Accumulation Of Trace Elements Research Articles

Zircon from the Turga Multiphase Massif with Amazonite Granites (Eastern Transbaikalia) and Its Petrogenetic Significance

Zircon from granitoids of the multiphase Turga massif (Eastern Transbaikalia) shows various morphological features and compositions of trace elements. This granitoid massif of the Kukulbey complex is spatially associated with rocks of the Shakhtama monzonitoid complex, whose ages are about 133 and 158 Ma, respectively. Zircon from different granitoid phases of the Kukulbey complex demonstrates a decrease in Hf content and an increase in Th, U, Y, and REE concentrations. The trace element accumulation in zircon and rocks of the main phase of the Turga massif (Li-Li-siderophyllite granites) was accompanied by a significant rise of their crystallization temperature, relatively to the earlier phase. The indicative features of zircon in these granites—the intensive development of specific twinning (up to 30% of all grains) and the presence of contrasting growth zones—confirm the idea of increasing crystallization temperatures and alkalinity of the melt. These features of zircon, together with geochemical composition of rocks, indicate that amazonite granites of the Turga massif belong to the alkaline type of Li–F-bearing granites with a mixed geochemical specialization: on the one hand, Li, Ta, and Nb, which are typical for the ore-bearing (peraluminous rare-metal) Orlovka massif; and on the other hand, Zr, REE, Th, and U, which are more typical for alkaline granites.

Accumulation of trace elements in leatherback turtle (Dermochelys coriacea) eggs from the south-western Caribbean indicates potential health risks to consumers.

Trace metal and metalloid levels were measured in eggs of the NW Atlantic leatherback turtle (Dermochelys coriacea) from nesting grounds in the Bocas del Toro province, Panama, to infer exposure and associated risks to local communities. Samples were analyzed for a set of 26 essential and non-essential elements using inductively coupled plasma techniques. Median concentrations of Fe, Zn, As, Se and Sr in D.coriacea eggs were higher than previously reported for this species, which likely reflects differential contamination levels of specimens during foraging. The evaluation of non-carcinogenic human health risks from ingesting leatherback eggs has revealed potential deleterious effects due to high concentrations of As, Se and Sr for all examined age and gender groups, while Hg and Zn levels were above international standards for children. Hazard index (HI) values exceeded unity in all cases indicating serious health impacts related to possible additive effects of multiple metals co-occurring in the eggs. Our findings suggest that exposure to high (inorganic) As and Cr(VI) levels is associated with an increased carcinogenic risk, significantly exceeding the acceptable lifetime risk of 10-6 for both adults and children. Despite some limitations, such as unclear As and Cr speciation, our results demonstrated that the ingestion of D.coriacea eggs poses considerable health risks to local communities, and their consumption should not exceed 3.4×10-4g (5.0×10-6 eggs) kg BW d-1. Resource managers and conservationists should focus their attention to human health effects as an alternative tool to address egg poaching and consumption.

Environmental-friendly Contamination Assessment of Habitats Based on the Trace Element Content of Dragonfly Exuviae

We tested the usefulness of exuviae as an environmentally friendly method for exploring the variability of the trace element contents of protected insect populations without killing specimens. It is a notable characteristic of dragonflies that they are good ecological indicators for both aquatic and terrestrial habitat quality. Thus, we investigated the trace element accumulation in different stages of dragonflies: larva, exuvia, and adult. Using microwave plasma atomic emission spectrometry (MP-AES), we analysed the concentrations of Al, Ba, Cr, Cu, Fe, Mn, Pb, Sr and Zn. We found that the trace element contents of exuviae are a good proxy of the trace element contents of both the larvae and the adults. We conclude that exuvia is useful for assessing the environmental health of aquatic ecosystems. It is an environmentally friendly method and it can be used even in the case of protected dragonfly species.

Basins, beaver ponds, and the storage and redistribution of trace elements in an industrially impacted coastal plain stream on the Savannah River Site, SC, USA

Accumulation of eleven trace elements in sediment was evaluated throughout an industrially disturbed headwater stream on the Savannah River Site, SC, USA. Sampling began at upstream sedimentation basins at the margins of industrial areas, continued longitudinally downstream to a beaver pond representing a potential sink in the mid-reaches, and ended in downstream reaches. Additionally, sediment from beaver impacted areas in another industrially disturbed stream and a reference stream were analyzed to assess the natural tendency of these depositional features to settle out trace elements. We further compared trace element accumulation in sediment and biota from downstream reaches before and after an extreme rainy period to evaluate the potential redistribution of trace elements from sink areas. Trace elements accumulated in the headwater basins from which elements were redistributed to downstream reaches. The mid-reach beaver affected area sediments accumulated elevated concentrations of most analyzed elements compared to the free-flowing stream. The elevated accumulation of organic matter in these sink areas illustrated the effectiveness of reduced water velocity areas to settle out materials. The natural tendency of beaver ponds to accumulate trace elements and organic matter was further illustrated by sediments from the reference beaver pond accumulating higher concentrations of several elements than sediments from the free flowing section the stream impacted by industrial activity. However, concentrations in sediment from sedimentation basins and the beaver impacted area of the disturbed stream were highest. Trace elements and organic matter appeared to be redistributed from the sinks after the record rainy period resulting in increased trace element concentrations in both sediment and biota. These data suggest that assessments of contaminants in stream systems should include such slow-water, extreme depositional zones such as beaver impacted areas or basins to verify what contaminants may be pulsing through the stream.

Trace element analysis reveals bioaccumulation in the squid Gonatus fabricii from polar regions of the Atlantic Ocean

The boreoatlantic gonate squid (Gonatus fabricii) represents important prey for top predators—such as marine mammals, seabirds and fish—and is also an efficient predator of crustaceans and fish. Gonatus fabricii is the most abundant cephalopod in the northern Atlantic and Arctic Ocean but the trace element accumulation of this ecologically important species is unknown. In this study, trace element concentrations (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn) were analysed from the mantle muscle and the digestive gland tissue of juveniles, adult females, and adult males that were captured south of Disko Island off West-Greenland. To assess the feeding habitat and trophic position of this species, stable isotopes of carbon (δ13C) and nitrogen (δ15N) were measured in their muscle tissue. Mercury concentrations were positively correlated with size (mantle length) and trophic position. The Hg/Se ratio was assessed because Se has been suggested to play a protective role against Hg toxicity and showed a molar surplus of Se relative to Hg. Cadmium concentrations in the digestive gland were negatively correlated with size and trophic position (δ15N), which suggested a dietary shift from Cd-rich crustaceans towards Cd-poor fish during ontogeny. This study provides trace element concentration data for G. fabricii from Greenlandic waters, which represents baseline data for a northern cephalopod species. Within West-Greenland waters, G. fabricii appears to be an important vector for the transfer of Cd in the Arctic pelagic food web.

Relationship Between Major And Trace Elements In Ulaanbaatar Soils: A Study Based On Multivariate Statistical Analysis

This article focuses on the relationships between major (Si, Al, Mg, Fe, Ca, Na, K, S, P and Ti) and potentially toxic trace (Ag, As, B, Ba, Bi, Co, Cd, Cr, Cu, F, Ge, Mo, Mn, Li, Ni, Pb, Sb, Sn, Sr, Tl, V and Zn) elements in Ulaanbaatar surface soils and also sources of the trace elements in the soils distinguished by the methods of multivariate statistical analysis. Results of exploratory data analysis of 325 Ulaanbaatar soil samples show the accumulation of Ca, S, B, Bi, Cu, Mo, Pb, Sb, Sn, Sr and Zn in urban soils. The major elements were grouped by cluster analysis in tree associations characterizing main soil fractions: sandy P-(K-Na-Si), clayey (Mg-Ti-Fe-Al) and silty (S-Ca). The factor analysis shows that silty fraction is enriched in major elements of both natural and anthropogenic origin. The principal component analysis from 32 variables extracted nine principal components with 82.49% of the cumulative explained variance. The results of cluster and factor analyses well agree and reaffirm the enrichment causes of potentially toxic elements are a coal combustion at thermal power stations (B, Bi, Ca, Mo, S and Sr) and traffic emissions (Cu, Pb, Sn and Zn). Spatial distributions of trace elements in the districts of Ulaanbaatar city were obtained by ordinary kriging. It is illustrated that the different principal components define the various origins and patterns of accumulation of trace elements in soils. The supplementation of data set by the concentration of organic carbon and the species of elements could help to identify the sources of such elements as P, Ni, Al, Fe, Ca, Ba, Bi, Cr, Zn, Sr and Sb in urban soils more completely.

The alga Ulva lactuca (Ulvaceae, Chlorophyta) as a bioindicator of trace element contamination along the coast of Sicily, Italy

The marine environment is subjected to ever-increasing levels of contamination, especially along the coastal areas with urban and industrial activities. Consequently, monitoring campaigns on large scales should be conducted on a regular basis for a better management of marine ecosystems. This study tested the capacity of the green alga Ulva lactuca to act as a bioindicator of trace elements along the coasts of Sicily (Italy). The concentrations of the metals Cd, Cr, Cu, Ni, Pb and Zn were analyzed in samples of water, sediments and U. lactuca thalli, which were collected in ten different sites at diverse levels of human impact. The results showed that U. lactuca can accumulate essential and non-essential elements at similar concentrations. The analysis of trace elements showed also that the metal content in U. lactuca is significantly correlated with the levels of trace elements in water and sediments. U. lactuca fits numerous features that make it one of the best bioindicators of marine pollution, also thanks to its worldwide distribution and capacity to accumulate trace elements under toxic conditions. The use of U. lactuca should be encouraged to set up large-scale monitoring programs, especially in highly impacted seas like the Mediterranean where U. lactuca is widespread.

Composition and physico-chemical properties of bottom sediments in the southern part of the Bratsk Reservoir (Russia)

The paper presents the results of studies of bottom sediments taken from the southern part of the Bratsk Reservoir. The following analyses have been conducted: trace element analysis, particle-size analysis as well as chemical analysis of water, hydrochloric acid and alkaline extracts for 18 samples of the bottom sediments. The granulometric analysis has identified the predominance of fine silt and silty-clayed sediments. The data on the content of trace elements in the bottom sediments of the Bratsk Reservoir is presented in comparison with their content in the natural environment of the Baikal region; the anomaly ratio was used to characterize the excess for trace elements. The chemical analysis of extracts has showed “saline contamination” of mud (silt), high concentration of carbonates in it, as well as the presence of mobile (free) forms of aluminum oxide. In this research, an attempt was made by using a correlation analysis to evaluate the impact of various physical and chemical characteristics of the bottom sediments, such as the content of clay fraction, organic carbon, carbonates, and water-soluble salts on the accumulation of trace elements.

Uptake of trace elements by food crops grown within the Kilembe copper mine catchment, Western Uganda

The mining and processing of copper from the Kilembe mine between 1956 and 1982 left behind millions of tons of cupriferous and cobalt ferrous mine tailings within the Kilembe mine catchment. Subsequent erosion and deposition of the tailings into adjacent areas led to increased concentrations of Cu, Co, Ni, Zn, and Pb in the catchment soils. The Kilembe catchment is utilised for subsistence farming, producing mainly food crops, but there are also a number of settlements in the contaminated area. A study was conducted in 2016 to establish the concentrations of trace elements in a range of food crops grown within the catchment. Samples of maize, bananas, cassava, sweet potatoes, ground nuts, amaranthus, onions, beans and yams were collected, washed and oven dried at 80 °C. The dried foods were finely ground, microwave- digested in nitric acid and analysed using inductively coupled plasma mass spectrometry (ICPMS). All the foods grown in contaminated soils showed instances of higher concentrations of Cu, Co, Ni, Zn, and in some cases Pb, compared with controls grown in uncontaminated soils. Amaranthus accumulated a range of trace elements with 26% of the samples exceeding EC thresholds for Cu in vegetables of 26 mg kg−1.Other crops with elemental concentrations exceeding recommended thresholds in some of the samples included beans (Zn), yams (Zn and Pb) and ground nuts (Zn). The concentrations of trace elements in onions, cassava, sweet potatoes, bananas and maize were not significantly different from controls. However, strong and positive correlations between the trace elements were found in beans, yams, amaranthus, maize and ground nuts, suggesting a common source of trace metals. There was strong evidence of soil dust retention on leaf vegetables (Amaranthus) despite washing. The accumulation of trace elements in the edible parts of vegetables and foods could have a direct impact on the health of local people, because the foods produced from gardens are mostly consumed locally.

Poplar rotation coppice at a trace element-contaminated phytomanagement site: A 10-year study revealing biomass production, element export and impact on extractable elements

Growing lignocellulosic crops on marginal lands could compose a substantial proportion of future energy resources. The potential of poplar was explored, by devising a field trial of two hectares in 2007 in a metal-contaminated site to quantify the genotypic variation in the growth traits of 14 poplar genotypes grown in short-rotation coppice and to assess element transfer and export by individual genotypes. Our data led us to conclusions about the genotypic variations in poplar growth on a moderately contaminated site, with the Vesten genotype being the most productive. This genotype also accumulated the least amounts of trace elements, whereas the Trichobel genotype accumulated up to 170 mg Zn kg−1 DW in the branches, with large variation being exhibited among the genotypes for trace element (TE) accumulation. Soil element depletion occurred for a range of TEs, whereas the soil content of major nutrients and the pH remained unchanged or slightly increased after 10 years of poplar growth. The higher TE content of bark tissues compared with the wood and the higher proportion of bark in branches compared with the wood led us to recommend that only stem wood be harvested, instead of the whole tree, which will enable a reduction in the risks encountered with TE-enriched biomass in the valorization process.

Evaluation of trace element contamination usingArmadillo officinalisDuméril, 1816 (Crustacea, Isopoda) as a tool: An ultrastructural study

To estimate trace element bioaccumulation in Armadillo officinalis, specimens were collected from Ghar El Melh lagoon then exposed for 3 weeks in contaminated sediments with copper, zinc, and cadmium. From the first week until the end of the experiment, a decrease in A. officinalis growth related to the increase of Cd concentration in the sediment was recorded. However, a mass gain was highlighted under Cu and Zn exposures. At the end of experiment, body metal concentrations were measured using flame atomic emission spectrometry. Results of the bioaccumulation factor showed that the species could be considered as a macroconcentrator of copper (BAF > 2) and a deconcentrator of zinc (BAF < 2). Microscopy observations of hepatopancreas cells showed morphological and histological changes even at the lowest concentration. They consisted in the microvillus border destruction, lipid droplets modifications, trace element accumulation, and the condensation of the majority of cellular organelles. The degree of these alterations was found to be dose-dependent. Through these results, the isopod A. officinalis could be used as relevant monitor organisms for soil metal contamination.

Trace element accumulation in Salvinia natans from areas of various land use types

Salvinia natans meets many criteria for accumulative bioindicators and phytoremediation agents. However, the majority of studies on its bioaccumulation capacity were performed under controlled culture conditions. In the present study, Salvinia natans was investigated in a field study. Plant and water samples were collected from aquatic reservoirs located in areas with various dominant land uses (forested, agricultural, residential and industrial). Contents of 10 trace elements (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) and phytomass were measured to estimate the bioindication and phytoremediation potential of the species. Results showed that contents of trace elements in S. natans were high compared with other aquatic ferns (Azolla japonica, A. pinata) as well as free-floating vascular plants (e.g. Pistia stratiotes, Hydrocharis morsus-ranae, Lemna sp., Eichhornia crassipes). High bioaccumulation factors for Cu, Fe, Mn, Ni, Pb and Zn confirm accumulative abilities of the plant. Application of neural networks (SOFMs) confirmed that the species may be used in bioindication: the land use type determined the composition of substances carried into water reservoirs with runoff and trace elements accumulated in Salvinia tissues. Ferns in industrial areas had the highest content of Cd, Cu and Zn, while in residential areas plants showed the highest content of As, Co, Fe, Mn, Ni and Pb. Element contents in S. natans in forested areas were the lowest. High standing stocks of Cd, Mn and Ni indicated an important role of S. natans in the cycling of elements and potential use in their removal from aquatic ecosystems.

Assessment of trace element accumulation potential of Noccaea kovatsii from ultramafics of Bosnia and Herzegovina and Serbia.

In this work, we present the results of the investigation of trace elements (Fe, Mg, Ni, Zn, Cu, Cr, Co, Cd, Pb) accumulation potential of Noccaea kovatsii (Heuff.) F. K. Mey., from the Balkan Peninsula. The study included eight populations from ultramafic soils, six from Bosnia and Herzegovina, and two from Serbia. Principal component analysis (PCA) was used to reveal relationships of elements in soil, and Pearson's correlation coefficients for analysing associations of available quantities of elements in soil and those in roots and shoots of N. kovatsii. Uptake and translocation efficiency was assessed by using bioconcentration (BCF) and translocation factors (TF). All the analysed populations of N. kovatsii emerged as strong Ni accumulators, with the highest shoot concentrations of 12,505 mg kg-1. Even thought contents of Zn in plant tissues of N. kovatsii were under the hyperaccumulation level (602 mg kg-1 and 1120 mg kg-1 respectively), BCF was up to 667, indicating that certain surveyed populations have strong accumulative potential for this element.

Accumulation of Essential and Trace Elements in Guar (Cyamopsis tetragonoloba) and Guar Gum Cultivated in Semi-arid Regions of Sindh, Pakistan.

For physiological and biochemical studies, it is considered essential to have knowledge about the accumulation of mineral elements in plants and their distribution in different parts of the fruit and these data being essential for geographical origins of different food commodities. In the age of food industry globalization, the origin of food is essential to know for human health protection, to stimulate fine agronomic actions and to bar the use of toxic materials to stimulate plant's growth. This research work was formulated to assess the essential trace and toxic elements in Guar (Cyamopsis tetragonoloba) and guar gum cultivated in semi-arid regions of Sindh, Pakistan. For pretreatment of the guar samples, microwave-assisted acid digestion procedure (MAD) was developed for the elemental analysis in the guar samples. The validity of designed method was checked by using certified reference samples of BCR 189 whole meal flour. The digested specimens were analyzed by flame and graphite furnace atomic absorption spectrophotometry. The concentration of essential trace and toxic elements was found to be within the international level. In addition, human health Risk assessment was accessed by measuring daily intake of all understudy minerals, which was within permissible exposure limit set by USEPA & Health Canada. The Target Hazard Quotient (THQs) of guar and its gum were generally less than 1, as per USEPA; owing to these facts, food grade guar gum can be produced from guar cultivated in Thar, Pakistan.

Trace elements in Endectyon fruticosa collected from a sewage outfall site, Therespuram, Tuticorin coast, India

Gulf of Mannar biosphere reserve extends from Rameswaram to Tuticorin coast supporting a large biodiversity of marine organisms especially corals and sponges. During recent past, Tuticorin has become a major recipient of contaminants from both domestic and industries surrounding the coast. The sewage outfall site located close to the sea which is directly dumping its effluents into the open sea has resulted in the significant enrichment of trace elements (TEs). Samples of seawater and Endectyon fruticosa were collected at three different stations (S1, S2 and S3) along a gradient of distance from sewage outfall site, and the six TEs Pb (lead), Mn (manganese), Ba (Barium), V (vanadium), Mo (molybdenum) and Sb (antimony) were measured in seawater and tissues of E. fruticosa using Inductively Coupled Plasma Mass Spectrophotometer (ICP-MS). Station S1 close to the sewage outfall site has shown high concentration of Pb, Mn, Ba, V, Mo and Sb when compared to far regions (S2 and S3). The decreasing order of accumulation of TEs in both seawater and E. fruticosa was same order of magnitude in all the collected three stations (S1, S2 and S3) Pb > Mn > Ba > V > Mo > Sb. The concentration of TEs in seawater and E. fruticosa were relatively more near the sewage outfall site when compared to the other far regions. Thus, E. fruticosa can be used as an effective biomonitor to evaluate the concentration of TEs from point source (S1) to far regions (S2 and S3).

A comparative study of the accumulation of trace elements in Brassicaceae plant species with phytoremediation potential

Native plant species growing on contaminated sites in an urban environment successfully develop under strong anthropogenic pressure and thereby may have the potential for phytoremediation. The concentrations of potentially toxic metals were measured in leaves, roots, stems, and inflorescences of fifteen Brassicaceae plant species from the urban park of Botanical Garden of Komarov Botanical Institute. The potential of phytoextraction and phytostabilization of the species was evaluated considering the concentration of Cd, Cu, Ni, Pb, Zn in the plant organs, and the bioconcentration factor (BCF) and the translocation factor (TF). The metal content in plant organs varied with plant species. The study of metal accumulation in plants showed that Brassica campestris has the potential for the simultaneous phytoextraction of three metals Zn, Cd, and Cu, and Rorippa palustris – of two metals Zn and Cd. According to received data, species Sinapis arvensis and Thlaspi arvense can be considered adequate candidates for soil Zn and Pb phytostabilization and soil conservation.

Natural and anthropogenic oil impacts on benthic foraminifera in the southern Gulf of Mexico

The Campeche Sound is the major offshore oil producing area in the Southern Gulf of Mexico (SGoM). To evaluate the impact of oil related activities in the ocean floor sediments, we analyzed the geochemical (major and trace element, organic carbon and hydrocarbon concentrations) and biological (benthic foraminifera) composition of 62 superficial sediment samples, from 13 to 1336 m water depth. Cluster and Factor analysis of all the variables indicate that their distribution patterns are mainly controlled by differences between the terrigenous and carbonate platforms in the SGoM. Benthic foraminiferal assemblages were abundant and diverse, and their distribution patterns are mainly determined by water depth and sedimentary environment. However, most of the abundant species are opportunistic and/or low-oxygen tolerant, and many of their tests show oil stains and infillings, characteristic of oil polluted locations, suggesting the environment has been modified by natural seepage or oil-related activities. To determine if these conditions are natural or anthropogenic in origin, pre - industrial settings should be studied. Organic carbon (Corg) content (0.6–2.9%) and total hydrocarbon concentrations (PAHs 1.0–29.5 μg kg−1) were usually higher around the oil platforms area, the natural hydrocarbon seeps (“chapopoteras”) area and offshore rivers, but there is no accumulation of oil related trace elements in these areas. However, the comparison with international sediment quality benchmarks indicates that Cd, Cr and Ni concentrations are above the threshold effect level, and also As, Ba and Cu are above the probable effect level benchmarks, which indicate that these element concentrations might be of potential ecological concern. Comprehensive studies involving different proxies, and assessing pre-industrial conditions, must be undertaken before assessing environmental health of marine benthic ecosystems.

Assessment of trace element and macronutrient accumulation capacity of two native plant species in three different Egyptian mine areas for remediation of contaminated soils

Abstract The present study aimed to compare the ability of Conyza bonariensis and Amaranthus viridis to accumulate macronutrients: nitrogen, phosphorus, potassium (NPK) and trace elements (TEs) in their underground and aboveground tissues from the soils in the mining areas. The plant parts and their soils were collected from three sites (El-Gedida mining ore site (S1), accommodation of mining workers (S2) and Harra Oasis (S3)) at Bahariya Oasis, as the Libyan part of the Western Desert in Egypt. In C. bonariensis, photosynthetic pigments and flavonoids showed a significant increase at S1 at which the shoots accumulated high amounts of TE(s) whereas, the same photosynthetic pigment fractions showed a significant increase in S3 at which the shoots accumulated the least amounts of TE(s) for A. viridis. For A. viridis flavonoids showed a significant increase at S1 (higher accumulation of TEs in shoots). C. bonariensis accumulated the higher concentrations of macronutrients in tissues than A. viridis. The translocation factors of both species varied among the TEs as well as among the different studied sites. This indicates that C. bonariensis plants tolerated toxic TE(s) stress present in the mining area which enhances the hypothesis that this plant could be used as a successful tool for phytoremediation of toxic TE(s) in polluted areas.

Trace elements in the seagrass Posidonia oceanica: Compartmentation and relationships with seawater and sediment concentrations

Seagrasses are employed to assess trace element levels in seawater and sediments; however, their capacity as bioindicators of trace elements in seawater has been recently questioned, due to the scarcity of a significant seagrass-seawater relationship. In the aim to provide an insight into trace element accumulation in the seagrass Posidonia oceanica, Cd, Co, Cr, Cu, Ni and Pb concentrations in seawater, sediments, and several seagrass compartments (adult leaf blades, intermediate leaf blades, adult leaf sheaths, juvenile leaves, orthotropic rhizomes, plagiotropic rhizomes, and roots of plagiotropic rhizomes) from the coasts of Thrace, Greece were determined. Uni- and multivariate data analyses were applied. A comparison with reported element concentrations revealed that this coastal area can be generally classified as an area of no marked Cd, Co, Cr, Cu, Ni and Pb anthropogenic enrichment. Trace elements showed a non-uniform distribution among seagrass compartments; adult leaf blades displayed the highest mean Cd and Ni concentrations, adult leaf blades, plagiotropic rhizomes and roots the highest mean Co concentrations, juvenile leaves the highest mean Cu concentration, and plagiotropic rhizomes the highest mean Cr and Pb concentrations, indicating that the accumulation varies with element, compartment and compartment age. Cd, Cr and Ni in adult leaf blades reached mean tissue-seawater accumulation factors of 103, while Co of 104, implying that this seagrass is a strong accumulator of these elements from solution. Cd, Co, Cr, and Ni concentrations in leaf compartments, particularly adult leaf blades, positively correlated with their concentrations in seawater, and Pb concentrations in plagiotropic rhizomes and roots with sediment Pb concentration. Thereby, P. oceanica could be regarded as a biondicator for Cd, Co, Cr and Ni in seawater, and for Pb in sediments. The results presented provide an insight on trace element accumulation in P. oceanica, and can be utilized for the design of biomonitoring programs.

A note on testing hypotheses concerning interaction with special reference to a graphical presentation in the space of canonical variates

Summary Results of ecological studies that involve the use of multivariate analysis of variance techniques for testing various hypotheses, interesting from the point of view of comparing the linear functions of parameters, were considered. For testing the most interesting hypotheses on a variety of interaction effects and on contrasts of class means, the application of a multivariate test statistic is recommended. Canonical variate analysis is used for graphical presentation of the results of multidimensional experiments. In this paper it is shown how a generalized form of canonical variate analysis can be useful to reveal which parametric functions of a multivariate analysis of variance model are responsible for rejecting the linear hypothesis. As an example, an analysis was made of an ecological study of trace element accumulation in plants of Italian ryegrass as a method of biomonitoring of air pollution.