Effects of heavy metals on sea urchin embryo development. Part 2. Interactive toxic effects of heavy metals in synthetic mine effluents

Interactive toxic effects between heavy metals were investigated using a sea urchin (Anthocidaris crassispina) bioassay. An effluent from an abandoned mine showed significant inhibitory effects on embryo development as well as producing specific malformations. The effects on the embryos were reproduced by synthetic polluted seawater consisting of eight metals (manganese, lead, cadmium, nickel, zinc, chromium, iron, and copper) at the concentrations detected in the mine effluent. This indicated that the heavy metals were responsible for the effects observed. Five heavy metals were ranked in decreasing order of toxicity as follows: Cu>Zn>Pb>Fe>Mn. Among these, zinc and manganese could cause malformation of the embryos. From bioassay results using 27 combinations of heavy metals, 16 combinations including zinc could produce specific malformations, such as radialized, exo-gastrulal, and spaceship Apollo-like gastrulal embryos. Zinc was one of the elements responsible for causing malformations and its effects were intensified by the presence of the other metals, such as manganese, lead, iron, and copper.     

Comparison of heavy metal toxicity in life stages (spermiotoxicity, egg toxicity, embryotoxicity and larval toxicity) of Hydroides elegans

A toxicity test was developed to examine the effects of heavy metal contaminants on the early life stages of the marine polychaete. We have studied the effects of metals on fertilization and early development of marine polychaete Hydroides elegans. These heavy metals have often been found in polluted ground and water near industrial discharges, and have therefore been detected from time to time in the food chain. They have been reported to alter various reproduction functions in various animals including marine populations. The toxic effect of mercury, cadmium, lead, nickel and zinc on sperm viability, fertilization, embryogenesis and larvae of H. elegans was examined. We observed that the rate of fertilization decreased when the sperm was incubated with heavy metals. Treatment of eggs with each metal did not prevent fertilization, but delayed or blocked the first mitotic divisions, and altered early embryonic development. All these effects were observed at relatively high concentrations. However, bio-accumulation in sediments and aquatic organisms have been reported. Polychaete eggs may then be in contact with very high concentrations of these heavy metals in areas where these metals are not handled or stocked properly, and then develop into abnormal embryos. In addition to bivalves and sea-urchins, polychaete embryos can provide biological criteria for seawater quality standards taking into account the sensitivity of the invertebrates and their contribution in detection of harmful chemicals with no marked effect on the species. Our results indicate that the early development of H. elegans is highly sensitive to heavy metals and this polychaete can be routinely employed as a test organism for ecotoxicity bioassays in tropical and subtropical regions.     

Performance evaluation of intermediate cover soil barrier for removal of heavy metals in landfill leachate

This pilot-scale study evaluated the use of intermediate cover soil barriers for removing heavy metals in leachate generated from test cells for co-disposed fly ash from municipal solid waste incinerators, ash melting plants, and shredder residue. Cover soil barriers were mixtures of Andisol (volcanic ash soil), waste iron powder, (grinder dust waste from iron foundries), and slag fragments. The cover soil barriers were installed in the test cells' bottom layer. Sorption/desorption is an important process in cover soil bottom barrier for removal of heavy metals in landfill leachate. Salt concentrations such as those of Na, K, and Ca in leachate were extremely high (often greater than 30 gL(-1)) because of high salt content in fly ash from ash melting plants. Concentrations of all heavy metals (nickel, manganese, copper, zinc, lead, and cadmium) in test cell leachates with a cover soil barrier were lower than those of the test cell without a cover soil barrier and were mostly below the discharge limit, probably because of dilution caused by the amount of leachate and heavy metal removal by the cover soil barrier. The cover soil barriers' heavy metal removal efficiency was calculated. About 50% of copper, nickel, and manganese were removed. About 20% of the zinc and boron were removed, but lead and cadmium were removed only slightly. Based on results of calculation of the Langelier saturation index and analyses of core samples, the reactivity of the cover soil barrier apparently decreases because of calcium carbonate precipitation on the cover soil barriers' surfaces.     

Acute toxicity of heavy metals towards freshwater ciliated protists

The acute toxicity of five heavy metals to four species of freshwater ciliates (Colpidium colpoda, Dexiotricha granulosa, Euplotes aediculatus, and Halteria grandinella) was examined in laboratory tests. After exposing the ciliates to soluble compound of cadmium, copper, chromium, lead, and nickel at several selected concentrations, the mortality rate was registered and the LC50 values (with 95% confidence intervals) were calculated. Large differences appeared in sensitivities of the four species to the metals. H. grandinella showed the highest sensitivity for cadmium (0.07 mg l(-1), LC50) and lead (0.12 mg l(-1), LC50), whilst E. aediculatus showed the highest sensitivity for nickel (0.03 mg l(-1), LC50). The comparison with data obtained with other species indicate that Halteria grandinella and Euplotes aediculatus are excellent and convenient bioindicator for evaluating the toxicity of waters and wastewaters polluted by heavy metals. The short time (24 h) and simplicity of the test procedure enable this test to be used in laboratory studies.     

Heavy metals in Ras Beirut prawns and sea urchin eggs.

Whole samples of Palaemon elegans Rathke, 1837 and eggs of Paracentrotus lividus Lamarck, 1816 were collected on the coast of Ras Beirut, Lebanon in the summer and fall of 1977 and the spring of 1978. All were analysed for lead, cadmium, copper and other heavy metals. Lead concentrations in both the prawns and sea urchin eggs appeared to be highest in the summer and lowest in the spring, whereas cadmium was low in all seasons with only a few elevated readings. The strongest tendency towards seasonal variation was seen in the copper levels of the prawns, which were high in summer, much lower in fall, and then high again in spring. Results of the analyses for nickel, iron, zinc and chromium are also discussed. Of the various possible sources of heavy metals in the Ras Beirut coastal area, untreated sewage, pesticide residues, and automobile exhaust are the most important.     

Compartmentation of metals in foliage of Populus tremula grown on soils with mixed contamination. II. Zinc binding inside leaf cell organelles

The phytoextraction potential of plants for removing heavy metals from polluted soils is determined by their capacity to store contaminants in aboveground organs and complex them safely. In this study, the metal compartmentation, elemental composition of zinc deposits and zinc complexation within leaves from poplars grown on soil with mixed metal contamination was analysed combining several histochemical and microanalytical approaches. Zinc was the only heavy metal detected and was stored in several organelles in the form of globoid deposits showing β-metachromasy. It was associated to oxygen anions and different cations, noteworthy phosphorous. The deposit structure, elemental composition and element ratios indicated that zinc was chelated by phytic acid ligands. Maturation processes in vacuolar vs. cytoplasmic deposits were suggested by differences in size and amounts of complexed zinc. Hence, zinc complexation by phytate contributed to metal detoxification and accumulation in foliage but could not prevent toxicity reactions therein.     

Metal bioaccumulation in the greater white-toothed shrew, Crocidura russula, inhabiting an abandoned pyrite mine site

Hepatic and renal concentrations of iron, magnesium, zinc, lead, copper, manganese, mercury, cadmium, molybdenum, chromium, and nickel were quantified in shrews (Crocidura russula) inhabiting a pyrite mine site in Portugal. Several morphological parameters (body weight, residual index, and relative weights) were also examined to clarify the physiological effects of pollution. Shrews from the mine showed increased bioavailability of Fe, Pb, Hg, Cd, Mo, and Ni in comparison with reference specimens. Adult shrews had the highest Cd levels while Cr and Ni concentrations diminished. Intersexual differences were found for Mo and Ni. As a consequence of metal pollution, the relative hepatic weight was higher in shrews from the mine site when compared with reference specimens. These data indicate that C. russula is a good bioindicator of metal pollution. We also evaluated the toxic effects of Pb, Hg, Cd, and Ni, because several shrews from the polluted site showed high concentrations of these metals. To approximate at the real biological impact of abandoned mines, after this first step it is necessary to associate the bioaccumulation levels and morphological effects with other physiological, ecological and genetical biomarkers.     

Effect of overlying water pH, dissolved oxygen, salinity and sediment disturbances on metal release and sequestration from metal contaminated marine sediments

Experiments were undertaken to examine the key variables affecting metal release and sequestration processes in marine sediments with metal concentrations in sediments reaching up to 86, 240, 700, and 3000 mg kg(-1) (dry weight) for Cd, Cu, Pb and Zn, respectively. The metal release and sequestration rates were affected to a much greater extent by changes in overlying water pH (5.5-8.0) and sediment disturbance (by physical mixing) than by changes in dissolved oxygen concentration (3-8 mg l(-1)) or salinity (15-45 practical salinity units). The physical disturbance of sediments was also found to release metals more rapidly than biological disturbance (bioturbation). The rate of oxidative precipitation of released iron and manganese increased as pH decreased and appeared to greatly influence the sequestration rate of released lead and zinc. Released metals were sequestered less rapidly in waters with lower dissolved oxygen concentrations. Sediments bioturbated by the benthic bivalve Tellina deltoidalis caused metal release from the pore waters and higher concentrations of iron and manganese in overlying waters than non-bioturbated sediments. During 21-day sediment exposures, T. deltoidalis accumulated significantly higher tissue concentrations of cadmium, lead and zinc from the metal contaminated sediments compared to controls. This study suggests that despite the fact that lead and zinc were most likely bound as sulfide phases in deeper sediments, the metals maintain their bioavailability because of the continued cycling between pore waters and surface sediments due to physical mixing and bioturbation.     

Application of principal component analysis for the estimation of source of heavy metal contamination in surface sediments from the Rybnik Reservoir

The concentrations of metals, loss of ignition and nutrient (N, P) were determined in the bottom sediments of the Rybnik Reservoir (southern Poland). The mean concentrations of the metals in the bottom sediments were: Cd 25.8 microgram/g, Cu 451.7 microgram/g, Zn 1583.4 microgram/g, Ni 71.1 microgram/g, Pb 118.6 microgram/g, Cr 129.8 microgram/g, Fe 38782 microgram/g and Mn 2018.7 microgram/g. The bottom sediments are very heavily loaded with zinc, manganese, copper, nickel, phosphorus and lead (percentage enrichment factor), and cadmium, phosphorus and zinc (index of geoaccumulation). The increase of cadmium, lead, nickel and zinc concentrations was connected with the inflow of the contaminated water of the river Ruda and long-range transport. The contamination of the reservoir with copper and manganese resulted mainly from atmospheric precipitation. The variability of the bottom sediment loading with metals during the investigations was affected in the first place by changes in the concentration of iron, but also those elements whose concentrations in the bottom sediment were elevated compared to the concentrations in shale--cadmium, nickel and lead.     

Body metal concentrations and glycogen reserves in earthworms (Dendrobaena octaedra) from contaminated and uncontaminated forest soil

Stress originating from toxicants such as heavy metals can induce compensatory changes in the energy metabolism of organisms due to increased energy expenses associated with detoxification and excretion processes. These energy expenses may be reflected in the available energy reserves such as glycogen. In a field study the earthworm, Dendrobaena octaedra, was collected from polluted areas, and from unpolluted reference areas. If present in the environment, cadmium, lead and copper accumulated to high concentrations in D. octaedra. In contrast, other toxic metals such as aluminium, nickel and zinc appeared to be regulated and kept at low internal concentrations compared to soil concentrations. Lead, cadmium and copper accumulation did not correlate with glycogen reserves of individual worms. In contrast, aluminium, nickel and zinc were negatively correlated with glycogen reserves. These results suggest that coping with different metals in earthworms is associated with differential energy demands depending on the associated detoxification strategy.     

Zinc effect on the sea urchin Paracentrotus lividus immunological competence

Pollution by heavy metals has become one of the most important problems in marine coastal areas as a consequence of anthropogenic inputs. Among metal contaminants, zinc, being considered not very toxic, is sometimes released into the sea in appreciable quantities and its concentration is loosely regulated.In this work we analyzed the effects of a high zinc concentration on the sea urchin Paracentrotus lividus immune system. In particular, after 24 h of zinc treatment, we evaluated coelomocytes morphology and composition as well as the zinc influence on some humoral parameters such as hemolysis, lysozyme-like activity and antibacterial activity on Vibrio alginolyticus. Our results evidenced that the presence of zinc affected both cellular and acellular components of the sea urchin immune system. The P. lividus coelomocytes changed in morphology and number; moreover, the amebocytes changed from a petaloid to a filipodial-like shape and the red spherula cells increased in number. Among the considered humoral effectors lysozyme-like activity and antibacterial activity on V. alginolyticus decreased in short-term to zinc treatment. The modifications in the sea urchin immunological competence might give an early indication of disease susceptibility thus suggesting to consider the examined defence mechanisms as potential biological indicators of metal pollution.     

Contributions of heavy metals from municipal runoff to the sediments of Lake Pontchartrain, Louisiana

A study was conducted to determine the distribution and sources of heavy metal pollutants in the sediments of Lake Pontchartrain. Sediment samples were collected from the northern and southern shorelines and analyzed for heavy metals by atomic absorption spectrometry. The heavy metals of interest were barium, copper, nickel, lead, and zinc. The concentrations of these metals indicate that the principal source of heavy metal pollution is associated with urban stormwater runoff and municipal discharges.     

Enhanced removal of heavy metals in primary treatment using coagulation and flocculation.

The goal of this study was to determine the removal efficiencies of chromium, copper, lead, nickel, and zinc from raw wastewater by chemically enhanced primary treatment (CEPT) and to attain a total suspended solids removal goal of 80%. Operating parameters and chemical doses were optimized by bench-scale tests. Locally obtained raw wastewater samples were spiked with heavy metal solutions to obtain representative concentrations of metals in wastewater. Jar tests were conducted to compare the metals removal efficiencies of the chemical treatment options using ferric chloride, alum, and anionic polymer. The results obtained were compared with those from other studies. It was concluded that CEPT using ferric chloride and anionic polymer is more effective than CEPT using alum for metals removal. The CEPT dosing of 40 mg/L ferric chloride and 0.5 mg/L polymer enhanced heavy metals removal efficiencies by over 200% for chromium, copper, zinc, and nickel and 475% for lead, compared with traditional primary treatment. Efficient metals capture during CEPT can result in increased allowable headworks loadings or lower metal levels in the outfall.     

The effect of turbation on zinc relocation in a vertical floodplain soil profile

Turbation is hypothesized to affect the redistribution of heavy metals in polluted floodplain soils by effects on mobility. This hypothesis was tested in microcosms by turbation of zinc-spiked sediment top layers. Manual turbation caused a fast decrease of the zinc content in the upper 15 cm of the soil, even though turbation was only applied to the upper two centimetres. It was especially zinc attached to colloid and organic matter particles that was redistributed from the top layer. Percolation processes resulted in the attached zinc being drained to depths of more than 15 cm. The decrease in zinc content of the topsoil was even stronger in combination with inundation. No indications were found for the redistribution of zinc as a result of an increase of the extractability with 0.01 M CaCl2 or changes in pH. The findings suggest that mechanical turbation and bioturbation may redistribute heavy metals from topsoils in polluted floodplains just after inundation as observed in these turbation experiments.     

Heavy metal speciation and mobility assessment of arid soils in the vicinity of Al Ain landfill, United Arab Emirates

Sixty-four surface soil samples taken in the vicinity of Al Ain landfill were analysed for cadmium, chromium, copper, nickel, lead and zinc by inductively coupled plasma spectroscopy. Extraction techniques were used to establish the association of the total concentrations of the six metals in the soil samples with their contents in the exchangeable, carbonate, iron/manganese oxides, and residual fractions. In the investigated soils, the recorded concentrations were as follows: 0.043 mg kg^-1 for cadmium, 19.1 mg kg^-1 for chromium, 53.3 mg kg^-1 for copper, 60 mg kg^-1 for nickel, 13.7 mg kg^-1 for lead, and 117 mg kg^-1 for zinc. Cadmium, chromium, nickel, lead and zinc concentrations in the investigated soil samples reflect the natural background values in shale, whereas copper is slightly enriched. I-geo (geoaccumulation index) values of the metals in the soils under study indicate that they are uncontaminated with cadmium, chromium, nickel, lead and zinc, but contaminated to moderately contaminated with copper. Heavy metal contents in the sediments were found to be significantly influenced by different physico-chemical parameters. The effect of these parameters can be arranged in the following order: clay fraction > carbonate fraction > silt fraction > organic matter fractions. A sequential extraction procedure showed that the total concentrations of the heavy metals are largely bound to the residual phase (retained 71.4% of cadmium, 77.8% of chromium, 75% of copper, 47% of nickel, 62.8% of lead, and 75.8% of zinc). A likely sequence of mobility in the investigated soils is as follows: chromium > lead > nickel > cadmium > zinc > copper.     

Tidal salt marsh sediment in California, USA. Part 2: occurrence and anthropogenic input of trace metals

Surface sediment samples (0–5 cm) from 5 tidal salt marshes along the coast in California, USA were analyzed to investigate the occurrence and anthropogenic input of trace metals. Among study areas, Stege Marsh located in the central San Francisco Bay was the most contaminated marsh. Concentrations of metals in Stege Marsh sediments were higher than San Francisco Bay ambient levels. Zinc (55.3–744 μg g⁻¹) was the most abundant trace metal and was followed by lead (26.6–273 μg g⁻¹). Aluminum normalized enrichment factors revealed that lead was the most anthropogenically impacted metal in all marshes. Enrichment factors of lead in Stege Marsh ranged from 8 to 49 (median = 16). Sediments from reference marshes also had high enrichment factors (2–8) for lead, indicating that lead contamination is ubiquitous, possibly due to continuous input from atmospherically transported lead that was previously used as a gasoline additive. Copper, silver, and zinc in Stege Marsh were also enriched by anthropogenic input. Though nickel concentrations in Stege Marsh and reference marshes exceeded sediment quality guidelines, enrichment factors indicated nickel from anthropogenic input was negligible. Presence of nickel-rich source rock such as serpentinite in the San Francisco Bay watershed can explain high levels of nickel in this area. Coefficients of variation were significantly different between anthropogenically impacted and non-impacted metals and might be used as a less conservative indicator for anthropogenic input of metals when enrichment factors are not available.     

Biomonitoring of air quality employing in situ Ramalina celastri in Argentina

The lichen Ramalina celastri was employed as an in situ biomonitor for the study of air quality and heavy metal distribution in the central region of the Argentine Republic. The thallus content of copper, iron, manganese, cobalt, zinc, nickel and lead was determined by atomic absorption spectrophotometry. Pigments, hydroperoxy conjugated dienes, malondialdehyde and sulfur were also measured. Some of these parameters were used to calculate a pollution index. Geographical distribution patterns were obtained for the different metals by mapping. Thus, zinc shows high levels in industrial and agricultural zones. The highest nickel values were found in urban-industrial zones located at the centre and south of the study area. The same was observed for sulfur. The pollution index distribution map showed that major physiological damage in the biomonitor was found in central and southeastern areas that coincide with Cordoba City and agricultural zones. So, the effect would seem to be related to urban activities and the use of pesticides.     

Compartmentation of metals in foliage of Populus tremula grown on soils with mixed contamination. I. From the tree crown to leaf cell level

In order to achieve efficient phytoextraction of heavy metals using trees, the metal allocation to aboveground tissues needs to be characterised. In his study, the distribution of heavy metals, macro- and micronutrients and the metal micro-localisation as a function of the leaf position and heavy metal treatment were analysed in poplars grown on soil with mixed metal contamination. Zinc was the most abundant contaminant in both soil and foliage and, together with cadmium, was preferentially accumulated in older foliage whereas excess copper and lead were not translocated. Changes in other element concentrations indicated an acceleration in aging as a consequence of the metal treatment. Excess zinc was irregularly accumulated inside leaf tissues, tended to saturate the veins and was more frequently stored in cell symplast than apoplast. Storage compartments including metabolically safe and sensitive subcellular sites resulted in sizable metal accumulation as well as stress reactions.     

The effect of hydrological factors on trace metal contamination in the river Tawe, South Wales

The concentrations of nickel, copper, iron, chromium, lead, cadmium, manganese and zinc have been studied in a small river in South Wales. The river drains the contaminated industrial wasteland of the Lower Swansea Valley which is currently undergoing redevelopment and landscaping activity. The high trace metal levels found in the river waters result from weathering and erosion of this waste material, as well as from two industrial point sources of nickel, and iron and chromium. Hydrological factors found to be of importance in determining current spatial and temporal patterns of contamination included: (1) the river's available dilution at any one time, (2) antecedent river flow conditions, (3) river water pH and (4) the prevailing runoff processes in operation at any one time. The metals are present mostly in their dissolved state (i.e. > 70%), with the exception of iron and chromium which are present mostly as particulates (i.e > 80%).     

Relationship between blood concentrations of heavy metals and cytogenetic and endocrine parameters among subjects involved in cleaning coastal areas affected by the 'Prestige' tanker oil spill

The sinking of the 'Prestige' oil tanker in front of the Galician coast (NW of Spain) in November 2002 offered a unique opportunity to analyze intermediate cytogenetic and endocrine effects among people exposed to the complex mixture of substances that oil constitutes, including several toxic heavy metals. In this work we evaluated the relationship between exposure to heavy metals (blood concentrations of aluminium, cadmium, nickel, lead and zinc) and genotoxic parameters (sister chromatid exchanges, micronucleus test and comet assay) or endocrine parameters (plasmatic concentrations of prolactin and cortisol) in subjects exposed to 'Prestige' oil during cleaning tasks developed after the spillage. Concentrations of lead were significantly related to the comet assay even after adjusting by age, sex and smoking. Cortisol concentrations were significantly influenced by aluminium, nickel (both, inversely) and cadmium (positively). Women had clearly higher concentrations of prolactin and cortisol, even when adjusting by age, smoking, cadmium, aluminium or nickel. Plasmatic cortisol was jointly influenced by gender, smoking and aluminium or nickel (all p<0.05). In women there was a strong relationship between concentrations of cadmium and prolactin (beta=0.37, p=0.031). When the effects of cadmium, aluminium and nickel on cortisol were simultaneously assessed, only the latter two metals remained statistically significant. Among parameters analysed, cortisol appeared to be the most sensitive to the effects of metal exposure. Plasma levels of cortisol deserve further evaluation as a potentially relevant biomarker to assess the effects of exposure to heavy metals.