Effect of coupled physical and chemical heterogeneity on the transport of pristine and aged pyrogenic carbon colloids in unsaturated porous media

Zhao，Kang1,2; Shang，Jianying1

2024-03-25

10.1016/j.scitotenv.2024.170542

Science of the Total Environment   影响因子和分区

0048-9697

1879-1026

Due to extensive application and recurrent wildfires, an increasing number of pyrogenic carbon (PyC) colloids are present in the environment, experiencing processes of environmental aging. Subsurface environments are typically heterogeneous in unsaturated conditions, which may affect the transport of PyC colloids. This study focused on the transport of both pristine and aged PyC colloids in physically (clean coarse and fine sand) and physicochemically (iron oxides-coated coarse and clean fine sand) heterogeneous porous media at three different water saturations (100 %, 70 %, and 40 %). In physically heterogeneous porous media, the decrease in water saturation from 100 % to 40 % led to a shift in the main water flow from the clean coarse sand to the clean fine sand domain, resulting in a continuous decrease in the transport of PyC colloids. In physicochemically heterogeneous porous media, the primary water flow shifted from the iron oxides-coated coarse sand to the clean fine sand domain, resulting in an initial increase and subsequent decrease in PyC colloid transport. Aging enhanced the transport of PyC colloids, attributed to the increasingly negative and hydrophilic surface. Retention profiles revealed substantial PyC colloid retention at the interface between coarse and fine sand domains. The release of retained PyC colloids exhibited two peaks at 100 % and 70 % water saturations, along with a single peak at 40 % water saturation. Additionally, the increased irreversible retention was observed at lower water saturation. This study underscores the significance of water content, environmental aging, and heterogeneity in PyC colloid transport. It provides essential insights into the environmental fate of PyC colloids in natural field conditions.

Aging Heterogeneity Pyrogenic carbon colloids Transport Unsaturated porous media

SCI ; EI

英语

其他

ENVIRONMENT/ECOLOGY

2-s2.0-85183965308

Scopus

1.College of Land Science and Technology,China Agricultural University,Key Laboratory of Arable Land Conservation in North China,Ministry of Agriculture and Rural Affairs,Beijing,100193,China
2.State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control,School of Environmental Science and Engineering,Southern University of Science and Technology,Shenzhen,518055,China

Zhao，Kang,Shang，Jianying. Effect of coupled physical and chemical heterogeneity on the transport of pristine and aged pyrogenic carbon colloids in unsaturated porous media[J]. Science of the Total Environment,2024,918.

Zhao，Kang,&Shang，Jianying.(2024).Effect of coupled physical and chemical heterogeneity on the transport of pristine and aged pyrogenic carbon colloids in unsaturated porous media.Science of the Total Environment,918.

Zhao，Kang,et al."Effect of coupled physical and chemical heterogeneity on the transport of pristine and aged pyrogenic carbon colloids in unsaturated porous media".Science of the Total Environment 918(2024).