Would Forest Litter Cause a Risk of Increased Copper Solubility and Toxicity in Polluted Soils Remediated via Phytostabilization?

Abstract

Soil solutions were collected from soils contaminated differently by the emissions from a copper smelter and incubated with beech litter. Five times in 30 days of incubation, soil solutions were acquired with MacroRhizon samplers and examined using the chemometric approach and two ecotoxicological assays: Microtox with Vibrio fischeri bacteria and Phytotoxkit with Sinapis alba seeds. Copper speciation in soil solutions was modeled in the MinteQ program. Application of beech litter to soils resulted in a considerable increase of copper solubility. The toxicity of soil solutions was associated with total copper concentrations in solutions, copper speciation, and pH values. The toxicity measured by the Phytotoxkit test in soil solutions collected from non-amended soils was higher than that measured in Microtox, and was attributed to high concentrations of copper organic complexes in solutions. The application of beech litter, rich in dissolved organic carbon DOC, resulted in a radical increase of soil solution toxicity to both indicating organisms. This effect, particularly well expressed in the case of V. fischeri, was apparently caused by a decrease in pH and associated increase of total Cu concentrations in solutions.

Transformation of beech forest litter as a factor that triggers arsenic solubility in soils developed on historical mine dumps

“…Similar studies on mine soils were only occasionally performed (Kalbitz and Wennrich 1998; Karczewska et al 2013a;Van Nevel et al 2013Cuske et al 2017) and their results indicated the risk of forest litterinduced release of metals and metalloids from polluted soils.…”

“…Various authors reported increased solubility of heavy metals and arsenic in soils caused by the presence of plant cover or induced by the products that are formed in soils from decomposing plant residues. In particular, the processes of forest litter transformation may lead to increased solubility of various elements, as they deliver organic and inorganic compounds into draining water, stimulate biological activity, and additionally may affect redox conditions (Kalbitz and Wennrich 1998;Karczewska et al 2013aKarczewska et al , 2017Kabała et al 2014;Berg 2017;Cuske et al 2017).…”

Role of Leaf Litter on the Incorporation of Copper-Containing Pesticides into Soils Under Fruit Production: a Review

“…This is very relevant as in systems with a rich and even coverage of leaf litter, water that leaches through this layer can be loaded with DOC, enabling the formation of complexes with metals, mobilizing these contaminants into the lower soil layers (Hesterberg et al 1992). Cuske et al (2017) proved that low molecular DOC produced from litter breakdown can increase Cu solubility in forest soils by forming Cu-DOC complexes; therefore, low molecular DOC can be an important factor to increase solubility and mobility of Cu accumulated in soil litter and in soils of fruit tree systems. On the contrary, Lepp et al (1984) informed soil and litter Cu concentrations in 24-, 14-, and 4-year-old coffee orchards.…”

Enzymatic Activity and Its Relationship with Organic Matter Characterization and Ecotoxicity to Aliivibrio fischeri of Soil Samples Exposed to Tetrabutylphosphonium Bromide

“…The percentage of toxic effect is compared with the control, assuming that an effect below 20% means that the sample is nontoxic. The application of the system of toxicity classification developed by Persoone et al [ 84 ] is often used to assess the ecotoxicity of samples contaminated with various xenobiotics [ 25 , 85 , 86 , 87 , 88 , 89 ]. A number of reports on the use of A. fischeri bacteria and Microtox ® in the assessment of the ecotoxicity of ILs can be found in the literature.…”