Opposing Surfactant and Gel Effects of Soil Borne-Hydrogels on Soil Water Retention

Zheng，Wenjuan1; Wang，Lian Ping1; Kuang，Xingxing2; Jin，Yan3; Shen，Chongyang4

2022-11-01

10.1029/2022WR032845

WATER RESOURCES RESEARCH   Impact Factor & Quartile

0043-1397

1944-7973

Soil-borne hydrogels (e.g., bacterial extracellular polymeric substances, root-derived mucilage) contain polymeric (i.e., gel-like) substances as well as surface active substances, which modify the viscosity of soil fluid and wetting properties of soil particles, respectively. In this study, the individual and coupled effects of gel and surfactant on soil water retention were investigated experimentally using xanthan and Triton X-100 as surrogates for gel and surfactant, respectively. Results show opposing effects that xanthan enhanced soil water retention because of increased solution viscosity and its hygroscopic property while surfactant reduced soil water retention due to reduced surface tension. We applied the modified Kosugi model that considers non-capillary adsorption to describe the soil water retention curves measured in this study as well as additional curves reported in the literature. The model effectively captured the gel and surfactant effects using two model parameters, ω and μ, representing the weighting factor for capillary retention and the matric potential required to drain the effective mean pore diameter, respectively. Compared with the controls, gel-dominated samples increased non-capillary adsorption whereas surfactant-dominant samples had a smaller (i.e., less negative) matric potential at the onset of drainage. Finally, we provided an explanation for enhanced water retention due to increased solution viscosity considering fluid displacement process. Our study improved the mechanistic understanding of soil water retention as affected by viscosity and surface tension individually as well as their coupled effects.

soil water retention curve soil-born hydrogels

SCI

English

First

National Natural Science Foundation of China[41907008];National Natural Science Foundation of China[41922047];National Natural Science Foundation of China[91747204];

Environmental Sciences & Ecology ; Marine & Freshwater Biology ; Water Resources

Environmental Sciences ; Limnology ; Water Resources

WOS:000888178400001

AMER GEOPHYSICAL UNION

ENVIRONMENT/ECOLOGY

2-s2.0-85142888261

Scopus

1.Department of Mechanics and Aerospace Engineering,Center for Complex Flows and Soft Matter Research,Southern University of Science and Technology,Shenzhen,China
2.School of Environmental Science and Engineering,Southern University of Science and Technology,Shenzhen,China
3.Department of Plant and Soil Sciences,University of Delaware,Newark,United States
4.Department of Soil and Water Sciences,China Agricultural University,Beijing,China

Zheng，Wenjuan,Wang，Lian Ping,Kuang，Xingxing,et al. Opposing Surfactant and Gel Effects of Soil Borne-Hydrogels on Soil Water Retention[J]. WATER RESOURCES RESEARCH,2022,58(11).

Zheng，Wenjuan,Wang，Lian Ping,Kuang，Xingxing,Jin，Yan,&Shen，Chongyang.(2022).Opposing Surfactant and Gel Effects of Soil Borne-Hydrogels on Soil Water Retention.WATER RESOURCES RESEARCH,58(11).

Zheng，Wenjuan,et al."Opposing Surfactant and Gel Effects of Soil Borne-Hydrogels on Soil Water Retention".WATER RESOURCES RESEARCH 58.11(2022).