Protection and appropriate management of forests is one of the key instruments for climate change adaptation. Soil amendments with biochar have shown to be promising in achieving this goal; however, the evaluation of its long-term effects on forest soils has largely been neglected. To assess the advantages and drawbacks of biochar in forest soils, data from relict charcoal hearths (RCH) can be a potent tool as they show changes in soil properties after up to several hundred years. RCHs can be found in places of former metallurgical hot spots and their presence leaves characteristic formations identifiable on a large scale using laser detection technologies. Forest soils with biochar amendment show an increase in base cations, shift towards more alkaline pH, smaller bulk density and seem to be especially beneficial to hostile environments. Sites with favourable conditions may show little to no improvement or may even be adversely affected. Still, with proper investigation, areas with affordable feedstock materials and poor forest soils-such as spruce monocultures of Central Europe-may benefit from biochar amendments and continue to do so in the long term.

Mining and smelting activities can contaminate soils and affect farming due to high emissions and input of potentially toxic elements (PTE) into the environment. Soils (sampled from two depths) and market vegetables from vegetable gardens located within the vicinity of unconfined slag deposits from decades of mining and smelting activities in Kutná Hora, Czechia were assessed to determine to what extent they pose a health hazard to communities that use these gardens. Pseudo-total As concentrations in the soils exceeded background levels (4.5 mg kg−1) 1.9–93 times, with higher concentrations in the deeper layer. The pseudo-total concentrations of PTE in soils ranked in the order As > Zn > Cd > Pb. Phyto-available concentrations of PTE in soils were relatively low, compared to pseudo-total concentrations. Concentration of As, Cd, Pb and Zn in the vegetables exceeded guideline values, with the highest concentrations found in the fruits of cucumber, peppers, and zucchini. Despite low phyto-available PTE concentrations in soils, all the PTE concentrations in the vegetables surpassed the guidelines set by the Czech Ministry of Health and EU directive, indicating a health hazard to consumers.

No abstract