scholarly journals Identification and Prioritisation of Mine Pollution Sources in a Temperate Watershed Using Tracer Injection and Synoptic Sampling

Author(s):  
Patrick Byrne ◽  
Alan Yendell ◽  
Ilaria Frau ◽  
Aaron M. L. Todd

AbstractIdentifying and prioritising mine sites for remediation is challenging due to inherently complex hydrological systems and multiple potential sources of mine pollution dispersed across watersheds. Understanding mine pollution dynamics in wet temperate watersheds is particularly challenging due to substantial variability in precipitation and streamflows, which increase the importance of diffuse sources. A tracer dilution and synoptic sampling experiment was conducted in a mined watershed in Scotland to identify the main sources of mine pollution, the relative importance of point and diffuse sources of pollution, and the potential benefits of mine site remediation to stream water quality. Using high spatial resolution metal loading datasets, the major Zn and Cd source areas were identified as point sources of mine water predominantly located in the upper part of the watershed. In contrast, the main sources of Pb were diffuse sources of mine tailings and wastes located in the lower part of the watershed. In the latter case, mobilisation of Pb occurred primarily from a section of braided wetland and an uncapped tailings area. Importantly, diffuse sources of mine pollution were found to be the dominant source of Pb, and an important source of Zn and Cd, even under steady-state streamflow conditions. Mass balance calculations suggest that treatment of the main mine water sources in the upper watershed and capping of the tailings deposit in the lower watershed could reduce stream trace metal concentrations by approximately 70%. These data support the development of conceptual models of mine pollution dynamics in wet temperate watersheds. These conceptual models are important as they: (1) help prioritise those mine sites and features for remediation that will deliver the most environmental and socio-economic benefit, and; (2) provide a means to quantify the importance of diffuse pollution sources that may increase in importance in the future as a result of changes in precipitation patterns in temperate watersheds.

2020 ◽  
Vol 2 ◽  
Author(s):  
Beth Hoagland ◽  
Alexis Navarre-Sitchler ◽  
Rory Cowie ◽  
Kamini Singha

High concentrations of trace metal(loid)s exported from abandoned mine wastes and acid rock drainage pose a risk to the health of aquatic ecosystems. To determine if and when the hyporheic zone mediates metal(loid) export, we investigated the relationship between streamflow, groundwater–stream connectivity, and subsurface metal(loid) concentrations in two ~1-km stream reaches within the Bonita Peak Mining District, a US Environmental Protection Agency Superfund site located near Silverton, Colorado, USA. The hyporheic zones of reaches in two streams—Mineral Creek and Cement Creek—were characterized using a combination of salt-tracer injection tests, transient-storage modeling, and geochemical sampling of the shallow streambed (<0.7 m). Based on these data, we present two conceptual models for subsurface metal(loid) behavior in the hyporheic zones, including (1) well-connected systems characterized by strong hyporheic mixing of infiltrating stream water and upwelling groundwater and (2) poorly connected systems delineated by physical barriers that limit hyporheic mixing. The comparatively large hyporheic zone and high hydraulic conductivities of Mineral Creek created a connected stream–groundwater system, where mixing of oxygen-rich stream water and metal-rich groundwater facilitated the precipitation of metal colloids in the shallow subsurface. In Cement Creek, the precipitation of iron oxides at depth (~0.4 m) created a low-hydraulic-conductivity barrier between surface water and groundwater. Cemented iron oxides were an important regulator of metal(loid) concentrations in this poorly connected stream–groundwater system due to the formation of strong redox gradients induced by a relatively small hyporheic zone and high fluid residence times. A comparison of conceptual models to stream concentration–discharge relationships exhibited a clear link between geochemical processes occurring within the hyporheic zone of the well-connected system and export of particulate Al, Cu, Fe, and Mn, while the poorly connected system did not have a notable influence on metal concentration–discharge trends. Mineral Creek is an example of a hyporheic system that serves as a natural dissolved metal(loid) sink, whereas poorly connected systems such as Cement Creek may require a combination of subsurface remediation of sediments and mitigation of upstream, iron-rich mine drainages to reduce metal export.


1994 ◽  
Vol 30 (5) ◽  
pp. 177-186 ◽  
Author(s):  
Karin Sundblad ◽  
Andrzej Tonderski ◽  
Jacek Rulewski

Nitrogen and phosphorus concentration data representing samples collected once a month for nine months at 13 locations along the Vistula River are considered in a preliminary discussion of the sources of the nutrients transported to the Baltic Sea. Concentrations in relation to flow data indicated substantial differences between subbasins. Based on those differences, on the area-specific nutrient loss for a six-month period and on the wastewater discharge in each subbasin, four regions could be recognized in the river basin: i) the southern region with a large impact of point sources, ii) the south central region, where diffuse sources seemed to be of major importance, iii) the north central region with a combined effect of point and diffuse sources, and retention in two reservoirs, iv) the northern region where point sources seemed to be the dominating source, at least for phosphorus. Our results illustrate the importance of differences in phosphorus retention between the basins. Long-term retention along the course of the river, particularly in the two reservoirs, must be estimated to allow proper source apportionment in the Vistula basin. Concentration decreases in the Wloclawek Reservoir varied between 44 and 68% for P, and 11 to 37% for N, in the months with significant retention. In some months, however, concentrations increased, indicating a release of nutrients.


1998 ◽  
Vol 38 (10) ◽  
pp. 207-214 ◽  
Author(s):  
Sung Ryong Ha ◽  
Dhong Il Jung ◽  
Cho Hee Yoon

Runoff loads of pollutant in agricultural watersheds were spatially analyzed by using geographic information system(GIS) technology. The topological relationship between pollution sources in the watershed was, first of all, identified by using the developed digital map of land use and then the pollutant loads generated from each source was estimated by applying a conventional unit loading factor on the obtained digital information of pollution sources. To evaluate the loads delivered from spatially distributed pollution sources to monitoring stations in down stream via surface of watershed, a renovated empirical model incorporated with the information of pollutant discharge path was developed through introducing a digital terrain model(DTM) technique. In this model, the function of degradation of pollution loads during delivery process was simplified so that each watershed could have a basin-wide self-purification capacity which would be considered to be possessed inherently in each watershed and could retard the discharge of pollutants from sources generated to stream water. Model credibility showed good consistency with comparing the simulated values with observed data. Monte Carlo optimizing technique made it possible to estimate the basin-wide self-purification coefficients.


1996 ◽  
Vol 33 (4-5) ◽  
pp. 137-144 ◽  
Author(s):  
Josef Hejzlar ◽  
Vojtech Vyhnálek ◽  
Jirí Kopácek ◽  
Jirí Duras

Export and sources of P in the Vltava basin (subbasin of upper Elbe: total area – 28,093 km2; population density – 115 km−2; forests – 35%, farmland – 51%) were evaluated during 1972–1993. Annual export rates of total P from the basin to the river Elbe ranged between 38 and 68 kg km−2 a−1. Reservoirs with hydraulic retention times longer than 15 days were efficient traps for phosphorus retaining 20 to 30% of total P loading into the watercourses. Point sources (municipal wastewaters) were most important throughout the period and their share varied from approximately 60% in wet years to more than 90% in dry years. Export from diffuse sources (dominated by output from farmland) was highly dependent on discharge and fluctuaded between 5 and 40 kg km−2 a−1 in dry and wet years, respectively. Only about 2% of the P input into the basin from the fertilisation of farmland and from the atmospheric deposition was exported to the watercourses.


2001 ◽  
Vol 44 (11-12) ◽  
pp. 325-330 ◽  
Author(s):  
H. Obarska-Pempkowiak ◽  
T. Ozimek ◽  
W. Chmiel

Facilities constructed in order to protect streamS against storm water in the Gdan«sk region are described. The first of them is located on the Rynarzewski Stream (water flow 25 l/s). The stream is the main tributary of the Jelitkowski Stream which in turn drains to the Baltic Sea in the area of popular beaches and hotels. Results of analyses indicate the improvement of water quality in the stream and along beaches in this region. Another facility is situated on the Swelina Stream (water flow 30 l/s). The stream is fed with storm water originating from residential districts. In order to improve water quality a pond was constructed supported by a subsurface flow filter (HF-CW type). After implementation of the system substantial improvement of water quality occurred. In order to protect drinking water intake for the city of Gdan«sk against surface and point sources of contaminants a hydrophite treatment system was constructed in Bielkowo. The system consists of two subunits: wet unit (pond), filled with water all the time and dry unit (extention of the pond), designed for storm water. In the wet unit dams constructed of medium size sand are placed. The system, especially the dams, is inhibited with reed. The drainage systems collect water percolating through the dams, and directs it downstream. The system was constructed in 1997. Since then it has proven a substantial improvement of water quality discharged of inflowing loads, on average.


1999 ◽  
Vol 40 (2) ◽  
pp. 11-17 ◽  
Author(s):  
A. Tanik ◽  
B. Beler Baykal ◽  
I. E. Gonenc

Water is supplied in the Greater Istanbul Metropolitan Area from the surface water of six main reservoirs. The present land use in the catchment areas of the reservoirs indicates that the area devoted to agricultural activities and to forests and meadows varies between 73 and 97% and that only a minor percentage, 1-26%, is devoted to settlements and industries. In contrast to the land use profile, the current environmental evaluation of the catchment areas reveals that point sources dominate over diffuse sources. However, this trend is expected to be reversed in the near future, making diffuse sources and control of fertilizers and pesticides the most significant issue. Pollutant loads regarding pesticides and fertilizers are calculated from unit loads based on area. These pollutants are observed to have a negative impact on water quality in terms of eutrophication and toxicity. In this paper, the status of fertilizers and pesticides are addressed and some protective measures for reducing the impact of agricultural pollutants in the reservoirs are recommended.


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