The geochemistry of Fe, Mn, Ni, Cu, Zn and As in the water column, sediments and porewaters in a seasonally anoxic lake (original) (raw)
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Sediment trace metal profiles in lakes of Killarney Park, Canada
Environmental Pollution, 2004
The lakes in Killarney Provincial Park (KPP) located 40e60 km southwest of Sudbury, Ontario are beginning to recover after decades of being severely affected by acidification and atmospheric pollutants. Detailed profiles of acid-recoverable trace elements (As. Cd, Cu, Co. Fe, Mn, Ni, Pb and Zn) were obtained after aqua regia digestion and ICP-OES analysis of sediment cores taken from six Park lakes. Results permitted the identification of two types of profiles. The first type applies to elements such as Fe, Mn, As and Co for which historical deposition and recent recovery are strongly masked by diagenetic remobilization. The second type of profile applies to elements such as Cd, Cu, Ni, Pb and Zn on which the history of industrialisation in North America and mining activities in Sudbury can be superimposed. Based on sediment data of trace elements less affected by diagenetic remobilization (Cd, Cu, Ni, Pb, Zn), chemical recovery indices can be estimated from depth profiles. Indices of maximum (C p ) and surface (C s ) contamination were calculated by dividing the concentration of a given metal by the pre-industrial level. The ratio of the two indices provided a simple estimation of the chemical recovery of lakes that does not consider the influence of the watershed or the lake pH. Profiles of metals in sediment of KPP complement the water quality monitoring data and tend to indicate that this area is in transition from dominant influence of regional pollution sources to becoming controlled by continental atmospheric deposition.
Contrasting sources and mobility of trace metals in recent sediments of western Lake Erie
Journal of Great Lakes Research, 2018
Concentrations of the major and trace metals varied considerably in the western basin of Lake Erie, ranging from 0.9 to 25.3 mg/g for aluminum, from 2.9 to 36.5 mg/g for iron, from 6.4 to 74.8 mg/g for calcium, from 1.2 to 13.5 μg/g for cobalt, from 2.8 to 61.6 μg/g for copper, from 2.7 to 83.0 μg/g for lead, from 0.1 to 2.9 μg/g for cadmium, and from 7.1 to 127.3 μg/g for strontium. Distinct patterns of sediment metal variability allowed the identification of two major fluvial sources and some active in-lake biogeochemical processes. The inputs of Sr were largely from the Maumee River, the inputs of Cu, Pb, Cd, and Co were dominated by the Detroit River, and the inputs of Fe and Al were roughly evenly from the two rivers. The removal of Sr and Ca from the water column was mainly through coprecipitation with calcite. In contrast, the transfer of Cu, Pb, Cd, and Co was largely attributed to the removal of fine sediment particles from the Detroit River mouth and adjacent nearshore areas and the deposition of the metals scavenged by settling organic materials in the basin's central deeper areas. The mobility of the trace metals was different during the in-lake mass transfer, with Co being the most mobile and Cd being the least mobile. Furthermore, the trace metal mobility differences have decreased significantly during the past half-century due to a substantial increase in organic matter from eutrophication in the basin.
Limnology and Oceanography, 1992
Total acid-soluble and dissolved Cd, Co, Cr, Cu, Ni, Pb, and Zn concentrations in the water column of a seasonally anoxic lake (Lake Sammamish, Washington) were measured on a monthly basis during the course of a year. These data, in conjunction with Fe, Mn, sulfide, and nutrient data, are used to assess the biochemical processes controlling the distribution of trace metals in the lake and how the importance of these processes varies with time. Thermodynamic calculations are used to examine changes in dissolved metal speciation in the bottom waters during the year and to assess the saturation state of metal-sulfide phases. Spatial and temporal changes in the redox conditions of the bottom waters result in increases in dissolved Co and Ni concentrations, peaks in particulate Co profiles, decreases in dissolved Cu and Cr concentrations, and significant changes in dissolved metal speciation during stagnation. The rcdox-driven cycling of Fe and Mn in the hypolimnion has a dramatic effect on Co distributions, a slight effect on Ni concentrations, and virtually no effect on Cd, Cu, Cr, and Zn concentrations. Biological uptake and regeneration processes result in a correlation between Zn and silicate concentrations throughout the water column, and it appears that biological cycling may also influence the distribution of Cd. During the sulfidic phase of stagnation dissolved Cd concentrations in the bottom waters may be controlled by metal-sulfide precipitation, Cr(V1) is probably reduced to more particle-reactive Cr(II1) and removed by settling particles, and Cu(H) is most likely reduced to Cu(1) and precipitated as a metal-sulfide phase.
Science of The Total Environment, 1989
Water-column and sediment-trap monitoring programs were used to investigate the important mechanisms regulating the biogeochemical cycling of A1, Fe, Mn, Cd, Cu, Pb and Zn in the acidified and reference basins of Little Rock Lake, an oligotrophic seepage lake in northern Wisconsin. Background lake water concentrations of dissolved (0.4/Jm pore-size filtered samples) metals were ~g 1-1): AI, 7; Fe, 17; Mn, 12; Cd, 0.05; Cu, 0.3; Pb, 0.1; and Zn, 3. The two main basins of the lake were divided by a polyvinyl barrier, and stepwise acidification (2 years each at pH 5.6, 5.1 and 4.6) of the north basin with H2SO4 began shortly after ice-out in April 1985. The south basin (annual average pH6.1) is being maintained as a reference. Of the metals measured in this study, only dissolved Mn increased (from 12 to 30/~g 1-1) when the north basin was acidified from pH 6.1 to 5.6; this was accompanied by a 70% decrease in the sedimentation rate of particulate Mn in this basin. Further acidification of the north basin to pH 5.1 resulted in a further increase in dissolved Mn (from 30 to 40~g 1-1), a twofold increase in dissolved Fe (from 30 to 50/~g 1-1), and a 45% elevation in dissolved A1 (to 15.5/~g 1-1) over reference basin levels (10.7/~g 1-1). No increases in dissolved Cd, Cu, Pb, or Zn were observed in the acidified basin during the first 3 years of acidification. Analysis of suspended particulate matter collected from both basins revealed lower levels of particulate A1, Fe, Mn, and Pb in the acidified basin, demonstrating that metals have reduced affinity for particulate matter at the lower pH of the acidified basin. Enclosure (i.e. limnocorral) experiments in the littoral and pelagic zones of the north basin in 1984 and in 1985 accurately predicted the pH levels at which dissolved A1, Fe, and Mn first increased in this basin.
Role of sediment composition in trace metal distribution in lake sediments
Applied Geochemistry, 2002
Sediment cores were collected from 20 lakes from the Muskoka region of Ontario, Canada, to study vertical changes in trace metal concentrations with depth and the distribution of metals amongst humic material, amorphous and crystalline Fe and Mn oxides, insoluble organics/sulphides, and silicates. Based on their total concentrations, trace elements displayed different degrees of affinity for the organic fraction (represented by organic C) and the mineral fraction (represented by Al). Certain elements (Hg, As, Sb, Pb, Cd, and Zn) displayed a positive correlation with organic C, a negative correlation with Al, and enrichment in surface sediments (with enrichment factors ranging from 2 to 24). Detailed speciation studies revealed that these elements were associated mainly with humic material and to a lesser extent with oxides in surface sediments. Other elements (Al, Cr, Co, Fe, and Mn) displayed a negative correlation with organic C, a positive correlation with Al, and no consistent enrichment in their total concentration at the surface. The speciation study revealed that metals of the latter group were mainly associated with the silicate fraction in both surface and deep sediments. This study shows that relative affinities for organic and mineral fractions play an important role in the distribution of trace metals during burial and diagenesis, and hence in the shape of their vertical profiles.
Temporal and spatial trends in metal loads to sediments of Lake Simcoe, Ontario
Water, Air, & Soil Pollution, 1988
Metal loads to sediments of Lake Simcoe were partitioned into three components, which were attributable to natural background, accelerated erosion, and point + atmospheric sources. These loads were calculated over time using metal concentration profiles together with pre-setttement sedimentation rates based on sonar and time-variable sedimentation rates based on 21°Po profiles in cores. Concentrations of metals significantly higher than pre-settlement concentrations were observed in all cores in the case of Pb, back to 80 yr BP on average, and in at least 75 % of cores, back to 60 yr BP for Cd and Zn and 30 to 45 yr BP for Cu, Ni, and Cr. Total metal loads increased 3 x for Cu and Ni, 4 x for Zn and Cr, 11 x for Cd and nearly 20 x for Pb from pre-1800 to 0 to 10 yr BP. At present about 90% of the anthropogenic loads of Pb and Cd, and 60 to 70}0 of the anthropogenic Cu, Ni, Zn, and Cr, are from point + atmospheric sources, the balance being from increased erosion. The direct atmospheric input of Cd is relatively high, approximately 77% of point + atmospheric inputs, while inputs of Cr and Ni are low at 1% and 9%, and inputs of Cu, Zn, and Pb are intermediate at 20 to 40% of point + atmospheric inputs. Two significant findings on spatial distribution of metals were the large increases in metal loads to Cook Bay following the drainage of 33 km 2 of marshes for agricultural use and the widespread dispersal of Cr from point source(s) in Kempenfelt Bay.
Trace Metal Mineral Equilibria in Lake Erie Sediments
Journal of Great Lakes Research, 1980
3-Mineral equilibria were examined for the system Cd-Pb,Zn-Fe(I1)-CO PO-H 0 in the interstitial waters of the upper meter of Lake Erie sediments. To closely approximate anoxic sediment conditions, extrusion and squeezing 4 2 were performed under a nitrogen atmosphere shortly after coring. Interstitial water concentrations of ferrous iron, zinc, cadmium, lead, and carbonate alkalinity were about a factor of 3-5 greater in the near-shore Ashtabula cores than in the central basin. Pore waters were supersaturated with respect to vivianite (Fe (PO) * 3 4 2 8H20) and siderite (FeC03) which were generally in equilibrium with each other. Cadmium, lead and zinc, however, were undersaturated with respect to carbonate and phosphate minerals phases. Metal concentrations were generally greatest in the 10 cm immediately below the sediment-water interface. Calculations showed 90-98 percent of the lead, 20-60 percent of the zinc, and 5 percent of the cadmium to be inorganically complexed. Organic complexation tied up additional metal and may account for the larger total dissolved metal levels in the upper 10 cm of the sediment pore waters.
Geochemical processes controlling concentrations of Al, Fe, and Mn in Nova Scotia lakes
Limnology and Oceanography, 1990
Concentrations of Al, Fe, Mn, major ions, and dissolved organic C (DOC) were measured in 37 lakes in Halifax County, Nova Scotia, to determine the factors controlling the behavior of these metals in acidic waters with relatively high concentrations of organic matter. Concentrations of trace metals ranged from < 50 to 700 pg liter-l (Al), ~20 to 960 fig liter-' (Fe), and < 10 to 240 pg liter-l (Mn). Concentrations of Fe and Al were highly correlated with H+ ion and DOC concentration, whereas Mn was correlated most strongly with H+ ion concentration and size of catchment relative to lake surface area. Computation of trace-metal speciation indicated that lakes with pH > 5 were in equilibrium with gibbsite and amorphous iron hydroxide but highly supersaturated with respect to manganite and Mn(IV) oxides. Concentrations of Mn appear to be determined by the magnitude of the source (i.e. the catchment area) relative to the size of the lake. In lakes with pH < 5, concentrations of Al and Fe seem to be regulated by interactions with DOC. Although the metals and organic C enter the lake separately, we propose that precipitation of metal humates is the major process regulating concentrations of Al and Fe and, to a lesser extent, DOC in these
Applied Geochemistry, 2014
Drainage from sulfide-rich mine waste can contaminate surface waters directly by surface runoff and indirectly through groundwater discharge. The Camp Lake watershed, located in northern Manitoba, receives both direct and indirect drainage from an abandoned tailings impoundment which has resulted in severely degraded water quality. Sulfide oxidation has been occurring for over 70 years at an abandoned mine site in this watershed, resulting in high concentrations of oxidation products in the surface water and groundwater discharging from the two tailings impoundments, both of which flow into the adjacent Camp Lake. A 5-year hydrological and geochemical sampling program was conducted at this small Precambrian shield lake prior to the initiation of remedial actions, to identify the seasonal distribution and mass-loading of dissolved metals and sulfate discharging from Camp Lake to the downstream Kississing Lake. Weekly and biweekly sampling of outflow from the lake clearly showed a seasonal cycle of dissolved metals, sulfate and pH. During months when the lake was ice-covered, the discharge water had a neutral pH with low concentrations of dissolved metals and sulfate similar to background concentrations. At spring melt the discharge sampled at Camp Weir revealed abrupt increases in dissolved metal and sulfate concentrations and decreases in pH to values that remained relatively constant until fall freeze-up, when dissolved metal concentrations and pH returned to winter values. The annual and interannual variations in loadings measured at Camp Weir are different from those measured at the two streams feeding Camp Lake showing the contribution of groundwater flow through the tailings to SO 4 and metal loadings to the lake during dry years and the potential for significant loadings due to flushing of the thick unsaturated zone in the tailings during relatively wet years. The abrupt changes in pH, metal and sulfate concentrations and the timing of these changes with the appearance and disappearance of ice-cover on the lakes suggests a combination of physical and geochemical controls related to shifts in sources of water, mixing and changes in solubility. Despite fairly low average annual metal concentrations measured in Camp Lake discharge, concentrations of Zn and Cu were elevated above background in bottom sediments of Kississing Lake in a zone extending 9.5 km 2 from the location of Camp Lake inflow. These results show the importance of the open-water period in controlling metal discharge from mine-impacted areas, and demonstrate that even when average annual concentrations are only slightly elevated, long-term metal loadings can have a significant impact on the receiving aquatic systems.
Deposition and chemistry of pollutant metals in lakes around the smelters at Sudbury, Ontario
Environmental Science & Technology, 1982
Analyses of the suspended particulates in lakes within a 30-km radius of the smelting complex at Sudbury show average Ni, Cu, Zn, and Pb concentrations of 1500, 420, 540, and 360 ..mu..g gâ»Â¹, respectively. Organic matter constitutes 35-60% of the suspended material in the lakes but plays a minor role in the transport of metals to the sediments. The rates