Trace metals with seasonal considerations in coastal algae and molluscs from Beirut,Lebanon

Twelve species of intertidal algae and molluscs from Ras Beirut, Lebanon have been investigated for their heavy metal content. Atomic absorption spectrophotometric analysis showed that the algae and molluscs concentrated similar levels of most metals. However, of the twelve organisms, Brachydontes variabilis had the highest copper, Patella coerulea and Colpomenia sinuosa had the highest iron, and Pinctada radiata had the highest zinc values with rather elevated cadmium. Cystoseira spinosa concentrated the lowest levels of zinc, and nickel was variable in all organisms.Seasonal comparisons of metal levels were also considered in three algae and three molluscs studied previously. The only signs of seasonal variation in the algae were with nickel and iron in Halimeda tuna and lead in Pterocladia pinnata. Both cadmium and lead were generally lowest in the spring samples of the algae. Lead and nickel concentrations in the molluscs were generally highest in the summer and lowest in the spring. Slight seasonal trends were seen with lead and iron in Brachydontes variabilis and lead in Monodonta turbinata.The lack of comparison data from the Mediterranean, particularly the eastern basin, makes it essential that studies of this nature be continued.     

Trace metals in Caprella (Crustacea: Amphipoda). A new tool for monitoring pollution in coastal areas?

The main objective of the present study was to evaluate the concentration of trace metals in eight species of Caprella from sites of different degree of pollution along Southern Spain, and compare them with nine additional species of peracaridean crustaceans (5 gammarids, 3 isopods and 1 tanaid) and three molluscs. This is the first comprehensive study of trace metals in caprellids and other peracaridean crustaceans as a baseline work for future research. For most of the metals, values are higher in caprellids than in the rest of peracarideans and molluscs, as Mytilus or Patella, traditionally used as biomonitor in previous studies. Caprellids showed a significant higher range for Cr, Hg and Zn, while molluscs were better biomonitors for Pb; non-caprellid peracarids showed lower range of Fe and Ni than caprellids and molluscs. Besides the wider ranges shown by caprellids for trace metals in comparison with other invertebrates, Caprella spp. is especially abundant in intertidal and shallow waters ecosystems worldwide; this genus includes species characterised by a short generation time, and a sedentary way of life as a consequence of direct development and low capacity of swimming. Consequently, the use of Caprella spp. could be an interesting tool in monitoring programmes of heavy metal pollution.     

Interspecific differences in metal bioaccumulation and plant-water concentration ratios in five aquatic bryophytes

We studied the capacity of five species of aquatic bryophyte to accumulate metals, and the relationship between plant metal content and water composition, on the basis of 170 samples taken from 32 rivers in Galicia (NW Spain). In all cases, only the final two centimetres of the apex were analysed. Scapania undulata was the species with the highest accumulatory capacity, and Fissidens polyphyllus was that with the lowest. Fontinalis antipyretica, Rhynchostegium riparioides and Brachythecium rivulare displayed intermediate capacities for metal accumulation, but showed a broader range of variation in body concentration in comparison with similar contamination levels. This resolution capacity, together with a greater resistance to pollution and, in the study region, a wider distribution and higher abundance, suggests that the latter two species are the most useful for bioindication studies. Bioaccumulation factors were high for all metals studied, tending to increase with increasing body concentration but decreasing with increasing water concentration. The relationship between metal in plant and filtrable metal in water was low, but statistically significant for all the metals studied except Co in F. antipyretica and Cd, Pb and Co in S. undulata, F. polyphllyllus and B. rivulare. The influence of physical and chemical variables of the water on bioaccumulation was evaluated using step-wise multiple correlation analysis. Bioaccumulation is largely governed by physical and chemical factors, by the concentration of metal in the water and by the bioaccumulation factor of the bryophyte species. Sulphate concentration, pH and to a lesser extent nitrite, ammonia and FRP (filtrable reactive phosphate) appear to be the most important physical and chemical variables governing metal bioavailability.     

Accumulation of Metals and Boron in Phragmites australis Planted in Constructed Wetlands Polishing Real Electroplating Wastewater

The concentration of metals (Al, Cu, Fe, Mn, Ni, Zn) and B were determined in the above- and belowground biomass of Phragmites australis collected from the microcosm constructed wetland system used for the polishing of real electroplating wastewater. Translocation factor and bioconcentration factor were determined. Pearson correlation test was used to determine correlation between metal concentration in substrate and above- and belowground parts of Phragmites australis. The obtained results suggested that Phragmites australis did not play a major role as an accumulator of metals. It was observed also that the substrate could have exerted an effect on the translocation of Ni, Cu, Zn and Mn. The analysed concentrations of metals and B in biomass were in the range or even below the concentrations reported in the literature with the exception of Ni. The aboveground biomass was found suitable as a composting input in terms of metals concentrations.     

Effects of abiotic factors (temperature,pH, heavy metals) on activities of glycosidases in invertebrate animals

Differences in amylolytical activity have been established in the whole body of some invertebrate animals (larvae of chironomids Chironomus plumosus, pond snail Limnaea stagnalis, orb snail Planorbis corneus, faucet snail Bithynia tentaculata, and zebra mussel Dreissena polymorpha-potential objects of nutrition of fish benthophages under separate and combined actions of temperature (0, 10 or 20°C), pH (5.0, 7.4 or 8.3), and ions of heavy metals (copper, zinc at a concentration of 10 mg/l) in vitro. The most pronounced inhibitory effect on the amylolytical activity in tissues of the studied animals was produced by a combination of the low temperature, acidic pH values, and the presence of the heavy metal ions. Enzymes of chironomids were more resistant to action of the studied agents as compared with molluscs.     

Heavy metal concentrations in surficial sediments and benthic macroinvertebrates from Anzali wetland, Iran

Lead, Copper, Zinc and Manganese were measured in surficial sediments, chironomid larvae, tubificid worms and two species of bivalve molluscs (Mytilaster lineatus and Corbicula fluminalis) from the Anzali wetland, Iran.No distinct relationship was observed between heavy metal levels and percentage fine fraction in sediments. The pattern of Mn accumulation was parallel to trends of organic matter variation. There were highly significant differences between sampling sites in contents of heavy metals but no significant differences between seasons. Significant differences were found in bioaccumulation of Lead and Zinc in three size categories of chironomid larvae. Lead was higher in smaller M. lineatus, while the reverse was observed for Copper.     

Heavy metals (Cu,Zn, Pb,Cd) in sediment,zooplankton and epibenthic invertebrates from the area of the continental slope of the Banc d'Arguin (Mauritania)

The concentrations of copper, zinc, lead and cadmium in the surface sediment (upper 5 mm) were generally higher in the silt fraction than in the bulk sediment. No significant geographical trend in the metal concentrations of the surface sediments was found, nor a correlation between concentrations in bulk sediment as well as in the silt fraction and the % silt could be established. In general, the metal concentrations in both bulk sediment and silt are lower, when compared to marine environments in other climatological regions.In zooplankton, the metal concentrations were relatively high: expressed in µg g^–1 on a dry weight (D.W.) basis, they ranged from 15–90 for copper, 70–580 for zinc, 12–55 for lead and 4–10 for cadmium.In epibenthic invertebrate species, both in crustaceans and bivalve molluscs, the concentrations of copper, zinc, and lead were in the same order of magnitude as compared to corresponding species from other geographical latitudes. Cadmium concentrations were relatively low, ranging from 0.13–0.42 µg g^–1 D.W. in the bivalve molluscs Pitaria tumens and from 0.04–0.27 µg g^–1 D.W. in the shrimp Processa elegantula. Also in the crab species Ilia spinosa, Inachus sp. and Pagurus sp., the cadmium concentrations were low, varying between 0.1 and 0.2 µg g^–1 D.W.No significant relation between the metal concentration in whole-body samples and sediment (either bulk or silt) was present. Also no gradient was apparent in concentrations in organisms sampled at different depths (5 to 200 m) along two off-shore transects perpendicular to the Banc d'Arguin. Data indicated lower metal concentration in epibenthic organisms from sampling stations along a northern transect (southwest of Cap Blanc) than in organisms from the southern transect, off Cap Timiris.Evidence was obtained for a considerable atmospheric input of heavy metals, in particular zinc and lead, in a certain area along the continental slope of the Banc d'Arguin.     

The Effect of Metal Concentration in Bottom Sediments on the Accumulation of Metals by the Mytilids Crenomytilus grayanus and Modiolus kurilensis

The relationship between the concentration of Pb, Cu, Cd, Zn, and Ag in soft tissues of mytilids Crenomytilus grayanus and Modiolus kurilensis and in bottom deposits was studied to determine the potential and limitations in the use of these molluscs as bioindicators of contamination of coastal waters near Vladivostok (northwest of the Sea of Japan). It was found that the mussel C. grayanus began to accumulate Pb and Cu after certain threshold concentrations of these metals (60 and 150 g/g respectively) in fine fractions of sediments was reached. Accumulation of Pb and Cu by M. kurilensis also depended on the level of sediment contamination, but the higher initial metal content in tissues and the higher individual variability reduced the sensitivity of this species as a bioindicator. Accumulation of Cd and especially of Zn in mytilid tissues is adjusted by the organism, which restricts the opportunity of their use for tracking the anthropogenic input of bioavailable forms of these metals.     

Diversity and indicator species as measures of water pollution in a subarctic lake

Benthic invertebrates were collected from a subarctic lake during 1976 to assess the effectiveness of diversity indices and indicator species as measures of heavy metal pollution. Collections were made near an operating metal mine, where sediments were contaminated with high levels of arsenic (up to 2,500 mg/kg dry weight), mercury (500 µg/kg), lead (850 mg/kg), copper (750 mg/kg) and zinc (950 mg/kg). A total of 25 species and a diversity index of 2.4—2.9 were recorded in this heavily impacted area. Chironomids (Procladius denticulatus, Heterotrissocladius changi, Chironomus decorus) were most common in the sediments, followed in importance by molluscs (Pisidium casertanum) and oligochaetes (Lumbriculus variegatus). There were 23 and 25 species in the areas of moderate and negligible contamination, respectively. The diversity indices ranged from 2.4–2.6 and 2.4–2.8 and the main species were generally similar to those found in the heavily impacted area. While diversity indices and indicator species were therefore ineffective in monitoring metal contamination, the strong negative correlation between the concentration of metals and the abundance of benthic organisms provided a much more realistic assessment of the level of contamination.     

Algal bioassays to determine toxicity of metal mixtures

The shortcomings of many established toxicity criteria for metals have resulted from a simplification of bioassays performed with single metals. A more comprehensive approach was needed to diagnose the effects of metal mixtures on aquatic organisms. Using Chlorella, Ankistrodesmus and Scenedesmus as test organisms, we experimented on a number of factors which affected metal toxicity bioassays. These included metal interactions, algal competitions, species sensitivities, the ratio of an excess metal to other metals and nutrient levels. An alternative technique was finally established which involved an evaluation of individual assays of Chlorella and Ankistrodesmus in separate media and a tissue-metal analysis on Chlorella. Chlorella fusca, commonly found in lakes with high metal concentrations, showed high tolerance to mixed-metal solutions, while Ankistrodesmus proved to be very sensitive. By determining the maximum yield ratio between Ankistrodesmus and Chlorella (i.e. the A/Ch ratio) it was possible to compare the toxic strength of harmful metals according to an established standard curve of A/Ch ratio versus mixed-metal concentrations. The levels of tissue-metal analysed in Chlorella also gave some indication as to which metals were responsible for the toxicity.     

Trace metals in oral mucosa in relation to the lichen ruber planus pathology. A preliminary study carried out by neutron activation analysis

Lichen ruber planus, contact allergy and hypersensitivity can be linked to oral exposure to metals released from metal alloys commonly used in dentistry. In this context neutron activation analysis was developed for the microdetermination of 36 elements in oral mucosa biopsies of two patients affected by lichen ruber planus and of five subjects as control group.In order to minimise metal contamination during sample collection, biopsies were taken by laser bistoury technique and then submitted to radiochemical neutron activation analysis (RNAA).Among the metals analysed, chromium showed obvious high concentration in gingival biopsies of the two pathological subjects compared to the corresponding tissues of control group. Cobalt and nickel were also determined in higher concentrations, but only in one of the oral mucosa of the two patients.The present findings way support the hypothesis concerning a potential link of lichen ruber planus condition with the exposure to Cr, Co and Ni as released into oral cavity from prosthodontic alloys.     

Native Australian Species are Effective in Extracting Multiple Heavy Metals from Biosolids

Selecting native plant species with characteristics suitable for extraction of heavy metals may have multiple advantages over non-native plants. Six Australian perennial woody plant species and one willow were grown in a pot trial in heavy metal-contaminated biosolids and a potting mix. The plants were harvested after fourteen months and above-ground parts were analysed for heavy metal concentrations and total metal contents. All native species were capable of growing in biosolids and extracted heavy metals to varying degrees. No single species was able to accumulate heavy metals at particularly high levels and metal extraction depended upon the bioavailability of the metal in the substrate. Metal extraction efficiency was driven by biomass accumulation, with the species extracting the most metals also having the greatest biomass yield. The study demonstrated that Grevillea robusta, Acacia mearnsii, Eucalyptus polybractea, and E. cladocalyx have the greatest potential as phytoextractor species in the remediation of heavy metal-contaminated biosolids. Species survival and growth were the main determinants of metal extraction efficiency and these traits will be important for future screening of native species.     

Mobility of metals in salt marsh sediments colonised by <Emphasis Type="Italic">Spartina maritima</Emphasis> (Tagus estuary,Portugal)

Chemical associations of Zn, Pb, Cu, Co and Cd were determined using a sequential extraction procedure in sediments colonised by S. maritima in three salt marshes within the Tagus estuary: Rosário, Corroios and Pancas. Concentrations of these metals were also analysed in above- and belowground parts of Spartina maritima, as well as in sediments colonised by the plant. The highest metal concentrations in sediments were found in the marshes near the industrial and urban areas, whereas metal concentrations in plants were not significantly different among sites. This was thought to be a consequence of differences observed in metal bioavailability: Metals in Pancas, the least polluted location, were largely associated to easily accessible fractions for plant uptake, probably as a result of low organic matter content and high sandy fraction in sediments. S. maritima was able to induce the concentration of metals between its roots in the three salt marshes. The results obtained in this study indicate that S. maritima could be useful to induce phytostabilisation of metals in sediments, although the effectiveness to modify chemical associations is highly dependent on existing sediment parameters, and thus different results could be obtained depending on site characteristics. Guest editors: J. Davenport, G. Burnell, T. Cross, M. Emmerson, R. McAllen, R. Ramsay & E. Rogan Challenges to Marine Ecosystems     

Heavy metal tolerance in marine strains of Yarrowia lipolytica

Heavy metal tolerance of two marine strains of Yarrowia lipolytica was tested on solid yeast extract peptone dextrose agar plates. Based on minimum inhibitory concentration esteems, it is inferred that the two strains of Y. lipolytica were tolerant to heavy metals such as Pb(II), Cr(III), Zn(II), Cu(II), As(V), and Ni(II) ions. The impact of various heavy metal concentrations on the growth kinetics of Y. lipolytica was likewise assessed. With increased heavy metal concentration, the specific growth rate was reduced with delayed doubling time. Furthermore, biofilm development of both yeasts on the glass surfaces and in microtitre plates was assessed in presence of different heavy metals. In microtitre plates, a short lag phase of biofilm formation was noticed without the addition of heavy metals in yeast nitrogen base liquid media. A lag phase was extended over increasing metal concentrations of media. Heavy metals like Cr(VI), Cd(II), and As(V) are contrastingly influenced on biofilms’ formation of microtitre plates. Other heavy metals did not much influence on biofilms development. Thus, biofilm formation is a strategy of Y. lipolytica under stress of heavy metals has significance in bioremediation process for recovery of heavy metals from contaminated environment.

     

Bioremediation of Heavy Metals in Liquid Media Through Fungi Isolated from Contaminated Sources

Wastewater particularly from electroplating, paint, leather, metal and tanning industries contain enormous amount of heavy metals. Microorganisms including fungi have been reported to exclude heavy metals from wastewater through bioaccumulation and biosorption at low cost and in eco-friendly way. An attempt was, therefore, made to isolate fungi from sites contaminated with heavy metals for higher tolerance and removal of heavy metals from wastewater. Seventy-six fungal isolates tolerant to heavy metals like Pb, Cd, Cr and Ni were isolated from sewage, sludge and industrial effluents containing heavy metals. Four fungi (Phanerochaete chrysosporium, Aspegillus awamori, Aspergillus flavus, Trichoderma viride) also were included in this study. The majority of the fungal isolates were able to tolerate up to 400 ppm concentration of Pb, Cd, Cr and Ni. The most heavy metal tolerant fungi were studied for removal of heavy metals from liquid media at 50 ppm concentration. Results indicated removal of substantial amount of heavy metals by some of the fungi. With respect to Pb, Cd, Cr and Ni, maximum uptake of 59.67, 16.25, 0.55, and 0.55 mg/g was observed by fungi Pb3 (Aspergillus terreus), Trichoderma viride, Cr8 (Trichoderma longibrachiatum), and isolate Ni27 (A. niger) respectively. This indicated the potential of these fungi as biosorbent for removal of heavy metals from wastewater and industrial effluents containing higher concentration of heavy metals.     

The use of aquatic mosses in assessment of metal pollution: appraisal of type-specific background concentrations and inter-specific differences in metal accumulation

Tissue concentrations of Al, As, Cd, Cu, Fe, Pb and Zn were analysed from 73 river sites, including 29 unpolluted reference sites and 44 sites differently affected by land use and industrial and municipal waste waters. Concentrations were measured both in the youngest terminal parts (reflecting the most current exposure conditions) and in the whole vegetative shoot (indicating long-term exposure) of mosses. For the dominant moss species, Fontinalis antipyretica Hedw., the concentration data were stratified according to the river type (small, medium, or large peatland or moraine land rivers) and assessed for background concentrations and patterns of concentration gradients and explored possibilities for setting criteria for environmental quality standards (EQSs). Further, we analysed species-specific differences in metal concentrations of F. antipyretica, Dichelyma falcatum (Hedw.) and Hygrohypnum ochraceum (Turn. ex Wils.). The background concentrations varied more or less according to the river type; in general, peatland rivers had higher concentration than moraine land rivers. The highest metal concentrations were found in rivers contaminated by acid sulphate soils. For most metals, concentrations in D. falcatum and H. ochraceum were higher than in F. antipyretica. Prerequisites for using mosses in pollution assessment and preliminary suggestions for defining EQSs are presented.     

Invasive freshwater molluscs are consumed by native fishes in South America

The diet of seven fish species from the Río de la Plata was studied to evaluate their behaviour as predators on the invasive bivalves Corbicula fluminea and Limnoperna fortunei. It was concluded that the teleosts Pterodoras granulosus, Pimelodus maculatus, Paraloricaria vetula and Ricola macrops prey upon C. fluminea, whilst Leporinus obtusidens, Rhinodoras dorbignyi and Brochiloricaria chauliodon feed on Lim. fortunei. These fish species had altered their diets to consume large amounts of these molluscs. Three of the fishes recorded here were previously unknown to feed on molluscs. The fishes studied here prey upon molluscs that ingest trace metals with their food items, thus monitoring the situation is suggested as several of these fish species are caught for human consumption.     

High bioaccumulation of cadmium and other metals in Patagonian edible gastropods

High concentrations of metals are accumulated by edible marine resources, affecting human health. Marine gastropods have been commercially captured and consumed in Argentina for decades without official regulations or studies to guarantee their safety. In this study, metals (cadmium, aluminium, iron, zinc, copper and lead) were analysed for the first time in the edible marine gastropods Buccinanops globulosus, Adelomelon ancilla and Trophon geversianus and their surrounding sediments. Taking into account the maximum levels recommended by national and international regulations for food safety, we recommend consuming only the foot of these gastropod species. We recommend not consuming these gastropods from harbour areas due to concentrations of lead in sediments and tissues. Though the target hazard quotient (THQ) of cadmium was not high for the local community, it could be higher for other populations who consume molluscs more frequently, indicating a potential health risk of chronic exposure. Monitoring of these and other contaminants should be performed in order to ensure food safety of these marine resources.     

Effects of Cu,Pb and Zn on two Potamogeton species grown under field conditions

Two common macrophyte species, Potamogeton perfoliatus L. and Potamogeton pectinatus L. were grown for 12 weeks at shallow depths in sediments contaminated with 1250 or 2500 g Pb or Cu and/or Zn (gDW sediment)^-1. Control experiments were run at background levels of 4, 13, and 38 g Pb, Cu and Zn (gDW sediment)^-1, respectively. Effects of heavy metals on biomass production and metal uptake and distribution in plants are presented in relation to total amount and plant-available fraction of metals in the sediment.All three studied metals gave reduced biomass production, and the toxicity of the metals decreased in the order Zn>Cu>Pb. The root/shoot biomass ratio increased for P. pectinatus, but decreased for P. perfoliatus with metal treatment. The content of any single metal was higher in shoots than in roots of plants grown on sediments not contaminated with that specific metal, but addition of that metal increased the proportion in roots. The uptake by plants of any of the heavy metals increased with increased metal addition. The magnitude of the plant-available fraction of metals of untreated sediment was Zn>Cu>Pb, and increased in contaminated sediments. Addition of Cu decreased both the plant-available fraction and the total concentration of Zn in the sediment, while increased the uptake of Zn by the plants. The opposite was found for Cu when Zn was added. P. pectinatus accumulated about twice as much Cu as P. perfoliatus. On the other hand, the concentration of Pb was higher in P. perfoliatus than in P. pectinatus, and was negligible in P. pectinatus when cultivated in untreated sediments.     

Metal levels associated with tin dredging and smelting and their effect upon intertidal reef flats at ko phuket,Thailand

Summary Reef flats in the vicinity of tin dredging and smelting activities around the Laem Pan Wah peninsula, Phuket, and been quantitatively surveyed. the diversity of corals on all intertidal reefs was low (10 genera), the dominant genera being Porites, Montipora, Acropora and Platygyra. Two basic types of reef can be discerned, one dominated by Porites lutea and faviid species and the other by Montipora ramosa and Acropora aspera, reef type apparently being governed by the degree of exposure to water movement. Other natural factors affecting coral cover included freshwater run off, considerable sedimentation, and aerial exposure for 2–3 h each day. Heavy metal concentrations in invertebrate species such as the oyster Saccostrea, the bivalve Isognomon, and in the alga Padina reflected elevated metal levels at all sites when compared with controls (Figs. 8 and 9). In particular, levels of metals were considerably elevated in molluscs taken from the reef below the tin smelter. Interestingly, dead coral cover on this reef, although high, was not significantly different from values observed on reefs several kilometres away from the smelter, which were not apparently under the influence of such increased metal loads (Fig. 2).No elevation in metal concentrations in coral tissue or skeleton was evident at any site. It would appear, then, that these intertidal coral species are not obviously affected by the levels of metals discharged at the smelter site.