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Microplastic abundance in the environment has been concerning thus there is a need to understand their pathways and rates for fragmentation and degradation in the environment. However, studies that provide data on rates in a systematic approach differentiating the rates related to specific degradation stressors is limited, and often confound multiple stressors. In this study we aim to address fragmentation and degradation of microplastics by stressing plastics with varying resiliency under different environmental conditions (LDPE, PP, HIPS, PU, PET, PLA, and PA). Using ISO4892, we subject microplastic powder at homogeneous UV intensity to varying exposure time, temperatures and relative humidity conditions. An adaptation of the OECD Hydrolysis Guideline (OECD Test No. 111) is also used to observe fragmentation and degradation of the microplastic powder over time under different pH, salinity, and temperature. To assess the pathways and quantify the rates, multiple analytics are utilized. The NanoRelease protocol, ISO22293:2020, was adapted to quantify the smallest fragments, 10nm to 1µm, thus allowing to show micro- to nano-plastic fragmentation. Chemical degradation is assessed via ATR-FTIR, TOC, and GPC analysis. In addition, microplastic fragments between 1-100 µm are analyzed with a particle counter. Preliminary results following two UV stresses show that HIPS and LDPE had the largest fragmentation with large particle counts in the size class of 1 and 2 µm while PP was most resilient with little to no fragmentation at these size classes. PP also had small changes in its Carbonyl Index whereas TPU and HIPS had the largest changes over UV exposure time. These information on fragmentation and chemical degradation per exposure allows rates to be developed for each polymer which can be implemented into models to understand and predict microplastic fragmentation in different environmental compartments. This is the ultimate goal of our collaborative project "cefic LRI ECO59, FRAGMENT-MNP". Also see: https://micro2022.sciencesconf.org/427037/document, In MICRO 2022, Online Atlas Edition: Plastic Pollution from MACRO to nano

Application of wood ash to forests can restore pools of phosphorus (P) and other nutrients, which are removed following whole tree harvesting. Yet, the mechanisms that affect the fate of ash-P in the organic layer are less well known. Previous research into the extent to which ash application leads to increased P solubility in the soil is contradictory. We combined synchrotron P K-edge XANES spectroscopy, mu-XRF microscopy, and chemical ex-tractions to examine the speciation and solubility of P. We studied organic horizons of two long-term field ex-periments, Riddarhyttan (central Sweden), which had received 3, 6, and 9 Mg ash ha -1, and Ro center dot dalund (northern Sweden), where 3 Mg ash ha- 1 had been applied alone or combined with N every-three years since 2003. At the latter site, we also determined P in aboveground tree biomass. Overall, the ash application increased P in the organic layer by between 6 and 28 kg P ha -1, equivalent to 17-39 % of the initial P content in the applied ash. At Ro center dot dalund, there was 4.6 kg Ca-bound P ha- 1 (9.5 %) in the ash treatment compared to 1.6 kg ha- 1 in the ash + N treatment and < 0.4 kg ha- 1 in the N treatment and the control. At Riddarhyttan, only the treatment with the highest ash dose had residual Ca-bound P (3.8 kg ha -1). In contrast, the ash application increased Al-bound P (p < 0.001) with up to 15.6 kg P ha -1. Moreover, the ash increased Olsen-P by up to two times. There was a strong relationship between the concentrations of Olsen-P and Al-bound P (R2 = 0.83, p < 0.001) as well as Fe-bound P (R2 = 0.74, p = 0.003), suggesting that the ash application resulted in an increased amount of relatively soluble P associated with hydroxy-Al and hydroxy-Fe compounds. Further, there was an 18 % increase in P uptake by trees in the ash treatment. By contrast, repeated N fertilization, with or without ash, reduced Olsen-P. The lower P extractability was concomitant with a 39 % increase in plant P uptake in the N treatment, which indicates elevated P uptake in response to higher N availability. Hence, the application of wood ash increased Al-bound P, easily available P, and P uptake. N fertilization, while also increasing tree P uptake, instead decreased easily available P and did not cause a shift in soil P speciation.

Recent advances in soil phosphorus (P) studies have revealed unique P hot spots and discrete micron-sized grains at soil microsites, but the significance of these so-called 'hot spots' and grains in P cycling and long-term supply is yet to be determined. We examined soil particles and pore space distribution at a micro-scale in two postglacial forest soils by laser ablation ICP-MS imaging. This allowed us to semi-quantitatively reveal both axial and lateral abundance, distribution, and co-localization of P with elements known to influence its chemical speciation (e.g., Si, Al, Mn, Ca, and Fe). The results show topsoil P to be co-localised predominantly with Si, Al, and Fe. However, in the subsoils, P was co-localised mainly with Ca, Si, Al, and Mg in spots within Si and Al-bearing minerals and with only Ca in discrete micron-sized grains. While the spots of P-Ca inclusions were similar to 1000 mu m apart and present at 40-100 cm depth in Tarnsjo, the discrete grains of P-Ca were similar to 700-1200 mu m apart and present at 90-100 cm depth in Tonnersjoheden. The P concentrations in these 'hot spots' and grains were 7 to 600 times greater than the average soil P concentrations, with the highest values (3434-8716 mmol P kg(-1)) occurring in the C horizons of the two soils. When combined with previous P speciation results obtained by synchrotron P K-edge XANES in the same soils, our work confirms geogenic apatite to have been dissolved in the topsoil and its P transformed to P adsorbed by Al-Si and Fe phases, and to organic P. Most importantly, our work shows subsoil spots of P-Ca inclusions and micron-sized grains to be a long-term source of P and Ca. Highlights The significance of high-P spots and discrete grains to long-term P supply is largely unknown. For the first time, P concentration and speciation was resolved by LA-ICP-MS multi-elemental analysis. The P spots exist as dispersed apatite inclusions and micron-sized grains in the subsoil. P in these spots and grains were up to 600 times greater than the bulk soil P concentrations.

The molecular speciation of phosphorus (P) in forest soils is of strategic importance for sustainable forest management. However, only limited information exists about soil P speciation in boreal forests. We combined P K-edge XANES spectroscopy, wet chemical P extractions, and X-ray diffraction analysis of soil minerals to investigate the vertical distribution of P species in seven podzolised forest soils differing in soil properties and climatic conditions. The results showed that the total P stock was on average, 4.0 g m(-2) in the Oe horizon, 9.5 g m(-2) in the A and E horizons, and substantially higher (117.5 g m(-2), and 109.3 g m(-2)) in the B and C horizons down to 80 cm depth, respectively. Although the Oe horizons contain a minor total P stock, 87% of it was stored as organic P. The composition of P species in the P-depleted A/E horizons was highly variable depending on the site. However, of the P stored in B and C horizons down to 80 cm, 58% was adsorbed P, mostly to Al, while apatite accounted for 25% of P, most of which was found in the C horizons. The apatite stocks in the A/E, B, and C horizons (down to 80 cm) accounted for 2.5%, 20%, and 77.2%, respectively, of the total apatite for all the mineral soils studied. These figures can be explained, first, by the dissolution of primary mineral apatite caused mainly by acidification. Second, P uptake by plants and microorganisms, and the associated formation of the Oe horizons, led to the formation of soil organic P. Further, the formation of organo-metal complexes and podzolization led to the translocation of P to the B horizons, where P accumulated mostly as P adsorbed to imogolite-type materials (e.g. allophane) and ferrihydrite, as shown by P K-edge XANES spectroscopy. In conclusion, this study shows that despite the young age of these soils (

In this poster, we describe the FRAGMENT-MNP project, which aims to develop and deliver a pragmatic open-source mechanistic model of how environmental factors affect plastic fragmentation and degradation rates. The poster was presented at the 22nd Annual Workshop of the European Chemical Industry Council Long-Range Research Initiative (Cefic-LRI) on 8-9 November 2021 in Brussels, Belgium.

The cycling and long-term supply of phosphorus (P) in soils are of global environmental and agricultural concern. To advance the knowledge, a detailed understanding of both the vertical and lateral variation of P chemical speciation and retention mechanism(s) is required, a knowledge that is limited in postglacial forest soils. We combined the use of synchrotron X-ray fluorescence microscopy with multi-elemental co-localisation analysis and P K-edge XANES spectroscopy to reveal critical chemical and structural soil properties. We established a two-dimensional (2D) imagery of P retention and speciation at a microscale spatial resolution in two forest soil profiles formed in glaciofluvial and wave-washed sand. The abundance and speciation of P in the upper 40 cm was found to be influenced by soil weathering and podzolization, leading to spatial variability in P speciation on the microscale (< 200 pm) with P existing predominantly as organic P and as PO4 adsorbed to allophane and ferrihydrite, according to XANES spectroscopy. These species were mostly retained at sharp edges and in pore spaces within Al and Si-bearing particles. Despite the relatively young age ( < 15,000 years) of the soils, our results show primary mineral apatite to have weathered from the surface horizons. In the C horizon however, a large fraction of the P was in the form of apatite, which appeared as widely dispersed ( > 600 pm) hot spots of inclusions in aluminosilicates or as discrete micro-sized apatite grains. The subsoil apatite represents a pool of P that trees can potentially acquire and thus add to the biogeochemically active P pool in temperate forest soils.