Douglas H. Loring

Lithium — a new approach for the granulometric normalization of trace metal data

Abstract Grain size and provenance are two of the most significant parameters controlling the sedimentary variability of trace metals which must be compensated for by any normalization procedure. Geochemical data show that Li can be used effectively to normalize for the natural granular and mineralogical variability of Cr, Cu, and Zn concentrations in eastern Canadian estuarine and coastal sediments. The results demonstrate that Li normalization may have a universal application to silicate sediments: it is superior to Al for the normalization of the metal data from sediments derived mainly from the glacial erosion of crystalline rocks, and equal or superior to Al for those derived from non-crystalline rocks. Normalization of the natural trace metal variability with Li also provides a procedure to identify and estimate relative anthropogenic trace metal inputs to estuarine and coastal sediments.

Partitioning and enrichment of trace metals in a sediment core from Framvaren, South Norway

Extremely high concentrations of Cd, Cu, Pb and Zn were recorded in the bottom sediments of the deep basin of Framvaren. The concentrations are comparable with those found in euxinic mid-Cretaceous black shales. The non-detrital phase (HOAc-extraction) constituted an average of 93, 25, 77 and 89% for Cd, Cu, Pb and Zn, respectively, of the total metal concentrations in the upper sediment. The most plausible explanation for the enrichment of metals is metal sulphide precipitation in the super-anoxic water (maximum 8 mmol l−1 total H2S). Metals could also be transferred to the sediments by sinking of organic matter (plankton and bacteria) produced in the euphotic zone. The variation in the concentrations of the non-detrital metal fraction reflects different solubility products of metal sulphide phases and organic matter associations.

Recent sedimentation events at the head of Saguenay Fjord, Canada

Unbioturbated marine sediments containing a record of high river discharge events occur at the head ofSaguenay Fjord, near Saint Fulgence, eastern Canada. Preservation of allochthonous benthonic foraminifera, recognition of occasional rapid sedimentation events associated with the spring runoff of the Saguenay River, and the unmixed character of the sediment can be used in conjunction with several dating techniques to obtain a temporal resolution of paleoriverine events on a time scale of months to years.The geologic and geochemical record of the upper 150 cm of sediment reflects (1) the anoxic character of the benthic environment, resulting from the high flux of terrigeneous material to the bottom; (2) the transport and deposition of landslide-derived sediment into the head of the fjord over several years; (3) an indication of the nature and timing of dissolution processes that have altered or totally eliminated the allochthonous calcareous microfossil assemblage from the recycled sediment; and (4) a cyclic depositional pattern that may be useful in reconstructing pateoclimatologic trends that have influenced annual river discharge of this drainage system over the past millennium.

Heavy metal contamination of a Greenland fjord system by mine wastes

Since 1973, about 500,000 tons/yr of metal-rich particulate tailings from a lead/zinc flotation mill have been discharged through a submarine outfall into a two fjord system on the west coast of Greenland. Differential solubilization of particulate metals by seawater, seasonal water mixing, and sill exchange tailings dispersal processes have resulted in high, but seasonally variable Zn, Cd, and Pb contamination of the water, and suspended particulate matter (SPM).Chemical partition of the SPM shows that most (85-99 percent) of the Pb, but relatively low proportions of Zn (14-26 percent) and Cd (10–20 percent) are weakly bound to the SPM. Such particulate metal characteristics allow the real time effects of tailings discharges and dispersal on the system to be traced even in the sediments where tailings accumulation is very slow (〈0.1 cm/yr).Fjord seaweeds and blue mussels also contain varying amounts of Zn, Pb, and Cd depending on the metal and their location relative to the tailings outfall and apparently responded almost instantly to the metal contamination, as did the water and SPM. High Pb concentrations in the fjord mussels most likely derive from the preferential uptake of available particulate Pb, whereas the seaweeds appear to derive most of their heavy metal concentrations from the dissolved phase. The evidence from this and other sites as well as from experimental work, indicates that any discharge of Pb-bearing particles into the marine environment either directly as mine wastes or indirectly as from natural runoff from current and former lead mining sites results in immediate lead contamination of the in situ mussel population.

Teflon bomb decomposition of silicate materials in a microwave oven

Abstract A method is described for the decomposition of silicate materials in 20-tal Tefion- TFE bombs by using a domestic microwave oven. A domestic pressure cooker was used as a precautionary device to contain acid fumes. Total decomposition of the reference materials, marine sediment MESS-1 and granite G-2, was achieved in 60 s with a mixture of hydrofluoric acid and aqua regia. By using flame or graphite-furnace atomic absorption spectrometry, recoveries greater than 97% were obtained for aluminium, chromium and zinc and greater than 93% for silicon in the samples and for silicon in a pure quartz rod.

Trace Metals in Suspended Particulate Matter and in Sediment Trap Material from a Permanently Anoxic Fjord- Framvaren, South Norway

Geochemical studies of the trace metal concentrations in suspended particulate matter (SPM) and sediment trap material from a permanently anoxic fjord, Framvaren, South Norway in 1989 and 1993 indicate that extremely high concentrations of zinc (max = 183920 mg/kg), copper (max = 4130 mg/kg), lead (max = 2752 mg/kg), and cadmium (max= 8.1 mg/kg) sometimes (1993) occur in the SPM collected in the anoxic water layer. The highest concentrations of Zn occur just below the redoxcline at 22 m water depth (in 1993), and copper, lead and cadmium have maximum concentrations between 30 and 80 m depth, where the amount of total SPM is at a minimum (about 0.3 mg/L). On a mass per volume (μg/L) basis, the maximum concentrations of Cd, Cu and Fe occur at the interface (21m) and those of Zn occur just below the redoxcline (22 m depth). The SPM and sediment trap data suggest that the metals are precipitated as sulfide minerals in the anoxic water. The presence of particulate sulfides was confirmed by SEM studies that show the occurrence of discrete metal (Cu, Fe, Pb, and Zn) sulfide particles in size from 10–20 μm as well as framboidal pyrites (1–5 μm in size). Higher levels of metal sulfides at intermediate depths rather than in the deep water of Framvaren (> 100 m), may be due to input of trace metals by water exchange over the sill in the upper part of the water column. In the deep water, less metal sulfide precipitation takes place due to depletion of trace metals, and the dilution of particulate metal concentrations by organic matter and by the chemogenic formation of calcite.

Arsenic and other Trace Metals in Sediments from the Kara Sea and the Ob and Yenisey Estuaries, Russia

Major (Al and Fe), minor (Mn) andtrace (As, Cd, Co, Cr, Cu, Hg, Li, Mo, Ni, Pb, Sb, Vand Zn) metals along with material of grain size<63 μm, TOC and TN have been determined insediment grab and core samples from the Kara Sea, andthe Ob and Yenisey estuaries, Russia. Surprisingly,the levels of trace metals, with the exception of As,were much lower than was anticipated from speculativereports of extensive contamination in the Arcticmarine areas adjacent to the Siberian coastline ofRussia. Lithium normalization indicates that theabundance and distribution of the metals, with theexception of As and Mo, are controlled by theaccumulation of their fine grained aluminosilicatehost minerals at sites determined by hydrodynamicconditions in the Kara Sea and in the estuaries. Metallevels in the Kara Sea and the Ob and Yeniseyestuaries, except for some anomalous As, Cu and Nivalues, are close to natural baseline levels of otherEurasian Arctic shelf sediments. High levels of As,however, occur in surface and subsurface sediments.The accumulation of As, as well as Mo, can beattributed to the post-depositional diagenetic effectsof Fe-Mn cycling both at and near the sediment waterinterface. Subsurface As and Fe maxima and minimasuggest alternating oxic and anoxic water conditionsduring post-glacial rises in sea level. In contrast tothe results from the adjacent Pechora Sea, in the KaraSea there is no correlation between the levels of Asand radionuclides in the sediments.

Depositional Processes in an Anoxic, High Sedimentation Regime in the Saguenay Fjord

The sediment dynamics of north temperate estuaries are seasonally modulated by factors such as ice cover, wind speed, and by the magnitude of the spring freshet. Anomalous events such as landslides, storms or consecutive years of high rainfall are also responsible for significant variations in annual sediment transport and deposition rates in coastal marine environments. Bioturbation of sediments deposited in these environments usually obscures much of the sedimentary and paleontologic record, however large amounts of organic detritus can lead to low O2 concentrations in or above sediments, causing reduced benthic activity, and unconformities may be preserved. The head of Saguenay Fjord in Eastern Canada has been identified as an area where detrital organic input to sediments is comparatively high.