Abstract Climate change and population growth generates a decrease in water availability around the world which can compromise the maintenance of sustainable agriculture. Thus, treated wastewater (TWW) became an alternative to minimize water shortage. However, this may indirectly affect the soil’s microbial properties. In this study different soils irrigated for 0, 1, 8 and 20 years with TWW were sampled and from the east central region of Tunisia. The objective was to investigate its effect on heavy metal accumulation and enzyme activities of β-glucosidase, arylsulfatase, acid phosphatase, alkaline phosphatase, urease, dehydrogenase and fluorescein diacetate (FDA). Moreover, carbon microbial biomass (Cmic) using Substrate induced respiration (SIR) technique and microbial functional diversity using Biolog EcoPlate™ were assessed. Our results had shown a crucial decrease of the enzymatic activities in soils that were newly irrigated with TWW, while a crucial increase was recorded in soils exposed to TWW for 20 years. In addition, chemical analysis revealed an important accumulation of heavy metals such as Cd, Cu, Zn and Ni along with the irrigation period, especially in 20 years-irrigated soils with TWW. The assessment of the bacterial functional diversity showed an important change in Average well color development (AWCD) and in diversity index values. Besides, substrate utilization profile revealed a significant variation along with the irrigation periods. In conclusion, long-term TWW irrigation has increased the metabolic activities of the soil’s microorganisms. Meanwhile, traces elements accumulation could pose a serious threat for biological processes in soils and a limiting factor for the reuse of TWW in agriculture.

中文翻译：

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突尼斯中东部地区（莫纳斯提尔省）长期处理污水灌溉下土壤酶活性和细菌功能多样性的重金属积累和变化

摘要 气候变化和人口增长导致全球水资源供应减少，这可能会影响可持续农业的维持。因此，处理过的废水 (TWW) 成为减少水资源短缺的替代方法。然而，这可能会间接影响土壤的微生物特性。在这项研究中，从突尼斯的中东部地区对用 TWW 灌溉了 0、1、8 和 20 年的不同土壤进行了采样。目的是研究其对 β-葡萄糖苷酶、芳基硫酸酯酶、酸性磷酸酶、碱性磷酸酶、脲酶、脱氢酶和荧光素二乙酸酯 (FDA) 的重金属积累和酶活性的影响。此外，还评估了使用底物诱导呼吸 (SIR) 技术的碳微生物生物量 (Cmic) 和使用 Biolog EcoPlate™ 的微生物功能多样性。我们的研究结果表明，新近用 TWW 灌溉的土壤中酶活性显着降低，而在暴露于 TWW 20 年的土壤中，酶活性显着增加。此外，化学分析表明，随着灌溉时间的推移，Cd、Cu、Zn 和 Ni 等重金属有重要的积累，特别是在 20 年的 TWW 灌溉土壤中。细菌功能多样性的评估显示平均孔颜色发展 (AWCD) 和多样性指数值发生了重要变化。此外，基质利用曲线显示出随着灌溉时间的显着变化。总之，长期TWW灌溉增加了土壤微生物的代谢活动。同时，