TY - JOUR

T1 - Microplastics effects on wettability, pore sizes and saturated hydraulic conductivity of a loess topsoil

AU - Shafea, Leila

AU - Felde, Vincent J.M.N.L.

AU - Woche, Susanne Karoline

AU - Bachmann, Jörg

AU - Peth, Stephan

N1 - Funding Information: We appreciate the helpful laboratory assistance from the Institute of Materials Engineering, Plastics Technology of Kassel University and Prof. Dr. Hans-Peter Heim, the head of that institute, for their support in microplastic preparation for our experiment.

PY - 2023/9

Y1 - 2023/9

N2 - Environmental contamination with microplastics (MP, 0.1 µm – 5 mm diameter) potentially threatens various soil functions and agricultural production. In this study we evaluated the effects of MP on physical soil parameters (saturated hydraulic conductivity, water retention and water repellency) at MP concentrations (0.5 to 2 % w/w) that have been reported for farmland soils. Polyethylene terephthalate (PET) and polystyrene (PS) of three sizes ranging between 0.5 and 3 mm diameter, were mixed with loess topsoil material from an agriculturally used Luvisol. Results show that increasing MP concentration decreased the saturated hydraulic conductivity (ksat) compared to the control soil (without MP), irrespective of MP type. The highest reduction of ksat was found for the highest concentration (2 %) and the largest size MP (approx. 3 mm diameter). Compared to the control, MP addition significantly decreased soil water retention with increasing concentration. In contrast, air capacity was increased with MP addition where strongest effect was found for largest PET particles at the highest concentration. Soil water repellency (measured as Wilhelmy Plate contact angles) was increased at a concentration of 2 % and for MP sizes > 1 mm, while no effect was observed for lower concentrations and smaller MP. In conclusion, MP type, size, and concentration did affect key soil physical parameters, likely to negatively influence plant growth in contaminated soils.

AB - Environmental contamination with microplastics (MP, 0.1 µm – 5 mm diameter) potentially threatens various soil functions and agricultural production. In this study we evaluated the effects of MP on physical soil parameters (saturated hydraulic conductivity, water retention and water repellency) at MP concentrations (0.5 to 2 % w/w) that have been reported for farmland soils. Polyethylene terephthalate (PET) and polystyrene (PS) of three sizes ranging between 0.5 and 3 mm diameter, were mixed with loess topsoil material from an agriculturally used Luvisol. Results show that increasing MP concentration decreased the saturated hydraulic conductivity (ksat) compared to the control soil (without MP), irrespective of MP type. The highest reduction of ksat was found for the highest concentration (2 %) and the largest size MP (approx. 3 mm diameter). Compared to the control, MP addition significantly decreased soil water retention with increasing concentration. In contrast, air capacity was increased with MP addition where strongest effect was found for largest PET particles at the highest concentration. Soil water repellency (measured as Wilhelmy Plate contact angles) was increased at a concentration of 2 % and for MP sizes > 1 mm, while no effect was observed for lower concentrations and smaller MP. In conclusion, MP type, size, and concentration did affect key soil physical parameters, likely to negatively influence plant growth in contaminated soils.

KW - Hydraulic conductivity

KW - Hydrophobicity

KW - Luvisol

KW - Polyethylene terephthalate

KW - Polystyrene

KW - Soil water retention

UR - http://www.scopus.com/inward/record.url?scp=85162148392&partnerID=8YFLogxK

U2 - 10.1016/j.geoderma.2023.116566

DO - 10.1016/j.geoderma.2023.116566

M3 - Article

AN - SCOPUS:85162148392

VL - 437

JO - GEODERMA

JF - GEODERMA

SN - 0016-7061

M1 - 116566

ER -