian geography textbooks by addressing the following questions: What policy discourses of climate change can be identified in the textbooks? How is the climate change content of geography textbooks influenced by predominant discourses in society? The authors assert that problems and solutions to climate change in textbooks are influenced by dominant discourses of climate change in society. Despite expecting to find a strong emphasis on ecological modernization and a win-win discourse in the Norwegian context, and perhaps a stronger focus on civic environmentalism and global injustice in the South African context, their findings reflected that for both countries, textbooks predominantly leaned towards belief in international agreements and green governmentality. Some emphasis was placed on ecological modernization, particularly in South Africa, while civic environmentalism and global injustice perspectives were marginal and lacked context. The overlapping nature of perspectives identified in the textbooks also demonstrated the complexity of identifying problems and solutions connected to climate change. The authors conclude that political ecology can offer a consistent didactical framework to examine the diversity of interests, perspectives and ‘stories’ about climate change at different scales