Jose M. Azcue

A Protocol for Minimizing Contamination in the Analysis of Trace Metals in Great Lakes Waters

The precautions and procedures aimed at minimizing contamination artifacts during the collection, filtration, and analysis of trace metals in fresh water are described. The techniques for proper decontamination of sample containers and labware and for field blanks are also presented. Samples are obtained using a portable clean laboratory and analyzed in a Class 100 pressurized room. Preliminary results obtained using the protocols described cast doubt on most of the published data on trace metal concentrations in the Great Lakes. The profiles of dissolved metal concentrations in the water column of Lake Ontario show very distinctive source-dependent features obfuscated in earlier studies by poor data quality.

Manual of physico-chemical analysis of aquatic sediments

Introduction, A. Mudroch, J.M. Azcue, and P. Mudroch Measurement of Physical Properties of Sediments, J.B. Percival and P.J. Lindsay Measurement of Eh and pH in Aquatic Sediments, P. Brassard Rapid and Cost-Effective Analysis for Aquatic Sediment Samples by X-Ray Fluorescence Spectrometry, K.F. Maley Determination of Trace Elements in Sediments, G.E.M. Hall Neutron Activation Analysis, J.M. Godoy Determination of Nutrients in Aquatic Sediments, H. Agemian Supercritical Fluid Extraction of Organic Contaminants in Sediments, H.-B. Lee and D.R. Gere Each chapter includes a list of references.

Impact of abandoned mine tailings on the arsenic concentrations in Moira Lake, Ontario

Abstract Arsenic has accumulated in the different compartments of Moira Lake for the last 160 years, since mining and mineral processing began in the area. The annual total fluvial input of arsenic (As) to the lake is approximately 3.5 tonnes. The dissolved As concentrations in the water show seasonal differences, with an average concentration of 62 μg/L during the summer, and 22 μg/L in winter. The As bound to particles represent approximately 8% of the total As burden in the water column. Arsenic bound to the organic humic, fulvic and lipid fractions represents approximately 1% of the total As in Moira Lake waters. The dissolved As profile of interstitial waters are characterized by subsurface maxima with concentrations four to six times greater than the lake waters. Inorganic As makes up the majority of the As in all the porewater profiles examined. The upward diffusion of As-enriched interstitial waters can explain the distribution of As(III) and As(V) in the overlying lake water. The diffusion upward through the hypolimnion of the arsenite originated in the interstitial water explain the thermodynamic disequilibrium in the distribution of As species in the surface waters of Moira Lake.

Effects of abandoned gold mine tailings on the arsenic concentrations in water and sediments of jack of clubs lake, B.C.

Abstract From 1933 to 1964 gold was extracted by underground mining at the northeast shore of Jack of Clubs Lake. At present, tailings and waste rock 4.5 m thick covers approximately 25 hectares of land adjacent to the lake. Arsenic concentrations (>2,000 μg.g‐1) were found in the tailing materials. Two simultaneous processes are controlling the elevated As concentrations in the lake sediments (up to 1,104 μg.g‐1), deposition of suspended particles enriched with As and subsequent diagenetic cycling of sedimentary As. Arsenic concentrations (as high as 556 μg.L‐1) in water samples adjacent to the tailings indicate mobilization of As. However, dissolved As is readily scavenged or coprecipitated with iron hydroxides. The greatest proportion of As in the sediment cores is associated with iron oxides and sulphides. Under oxic conditions the high concentrations of Fe in the tailings is actually beneficial and very effective at limiting the migration of undesirable elements.

Trace elements in water, sediments, porewater, and biota polluted by tailings from an abandoned gold mine in British Columbia, Canada

Abstract The concentrations of major and trace elements in different environmental compartments (e.g., water, suspended and bottom sediments, sediment porewater, and biota) of Jack of Clubs Lake (JCL), Wells, British Columbia (Canada), were determined to assess the biogeochemical effects of abandoned gold mine tailings on the aquatic ecosystem of JCL in the Fraser River drainage basin. Arsenic and Pb were transported from the tailings to the lake, where they accumulated in bottom sediments in concentrations up to 1104 and 281 μ/g, respectively. Although the benthic community in the lake was only partially affected, there was evidence that the tailings inhibited a variety of microbial activities in the lake sediments. The concentrations of As, Cd, Cu and Pb in invertebrates collected from streams flowing through mine tailings, and from vegetation growing on the tailings, suggest a potential for contamination of the food chain of the surrounding ecosystems.

Distribution of Major and Trace Elements in Sediments and Pore Water of Lake Erie

Abstract Concentration profiles of major and trace elements were determined in sediment cores from the Central Basin of Lake Erie. The concentrations of trace elements (As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn) in the sediments were greatest at approximately 18 cm sediment depth, corresponding to the early 1960s. The concentrations of all elements in the sediments have considerably decreased in the last decade. However, the concentrations of Hg, Pb, and Cd are still about 10, 5, and 4 times greater, respec, than those in the pre-industrial sediments. The profiles of dissolved concentrations of the trace ele in pore water were characterized by maxima below the sediment-water interface, dropping off rapidly within the zone of reduced sediments. Concentrations of dissolved trace elements below the sediment-water interface are about one order of magnitude greater than those in the lake water. Conservative estimates of benthic fluxes ranged from 0.04 /μg/cm 2 .y to 194 /μg/cm 2 .y for Cd and Fe, respectively. Upward diffusive remobilization from sediments to lake water is a significant transport process in the Central Basin of Lake Erie and may play an important role in the transport of trace elements from the sediments.

Role of sediment porewater in the cycling of arsenic in a mine-polluted lake

The surficial sediments of Moira Lake average 545 μg.g−1 of arsenic, with maximum values close to 1 mg.g−1 at depths of 23–27 cm below the sediment water interface. The sediment porewater is the linking agent between the sediment solid phase and the overlying lake water. The depth distributions of total As in interstitial waters at all stations are characterized by subsurface maxima, with concentrations four to six times greater than in the lake wates. In all the porewater profiles examined, inorganic As [As(III)+As(V)] comprised most of the As. The As(III) (arsenite) percentage ranged from 66–83%. Methylated-As compounds represented <2% of the total As. The strong correlation of As with Fe and Mn together suggests that both Fe and Mn are involved in the As mobility. The elevated As concentrations in bottom sediments represent a continuous internal mining of As towards the interface all year around. The concentration gradient of total dissolved As indicates that an upward diffusion of As towards the water column with the estimated annual fluxes being 0.8–3.8 μg.cm−2.y−1.

Effects of Past Mining Activities on the Arsenic Concentration in Fish from Moira Lake, Ontario

The effects of the past mining activities on the arsenic (As) concentration in 14 species of fish from Moira Lake, Ontario, Canada, were determined. The lake is characterized by elevated concentrations of As, with up to 106 fig/L in water and 1,000 flg/g in bottom sediments. The mean whole-body concentration of As in 13 of the fish species ranged from 0.03 to 0.34 mg/kg wet weight, whereas that for the creek chub (Semotilus atromaculatus) was 2.4 mg/kg. For rock bass (Ambloplites rupestris), concentrations of As were greatest in the intestine, followed by the bones plus scales. The mean ratio for the liver:muscle As concentration in rock bass (0.53) suggests a relatively low level of As stress. Despite the elevated environmental concentrations of As, and with the exception of creek chub, the tissue residues of As suggest that Moira Lake fish are not under As stress. Moreover, the As concentrations in the fish do not seem to represent a health hazard to local residents that consume fish.