Deashed Wheat-Straw Biochar as a Potential Superabsorbent for Pesticides.

Biochar activation methods have attracted extensive attention due to their great role in improving sorptive properties of carbon-based materials. As a result, chemically modified biochars gained application potential in the purification of soil and water from xenobiotics. This paper describes changes in selected physicochemical properties of high-temperature wheat-straw biochar (BC) upon its deashing. On the pristine and chemically activated biochar (BCd) retention of five pesticides of endocrine disrupting activity (carbaryl, carbofuran, 2,4-D, MCPA and metolachlor) was studied. Deashing resulted in increased sorbent aromaticity and abundance in surface hydroxyl groups. BCd exhibited more developed meso- and microporosity and nearly triple the surface area of BC. Hydrophobic pesticides (metolachlor and carbamates) displayed comparably high (88-98%) and irreversible adsorption on both BCs, due to the pore filling, whereas the hydrophilic and ionic phenoxyacetic acids were weakly and reversibly sorbed on BC (7.3 and 39% of 2,4-D and MCPA dose introduced). Their removal from solution and hence retention on the deashed biochar was nearly total, due to the increased sorbent surface area and interactions of the agrochemicals with unclogged OH groups. The modified biochar has the potential to serve as a superabsorbent, immobilizing organic pollutant of diverse hydrophobicity from water and soil solution.

The status of heavy metals in arable soils of contrasting texture treated by biochar - an experiment from Slovakia.

Worldwide, many soils are impacted by degradation processes, which impose a risk to sustainable food production. There is a pressing need to limit these negative impact constraints to sustain the proper functioning of the soil-biota system and soil productivity. Biochar can be a nature-friendly solution for soil remediation; however, knowledge is incomplete in many aspects in this field, like the potential of biochar and biochar-based products as agents to immobilize toxic substances, including heavy metals (HMs) found in the soil. In this study, we investigated the effect of two biochar substrates (BSs) (1. biochar blended with farmyard manure as BS1, and 2. biochar blended with farmyard manure and digestate as BS2) at rates of 10 and 20 t ha-1 applied without or with fertilization (BS + F) on the immobilization of HMs in texturally different soils (1. sandy Arenosol, 2. loamy Chernozem, Slovakia). The results showed that application of BS had different effects in relation to soil textures. In sandy soil, BS improved soil properties, such as cation exchange capacity (an increase from 20 to 93%), soil organic carbon content (SOC) (an increase from 3 to 26%) and humic substances (HSs) stability (an increase from 12 to 20%). In loamy soil, SOC increased due to BS and BS + F in the range 3-19% and 12-55%, respectively. In both soils, the total content of HMs did not exceed the threshold limits for individual soils after BS and BS + F application. In sandy soil, the immobilization of HMs was due to a higher SOC content and a fulvic acids (FAs) content, while in loamy soil their elimination depended on a higher available phosphorus content.

Accumulation of airborne potentially toxic elements in Pinus sylvestris L. bark collected in three Central European medium-sized cities.

This study attempts to identify the influence of various aspects of human activities in three medium-sized Central European cities (Cottbus, Germany; Nitra, Slovakia and Slupsk, Poland) on air contamination. For comparison purposes, bark of Pinus sylvestris L. was collected from polluted and non-polluted urban areas. Nine elements: Fe, Mn, Cu, Zn, Ni, Cd, Cr, Pb and S were determined using microwave plasma atomic emission spectrometry, flame atomic absorption spectrometry and elementary analyzer. Results of the study showed significant differences between the cities in term of elements content in pine bark. The differences reflected well specific character of the cities and various effects of human activity. Study revealed that elements spatial variability among the cities is driven by the factor loadings character and reflects various emission sources and their impact range.

Nanogold Biosynthesis Mediated by Mixed Flower Pollen Grains.

Physical and chemical methods for nanoparticle synthesis are disadvantageous to less energy demanding and more efficient and environmentally friendly biological approaches. Thus, in this paper, we designed simple, bottom-up, in vitro, static experiment under laboratory conditions using suspension of mixed flower pollen grains for nanoparticle synthesis. Pollen grains provided template substrates for gold nanoparticles synthesis from dissolved Au(III). Transmission and scanning electron microscopy along with ultraviolet-visible spectra confirmed the gold nanoparticles formation. The biosynthesized/phytosynthesized gold nanoparticles had relative narrow size distribution (from 3 to 11 nm) with dominant spherical morphology with no aggregated forms. Thus, the gold nanoparticles in pollen dispersion provides excellent stability and dispersity.