Sawdust, a cheap by-product of the timber and forestry industry, was considered as a framework structure to prepare superabsorbent polymer with acrylic acid (AA) and acrylamide (AM), the synthetic monomers. The effects of initiator content, crosslinker content, AA content, AM content, degree of neutralization of AA, and reaction temperature on the swelling rate of superabsorbent polymer were investigated. The synthesized polymer was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Under optimal synthesis conditions, the results showed that the swelling rate of the polymer in deionized water and 0.9% NaCl solution reached 738.12 and 90.18 g/g, respectively. The polymer exhibits excellent swelling ability, thermal stability, and reusability. After the polymer was introduced into the samples (soil or coal), the water evaporation rate of the samples was significantly reduced, and the saturated water holding capacity and pore structure were also significantly improved.

Water resources are scarce, and secondary soil salinization is severe in the Hetao Irrigation District. Farmland shelterbelt systems (FSS) play a critical role in regulating soil water and salt dynamics within the irrigation district. However, the understanding of soil water and salt migration within FSS during the freeze–thaw period remains unclear due to the complex and multifaceted interactions between water and salt. This study focused on a typical FSS and conducted comprehensive monitoring of soil moisture, salinity, temperature, and meteorological parameters during the freeze–thaw period. The results revealed consistent trends in air temperature and soil temperature overall. Soil freezing durations exceeded thawing durations, and both decreased with an increasing soil depth. At the three critical freeze–thaw nodes, the soil moisture content at a 0–20 cm depth was significantly lower than at a 40–100 cm depth (p < 0.05). The soil water content increased with time and depth at varying distances from the shelterbelt, with an average increase of 7.63% after freezing and thawing. The surface water content at the forest edge (0.3H, 4H) was lower than inside the farmland (1H, 2H, 3H). Soil salt accumulation occurred during both freezing stable periods and melting–thawing periods in the 0–100 cm soil layer near the forest edge (0.3H, 4H), with the highest soil salinity reaching 0.62 g·kg⁻¹. After the freeze–thaw period, the soil salt content in each layer increased by 11.41–47.26% compared to before the freeze–thaw period. Salt accumulation in farmland soil near the shelterbelt was stronger than in the far shelterbelt. The multivariate statistical model demonstrated goodness of fit for soil water and salt as 0.94 and 0.72, respectively, while the BP neural network model showed goodness of fit for soil water and salt as 0.82 and 0.85, respectively. Our results provide an efficient theoretical basis for FSS construction and agricultural water management practices.

Intercropping systems reduce ineffective evaporation between trees but also intensify interspecific competition and reduce productivity. To improve the water-use efficiency and the economic benefits of an intercropping system on the Loess Plateau, China, where rainfall is limited and evaporation intense, an apple–soybean intercropping system with micro-irrigation water control was adopted to analyze the soil water, root density, water-use efficiency, yield, and economic benefits of intercropping under different micro-irrigation methods. Subsurface seepage irrigation, bubbler irrigation, and drip irrigation under mulching were used with irrigation upper limit levels of three maximum irrigation levels [60% (W1), 75% (W2), and 90% (W3) of field capacity (FC)]. Rainwater harvesting from ridges and furrows (GL) without irrigation was the control. Bubbler irrigation increased the soil water content, optimized the vertical soil water distribution, and promoted root growth. Except for the control treatment (GL), the other micro-irrigation treatments increased with the irrigation amount, but the water-use efficiency decreased. Drip irrigation under mulch combined with W2 (75% Fc) irrigation could obtain the maximum intercropping yield, which was increased by 71.1% compared with the GL treatment. Drip irrigation under a mulch combined with W2 produced the maximum intercropping yield; the economic benefits were higher under drip irrigation with mulching combined with W1; and all three micro-irrigation methods combined with W2 improved the economic benefits by 52.1–115.5% compared to GL. Drip irrigation under mulching or bubbler irrigation combined with W2 should be used when there are sufficient water resources, but drip irrigation under a mulch combined with W1 when there is a water shortage.

The coupling effects of sandstorm and dust from coal bases themselves can have a major impact on the atmospheric environment as well as on human health. The typical coal resource city of Wuhai in Inner Mongolia was selected in order to study these impacts during a severe sandstorm event in March 2021. Particulate matter (PM₁, PM_2.5 and PM₁₀) and total suspended particulate matter (TSP) samples were collected during the sandstorm event of 15–19 March 2021 and non-sandstorm weather (11–13 March 2021) and analyzed for their chemical composition. The concentrations of PM₁, PM_2.5, PM₁₀ and TSP in Wuhai city during the sandstorm were 2.2, 2.6, 4.8 and 6.0 times higher than during non-sandstorm days, respectively. Trace metals concentrations in particles of different sizes generally increased during the sandstorm, while water-soluble ions decreased. Positive matrix fraction (PMF) results showed that the main sources of particles during both sandstorm and non-sandstorm days were industrial emissions, traffic emissions, combustion sources and dust. The proportion of industrial emissions and combustion sources increased compared with non-sandstorm days, while traffic emissions and dust decreased. The backward trajectory analysis results showed that airflows were mainly transported over short distances during non-sandstorm days, and high concentration contribution source areas were from southern Ningxia, southeast Gansu and western Shaanxi. The airflow was mainly transported over long distances during the sandstorm event, and high concentration contribution source areas were from northwestern Inner Mongolia, southern Russia, northern and southwestern Mongolia, and northern Xinjiang. A health risk analysis showed that the risk to human health during sandstorm days related to the chemical composition of particles was generally 1.2–13.1 times higher than during non-sandstorm days. Children were more susceptible to health risks, about 2–6.3 times more vulnerable than adults to the risks from heavy metals in the particles under both weather conditions.

The uneven rainfall distribution, limited soil nutrients, and continuous cropping effect in the Loess Plateau restrict the sustainable development of fruit tree/crop (soybean and maize) intercropping systems. A two-year field experiment was conducted to investigate the effects of different water and fertilizer regimes on the soil nutrients and growth of intercropping systems during the crop replacement period. The experiment involved three irrigation levels (0% (I₀), 50% (I₁), and 80% (I₂) of field capacity), two irrigation methods (drip irrigation (DI) and flood irrigation (FI)), and three fertilizer application rates (0 (F₀), 375 (F₁), and 750 (F₂) kg/hm²). The results showed that in 2020 and 2021, the soil water contents increased with increasing irrigation and fertilization. The soil ammonium nitrogen, nitrate nitrogen, and soil organic matter contents in 2021 were 21.0%–68.4% higher than those in 2020. Increasing the fertilizer application rate improved the photosynthesis rate and transpiration rate of apples and maize in 2020 but had a reverse U-shape effect on soybeans in 2021. Irrigation and fertilization increased soybean and maize yields by 2.9%–30.5% compared with the I₀F₀ treatment. The maize root indicators generally showed an increasing trend followed by a decreasing trend with increasing fertilizer application in 2020, while soybean exhibited an opposite pattern in 2021. The FI₁F₁ and DI₂F₂ treatments yielded the optimal economic benefit in 2020 and 2021, respectively. Therefore, from an economic standpoint, FI and DI would have been recommended in 2020 and 2021, respectively. Factor analysis suggested that the DI₂F₂ treatments had the highest comprehensive benefits over the two years studied. Therefore, we recommend using DI combined with 80% field capacity irrigation and 750 kg/hm² fertilization to maximize the comprehensive benefits of intercropping systems during the crop replacement period.