Effects of Pulp and Na-Bentonite Amendments on the Mobility of Trace Elements, Soil Enzymes Activity and Microbial Parameters under Ex Situ Aided Phytostabilization

Abstract

The objective of this study was to explore the potential use of pulp (by-product) from coffee processing and Na-bentonite (commercial product) for minimizing the environmental risk of Zn, Pb and Cd in soil collected from a former mine and zinc-lead smelter. The effects of soil amendments on the physicochemical properties of soil, the structural and functional diversity of the soil microbiome as well as soil enzymes were investigated. Moreover, biomass of Festuca arundinacea Schreb. (cultivar Asterix) and the uptake of trace elements in plant tissues were studied. The outdoor pot set contained the following soils: control soil (initial), untreated soil (without additives) with grass cultivation and soils treated (with additives) with and without plant development. All of the selected parameters were measured at the beginning of the experiment (t0), after 2 months of chemical stabilization (t2) and at the end of the aided phytostabilization process (t14). The obtained results indicated that both amendments efficiently immobilized the bioavailable fractions of Zn (87–91%) and Cd (70–83%) at t14; however, they were characterized by a lower ability to bind Pb (33–50%). Pulp and Na-bentonite drastically increased the activity of dehydrogenase (70- and 12-fold, respectively) at t14, while the activities of urease, acid and alkaline phosphatases differed significantly depending on the type of material that was added into the soil. Generally, the activities of these enzymes increased; however, the increase was greater for pulp (3.5-6-fold) than for the Na-bentonite treatment (1.3–2.2-fold) as compared to the control. Soil additives significantly influenced the composition and dynamics of the soil microbial biomass over the experiment. At the end, the contribution of microbial groups could be ordered as follows: gram negative bacteria, fungi, gram positive bacteria, actinomycetes regardless of the type of soil enrichment. Conversely, the shift in the functional diversity of the microorganisms in the treated soils mainly resulted from plant cultivation. Meanwhile, the highest biomass of plants at t14 was collected from the soil with Na-bentonite (6.7 g dw-1), while it was much lower in a case of pulp treatment (1.43–1.57 g dw-1). Moreover, the measurements of the heavy metal concentrations in the plant roots and shoots clearly indicated that the plants mainly accumulated metals in the roots but that the accumulation of individual metals depended on the soil additives. The efficiency of the accumulation of Pb, Cd and Zn by the roots was determined to be 124, 100 and 26% higher in the soil that was enriched with Na-bentonite in comparison with the soil that was amended with pulp, respectively. The values of the soil indices (soil fertility, soil quality and soil alteration) confirmed the better improvement of soil functioning after its enrichment with the pulp than in the presence of Na-bentonite.

Phytoremediation Potential of Crop Plants in Countering Nickel Contamination in Carbonation Lime Coming from the Sugar Industry

“…The addition of bentonite may improve phytoremediation outcomes since it reduces both the soluble and bioavailable fractions of Ni due to the capacity of this mineral to adsorb the metal in its external and internal sites, as described by other authors [75,80,81]. As reported in previous work [67], the competition of bentonite adsorption sites with Ni adsorbed on organic matter and the stabilisation of the metal in internal adsorption sites of bentonite could reduce the available concentration of Ni in lime (Figure 1b).…”

Coffee Pulp: An Industrial By-product with Uses in Agriculture, Nutrition and Biotechnology

“…In these cases, increased growth (Senthilkumar et al, 2015), (Osorio et al, 2002) and production (Pagán-Roig et al, 2016), (Senthilkumar et al, 2015) of treated plants, increased biomass (Pagan-Roig et al, 2016;Pagán-Roig et al, 2016;Wasilkowski et al, 2017), increased humic acids and polymerization (Pagán-Roig et al, 2016) have been reported. There was overall improvement in soil fertility and quality (Cervantes et al, 2014(Cervantes et al, , 2015aBetancourt et al, 2016;Wasilkowski et al, 2017), as well as efficient (Pagán-Roig et al, 2016) immobilization of Zn(8)7-91%), Cd(70-83%), and Pb (33-50%) contaminated land (Wasilkowski et al, 2017). Fernández and Cordero, 2005 In addition, the application of an organic fertilizer based on coffee pulp improves the distribution of Trichoderma spp (T. koningii, T. harzidigestoanum and T. longibrachiatum) in soil.…”

“…Coffee pulp has been used to amend and improve soils by composting methods (Betancourt et al, 2016) and inoculating mycorrhizals (Osorio et al, 2002), management of soil treatment cycles (Pagan-Roig et al, 2016;Pagán-Roig et al, 2016) and phytoremediation (Wasilkowski et al, 2017). In these cases, increased growth (Senthilkumar et al, 2015), (Osorio et al, 2002) and production (Pagán-Roig et al, 2016), (Senthilkumar et al, 2015) of treated plants, increased biomass (Pagan-Roig et al, 2016;Pagán-Roig et al, 2016;Wasilkowski et al, 2017), increased humic acids and polymerization (Pagán-Roig et al, 2016) have been reported.…”

“…Coffee pulp has been used to amend and improve soils by composting methods (Betancourt et al, 2016) and inoculating mycorrhizals (Osorio et al, 2002), management of soil treatment cycles (Pagan-Roig et al, 2016;Pagán-Roig et al, 2016) and phytoremediation (Wasilkowski et al, 2017). In these cases, increased growth (Senthilkumar et al, 2015), (Osorio et al, 2002) and production (Pagán-Roig et al, 2016), (Senthilkumar et al, 2015) of treated plants, increased biomass (Pagan-Roig et al, 2016;Pagán-Roig et al, 2016;Wasilkowski et al, 2017), increased humic acids and polymerization (Pagán-Roig et al, 2016) have been reported. There was overall improvement in soil fertility and quality (Cervantes et al, 2014(Cervantes et al, , 2015aBetancourt et al, 2016;Wasilkowski et al, 2017), as well as efficient (Pagán-Roig et al, 2016) immobilization of Zn(8)7-91%), Cd(70-83%), and Pb (33-50%) contaminated land (Wasilkowski et al, 2017).…”

Sewage Sludge Application Enhances the Growth of Corchorus olitorius Plants and Provides a Sustainable Practice for Nutrient Recirculation in Agricultural Soils

“…1), SS organic matter also has beneficial effects on many soil physical properties, including soil porosity and soil aggregation, and the increasing retention and movement of water (Kominko et al 2017). Furthermore, the increase of organic matter in SS-amended soils can reduce the bioavailability of HMs to plants due to the ability of metals to form stable complexes with organic matter (Park et al 2011;Wasilkowski et al 2017).…”