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Mining Activity (mining + activity)
Selected AbstractsImpact of habitat disturbance in the wetland forests of East Usambara, TanzaniaAFRICAN JOURNAL OF ECOLOGY, Issue 2 2010Ramadhani Senzota Abstract We evaluated habitat characteristics of East Usambara wetland forests. The abundance and species composition in the tree, shrub and herbaceous layers were enumerated in two sets of nested plots, one set in a natural wetland forest and the second in a wetland forest that had been disturbed by small-scale gold mining activities. Each set had thirty-six 1 m × 1 m plots for herbs, inside nine 5 m × 5 m plots for shrubs, in three 20 m × 20 m plots for trees. The habitat profile of herbaceous , shrub , tree layers was found to be sharply different from one obtained in previous studies at the surrounding nonwetland forests as were species composition and abundance. Unlike in the nonwetland forests, the herbaceous layer was thick, the shrub layer very thin and the woody species density and richness much lower. Disturbance significantly reduced woody cover and changed species composition in the herbaceous layer. Recovery of the woody vegetation was low. Wetland forests in the East Usambaras form a small fraction of the total area, but they are a unique biodiversity repository, they appear to be an important carbon dioxide sink and to reserve and purify water. They are sensitive to disturbance and need protection. Résumé Nous avons évalué les caractéristiques de l'habitat des forêts humides d'East Usambara. L'abondance et la composition des espèces dans les étages d'arbres, d'arbustes et d'herbes furent dénombrées dans deux ensembles de parcelles emboitées, un situé dans une forêt humide naturelle, l'autre dans une forêt humide qui avait été perturbée par les activités d'orpaillage à petite échelle. Chaque ensemble se composait de 36 carrés de 1 m² pour les herbes, situés dans neuf carrés de 5 m × 5 m pour les buissons, eux-mêmes situés à l'intérieur de trois carrés de 20 m × 20 m pour les arbres. Le profil des habitats pour les trois couches d'herbes , d'arbustes , d'arbres s'est révélé très différent de celui qui avait été obtenu lors d'études précédentes réalisées dans des forêts environnantes non humides; il en était de même pour la composition et l'abondance des espèces. Contrairement aux forêts non humides, la couche herbeuse était épaisse, la couche des arbustes très claire et la densité et la richesse des espèces ligneuses étaient beaucoup plus faibles. La perturbation avait significativement réduit le couvert ligneux et changé la composition des espèces de l'étage herbacé. La restauration de la végétation ligneuse était faible. Les forêts humides des East Usambara ne constituent qu'une petite fraction de la superficie totale, mais elles sont un sanctuaire unique pour sa biodiversité, elles semblent être un puits de carbone important et aussi retenir et purifier l'eau. Elles sont sensibles à toute perturbation et doivent être protégées. [source] Abandoned artisanal gold mines in the Brazilian Amazon: A legacy of mercury pollutionNATURAL RESOURCES FORUM, Issue 1 2002Marcello M. Veiga The modern gold rush in the Brazilian Amazon attracted millions of people to become artisanal miners in order to escape complete social marginalization. The rudimentary nature of artisanal mining activities often generates a legacy of extensive environmental degradation,both during operations and well after mining activities have ceased. One of the most significant environmental impacts is derived from the use of mercury (Hg), which is illegal for use in gold amalgamation in Brazil, but continues to be the preferred method employed by artisanal gold miners. The general population is unaware of the capricious nature of mercury and artisanal mining activities. Moreover, individuals in positions of political or economic infiuence tend to be negatively biased towards artisanal mining and government policies do not effectively address the realities of these activities. Affected communities have consequently been ignored,and mistrust towards outside parties is high. Not surprisingly, miners are suspicious of and unlikely to employ externally derived solutions to reduce mercury emissions. This article reviews the use of mercury in artisanal mining and highlights the role miners, governments and non-governmental organizations (NGOs) have played in communicating facts, perpetuating myths and deriving solutions for mercury pollution. This article also raises some key concerns that must be addressed to understand the behaviour of mercury in the environment and identifies solutions for problems facing communities where artisanal gold mining operations have been abandoned. [source] Economic and financial aspects of mine closureNATURAL RESOURCES FORUM, Issue 4 2001James R. Kahn Abstract Today, mine reclamation is a key component to a successful mine plan. Most of the industrialized nations have recognized the need to make mining activities relatively environmentally friendly, if they want to continue to benefit from the economic gains from mineral resource development. Countries such as the United States, Canada, Australia and South Africa are leaders in the field and have implemented relatively sophisticated legislation to ensure environmentally correct mine closure. These countries rely on a combination of strict control strategies and economic penalties to ensure compliance. Yet, from the firm's perspective, reclamation activities are counterproductive as they cut into profits. In order to attract economic development and earn much needed economic capital, most of the rest of the world, particularly the developing countries, lack effective mine closure legislation. The traditional command and control type of legislation that is sometimes used is either vague and therefore avoided, or not enforced appropriately, resulting in an undesirable level of environmental degradation. With the use of case studies from Brazil, this article shows that direct controls are effective in some instances and not in others. It proposes that economic and financial tools may be more effective than the traditional direct controls in getting firms to comply with environmental standards, particularly in developing countries where environmental compliance is more difficult to achieve. It explains the use of performance bonding as one type of economic incentive that has proven to be an effective environmental policy in mine planning and closure. The authors additionally push beyond the typical style of performance bonds to introduce a flexible bonding and insurance system that allows governments to maintain strict environmental standards but limits firms financial exposure during the mining process. Such a system learns from the successes of the industrialized countries that use performance bonding and is sensitive to the needs of developing nations to attract investment yet maintain environmental integrity. [source] Recent channel adjustments in alluvial rivers of Tuscany, central ItalyEARTH SURFACE PROCESSES AND LANDFORMS, Issue 6 2003Massimo RinaldiArticle first published online: 19 JUN 200 Abstract Drastic channel adjustments have affected the main alluvial rivers of Tuscany (central Italy) during the 20th century. Bed-level adjustments were identified both by comparing available topographic longitudinal profiles of different years and through field observations. Changes in channel width were investigated by comparing available aerial photographs (1954 and 1993,98). Bed incision represents the dominant type of vertical adjustment, and is generalized along all the fluvial systems investigated. The Arno River system is the most affected by bed-level lowering (up to 9 m), whereas lower incision (generally less than 2 m) is observed along the rivers of the southern part of the region. Human disturbances appear to be the dominant factors of adjustments: the main phase of vertical change occurred during the period 1945,80, in concomitance with the phase of maximum sediment mining activity at the regional scale. The second dominant type of adjustment that involved most of the rivers in the region consists of a narrowing of the active channel. Based on measurements of channel width conducted on aerial photographs, 38% of the reaches analysed experienced a narrowing greater than 50% of the initial channel width. The largest values of channel narrowing were observed along initially braided or sinuous with alternate bars morphologies in the southern portion of the region. A regional scheme of channel adjustments is derived, based on initial channel morphology and on the amounts of incision and narrowing. Different styles of channel adjustments are described. Rivers that were originally sinuous with alternate bars to braided generally became adjusted by a moderate incision and a moderate to intense narrowing; in contrast, sinuous-meandering channels mainly adjusted vertically, with a minor amount of narrowing. Copyright © 2003 John Wiley & Sons, Ltd. [source] Developmental effects of bioaccumulated selenium in eggs and larvae of two salmonid speciesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2005Jodi Holm Abstract Elevated concentrations of Se have been detected in cold, flowing water habitats near uranium and coal mines in Canada. Fish from these systems have concentrations of Se in their tissues that exceed toxic effect thresholds that have been established for warm-water fishes. However, the applicability of toxic effect thresholds and guidelines to cold water, lotic habitats is a matter of contention in the literature since most cases of Se toxicosis have been documented in standing, warm-water systems. To examine the possibility of impaired reproduction in wild rainbow trout (Oncorhynchus mykiss) and brook trout (Salvelinus fontinalis) near coal mining activity in the northeastern slopes region of Alberta, Canada, spawn from both species were collected from exposure and reference sites. Gametes were fertilized in the laboratory, reared to the swim-up stage, and examined for deformities. A significant relationship was observed for rainbow trout between the amount of Se in eggs and the incidence of developmental abnormalities, specifically craniofacial defects, skeletal deformities, and edema. These associations approximate exponential functions with probabilities that 15% of the population would be affected occurring between 8.8 and 10.5 ,g Se per gram of wet egg weight, based on probit analysis. These relationships are similar to those described for centrarchids inhabiting a seleniferous warm-water lake. No such relationships were established for brook trout. [source] Speciation of heavy metals in recent sediments of three coastal ecosystems in the Gulf of Cadiz, Southwest Iberian PeninsulaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2003Veronica Sáenz Abstract A five-step sequential extraction technique was used to determine the partitioning of Cr, Mn, Fe, Cu, Zn, Cd, and Pb among the operative sedimentary phases (exchangeable ions, carbonates, manganese and iron oxides, sulfides and organic matter, and residual minerals) in coastal sediment from three locations in the southwest Iberian Peninsula. Two sites are located close to industrial areas, the salt marshes of the Odiel River and Bay of Cádiz, and one in a nonindustrial area, the Barbate River salt marshes. The Odiel River salt marshes also receive the drainage from mining activities in the Huelva region. In the sediments from the Bay of Cádiz and Barbate River salt marshes, Cr, Cu, Fe, and Zn were extracted from the residual fraction at percentages higher than 60%. In the sediments from the Odiel River salt marshes, concentrations of all the metals, except Cu, zn, and cd, exceeded 60% in the residual fraction as well. In the sediments from the Bay of Cádiz and Barbate River salt marshes, the main bioavailable metals were Mn and Cd; in those from the Odiel River salt marshes, the main bioavailable metals were Zn and Cd, respectively. The environmental risk was determined by employing the environmental risk factor (ERF), defined as ERF = (CSQV , Ci/CSQV), where Ci is the heavy metal concentration in the first four fractions and CSQV is concentration sediment quality value (the highest concentration with no associated biological effect). Our results showed that the sediments from the Cádiz Bay and Barbate River salt marshes do not constitute any environmental risk under the current natural conditions. In contrast, in the Odiel River salt marshes, Cu, Zn, and Pb yielded ERFs of less than zero at several sampling stations and, consequently, pose a potential threat for the organisms in the area. This is a consequence of the high levels of metals in the area derived from the mining activity (pyrite) and industrial activities and the association of these heavy metals with more labile fractions of the sediments. [source] Alluvial records of medieval and prehistoric tin mining on Dartmoor, southwest EnglandGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 3 2004Varyl R. Thorndycraft The role of tin mining in the society of prehistoric Dartmoor and its impact on the local landscape have long been discussed despite equivocal evidence for prehistoric mine sites. A fluvial geomorphological approach, using floodplain stratigraphy, combined with sediment geochemistry and mineralogy, was employed to identify prehistoric tin mining at the catchment scale. Waste sediment, released during hydraulic mining of alluvial tin deposits, caused downstream floodplain aggradation of sands with a diagnostic signature of elevated Sn concentration within the silt fraction. At a palaeochannel site in the Erme Valley, sediment aggradation buried datable peat deposits. A period of aggradation postdating cal. A.D. 1288,1389 is consistent with the 13th century peak in tin production identified in the documentary record. An earlier phase of aggradation, however, occurred between the 4th and 7th centuries A.D., providing evidence of late Roman or early Post Roman tin mining activity on Dartmoor. © 2004 Wiley Periodicals, Inc. [source] Small,scale mining in South Africa: Past, present and futureNATURAL RESOURCES FORUM, Issue 4 2002Nellie Mutemeri Mining is an important part of the South African economy and has been the driver of much of the economic development of the country. However, the small,scale mining subsector still has to realise its full potential. A small,scale mine has been defined as a mining activity employing less than 50 people and with an annual turnover of less than 7.5 million Rand and includes artisanal mines. Small,scale miners are involved in many commodities but there appears to be a bias towards gold, diamonds and quarrying for construction materials, including brickclays. Small,scale mining is regulated by the same legislation (i.e., for the environment, labour, mineral rights, exploration and mining permitting, and skills development) as large,scale mining, though compliance is low, particularly where artisanal mining in concerned. The effective participation of small,scale miners in the mining sector is hampered by their lack of skills, i.e., technical, business and management, and their limited access to mineral deposits, capital and markets. Some of these hindrances have been inherited from the imbalances of the colonial and apartheid eras and continue to act as barriers, making entrance to the industry difficult. For those who have entered the industry out of desperation, as is the case with most artisanal miners, their activities result in negative impacts evident in the inefficient, unsafe and environmentally unfriendly operations. With the advent of the new political dispensation in South Africa, a new era is dawning for the country's small,scale mining subsector. This has resulted in a change of attitude and new government policies which have led to special programmes being put in place to promote the subsector. Intervention strategies for the support of small,scale mining (some of which are already in operation) include programmes for kickstarting mineral beneficiation and value,addition projects, development of appropriate technologies and skills and technology transfer. Proponents of small,scale mining see a well,regulated industry as being the cornerstone of future rural economic development, particularly for previously disadvantaged communities in the poverty nodes. [source] Noninfectious dermatological diseases associated with chronic exposure to mine tailings in a Peruvian districtBRITISH JOURNAL OF DERMATOLOGY, Issue 1 2008W. Ramos Summary Background, Mine tailings are metallic wastes which are deposited in the environment due to mining activity. Long-term exposure to these metals is harmful to human health. Objective, To determine if chronic exposure to mine tailings constitutes a risk factor for the development of dermatological diseases in the district of San Mateo de Huanchor (Lima, Peru). Methods, An observational case,control study was carried out in the communities of Mayoc, Daza and Tamboraque (exposed to mine tailings, case group) located in the district of San Mateo de Huanchor, and also in the communities of Choccna and Caruya (not exposed to mine tailings, control group) located in the same district. Out of 230 adults, 121 were exposed and 109 were not exposed to mine tailings and out of 135 children, 71 were exposed and 64 were not exposed to mine tailings. Results, In the adult group, 71% of the exposed cases had some noninfectious dermatological disease while in the nonexposed group the frequency was 34% [P < 0·001; odds ratio (OR) 5·40; 95% confidence interval (CI) 3·02,9·68]. A statistically significant difference between groups was found for arsenical dermatitis, nonpruritic papulovesicular eruption, atopic dermatitis, contact dermatitis, seborrhoeic dermatitis and xerosis. In the paediatric population, 71 exposed and 64 nonexposed children were evaluated. Sixty-nine per cent of the exposed group had some noninfectious dermatological disease vs. 30% in the nonexposed group (P < 0·001; OR 6·00; 95% CI 2·71,13·31). A statistically significant difference between groups was found for xerosis and atopic dermatitis. Conclusion, Chronic exposure to mine tailings represents a risk factor for development of noninfectious dermatological diseases in both adults and children. [source] | |||||||||||||