Chemico‐mineralogical changes of ultramafic topsoil during stockpiling: implications for post‐mining restoration

Abstract

Lateritic topsoils, which are usually removed and stored apart before mining operations take place, play an essential role in the success of post‐mining restoration. They contain elements to recover chemical (organic matter, nutrients) and biological (seed and bud banks, microorganisms) fertility of the soil. Conserving topsoil fertility during storage time is essential for a successful use of topsoil during restoration. In this study, different chemico‐mineralogical properties of a lateritic topsoil from the Goro nickel mine (New Caledonia) were monitored from its original in situ emplacement on the soil profile, immediately after its stockpiling and after 24 months of storage. Our analyses show that topsoil experienced noticeable changes immediately after storage, mostly produced by mixing of different soil profiles. Cation Exchange Capacities and concentrations of most elements did not vary even after 24 months of storage. However, a slight reduction of Ni, Cr, K, Na and of the C:N ratio, and an increase of Ca have been observed. Stockpiling has not affected negatively the chemical fertility of the topsoil, although biological parameters should be considered to have a complete view of stockpiling sustainability.

A global forum on ultramafic ecosystems: from ultramafic ecology to rehabilitation of degraded environments

“…Over the years, the issue of how to restore or rehabilitate ultramafic environments that have been affected by mining, quarrying or other activities, has gained substantial attention at the ICSEs. Three articles published in the Special Issue report on different case studies related to this topic (Boisson et al 2018;Mizuno et al 2018;Quintela Sabarı´s et al 2018).…”

“…Quintela Sabarı´s et al (2018) report how the properties of a topsoil in a nickel-laterite opencast mining operation evolve during stripping and storage and what consequences can be expected when re-using this material in post-mining rehabilitation. The following two papers report experiences and case-studies of how the use of metallophytes can be successful for the rehabilitation of mine and quarry sites.…”

Study on the Effect of Topsoil Storage Mode on Topsoil Availability

“…With the increase of the burial depth, the losses of soil pH, total nitrogen, total phosphorus, total potassium, and organic matter are diminished. This may be because the microbial activity in the topsoil is higher than that in the soil inside the heap (Visser et al, 1984), which leads to the rapid nutrient transformation in the surface soil of the heap; and it may also be due to a small amount of rainfall in the study area in spring leading to decomposition of organic matter in topsoil and leaching of some nutrients from the soil (Quintela et al, 2018). Some studies have shown that the soil organic matter inside the heap increases after a long-term stacking of topsoil (Williamson and Johnson, 1990).…”

Effects of reclamation effort on the recovery of ecosystem functions of a tropical degraded serpentinite dump site

“…Topsoil can be used as an inoculum to provide seedbanks and microbiota to ensure the colonisation of disturbed soil (Bradshaw, 2000(Bradshaw, , 1997. However, this approach requires careful handling of topsoil, as well as stockpiling under appropriate conditions, and fast reapplication of topsoil to ensure biological activity (Echevarria and Morel, 2015;Quintela-Sabarís et al, 2018). The use of organic wastes and industrial by-products may also be considered as an amendment for soil construction (Echevarria and Morel, 2015;O'Dell and Claassen, 2009;Séré et al, 2008).…”