Showing papers on "Trace metal published in 1988"

Zinc, chromium, vanadium and iron in the Mediterranean Sea

Abstract: Mediterranean surface waters contain elevated levels of zinc and chromium and slightly lower levels of vanadium compared to similar nutrient-depleted open ocean waters. A detailed mapping of surface concentrations in the Alboran Sea (immediately east of the Strait of Gibraltar) reveals that maximum total dissolvable concentrations of Zn (9.4 nmol kg −1 , Cr (3.9 nmol kg −1 ), V (35 nmol kg −1 ) and total Fe (53 nmol kg −1 ) occur in the core of the Atlantic inflow jet. These distributions imply that a portion of Mediterranean trace metal enrichment occurs during passage of surface water through the coastal region and into the Strait, as observed previously for Cu and Cd. Mass balance indicates that about half of the Mediterranean Zn enrichment, and most of the Cr enrichment, is due to sources within the basin itself. High concentrations of particulate Fe in the Alboran Sea suggest eolian input or recent sediment resuspension, but in general metal sources are difficult to identify and could be fluvial or anthropogenic as well as eolian and sedimentary. Chromium and V levels in Mediterranean deep water are similar to surface water concentrations near deep-water formation regions, but Zn is enriched in deep water, implying some vertical transport by biological cycling. A simple steady-state box model indicates that about 30% of the Zn transport is particulate and that the Zn: nutrient ration in sinking particulate matter is similar to that in open ocean particulates.

Entrainment of trace-metal-enriched Atlantic-shelf water in the inflow to the Mediterranean Sea

Abstract: Surface waters of the Mediterranean Sea have higher trace-metal concentrations than open Atlantic surface waters1. This observation could be explained by sources within the basin, but recent data from the Alboran Sea2 indicate that trace metals may already be enriched in Atlantic waters flowing into the Mediterranean through the Strait of Gibraltar. Here we present new data documenting the presence of trace-metal-enriched source waters west of the Strait, and present a mathematical analysis showing that Cu, Ni, Cd and Zn distributions in the Alboran Sea can be explained as linear mixtures of four well–defined sources: (1) Spanish coastal waters, (2) North Atlantic Central Water, (3) Atlantic surface water, and (4) Mediterranean Levantine Intermediate Water. In this analysis, salinity and trace metals are used for the first time to deconvolve mixing between water masses of different origins.

Evaluation of inductively coupled argon plasma mass spectrometry (ICP-MS) for simultaneous multi-element trace analysis in clinical chemistry

Abstract: The suitability of inductively coupled plasma mass spectrometry (ICP-MS) for the determination of trace amounts of inorganic elements in clinical samples has been investigated. Protein solutions, which were known to be free from biohazards, were obtained in sufficient amounts to allow the preparation of three pools of material of differing trace metal content. Freeze-dried portions were distributed to four different laboratories with established expertise in trace element analysis.The elements Mg, Al, Cr, Mn, Fe, Ni, Cu, Zn and Se as determined by ICP-MS showed reasonable agreement with the values obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES), simultaneous multi-element atomic absorption continuum source (SIMAAC) spectrometry and by established flame and graphite furnace atomic absorption spectrometry (FAAS and GFAAS) procedures.A commercial source of freeze-dried urine with assigned values for a range of trace elements was analysed by ICP-MS. Acceptable results were obtained for elements with mass numbers greater than 81 (e.g., Pb, Cd, Hg and Tl). However, with the exception of Co, results obtained for the first row transition elements, as well as for As and Se, were severely degraded by polyatomic interferences. Acid digests of dried bovine liver (NBS SRM 1577) were also analysed by ICP-MS and acceptable agreement with the certified values found for Mn, Fe, Cu, Co, Rb, Zn, Sr and Mo. Modification of the sample preparation procedure by precipitation of chloride prior to analysis by ICP-MS has been found to offer advantages for some elements.

Trace metal interactions with microbial biofilms in natural and engineered systems

Abstract: Trace metal adsorption and desorption are important processes in natural aquatic systems and in designed treatment systems. Adsorption of metals onto particulate matter and humic substances has been documented in fresh water and marine systems. Although biofilms coating surfaces are well documented, the chemical mechanisms concerning metal removal have not been investigated thoroughly. Biofilms consist predominantly of bacterial cells enmeshed in a network of negatively charged extracellular polymers. The biofilms are assumed to contain ferromanganese deposits which can play an important role in trace metal absorption. Microorganisms have developed resistance to metal toxicity, especially since the Industrial Revolution. Detoxification mechanisms include biomethylation, biosynthesis of intracellular traps, cellular efflux, synthesis of chelating agents, and surface precipitation. Mathematical models have been developed to describe various aspects of trace metal interaction with surfaces: (1) cellular growth, attachment, and polymer production; (2) metal binding to inorganic surfaces; (3) metal binding to cellular surfaces; and (4) biofilm model integrated with a metal-binding model.

Dissolved gallium in the open ocean

Abstract: Greater understanding of the distributions and biogeochemical cycling of trace metals in the oceans has recently been attained due largely to advances in analytical chemistry and in trace metal sampling. We present here the first oceanographically consistent distribution of dissolved gallium in the open ocean, with concentrations 1–2 orders of magnitude lower than those reported previously1–3. The distribution of dissolved gallium is complex, indicating multiple sources and removal by scavenging throughout the water column.

The Determination of trace metals in natural waters

Abstract: Spectrophotometric and fluorimetric methods Atomic-, mass-, X-ray-spectrometric methods, electronparamagnetic and luminescence methods Voltammetric methods Neutron activation analysis Measurement of pH in natural waters Electroanalytical measurement of trace metals complexation Trace metal complexation by inorganic ligands in sea water Adsorption of trade elements by suspended particulate matter in aquatic systems Physicochemical speciation of trace elements in oxygenated estuarine waters Chemical mechanisms operating in sea water.

Trace Metal Dynamics in a Seasonally Anoxic Lake

Abstract: Selected results are presented from a detailed 12-month study of trace metals in a seasonally anoxic lake. Dissolved concentrations of Fe, Mn, organic carbon, Cd, Cu, Pb, Zn, and pH were determined in the water column and the interstitial waters on 39 occasions. Trace metal concentrations remained low throughout the year in both water column and pore waters. There was evidence for some remobilization at the sediment-water interface but sediments deeper than 3 cm acted as a sink throughout the year. Variations in the water concentrations were largely associated with increased loading during periods of heavy rainfall. During the summer, concentrations of Cu and Zn in the waters overlying the sediments were enhanced by release from decomposing algal material. Similarly, enhanced concentrations of Cd, Cu, Pb, and Zn were observed during periods of much reduced mixing during ice-cover. Although there were large seasonal variations in the concentrations of dissolved and particulate Fe and Mn, there were no comparable changes in the concentrations of trace metals.

Aquatic insects as environmental monitors of trace metal contamination: Red River, New Mexico

Abstract: Discontinuous sampling of water for toxic chemicals is unreliable in lotic ecosystems or in systems subjected to sporadic discharges. Such sampling either fails to detect the contaminants or seriously underestimates their concentrations. This study explored the use of resident aquatic insects as biomonitors of trace metal contamination in a river subjected to episodic spills of Mo mill tailings. Aquatic insects at sites downstream from the mill accumulated more Mo and Cu than upstream insects. Due to a prolonged shutdown at the mine, no tailings spills were recorded during this study and Mo and Cu levels in water and bottom sediments declined to near background levels. However, concentrations of these metals in insects declined only slightly. This study indicates that aquatic insects are useful biomonitors of trace metal contamination in an intermittently impacted system. Reduction of elevated trace metal concentrations from the insects occurred at a slower rate than from the non-living components of the river ecosystem thereby facilitating detection of the spills.

Behaviour and Impact Assessment of Heavy Metals in Estuarine and Coastal Zones

Abstract: Metals are present in various compartments or reservoirs in the aquatic system. A simplified description is based on four abiotic and three biotic reservoirs (Fig. 1). As abiotic reservoirs, the deposited sediments, the interstitital water, the suspended matter and the surface water can be distinguished. Under reducing conditions the deposited sediments can provide the interstitital waters with high concentrations of nutrients and heavy metals, which may influence the composition of the surface waters through processes of diffusion, consolidation, erosion and bioturbation Open image in new window Fig. 1. Review of the role of micro-pollutants in an aquatic ecosystem (Salomons 1985). Apart from physical processes, biologically mediated reactions occur in the sediment, by which some metals are transformed in methylated species (Salomons and Forstner 1984). The contribution of the four abiotic reservoirs to the heavy metal burden of aquatic organisms depends on their bioavailability and their habitat. Filter feeders and planktonic organisms are exposed to dissolved and particulate heavy metals. The deposit feeders and meiofauna on the other hand ingest sedimentary particles and the associated pore waters as well as metals present in bacteria living in the sediment.

Forest clearcutting effects on trace metal concentrations: spatial patterns in soil solutions and streams

Abstract: Increased concentrations of solutes in drainage waters following forest clearcutting may affect downstream water quality. The objective of this study was to evaluate some of the processes regulating concentrations of trace metals and Fe in soil solutions and streamwater in a clearcut watershed by determining changes in metal release by soil horizon, stand vegetation and elevation. Commercial whole-tree harvesting of a watershed at the Hubbard Brook Experimental Forest, NH, U.S.A. resulted in increased loss of NO inf3 sup− from the study watershed. This N0 inf3 sup− loss resulted in acidification of soil solutions, which was associated with release of Mn and Zn from mineral soil to soil solutions and streamwater. Significant correlations of Pb and Fe with dissolved organic C (DOC) suggested that mobilization of these metals was linked to DOC transfer. However, there was little evidence of increased release of DOC, Fe, or Pb following the whole-tree harvest, except in a high elevation spruce-fir zone with shallow soils.

Trace metal levels in fish from Urola river (Spain) Anguillidae, Mugillidae and Salmonidae

Abstract: Heavy metals have been determined in tissues of freshwater fish ( Anguilla anguilla, Chelon labrosus and Salmo trutta fario ) from Urola River (Spain). Samples were wet digested and analysed by atomic absorption spectroscopy. Fish from the more polluted places show higher metal levels in gills. Iron concentration in trout gills seems to be related to surface absorption processes. High concentrations of copper and iron have been found in eel muscle in some of the sampling places.

Trace metals in squidIllex argentinus

Abstract: The determination of the cadmium, silver, lead, copper, zinc, manganese, iron and mercury levels is reported in edible and inedible tissues of the squid speciesIllex argentinus, caught in the region of the Continental Shelf of Argentina in 1986.

Correlation between some selected trace metal concentrations in six species of fish from the Arabian Sea

Abstract: The role of trace metals in marine ecosystems has been keenly investigated during recent years. It is known that abundance of essential trace metals regulates the metal content in the organisms by homeostatic control mechanisms, which when cease to function cause essential trace metals to act in an either acutely or chronically toxic manner. Therefore, a correlation study based on essential and non-essential trace metal concentrations is imperative for extending the existing knowledge of bioaccumulation of trace metals in marine organisms. An attempt has been made in the present investigation to bring out quantitative correlations between the concentrations of iron, copper, lead and zinc in the edible muscle tissue of six species of marine fish: Salmon (salmon sole); tuna (thunnus thynnus); pomfret silver (pampus argenteus); Pomfret black (formioniger); long tail tuna (thynnus tonggel) and Indian oil sardine (sardinella longiceps). These fish are abundantly available in Pakistan along the coastal line of the Arabian Sea and have great commercial value. The computational analysis on the trace metal correlation was conducted using an MSTAT statistical package.