The bianchetto truffle (Tuber borchii) a lead-resistant ectomycorrhizal fungus increases Quercus cerris phytoremediation potential.

Tuber borchii is a European edible truffle which forms ectomycorrhizas with several soft- and hardwood plants. In this article, the effects of high level of Pb on the in vitro growth of five T. borchii strains and the molecular mechanisms involved in Pb tolerance were studied. Moreover, the effects of the Pb treatment on T. borchii ectomycorrhizas and on the growth, element uptake and distribution in different organs of Quercus cerris seedlings were investigated. The results showed an extraordinary tolerance of T. borchii mycelium to Pb: all the tested strains were able to grow at Pb concentration over 4000 mg L-1 . The mechanisms of tolerance seem related to Pb sequestration in the vacuole and its immobilization as crystal of Pb oxalate outside the hyphae rather than detoxification processes, considering the low expression of glutaredoxin and thioredoxin genes. T. borchii-Q. cerris mycorrhizas tolerate a soil concentration of Pb from 1869 to 4030 mg kg-1 although, at these Pb concentrations, T. borchii showed a reduced ability to colonize roots. T. borchii mycorrhization increased the uptake of Pb by Q. cerris. Mycorrhization and Pb treatment also significantly influenced the uptake and translocation in the plant of other elements.

Translocation of potential toxic elements from soil to black cabbage (Brassica oleracea L.) growing in an abandoned mining district area of the Apuan Alps (Tuscany, Italy).

In the Apuan Alps (Tuscany, Italy), long-lasting mining activities have favored the mobilization of numerous metals present in sulfosalts originated from low-grade metamorphism mineralization. Such materials, rich in potentially toxic elements such as antimony, arsenic, barium, copper, lead, thallium, tin and zinc, represent the substrate on which soils of different thicknesses have been formed and is currently used for agricultural activities. High concern is particularly arising about the food safety due to traditional horticultural practices, since it is very common in this area to cultivate vegetables in private gardens for both self-consuming and/or local market. In this context, a monitoring survey on both soils and vegetables was performed over the area, with particular attention to Brassica oleracea L. as traditional food crop, to assess the degree of contamination of the area, the possible translocation to vegetables and the potential human risk linked to vegetable ingestion. This analysis reveals a different degree of soil contamination in the area and a general high human risk linked to cabbage cultivation and ingestion in the whole area.

Peat Soil Burning in the Mezzano Lowland (Po Plain, Italy): Triggering Mechanisms and Environmental Consequences.

The effects of peat burning on organic-rich agricultural soils of the Mezzano Lowland (NE Italy) were evaluated on soil profiles variously affected by smoldering. Profiles were investigated for pH, electrical conductivity, bulk density, elemental and isotopic composition of distinct carbon (and nitrogen) fractions. The results suggest that the horizons affected by carbon loss lie at depths 10-70 cm, where the highest temperatures are developed. We suggest that the exothermal oxidation of methane (mediated by biological activity) plays a significant role in the triggering mechanism. In the interested soils we estimated a potential loss of Soil Organic Carbon of approximately 110 kg m -2 within the first meter, corresponding to 580 kg CO2 m -3. The released greenhouse gas is coupled with a loss of soil structure and nutrients. Moreover, the process plausibly triggers mobility of metals bound in organometallic complexes. All these consequences negatively affect the environment, the agricultural activities and possibly also health of the local people.

Salt Tolerance and Na Allocation in Sorghum bicolor under Variable Soil and Water Salinity.

Salinity is a major constraint for plant growth in world areas exposed to salinization. Sorghum bicolor (L.) Moench is a species that has received attention for biomass production in saline areas thanks to drought and salinity tolerance. To improve the knowledge in the mechanisms of salt tolerance and sodium allocation to plant organs, a pot experiment was set up. The experimental design combined three levels of soil salinity (0, 3, and 6 dS m-1) with three levels of water salinity (0, 2-4, and 4-8 dS m-1) and two water regimes: no salt leaching (No SL) and salt leaching (SL). This latter regime was carried out with the same three water salinity levels and resulted in average +81% water supply. High soil salinity associated with high water salinity (HSS-HWS) affected plant growth and final dry weight (DW) to a greater extent in No SL (-87% DW) than SL (-42% DW). Additionally, HSS-HWS determined a stronger decrease in leaf water potential and relative water content under No SL than SL. HSS-HWS with No SL resulted in a higher Na bioaccumulation from soil to plant and in translocation from roots to stem and, finally, leaves, which are the most sensitive organ. Higher water availability (SL), although determining higher salt input when associated with HWS, limited Na bioaccumulation, prevented Na translocation to leaves, and enhanced selective absorption of Ca vs. Na. At plant level, higher Na accumulation was associated with lower Ca and Mg accumulation, especially in No SL. This indicates altered ion homeostasis and cation unbalance.

A new paper sensor method for field analysis of acid volatile sulfides in soils.

Monitoring of biogenic sulfide is important because acid volatile sulfides (AVS) represent a reactive pool responsible for immobilization of toxic metals. We propose a new sulfide paper sensor method for semiquantitative determination of AVS in which developed color is compared to a reference chart. The method was validated against the ion-selective microelectrode and the purge-and-trap methods. For fieldwork, readings should fall within 1 to 10 µmoles S2- . Considering that the volume of soil used ranged between 1 and 16 cm3 , the corresponding soil sulfides concentration range spans from 0.06 to 10 mmoles S2- cm-3 . The sulfide paper sensor method is highly suitable for field screening and has sensitivity levels comparable to laboratory methods. Environ Toxicol Chem 2018;37:3025-3031. © 2018 SETAC.

Uptake and translocation of metals and nutrients in tomato grown in soil polluted with metal oxide (CeO2, Fe3O4, SnO2, TiO2) or metallic (Ag, Co, Ni) engineered nanoparticles.

The influence of exposure to engineered nanoparticles (NPs) was studied in tomato plants, grown in a soil and peat mixture and irrigated with metal oxides (CeO2, Fe3O4, SnO2, TiO2) and metallic (Ag, Co, Ni) NPs. The morphological parameters of the tomato organs, the amount of component metals taken up by the tomato plants from NPs added to the soil and the nutrient content in different tomato organs were also investigated. The fate, transport and possible toxicity of different NPs and nutrients in tomato tissues from soils were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). The tomato yield depended on the NPs: Fe3O4-NPs promoted the root growth, while SnO2-NP exposure reduced it (i.e. +152.6 and -63.1 % of dry matter, respectively). The NP component metal mainly accumulated in the tomato roots; however, plants treated with Ag-, Co- and Ni-NPs showed higher concentration of these elements in both above-ground and below-ground organs with respect to the untreated plants, in addition Ag-NPs also contaminated the fruits. Moreover, an imbalance of K translocation was detected in some plants exposed to Ag-, Co- and Fe3O4-NPs. The component metal concentration of soil rhizosphere polluted with NPs significantly increased compared to controls, and NPs were detected in the tissues of the tomato roots using electron microscopy (ESEM-EDS).