Metal Concentration in Oyster,Crassostrea Gigas,and Sediment in Ann-Ping Mariculture Ground,Taiwan

Abstract

This study was to assess the metal contamination in oyster tissue grown in the Ann-ping mariculture ground in Taiwan. the information generated from this work also revealed general metal pollution problem for Taiwan's oyster farmers. Oysters, Crassostrea gigas, and surficial sediments collected from ten locations in Ann-ping mariculture ground in Taiwan for metals concentration (Cu, Zn, Pd, Cd, Fe and Mn) were performed. Analytical results indicated that the yearly averaged oyster copper concentrations (μg g^?1, wet weight) in oyster soft parts from Ann-ping increased from 21.3±4.1 in 1993; 24.1±6.8 in 1994; 36.8±11.9 in 1995 to 43.9±23.1 μg g^?1, wet weight, in the 1996 raising season. the mean oyster copper concentration reached a level of 50 μg g^?1, wet weight, in December 1996. This increasing trend of metal concentration in oyster tissue indicates a potential pollution source which may pose a potential disaster as green oyster incidence, which occurred on the Charting coast in 1986, in Taiwan. Sediment samples in Ann-ping mariculture ground were also collected and examined. the seasonal variation of the copper concentration in surficial sediment from Ann-ping did not show an increasing trend as observed in oyster tissue.     

Species of Trace Metals, Organic Residues and Humic Substances in Sediments From the Taiwan Erhjin River and Coastal Areas

Total organic carbon, humic substances, and the species of trace metals (including Cu, Zn, Pb, Cd, Cr, Mn and Fe) in six and seven phases, such as bioexchangeable (P1), skeletal (carbonates, P2), easily reducible (Fe and Mn oxides, P3), moderately reducible (crystalline Mn oxides, P4), organic matters with sulphides (P5), and detritus with minerals (P6) as well as organic with humic substances (PB4) and organic residues (PB6), were analyzed in sediments from the Taiwan Erhjin coastal (including river and estuarine) area, where places we found the copper pollution. Results indicate that higher percentages of P1 and P2 for copper, zinc, lead, cadmium and manganese in samples collected in March and September of 1990 were much higher than those in P3-P6. High percentages of chromium and iron in samples respectively collected in March and September of 1990 were found in P6. for the seven phase analysis, higher percentages of copper species in PB4 and PB6 as well as iron species in PB7 were observed. On the other hand, purified humic acid with the high contents of manganese and iron in humic acid as well as purified fulvic acids were generally found at the upstream stations; and low values at coastal stations. However, extremely high copper (as high as 1750μg g^-1, dry weight in fulvic acid and 820μg g^-1 in humic acid) and lead (821μg g^-1 in humic acid) concentrations with relatively high manganese and iron concentrations were observed in humic substances from the station near the copper recycling area. Comparing the results obtained from the Antarctic Ocean sediments with those from the Taiwan Erhjin Chi coastal sediments, the human impacts on the latter are evaluated.     

Heavy Metal Concentrations in Sea Urchin Tissues From Egypt, Ireland and United Kingdom

Sea urchins (Paracentrotus lividus) were collected from the Mediterranean coast off Alexandria, Egypt and the Atlantic coast of Ireland to the west of Galway. Samples of another urchin species, Psammechinus miliaris, were collected from the entrance to Southampton Water, U.K. Both the Alexandria coast and Southampton Water receive domestic and industrial waste water inputs whilst the western Irish coast is relatively unpolluted.

Sampled animals were dissected to separate coelomic fluids, Aristotle's lantern, gonads and tissue (digestive tract plus connective tissue). the concentrations of heavy metals (cadmium, copper, lead, nickel and zinc) in the different parts were measured using flame atomic absorption spectroscopy.

Many levels of heavy metals in the different parts were similar in specimens taken across the wide range of sites and the two species. A notable exception was the high level of copper (33 μg g^-1 dry wt.) and zinc 328 μg g^-1- dry wt.) in urchin tissue from Southampton Water.

The metal concentrations in the gonads of Paracentrotus lividus are of particular interest because of human consumption of this species. the highest levels of copper (3.3-5.2 g^-1- dry wt.) and zinc (74-181 μ g^-1- dry wt.) dry wt.) in gonads were found in the samples from Egypt. Data from this study are compared with other results reported from the Mediterranean.

A simple, short term, elevated water column copper uptake experiment was undertaken with Paracentrotus lividus which showed an increase in gonad concentrations of this element.     

Speciation of organotin compounds in sediments of semi-closed areas along the Mediterranean coast of Alexandria

Organotin compounds were measured in sediments of four different semi-closed areas of the Mediterranean coast of Alexandria: the Eastern Harbour, Western Harbour, El-Max Bay, and Abu-Qir Bay. Due to the commercial trade activity inside the Western Harbour, in addition to the effect of wastes discharged from El Noubaria canal, it shows the highest concentrations of total tin (6.34 μg g^-1 dry weight), dibutyl tin (1.63 μg g^-1 wet weight), tributyl tin (0.33 μg g^-1 wet weight) and diphenyl tin (1.06 μg g^-1 wet weight) compared with other locations. The concentrations of TBT species showed the highest contents compared with DBT and DPhT compounds in all sampling areas. This trend might be due to the worldwide use of TBT not only as biocides in antifouling paints but also as preserving agents for wood, fungicides in agricultural activities, and heat and UV stabilizers of PVC, which results in a direct release of TBT into the water body, accumulation in aquatic fauna. There is also precipitation into sediments and a decrease in degradation rate into its derivatives. Variations, types, concentrations, and distribution of different organotin compounds are discussed in the areas under investigation. The study reveals a new record of organotin compounds along the Alexandria coast and makes comparisons with other surrounding areas of interest.     

Origin and Distribution of Suspended Organic Matter As Inferred From Carbon Isotope Composition in A Mediterranean Semi-Enclosed Marine System

The origin and distribution of suspended organic matter, the trophic features and the stable carbon isotopic composition of particulate organic carbon (POC) were studied monthly in a Western Mediterranean semi-enclosed basin. Sampling stations were selected as a function of wind-exposure and the degree of vegetation cover and then compared with an adjacent unvegetated site. the predominant vegetation was seagrass (Posidonia oceanica and Cymodocea nodosa) and Caulerpa prolifera. Water samples were analyzed for total suspended matter (inorganic and organic fractions), photosynthetic pigments (chlorophyll-a and phaeopigments), dissolved organic carbon, particulate organic carbon and their isotopic composition. Temperature and salinity were also measured at the same sampling sites within range of Mediterranean limits. the suspended organic matter concentration was 1.77 ± 1.55 mg l^-1; the chlorophyll-a concentration was low (0.35 ± 0.24 μg l^-1); the disolved organic carbon concentration was 2,140 ± 2,010 μg l^-1; the particulate organic carbon concentration was 212 ± 106 μg l^-1 and the isotopic composition was 18.77 ± 2.51%_°. There were significant temporal differences except for phaeopigments, POC and its POC isotopic composition, and there were no spatial differences other than for δ¹³C. This picture highlighted a general seasonal trend and trophical features similar to adjacent sea.

Spatial differences in δ¹³C showed that the source of suspended organic matter was different between stations as that between sources and wind-hydrodynamic constraints. In     

Assessment of metals in soil extracts and their uptake and movement within Tamarix nilotica at Lake Nasser banks, Egypt

This study aims to determine heavy-metal levels in soil from the banks of Lake Nasser, the ability of Tamarix nilotica to accumulate such metals from soil and hence its potential for phytoextraction. Soil and Tamarix samples were collected from the banks of four bights around Lake Nasser and analysed for Fe, Mn, Ca, Mg, Cr, Cu, Ni, Zn, Cd and Pb by atomic absorption spectrometry, whereas Na and K were measured by atomic emission spectrophotometry. Three different methods of extraction were used for the soil samples. Lead, copper and zinc were equally distributed between the exchangeable phase and Fe/Mn oxide-bound form, while other measured metals were mainly present in the Fe/Mn oxide fraction. With the exception of iron, all metals studied showed total concentrations within the geochemical background values. T. nilotica exhibited elevated concentrations of Na (36.2-48.5 mg g^-1) and K (2.74-4.33 mg g^-1) in stems, and relatively high concentrations of Pb, Cd and Co (0.39-1.03 µg g^-1, 0.24-1.3 µg g^-1 and 1.94-5.3 µg g^-1, respectively) are found in plant leaves. Bioaccumulation factors of Na and K (9.3 and 12.63, respectively) were high in T. nilotica stems. While the bioaccumulation of Pb, Cd, Co and Ni (2870.1, 2035.4, 10.5 and 5313.2, respectively) was high in plant leaves, Fe, Mn, Ca and Mg were accumulated relatively equally in plant stems and leaves. T. nilotica was found to secrete high amounts of Na, Ca and K, in addition to small amounts of all accumulated metals except Cd and Cu. These secreted metals appeared as salt crystals (67.5% Na; 25.8% Ca; 5% Mg; 1.5% K and 0.16% trace and minor elements) on the plant surface. The concentrations of all the metals studied in T. nilotica were higher than in the salt crystals. Statistical analysis of the database suggests bioaccumulation of these metals from soil to T. nilotica. This reflects the importance of using T. nilotica as a model in the phytoremediation process as an established environmental clean-up technology.     

Heavy Metals in Epiphytic Mosses: An Experience in Florence

The epiphytic moss Hypnum cupressiforme has been used for passive monitoring of airborne heavy metals pollution by vehicular traffic in the urban area of Florence. Lead, cadmium, zinc and copper were determined by differential pulse anodic stripping voltammetry (DPASV). in the summer of 1993 about 30 samples were collected from the trunks of holm oak at the same height (1 metre) from the soil. Lead contents fall within the range of 0.02-1.08 μ moles g^-1 (dry weight) and for this metal, the emission source may be attributed mainly to vehicular traffic in poorly industrialized urban areas. Some evaluations have been carried out about the employment of Zn/Pb molar ratio for characterizing airborne pollution in urban areas.     

Characterization of arsenic content in marine organisms from temperate, tropical, and polar environments

Arsenic is a widely distributed element which occurs in several chemical forms in the marine environment. Inorganic arsenic mediates the most toxic effects and predominates in sea water and sediments, while organisms generally accumulate non-toxic organic forms to concentrations probably reflecting species-specific characteristics in arsenic metabolism. This work represents an additional contribution to our knowledge on natural levels and chemical speciation of arsenic in marine organisms; basal concentrations were characterized in several species (bivalves, crustaceans, and fishes) from different environments (polar, temperate, and tropical latitudes), and results revealed an elevated variability with values ranging from less than 5 to about 200 μg g^-1. No significant effects were observed as a function of the geographical area, with the only exception of crustaceans always showing more elevated arsenic concentrations in Mediterranean species (about 45-110 μg g^-1) compared with tropical species (lower than 30 μg g^-1). Chemical speciation of arsenic was investigated in representative species from the three studied taxa; the predominance of organic forms confirmed the general tendency of marine organisms to bioaccumulate non-toxic arsenic compounds, probably resulting from a detoxification pathway.     

Heavy Metals in Moss and Bark From Urban Area of Florence: A New Cleaness Procedure for Removing Superficial Particulate Matter

Hypnum cupressiforme epiphytic moss and tree bark (elm and holm oak) samples have been collected in three sites of the city of Florence in the period 1995-1998. Lead, zinc, copper, and cadmium were determined by differential pulse anodic stripping voltammetry (DPASV) in about 200 samples collected at different heights above ground. A new clean-up procedure by nitrogen jet has been followed and its efficiency has been also verified by electron microscopy (SEM and ESEM techniques). Lead median contents in moss and bark samples fall within the ranges of 0.052-0.86 and 0.20-1.30 μmoles g^-1 (dry weight), resulting values for moss and bark are proportional to the vehicular traffic density. the increasing use of lead-free gasoline has not been followed by a decrease of lead moss concentration.     

Heavy-metal distribution and risk assessment of sediment and fish from El-Mex Bay, Alexandria, Egypt

Heavy metals are increasingly being released into natural waters from geological and anthropogenic sources. The distribution of several heavy metals (Cr, Cu, Cd, Pb, Zn, and Hg) was investigated in muscle, gill, and liver in two different fish species seasonally collected in El-Mex Bay (autumn 2004-summer 2005). In order to evaluate the pollution status of the Bay, the concentrations of the selected metals in the labile and total fractions were analysed in sediment samples collected from eight sites in El-Mex Bay during autumn 2004. Also, the Index of Geoaccumulation (I_geo) for the sediment was estimated. The total and labile fractions of the selected metals in sediment samples were 15.2 and 62.8 μg g^-1 dw for Cu, 1.8 and 5.0 μg g^-1 dw for Cd, 79.1 and 130.3 μg g^-1 dw for Zn, 0.2 and 1.2 μg g^-1 dw for Hg, 35.8 and 93.0 μg g^-1 dw for Pb, and 13.9 and 31.0 μg g^-1 dw for Cr. The concentrations of all metals were lower in flesh than those recorded in liver and gill due to their physiological roles. The metal pollution index for fish was calculated. Health hazard calculations for the contaminated sediments and fish consumption were calculated to evaluate the effect of pollution on health.     

Nitrite and Freshwater Fish

Nitrite occurs naturally in fresh waters as a result of nitrification of ammonia and denitrification of nitrate, and its concentration can be enhanced by partial oxidation of ammoniacal discharges. Nitrite is toxic to vertebrates including fish and a principal effect is the conversion of haemoglobin to methaemoglobin which is incapable of oxygen transport although there are circulatory and tissue effects as well. The toxic species is the nitrite ion (NO₂) which is believed to enter the blood via the branchial chloride/bicarbonate exchange and fish such as salmonids with high chloride uptake rates are more susceptible than those with low chloride uptake rates, for example carp. Nitrite toxicity is strongly aleviated by chloride and the concentration ratio of these ions is of great importance in assessing toxicity. Short term and long term toxicity data for a variety of fish species are presented. There are no field data on fish populations in waters where nitrite was the only pollutant. However extensive field surveys indicated that, waters with a mean chloride concentration of 25 mg l^-1 in good salmon fisheries were associated with concentrations of nitrite below 50 μg l^-1 N · NO₂, good coarse fisheries below 100 μg l^-1 N · NO₂.     

Dissolved trace-metal concentrations along the Mediterranean Sea, to the north of the Nile Delta Region, Egypt

This work focuses on four marine sites of the Mediterranean Sea, north of the Nile Delta, Egypt. Surface-water samples were collected seasonally during 2003. The aim of this study is to assess the levels of some dissolved trace metals (Fe, Mn, Zn, Cu, and Pb) in two environmental conditions. The metal concentrations in the coastal zone were in the following ranges: 11.92-30.45 μg l^-1 for Fe, 5.79-17.36 μg l^-1 for Mn, 0.87-7.80 μg l^-1 for Zn, 0.40-1.87 μg l^-1 for Cu, and 1.53-10.31 μg l^-1 for Pb. In the sites with continental water input (mixing zone), the metals were scattered in the following ranges: Fe (19.72-60.33 μg l^-1), Mn (12.63-35.60 μg l^-1), Zn (2.67-22.00), Cu (0.83-8.10 μg l^-1), and Pb (1.72-29.7 μg l^-1). The results for the metal concentrations showed a remarkable decrease in the levels of the different metals going from the estuaries and outlets into the coastal sea water. Generally, the levels of the metals in the two zones are higher than the background levels of the unpolluted area. A comparison of the trace-metal levels in the coastal zone of the Mediterranean Sea north of Nile Delta with the minimal risk concentration (reported by water-quality criteria, WQC) showed a significantly lower content at the coastal area of the Mediterranean sea of Egypt. The study also indicated that the impact of anthropogenic inputs was limited in the distribution of the metals, except that the Pb content was slightly higher in the area of the mixing zone than that reported for WQC. The relationships between the different trace-metal concentrations and the other parameters (salinity, chlorophyll a and suspended particulate matter) were discussed, and the simple regressions between them were evaluated.     

Community Experiments Using Benthic Chambers: Microbial Significance in Highly Organic Enriched Sediments

The structure of the benthic microbial loop was studied in order to understand heterotrophic pathways in the suboxic sediments of the Rapallo Harbour in autumn, 1996. Sediments were characterized by the large accumulation of organic detritus (17.2 - 21.4 μg chloroplastic pigment equivalents (CPE)g^-1; carbohydrates and proteins: 7.8-16.7 and 6.7-7.5 mg g^-1). Due to the high organic load, benthic bacteria and protozoa displayed extremely high densities (1.4 × 10⁹ cells g^-1 and 26.9 × 10⁵ cells g^-1). Meiofauna, protozoa and bacteria showed an approximate biomass ratio of 1:2:20. the presence of large amounts of organic matter appeared to determine a shift of the benthic size structure toward the increasing dominance of the smaller components of the benthic food webs. These data indicate that the sediments of the Rapallo Harbour were dominated by microbial biomasses to a larger extent than in non-food limited environments, characterized by a lower organic contamination. On the results presented in this study, the microbial dominance in highly organic enriched sediments can be explained with: (1) a reduction of the top-down control and grazing pressure of meio- and macrofauna on the microbial components; (2) the opportunistic composition and high metabolic activity of the microbial components.     

The Relationship Between Iodine, Chlorinity, Ph, Reactive Phosphate, Nitrite and Organic Matter in the Coastal Water of Alexandria

Water samples were taken from 12 stations at El-Dikheila Harbour, El-Mex Bay, Western Harbour, Qayet Bey outfall, Eastern Harbour, El-Ibrahemiya, Gleem, Sidi Bishr and Mandara, during January, April, August and November 1995. the area lies between latitude 31˚ 8' and 31˚ 17' North and longitude 29˚ 47' and 30˚ East. the annual mean of chlorinity (11.69-20.5%₀), pH (7.9-8.3), reactive phosphate (0.31-2.24 μM), nitrite (0.18-1.98 μM), oxidizable organic matter (1.97-8.95 mgO₂ 1^-1), iodide (21.14-46.74 μg 1^-1) and iodate (4.61-2.04 μg 1^-1) were measured. Iodide content in water is three times higher than iodate. Iodide is positively correlated with chlorinity (r=0.65) and iodate (r=0.45), while it is negatively correlated with nitrite (r= -0.72), oxidizable organic matter (r= -0.55) and pH (r= -0.4).     

The Distribution and Impacts of Dioxins and Polychlorinated Biphenyls in the Taiwan Er-Jen River

The distribution and impacts of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/DFs) and polychlorinated biphenyls (PCBs) in the Taiwan Er-Jen River were investigated by monitoring fish distribution and measuring PCDD/DFs and PCBs levels in sediment and fish samples. Most of the fish collected are pollution-resistant species such as Oreochromis spp, Liza macrolepsis, Channa spp and Megalops cyprinoides. the most polluted river sections are in the upstream where large amount of waste effluents from households, livestock rearing and nearby dumping sites were discharged into the river, and the lower reaches of the river where metal recovery activities including open burning of waste electrical wire/scrap occurred. Sediment samples collected near the burning site show 2,3,7,8-TCDD toxicity equivalents (TEQ) ranging from 0.014 to 14.2 ng g^-1 by PCDD/DFs and from 0.015 to 1.03 ng g^-1 by coplanar PCBs (Co-PCBs). the fish samples show TEQ ranging from 0.029 to 0.615 ng g^-1 by PCDD/DFs and from 0.012 to 0.12 ng g^-1 by Co-PCBs. Possible PCDD/DFs sources are discharged PCBs, open burning of waste wire/scrap, and pentachlorophenol. the consumption of these fish will cause an average intake of 54 pg kg^-1 d^-1 TEQ. the prevention of direct discharge of livestock and the dumping of waste effuents into River Er-Jen as well as the control of metal recovery activities appears to be the first step toward the restoration of River Er-Jen.     

Holly (Ilex Aquifolium L.) As Zinc and Cadmium Accumulative Indicator in Biogeochemical Prospecting

The results of previous investigations in mineralized and sterile areas of Tuscany (Italy) appeared to point out the special aptitude of holly (Ilex aquifolium L.) in concentrating cadmium and zinc. in the present paper this behaviour has been verified in a mineralized area of Lombardy (Northern Italy).

Samples of leaves, twigs and barks from holly trees were collected, and metal contents (Zn, Cd, and Pb) have been determined by differential pulse anodic stripping voltammetry (DPASV). for comparison, some samples of wood anemone (Anemone nemorosa L.) and soil were also analyzed.

The data obtained confirm a preferential cadmium and zinc accumulation by holly (up to 16 and 1400 μg g^-1 dry weight, respectively) also depending on different vegetal organs and vegetative stages of plants. Highest contents of lead have been recovered in the outer portion of bark.     

Hydrochemistry and dissolved nutrient flux of two small catchment rivers, south-western India

This paper deals with the water chemistry and dissolved nutrient flux of two small mountainous and heavily dammed rivers—Periyar and Chalakudy—of Kerala on the south-west coast of India. The lower reaches of these rivers are affected by sea-water ingression from the Arabian Sea during the non-monsoon season. Human interference through agriculture, urbanization, and industrialization in the lower and middle stretches of the river basins induces marked concentration variations in the hydro-chemical parameters. Except for N & P, all other chemical constituents exhibit high values during the non-monsoon season. Industrial contaminants in specific locations of the Periyar river reduce the pH to lower levels. Nutrients in the two rivers reveal marked seasonal and regional concentration variations. During the monsoon season, dissolved inorganic nitrogen (DIN) predominates over dissolved organic nitrogen (DON), but the reverse trend is observed during the non-monsoon season. The Periyar river shows higher average concentrations of DIN (monsoon 801 μg l^-1 and non-monsoon 292 μg l^-1) than Chalakudy river (monsoon 478 μg l^-1 and non-monsoon 130 μg l^-1). Dissolved inorganic phosphorus (DIP) has lower average values in the monsoon season (Periyar river, 38 μg l^-1; Chalakudy river, 42 μg l^-1) than dissolved organic phosphorus (DOP) values (Periyar river, 107 μg l^-1; Chalakudy, 62 μg l^-1). The rivers show a marked difference in nutrient flux due to its difference in water discharge/basin characteristics and point/non-point sources of contaminants. The flux rates of DIN, DIP, and DOP during the monsoon are higher than during the non-monsoon season, while those of dissolved silicon (DSi), dissolved Fe (DFe), and DON are lower. On average, the Periyar river discharges 4953 t y^-1 of DIN and 1626 t y^-1 of DON to the coastal waters, and the corres-ponding values of the Chalakudy river are 772 t y^-1 and 596 t y^-1. The Periyar and Chalakudy rivers discharge 245 t y^-1 and 70.8 t y^-1 of DIP, respectively. The total flux of DOP is considerably higher (Periyar river 703 t y^-1 and Chalakudy river 101 t y^-1). The discharge of DSi into the Periyar river (40 193 t y^-1) is nearly five times higher than that in the Chalakudy river (8275 t y^-1). The discharges of DFe through the Periyar and Chalakudy rivers are 257 t y^-1 and 36.7 t y^-1, respectively. To sum up, this study addresses the water quality and nutrient flux of two tropical rivers and discusses the impact of urbanization and industrialization on river-water quality.     

Removal of toxic chromium(VI) from aqueous solution by activated carbon using Casuarina equisetifolia

Highly activated carbon from the seed husk of Casuarina Casuarinas equisetifolia, a worldwide famous plant, have been prepared and tested for the removal of toxic Cr(VI) from its aqueous solution. The adsorbent was investigated for influences of initial chromium concentration (75, 100, 125, and 150 mg l^-1), pH, contact time, and quantity of carbon on removal of Cr(VI) from aqueous solution at room temperature (25±2 °C). The adsorption kinetic of Cr(VI) was studied, and the rates of sorption were found to conform to pseudo-second-order kinetics with a good correlation (R²≥0.99). The Langmuir and Freundlich models fit the isotherm data well. Furthermore, the Gibbs free energy was obtained for each system and was found to be-5.29 kJ mol^-1 for removal of Cr(IV). The negative value of Δ G° indicates the feasibility and spontaneous nature of adsorption. The results indicate that acidic pH (1.05) supported the adsorption of Cr(IV) on activated carbon. The maximum adsorption capacity of Cr(VI) on activated carbon was about 172.4 mg g^-1 at pH 1.05.     

Bioaccumulation and elimination of copper in the rock oyster Crassostrea cucullata

The kinetics of copper bioaccumulation in the rock oyster Crassostrea cucullata Born showed that the initial rate of uptake was directly related to metal concentration in the medium. As the accumulation in the tissues increased, the oysters remained closed and the uptake rate fell. At the end of 7 weeks, the average copper concentrations in the tissue were 60.42 g g^-1 and 63.97 g g^-1 wet weight in the 0.01 and 0.05 ppm experimental groups, respectively. The net rate of uptake ranged from 1.76 to 1.97 g g^-1 week^-1 and the rate of copper loss, measured after transferring the oysters into natural sea water, was dependent on the original cooper concentration in the soft parts. The concentration of copper in the tissues declined by 37.38 and 36.56% in the 0.01 and 0.05 ppm experimental groups, respectively. Even after a 7 week period of depuration (self-purification) there was some residual copper left in the tissue. This indicates that accumulation occurs in the tissue more rapidly than cleansing can eliminate it.     

Complexing Capacity of Thermal Waters of Montecatini Terme (Italy)

Two typical waters from thermal springs of Montecatini Terme-used as therapeutical beverages-exhibit a small complexing capacity towards Cu²⁺. By differential pulse anodic stripping voltammetry the following values were found: 0.46 μmol 1^-1 and 0.10 μmol 1^-1, respectively for Regina and Rinfresco waters.

Owing to the presence of a small amount of complexed copper in the original samples, the complexing capacity has to be regarded as residual capacity. In bottled waters from the same springs no complexing capacity was detected. Values of formation constants for copper complexes are given. No residual complexing capacity for Cu²⁺ was displayed for Tamerici and Tettuccio thermal waters.