Co-impacts of cation type and humic acid on migration of polystyrene microplastics in saturated porous media.

The aging process of microplastics (MPs) could significantly change their physical and chemical characteristics and impact their migration behavior in soil. However, the complex effects of different cations and humic acids (HA) on the migration of aged MPs through saturated media are not clear. In this research, the migration and retention of pristine/aged PSMPs (polystyrene microplastics) under combined effects of cations (Na, Ca) (ionic strength = 10 mM) and HA (0, 5, 15 mg/L) were investigated and analyzed in conjunction with the two-site kinetic retention model and DLVO theory.

Effects of solution chemistry and humic acid on transport and deposition of aged microplastics in unsaturated porous media.

Microplastics (MPs) are susceptible to aging in the environment, and aged MPs are highly migratory in soil due to their smaller particle size and more negative surface charge, but the effects of soil environmental factors on the fate and transport of aged MPs are still unclear. In this study, the transport behavior of pristine/aged MPs in unsaturated sandy porous media was examined under different ionic strength (IS), cationic type (Na, Ca) and humic acid (HA) conditions. The results indicated that the surface charge, surface oxygen-containing functional groups and surface morphology of MPs changed significantly after aging, and that the mobility of aged MPs was significantly enhanced than the pristine MPs under all test conditions.

Transport characteristics of polystyrene microplastics in saturated porous media with biochar/FeO-biochar under various chemical conditions.

Magnetically modified biochar, with a rougher surface and more positive surface charge, may interact with microplastics (MPs) after being applied to soil, potentially altering the fate and transport of MPs in porous media. In this study, the transport and retention behavior of polystyrene microplastics (PSMPs) in a sandy porous media mixed with biochar/FeO modified biochar (FeO-biochar) was investigated under various chemical conditions (humic acid (HA), ionic strength (IS) and cationic types (Na/Ca)). The results showed that the addition of biochar and FeO-biochar can hinder the transport of PSMPs in porous media without HA, and that FeO-biochar was more effective in inhibiting the transport of PSMPs through electrostatic adsorption and complexation, with an optimum retention efficiency of 92.

Development of chitosan-magnetic sawdust hydrochar for Pb and Zn immobilization process on various soil conditions.

A series of 60-day soil immobilized incubations were performed to explore the impacts of various factors (incubation time, chitosan modified magnetic sawdust hydrochar (CMSH) dosages, initial pH values, moisture contents, and humic acid (HA)) on CMSH immobilization of Pb and Zn. DTPA and BCR extraction techniques were undertaken to study the distribution of form transformations of Pb and Zn. CMSH showed significant immobilization ability for both DTPA-Pb and DTPA-Zn, and the highest removal rates were shown to be 57.

Organics composition and microbial analysis reveal the different roles of biochar and hydrochar in affecting methane oxidation from paddy soil.

Biochar and hydrochar, as valuable and eco-friendly soil remediation materials from greenwaste, have potential to enhance methane oxidation in paddy soil. But the mechanism of biomass carbon on the improvement of methane-oxidizing bacteria communities in paddy soil has not been adequately elucidated. In the present study, the effect of different-temperature rice straw-based biomass carbon (RB400, RB600, RH250 and RH300) on methane oxidation were investigated by analyzing the soil dissolved organic matter (DOM), physicochemical properties and changes in microbial community structure.

Immobilization of Cd and Pb in soil facilitated by magnetic biochar: metal speciation and microbial community evolution.

The preparation of magnetic biochar from sewage sludge and rice straw for heavy metal contaminated soil remediation has greater application prospects, but its remediation mechanism was rarely considered by combining soil physicochemical properties with microbial community. In this study, the effects of magnetic sewage sludge biochar (SSB) and rice straw biochar (RSB) on Cd and Pb immobilization in paddy soil were compared and analyzed by 60-day soil incubation experiments. The results illustrated that DTPA-Cd and DTPA-Pb were reduced by 51.

Transport and retention of microplastics in saturated porous media with peanut shell biochar (PSB) and MgO-PSB amendment: Co-effects of cations and humic acid.

Biochar particles are extensively used in soil remediation and interact with microplastics (MPs), especially metal oxide-modified biochar may have stronger interactions with MPs. The mechanism of interactions between humic acid (HA) and different valence cations is different and the co-effect on the transport of MPs is not clear. In this study, the co-effects of HA and cations (Na, Ca) on the transport and retention of MPs in saturated porous media with peanut shell biochar (PSB) and MgO-modified PSB (MgO-PSB) were systematically investigated.