Acidification can alter soil ecosystem functioning, thus jeopardizing the provision of valuable ecosystem services. Moreover, soil acidification can be accompanied by other soil threats, such as, for instance, metal pollution. The aim of this work was to assess to what extent acidification affects the functionality of metal polluted soils. To this aim, the pH of two soils (a highly metal polluted and a moderately metal polluted soil) was lowered by adding elemental sulphur at different doses, resulting in the following pH gradient in both soils: 7.5, 7.0, 6.5, 6.0, 5.5, 5.0, 4.5, 4.0 and 3.5. A variety of microbial indicators of soil health were measured in the treated soils: enzyme activities, substrate-induced respiration, microbial biomass carbon, bacterial and fungal abundances by qPCR, and bacterial and fungal richness by DGGE. Metal (Cd, Cu, Pb, Zn) bioavailability increased at decreasing pH values. The values of enzyme activities were strongly affected by acidification in both soils, followed by the values of soluble organic carbon in the highly polluted soil and bioavailable metal concentrations in the moderately polluted soil. These results improve our understanding of the role of microorganisms in the biogeochemical cycles of metal polluted acidic soils.

酸化会改变土壤生态系统的功能，从而危及提供宝贵的生态系统服务。此外，土壤酸化还可能伴随着其他土壤威胁，例如金属污染。这项工作的目的是评估酸化在多大程度上影响金属污染土壤的功能。为此，通过添加不同剂量的元素硫降低了两种土壤（高金属污染和中金属污染的土壤）的pH，导致两种土壤的pH梯度分别为：7.5、7.0、6.5、6.0、5.5 ，5.0、4.5、4.0和3.5。在处理过的土壤中测量了多种土壤健康的微生物指标：酶活性，底物诱导的呼吸作用，微生物生物量碳，qPCR检测细菌和真菌的丰度，以及DGGE检测细菌和真菌的丰富度。金属（镉，铜，pH值降低时，Pb，Zn）的生物利用度增加。两种土壤中的酸化都强烈影响酶活性的值，其次是高污染土壤中的可溶性有机碳和中度污染土壤中的生物有效性金属浓度。这些结果增进了我们对微生物在金属污染的酸性土壤的生物地球化学循环中作用的认识。