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Due to severe mass transfer limitations, contaminated soils with low-permeability limit the accessibility of amendments, resulting in less effective or even ineffective remediation. Enhancing the mass transfer properties of low-permeability soils by hydraulic fracturing is a promising technique. A quasi-three-dimensional (quasi-3D) analytical model was presented that accounted for advection-diffusion-adsorption-degradation processes in the fracture-matrix system. The model combined the injection-extraction technique to investigate the enhanced transport of amendments in low-permeability contaminated soil by hydraulic fractures. Then, the injection strategy and controllable parameter optimization were comprehensively studied by analyzing the radial transport behavior of the amendment within hydraulic fractures. The results showed that higher injection volumetric rates accelerated the formation of a uniform line source within the fractures. Although the differences in the effective ratio of the amendment among different injection modes were not significant, considering the amendment utilization rate and cost reduction, the recommended injection strategy was the combination of continuous pulsing injection and periodic injection.

Agropyron cristatum,a wild relative of common wheat (Triticum aestivumL.), provides many desirable genetic resources for wheat improvement, such as tolerance to cold, drought, and disease. To transfer and utilize these desirable genes, in this study, two wheat-A. cristatumderivatives II-13 and II-23 were identified and analyzed. We found that the number of root tip cell chromosomes was 44 in both II-13 and II-23, but there were four and six P genome chromosomes in II-13 and II-23, respectively, based on genomic in situhybridization (GISH). The chromosome configurations of II-13 and II-23 were both 2n=22II by the meiotic analysis of pollen mother cells (PMCs) at metaphase I, indicating that there were two and three pairs of P chromosomes in II-13 and II-23, respectively. Notably, wheat chromosome 7D was absent in derivative line II-13 while II-23 lacked chromosomes 4B and 7A based on SSR analysis combining fluorescence in situhybridization (FISH) analysis with pAs1 and pSc119.2 as probes. Chromosomes 2P and 7P were detected in both II-13 and II-23. Another pair of P genome chromosomes in II-23 was determined to be 4P based on expressed-sequences tags-sequence tagged sites (EST-STS) markers specific to A. cristatumand FISH with probes pAcTRT1 and pAcpCR2. Overall, these results suggest that II-13 was a 7P (7D) substitution line with one pair of additional 2P chromosomes and II-23 was a multiple 4P (4B), 7P (7A) substitution line with one pair of additional 2P chromosomes. Moreover, we obtained six alien disomic addition lines and five alien disomic substitution lines by backcrossing. These new materials will allow desirable genes from A. cristatumto be used in common wheat.