Lars-Göran Danielsson

Trace metal determinations in estuarine waters by electrothermal atomic absorption spectrometry after extraction of dithiocarbamate complexes into freon

Cadmium, copper, iron, lead, nickel and zinc are determined. The dithiocarbamate complexes of the metals are extracted into Freon-TF and back-extracted into dilute nitric acid solution. Portions of the back-extracts are injected into a graphite furnace. The method gives complete separation from the matrix irrespective of salinity. It is therefore useful throughout the full salinity range of an estuary, 0–35‰.The effect of high iron concentrations on the extraction is eliminated by using a mixed acetate buffercomplexing agent solution.

Cadmium, copper, iron, nickel and zinc in the north-east Atlantic Ocean

Abstract The concentrations of cadmium, copper, iron, nickel and zinc have been determined on 105 water samples from the north-east Atlantic Ocean. Three rather different areas were sampled in this investigation. The first area is the Norwegian Sea, the birthplace for North Atlantic Deep Water (NADW), bordering the Arctic. Second, the relatively shallow Iceland-Faroe Ridge area where the newly formed deep water spills over into the northeast Atlantic. The third area sampled is the north-east Atlantic, further south, with less pronounced seasonal variations in temperature and light conditions. In the Norwegian Sea no surface depletion was found for cadmium, copper, nickel or zinc. The mean concentrations were (for unfiltered samples): Cd, 0.20 nM (22 ng l −1 ); Cu, 1.4 nM (90 ng l −1 ); Ni, 3.5 nM (200 ng l −1 ); and Zn, 1.5 nM (130 ng l −1 ). For iron the concentration in the surface water was 4.4 nM (250 ng l −1 ), with a slight increase towards the bottom. In the warm surface waters of the north-east Atlantic a depletion of cadmium and nickel was found for the surface waters that could be correlated to a depletion of nutrients. For copper and zinc the slight depletion found could not be correlated with any of the nutrients. In the deep waters of the north-east Atlantic, higher concentrations of cadmium, copper, nickel and zinc were found than at similar depths in the Norwegian sea. For iron, on the other hand, the concentrations were higher in the Norwegian Sea.

Cadmium, cobalt, copper, iron, lead, nickel and zinc in Indian Ocean water

Abstract Results of trace-metal analyses of water samples obtained during a cruise with the Soviet R.V. “Akademik Kurchatov” in the Indian Ocean are presented. The determinations were performed on board with atomic absorption spectrophotometry after a two-stage dithiocarbamate—Freon extraction procedure. Trace-metal concentrations found are in the same range as those found recently for similar open-ocean areas by other workers. The values for lead and zinc are probably high due to contamination. Vertical profiles indicate biogenic processes as controlling factors for the increase of cadmium, copper and nickel concentrations with depth. Iron shows an irregular depth distribution as a result of large random variations in concentration.

Trace metals in the Göta river estuary

Abstract The concentrations of the trace metals Cd, Cu, Fe, Ni, Pb and Zn in the Gota River estuary have been investigated. The following metal fractions have been determined: acid-leachable, dissolved, labile and particulate. The estuary represents a salt wedge type estuary and is situated in a densely populated region of Sweden. The metal concentrations found for the dissolved fraction is in the range of what can be considered as background levels for freshwater. It is difficult to evaluate any estuarine processes other than conservative mixing for Cd, Cu, Ni and Zn. The dissolved levels in the freshwater end member are Cd, 9–25 ngl −1 ; Cu, 1·1–1·4 μgl −1 ; Fe, 20–75 μg l −1 : Ni, 0·7–0·9 μg l −1 : Pb 0·09–0·2 μg l −1 ; and Zn, 6–7 μg l −1 : The results from the acid-leachable fraction show that at high suspended load the particles sediment in the river mouth. The trace metal levels in this fraction are subject to large variations.

Chemical investigations of Atlantis II and discovery brines in the Red Sea

Abstract Analytical data for the Atlantis II and Discovery deeps in the Red Sea are given. The data were collected in March and June 1976 during the 22nd cruise of R/V Akademik Kurchatov in the Indian Ocean. On board analyses were performed of density, chlorinity, Mg, Ca, Sr and trace elements. The salinity, calculated from the density, is related to the chlorinity by S = 1.67 Cl + 4.02. The Ca-salinity relation is linear for both deeps showing that intermediate waters are formed by mixing of the brines with Red Sea water (RSDW). The hot brine (62°C) in the Atlantis II deep contains approx. 80 mg/kg of Fe and Mn while the warm brine (45°C) in the Discovery deep has a very low concentration of Fe and approx. 50 mg/kg of Mn. Mixing of RSDW containing 2 ml/l of oxygen with the anoxic deep brines causes precipitation of hydrous Mn(IV) and Fe(III) hydroxides. These two processes occur at different depths in the two deeps due to the formation of the warm (48–49°) intermediate brine in the Atlantis II deep. The oxidation-hydrolysis reactions proposed are supported by alkalinity-depth profiles and measurements of pH. These reactions also explain most of the trace element distributions and the composition of the SiO 2 -Fe(III) hydroxide slurry recovered by some water samplers in the Atlantis II deep.

Trace Metals in the Arctic Ocean

Results from trace metal determinations on samples from a station in the Eastern Arctic Ocean are presented. Levels observed in subsurface water are Cd, 0.14–0.20 nM, Cu, 1.9–2.3 nM, Ni, 3.5–4.1 nM and for Zn, 0.86–3.9 nM. For these elements the surface depletion-bottom enrichment is weakly developed compared to that normally found in ocean waters. For iron, low levels were found in directly extracted samples (1.2–9.9 nM) while much higher levels (6.8–<63 nM) were found after storage under acid conditions.

Computerized potentiometric stripping analysis for the determination of cadmium, lead, copper and zinc in biological materials

Abstract Two different types of tinned mussels and a bovine liver reference sample have been analyzed for Zn, Cd, Pb and Cu by means of computerized potentiometric stripping analysis and atomic absorption spectrometry. The samples were digested by two different procedures, one employing nitric acid only and the other employing nitric and perchloric acids. It is shown that computerized stripping analysis can be used in samples containing high concentrations of electroactive organic nitro compounds, without sample deoxygenation.

Lead in the North Sea and the north east Atlantic Ocean

Abstract Lead has been determined in 105 water samples from the north east Atlantic and from the North Sea. Rigorous precautions were applied to avoid contamination during sampling and analysis. Two different analytical methods were used: ASV and AAS. Determinations with ASV were carried out on board, directly after sampling. After two months storage, acidified samples were analysed by AAS after freon dithiocarbamate extraction and nitric acid back extraction. Particulate lead was determined by AAS after an acid digestion. The profiles of lead concentration versus depth show around 160 pM at the surface and around 20 pM at the bottom, both in the Atlantic and in the Norwegian Sea. The shapes of the profiles are different, however, depending on the hydrography of the area sampled. The profiles from the north east Atlantic coincide with a recently published profile from the north west Atlantic. Moreover, these profiles have lead concentrations about a factor of three higher than those in the Pacific. Considering the high lead input to the North Sea, the lead concentrations found there are remarkably low, probably because of scavenging effects in estuaries leading to a short residence time in the water column. The dominant lead input in offshore regions is from the atmosphere. The highest lead levels are found in the northern North Sea, around 300 pM in surface water. In the Atlantic, particulate lead is a minor part of the total lead whereas in the North Sea the particulate fraction is larger, up to 40%.

Intercomparison of different methods for the determination of trace metals in seawater

Abstract During a cruise on the North Sea and the North East Atlantic, about 90 samples were obtained from various depths. Concentrations of cadmium, copper, lead, nickel and zinc were determined by atomic absorption spectroscopy after separation/concentration using two different extraction methods. One, using APDC and MIBK, was applied directly on board while the other, using a mixture of dithiocarbamates and freon, was applied after storage under acid conditions. About half of the samples were also analysed for cadmium, copper and lead using ASV. The results of these determinations are intercompared. Consistent results were obtained for cadmium with the two extraction methods and for lead with the freon extraction method and ASV. In the other cases discrepancies were found.

Determination of Cadmium and Lead in Sea Water after Extraction Using Electrothermal Atomisation. Minimisation of Interferences from Co-Extracted Sea Salts

Abstract Interferences from small amounts of sea salt in the determination of cadmium and lead were investigated. Test samples were made to mimic solutions obtained after extraction of sea water for trace metal analysis. Sea salt concentrations in the range 0–400 mg/l were investigated. Background absorption from this salt was high but easily minimised through the addition of nitric acid (2 % v/v). Sensitivity reductions due to the salt were considerable and varied from one graphite tube to the other. This problem was overcome by the addition of 1000 mg lanthanum per litre of sample. The positive effect of the lanthanum matrix modification is thought to be due to a change of the graphite tube surface.