Application of New Polymer Soil Amendment in Ecological Restoration of High-Steep Rocky Slope in Seasonally Frozen Soil Areas.

In seasonally frozen soil areas, high-steep rocky slopes resulting from open-pit mining and slope cutting during road construction undergo slow natural restoration, making ecological restoration generally challenging. In order to improve the problems of external soil attachment and long-term vegetation growth in the ecological restoration of high-steep rocky slopes in seasonally frozen areas, this study conducted a series of experiments through the combined application of polyacrylamide (PAM) and carboxymethyl cellulose (CMC) to assess the effects of soil amendments on soil shear strength, water stability, freeze-thaw resistance, erosion resistance, and vegetation growth. This study showed that the addition of PAM-CMC significantly increased the shear resistance and cohesion of the soil, as well as improving the water stability, freeze-thaw resistance, and erosion resistance, but the internal friction angle of the soil was not significantly increased after reaching a certain content. Moderate amounts of PAM-CMC can extend the survival of vegetation, but overuse may cause soil hardening and inhibit vegetation growth by limiting air permeability. It was observed by a scanning electron microscope (SEM) that the gel membrane formed by PAM-CMC helped to "bridge" and bind the soil particles. After discussion and analysis, the optimum application rate of PAM-CMC was 3%, which not only improved the soil structure but also ensured the growth of vegetation in the later stage under the optimum application rate. Field application studies have shown that 3% PAM-CMC-amended soil stably attaches to high-steep rocky slopes, with stable vegetation growth, and continues to grow after five months of freeze-thaw action, with no need for manual maintenance after one year.

Source and health risk assessment of soil polycyclic aromatic hydrocarbons under straw burning condition in Changchun City, China.

Changchun, China is located in one of the world's three golden corn belts. As a key commodity grain base in China, Changchun plays a vital role in providing food security in the northeast. A total of 16 polycyclic aromatic hydrocarbons (PAHs) was analyzed to determine the influence of anthropogenic activities on the environmental quality of agricultural soils under straw burning conditions. The polycyclic aromatic hydrocarbons soil contamination severity was evaluated using the Maliszewska-Kordybach method. The results indicated that the agricultural soils of Changchun are substantial contaminated with PAHs. Petroleum, biomass, and coal combustion are the primary sources of PAH and have been determined using principal component analysis (PCA) and the isomeric ratio approach. The degree of hazard to human health was assessed using toxicity equivalence and increased lifetime cancer risk (ILCR) factors, except in localized areas during adulthood, the general risk was found to be modest. This study provides important information on PAH exposure in agricultural soils in northeast China, and the findings aid in the exploitation of straw and the mitigation of soil environmental concerns, allowing northeast China to achieve green agricultural development.