Feasibility assessment of bentonite drilling mud to improve the physical quality of loamy sand soil and water deficit of forest plant seedlings.

Spent drilling mud (DM), a co-product during horizontal directional drilling operations, needs proper disposal to comply with social and environmental sustainability awareness, with one option being its cost-effective reuse as a soil amendment. The possibility was investigated of DM applications to improve the physical quality of loamy sand soil. The soil was treated with increasing DM contents in a laboratory at volumetric DM-to-soil ratios of 0:100 (DM0, no DM), 25:75 (DM25), 50:50 (DM50), 75:25 (DM75), and 100:0 (DM100, no soil).

Sulfur amendments to soil decrease inorganic arsenic accumulation in rice grain under flooded and nonflooded conditions: Insights from temporal dynamics of porewater chemistry and solid-phase arsenic solubility.

Rice cultivation under flooded conditions enhances arsenic (As) solubility and favors As accumulation in rice grain that poses an indisputable threat to human health worldwide. The reduction of sulfur may induce processes that decrease As solubility, but its impact on rice grain As species remains unresolved. Herein, we investigated the influence of sulfur (S)-containing materials, including chicken manure and elemental sulfur powder on As accumulation and speciation in rice grain as well as the dynamics of the porewater chemistry and solid-phase As solubility throughout the entire growth stage under continuous flooding and intermittent flooding conditions in pot experiments.

Biochar and ash derived from silicon-rich rice husk decrease inorganic arsenic species in rice grain.

Exposure to arsenic (As) through rice consumption potentially threatens millions of people worldwide. Understanding is still lacking the recycling impacts of rice residues on As phytoavailability in paddy soils and is of indisputable importance in providing a sustainable and effective measure to decrease As accumulation in rice grain. Herein, we examined the effects of rice husk biochar (RHB) and rice husk ash (RHA) on As grain speciation, and As dynamics in the soil porewater and solid-phase fractions.

Transport of barrel and spherical shaped colloids in unsaturated porous media.

Model colloids are usually spherical, but natural colloids have irregular geometries. Transport experiments of spherical colloids may not reflect the transport characteristics of natural colloids in porous media. We investigated saturated and unsaturated transport of colloids with spherical and angular shapes under steady-state, flow conditions.

Colloid mobilization and transport during capillary fringe fluctuations.

Capillary fringe fluctuations due to changing water tables lead to displacement of air-water interfaces in soils and sediments. These moving air-water interfaces can mobilize colloids. We visualized colloids interacting with moving air-water interfaces during capillary fringe fluctuations by confocal microscopy.

Does colloid shape affect detachment of colloids by a moving air-water interface?

Air-water interfaces interact strongly with colloidal particles by capillary forces. The magnitude of the interaction force depends on, among other things, the particle shape. Here, we investigate the effects of particle shape on colloid detachment by a moving air-water interface.

Detachment of deposited colloids by advancing and receding air-water interfaces.

Moving air-water interfaces can detach colloidal particles from stationary surfaces. The objective of this study was to quantify the effects of advancing and receding air-water interfaces on colloid detachment as a function of interface velocity. We deposited fluorescent, negatively charged, carboxylate-modified polystyrene colloids (diameter of 1 μm) into a cylindrical glass channel.