Summary: Root citrate exudation is thought to be important for phosphate solubilization. Previous research has concluded that cluster‐like roots benefit most from this exudation in terms of increased phosphate uptake, suggesting that root structure plays an important role in citrate‐enhanced uptake (additional phosphate uptake due to citrate exudation). Time‐resolved computed tomography images of wheat root systems were used as the geometry for 3D citrate‐phosphate solubilization models. Citrate‐enhanced uptake was correlated with morphological measures of the root systems to determine which had the most benefit. A large variation of citrate‐enhanced uptake over 11 root structures was observed. Root surface area dominated absolute phosphate uptake, but did not explain citrate‐enhanced uptake. Number of exuding root tips correlated well with citrate‐enhanced uptake. Root tips in close proximity could collectively exude high amounts of citrate, resulting in a delayed spike in citrate‐enhanced uptake. Root system architecture plays an important role in citrate‐enhanced uptake. Singular morphological measurements of the root systems cannot entirely explain variations in citrate‐enhanced uptake. Root systems with many tips would benefit greatly from citrate exudation. Quantifying citrate‐enhanced uptake experimentally is difficult as variations in root surface area would overwhelm citrate benefits.

We present a survey on the environmental contamination of the Alviano Lake territory (Central Italy) based on Apis mellifera ligustica samples collected in two annual samplings (2019–2020). Concentrations of 30 elements were determined in the whole bees, in the gaster, and in the body without the gaster. The study generally revealed a low level of contamination of the bee tissues. However, As showed higher concentrations than in other rural areas, although lower than in samples from urban and productive areas. On the other hand, despite the environmental context, Hg showed limited contamination levels, with the exception of a single sample. Elemental analysis along the longitudinal axis of the bees’ bodies showed greater and statistically significant presences of V, Al, Be, Pb, Cd, Co, Mn, Ba, and Sr in the gaster. The only exceptions concerned As and S (and to a lesser extent Hg), with higher concentrations found in the body without the gaster. We hypothesise that this selectivity maybe due to the affinity of these elements with S, which is abundant in the proteins of the flight muscles in the insect thorax, which are rich in amino acids containing the –SH group.

In this work, we have characterized the iron local structure in samples of two different types of atmospheric dust using X-ray absorption spectroscopy and selective leaching experiments. Specifically, we have investigated samples of long-range transported Saharan dust and freshly emitted steel plant fumes with the aim of individuating possible fingerprints of iron in the two cases. Findings include (1) prevalence of octahedral coordinated Fe ${}^{3+}$ for all samples; (2) presence of 6-fold coordinated Fe ${}^{3+}$ , aluminosilicates and iron oxy(hydr)oxides in Saharan dust and (3) of Fe-bearing spinel-like structures in the industrial fumes; (4) general predominance of the residual insoluble fraction with a notable difference: 69% for Saharan dust and 93% for steel production emissions, associated with aluminosilicates and non-reducible iron oxy(hydr)oxides, and Fe spinels, respectively. The remarkable differences between the X-ray absorption spectroscopy (XAS) spectra and leaching test results for the two sample types suggest the possibility to exploit the present approach in more complex cases. To this aim, two additional case studies of mixed aerosol samples are presented and discussed.