ABSTRACT

In this study, Pb was added to the soil at rates of 0, 100, 200, 300, 400, and 500 mg kg⁻¹ as Pb (NO₃)₂ and then incubated at 27 °C and soil moisture of 0.7 field capacity for 180 d. Soil biological characteristics including acid and alkaline phosphomonoesterases (ACP and ALP), nitrate reductase (NR), and urease (UA) activities, microbial biomass carbon (MBC), and basal respiration (BR) were measured at time points of 3, 15, 30, 90, and 180 d. NR was increased at 3 and 15 d of incubation at Pb levels of 100 and 200 mg kg⁻¹. After 30 d of incubation, an increment of ALP was observed from 0 to 200 mg kg⁻¹, while the other indices decreased by increasing Pb levels for all time points. By increasing the incubation time, we found a remarkable decrease in microbial indices even in low levels of Pb. Considering all determined biological indices, the results revealed that at time points longer than 30 d in which the added Pb levels reached the equilibrium in this soil, the Pb levels of 200–300 mg kg⁻¹ can be considered as the critical range of Pb concentration in the tested soil.

摘要

在本研究中，以 Pb (NO ₃ ) ₂的形式将 Pb 以 0、100、200、300、400和 500 mg kg ^-1的比例添加到土壤中，然后在 27 °C 和 0.7 田间持水量的土壤湿度下培养180 天。在 3, 15, 30、90 和 180 天。^{NR 在 100 和 200 mg kg -1}的 Pb 水平下孵育 3 天和 15 天时增加。孵育 30 d 后，观察到 ALP 从 0 增加到 200 mg kg ^-1, 而其他指数随着所有时间点的 Pb 水平的增加而下降。通过增加孵育时间，我们发现即使在低铅水平下微生物指数也显着下降。综合所有确定的生物指标，结果表明，在该土壤中添加的铅水平达到平衡的时间点超过 30 d 时，200-300 mg kg ^-1的铅水平可以被认为是铅的临界范围。被测土壤中的浓度。