RESUMEN
The landscape pattern determines water pollution source and sink processes and plays an important role in regulating river water quality. Due to scale effects, studies on the relationship between landscape pattern and river water quality showed variance at different scales. However, there is still a lack of integrated study on the scale effect of landscape pattern and river water quality dynamics. This study collected 4 041 data from results of previous publications to address the characteristics of landscape pattern and river water quality dynamics at different scales and to identify the key temporal and spatial scales as well as landscape pattern indices for regulating river water quality. The results indicated that, compared to precipitation events, base flow periods, and interannual scales, the high-flow period was the key temporal scale for linking landscape pattern on river water quality. Compared to the watershed scale, the landscape pattern of buffer zones had a greater impact on river water quality. The high-flow period-buffer zone scale was the key spatiotemporal coupling scale for linking landscape pattern and river water quality. Compared to croplands, water bodies, grasslands, and the overall landscape of the watershed, the landscape pattern of forests and urban areas had a greater impact on river water quality. Fragmentation degree was the most important landscape pattern factor regulating river water quality. In river water quality management, it is important to focus on the landscape configuration of buffer zones, increase forest area, reduce patch density of forests and water bodies, and decrease the aggregation degree of urban areas.
RESUMEN
Bioleaching is a promising route for electrolytic manganese (Mn) residue (EMR) reutilization due to being eco-friendly and cost-effective. However, microbes with high bioleaching efficiency are scarce. This work aimed to isolate, screen, and characterize a novel fungal strain with high Mn-bioleaching efficiency from EMR, and study the kinetics and mechanism. The novel Penicillium oxalicum strain Z6-5-1 was found to selectively bioleach Mn from EMR. A maximum Mn2+ recovery of 93.3 % was achieved after 7 days and was mainly dependent upon acidolysis of the bio-organic acids, specifically gluconic acid and oxalic acid, as well as mycelial biosorption. This efficiency was the highest reported in the literature for a fungus over such a short time. EMR strongly induced P. oxalicum to produce gluconic acid and oxalic acid. The novel transcription factor PoxCxrE of P. oxalicum controlled the production of bio-organic acids by regulating the expression of rate-limiting enzyme genes involved in the biosynthesis of bio-organic acids. Scanning electron microscopy, laser particle size analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were employed to analyze EMR changes after bioleaching. This study provides an alternative fungal resource for Mn-bioleaching of EMR, and a novel target for metabiotic engineering to improve bio-organic acid production.
