Sorghum genotypic differences in tolerance to excess manganese

Manganese (Mn) toxicity can be a growth limiting constraint for many plants grown on acid soil. Plant species/genotypes tolerant to Mn could help overcome detrimental Mn toxicity effects on plants grown on high Mn soils. Thirty‐seven sorghum [Sorghum bicolor (L.) Moench] genotypes from a broad germplasm base were grown in solution culture (pH 4.5) with 0, 3.0, and 6.0 mM of added Mn above the basic solution concentration (18 μM) to determine genotypic differences in tolerance to excess Mn. Dry matter (DM) was used to evaluate 24‐day‐old plants (10 days in Mn treatments) for Mn toxicity responses. Wide variability among genotypes for differential DM was noted at 3.0 and 6.0 mM Mn. Sorghum generally tolerated high levels of Mn. Genotypes showing relatively high tolerance to excess Mn in solution were NB 9040, Wheatland, IS 7180, IS 7755, and IS 7809. Those genotypes showing relatively low tolerance to high Mn were ICA‐Nataima, Martin, IS 7173c (SC 283), IS 7321, IS 9187, IS 9785, and IS 9828. IS 7173c, an aluminum (Al)‐tolerant standard genotype, was sensitive to high Mn. Wide variability was noted among tissue culture generated lines derived from a common parent. Laboratory screening for tolerance to Mn toxicity was effective with sorghum, but results need to be verified in the field.     

Effect of Free Manganese Activity on Yield and Uptake of Micronutrient Cations by Barley and Oat grown in Chelator-buffered Nutrient Solution

The uptake of micronutrient cations in relation to varying activities of Mn²⁺ was studied for barley (Hordeum vulgare L. var. Thule) and oat (Avena sativa L. var. Biri) grown in chelator buffered nutrient solution. Free activities of Mn²⁺ were calculated by using the chemical speciation programme GEOCHEM-PC. Manganese deficient conditions induced elevated concentrations of Zn and Fe in shoots of both species. The corresponding antagonistic relationship between Mn and Cu could only be seen in barley. The observed antagonistic relationships were only valid as long as the plant growth was limited by Mn deficiency. The Mn concentration in both plant species increased significantly with increasing Mn²⁺ activity in the nutrient solution. The concentration of Mn in the shoots of oat was higher than for barley except under severe Mn deficiency where it was found equal for both species. Manganese was accumulated in the roots of barley at high Mn²⁺ activity. The different shoot concentrations of Mn between barley and oat are therefore attributed to the extent of Mn translocation from roots to shoots. Manganese deficiency induced a significant increase in the shoot to root ratio in both species.     

Bioavailability of Metals at a Southeastern Brazilian Coastal Area of High Environmental Concern Under Anthropic Influence: Evaluation Using Transplanted Bivalves (<Emphasis Type="Italic">Nodipecten nodosus</Emphasis>) and the DGT Technique

Metals are commonly determined in aquatic organisms, primarily using bivalves to provide important data on their bioavailability. The technique of diffusive gradients in thin films (DGTs) has also been employed to assess the concentration of metals in freshwater and marine environments, determining their lability. The present work evaluated and compared the labile and bioavailable concentrations of Cd, Co, Cu, Mn, Ni and Pb in seawater from Ilha Grande Bay, RJ, using DGT and transplanted bivalves (Nodipecten nodosus), respectively. The scallops and DGTs were immersed in water at three sampling locations within the bay from July to September 2012 (winter campaign) and from December 2012 to February 2013 (summer campaign). The metals were determined by inductively coupled plasma-mass spectrometry (ICP-MS) and optical emission spectrometry (ICP-OES). DGT technique was successfully used to determine the concentrations of metals in waters, except for Pb when short deployment times were used. All metals were determined using transplanted bivalves (N. nodosus), but pre-exposure to Cd was evident, which made the interpretation of the data for this analyte difficult. The data on metal lability in Ilha Grande Bay waters obtained from the DGT technique were correlated with the metal bioavailability determined in the soft tissues of the transplanted N. nodosus for Co, Cu, Mn, Ni and Pb. This is the first evaluation of this type for this area of high environmental concern. Both techniques revealed that Náutico was the location with the highest concentration of metals in the study area.     

Manganese toxicity in tomato plants: Effects on cation uptake and distribution

Two experiments are described in which tomato plants (Lycopersicon esculentum L. var Ailsa Craig) were grown in water culture supplied with 10–300 μM Mn. Toxicity symptoms associated with a yield reduction were observed only in treatments in excess of 50 μM Mn indicating that this species is relatively tolerant of high Mn supply. Dark brown/black spots appeared first in the cotyledons. Similar symptoms were observed in the leaves, progressively from the oldest leaf. Manganese concentration in the shoot tissues ranged from 286 to 4240 μg. g^‐1 dry weight. The high Mn concentration values found in the shoot tissues of the toxic plants indicate that Mn was highly mobile in the xylem as confirmed by xylem sap analysis.

The concentrations of both Ca and Mg were lower in the smaller Mn toxic plants. Not only was uptake of Ca and Mg retarded but so also was the distribution of Ca and Mg to the younger tissues as illustrated by measurements of Ca and Mg concentrations along a leaf age sequence. This is in accord with the cation‐anion balance of the xylem exudates collected from decapitated plants.

Higher cation exchange capacity (CEC) was found in the leaf tissues of toxic plants particularly in the older leaves but similar values of C.E.C were recorded for the younger leaf tissues of both control and toxic plants.     

Manganese Uptake and Accumulation by Two Populations of Phytolacca acinosa Roxb. (Phytolaccaceae)

Phytolacca acinosa (Phytolaccaceae) is a recently discovered manganese hyperaccumulator plant from Southern China. Manganese uptake and accumulation by two contrasting populations of P. acinosa were investigated. One population (MP) was from Xiangtan manganese tailings and the other (NMP) was from a Magnolia grandiflora plantation with lower Mn status. In addition to these field investigations, seedlings of the two populations were raised under glasshouse conditions to study biomass production and Mn uptake from nutrient solutions supplemented with increasing amounts of Mn (5, 1000, 2000, 5000, and 8000 μmol L^?1 Mn). Although, concentrations of Mn in the plant tissues (leaves, stems and roots) of P. acinosa (MP) and the associated soil from manganese tailings were significantly higher than those of the plant tissues and the soil collected in the clean site, significant differences were not found between the two populations of P. acinosa grown in nutrient culture. The two populations of seedlings showed similar growth responses, manganese uptake and accumulation when exposed to the same level of Mn supply for 45 days. All these results suggest that both high tolerance and hyperaccumulating ability of Mn in P. acinosa are constitutive properties. Furthermore, the plant grows rapidly, produces substantial biomass, and has broad ecological amplitude. P. acinosa, therefore, offers great potential for use in the phytoremediation of Mn-contaminated soils.     

Effect of manganese on endomycorrhizal sugar maple seedlings

Abstract

Manganese (Mn) toxicity may play an important role in the poor survival of seedlings in declining sugar maple (Acer saccharum Marsh.) stands in northern Pennsylvania. To determine the effect of Mn on the growth of sugar maple seedlings, 1‐year‐old seedlings inoculated with vesicular‐arbuscular mycorrhizal (VAM) fungi and growing in sand‐vermiculite‐peat moss medium were irrigated for 7 weeks with nutrient solution (pH 5) containing 0.1 (control), 1, 2, 4, 8, or 16 mg L^?1 Mn. Total seedling dry weight was negatively correlated with Mn, becoming significantly different than the control at 2 mg L^?1 Mn. Stem and root dry weight were reduced by lower Mn levels than leaf dry weight. Manganese had no effect on the root/shoot ratio. The concentration of Mn in roots and leaves increased as the level of Mn in the nutrient solution increased, with the concentration in the leaves 2.2‐ to 3.7‐fold greater than the concentration in the roots. Except for a reduction of P in the roots, Mn had little effect on the concentration of nutrient elements in the roots or leaves. Colonization of the roots by VAM fungi was increased by Mn, with a maximum percentage at 4 mg L^?1 Mn. Manganese toxicity symptoms in the leaves, small discrete chlorotic spots, began to appear at 1 mg L^?1 Mn. The sensitivity of sugar maple seedlings to Mn found in this study supports the hypothesis that Mn may affect regeneration in declining sugar maple stands. However, evaluation of the effects of Mn on seedlings in native soils under field conditions will be necessary before the role of Mn in sugar maple regeneration can be understood.     

Soil‐plant manganese relationships with emphasis on soybeans

Abstract

Manganese deficiency of soybeans is very prevalent in the United States. This deficiency occurs most frequently on poorly‐drained, sandy‐textured soils with water pH levels of approximately 6.0 or above. Yield increases of as high as 2,520 kg of soybean seed/ha have been obtained from correction of Mn deficiency. Manganese deficiency of soybeans can be corrected by band, broadcast or foliar application of Mn. Foliar application of Mn generally is the most convenient and economical method for alleviating Mn deficiency in soybeans. This review covers soil‐plant relationships of importance in diagnosis and correction of Mn deficiency in soybeans.     

Effect of soil pH on mineral element concentrations of two erythroxylum species

Erythroxylum coca var. coca Lam. (E. coca) and Erythroxylum novogranatense var. novogranatense (Morris) Hieron (E. n. novogranatense) are two of four Erythroxylum species grown in the tropics of South America for cultural medicines and the alkaloid benzoylmethylecgonine. In a published study of biomass production over a soil pH range of 3.5 to 7.0, E. coca grew best at a pH equal to and below 5.5, and E. n. novogranatense grew best within the pH range of 4.7 to 6.0. Erythroxylum coca was tentatively classified as more tolerant to metal toxicities [aluminum (Al) and manganese (Mn)] than E. n. novogranatense, however, concentration patterns of mineral elements for E. coca and E. n. novogranatense tissue have not been reported, nor have the mechanisms of differential acid‐soil‐tolerance been elucidated. In the current study, the effects of soil pH on concentrations of Al, calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), Mn, and zinc (Zn) in leaves, stems, and roots were investigated. At pH 3.5, roots of both species accumulated high concentrations of Al that decreased as soil pH increased, however, there was no pH × species interaction. The highest concentration of Ca was found in the leaves of both species, however, E. coca accumulated more Ca as soil pH increased than did E. n. novogranatense. Manganese and Zn levels were highest in roots of both species (E. coca and E. n. novogranatense); levels in all tissues decreased with increasing pH. Manganese concentration was highest in roots of E. coca and Zn concentration was highest in tissues of E. n. novogranatense. Copper, Fe, K, and Mg levels were erratic with increasing pH, indicating that sufficient amounts of these nutrients are acquired at low pH levels. Root concentrations of Fe and K in E. coca increased markedly between pH 3.5 and 4.7. At pH 3.5, E. coca demonstrated no symptoms of mineral deficiency and/or toxicity, however, chlorosis, leaf distortion and root atrophy were prevalent at pH 6.5 and 7.0. By contrast, E. n. novogranatense demonstrated diminished growth and root atrophy at soil pH 3.5, whereas at pH 6.5 and 7.0, although biomass production was reduced, no symptoms of mineral deficiency and/or toxicity were present. The species obviously behave differentially at pH extremes and E. coca appears to be most tolerant of extremely acid soils; the two species may also differ in mineral sensitivities between the species at higher pH levels. Erythroxylum coca may compete more effectively with Al for Ca binding sites within the root, and may have greater internal tolerance of Mn, compared with E. n. novogranatense.     

Distribution of Trace Elements in Tissues of Two Shrimp Species from Persian Gulf and Effects of Storage Temperature on Elements Transportation

This study is focussed on evaluation of temperature effectduring frozen storage on movement of trace elements in differenttissues (exoskeleton, carapace and abdominal muscle) of twocommercially important shrimp species (Penaeusmerguiensis and Metapenaues affinis). Moreoverrelationships between total length and sex of specimens with concentration of trace elements in selected tissues were assessed. Concentrations of Cd, Cr, Cu, Fe, Mn, Ni and Znin samples were determined by ICP-AES. Only in the case of Niand Zn sex related differences could be observed. With theexception of Cu, the trace metals distributed significantlydifferent between the tissues. The only significant differencesbetween species were found in bioaccumulation of Mn. Sizedependent relationship was observed only for Ni. Associationsbetween Mn and Fe were positively and highly significant in allthe cases. The levels of all the metals in muscle of the shrimpsfrom the studied region were comparable to other world areas. MeanCu and Zn levels in edible parts of M. affinis stored at–10 °C exceeded some existing guidelines, while the concentrations at –30 °C were somewhat lower than them.     

Effects of excess soil manganese on stomatal function in two soybean cultivars

Manganese tolerant ‘Lee’ and Mn sensitive ‘Forrest’ soybean cultivars were grown in a potting soil with no known Mn toxicity and in Loring soil treated with excess Mn. Manganese toxicity in Loring soil was induced by the addition of Mn at 0, 100, 200 and 400 ug g^‐1 as MnSO₄.H₂O. A preliminary experiment was conducted to determine the appropriate Mn stress levels for Lee and Forrest soybean cultivars in Loring soil. Because the Loring soil produced severe Mn toxicity in both cultivars, even with an intial pH of 4.9 and no added Mn, CaCO₃ (2 g kg^‐1 ) was added to Increase the pH to 6–6.3. Soil was analysed for extractable and water soluble Mn and plants for Mn, Ca and Fe.

A second experiment was conducted to determine the effect of Mn toxicity on stomatal function. The procedure was the same as in the first experiment except that the CaCO₃ treatment was 2.5 g kg^‐1 to raise soil pH to 6.2 ‐6.5. Plants were grown in a greenhouse for 10 days and then moved to a growth chamber before making stomatal conductance measurements. A steady state porometer (LI 1600) was used. Results indicated that Mn toxicity closed stomates and decreased transpiration rates. This effect was more pronounced in Mn sensitive Forrest than in Mn tolerant Lee.     

The Morphophysiological Responses of Free-Floating Aquatic Macrophytes to a Supra-optimal Supply of Manganese

Among the many anthropogenic abiotic stresses, manganese (Mn) toxicity has been recognized for its impact on aquatic ecosystems as well as on the biological components of these ecosystems, including aquatic plants. The objective of this study was to determine the Mn accumulation ability of aquatic macrophytes (Azolla caroliniana, Salvinia minima and Spirodela polyrhiza) and evaluate the morphophysiological responses of the species that gather the highest amount of Mn when exposed to a supra-optimal supply of manganese. The experiments were conducted in the laboratory, and the effects of Mn were evaluated based on plant growth; the concentration of total chlorophyll, carotenoids, and anthocyanins; the enzymatic activity of catalase and peroxidase; and leaf anatomy. All of the studied species accumulated Mn in their tissues. Moreover, it was observed that this accumulation was dependent on the concentration of the metal in solution. S. polyrhiza showed higher concentrations of Mn in its tissues (17.062?mg?g^?1 dry weight (DW)), followed by S. minima (4.283?mg?g^?1 DW) and A. caroliniana (1.341?mg?g^?1 DW). Despite the Mn accumulation in all species, S. polyrhiza was the only one selected for further analyses because of its greater ability to accumulate Mn. The high Mn concentration found in tissues of S. polyrhiza suggests that this species has the potential to sequester and accumulate this metal. However, a sensitive response in the plants exposed to higher Mn concentrations (0.4?mM) was observed. The phytotoxicity effects of this accumulation were responsible for a decrease in the plant growth, a reduction in the pigment content (total chlorophyll, carotenoids, and anthocyanins), a low activity of catalase, and the disarrangement of the leaf aerenchyma.     

Manganese and molybdenum contents of the cotton plant at different stages of growth

Abstract

Manganese and molybdenum levels in cotton plants belonging to 4 cultivated species and an interspecific hybrid were determined from seedling stage to crop maturity. Irrespective of the species 10 day old seedlings had maximum Mn and Mo. The diploids had higher seedling Mn than tetraploids. There was a sharp fell in leaf and stem Mn with flower bud formation and a similar fall in root Mn from peak flowering. At crop maturity Mn content of leaves, stem and root was the same for different cultivars. Mn content of lint of tetraploids was nearly three times than in diploids.

After seedling stage maximum Mo was in leaves from flower bud initiation to peak flowering and declined rapidly at boll bursting. From square stage Mo in stem fell gradually until harvest whereas in root it remained at more or less the same level with slight differences and fell appreciably at early boll bursting and harvest. Like Mn, at maturity Mo content on unit weight basis was the same. The burs of tetraploids and the hybrid had little more Mo. The seeds of the Gossypium arboreum cultivar and the hybrid contained less Mo than other cultivars.

The levels of Mn at early stages of growth were higher than the toxicity limits reported previously. Similarly at no stage the upper limits of Mo concentration reported earlier could be recorded. The higher levels of Mn recorded in field grown plants caused no toxicity symptoms.     

Iron chelate inducible iron/manganese toxicity in zonal geranium

Leaf symptoms of a physiological disorder of cutting geranium (Pelargonium x hortorum L.H. Bailey ‘Aurora') were induced with FeDTPA treatments ranging from 0.02 mM (1 ppm) to 1.12 mM (60 ppm) applied to a soilless peat‐based medium. Symptoms included marginal/nterveinal chlorosis that progressed to marginalAnterveinal necrosis and in extreme cases whole leaf necrosis. Iron (Fe) concentration increased with increasing FeDTPA level in both symptom and asymptom tissues. Within the same FeDTPA treatments symptom tissue had higher concentration of Fe and manganese (Mn) than asymptom tissue. Manganese in symptom tissue decreased as FeDTPA level increased; whereas Mn concentration of asymptom tissue were similar among all FeDTPA treatments. Preplant addition of dolomite to maintain medium pH within the range of 5.8–6.2 lowered Fe and Mn concentration in both symptom and asymptom tissue and medium leachates; however, liquid dolomite drenches during the crop cycle had little effect on tissue Fe and Mn. This disorder results from increased levels of Fe and Mn in the plant tissue and should be referred to as Fe/Mn toxicity.     

Sulphur gas emissions in the boreal forest: The West Whitecourt case study VIII: Pine tree mineral nutrition

Nutrient analyses of foliage from a naturally occurring hybrid of Pinus contorta Loud. and P. banksiana Lamb. (lodgepole pine × jack pine), were used to determine if chronic exposure to S gas emissions had affected the nutrient status of the trees. This study was part of a larger case study investigating the effects of 17 yr of exposure to S gas emissions from a S-recovery gas plant on a forest ecosystem in west central Alberta, Canada. Significant inverse, linear relationships were found between foliar sulphate-S levels and distance from the S source in all three age classes of pine foliage tested. Sulphate-S levels increased with increasing age of foliage at sites near the source while they decreased with increasing age of foliage at sites not frequently exposed to the S gas emissions. Soil pH was reduced in the top 5 cm of soil at sites near the source and elevated contents of total S in the soil were also found at those sites. Manganese concentrations in foliage from the sites near the source were significantly higher than in foliage from sites away from the source. The level of Mn also increased with increasing age of tissues. The elevated level of sulphate-S in foliage and lower soil pH at sites near the source indicated significant amounts of S from the source had been deposited at those sites. The lower soil pH most likely contributed to the increased availability of Mn that was found in the foliage.     

Diversity in tree species in Southeastern Ohio Betula nigra L. Communities

Quantitative data were obtained for arboreal species within 50 lowland forests in southeastern Ohio. Thirty-seven communities were dominated by Betula nigra L. and 13 were dominated by Acer saccharinum L. The acidic soils collected from B. nigra communities contained toxic concentrations of exchangeable Al and low concentrations of Ca and Mg. Tree species diversity (Shannon-Weaver index) and species equitability were inversely related to high concentrations of exchangeable Al and H and directly related to high concentrations of exchangeable Ca and Mg and an increase in soil pH.     

Biomonitoring of Trace Metals (Fe, Cu, and Ni) in the Mangrove Area of Peninsular Malaysia Using Different Soft Tissues of Flat Tree Oyster Isognomon alatus

It is well documented that marine oysters are net bioaccumulators of trace metals and they can be employed as biomonitors of time-integrated measurements of bioavailable metal fractions over their lifetime. In this study, the Malaysian mangrove flat tree oyster Isognomon alatus collected from the estuaries of Lukut River (five sites), Sepang Besar River (one site), and one metal-polluted site at Kg. Pasir Puteh were dissected into muscle, mantle plus gills, byssus, and remaining soft tissues. All the four different soft tissues were analyzed for Fe, Cu, and Ni. Significant spatial differences in the accumulated metal concentrations of the oysters were found between sampling sites, and these could be attributed to anthropogenic inputs including discharges of shrimp ponds (Lukut), animal husbandry (Sepang Besar), sewage, shipping, and industrial effluents (Kg. Pasir Puteh). For Fe, the tissue distribution followed: byssus > mantle plus gill >muscle > remaining soft tissues, while for Cu and Ni, both followed byssus > remaining soft tissues > mantle plus gill > muscle. This indicated that byssus could act as an excretion route for the metals. Based on a correlation analysis between oyster tissues and sediments, selected tissues of I. alatus were shown to be good biomonitors of Ni and Cu contamination, while high regulative capacity of Fe in the oyster tissues could hardly reflect the actual Fe levels in the surroundings. However, the clustering patterns based on metal levels in the four different soft tissues were not in agreement with those based on the geochemical fractions of sediment data. This phenomenon which was due to the metal contamination might not necessarily create high bioavailabilities of metals to the biomonitor I. alatus, which might involve differences in uptake, excretion, and sequestration of metals. Similarly to the Mussel Watch approach, this study points to the very potential use of the different soft tissues of I. alatus as biomonitors for regular biomonitoring in the mangrove area of Peninsular Malaysia.     

Mechanism of manganese toxicity and tolerance of plants VI. Effect of silicon on alleviation of manganese toxicity of barley

Effect of Si on alleviation of Mn toxicity of barley (Hordeum vulgare L.) seedlings was investigated with special reference to the effect on Mn microdistribution and peroxidase activity. Manganese treatment was conducted by growing the seedlings in nutrient solutions containing different concentrations of Mn. Silicon treatment was conducted by growing the seedlings in the solutions with or without Si supply. Silicon supply alleviated the necrotic browning in the leaves but did not affect the chlorosis caused by Mn toxicity. Silicon treatment did not appreciably alter the uptake of Mn by the plants. Electron probe X‐ray microanalysis revealed that Mn accumulated in high concentration around the necrotic brown spots and that Si supply prevented the uneven distribution of Mn in the tissues. Increase in the level of Mn supply caused an increase in peroxidase activity in the tissues, and Si supply prvented the increase in peroxidase activity.     

Heavy Metal Levels in Muscle Tissues of <Emphasis Type="Italic">Solea solea</Emphasis>, <Emphasis Type="Italic">Mullus barbatus</Emphasis>, and <Emphasis Type="Italic">Sardina pilchardus</Emphasis> Marketed for Consumption in Mersin,Turkey

Edible muscle tissues of Solea solea, Mullus barbatus, and Sardina pilchardus marketed in Mersin were analyzed for their Cr (total), Mn, Fe, Ni, Cu, Zn, As (total), Cd, Sn, and Pb levels. Metal levels of the tissues were determined using inductively coupled plasma-mass spectrophotometric (ICP-MS) methods. Muscle levels of Cr, Mn, Fe, Ni, Cu, Zn, As, Sn, and Pb were determined as 0.19–2.80, 0.08–3.88, 0.93–25.76, 0.03–0.63, 0.01–1.96, 1.28–45.95, 0.49–25.26, 0.14–4.03, and 0.02–1.37 mg kg^?1 w.w., respectively. Cadmium levels were below detection limits in all the muscle samples taken. Mean metal levels of the tissues were compared with the provisional tolerable daily (PTDs) and weekly (PTWIs) intake limits. Mean metal levels taken by the consumption of analyzed tissues were below PTDs and PTWIs; hence, the fish species studied do not pose any risk for human consumption from the point of heavy metals.     

A New Application for <Emphasis Type="Italic">Klebsiella oxytoca</Emphasis> in Bioremediation: Treatment of Manganese-Laden Wastewaters

Bioremediation is a method of removing manganese from wastewaters, and many bacterial species with a role in manganese bioremediation have been identified over several decades. Using K medium with Mn(II), a bacterial consortium was obtained from water sample collected from a mine drainage in southeastern Brazil (Minas Gerais, Brazil), and the isolates were identified as Klebsiella oxytoca using both biochemical and 16S rRNA phylogenetic analysis. Among such isolates, sample SA8 was tested for its manganese removal capability during a week-long experiment in K medium amended with manganese sulfate. Growth of isolate SA8 produced an increase in pH concomitantly to Mn(II) removal, which was not observed in the abiotic control. Manganese removal occurred through oxidation as confirmed by reaction with leucoberbelin blue, and therefore, a new potential application for K. oxytoca in mine water bioremediation is proposed.     

Minor Elements and Trace Metals in the Shell of Marine Gastropods from a Shore in Tropical East Africa

The concentrations of minor elements (magnesium and strontium)and trace metals (iron, manganese, copper and zinc) in the shellof fifty-nine species of marine gastropod collected from a shorein tropical East Africa are reported. Mean trace metalconcentrations and range of concentrations in the fifty-threespecies having an aragonitic shell were: iron, 17.5 μg g^-1, range 7.2 to 30.6 μg g^-1; manganese 2.4 μgg^-1, range 1.8 to 3.4 μg g^-1; copper, 1.2 μgg^-1, range 0.6 to 2.4 μg g^-1 and zinc, 1.5 μgg^-1, range 0.8 to 2.6 μg g^-1. The six species ofthe Nerita included in the study all had a shell of mixedmineralogy, a high magnesium concentration (2550 to 3407 μgg^-1) and relatively elevated concentrations of the tracemetals, manganese, copper and zinc (mean concentrations, 7.5,3.4 and 5.5 μg g^-1, respectively). Highestconcentrations of all three metals occurred in the shell of N. albicilla. Manganese, copper and zinc concentrations inshells of a population of N. albicilla (n = 20) taken fromthe Kenyan coast were higher than those in a similar populationof shells taken from Aldabra Atoll (Seychelles) by factors of29, 10 and 2.6, respectively. Of the fifty-nine species ofmarine gastropod included in this study the shell of N.albicilla is identified as having the greatest potential as abiomonitoring tissue for trace metals.