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Bacterial diversity dynamics in sandy loam soils in Tanzania under varying fertilizer-derived uranium concentrations
Mwalongo , Dennis A.; Lisuma, Jacob B.; Haneklaus, Nils H.; Maged, Ali; Brink, Hendrik Gideon; Carvalho , Fernando P.; Wacławek, Stanisław; Mpumi, Nelson; Amasi, Aloyce I.; Mwimanzi , Jerome M.; Chuma, Furaha M.; Kivevele, Thomas T.; Mtei, Kelvin M. (MDPI, 2025-08-13)
The presence of radiotoxic uranium (U) in mineral fertilizers is of global concern. A pilot study was conducted in Tabora (Tanzania) to determine the release of U from three brands of phosphate fertilizers and its impact on soil bacteria. The experiment used three types of fertilizer: Minjingu Powder (MP), Nafaka Plus (NP), a mixed and granulated fertilizer made from Minjingu Phosphate Rock (MPR), and YaraMila Cereal (YC) fertilizer. There was also a control treatment that was not fertilized (NF). Alpha diversity and the R tool were used to analyze bacterial diversity in four samples within an average sequencing depth of 74,466 reads, using metrics like ASVs, Shannon index, and Chao1. The results showed that the number of amplicon sequence variants (ASVs) in the DNA from soil bacteria decreased, specifically to 400 ASVs, in the NP treatment, which was in line with the higher U concentration (3.93 mg kg−1) in the soils. In contrast, the MP fertilizer treatment, associated with a lower U concentration (3.06 mg kg−1) in soils, exhibited an increase in ASVs within the DNA of soil bacteria, reaching 795; the highest ASV value (822) was observed in the NF treatment. Higher amounts of U in the soil plots seemed to have resulted in more types of bacteria, with the Actinobacteriota phylum being the most common in all of the treatments. The NP (3.93 mg kg−3 U concentration) and MP (3.06 mg kg−3 U concentration) treatments were the only ones that showed Halobacteriota and Crenarchaeota phyla. Nonetheless, bacterial diversity may also account for the alterations in soil phosphorus and nitrogen following fertilizer application. The YaraMila Cereal treatment did not seem to be linked to any particular bacterial phylum. This means that in this study it did not have any measurable effect on the soil bacteria species compared to the MP and NP treatments.
Hi gas in the rejuvenated radio galaxy PKS 2014-55
Mtshweni, Leon; Thorat, Kshitij; Deane, Roger; Frank, Bradley S.; Maccagni, Filippo M.; Jozsa, Gyula I.; Cotton, William D.; Giri, Gourab; White, Sarah V.; Atemkeng, Marcellin; Bester, Hertzog L.; Fanaroff, Bernie L.; Heywood, Ian; Lawrie, Graham; Manamela, Thato Eugine; Magolego, Isaac; Mauch, Tom; Oozeer, Nadeem; Smirnov, Oleg; Kupa, Masacheba S. (Oxford University Press, 2025-10)
Please read abstract in the article.
MeerKAT discovery of an infalling cold gas tail on to the nearby barred spiral galaxy, NGC 5643
Santana, Karina C.; Maccagni, Filippo M.; Deane, Roger; Healy, Julia (Oxford University Press, 2025-07)
Please read abstract in the article.
An extended and extremely thin gravitational arc from a lensed compact symmetric object at redshift of 2.059
McKean, John P.; Spingola, C.; Powell, D.M.; Vegetti, S. (Oxford University Press, 2025-11)
Compact symmetric objects (CSOs) are thought to be short-lived radio sources with two lobes of emission that are separated by less than a kpc in projection. However, studies of such systems at high redshift are challenging due to the limited resolution of present-day telescopes, and can be biased to the most luminous objects. Here, we report imaging of a gravitationally lensed CSO at a redshift of 2.059 using very long baseline interferometry at 1.7 GHz. The data are imaged using Bayesian forward modelling deconvolution, which reveals a spectacularly extended and thin gravitational arc, and several resolved features within the lensed images. The surface brightness of the lensing-corrected source shows two mini-lobes separated by 642 pc in projection, with evidence of multiple hotspots that have brightness temperatures of 108 . 6 to 109 . 2 K, and a total luminosity density of 1026 . 3 W Hz−1 . By combining the well-resolved radio source morphology with previous multiwavelength studies, we conclude that this object is likely a CSO of type 2, and that the properties are consistent with the bow-shock model for compact radio sources. Our analysis highlights the importance of combining high-quality data sets with sophisticated imaging and modelling algorithms for studying the high-redshift Universe.
A spatially resolved spectral analysis of giant radio galaxies with MeerKAT
Charlton , K.K.L.; Delhaize, J.; Thorat, Kshitij; Heywood, I.; Jarvis , M.J.; Hardcastle, M.J.; An, F.; Delvecchio, I.; Hale, C.L.; Whittam, I.H.; Bruggen, M.; Marchetti, L.; Morabito, L.; Randriamanakoto, Z.; White, S.V.; Taylor, A.R. (Oxford University Press, 2025)
In this study we report the spatially resolved, wideband spectral properties of three giant radio galaxies (GRGs) in the COSMOS field: MGTC J095959.63 + 024608.6, MGTC J100016.84 + 015133.0, and MGTC J100022.85 + 031520.4. One of these galaxies, MGTC J100022.85 + 031520.4, is reported here for the first time, with a projected linear size of 1.29 Mpc at a redshift of 0.1034. Unlike the other two, it is associated with a brightest cluster galaxy (BCG), making it one of the few GRGs known to inhabit cluster environments. We examine the spectral age distributions of the three GRGs using new MeerKAT UHF-band (544–1088 MHz) observations, and L -band (900–1670 MHz) data from the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) survey. We test two models of spectral ageing, the Jaffe–Perola and Tribble models, using the Broadband Radio Astronomy Tools ( BRATS ) software, and find that they agree well with each other. We estimate the Tribble spectral age for MGTC J095959.63 + 024608.6 as 68 Myr, for MGTC J100016.84 + 015133.0 as 47 Myr, and for MGTC J100022.85 + 031520.4 as 67 Myr. We find significant disagreements between these spectral age estimates and the estimates of the dynamical ages of these GRGs, modelled in cluster and group environments. Our results highlight the need for additional processes that are not accounted for in either the dynamic age or the spectral age estimations.