| 1. |
- Brandt, Josef, et al.
(författare)
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Assessment of Subsampling Strategies in Microspectroscopy of Environmental Microplastic Samples
- 2021
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Ingår i: Frontiers in Environmental Science. - : Frontiers Media SA. - 2296-665X. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The analysis of environmental occurrence of microplastic (MP) particles has gained notable attention within the past decade. An effective risk assessment of MP litter requires elucidating sources of MP particles, their pathways of distribution and, ultimately, sinks. Therefore, sampling has to be done in high frequency, both spatially and temporally, resulting in a high number of samples to analyze. Microspectroscopy techniques, such as FTIR imaging or Raman particle measurements allow an accurate analysis of MP particles regarding their chemical classification and size. However, these methods are time-consuming, which gives motivation to establish subsampling protocols that require measuring less particles, while still obtaining reliable results. The challenge regarding the subsampling of environmental MP samples lies in the heterogeneity of MP types and the relatively low numbers of target particles. Herein, we present a comprehensive assessment of different proposed subsampling methods on a selection of real-world samples from different environmental compartments. The methods are analyzed and compared with respect to resulting MP count errors, which eventually allows giving recommendations for staying within acceptable error margins. Our results are based on measurements with Raman microspectroscopy, but are applicable to any other analysis technique. We show that the subsampling-errors are mainly due to statistical counting errors (i.e., extrapolation from low numbers) and only in edge cases additionally impacted by inhomogeneous distribution of particles on the filters. Keeping the subsampling-errors low can mainly be realized by increasing the fraction of MP particles in the samples.
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| 2. |
- Brandt, Josef, et al.
(författare)
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Deep Learning for Reconstructing Low-Quality FTIR and Raman Spectra─A Case Study in Microplastic Analyses
- 2021
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 93:49, s. 16360-16368
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Tidskriftsartikel (refereegranskat)abstract
- Herein we report on a deep-learning method for the removal of instrumental noise and unwanted spectral artifacts in Fourier transform infrared (FTIR) or Raman spectra, especially in automated applications in which a large number of spectra have to be acquired within limited time. Automated batch workflows allowing only a few seconds per measurement, without the possibility of manually optimizing measurement parameters, often result in challenging and heterogeneous datasets. A prominent example of this problem is the automated spectroscopic measurement of particles in environmental samples regarding their content of microplastic (MP) particles. Effective spectral identification is hampered by low signal-to-noise ratios and baseline artifacts as, again, spectral post-processing and analysis must be performed in automated measurements, without adjusting specific parameters for each spectrum. We demonstrate the application of a simple autoencoding neural net for reconstruction of complex spectral distortions, such as high levels of noise, baseline bending, interferences, or distorted bands. Once trained on appropriate data, the network is able to remove all unwanted artifacts in a single pass without the need for tuning spectra-specific parameters and with high computational efficiency. Thus, it offers great potential for monitoring applications with a large number of spectra and limited analysis time with availability of representative data from already completed experiments. © 2021 The Authors. Published by American Chemical Society.
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| 3. |
- Brandt, Josef, et al.
(författare)
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High-Throughput Analyses of Microplastic Samples Using Fourier Transform Infrared and Raman Spectrometry
- 2020
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Ingår i: Applied Spectroscopy. - : SAGE Publications. - 0003-7028 .- 1943-3530. ; 74:9, s. 1185-1197
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Tidskriftsartikel (refereegranskat)abstract
- Determining microplastics in environmental samples quickly and reliably is a challenging task. With a largely automated combination of optical particle analysis, Fourier transform infrared (FT-IR), and Raman microscopy along with spectral database search, particle sizes, particle size distributions, and the type of polymer including particle color can be determined. We present a self-developed, open-source software package for realizing a particle analysis approach with both Raman and FT-IR microspectroscopy. Our software GEPARD (Gepard Enabled PARticle Detection) allows for acquiring an optical image, then detects particles and uses this information to steer the spectroscopic measurement. This ultimately results in a multitude of possibilities for efficiently reviewing, correcting, and reporting all obtained results.
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| 4. |
- Hassellöv, Martin, et al.
(författare)
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Utveckling av analysmetoder för mikroplast i miljöprover för forskning och miljöövervakning
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- För att bättre förstå omfattning och miljöpåverkan av mikroplast samt kunna ta beslut om lämpliga åtgärder och uppföljning, är det av yttersta vikt att det finns tillförlitliga mätmetoder. Det har lyfts fram som prioriterade områden för vidare forskning och utveckling under lång tid och även om stora framsteg har gjorts är det fortfarande ett viktigt område i internationella forskningsagendor.För att en mätmetod ska anses tillförlitlig bör syftet ta ett helhetsperspektiv längs hela den analytiska kedjan från provtagning, upparbetning, instrumentell analytisk bestämning, definitioner och rapportering. Jämförbarhet eller harmonisering mellan metoder är viktigt liksom att metoden kan valideras och visa att syftet kan uppfyllas med metoden.När det gäller mikroplastanalys så är det många olika polymerer i ett stort storleksområde (minst tre tiopotenser), som ska hanteras av samma mätprincip. Det är en stor utmaning i sig och för miljöövervakning finns även önskemål att metoden ska vara enkel, robust och kostnadseffektiv. Detta perspektiv har i projektet sammanvägts med forskningens behov av så heltäckande information som möjligt.För miljöövervakningsbehov har en mätmetod baserad på en ny kortvågsinfraröd hyperspektralkamera utvecklats, med goda preliminära resultat. Metoden kan skilja mikroplast från naturliga partiklar samt i viss mån urskilja olika polymerer från varandra. Nästa steg blir att integrera kameran i ett motoriserat mikroskop.För forskningsbehov har flera olika metoder tagits fram. Inledningsvis har ett nytt nano-platinabelagt filter utvecklats. Sen har infraröd absorptionsspektroskopi (FTIR) utvecklats med avseende på mjukvarukontroll av mikroskop samt bildupptagning och dataanalys med en öppen källkodsmjukvara. Den kan anses vara en mogen analysteknik ner till 10 µm för de flesta polymerer.För mindre partikelstorlekar har fokus legat på vidareutveckling av Ramanspektroskopi, vilket även har utprovats i flera fallstudier för partiklar ner till nanoplastområdet (> 0,5 µm i det här fallet).För vissa specialfall, till exempel båtbottenfärgpartiklar eller däckslitagepartiklar, har det visat sig att varken FTIR eller Raman är särskilt effektiva identifieringsmetoder, men att en kombination av ljus- och svepelektronmikroskopi i korrelativ modalitet kunnat identifiera partiklarna.Provupparbetning är en viktig del för både miljöövervakning och forskning av mikroplastanalys i komplexa prover som sediment, havsvattenbiota, och här har optimerats protokoll för nedbrytning av organiskt material och även apparatur och metod för extraktion av mikroplast från sediment efter nedbrytning av organiskt material.
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| 5. |
- Tagg, A. S., et al.
(författare)
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Agricultural application of microplastic-rich sewage sludge leads to further uncontrolled contamination
- 2022
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 806:4
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Tidskriftsartikel (refereegranskat)abstract
- Municipal sewage sludge has been shown to be high in microplastics (MP) and is applied to agricultural land as fertiliser in many countries. The authors recently proposed in a viewpoint article that MP applied to land in this way may well contaminate other areas in an uncontrolled way. This study examined experimental plots with known history of application of sewage sludge. Results showed that 44% of the MP load found on sludge-applied land was found on nearby land never directly applied with sludge. Examination of polymer type compositions demonstrated marked similarity between the two fields indicating the sludge-applied field was a source of contamination for surrounding areas. Furthermore, MP was detected at a depth of 60–90 cm in the sludge-applied soil indicating that MP may also penetrate deep enough to reach agricultural drainage systems, although this effect is slight (1.6% of surface load). These results show that application of municipal sewage sludge on agricultural land can lead to further uncontrolled contamination, paving the way for future research to improve understanding of the extents of such effects on real farms to better inform future agricultural policy. © 2021
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| 6. |
- Watson, Hunna J., et al.
(författare)
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Common Genetic Variation and Age of Onset of Anorexia Nervosa
- 2022
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Ingår i: BIOLOGICAL PSYCHIATRY: GLOBAL OPEN SCIENCE. - : Elsevier BV. - 2667-1743. ; 2:4, s. 368-378
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Genetics and biology may influence the age of onset of anorexia nervosa (AN). The aims of this study were to determine whether common genetic variation contributes to age of onset of AN and to investigate the genetic associations between age of onset of AN and age at menarche.METHODS: A secondary analysis of the Psychiatric Genomics Consortium genome-wide association study (GWAS) of AN was performed, which included 9335 cases and 31,981 screened controls, all from European ancestries. We conducted GWASs of age of onset, early-onset AN (,13 years), and typical-onset AN, and genetic correlation, genetic risk score, and Mendelian randomization analyses.RESULTS: Two loci were genome-wide significant in the typical-onset AN GWAS. Heritability estimates (single nucleotide polymorphism-h2) were 0.01-0.04 for age of onset, 0.16-0.25 for early-onset AN, and 0.17-0.25 for typical-onset AN. Early-and typical-onset AN showed distinct genetic correlation patterns with putative risk factors for AN. Specifically, early-onset AN was significantly genetically correlated with younger age at menarche, and typical-onset AN was significantly negatively genetically correlated with anthropometric traits. Genetic risk scores for age of onset and early-onset AN estimated from independent GWASs significantly predicted age of onset. Mendelian randomization analysis suggested a causal link between younger age at menarche and early -onset AN.CONCLUSIONS: Our results provide evidence consistent with a common variant genetic basis for age of onset and implicate biological pathways regulating menarche and reproduction.
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