IRNAS, CSIC, Avenida Reina Mercedes 10, 41012, Seville, Spain.
Environmental and Water Agency. Regional Government of Andalusia, (Agencia de Medio Ambiente y Agua de Andalucía, AMAyA), Johan G. Gutenberg 1, 41092, Seville, Spain.
J Environ Manage. 2021 Feb 15;280:111848. doi: 10.1016/j.jenvman.2020.111848. Epub 2020 Dec 23.
The restoration of mining areas, in particular if they are located near towns or villages, is essential to reduce their potential risks for human health and to minimize their visual impacts. In this study, we assess the rehabilitation of a waste rock pile adjacent to the town of Tharsis (SW Spain). We measured vegetation cover and its diversity, and chemical composition of plants and soil, twelve years after remediation by lime amendments, added topsoil and planted vegetation. In general, the applied measures were successful covering with woody vegetation the upper part of the waste rock pile, and providing a greening visual landscape for the town nearby. The most abundant species were the gum rockrose (Cistus ladanifer) and the legume shrub Retama sphaerocarpa, this latter species most probably introduced in the seedbank of the added topsoil. Also in the soil seedbank, probably arrived the invasive Acacia saligna, of fast growth. In contrast, the lower part of the slopes was almost devoid of vegetation. We interpret that partial failure in the rehabilitation process as due to the acid mine drainage, which caused downslope a decrease of soil pH and increased availability of trace elements, thus impeding growth and establishment of plants. In addition, some plants, like C. ladanifer, growing at the base of the rock pile, had concentrations of Cd above the maximum tolerable level for animals, therefore representing a toxicity risk. Finally, we propose here an alternative technique to restore waste rock piles, by sorting and selectively handling the extractive wastes, thus reducing infiltration rates, seepages and the negative effect of the acid mine drainage. Those modified waste rock piles will be rehabilitated by the addition of topsoil and planted vegetation, as successfully worked out in the upper slopes of the study site.
矿区的恢复，特别是如果它们位于城镇或村庄附近，对于降低其对人类健康的潜在风险和最小化其视觉影响至关重要。在本研究中，我们评估了西班牙西南部塔西斯镇附近废石堆的修复情况。我们测量了植被覆盖度及其多样性，以及植物和土壤的化学组成，这是在添加石灰改良剂、表土和种植植被后 12 年进行的。总的来说，所采取的措施非常成功，用木本植被覆盖了废石堆的上部，为附近的城镇提供了绿化的视觉景观。最丰富的物种是乳香岩蔷薇（Cistus ladanifer）和豆科灌木金雀儿（Retama sphaerocarpa），后一种物种很可能是添加表土的种子库中引入的。同样，在土壤种子库中，可能还存在生长迅速的入侵物种银荆（Acacia saligna）。相比之下，山坡的下部几乎没有植被。我们认为修复过程的部分失败是由于酸性矿山排水造成的，这导致坡下土壤 pH 值降低，痕量元素的可用性增加，从而阻碍了植物的生长和定植。此外，一些植物，如生长在废石堆底部的乳香岩蔷薇，其 Cd 浓度超过了动物的最大耐受水平，因此存在毒性风险。最后，我们在这里提出了一种修复废石堆的替代技术，通过对采掘废物进行分类和有选择地处理，从而降低渗透速率、渗流和酸性矿山排水的负面影响。那些经过改良的废石堆将通过添加表土和种植植被来修复，就像研究地点的上部斜坡所成功实施的那样。
