Salinity may increase metal mobilization with a potentially significant consequence for soil enzymatic activity and nutrient cycling. The goal of this study was to investigate changes in soil enzyme activity in response to salinization of a clay loam soil artificially polluted with cadmium (Cd) and lead (Pb) during a 120-day incubation experiment. Soil samples were polluted with Cd (10 mg Cd kg⁻¹), Pb (150 mg Pb kg⁻¹), and a combination of Cd and Pb, then preincubated for aging and eventually salinized with three levels of NaCl solution (control, low and high). NaCl salinity consistently increased the mobilization of Cd (12–22%) and Pb (5–16%) with greater increases at high (17–22% for Cd, 9–16% for Pb) than low (12% for Cd, 5–7% for Pb) salinity levels. While the increased Cd mobilization was greater in co-polluted (22%) than Cd-polluted (17%) soils, the increase of Pb mobilization was lower in co-polluted (9%) than Pb-polluted (16%) soils at high salinity level. The salinity-induced increases in metal mobilization significantly depressed soil microbial respiration (up to 43%), microbial biomass content (up to 63%), and enzymatic activities (up to 87%). The multivariate analysis further supported that the increased soil electrical conductivity, Cd mobilization, and pH after salinization were the most important factors governing microbial activity and biomass in metal-polluted soils. Results showed that changes in microbial biomass and mobile metal pool with increasing salinity had a major effect on enzyme activities, particularly under the combined metals. This study indicated that the secondary salinization of metal-polluted soils would impose an additional stress on enzymatic activities as biochemical indicators of soil quality, and therefore should be avoided for the maintenance of soil microbial and biochemical functions, especially in arid regions. In metal-polluted soils, the observed responses of extracellular and intracellular enzymes to salinity can be used to advance our knowledge of microbial processes when modeling the carbon and nutrient cycling.

盐度可能会增加金属动员，对土壤酶活性和养分循环有潜在的重大影响。本研究的目的是在为期 120 天的孵化实验中，研究人工污染了镉 (Cd) 和铅 (Pb) 的粘壤土的盐渍化后土壤酶活性的变化。土壤样品被 Cd (10 mg Cd kg ^-1 )、Pb (150 mg Pb kg ^-1)，以及 Cd 和 Pb 的组合，然后预培养老化并最终用三个水平的 NaCl 溶液（对照、低和高）盐化。NaCl 盐度始终增加 Cd (12-22%) 和 Pb (5-16%) 的迁移，高浓度（Cd 17-22%，Pb 9-16%）比低浓度（Cd 12%， Pb) 盐度水平为 5–7%。虽然共同污染 (22%) 土壤中 Cd 动员的增加大于 Cd 污染 (17%) 土壤，但共同污染 (9%) 中 Pb 动员的增加低于 Pb 污染 (16%) 土壤盐度高。盐度引起的金属动员增加显着抑制了土壤微生物呼吸（高达 43%）、微生物生物量含量（高达 63%）和酶活性（高达 87%）。多变量分析进一步支持土壤电导率增加，Cd 动员和盐渍化后的 pH 值是控制金属污染土壤中微生物活动和生物量的最重要因素。结果表明，随着盐度的增加，微生物生物量和移动金属池的变化对酶活性有重大影响，特别是在结合金属的情况下。该研究表明，金属污染土壤的次生盐渍化会对作为土壤质量生化指标的酶活性施加额外的压力，因此应避免进行土壤微生物和生化功能的维持，尤其是在干旱地区。在金属污染的土壤中，观察到的细胞外和细胞内酶对盐度的反应可用于在模拟碳和养分循环时提高我们对微生物过程的了解。盐渍化后的 pH 值和 pH 值是控制金属污染土壤中微生物活动和生物量的最重要因素。结果表明，随着盐度的增加，微生物生物量和移动金属池的变化对酶活性有重大影响，特别是在结合金属的情况下。该研究表明，金属污染土壤的次生盐渍化会对作为土壤质量生化指标的酶活性施加额外的压力，因此应避免进行土壤微生物和生化功能的维持，尤其是在干旱地区。在金属污染的土壤中，观察到的细胞外和细胞内酶对盐度的反应可用于在模拟碳和养分循环时提高我们对微生物过程的了解。盐渍化后的 pH 值和 pH 值是控制金属污染土壤中微生物活动和生物量的最重要因素。结果表明，随着盐度的增加，微生物生物量和移动金属池的变化对酶活性有重大影响，特别是在结合金属的情况下。该研究表明，金属污染土壤的次生盐渍化会对作为土壤质量生化指标的酶活性施加额外的压力，因此应避免进行土壤微生物和生化功能的维持，尤其是在干旱地区。在金属污染的土壤中，观察到的细胞外和细胞内酶对盐度的反应可用于在模拟碳和养分循环时提高我们对微生物过程的了解。