关键词: 石化水库, 干旱地区, 土壤理化性质, 化学计量比, 生物量

Abstract:

A water reservoir had been constructed using a natural depression of the gobi desert—an arid region of Xinjiang, China—for a petrochemical enterprise. The industry discharged large quantities of treated wastewater into the reservoir, forming an artificial water body. This phenomenon created a unique wetland, remarkably altering soil-vegetation relationships within the surrounding desert ecosystem. This reclamation study employed soil profiling to investigate seven plant communities that typically border the reservoir and examine their influence on the soil’s physicochemical properties, including carbon-nitrogen-phosphorus stoichiometry and biomass. The results are summarized as follows: (1) Soil bulk density increased markedly with depth (1.28-1.72 g·cm^-3). Such an effect was most prominent within the 0-60 cm layer, induced by a Tamarix ramosissima-Phragmites australis symbiotic association, as these plants were under grazing pressure and had shallow root systems. Soil water content exhibited a “low in surface layers-high in deeper layers” distribution pattern. However, soils with slight alkalinity (pH 8.15-8.94) and low cation exchange capacity across the study area may induce base cation saturation, constraining water availability, a condition exacerbated by the limited abilities of the native vegetation to mitigate evaporation. Nutrient contents—total nitrogen, total phosphorus, and organic carbon—of the surface layer were enriched, as the T. ramosissima-P. australis symbiosis enhanced the nitrogen-fixing capacities of the individual species, facilitating soil nitrogen accumulation. (2) Stoichiometry revealed C:N, C:P, and N:P ratios of 6.45-9.07, 2.77-4.20, and 0.33-0.52, respectively, indicating a severely imbalanced state characterized by nitrogen limitation but relative phosphorus enrichment. (3) The T. ramosissima-P. australis association exhibited the highest biomass per unit area (39.67 t·hm^-2), which was significantly greater than that of the other associations (P<0.05). Redundancy analysis identified total nitrogen, soil water content, and bulk density as key driving factors, which explained 23.4%, 17.7%, and 21.4% of the variance, respectively. Thus, the wetlands created by the reservoir facilitated restoration of the native vegetation by improving soil-plant interactions. However, the salinity-induced imbalance in nitrogen-phosphorus stoichiometry and constrained water availability continued to limit ecological functioning. Thus, ecological restoration must prioritize the introduction of salt-tolerant and nitrogen-fixing species as well as optimization of soil water regulation strategies. These results serve as a scientific reference for rehabilitating other petrochemical industrial zones in Xinjiang by creating wetlands.

Key words: petrochemical reservoir, arid region, soil physicochemical properties, stoichiometric ratios, biomass