Cover layers to the growth of trees and shrobs over a sulfide spoil from gold mining

Abstract

-This work was done at a gold mine company in Paracatu, MG, Brazil, and was conducted from March 2000 to November 2005. The substrate (spoil) studied was a phillite rock which contains sulfides such as pyrite and arsenopyrite. This study aimed to evaluate the survival and growth of plant species on different combinations of substrate layers over the spoil. These layers were a cover layer and a sealing layer, both deposited over the spoil. The treatment 1 had saprolite (B1) in the sealing layer (SL) and B1 with liming (B1L) in the cover layer (CL). The treatment 2 had B1 in SL and B1L + soil with liming (SoL) in the CL. The treatment 3 had B1 + SoL in the SL and B1L in the CL. The treatment 4 had B1 + SoL in the SL and B1L + SoL in the CL. The plant species used were Acacia farnesiana, A. holosericea, A. polyphylla, Albizia lebbeck, Clitoria fairchildiana, Flemingia sp., Mimosa artemisiana, M. bimucronata e Enterolobium contortisiliquum. Forty and 57 months after planting, collardiameter, height, and living plants were evaluated. The greatest survival rate was oobservedintreatmentwith B horizon of an Oxisoil in both layers, with 80 %. In general, M. bimucronata and A. farnesiana species showed the highest survival rate. The arsenic-content by Mehlich 3 in the cover layer ranged from 0.00 to 14.69 mg dm -3 among treatments. The experimental results suggest that layers combinations above the sulfide substrate allow the rapid revegetation of the spoil.Keywords: Sulfide substrate, Reforestation and Land reclamation. CAMADAS DE COBERTURA PARA O CRESCIMENTO DE ÁRVORES E ARBUSTOS SOBRE UM SUBSTRATO SULFETADO DE MINERAÇÃO DE OURO RESUMO -Este trabalho foi desenvolvido em área de mineração de ouro no

Tropical surface gold mining: A review of ecological impacts and restoration strategies

“…In general, leguminous trees have relatively high survival rates, even in the least fertile substrates of former gold mine sites, though there is variability based on site conditions and species (Baez et al, 2022; Haimbili et al, 2016; Mulligan et al, 2006; Tetteh, Ampofo, & Logah, 2015). For example, after one year, planted Acacia seedlings had a survival rate of about 45% in unamended tailings in one field experiment (Haimbili et al, 2016), whereas up to 100% of Acacia and Mimosa seedlings still survived five years after being planted on fertilized and limed overburden in another study (Assis et al, 2011) (see Annex D for summaries of field‐based planting experiments). Plantings of legumes can improve mine substrates by fixing nitrogen into the soil, and may also serve as a sustained source of organic matter by providing leaf litter (Peláez et al, 2013; Schimann et al, 2012; Thomas, 2014).…”

“…Woody species may not readily establish on the steeply sloped, particularly infertile growing substrate of tailings dams and overburden heaps. Initial fertilization (Mulligan et al, 2006; Nsiah & Schaaf, 2020; Weiersbye et al, 2006), irrigation, and transplantation of nursery‐hardened containerized (rather than bare‐root) seedlings (Mulligan et al, 2006; Weiersbye et al, 2006), liming (Assis et al, 2011), and the incorporation of B‐horizon subsoils into the growing substrate (Assis et al, 2011; Nsiah & Schaaf, 2020) can all improve the survival of planted trees. However, many introduced woody species cannot survive long‐term in these environments without continued amelioration, and in particularly unsteady surfaces, perennial herbs and shrubs may be more effective than trees at stabilizing these systems (Assis et al, 2011; Rossouw et al, 2009) (see Annex B: Treatments for Tailings Dams).…”

Influência de diferentes tipos de solos da Caatinga na germinação de espécies nativas

“…Espécies nativas de ambientes semiáridos apresentam tendência a elevadas germinações em curtos períodos de tempo, tendo índices favoráveis na velocidade de germinação e tempo médio de geminação. Este fato é condizente com as condições climáticas da região, onde devido à escassez e irregularidade de chuvas, a água fica disponível no solo durante um curto período de tempo e as espécies precisam usar de suas estratégias para completar o mais rápido possível seu processo germinativo e se estabelecer (MEIADO et al, 2012 (ASSIS et al, 2011;LIMA et al, 2015;GONÇALVES, 2017). Essa espécie ocorre em diferentes biomas brasileiros e em países da América, sendo conhecida pela elevada rusticidade e considerada daninha quando ocorre em pastagens, devido seu alto vigor, tendo assim bom desempenho em diferentes condições ambientais (LORENZI, 2002).…”