Tesi sul tema "Golo River"

The Golo River in Corsica, France, is a short, steep river (~95 km, 2706 m relief) in the Western Mediterranean with formerly glaciated headwaters. The small size and location of the Golo River make this system ideal for observing the influence of climate and sea-level change on river dynamics over the 100,000 years. A rapidly advancing dating technique, optically stimulated luminescence, was utilized to determine the timing of these river deposits on the coastal plain in order to frame them in the context of previous glacial and interglacial episodes. Climate fluctuations in the headwaters supplied the vast majority of sediment into the system during glacial time periods, which was then transported and deposited near the mouth of the Golo River on the coastal Marana Plain. Sea- level also played a vital role in defining a geometric configuration that ultimately governed whether large amounts of sediment stored onshore or offshore. Analysis of the Golo River longitudinal profile and watershed reveals changes in steepness and gradient that are related to changes in rock type, fault movement and tectonically-driven base-level fall.

The Wind River gold prospect is located in TSN, R7E of Skamania County, Washington, and is an epithermal gold-quartz vein system hosted in volcanic rocks of the Ohanapecosh Formation, a late Eocene to middle Oligocene unit of calcalkaline chemical composition. Andesitic pyroclastic rocks of the Ohanapecosh Formation are the host of mineralization in the study area, and form the lowest of several stratigraphic subunits. These pyroclastic rocks are overlain by two sequences of lava flows which cap the ridges and are folded by an anticlinal warp over the length of Paradise Ridge, plunging gently to the southeast. Toward the west, the number of flows decreases and the proportion of intercalated pyroclastic rocks increases. Numerous dikes cut the pyroclastic rocks at the Wind River prospect. Geochemical data show these dikes to have been feeders for the overlying lava flows. Differing degrees of alteration of the dikes relative to the most intensely altered pyroclastic rocks which they cut indicates a complex history of overlapping hydrothermal and volcanic activity at the prospect.

The compositions, in terms of Au, Ag, Cu, and Hg, of about 1200 placer and lode gold grains from the Fraser River drainage were determined by microprobe analysis. The lode samples are from the Bralorne and Cariboo Gold Quartz mines. Seventeen placer samples are from the Cariboo district and the Bridge River, Fraser River and their tributaries. Bralorne gold and many placer grains contain Hg which ranges up to 6%. Evidence is presented to show that this Hg is primary. Placer gold grains also contain Cu, ranging up to 31%, but high-Cu gold has little Ag or Hg. The compositional data were used to define populations on Hg-Cu-Fineness plots for each sample location. A comparison of the populations shows that placers located near lodes reflect these sources but that simple downstream transport of the gold cannot explain the populations found far from known sources. In order to explain the population found in downstream placers it is necessary to postulate contributions from undiscovered lodes, fossil placers, or other unknown sources. Many placer grains from the Fraser River have rims that are nearly pure gold. The rimming is thought to have taken place in an "intermediate collector" (fossil placer?) by leaching of Ag. Rimmed gold is not found in the Bridge River. From the data on the composition of the gold one is able to divide the Fraser River drainage into two metallogenic provinces: a Cu-Hg-rich province that includes the Bridge River drainage and a Cu-Hg-poor province typified by the Cariboo region. The data from the lode deposits suggest that the deposits can not only be uniquely characterized but that it may be possible to distinguish zoning within the lodes. In addition, it appears that much of the Cu- and Hg-rich gold is associated with ultrabasic rocks and major faults.
Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate

The problems encountered by mineral explorationists when sampling stream sediments for gold were investigated by considering the sparsity of free gold particles and their tendency to form small placers at certain locations in the stream bed. Fourteen 20-kg samples of -5-mm sediment were collected from contrasting energy and geochemical environments in five streams draining gold occurrences in southern British Columbia. The samples were sieved to six size fractions (420 µm to 52 µm) and gold content was determined by neutron activation analysis following preparation of two density fractions using methylene iodide. Gold concentrations were converted to estimated number of free gold particles and the Poisson probability distribution was used to show that much larger field samples (>100 kg of -1 mm screened sediment) would be required to reduce random variability due to nugget effects to acceptable levels. However, in a comparison of conventional sampling methods, the lowest probability of failing to detect a stream sediment gold anomaly is obtained using the sampling method described in this study. Small-scale placer formation was investigated by collecting twenty 60-kg samples of -2-mm sediment from ten locations along five kilometres of Harris Creek in the Okanagan region, east of Vernon. Samples were prepared and analysed as described above though heavy-mineral concentrates were only prepared for two size fractions. Gold was found to be considerably enriched in sandy-gravel deposits compared to sand deposits, with the effect decreasing as sediment size decreased. The level of enrichment varies on the stream in response to changing channel slope and local hydraulic conditions. Gold anomaly dilution is apparent in sand deposits but not apparent in sandy-gravel deposits since gold is preferentially deposited in gravels as channel slope decreases. These results are presented in the framework of H.A. Einstein's sediment transport model. Sediment collected from gravels may represent the best geochemical sample since placer-forming processes produce high gold concentrations, however in very high energy streams, the small quantities of fine sediment in gravels may lead to unacceptable nugget effects. In the latter case, a sample collected from a sand deposit is a satisfactory alternative.
Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate

Improved technologies, increases in global demand for metals, and lax environmental policies and regulations are causing a shift of large-scale mining activities to the tropics. This shift of mining to the tropics has the potential to modify natural ecosystems and disrupt the social structures of rural and indigenous peoples in some of the most remote areas of the planet. This thesis encompasses research done in two villages of Guyana's Essequibo River basin after the 1995 Omai cyanide spill, and illustrates the local social consequences of a large-scale gold mining operation in the tropics. It documents not only the degradation of the local river ecology, but also the changes in local people's perceptions of their environment. That environment, once viewed as pristine, is now viewed as unsafe, leading to disrupted livelihoods and lifestyles. The finding of this study points to a direct link between international economic liberalization policies (which emphasize privatization, foreign direct investment, and economic growth) and the creation of disaster circumstances in developing countries. This thesis research is the result of a total of ten weeks of participant observer research in the area of the Essequibo River, Guyana. It utilizes the methodology of taped interviews of head-of-households. Interviews were conducted with approximately 85 percent of heads-of household of the villages of Rockstone and Riversview. Additionally, interviews were conducted with national and regional governmental officials, regional health officials, local and indigenous leaders, personnel of the Guyana Geology and Mines Commission, and the Environmental Protection Agency in Guyana. Interviews were supplemented with archival research. The findings of this thesis research closely mirror those of other researchers who contend that the social impacts of technological disasters are long-term and more severe than those related to natural disasters. Seven years after the cyanide spill, disruptions in livelihood activities, diet, and household behaviors continued to be evident in the two villages. There is little indication that the high negative perceptions of the villagers as a result of the disaster will change in the near future. The research found that macroeconomic policies, crafted by national governments and overseen by international financial institutions without the involvement of local citizenry, disproportionately affected the poor and rural populations through the degradation of local ecosystems. The thesis also illustrates the usefulness of ethnographic research-in particular, interviews in disaster studies of developing countries.
Master of Science

Orogenic gold mineralisation in schist terranes with few or no contemporaneous igneous intrusions is poorly understood. It is proposed in this thesis that the structural evolution of such terranes controls the generation of hydrothermal fluid pathways and thus the location of orogenic mineral deposits. Gold mineralisation in the Otago Schist, New Zealand and the Klondike Schist, Canada occurred in the latter phases of greenschist facies metamorphism as well as after metamorphism during Paleozoic-Mesozoic exhumation. In Otago, gold mineralisation occurred at a number of different times and structural levels as the schist belt was exhumed and rocks were brought up through the brittle-ductile transition. In Klondike Schist, gold mineralisation occurred in relatively brittle rocks after a period of regional compression and crustal shortening caused by the stacking of thrust sheets. Gold mineralisation in both schist belts is not associated with any coeval igneous activity. The earliest stage of gold mineralisation in the Otago Schist occurred in the Jurassic when mineralising fluids were progressively focussed into late metamorphic ductile shear zones such as the Hyde-Macraes Shear Zone (HMSZ), east Otago and Rise and Shine Shear Zone (RSSZ), central Otago. Both of these gold-bearing mineralised zones occur along mappable structural discontinuities or boundaries that separate structurally, metamorphically and lithologically distinct blocks. The HMSZ occurs in the hangingwall of an underlying low angle normal fault that juxtaposes mineralised lower greenschist facies rocks on to unmineralised upper greenschist facies rock. The RSSZ occurs in the footwall of an overlying low angle normal fault that juxtaposes unmineralised lower greenschist facies rocks on to mineralised upper greenschist facies rock. The two shear zones did not form as part of a single homogeneous structure. There are several other prospective late metamorphic boundaries that are different from later brittle faults that disrupt the schist. Late metamorphic gold mineralisation is characterised by both ductile and brittle structures, foliation-parallel shears, disseminated gold with sulphides in deformed schist and minor steeply dipping extensional veins. This style of mineralisation is the most prospective but can be subtle in areas without quartz veins. Hydrothermally altered rocks are enriched in gold, arsenic, tungsten and sulphur with minor enrichment of bismuth, antimony, mercury and molybdenum. Disseminated mineralisation in the HMSZ is associated with hydrothermal graphite however there is no hydrothermal graphite in the RSSZ. The next stage of gold mineralisation occurred in the Cretaceous during post-metamorphic exhumation of the schist belt and is characterised by steeply dipping, fault-controlled quartz veins, silicified breccias and negligible wall rock alteration. Most post-metamorphic veins strike northwest such as the ~25 km long Taieri river gold vein swarm, but there are other stibnite and gold mineralised structures that strike northeast (e.g., Manuherikia Fault system) and east-west (e.g., Old Man Range vein systems). The latest recognised stage of gold mineralisation is controlled by structures related to the initiation of the Alpine Fault in the Miocene and is characterised by steeply dipping quartz veins with abundant ankeritic carbonate in veins and ankeritic carbonate with gold in altered rocks. Hydrothermally altered rocks are enriched in arsenic, carbon dioxide and sulphur with minor enrichment of antimony. Gold-bearing veins at Bullendale, central Otago are of this type and are associated with a broad alteration zone. Gold-silver and gold-silver-mercury alloys occur in both Caples and Torlesse Terranes of the Otago Schist. Almost all mercury-bearing gold occurs in east Otago vein systems and mercury-free gold occurs in central and northwest Otago veins, irrespective of host terrane. There is no relationship between depth of vein emplacement and mercury content of gold. The Klondike Schist was emplaced as a series of stacked thrust slices in the Jurassic and thrust-related fabrics are preserved in all thrust slices. Strongly deformed carbonaceous schist horizons are spatially associated with thrust faults and graphite within these units is concentrated along spaced cleavage surfaces. Kink folding is best developed in the uppermost slices of Klondike Schist and overprints thrust-related fabrics. Gold-bearing veins formed in extension fractures controlled principally by pre-existing weaknesses such as kink fold axial surfaces. Normal faults correlated with a period of Late Cretaceous regional extension crosscut kink folds and offset gold mineralised veins. The main stage of mineralisation occurred after major regional compression and thrust stacking and before Cretaceous normal faulting. Gold-bearing veins are widely dispersed throughout the uppermost slices of Klondike Schist and are considered to be a sufficient source for Klondike gold placer deposits. Disseminated gold with pyrite is associated with gold-bearing veins in some Klondike Schist and this disseminated mineralisation expands the exploration target for these veins. Disseminated gold with pyrite, without quartz veins, occurs in some schist lithologies and is associated with chlorite alteration and weak silicification. The arsenic content of gold-mineralised Klondike Schist is much lower than mineralised Otago Schist and background concentrations of arsenic are much lower in Klondike Schist as well. No shear-related mineralisation has been discovered in Klondike Schist but due to its relatively poor exposure, this belt remains prospective for this style of mineralisation.

Master of Science
Civil Engineering
David R. Steward
With an increasing population, municipalities in the United States are struggling to secure safe, reliable water sources for future water demands. Alternative water sources are being considered to improve the overall water management picture. Wastewater reuse, reusing wastewater effluent for beneficial purposes, is an alternative water source that is gaining popularity in the United States. In this study a theoretical framework was developed to enable a region to quickly assess the feasibility of reusing wastewater for irrigation needs. Three criteria were established for the framework; they are, regulations and guidelines for reuse, adequate flow ratio, and cost benefit analysis. As a region moves through the framework and criteria a list of feasible wastewater facilities and end users are established. A model was developed for the cost benefit analysis based on regional input. As regulatory frameworks and economic factors evolve over time the model can be updated to assess how these changes will affect water reuse in a region. The model will provide a useful tool for a region to integrate wastewater reuse into the water resource management process. The Lower Arkansas River Basin (LARK) was highlighted by the Kansas Water Office as a region that should investigate the role of reuse in water conservation. Results from this report indicate 963 million gallons per year (MG/yr) of wastewater effluent could feasibly be used to irrigate 9 hole and 18 hole golf courses in the region. The results determined that any 18 hole golf course within a 15.9 mile radius of a wastewater treatment facility in the LARK could payback the capital costs for wastewater reuse within 10 years. This information is a useful tool for the region to start the discussion for implementing wastewater reuse in the region. The results from this report indicate wastewater reuse for golf course irrigation is economically feasible in the LARK. Establishing a safe reliable water source for the future is paramount to the future of Kansas. Future research is needed to determine how the wastewater diversion affects the environmental balance of the permitted discharge location.

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Tese (Doutoramento)
IPEN/T
Escola Politecnica, Universidade de Sao Paulo - POLI/USP

Hydraulic lock structures have been used for hundreds of years to control and maintain water levels in waterways. The most common are gated water regulation structures used to catch and divert water, and form an essential and critical part of many flood control and agricultural schemes. Although there are clear economic advantages to building the structures, they can contribute to major water quality problems for the waterways they influence (i.e. increased residence times and a change in mixing ability). Further, in most cases, the methods previously used to assess how the structures and their operations influence the flow regimes between the two connected systems were limited, thus hydraulic designers rely on simple formulations, existing literature and experience. Consequently, the objectives of this thesis were to undertake a detailed field study and develop a methodology and computer simulation tool to calculate the flow through a hydraulic structure connecting two water bodies so that future designs can be undertaken based upon sound knowledge. To demonstrate the outcomes of this thesis, the methodology and model were applied to an existing hydraulic structure (referred to as Structure C). Structure C is used to connect and exchange water between the tidally dominated section of the Nerang River estuary and an artificial lake system (Burleigh Lakes) on the Gold Coast, Australia. The gates of this structure open four times each day (once during each semi-diurnal tidal phase) and remain open for a period of 2 hours, allowing alternative and partial exchange between the two water bodies. To gain a better understanding of the dynamics of each waterbody under the influence of the structure, a series of detailed field experiments were initially undertaken to understand and quantify the exchange of water and its mixing ability. Tide gauges deployed within the lake indicated a water level change during each opening of up to 22 cm, equating to 413,600 m3 of water entering the lake over the 2 hour discharge period. Salinity profiles showed that the structure permitted the exchange of saline and freshwater between the two systems, during each tidal cycle, in turn maintaining the lake system as a saline (brackish environment). However, the field study also revealed that the controlled exchange of water between the systems perpetuated a permanently stratified environment on both sides of the structure. To simulate the flow dynamics influenced by Structure C, new routines were incorporated into an existing hydrodynamic model (BFHYDRO) within the model's grid and computational code, as part of this thesis. To achieve this, the flow in and out of the hydraulic structure cell (used to represent the hydraulic structure's location within the model grid) was calculated entirely from the local water level gradients on either side of the structure at each time-step, and not prescribed. This was found to be essential for complex tidally-dominated systems, such as the Nerang River. Routines were also developed to replicate the opening and closing times of the gates. Following the development of the methodology, the hydraulic structure cells were tested and applied to simulate the flow through Structure C and the complex exchange between the estuary and lake, in 2 and 3-dimensions. Tests indicated that the opening and closing times of the gates and the calibration of the discharge coefficient (which forms part of the broad-crested weir formula) were the most sensitive parameters to ensure the correct volume of water exchange between the two systems. Statistically, the model-predicted results compared very well with available surface elevation data within the estuary and lake, and thus, quantified the ability of the hydraulic structure cells to simulate the flux between the estuary and lake for each opening. Following the model validation process, results from the existing configuration were compared with hypothetical design alternatives and are documented herein. Further, part of the thesis also explored a practical and effective computer based learning strategy to introduce and teach hydrodynamic and water quality modelling, to the next generation of undergraduate engineering students. To enhance technology transfer a computer based instructional (CBI) aid was specifically developed to assist with the setup, execution and the analysis of models' output, in small easy steps. The CBI aid comprised of a HTML module with links to recorded Lotus Screen cam movie clips. The strategy proved to be a useful and effective approach in assisting the students to complete the project with minimum supervision, and acquire a basic understanding of water quality modelling. Finally, it is anticipated that this new modelling capability and the findings detailed herein will provide managers with a valuable tool to assess the influence of these structures on water circulation for present and future operations within the region. This model can also be set up at other sites to pre-assess various design configurations by predicting changes in current flows, mixing and flushing dynamics that a particular design might achieve, and assist with the selection process before the final selection and construction.

In the canyon where the Fraser River flows through the Cascade mountains, migrating salmon supported a large, dense native population. By 1850 the Hudson’s Bay Company had several forts on other parts of the Fraser River and its tributaries but found the canyon itself inaccessible. Prior to the gold rush, whites rarely ventured there. Discoveries of gold in Fraser River in 1856 drew the attention of outsiders and a rush of miners, and led eventually to permanent white settlement on mainland British Columbia. Contrary to much historiography, these were not foregone results. Instead, the gold rush was a complex process of negotiation and conflict among competing groups as they sought to profit from gold discoveries. The Hudson’s Bay Company sought to gain and retain control of the resource by incorporating it into its trade and by excluding outsiders. But miners arrived by the thousands, and the Company was forced to try to regulate miners’ access to the resource. However, as a group, miners were cohesive and self-reliant; they had little need for outside intervention. The Hudson’s Bay Company was unable to regulate them while pursuing its own ideas of profit. The British government subsequently revoked the Hudson Bay Company’s trade license, and proclaimed British Columbia a colony. In efforts to impose its own ideals of order on the gold fields, the government introduced a new colonial administration which, following a chain of command extending from London through Victoria to the Fraser, sought to organize the population in the spaces of the Fraser Canyon. Government authority was reinforced by the legal system’s flexible responses to the diverse population’s activities it deemed illegal. By studying the interactions of natives, miners, traders, administrators, and the legal system, I have attempted to untangle the ways in which white men negotiated their particular racist and masculinist ideals and sought to impose them in the spaces of the Fraser Canyon.

The intent of this Practicum is to explore the redevelopment of the Windsor Park Golf Course in Winnipeg, Manitoba. This aim was instigated by the release of an Expression of Interest by the City of Winnipeg in the fall of 2011 to sell a number of its publicly owned golf courses of which Windsor Park was named. The land currently occupied by the golf course is rich with natural amenities, which includes a long and contiguous riparian corridor, mature patches of valuable upland forest, and areas of natural drainage. The overarching goal of this practicum is to retain these ecosystem services by implementing best practices that promote a repurposing of existing land use, create a new residential neighbourhood to limit new urban sprawl and enhance accessibility for residents and visitors.

碩士
大葉大學
環境工程學系研究所
107
The purpose of the study is to investigate the disturbed area of the gold mining by using satellite data around the Ongi river, Mongolia. The reason for the study is that the Ongi River plays a significant role concerning the ecological balance of Gobi area. In Mongolia, the mining sector is rapidly developing as one of key economic indicators of country, however, as known mining always induced a negative impact on environment, too. In particular, gold mining is underway and large area of land caused damage from mineral extraction. As consequence, the regional ecological balance is lost and difficult problems happened to animal husbandry and farming activites. Many small rivers have disappeared resulting a serious damage to environment. The major pollution for the rivers from mining is dirt wash accompanied with large quantities consumption of water, especially for gold mining. Mining companies declared that washing method is on nature and “eco-friendly” only without using chemical methods. However, 1m³ dirt washing with 4-12 tons of water consumption will cause a long-term damage to the environment, finally cause destruction of the river. Evidences show that rivers from Khangai to Gobi dried up soon resulting Gobi desertification. Naturally, there is low rainfall and few water yields in Mongolia causes poor natural rehabilitation of land. However, 40% of the total land area has been granted exploration licenses will cause impacts on ecological balance for a long run. Serious of landsat satellite data were used to detect the developing of disturbed land. Comparing the period between 1986 and 2016 a rapid developing damage from 2.79 hectares to 703.9 hectares is shown on Ongi River.

The Ketza River deposit consists of gold-rich, base metal-poor oxidized and unoxidized manto style orebodies and Fe-silicate alteration zones hosted in Early Cambrian limestones, and quartzsulphide veins and stockwork in Late Proterozoic to Eady Cambrian metasedimentary rocks. Sulphide mineralogy in unoxidized mantos, Fe-silicate alteration zones and in veins and stockwork consists mainly of pyrrhotite, pyrite, arsenopyrite, marcasite, and chalcopyrite. Minor amounts of native bismuth are present in all ore types. Gangue minerals are mainly carbonates (calcite and ankerite), and quartz. Additionally, Fe-silicate alteration zones have locally abundant magnetite and Fe-amphibole. The area was affected by two episodes of folding, followed by two of faulting. All units exposed in the area are affected by the deformation. The two phases of folds have coincident, E-W-trending axes, and are distinguished on the basis of their vergence and nature of the axial planar foliation. First phase folds (FO have upright axial-planar foliation (SO, whereas second phase folds (F2) have moderately NE-dipping axial planar foliation (S2) defined by spaced crenulation cleavage. Folding was followed by NNE-directed thrusting, which was in turn followed by doming and extension that produced horsts and grabens. Arsenopyrite geothermometry was performed in ore samples from various locations in the deposit, and yielded 27.4 to 29.4 average atomic % arsenic, corresponding to temperatures below 330°C. ^Ar/^Ar analysis of white mica from a quartz-sulphide vein gives a mid-Cretaceous (108 +/- 0.3 Ma) age for the mineralization that coincides with the emplacement of the Cassiar plutonic suite. Lead isotopic ratios of samples from the different styles of mineralization in the Ketza River deposit plot in overlapping fields, suggesting a genetic relationship between the different ore types. Analyses from carbonate hosted mineralization have a wider spread, suggesting more complex rock-fluid interactions or less homogenization of Pb isotopes. The distribution of orebodies along normal faults and the coincidence of the age of mineralization with the emplacement of a plutonic suite in the region, make the Ketza River deposit a typical intrusion centered sedimentary rock hosted hydrothermal system, with different ore manifestations according to host rock type. However, the central part of the system (the intrusive source of heat, and possibly fluids, metals, and sulphur) is not exposed.

Mercury (Hg) is a globally circulating heavy metal released through both natural and anthropogenic sources. The largest anthropogenic source of mercury to the global atmosphere is artisanal and small-scale gold mining (ASGM). During the ASGM process, miners add elemental mercury to large quantities of sediment or soil in order to create gold-mercury amalgams that separate alluvial gold from the remaining geological host material. Miners then heat the amalgam using a blowtorch or similar device to separate the mercury and gold, exposing themselves to mercury vapor and releasing mercury to the environment. Following amalgam heating, mercury can deposit into aquatic ecosystems. There, anaerobic microorganisms can convert mercury to methylmercury (MeHg), a potent neurotoxin that rapidly accumulates in aquatic food webs. A high concentration of MeHg in fish poses serious human health risks, especially to pregnant women and children.

In Peru’s Region of Madre de Dios (MDD), mercury use for ASGM is widespread due to increasing global demand for gold. This region in the tropical Amazon is one of the world’s most biodiverse ecosystems and home to more than 150,000 Indigenous and non-Indigenous people, 40% of whom live below the poverty level. Recently, people living in the region have become more aware of negative impacts of Hg pollution through popular press. However, there is lack of controlled scientific studies to examine the environmental impacts of Hg from ASGM and subsequent exposures to surrounding communities.

This dissertation addresses four questions in order to better understand how mercury from ASGM impacts environmental health in Madre de Dios: (1) How is mercury distributed along the Madre de Dios River in areas of active ASGM activity, and what is the risk for mercury exposure to downstream communities? (2) How does land use change associated with ASGM activity affect soil-mediated mercury transport in the Colorado River, Madre de Dios, Peru? (3) Can sulfurized carbon be manufactured in a feasible way for developing countries and used to capture mercury during ASGM amalgam burning? (4) What is the mercury methylation potential of easy-to-manufacture spent, sulfurized carbon sorbents?

Despite significant information on the direct health impacts of mercury to ASGM miners, the impact of mercury contamination on downstream communities has not been well characterized, particularly in Madre de Dios. In this area, ASGM has increased significantly since 2000 and has led to substantial political and social controversy. The second chapter of this dissertation examines the spatial distribution and transport of mercury through the Madre de Dios River with distance from ASGM activity. It also characterizes risks for dietary mercury exposure to local residents who depend on fish from the river. River sediment, suspended solids from the water column, and fish samples were collected in 2013 at 62 sites near 17 communities over a 560 km stretch of the Madre de Dios River and its major tributaries. In areas downstream of know ASGM activity, mercury concentrations in sediment, suspended solids and fish within the Madre de Dios River were elevated relative to locations upstream of mining. Fish tissue mercury concentrations were observed at levels representing a public health threat, with greater than one-third of carnivorous fish exceeding the international health standard of 0.5 mg/kg. This research demonstrates that communities located hundreds of kilometers downstream of ASGM activity, including children and indigenous populations who may not be involved in mining, are at risk of dietary mercury exposure that exceed acceptable body burdens.

This research involved extensive field sampling in an active mining region and indicated suspended particulate transport may be an important source of mercury from mining areas to downstream communities. Chapter three of this research focused on understanding how land use changes can influence soil and sediment transport from mining regions. Within the MDD, a large portion of mining in concentrated within the Colorado River watershed. In the Colorado River watershed, mining and deforestation have increased dramatically since the 1980s, largely concentrated in the Puquiri subwatershed. Field sampling in Feb 2015 identified a strong correlation between Hg and suspended solids concentrations, with especially high suspended solids concentrations downstream of ASGM activity. This supported the hypothesis that Mercury transport in this region is facilitated by soil mobilization and runoff. In order to understand how ASGM activity in the Puquiri affects sediment mobilization from the watershed over time, we employed a watershed-scale soil mobilization model using satellite imagery from 1986 to 2014. The model estimated that soil mobilization in the Colorado River watershed increased by 2.5 times during the time period, and increased by six times in the Puquiri subwatershed, leading to between 10 and 60 kg of mercury mobilized in 2014. If deforestation continues at its current exponential rate through 2030, soil and heavy metal mobilization may increase by five times. This research shows that deforestation associated with ASGM in the Colorado River watershed can exacerbate soil mobilization and mercury contamination. While the impacts of mercury and deforestation are often considered separately, here we studied how deforestation associated with ASGM in the Madre de Dios region can significantly increase soil mobilization and mercury transport to downstream communities.

With a substantial portion of mercury releases coming from a non-industrialized process in developing countries, low-cost and low-tech mercury capture is becoming increasingly necessary. While impregnated activated carbon sorbents are well studied for mercury-capture in developed countries and large industrialized settings, there exist few suitable low-cost alternatives for mercury capture from artisanal and small-scale gold mining (ASGM) in developing countries. Chapter four sought to develop an easy-to-manufacture carbon sorbent using elemental sulfur and activated carbon or hardwood-based biochar for potential use during ASGM gold-amalgam heating. Consumer-grade sulfur powder was melted on granular activated carbon or hardwood biochar in a process feasible for a cook stove setting. Activated carbon and biochar were successfully sulfurized to more than 5% sulfur by weight using powdered, elemental sulfur. The sorbent products were tested for elemental mercury sorption from an air gas stream at room temperature. The sulfurized activated carbon achieved higher elemental mercury adsorption capacity in air stream (500 μg Hg m-3, 2 L min-2) relative to unsulfurized activated carbon and sulfurized biochar. Sorption isotherms were used to examine the sorption mechanism, and indicated that likely a pseudo first order reaction was occurring. This research provides a possible option for mercury control by modifying established mercury capture technologies to be easy to manufacture, locally available, and less hazardous to produce.

In Chapter 5 of this research, the sulfurized sorbents were examined further to understand methylation potential in sediment slurries. Anaerobic sediment slurries were constructed to examine methylmercury (MeHg) production of spent sorbents. Five sorbent types with approximately 10 mg/kg Hg each were added to slurries at 5 % by mass. Dissolved mercury was used as a control to simulate atmospheric deposition or highly reactive mercury. After a 5 d incubation at room temperature, MeHg production was ten times greater with low-technology sulfurized sorbents as compared to activated carbon or biochar alone. Sulfurized sorbents leached significantly more mercury than their non-sulfurized counterparts during desorption experiments and led to greater dissolved mercury concentrations. This research shows that low-cost mercury-contaminated sorbents can have unintended consequences with increased MeHg production and potential for more harm to local communities than atmospheric release.

Mercury releases from ASGM are expected to grow, leading to higher concentrations of mercury in the atmosphere that may affect ecosystems throughout the globe. Understanding the importance of mercury from ASGM to toxicity and accumulation requires in depth research on mercury transformations and MeHg production associated with ASGM. This research examines mercury distribution and transport from ASGM active regions. It identifies that deforestation, erosion, and particulate transport play important roles in overall mercury transport, leading to hazardous mercury concentrations downstream of ASGM activity. Effective point-of-use mercury capture technologies would dramatically decrease the mass of mercury released to the environment. The final chapters of this research serve as a proof of concept for using sulfurized activated carbon for mercury capture in developing countries.

Our research team has built strong relationships with several governmental and non-governmental organizations in Peru who will aid in distributing information. This research will provide invaluable environmental health information to residents, inform political intervention, and reveal a new potential avenue for low-cost mercury control.

Dissertation

Thesis (M.Sc.)--York University, 2005. Graduate Programme in Earth and Space Science.
Typescript. Includes bibliographical references (leaves 136-151). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR19718

In the academic literature resource dependent communities have been characterized as principally economic spaces that evolved relative to their socio-economic dependence on a single resource-based industry. Subsequently, as industry restructuring and closure has effected community transition, research emphasis has shifted to the emergence of alternative economic futures for these places. Currently, economic and social renewal in resource dependent communities is typified by sets of locally based strategies that rely on the participation of all community members. However, as recent research positions local actors as catalysts for socio-economic development, very little research has been dedicated to exploring the multiple roles and contributions women make to their households and broader community. By extension, the organization of women's economic lives, particularly in terms of self-employment, has been absent from the discourses surrounding community transition and resilience. In response, my research is rooted in place-based change as a means of highlighting how self-employed women have made use of place-based resources to structure their livelihood strategies. Using personal observation and semi-structured, open-ended interviews with 13 women in Gold River, BC, the purpose of my research was to demonstrate how self-employed women simultaneously shape and are shaped by place. In turn, I demonstrate that women pursue self-employment as a means of fulfilling their requirements for paid work, personal fulfillment, and the flexibility to maintain household and community responsibilities. In the process, self-employed women have made unique contributions to community well-being and to the evolution of place-based identity.

Surface water pollution is prevalent in numerous areas of central Roodepoort mainly due to gold mining activities. The surface water quality for the Bosmontspruit, Russell’s Stream and the New Canada Dam was assessed from October 2010 to March 2011. Physical, chemical and biological characteristics of the water were determined for 8 monitoring points and the results obtained were compared with the In-stream water quality guidelines for the Klip River catchment and the South African Water Quality Guidelines. A trend noticed throughout the sampling period was the non-compliance in the levels of total dissolved solids (TDS) and dissolved oxygen. The results indicated that concentrations of iron, aluminium, nickel, manganese and potassium were above the limit across the Bosmontspruit and Russell’s stream. There was also significant evidence of excessive faecal coliform and ammonium pollution in the Bosmontspruit. During the monitoring period it was noted that water from these streams were utilised for crop irrigation, bathing, livestock and human consumption and may pose a health hazard due to poor water quality.
Environmental Sciences
M.Sc. (Environmental Science)