Evaluation of soil quality in iron tailing ore wastelands of various reclamation periods

ObjectiveThe effects of different reclamation periods on the soil quality of iron tailing ore wasteland were studied, which provided a basis for revealing the succession law and ecological management of reclaimed soil in iron tailing ore wasteland.

MethodThis paper treats the iron tailing ore wastelands with various reclamation periods (1, 3, 5, 7 and 15 years) in Malanzhuang Town, Qian’an of Tangshan, northern China as the objects of study, while the bare tailings as the control; meanwhile, the minimum dataset (MDS) for evaluating soil quality was constructed through the gray correlation degree model and correlation analysis, after taking the soil physiochemical and biological characters in 0−20 cm, 20−40 cm and 40−60 cm soil layers into comprehensive consideration. Moreover, the index membership was calculated by the membership function, while the index weight was determined using principal component analysis (PCA), and the quality of the reclaimed soils in iron tailings was finally evaluated using the weighted summation model.

ResultThe results suggested that the MDS applicable for soil quality evaluation should include 5 indexes, namely, fungus, phosphatase, urease, non-capillary porosity and total nitrogen, among which, phosphatase and urease factor loading amount displayed great gray correlation degrees, which were the key indexes for evaluating the reclaimed soil quality in that area. Besides, the MDS-based soil quality index (MDS-SQI) displayed extremely significant correlation with the total data set-based SQI (TDS-SQI) (R² = 0.911), the results calculated by the weighted summation model indicated that, the SQI of various reclamation years followed the order of reclamation for 15 years > 7 years > 5 years > 3 years > 1 year > bare tailings. In addition, the soil quality comprehensive value during reclamation for 1−15 years was increased in a regression parabola manner, among which, the soil quality was slowly improved within reclamation for 1−7 years, but it was rapidly recovered after reclamation for 7 years and peaked at 15 years of reclamation. Additionally, the vertical section variation trend of soil quality at various reclamation years was basically decreased with the increase in soil depth.

ConclusionSoil reclamation can improve the soil quality in iron tailing ore wasteland, which can provide reference for revealing the evolutionary changes and ecological management of reclaimed soils in iron tailing ore wastelands.