Spatial Distribution of Trophic Groups of Amoebae Around the Root Zone of Zea Mays Mycorrhizal With Rhizophagus Intraradices Grown in Microcosms

Fitness and productivity of most terrestrial plants depend on early associations with arbuscular mycorrhizal fungi and mutualistic bacteria. Plants select most of the microbial communities cohabiting their roots and mycorrhizosphere, attracting also all types of microbial predators. Naked amoebae are among the most voracious predators inflicting significant changes in soils bacterial and fungal populations. We evaluated how roots of Zea mays with or without Rhizophagus intraradices mycorrhizosphere (AMF) influence trophic groups of amoebae, along vertical (3, 6, and 9-cm) and horizontal soil distribution (roots and free-root compartments) grown in microcosms after, 20 days. Amoebae community in Non-AMF showed a high species richness in the root zone at 3 to 6-cm depth, and at the two free-root compartment away from plants. Conversely, AMF and mycelium zones modified the amoeba community at 6 to 9-cm depth, recording higher diversity of trophic groups than unplanted soil compartments. The highest bacterivorous diversity was found at the closer compartment to AMF roots, but fungivorous amoebae was not recorded. Amoebae feeding preferences were similar in both AMF and Non-AMF microcosms in where bacterivorous amoebae were dominant, while protozoa-eating amoebae were more frequent at the mycelium compartments. Rare amoebae species were found in AMF microcosms in comparison to those recorded from Non-AMF and unplanted microcosms.

Accumulation and Distribution of Rare Earth Elements (REEs) and Non-REEs With Vetiver Grass in The Abandoned Ion-Absorbed Rare Earth Mine

Overexploitation of rare earth elements (REEs) has caused serious desertification and environmental pollution, and ecological restoration of mines has attracted increasing national attention. In this paper, experiments involved land plowing, organic fertilizer broadcasting and vetiver cultivation were carried out to repair abandoned ion-absorbed rare earth mines (REM). Toxic metals content and pH in mining soil, distribution and transportation of toxic metals in the soil – vetiver grass system were investigated in detail.Results revealed that the abandoned REM soil was weakly acidic (pH=4.09) and rich in various toxic metals composed of REEs (La, Ce, Nd, Y, Gd, Dy) of 657.57mg/kg and Non-REEs (Pb, Cu, Se, As, Cd) of 109.98mg/kg. The distribution pattern in vetiver grass illustrated that toxic metals accumulation was mainly concentrated in the roots instead of shoot, and then the cumulative concentration of REEs in roots were much greater than that of Non-REEs. Furthermore, vetiver grass exhibited preferential accumulation of Cd, Se and REEs during the absorption process (from soil to root) and preferential accumulation of Pb, Cu and As during the translocation process (from root to leaf). The adsorption behavior of toxic metals by vetiver was confirmed due to these observed irregular particles in the scanning electron microscopy.

Distribution of archaeological material scatters and soils at the site of Abila of the Decapolis, northern Jordan

<p>Patterns and intensities of past land use are mostly unknown. However, soils in the vicinity of archaeological sites usually carry significant amounts of material culture (mostly pottery sherds) which testify to past human activity. We surveyed surface transects of material culture and soil distribution, radiating from the city center of ancient Abila of the Decapolis. The city had been abandoned during the Medieval and was never resettled, which minimizes the presence of material culture from younger periods. In addition, earlier studies suggested that soil erosion of the rather level limestone plateau surrounding the site was rather limited, indicating that actual land surfaces largely represent those of antiquity. Our survey encountered strongly varying quantities of material culture, which correspond to some soil properties such as concentrations of faeces biomarkers of pork excrements. As the material culture mainly dates to Late Antiquity, and as pork consumption during the Islamic periods is rather unlikely, this indicates that the distribution of the archaeological material was to some degree connected with pig breeding during Antiquity. A possible practice leading to sherd deposition on fields could be manuring, such as from applying dung including pork excrements, but ratios of N-isotopes do not suggest that fields surrounding Abila were subject to application of larger amounts of manure. Therefore, it seems very likely that material culture deposition on the land surrounding Abila was partly connected with the herding of pigs, a land use practice that is attested in Biblical sources on the region.</p>

Photoperiod shapes aluminium tolerance in plants

Aluminium is a limiting factor for crop productivity in acidic soils (pH ≤ 5.5). Since acid soil distribution on Earth cannot adequately explain the differential Al tolerance across the plant kingdom, we investigated photoperiod effects on plant Al tolerance. We observed that with increasing distance from the equator, Al tolerance disappears, suggesting a relationship with the photoperiod. Long-day (LD) species are generally more Al-sensitive than short-day (SD) species, whereas genetic conversion of tomato for SD growth boosts Al tolerance. Reduced Al tolerance correlates with DNA-checkpoint activation under LD. DNA-checkpoint-related genes are under positive selection in Arabidopsis accessions from regions with shorter days, suggesting photoperiod acts as a selective barrier for Al tolerance. Our findings revealed that diel regulation and genetic diversity affect Al tolerance, suggesting that day-length orchestrates Al tolerance.One-Sentence SummaryAluminum is a major constraint for crop yield worldwide. We reveal that photoperiod acts as a barrier for Al tolerance in plants.

Correlation between Geochemical and Multispectral Patterns in an Area Severely Contaminated by Former Hg-As Mining

In the context of soil pollution, plants suffer stress when exposed to extreme concentrations of potentially toxic elements (PTEs). The alterations to the plants caused by such stressors can be monitored by multispectral imagery in the form of vegetation indices, which can inform pollution management strategies. Here we combined geochemistry and remote sensing techniques to offer a preliminary soil pollution assessment of a vast abandoned spoil heap in the surroundings of La Soterraña mining site (Asturias, Spain). To study the soil distribution of the PTEs over time, twenty-seven soil samples were randomly collected downstream of and around the main spoil heap. Furthermore, the area was covered by an unmanned aerial vehicle (UAV) carrying a high-resolution multispectral camera with four bands (red, green, red-edge and near infrared). Multielement analysis revealed mercury and arsenic as principal pollutants. Two indices (from a database containing up to 55 indices) offered a proper correlation with the concentration of PTEs. These were: CARI2, presenting a Pearson Coefficient (PC) of 0.89 for concentrations >200 mg/kg of As; and NDVIg, PC of −0.67 for >40 mg/kg of Hg. The combined approach helps prediction of those areas susceptible to greatest pollution, thus reducing the costs of geochemical campaigns.