scholarly journals Changes of Technosol properties and vegetation structure along a chronosequence of dredged sediment deposition in areas with alluvial gold mining in Colombia

2020 ◽  
Vol 20 (5) ◽  
pp. 2377-2394 ◽  
Author(s):  
Bibiana Betancur-Corredor ◽  
Juan Carlos Loaiza-Usuga ◽  
Manfred Denich ◽  
Christian Borgemeister
Keyword(s):  
Vegetation Structure ◽  
Gold Mining ◽  
Sediment Deposition ◽  
Dredged Sediment ◽  
Alluvial Gold

scholarly journals Forest restoration after alluvial gold mining can recover vegetation structure. A case study in Colombia

2021 ◽  
Vol 23 (1) ◽  
pp. e969
Author(s):  
Sergio Esteban Lozano-Baez ◽  
José Ignacio Barrera-Cataño ◽  
Ricardo Ribeiro Rodrigues ◽  
Yamileth Domínguez-Haydar ◽  
Paula Meli
Keyword(s):  
Species Richness ◽  
Vegetation Structure ◽  
Forest Restoration ◽  
Gold Mining ◽  
Acacia Mangium ◽  
Vegetation Height ◽  
Spontaneous Succession ◽  
Passive Restoration ◽  
Alluvial Gold ◽  
Schizolobium Parahyba

Technical reclamation and spontaneous succession (passive restoration) are the two main approaches for restoring post-mining sites worldwide. Despite substantial differences between both approaches, little is known regarding how they differ in terms of ecological outcomes. We assessed and compared the vegetation structure and composition in one spontaneous succession forest that is 29 years old, two technically reclaimed forests that are 2 and 10 years old after alluvial gold mining, and one old-growth reference forest in northeastern Antioquia, Colombia. We sampled trees and saplings establishing three Modified-Whittaker Plots in each site. We measured tree basal area, canopy cover, vegetation height, tree density, and species richness. Vegetation structure and composition differed considerably among restoration approaches. Species richness was significantly greater in the spontaneous succession forest than at the other sites. Similarly, technical reclamation significantly increased the vegetation attributes after 10 years, reaching values similar to the reference forest. We underscore the importance of fast-growth planted species (Acacia mangium, Samanea saman, and Schizolobium parahyba) to revegetate mining degraded lands.

Mercury in soils impacted by alluvial gold mining in the Peruvian Amazon

2021 ◽  
Vol 288 ◽  
pp. 112364
Author(s):  
Manuel Gabriel Velásquez Ramírez ◽  
Claudia Maribel Vega Ruiz ◽  
Ronald Corvera Gomringer ◽  
Martin Pillaca ◽  
Evert Thomas ◽  
...  
Keyword(s):  
Gold Mining ◽  
Peruvian Amazon ◽  
Alluvial Gold

scholarly journals Anthropogenic Vegetation in the River Valley Amalat

2019 ◽  
Vol 16 ◽  
pp. 00049
Author(s):  
Marina Tsyrenova ◽  
Evgenia Pyzhikova ◽  
Elena Vasilyeva
Keyword(s):  
Vegetation Cover ◽  
Gold Mining ◽  
Research Study ◽  
Gold Deposits ◽  
Open Pit ◽  
Current State ◽  
Disturbed Areas ◽  
Alluvial Gold ◽  
Anthropogenic Vegetation ◽  
Mining Methods

The article presents the results of a research study of anthropogenic affects of gold mining on forest landscapes in Northern Transbaikalia, Russia and processes of natural reclamation of vegetation cover of the disturbed areas. The study area is located northwest of the Maliy Amalat River, which flows along the Vitim Plateau; in the floodplains of its two tributaries the Aunik River and the Bagdarin River. It is an area where a large number of alluvial gold deposits have been discovered. Some of these deposits are currently being developed, some have already been explored, and some have been abandoned. The authors consider the current state of vegetation cover in a key area of the Amalat River basin, near villages of Malovsky and Bagdarin. The problem of natural resources development and conservation is becoming extremely important for the area under study because open-pit gold mining methods that are used here drastically change the environment and affect water, land and forest resources.

scholarly journals Deforestación en el sureste de la amazonia del Perú entre los años 1999 - 2013; caso Regional de Madre de Dios (Puerto Maldonado – Inambari).

2016 ◽  
Vol 18 (3) ◽  
Author(s):  
Gabriel Alarcón ◽  
Jorge Díaz ◽  
Mauro Vela ◽  
Mishari García ◽  
José Gutiérrez
Keyword(s):  
Random Forest ◽  
Gold Mining ◽  
Rate Of Change ◽  
Landsat Images ◽  
Change Rate ◽  
Madre De Dios ◽  
Alluvial Gold ◽  
Annual Change Rate ◽  
The City

<p class="Default">El estudio cuantifica las áreas deforestadas en una de las zonas más impactadas por el hombre, al suroeste de la ciudad de Puerto Maldonado (Puerto Maldonado – Inambari), las imágenes Landsat TM 5 y 8 OLI fueron procesados utilizando una clasificación semiautomática denominada “Random Forest” propuesto por la <a href="http://reddcommunity.org/link/mesa-de-servicios-ambientales-y-redd-de-madre-de-dios">Mesa de Servicios Ambientales y Reducción de Emisiones de Gases de Efecto Invernadero Causadas por la Deforestación y Degradación de los Bosques de la Región Madre de Dios</a>, Perú. La metodología incluyo procedimientos de documentación, verificación y validación que permitieron evaluar la calidad de la información generada y los datos reportados. Los resultados de la investigación reportan; una superficie deforestada para los años 1999-2013 de 55426 ha, que representa una tasa anual de cambio de cobertura de – 0,22% y una deforestación anual promedio de 3 246 ha/año. De ello se deducen para los años 1999-2008, 2008-2011 y 2011-2013 tasas anuales de cambio de – 0,18%, -0,30% y -0,31%, con una deforestación anual promedio de 2 594 ha/año, 4 427 ha/año y 4 410 ha/año respectivamente. Los cambios producidos en el área de estudio, muestran la sistemática conversión de bosque a deforestación para el año 2008-2011 con 29 478 ha, siendo la mayor responsable el avance de la minería aurífera aluvial influenciada por la pavimentación de la vía interoceánica y por el alza del precio del oro como el agente principal de la deforestación, y en menor orden, la ampliación de la frontera agrícola, la ganadería y la actividad forestal.</p><p align="center"> </p><p align="center"><strong>ABSTRACT</strong></p><p>The study quantifies the deforested areas in one of the areas most affected by  humans, southwest in the city of Puerto Maldonado (Puerto Maldonado - Inambari), the Landsat images TM 5 and 8 OLI were processed using a semiautomatic classification called "Random Forest" proposed by Mesa de Servicios Ambientales y Reducción de Emisiones de Gases de Efecto Invernadero Causadas por la Deforestación y Degradación de los Bosques in the region of Madre de Dios, Peru. The methodology included documentation procedures, verification and validation to assess the quality of information generated and the data reported. The results of the investigation report; a deforested for years 1999-2013 of 55426 ha, which represents an annual rate of change of coverage of -0,22% and an average annual deforestation of 3246 ha/year. It deducted for the years 1999-2008, 2008-2011 and 2011-2013 annual rates of change of -0,18%, -0,30% and -0,31%, with an average annual deforestation of 2594 ha/year, 4427 ha/year and 4,410 ha/year respectively. Changes in the study area, show the systematic conversion of forest to deforestation for the year 2008-2011 with 29 478 ha, being most responsible advancing of alluvial gold mining influenced by the paving of the interoceanic highway and the gold price rises as the main agent of deforestation, and lower order, expanding the agricultural frontier, cattle rising and forestry.</p><p><strong><em>Key words: </em></strong>Cover change, Annual change rate, Random Forest, alluvial Gold Mining.</p><p> </p><p> </p><p><strong> </strong></p><p><strong> </strong></p><p><strong> </strong></p>

EARLY THEORIES AND PRACTICALITIES ON GOLD OCCURRENCE IN AUSTRALIA

2021 ◽  
Vol 40 (2) ◽  
pp. 409-432
Author(s):  
KENNETH G. McQUEEN
Keyword(s):  
Government Regulation ◽  
Gold Mining ◽  
Mining Industry ◽  
Great Depth ◽  
Gold Rush ◽  
Gold Deposits ◽  
Rock Types ◽  
Gold Occurrence ◽  
Alluvial Gold ◽  
Gold Bearing

The discovery of gold in Australia forced many changes to theory on the occurrence and origin of gold deposits. Initial discoveries appeared to confirm existing ideas on the global distribution of gold-bearing terrains. Later discoveries and research would show that this confirmation was largely coincidental, but nevertheless helpful in early prospecting. Prior to the first Australian gold rush, theoretical predictions of payable gold were made by Sir Roderick Murchison and Rev. W. B. Clarke based on knowledge of accidental gold finds and geological analogy with known areas of significant gold occurrence, particularly the Ural region in Russia. These predictions were overwhelmed when Edward Hargraves, realised he might be able to spark a gold rush that would prove the existence of payable gold. Hargraves travelled to the Bathurst region of New South Wales where numerous gold finds had already been made and with local guides, prospected Lewis Ponds Creek and the Macquarie River. He demonstrated the methods of alluvial mining, to John Lister and William and James Tom enabling them to find sufficient alluvial gold to initiate a gold rush. The crowd of attracted diggers demonstrated the existence of a payable goldfield. The unstoppable first rush resulted in the pragmatic introduction of government regulation and administration to allow alluvial gold mining. Other discoveries of payable goldfields quickly followed. As the local scientific expert on gold, W. B. Clarke was commissioned to conduct two extensive surveys of the goldfields between 1851 and 1853. Clarke also drew on his geological knowledge to provide practical advice to the thousands of prospecting gold diggers. Gold-bearing quartz reefs and lodes were discovered, but it was predicted that these could not be mined economically. Theory also predicted that the reef gold would not continue to depth. Practical observations and mining experience from the numerous discoveries led to revision of the widely held dicta on gold occurrence. Alluvial gold was found in a range of settings, including the recent drainage and ancient and buried leads. A wider variety of rock types was recognised as favourable for gold. Different styles of reef gold were identified and found to be economically mineable to great depth. Evolving ideas on the origin of gold deposits were widely discussed, tested, and refined. Of the many players involved in the early discovery of gold in Australia, Clarke, Hargraves and Murchison probably had the greatest overall influence in terms of theoretical predication and practical outcomes that initiated the Australian gold-mining industry.

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