Faculty of Natural Resources & Marine Sciences, Tarbiat Modares University, 46417-76489 Noor, Mazandaran, Iran.
Department of Sciences and Forest Engineering, Sari Agricultural Sciences and Natural Resources University, Mazandaran, Iran.
Sci Total Environ. 2023 Oct 20;896:166341. doi: 10.1016/j.scitotenv.2023.166341. Epub 2023 Aug 18.
The storage of municipal solid wastes in unengineered landfills poses a severe threat to soil functions and health. Wastes seriously threaten human health and the terrestrial ecosystem, especially due to heavy metals. There is a general knowledge gap about the long-term impacts of storage wastes on the soil health indicators which are effective on soil functions. This investigation focuses on the examination of landfill leachate on soil health indicators from different years in the Hyrcanian forest region in northern Iran. For this purpose, soil sampling was done in the summer of 2012 and 2022 (from three depths of 0-10, 10-20, and 20-30 cm and on a surface of 30 cm × 30 cm). Soil samples were randomly collected from a polluted forest used as waste storage and a nearby unpolluted protected forest. In addition to the general soil physical, chemical and biological parameters, the amounts of cadmium (Cd) and lead (Pb) in the soil were also measured. Simultaneously with soil sampling, earthworms (from a depth of 0-30 cm) were collected and identified. Also, the concentration of Cd and Pb in the earthworm's biomass were measured in the laboratory. We found that unpolluted sites had maximum values of N, K, P, and Ca than the polluted sites. In addition, a decrease of soil aggregates stability, nutrient contents, microbial and enzyme activities, and also fauna and microflora abundance were found in the polluted sites in the period 2012-2022. Soil Cd and Pb contents were more in the polluted site in 2022 compared to the unpolluted site. Lumbricus rubellus and Lumbricus terrestris earthworms had significantly higher population in the polluted sites and higher accumulation of Cd and Pb in biomass. According to our results, soil health decreased in the order unpolluted site 2022 > unpolluted site 2012 > polluted site 2012 > polluted site 2022, which corresponds with the reduction of soil health during the release of landfill leachate. This investigation contributes to understand landfill pollution derived from leachate and its effects on soil physical, chemical and biological parameters to help managing landfill leachate. Therefore, the main issue is choosing a landfill system that minimizes the risk of pollution, installing a leachate collection system and constructing a landfill with engineering principles that can reduce the effects of urban waste pollution on soil health. We emphasize that landfilling is dangerous for the environment, so the government should implement sanitary landfilling to prevent further contamination of surface and underground waters, as well as soil in the precious Hyrcanian forest.
未经工程设计的垃圾填埋场储存城市固体废物对土壤功能和健康构成严重威胁。废物严重威胁人类健康和陆地生态系统，尤其是重金属。人们对储存废物对土壤健康指标的长期影响知之甚少，而这些指标对土壤功能有效。本研究重点考察了伊朗北部赫卡尼亚森林地区不同年份垃圾渗滤液对土壤健康指标的影响。为此，于 2012 年和 2022 年夏季（从 0-10、10-20 和 20-30 厘米三个深度以及 30 厘米×30 厘米的表面）进行了土壤采样。土壤样品是从用作废物储存的污染森林和附近未受污染的受保护森林中随机采集的。除了一般的土壤物理、化学和生物参数外，还测量了土壤中的镉（Cd）和铅（Pb）含量。同时进行了土壤采样，从 0-30 厘米深采集并鉴定了蚯蚓。此外，还在实验室测量了蚯蚓生物量中的 Cd 和 Pb 浓度。我们发现，未受污染的地点的 N、K、P 和 Ca 含量高于污染的地点。此外，在 2012 年至 2022 年期间，污染地点的土壤团聚体稳定性、养分含量、微生物和酶活性以及动物区系和微生物区系丰度均有所下降。2022 年污染点的土壤 Cd 和 Pb 含量高于未污染点。在污染点，Lumbricus rubellus 和 Lumbricus terrestris 蚯蚓的种群数量明显较高，生物量中 Cd 和 Pb 的积累量也较高。根据我们的结果，土壤健康状况的顺序为未污染点 2022>未污染点 2012>污染点 2012>污染点 2022，这与垃圾渗滤液释放过程中土壤健康状况的降低相对应。本研究有助于了解垃圾渗滤液引起的垃圾填埋场污染及其对土壤物理、化学和生物参数的影响，以帮助管理垃圾渗滤液。因此，主要问题是选择一种能将污染风险降到最低的垃圾填埋系统，安装一个渗滤液收集系统，并按照工程原理建造一个垃圾填埋场，以减少城市废物污染对土壤健康的影响。我们强调，土地填埋对环境是危险的，因此政府应实施卫生土地填埋，以防止表面和地下水资源以及珍贵的赫卡尼亚森林土壤的进一步污染。
