Elevated Levels Of Zn Research Articles

Porites corals as recorders of mining and environmental impacts: Misima Island, Papua New Guinea

In 1989 open-cut gold mining commenced on Misima Island in Papua New Guinea (PNG). Open-cut mining by its nature causes a significant increase in sedimentation via the exposure of soils to the erosive forces of rain and runoff. This increased sedimentation affected the nearby fringing coral reef to varying degrees, ranging from coral mortality (smothering) to relatively minor short-term impacts. The sediment associated with the mining operation consists of weathered quartz feldspar, greenstone, and schist. These rocks have distinct chemical characteristics (rare earth element patterns and high abundances of manganese, zinc, and lead) and are entering the near-shore environment in considerably higher than normal concentrations. Using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), we analyzed eight colonies (two from high sedimentation, two transitional, two minor, and two unaffected control sites) for Y, La, Ce, Mn, Zn, and Pb. All sites show low steady background levels prior to the commencement of mining in 1988. Subsequently, all sites apart from the control show dramatic increases of Y, La, and Ce associated with the increased sedimentation as well as rapid decreases following the cessation of mining. The elements Zn and Pb exhibit a different behavior, increasing in concentration after 1989 when ore processing began and one year after initial mining operations. Elevated levels of Zn and Pb in corals has continued well after the cessation of mining, indicating ongoing transport into the reef of these metals via sulfate-rich waters. Rare earth element (REE) abundance patterns measured in two corals show significant differences compared to Coral Sea seawater. The corals display enrichments in the light and middle REEs while the heavy REEs are depleted relative to the seawater pattern. This suggests that the nearshore seawater REE pattern is dominated by island sedimentation. Trace element abundances of Misima Island corals clearly record the dramatic changes in the environmental conditions at this site and provide a basis for identifying anthropogenic influences on corals reefs.

Contamination of the Biological Compartment in the Seine Estuary by Cd, Cu, Pb, and Zn

A study of contamination of the biological compartment of the Seine estuary was carried out by measuring the concentrations of cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) in 29 estuarine and marine species belonging to 6 phyla. Species came from three main biological zones of the estuary: the Seine channel (copepods, mysids, shrimps, and fish), the intertidal mudflats (Macoma balthica community), and the subtidal mudflats (Abra alba community). Two fish species, the bass (Dicentrarchus labrax) and the flounder (Platichthys flesus), were also selected for analyses. A comparison of metal concentrations in estuarine species of the Seine with those found in the same species collected on contaminated and non-contaminated sites showed a contamination of the estuary by Cu, Zn, and Pb. For Cd, the contamination is mainly observed in bivalves, although the concentrations observed were low and less than 2 μg g−1 d.w. High concentrations of Cu were found in copepods, shrimps, and fish. Pb contamination was mainly found in species living in the Seine channel where the copepodEurytemora affinis shows an average concentration of 22 μg g−1 d.w. High concentrations of Pb (>10 μg g−1 d.w.) were found in deposit-feeders benthic invertebrates. Elevated levels of Zn were seen in all species collected in the Seine estuary, including fish and in particular small flounder. The concentrations of Cd, Cu, Pb, and Zn found in edible estuarine species (shrimp and fish) were in the same order of magnitude than those found in fish and shrimps fished along the French coast.

Distribution and movement of sludge-derived trace metals in selected Nigerian soils.

Use of metal-rich sewage sludge as soil fertilizer may result in trace- metal contamination of soils. This study was conducted to evaluate the effects of long-term sludge application on trace-metal (Zn, Cu, Pb, and Ni) distribution and potential bioavailability in Nigerian soils under a tropical wet-dry climate. Total metal analyses, sequential chemical fractionation, and DTPA extractions were carried out on samples of control and sludge-amended pedons in Nigeria (a Rhodic Kandiustult and two Rhodic Kandiustalfs from Nigeria, respectively). The sewage sludge applied to the soils contained higher levels of Zn and Cu than Pb and Ni. The control pedon contained low levels of all four metals. Soil enrichment factors (EF) were calculated for each metal in the sludge-amended pedons. Compared with the control soil, the sludge-amended pedons showed elevated levels of Zn and Cu, reflecting the trace-metal composition of the sewage sludge. Zinc and Cu in the sludge-amended soils were strongly enriched at all depths in the profile, indicating that they had moved below the zone of sludge application. The sequential extraction and DTPA analyses indicated that the sludge-amended soils contained more readily extractable and bioavailable metal ions than the unamended soil.

Interaction of Zn2+ with the donor side of Photosystem II

The inhibitory effect of Zn(2+) on photosynthetic electron transport was investigated in native and CaCl2-treated (depleted in extrinsic polypeptides) Photosystem II (PS II) submembrane preparations. Inhibition of 2,6-dichlorophenolindophenol photoreduction by Zn(2+) was much stronger in protein-depleted preparations in comparison to the native form. It was found that Ca(2+) significantly reduced the inhibition in the native PS II preparations, as did Mn(2+) in a combination with H2O2 in the protein-depleted counterparts. No other tested monovalent or divalent cations could replace Ca(2+) or Mn(2+) in the respective experiments. Diphenylcarbazide could partially relieve (40-45%) the inhibition in both types of preparations. The above indicates the presence of an active Zn(2+) inhibitory site on the donor side of PS II. However, neither Ca(2+) nor Mn(2+) could completely prevent inhibition by high concentrations of Zn(2+) (>1 mM). We propose that elevated levels of Zn(2+) strongly perturb the conformation of the PS II core complex and might also affect the acceptor side of the photosystem.

Zinc‐induced vacuolation in root meristematic cells of Festuca rubra L.

Abstract. The effect of Zn on vacuole development in root meristematic cells was examined in three cultivars of Festuca rubra: a Zn‐tolerant cultivar (Merlin), a salt‐tolerant cultivar (Hawk) and a non‐tolerant cultivar (S.59) in order to determine whether or not vacuole development was related to Zn tolerance. Treatment with Zn greatly increased the percentage of cells in the apical meristem which were vacuolated in all three cultivars (7.01‐fold increase in Merlin, 3.61‐fold increase in Hawk and 5.39‐fold increase in S.59 over the range 0–0.5 μg Zn cm−3). Morphometric analyses on electromicrographs indicated that the percentage total vacuolar volume fraction of meristematic tissue was also increased by Zn treatment. Most of this increase was due to an increase in a particular component of the vacuole which was 0.2–0.5 μm in diameter, spherical or ovoid in outline and possessed a distinct amorphous electron dense matrix (Type A intravacuolar body). X‐ray microanalysis revealed that this matrix was rich in calcium and phosphorus in control plants. In Zn‐treated roots, elevated levels of Zn were found in the matrix in Merlin and Hawk, but not in S.59. In addition, intravacuolar membranous whorls or myelin bodies were more highly organized in Zn‐treated Merlin and Hawk but not S.59. Elevated Zn levels were not found in any other vacuolar component nor in nuclei, nucleoli, cell walls or ground cytoplasm. Control roots of Merlin possessed a greater type A vacuolar volume fraction than either Hawk or S.59 which may confer a greater capacity to compartmentalize Zn at the onset of exposure to toxic metals than the other cultivars. Predictably, the EM procedures resulted in loss of Zn from the roots to the fixative and dehydrating solutions. However, the rate of loss was the same (approximately 75–80%) regardless of cultivar. These findings are discussed in relation to their possible role in the mechanisms of Zn tolerance in these cultivars.

The involvement of epiphytic bacteria in zinc concentration by the red alga Gracilaria sordida

Atomic Absorption Spectrophotometry (AAS), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS) were used to study the contribution of epiphytic bacteria to zinc (Zn) concentration by the red alga Gracilaria sordida W. A. Nelson. AAS showed that high concentrations of Zn became associated with G. sordida following exposure to elevated Zn levels in laboratory experiments. Changes in the form of epiphytic bacterial extracellular polymers on exposure to Zn were observed by SEM. Both the number of bacterial cells and the quantity of the associated extracellular polymers decreased with increasing ambient Zn concentration. EDS revealed that Zn was localized in the extracellular polymers surrounding the bacteria and in the cell walls and intercellular spaces of the alga.

A historical study of mineral elements in forest plants from South Norway

Herbarium plants were used as a material to study possible long-term changes in mineral elements of forest plants. Plants from South Norway collected in the period 1870 to 1930 were compared to plants collected in 1982. Relative to mineral contents in plants from 1870 to 1930, the 1982 material showed elevated levels of Zn, Cd, Rb, K, Mn and Ti and decreased levels of Sr, B, Ca and Mo in some of the plant species analysed. Most of these differences may be explained by changes in the environmental conditions, due to differences in chemical composition of precipitation, accelerated soil acidification and subsequent increasing mineral weathering. Consequently analysis of herbarium plants seems to provide valuable information about preindustrial levels of mineral elements and seems to detect changes in mineral elements brought about by recent anthropogenic activity.

Effect of Elevated Levels of Zinc on Growth of Synechococcus 6301

Summary Synechococcus 6301 cells through repeated sub-culturing when adapted to mildly elevated levels of Zn 2+ (6 μM, applied as ZnSO 4 ) induced a general elongation in cell size. Measurements of growth parameters indicated that in Zn 2+ adapted cells the total chlorophyll, phycocyanin and protein contents declined when expressed on per ml −1 culture basis. However, on per cell basis except phycocyanin, chlorophyll and protein contents were higher in Zn 2+ adapted cells than in control. A significant increase in dry mass of the alga was also noticed in treated samples over control. Zinc adaptation, however, did not significantly alter the photosystem II mediated electron transport or CO 2 fixation activities of the alga.

Metal uptake in plants from a birch forest area near a copper smelter in Norway

Uptake of Ca, Mg, K, Mn, Fe, Al, Rb, Ph, Cu, Zn, and Cd in vascular plants from a birch forest area near a Cu smelter in northern Norway was investigated. The primary objective was to study metal uptake in plants growing in a strong local acidification gradient. Decreased levels of Mn, Mg, and Ca found in Betula pubescens, Vaccinum myrtillus, and Deschampsia flexuosa near the smelter corresponded to a decrease in base saturation of the soil. This suggests that appreciable soil acidification has taken place. The level of Rb in Vaccinum myrtillus and Sorbus aucuparia increased significantly towards the smelter, probably due to the higher soil acidity. Elevated levels of Cu, Zn, Ph, and Cd in surface soil were found with values up to 2500 mg kg−1 Cu within 1 km from the smelter. These concentrations decreased significantly with distance, but metal contamination was detectable up to 27 km from the smelter along the prevailing wind direction. A corresponding decrease was detected for Cu in the four plant species analyzed. Elevated levels of Zn, Ph, Fe, and Al were found in some, but not all, species.

PIXE Analysis in Different Stages of Psoriatic Skin

Elemental distribution in psoriatic skin varies with the functional state of the keratinocytes, e.g., electrolytes influence cell metabolism and cell proliferation, and trace elements play a crucial role in a great number of enzymes. Elemental distribution in pinpoint lesions, old plaques, and uninvolved skin of 5 psoriatic patients and 4 healthy controls was studied by means of PIXE (proton-induced x-ray emission) analysis. This technique allows the simultaneous detection of elements with an atomic number greater than or equal to 14 along the epidermis and dermis in freeze-dried skin biopsies. Trace elements such as Fe, Cu, and Zn were determined down to a level of 1 ppm. In comparison with uninvolved skin, concentrations of P and K were elevated in psoriatic epidermis. In addition, increased levels of K were correlated with the stage of the psoriatic lesion. Zinc concentrations were significantly elevated in pinpoint lesions. The Zn concentration profiles within the epidermis and upper dermis showed high correlation to the P concentration profiles. Iron levels were decreased in old psoriatic plaques, whereas Cu concentrations varied considerably. In comparison to the controls, Cl concentrations were markedly decreased in the dermis of involved and uninvolved psoriatic skin, whereas epidermal Cl levels were unaffected. As high K levels prevent the Ca-induced differentiation of keratinocytes, high K levels may be the cause of the high cell differentiation in psoriatic skin. Elevated DNA- and RNA-polymerases might be the cause of elevated Zn levels in pinpoint lesions.

Zonation of chalcophile elements about the howard's pass (XY) Zn-Pb deposit, Selwyn Basin, Yukon

ABSTRACT Goodfellow, W.D., Jonasson, I.R. and Morganti, J.M., 1983. Zonation of chalcophile elements about the Howard's Pass (XY) Zn-Pb deposit, Selwyn Basin, Yukon. In: G.R. Parslow (Editor), Geochemical Exploration 1982. J. Geochem. Explor., 19: 503–542. The Selwyn Basin comprises those rocks of Paleozoic age that were deposited in a fault-controlled epicratonic basin or aulacogen bounded by the Mackenzie Platform on the east and north, and the Cassiar Platform to the west. Boundaries between sedimentary facies within the Selwyn Basin during Ordovician to Middle Silurian time were parallel to and symetrically disposed about the long axis of that basin, consisting of chert in the central and deeper zone and shales in the flanking zones. Conodont dates indicate that the Howard's Pass (XY) Zn-Pb deposit formed during Llandoverian time in a local third-order basin within the shale facies. Various geological features such as abrupt facies changes, local thickening and slumping of sedimentary units suggest that growth faults played an important role in basin development as well as serving as conduits for the discharge of ore-forming fluids. The only sulphides recognized to date at the XY deposit are sphalerite, galena, chalcopyrite and pyrite. Sphalerite and galena can occur as concordant, fine laminations, or remobilized into sedimentary dewatering structures, or transposed and remobilized into a tectonic (slaty) cleavage. Pyrite most commonly forms diagenetic microframboids which postdate the laminated sulphides but predate the sphalerite and galena emplaced in dewatering structures. Within the main ore-bearing unit, i.e. the Active Member, the Pb/(Pb+Zn) ratio decreases stratigraphically upwards and laterally towards the margins of the deposit. This zonation accompanies a change in host-rock composition from cherty limestone at the base to carbonaceous chert towards the top of the Active Member. In addition to Zn and Pb, the other chalcophile elements concentrated in the Active Member are Cd and Hg, both of which are bound isomorphously in sphalerite. Both ore-forming and ore-associated elements are zoned stratigraphically and laterally in the host rocks of the XY deposit. The footwall carbonaceous mudstones are enriched in Ni, Cu, Co, Mo, As, Sb, Zn, Cd, Hg and Pb relative to rocks of similar age and composition located remote from mineralization. Ni, Cu, Co, Mo, As and Sb now reside in diagenetic pyrite but in whole rock chemical analyses show a strong positive correlation with organic C. On the other hand, Zn, Cd, Hg and Pb are bound in sphalerite or galena. By comparison, the overlying phosphatic chert is enriched in Ni and Cu only, both of which correlate positively with organic C. The zonation of these elements reflects a decrease in pyrite content in the rocks and also a decrease in trace-element contents of pyrite itself away from the XY deposit. On the basis of extremely low S/C ratios, the low pyrite content outside the XY deposit is thought to be due to a lack of sufficient Fe2+ to fix S2- generated by bacterial reduction during diagenesis. The higher content of Fe near the XY deposit probably reflects Fe debouched onto the seafloor during hydrothermal activity. The increased trace-element content of pyrite in rocks hosting the XY deposit is due most likely to elevated levels of these elements accumulated by dead organic matter from ore-forming fluids during sedimentation. A period of Devonian hydrothermal activity in the Howard's Pass area can be recognized by elevated levels of Zn, Hg, Sb, Ag, As, Mo and Ni in highly carbonaceous and calcareous rocks. The spatial association of these Devonian metalliferous mudstones with the underlying XY deposit suggests that structures which served as conduits for the discharge of ore-forming fluids during the Lower Silurian were reactivated in Devonian time.

Tolerance and Resistance to Cadmium in White Suckers (Catostomus commersoni) Previously Exposed to Cadmium, Mercury, Zinc, or Selenium

White suckers' (Catostomus commersoni) tolerance of and resistance to Cd is increased as a consequence of previous metal exposure. The order of metal toxicity to white suckers was Hg > Cd > Zn >> Se. Toxicity curves clearly showed that white suckers exposed to sufficiently elevated Cd, Hg, or Zn levels subsequently survived longer than control suckers in Cd toxicity tests. The 96-h Cd LC50 increased by 61 or 127% following 1 wk exposure to.0.40 or 0.72, respectively, of the 96-h Cd LC50 (1.11 mg Cd/L) for control suckers. The 96-h Cd LC50 also increased by 260% following 1 wk exposure to 0.32 of the 96-h Hg LC50 (0.687 mg Hg/L). The 12- and 24-h Cd LC50 values were increased, but the 48-, 72-, and 96-h values were not, following 1 wk exposure to elevated Zn levels. Exposure to Se prior to toxicity testing had little or no effect on Cd toxicity. Mechanisms which might be responsible for the decreased Cd toxicity include decreased uptake, increased excretion, redistribution of metals to less-sensitive target sites, and/or induced synthesis of metallothionein. Possible consequences of increased tolerance to metals include compensatory adjustments which result in poor recruitment into the population, accumulation of potentially toxic metals, and increased survival in metal-impacted areas.Key words: tolerance, resistance, acclimation, cadmium, mercury, zinc, selenium, white sucker, Catostomus commersoni, toxicity

Zinc tolerance in strains of the blue-green algaAnacystis nidulans

Mutants of Anacystis nidulans tolerant to high levels of zinc were obtained by repeated subculturing at concentrations of the metal sufficient to cause a marked reduction in growth rate. The level of Zn just permitting detectable growth was raised from 1·45 to 16·5 mg Zn 1-1 after 75 subcultures. Two strains tolerating elevated levels of Zn were chosen for comparison with the wild-type. Zinc toxicity to all three strains was reduced by increases in Ca, Mn and P, but the tolerant strains differed from the wild-type in their response to four other variables, Na, Mg, Fe III and pH. In the case of pH, the responses of wild-type and tolerant strains were contrasting: a rise in pH from 6·5 to 8·0 led to decreased Zn toxicity to the former and increased toxicity to the latter. Increased levels of zinc led to increased formation of filaments by all strains. Although the tolerant strains required more zinc to bring about an equivalent toxic and morphological response, there was no evidence from uptake experiments ...

Investigations of the potential of bivalve molluscs as indicators of heavy metal levels in tropical marine waters

The relationships between concentrations of the heavy metals Pb, Cd, Cu, Zn, Co, Ni, and Ag in nine bivalve molluscs (Arca ventricosa, Chama isotoma: Lithophaga teres. Pinctada margiritifera, Pycnodonte hyotis. Spondylus ducalis. Modiolus auriculatus, Trichomya hirsuta, Ustularca renuta) and their environment were studied. The variation in heavy metal accumulation in these field samples and the effects on metal levels and condition of the organisms after relocating for 2 months four of these species (T. hirsuta, M. auriculatus, S. ducalis and C. isotoma), were also studied. The relocated animals maintained or improved condition as judged by the condition index (i.e. ratio of tissue wet weight to shell diameter or weight) during the expefimental period. Levels of Pb and Cu in relocated T. hirsuta varied directly with environmental levels but elevated levels of Zn in the environment were not indicated by this organism. Accumulation of Pb and Cd by T. hirsuta was linear with time and increased in direct proportion to the external concentration of these metals. No loss of either metal was detected after 12 days in 'normal' seawater. The results indicate that T. hirsuta would be a suitable organism for detecting increased levels of heavy metals, except Zn, in the environment.

Manganese, copper and zinc concentrations in human skin lesions

Trace element analysis by neutron activation was performed on biopsies from normal skin, benign and malignant lesions. Particular attention was focused on Cu, Zn and Mn contents since good “baseline” values are available for normal skin biopsies. The most important results were obtained for Cu and Mn where significant concentration differences were associated with malignancy or benignity. Average values of Mn in normal skin, in benign nevi and in malignant lesions were 0.1 ± 0.1, 1.1 ± 0.6 and 4.7 ± 1.9 μg/g (dry weight), respectively. For Zn our values for normal skin were substantially lower than those reported by others. For malignant biopsies, half the samples showed, elevated Zn levels while half showed depressed levels. Cu concentrations in five of six malignant samples averaged 308 μg/g compared to a value of 4.3 μg/g for normal skin.