Co-sampled fruticose and foliose epiphytic lichens as spatial biomonitors of airborne mercury and arsenic in a historical “Gold Rush” mining district

This study examined the spatial distribution of total mercury (THg) and total arsenic (TAs) in water, soil and cassava (Manihot esculenta) (leaves and roots) samples taken from areas in Rwamagasa village in northwestern Tanzania where daily living activities occur in close proximity to extensive artisanal and small scale gold mining. Results indicated that 33.3 % of the water sources had THg levels above the WHO guideline of 1.0 µg/L for safe drinking water, and 12.5 % had TAs levels above 10 µg/L. Cassava leaves were found to have higher THg (ranging from 8.3 to 167 µg/kg) and TAs (ranging from 60 to 1,120 µg/kg) levels than cassava roots, which ranged between 1.2-8.3 µg/kg for THg and 25-310 µg/kg for TAs. Concentrations of THg and TAs in soil samples ranged between 5.8-1,759 and 183-20,298 µg/kg, respectively. Both THg and TAs were found to be distributed throughout Rwamagasa village.

Arsenic and mercury contamination and complex aquatic bioindicator responses to historical gold mining and modern watershed stressors in urban Nova Scotia, Canada

Historical gold mining operations between the 1860s and 1940s have left substantial quantities of arsenic- and mercury-rich tailings near abandoned mines in remote and urban areas of Nova Scotia, Canada. Large amounts of materials from the tailings have entered the surface waters of downstream aquatic ecosystems at concentrations that present a risk to benthos. We used paleolimnological approaches to examine long-term trends in sedimentary metal(loid) concentrations, assess potential sediment toxicity, and determine if geochemical recovery has occurred at four lakes located downstream of three productive gold-mining districts. During the historical mining era, sedimentary total arsenic and mercury concentrations and enrichment factors increased substantially at all downstream lakes that received inputs from tailings. Similarly, chromium, lead, and zinc concentrations increased in the sediments after mining activities began and the urbanization that followed. The calculated probable effects of concentration quotients (PEC-Qs) for sediments exceeded the probable biological effects threshold (PEC-Q > 2) during the mining era. Although sedimentary metal(loid) concentrations have decreased for most elements in recent sediments, relatively higher PEC-Q and continued exceedance of Canadian Interim Sediment Quality Guidelines suggest that complete geochemical recovery has not occurred. It is likely that surface runoff from tailing fields, urbanization, and climate-mediated changes are impacting geochemical recovery trajectories.

Disturbed land rehabilitation in Lynx Creek watershed

Assessing and reducing risks at the Montague and Goldenville gold districts in Nova Scotia

Historic gold and coal mines in the same catchment near Reefton, New Zealand allow comparison of environmental effects of the different mines in the same climate and topography. Gold mine discharge waters (neutral pH) deposit hydrated iron oxide (HFO) abundantly at mine entrances, whereas coal mine discharge waters (low pH) precipitate HFO tens to hundreds of metres downstream as pH rises. Waters leaving historic mines have up to 59 mg L-1 dissolved arsenic, and HFO at gold mines has up to 20 wt% arsenic. Coal mine discharge waters have low dissolved arsenic (typically near 0.01 mg L-1) and HFO has <0.2 wt% arsenic. Minor dissolved Cu, Cr, Ni, and Zn are being leached from background host rocks by acid solutions during sulfide oxidation, and attenuated by HFO downstream of both gold and coal mines. A net flux of 30 mg s-1 arsenic is leaving the catchment, and nearly all of this arsenic flux is from the gold mining area, but >90% of that flux is from background sources. The present study demonstrates that elevated trace metal concentrations around mines in a wet climate are principally from non-anthropogenic sources and are readily attenuated by natural processes.

Past investigations at historical gold (Au) districts in Nova Scotia, Canada have identified elevated concentrations of arsenic (As) and mercury (Hg) in nearby sediments and waters. These metal(loid)s are derived from erosion of mineralized bedrock, and the disposal of mine tailings into the environment during early operations. The Wine Harbour gold district is located along the eastern shore of Nova Scotia, and produced 1329 kg of Au from 75 581 tonnes of crushed rock from 1862 to 1939.The gold occurs in arsenopyrite-bearing quartz-carbonate veins and was extracted using stamp milling and Hg amalgamation. Historical maps document tailings deposits near former stamp mill sites; however, the extent to which these mine wastes influence environmental quality in the adjacent marine environment is uncertain. In this study, we measured metal(loid) concentrations in tailings, marine sediments, and surface waters to assess the lateral and vertical extent of mining-related impacts on Wine Harbour. Chemical analyses of terrestrial and intertidal tailings reveal high concentrations of both As (86–196 000 mg/kg) and Hg (444–320 000 µg/kg). Analyses of marine sediments show a wide range in both As (4–568 mg/kg) and Hg (<5–7430 µg/kg) concentrations. In general, the highest metal(loid) concentrations in sediments were recorded down-gradient of stamp mill sites. Elevated concentrations were also detected in sediments underlying an active mussel aquaculture operation at the western end of the harbour. Results from this study have been used to help assess potential ecosystem and human health risks associated with historical gold mine wastes in the Wine Harbour area.

A comprehensive analysis of the associations between the consumptions of 17 food products with urinary concentrations of arsenobetaine, total arsenic, arsenous acid, dimethylarsinic acid (UDMA), monomethylarsonic acid (UMMA), and total inorganic arsenic for US children aged 3-5 years (N = 439), children aged 6-11 years (N = 2139), adolescents aged 12-19 years (N = 2434), and adults aged >= 20 years (N = 10902) was conducted. Data from National Health and Nutrition Examination Survey for 2005-2016 were used for this study. Concentrations of arsenobetaine were as much as > 15 times higher among consumers of fish/shellfish than non-consumers for children aged 6-11 years, > 12 times higher for children aged 3-5 years, > 13 times higher for adolescents, and > 7 times higher for adults. Consumption of rice as opposed to non-consumption of rice was associated with as much as 36.5% higher concentrations of total arsenic, 12.7% higher concentrations of arsenous acid, 43.9% higher concentrations of UDMA, 18.2% higher concentrations of UMMA, and 14.1% higher concentrations of total inorganic arsenic. Thus, consumption of fish/shell fish and rice was associated with higher concentrations of organic/inorganic arsenic. In addition, consumption of alcohol was also found to be associated with higher concentrations of organic/inorganic arsenic. However, consumption of milk and milk products, vegetables, organ and other meats, and nutritional drinks was found to be associated with lower concentrations of organic/inorganic arsenic. Thus, while consumption of several foods is associated with higher concentrations of arsenic, there are also foods whose consumption is associated with decreased concentrations of arsenic. Further studies are needed to identify foods that may lead to decreased concentrations of arsenic and as such arsenic toxicity.

The Jiapigou gold mine area, located in the upper reaches of the Songhua River, was the first and largest artisanal gold mine once in China, and it used to be prominent in two marking years (1870 and 1974). Jiapigou area had a gold mining history of more than 190 years, which was first opened in 1820. Gold extraction with algamation was applied as the dominant method of excavation from 1940 to 2008, and a total of more than 100 t of gold were extracted from the mine using this method and it was estimated that 100–200 t Hg were released, thus causing severe mercury environmental pollution in the mining area. In the experimental campaigns of this study, in situ air and soil Hg concentrations and air-soil Hg fluxes were measured from April 2009 to December 2011. The results showed that in the study area the total gaseous mercury (TGM) concentration exhibited remarkable spatial and temporal distribution patterns, i.e. the TGM gradually decreased following the increase in distance to gold mining sites in space, and the values in spring, summer and autumn were elevated by 1–2 orders of magnitude in comparison with those in winter. Furthermore, at other sampling sites the total soil mercury (TSM) concentration in spring was higher than that in autumn, except for the contrary laws demonstrated at the Erdaogou mining site. However, in spring and winter the Hg flux between air and soil was under the control of different environmental factors, and the characteristics were clear and distinct. In spring the Hg flux between air and soil was directly under the control of solar irradiation, and the releasing process was predominant with a remarkable positive correlation to solar irradiation. Nevertheless, in winter the Hg fluxes were indirectly under the control of solar irradiation, which caused thermal inversion due to the thick snow cover. The depositing process was predominant and the correlations between Hg flux and air temperature was remarkably negative, and there was a positive correlation between Hg flux and solar irradiation.

Surficial geochemistry and bioaccessibility of tellurium in semiarid mine tailings

Health and ecological risks associated with the use of mercury in gold mining are well known, with much recent attention focussed on contemporary small-scale artisanal mining. Legacy tailings from historical gold mining may also present ongoing risks, as the industry used large quantities of mercury with minimal environmental regulation to limit its discharge. This occurred in both alluvial (placer) mining and in processing auriferous ores. Analysis of historical data on mercury use in the mining industry in Victoria, Australia, indicates that at least 131 tonnes of elemental mercury were discharged into the environment as mine tailings between 1868–1888, with the total amount lost over the historic mining period likely to be much higher. The processing of pyritic ores also concentrated mercury losses in a small number of mining centres, including Bendigo, Ballarat, Castlemaine, Clunes, Maldon and Walhalla. This analysis provides a basis for further research needed to support improved management of legacy mine tailings.

Vertical distribution and mercury speciation in soil profiles were studied to evaluate the extent of contamination and potential Hg mobility in a historical Hg mining area. Three sites were chosen for a case study of Hg contamination. One site was considered a low impact site located 400 m uphill from the mining activities and two sites were located in a presumably more highly impacted area. Mercury speciation was determined by thermo-desorption analysis. High impact soils in a close vicinity of the mine shaft exhibited relatively high Hg concentrations ranging from 8 to 10 μg g−1 in the surface (Ah) horizons and from 3 to 9 μg g−1 in the underlying mineral soils. Approximately 50–80% of total Hg in all soil horizons of high impact soils was present as relatively insoluble HgS. The remaining 20–50% of total Hg was attributed to Hg adsorbed on mineral surfaces, Fe-oxyhydroxides or clay minerals. The highest Hg concentration in the low impact soils was detected in the Ah horizon (7 μg g−1). Mineral soil horizons contained relatively low Hg concentrations (≤0.6 μg g−1). Over 40% of total Hg in the Ah horizon of the low impact soils was HgS, likely deposited as fine particles derived from past mining activities. The Hg in mineral horizons of low impact soils was exclusively Hg(II) weakly bound to mineral particles. Our study indicated that HgS contamination in the vicinity of a former mining area occurs in most Ah horizons of the area, but contamination of mineral soil horizons appears to be limited to the sites downhill from the mine shaft.

Research Article| January 01, 2014 Arsenic Associated with Historical Gold Mining in the Sierra Nevada Foothills: Case Study and Field Trip Guide for Empire Mine State Historic Park, California Charles N. Alpers; Charles N. Alpers U.S. Geological Survey, California Water Science Center, Sacramento, California, U.S.A., cnalpers@usgs.gov Search for other works by this author on: GSW Google Scholar Perry A. Myers; Perry A. Myers California Department of Toxic Substances Control, Sacramento, California, U.S.A. Search for other works by this author on: GSW Google Scholar Daniel Millsap; Daniel Millsap California Department of Parks and Recreation, Sacramento, California, U.S.A. Search for other works by this author on: GSW Google Scholar Tamsen Burlak Regnier Tamsen Burlak Regnier Clean Harbors, San Diego, California, U.S.A. Search for other works by this author on: GSW Google Scholar Reviews in Mineralogy and Geochemistry (2014) 79 (1): 553–587. https://doi.org/10.2138/rmg.2014.79.13 Article history first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Charles N. Alpers, Perry A. Myers, Daniel Millsap, Tamsen Burlak Regnier; Arsenic Associated with Historical Gold Mining in the Sierra Nevada Foothills: Case Study and Field Trip Guide for Empire Mine State Historic Park, California. Reviews in Mineralogy and Geochemistry 2014;; 79 (1): 553–587. doi: https://doi.org/10.2138/rmg.2014.79.13 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyReviews in Mineralogy and Geochemistry Search Advanced Search The Empire Mine, together with other mines in the Grass Valley mining district, produced at least 21.3 million troy ounces (663 tonnes) of gold (Au) during the 1850s through the 1950s, making it the most productive hardrock Au mining district in California history (Clark 1970). The Empire Mine State Historic Park (Empire Mine SHP or EMSHP), established in 1975, provides the public with an opportunity to see many well-preserved features of the historic mining and mineral processing operations (CDPR 2014a). A legacy of Au mining at Empire Mine and elsewhere is contamination of mine wastes and... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Little is known about the variation of Chinese children's exposure to arsenic by geography, age, gender, and other potential factors. The main objective of this study was to investigate the total arsenic concentration in Chinese children's urine by geographic locations, ages, and genders. In total, 259 24-h urine samples were collected from 210 2- to 12-year-old children in China and analyzed for total arsenic and creatinine concentrations. The results showed that the upper limit (upper limit of the 90% confidence interval for the 97.5 fractile) was 27.51µg/L or 55.88µg/g creatinine for Chinese children. The total urinary arsenic levels were significantly different for children in Guangdong, Hubei, and Gansu provinces (P<0.05), where the upper limits were 24.29, 58.70, and 44.29µg/g creatinine, respectively. In addition, the total urinary arsenic levels were higher for 2- to 7-year-old children than for 7- to 12-year-old children (P<0.05; the upper limits were 59.06 and 44.29µg/g creatinine, respectively) and higher for rural children than for urban children (P<0.05; the upper limits were 59.06 and 50.44µg/g creatinine, respectively). The total urinary arsenic levels for boys were not significantly different from those for girls (P>0.05), although the level for boys (the upper limit was 59.30µg/g) was slightly higher than that for girls (the upper limit was 58.64µg/g creatinine). Because the total urinary arsenic concentrations are significantly different for general populations of children in different locations and age groups, the reference level of total urinary arsenic might be dependent on the geographic site and the child's age.

Gold mining in Nova Scotia dates back to the mid-1800s. Historical industrial practices generated over 3 000 000 tonnes of finely ground mine wastes (tailings), the majority of which were deposited into lakes, streams, wetlands, and low-lying areas close to the mill sites. These legacy tailings typically contain high concentrations of mercury (Hg) and arsenic (As) and continue to impact downstream environments to this day. The objective of this review is to critically examine and summarize existing knowledge on the transfer and bioaccumulation of Hg and As in aquatic and terrestrial organisms exposed to legacy gold mine tailings in Nova Scotia. This review reveals that as of mid-2019, 23 previous studies have been completed on this subject. Several of these studies were based on small sample sizes, or had other limitations, such as missing identification of biological species. Despite these limitations, the data in these publications clearly indicate that both Hg and As from abandoned gold mine sites in Nova Scotia are bioaccumulating in plants, fungi, freshwater and terrestrial invertebrates, marine mollusks, amphibians, fish, and mammals. In many cases, concentrations of MeHg exceed Canadian Council of Ministers of the Environment safety guideline values for consumption of wildlife; however, no guideline values are in place for either total Hg or As. No studies were found examining tailings-related Hg or As accumulation in lichen, reptiles, birds, or large mammals. This review concludes that further research on bioaccumulation and biomagnification of tailings-related Hg and As is needed to understand the overall impact of historical tailings on the aquatic and terrestrial ecosystems and species of Nova Scotia. More detailed studies are vital for guiding risk-management decisions and future land-use practices for these contaminated sites.