Kinetic measurements of metal accumulation in two marine macroalgae

 We measured the uptake kinetics of four metals (Cd, Cr, Se and Zn) in two marine macroalgae (the green alga Ulva lactuca and the red alga Gracilaria blodgettii). Metal uptake generally displayed a linear pattern with increasing exposure time. With the exception of Cr, which exhibited comparable uptake rate constants at different concentrations, uptake rate constants of Cd, Se and Zn decreased with increasing metal concentration, indicating that the seaweeds had a higher relative uptake at lower metal concentration. Uptake of Cd and Zn was higher in U. lactuca than in G. blodgettii, whereas uptake of Cr and Se was comparable between the two species. Only Cd and Zn uptake in U. lactuca was significantly inhibited by dark exposure. A decrease in salinity from 28 to 10‰ enhanced the uptake of Cd, Cr, Se and Zn in U. lactuca 1.9-, 3.0-, 3.6-, and 1.9-fold, respectively. In G. blodgettii, Cd uptake increased twofold when salinity was decreased from 28 to 10‰, whereas uptake of Cr and Zn was not significantly affected by salinity change. The calculated depuration rate constants of metals in U. lactuca were 0.01 d⁻¹ for Cd, 0.05 to 0.08 d⁻¹ for Cr, 0.14 to 0.16 d⁻¹ for Se, and 0.12 to 0.15 d⁻¹ for Zn, and were relatively independent of the metal body burden in the algae. The predicted bioconcentration factor was 3 × 10⁴ for Cd, 2 × 10³ for Cr, 40 to 150 for Se, and 1 to 2 × 10⁴ for Zn in U. lactuca. Our kinetic study suggested that U. lactuca would be a good biomonitor of Cr and Zn contamination in coastal waters. Received: 14 September 1998 / Accepted: 29 May 1999     

Uptake,distribution and loss of Cr in the crab Xantho hydrophilus

Uptake of ⁵¹Cr(III) is faster than uptake of ⁵¹Cr(VI), but it occurs mainly on the surface of the animals. Steady state is attained after 28 d. The resulting concentration factor is about 200. Although the uptake of ⁵¹Cr(VI) is slower, it is more intensively distributed into the organs and tissues of the animals. Steady state was not attained during the experiments (35 d); the highest concentration factor reached was about 10. The uptake of both ⁵¹Cr(III) and ⁵¹Cr(VI) seems to be passive. For both chemical forms of chromium, the loss rate is inversely proportional to the exposure time. When the uptake lasted longer, owing to the distribution of Cr(VI) into the organs and tissues, the loss rate of Cr(III) is somewhat faster relative to the loss rate of ⁵¹Cr(VI). The opposite is the case when the uptake of both forms lasts only two days. On the basis of the distribution and loss experiments, we argue that hexavalent chromium in living organisms is reduced to the trivalent form and then complexed with organic molecules.     

Effects of Cadmium on Nutrient Uptake and Translocation by Indian Mustard

Plants that hyperaccumulate metals are ideal subjects for studying the mechanisms of metal and mineral nutrient uptake in the plant kingdom. Indian Mustard (Brassica juncea) has been shown to accumulate moderate levels of Cd, Pb, Cr, Ni, Zn, and Cu. In this experiment, 10 levels of Cd concentration treatments were imposed by adding 10–190 mg Cd kg^–1 to the soils as cadmium nitrate [Cd(NO₃)₂]. The effect of Cd on phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and the micronutrients iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) in B. juncea was studied. Plant growth was affected negatively by Cd, root biomass decreased significantly at 170 mg Cd kg^–1 dry weight soils treatment. Cadmium accumulation both in shoots and roots increased with increasing soil Cd treatments. The highest concentration of Cd was up to 300 mg kg^–1 d.w. in the roots and 160 mg kg^–1 d.w. in the shoots. The nutrients mainly affected by Cd were P, K, Ca, Fe, and Zn in the roots, and P, K, Ca, and Cu in the shoots. K and P concentrations in roots increased significantly when Cd was added at 170 mg kg^–1, and this was almost the same level at which root growth was inhibited. Zn concentrations in roots decreased significantly when added Cd concentration was increased from 50 to 110 mg kg^–1, then remained constant with Cd treatments from 110 to 190 mg kg^–1. However, Zn concentrations in the shoots seemed less affected by Cd. It is possible that Zn uptake was affected by the Cd but not the translocation of Zn within the plant. Ca and Mg accumulation in roots and shoots showed similar trends. This result indicates that Ca and Mg uptake is a non-specific process.     

Flux of radioactive cadmium through the sea-skater Halobates (Heteroptera: Gerridae)

Uptake of ¹⁰⁹Cd in freshly caught sea-skaters Halobates nereis and H. flaviventris was measured under the influence of abiotic parameters as salinity and stable Cd concentration. After 6 d of accumulation a concentration factor of 8 over the seawater level was reached with no indication for an equilibration. The calculated biological half-life of ¹⁰⁹Cd amounted to 9.3 d. Cadmium uptake from food (wingless Drosophila sp. flies reared on cadmium enriched agar) can be considerable. A large pond-skater Limnogonus fossarum, measured for comparative purposes, accumulated cadmium, but at a much lower rate. The results are discussed with respect to observed natural cadmium concentrations in open ocean sea-skater populations.     

Effects of environmental factors on radiocadmium uptake by four species of marine bivalves

Temperature, salinity, bottom-sediment type, and zinc concentration all influenced Cd uptake by 4 marine bivalves (Mya arenaria, Mytilus edulis, Mulinia lateralis and Nucula proxima) in short-term static assay systems using ¹⁰⁹Cd as a tracer. The experimental system consisted of aquaria containing 20 l of seawater maintained under controlled light and temperature conditions. The water contained either 5 or 20 g/l Cd and tracer. Distribution and kinetics of the metal were monitored in the water column and organisms. The results demonstrate that Cd uptake rates differed widely among the organisms tested. An increase in temperature increased Cd uptake rate by all test organisms. A decrease in salinity increased Cd uptake by all organisms tested. The presence of bottom sediment depresses Cd accumulation in some benthic animals. Zinc in concentrations of 0.5 mg/l substantially decreased Cd uptake by Mytilus edulis and Mulinia lateralis. It is suggested that all important species and environmental variables be considered when studying heavy-metal uptake by marine organisms or when establishing water-quality criteria.     

Assessment of relative bioavailability of heavy metals in soil using in vivo mouse model and its implication for risk assessment compared with bioaccessibility using in vitro assay

There is limited study to simultaneously determine the relative bioavailability of heavy metals such as Cd, Pb, Cu, Cr(VI), and Ni in soil samples. In the present study, the bioaccessibility of heavy metals using in vitro assay was compared with the relative bioavailability of heavy metals using in vivo mouse model. The bioaccessibility of heavy metals ranged from 9.05 ± 0.97 % (Cr) to 42.8 ± 3.52 % (Cd). The uptake profile of heavy metals in soil and solution samples in mouse revealed that the uptake kinetics could be fitted to a two-compartment model. The relative bioavailability of heavy meals ranged from 34.8 ± 7.0 % (Ni) to 131 ± 20.3 % (Cu). Poor correlation between bioaccessibility and relative bioavailability of heavy metals was observed (r ² = 0.11, p > 0.05). The relative bioavailability of heavy metals was significantly higher than the bioaccessibility of heavy metals (p < 0.05). The present study indicated that the in vitro digestion method should be carefully employed in risk assessment.     

Ecological and human health risks from metal(loid)s in peri-urban soil in Nanjing,China

In order to investigate the ecological and human health risks of metal(loid)s (Cu, Pb, Zn, Ni, Cd, Mn, Cr, and As) in peri-urban soils, 43 surface soil samples were collected from the peri-urban area around Nanjing, a megacity in China. The average contents were 1.19, 67.8, 37.6, 105, 167, 44.6, 722, and 50.8 mg kg^?1 for Cd, Cr, Ni, Pb, Zn, Cu, Mn, and As, respectively. A significant positive correlation was found between Cu, Pb, Zn, Cd, Mn, and As (p < 0.01), and Cr had a significant positive correlation with Ni (p < 0.01). Geoaccumulation indices indicate the presence of Cd and As contamination in all of the peri-urban soil samples. Potential ecological risk indices show that the metal(loid)s in the soil could result in higher ecological risks. Cd is the main contributor to the risk, followed by As. The levels of Cu, Pb, Zn, Cd, Mn, and As in stomach and intestinal phases show a positive linear correlation with their total contents. Mn, Zn, Ni, Cd, and Pb in stomach phase showed higher bioaccessibility, while in intestinal phase, Cu, Cr, and As had the higher bioaccessibility. The carcinogenic risk in children and adults posed by As, Pb, and Cr via ingestion was deemed acceptable. The non-carcinogenic risks posed by these metal(loid)s via ingestion to children are higher than to adults and mainly result from As.     

Etude de l'absorption,de la concentration et du métabolisme du strontium 85 chez le crustacé décapode Caricinus maenas

Strontium is absorbed and retained by Carcinus maenas L. The variations of the specific activity rates due to the retention of ⁸⁵Sr have been studied for the whole animals as a function of its size and the activity of the contaminating water. The same study has been carried out as a function of the stages of the intermoult cycles for both the whole animal and the organs and tissues likely to affect the uptake, storing, or further metabolism of strontium in the hepatopancreas, hypoderm, blood, gills, muscle and exoskeleton. On the basis of the results, assumptions are made on the respective part played by these organs or tissues in the processes studied.     

Comparison of the bioavailability of Cr and Fe bound with natural colloids of different origins and sizes to two marine bivalves

Recent studies have demonstrated the significant role of colloidal microparticles or macromolecules in the biogeochemical cycling of trace metals in aquatic environments. In this study, the influences of different colloidal organic carbon (COC) concentrations, colloidal sizes and colloidal origins (estuarine vs coastal) on the bioavailability of two trace metals (Cr and Fe) to the green mussel Perna viridis and the clam Ruditapes philippinarum were examined under laboratory conditions. Natural colloids were isolated by cross-flow ultrafiltration and were radiclabeled with ⁵⁹Fe and ⁵¹Cr before being exposed to the mussels and clams. The uptake of colloid-bound Cr and Fe was compared with the uptake of low molecular weight complexed metals (<1 kDa). Both natural colloid-bound Cr and Fe were bioavailable to the green mussels and clams. The uptake of both colloidal Cr and Fe by the two bivalves was much higher than that of their counterparts in a low molecular weight fraction, implying that colloidal binding enhanced considerably the bioavailability of Cr and Fe to the bivalves. The magnitude to which Cr uptake was enhanced, due to its binding with colloids, was much greater than that of Fe. There was no significant difference in the measured dry weight concentration factor of the metals between the two COC concentrations. Similarly, the COC concentration did not influence metal uptake when all the experiments were considered together. There was generally no major difference in the metal bioavailability between the two different sizes of colloids isolated from the coastal waters (1–10 kDa and 10 kDa-0.2 μm), whereas metals bound with the larger size colloids isolated from the estuarine waters were more bioavailable than metals bound with the smaller size colloids. The bioavailability of Cr and Fe bound with the colloids from estuarine waters was generally lower than those bound with colloids from the coastal waters. This study demonstrated that the geochemical properties of colloids (origin) and the chemical properties of metals are critical in affecting the bioavailability of colloid-bound metals to marine bivalves. Published online: 21 June 2002     

Enzymatic and cellular level effects of chromium∗

Exposure of Cr to four hepatic enzymes activities of tilapia, viz. acid‐ and alkaline phosphatases, catalase and glucose‐6‐phosphatase, was contrary to the results obtained for Cd and Ni. This is the only heavy metal investigated thus far that dramatically augmented glucose‐6‐phosphatase by approximately 83% at a concentration of 12 mg L^‐1 in vivo in lieu of the fact of an initial inhibition of approximately 45 % at a lower concentration of Cr; 6 mg L^‐1. In the case of acid phosphatase and catalase activities progressive increment was observed up to 50 and 217% respectively at a concentration of 12 mg L^‐1 Cr. On the other hand, in contrast to all the investigated enzymes interestingly alkaline phosphatase was inhibited continuously at all concentrations up to 46% at 12 mgL^‐1 Cr. In vitro experiments were contrary to the above mentioned results, whereby all hepatic enzymes were inhibited with major inhibition observed for acid phosphatase of approximately 60% from 5 mgL^‐1 Cr onwards in the system.

At cellular level, Cr exposure at a lethal dose of 12 mgL^‐1 demonstrated similar effects to that of Cd. In general, the glycogen and fat reserves were depleted while lysosomal activity is increased. As compared to the effects of Cd, the mitochondria did not indicate any prominent reflection in the formation of intramitochondrial bodies. Further, similar to Cd, the cell membrane as well as nucleus were not affected.     

Sperm morphology in the marine gastropodArchitectonica perspectiva (Mollusca): Unique features and systematic relevance

The marine amphipodAllorchestes compressa Dana, fed on the seagrassHeterozostera tasmanica, was exposed to sublethal concentrations of Cd, Cr, Cu and Zn for 4 wk in flowing sea water, and the concentrations producing the minimum detectable decreases (the minimum effect concentrations, MECs) in average weight, survival and biomass (average weight × survival proportion) were estimated by interpolation from regression models. Survival and biomass were more sensitive than average weight as indicators of sublethal effects. The lowest values of MEC for Cd, Cr, Cu and Zn were 11, >250, 3.7 and 99µg 1^–1, respectively. For Cu, this value fell below the minimum risk concentration (MRC) calculated from acute toxicity tests (LC₅₀) and application factors (AF); for Cd, the MEC was similar to the MRC; for Cr and Zn, the MECs were well above the MRCs. The metal concentrations in the amphipods at the MECs were 46, >46, 364 and 139µg g^–1 dry wt for Cd, Cr, Cu and Zn, respectively. Accumulation of the nutrient metals (Cr, Cu and Zn) showed some evidence of metabolic regulation, but the non-nutrient Cd was accumulated without regulation until the amphipods died. In general, those metals that were more highly accumulated by the amphipods were the more toxic.     

Cadmium uptake by a phytoplankton species in the presence of different inhibitors&

The uptake of cadmium by the Haptophyceae Hymenomonas elongata was studied as regards the energetic processes and Ca‐transport. For this purpose, experiments were carried out in the presence of an uncoupler of the phosphorylation : CCCP and of an inhibitor of calcium channels and also of Ca²⁺‐ATPase : verapamil. To reduce the number of assays, a factorial experimental design was used, in which all variables:— concentration of Cd in the medium—incubation time and—the presence of the inhibitor, are at two levels. In the absence of inhibitor, Cd uptake was found to vary as a function of metal concentration in the medium and of incubation time. CCCP significantly increased Cd uptake by H. elongata at sufficient incubation time. Therefore Cd uptake seemed linked to an energy‐dependent process, involving an ATPase. Verapamil immediately increased Cd uptake, implying an interaction between Cd and Ca.     

Effects of salinity on the uptake of lead and cadmium by two mangrove species Rhizophora apiculata Bl. and Avicennia alba Bl.

The uptake of lead (Pb) and cadmium (Cd) by Rhizophora apiculata and Avicennia alba under various salinity levels was examined using hydroponic cultivations. After 3 months of exposure at four levels of Pb (0, 0.03, 0.3 and 3 mg·L^?1) and four levels of Cd (0, 0.005; 0.05 and 0.5 mg·L^?1) at different salinities (0, 15 and 30), uptake of the metals was shown to be differently affected by salinity. For uptake of Pb by R. apiculata, the salinity effect was not significant for the leaves and was most significant in the stem, whereas for A. alba, the effect of salinity was significant only in the stem. Uptake of Pb in the roots and stems of both species was similar, but a higher concentration was recorded in the leaves of A. alba. Salinity was shown to affect the uptake of Cd by all tissues of R. apiculata, but most significantly roots. For A. alba, salinity significantly affects the total uptake of Cd, but this is most significant in the roots. The two mangrove species demonstrated different mechanisms of metal distribution into their organs which may be related to different adaptation mechanisms to saline conditions.     

Sorption du cadmium par une population de la diatomée Phaeodactylum tricornutum en culture

The uptake of cadmium by the marine diatom Phaeodactylum tricornutum (Bohlin) maintained in batch culture was measured as a function of successive growth stages of the diatom, and of the chemical form of cadmium in the culture medium (10 g Cd.l^-1). The relative importance of adsorption and absorption of cadmium by the diatom was evaluated. When cadmium was chelated by ethylenediaminetetraacetate (EDTA) the uptake was negligible. In the absence of a chelating agent the uptake varied with the growth phase of the culture, and the major part of the uptake was by adsorption. Two opposite phenomena seen to be responsible for the processes observed: adsorption of cadmium on the cell walls followed by a gradual elution (desorption) by external metabolites.     

Growth responses of the newly-discovered Cd-hyperaccumulator Rorippa globosa and its accumulation characteristics of Cd and As under joint stress of Cd and As

Rorippa globosa has been identified as a newly-found Cd-hyperaccumulating species. In the present study, growth responses of Rorippa globosa and its accumulation characteristics of Cd and As were examined under joint stress of Cd and As. The results showed that Cd and As had an antagonistic effect on enhancing the growth of Rorippa globosa plants and Cd uptake and accumulation under the low concentration Cd and As treatments. When the concentration of Cd in the soil was 10 mg/kg and the concentration of As was 50 mg/kg, the highest growing height of the plant was up to 35.9 cm and the dry weight of the shoots was up to 2.2 g/pot, respectively. Meanwhile, the accumulation of Cd in the leaves under the joint stress was higher than that at the same level under single Cd pollution. However, there were synergic adverse effects on plant growth and Cd uptake under the combined pollution from a high concentration of Cd and As. Meanwhile, the accumulation of As in the roots was greater than that in the shoots, the translocation factor (TF) was ?0.3 and the bioaccumulation factor (BF) was ?0.6, thus showing that Rorippa globosa had an excluding effect on As uptake. These results confirmed that Rorippa globosa had a strong tolerant ability to the joint stress of Cd and As, and the potential for phytoremediation of soils contaminated by Cd and As.     

Chromate bioavailability to the mollusc Venus Verrucosa

In this work the biokinetics of ⁵¹CrO² ₄ ^‐ in the edible mollusc Venus Verrucosa were studied. Laboratory uptake experiments, using two groups of Venus verrucosa, were performed, in aquaria containing sea water with Na₂ ⁵¹CrO² ₄ ^‐, in concentrations of 40 and 80 μCi/201 respectively. The distribution pattern of ⁵¹CrO² ₄ ^‐ in the body of V. verrucosa was studied. The biological half time of ⁵¹CrO² ₄ ^‐ was also found (Tb_1/2 = 41.8d). The concentration factors for ⁵¹CrO² ₄ ^‐ were found to be low (k～2) for both concentrations used. From the accumulated whole body radioactivity 59.0% was found in the shell. In the internal tissues viscera and gills display the greater ability to accumulate ⁵¹Cr in its hexavalent state.     

Body burden of chromium,copper, cadmium and lead in the neustonic copepod Anomalocera patersoni (pontellidae) collected from the Mediterranean sea

The amounts of Cr, Cu, Cd and Pb in the copepod Anomalocera patersoni were determined for 47 individuals by flameless atomic absorption spectrophotometry. The following mean body burdens of these elements were obtained: Cr 0.6, Cu 13, Cd 0.5, Pb 1.5 ng individual^-1, or Cr 2.1, Cu 42, Cd 1.5 and Pb 4.8 ng mg^-1 (dry weight). Cr, Cu and Cd contents did not differ significantly between males and females, however Pb did, with males having more. The data indicate that while the Cr, Cu and Pb body Hurden in these copepods follows the logarithmic normal distribution, Cd follows a normal distribution. Thus, the arithmetic means and the modes of Cd body burden are almost the same, while for the other elements the arithmetic means differ from the geometric means. This indicates that measurements of a few individuals suffice for estimating the mean body burden of Cd. On the other hand, many measurements are necessary for the body burden estimation of other elements, especially Cu.     

Production primaire pélagique de l'Etang de Berre en 1977 et 1978. Comparaison avec le milieu marin (Méditerranée nord-occidentale)

Measurements of primary production and photosynthetic efficiency were carried out in the brackish lake “Etang de Berre” near Marseilles (France), which is diluted by the Durance River, and in the area of Carry-le-Rouet (Mediterranean Sea) about 25 km off the Rhône River outlet. Primary production (¹⁴C) estimations were made in Etang de Berre from December 1977 to November 1978. The carbon uptake rates ranged between 38 and 1 091 mg C m^-3 d^-1, with an average surface value of 256 mg; water-column carbon-uptake rates ranged between 240 and 2 310 mg C m^-2 d^-1, with an average of 810, representing 290 g C m^-2 per year and 45 000 tons per year of photosynthetized carbon for the whole lake. Gross photosynthetic production measured by the method of Ryther was studied over a 2 yr period. The values obtained from marine water (Carry-le-Rouet) ranged from 23 to 2 337 mg C m^-2 d^-1, with a weighted average of 319, representing about 110 g C m^-2 per year. The values in brackish water (Etang de Berre) ranged from 14 to 1 778 mg C m^-2 d^-1, with a weighted average of 682, representing 250 g C m^-2 per year and 38 400 tons per year of photosynthesized carbon for the whole lake. The values derived from both methods of primary production measurements are approximately similar. Net production (computed from biomass estimations by Utermöhl's method) was compared with gross photosynthetic production. The net production in marine water did not display significant variations: most values were usually near zero. On the other hand, net production in brackish water exhibited a number of clear variations compared with concentrations of gross photosynthetic production during the whole 2 yr period. This large difference between estimations of gross and net production may be due to grazing, which is high in Etang de Berre, but slower and more constant in seawater. The ratios of primary production: chlorophyll a and gross photosynthetic production: biomass were also studied. In Etang de Berre, the former ratio ranges between 0.57 and 3.75, with an average of 1.44; this is similar to previously reported values. The ratio gross production: biomass in Etang de Berre varies between 0.3 and 4.2, with an average of 1.27, also confirming previous data. The very high values calculated for marine waters in the present study may result from an under-estimation of biomass.     

Biokinetic modeling of heavy metals in earthworms

Studies concerning bioaccumulation kinetics and bioconcentration factor (BCF) of heavy metals like zinc (Zn), lead (Pb), chromium (Cr), cadmium (Cd), and copper (Cu) in earthworm Eudrilus eugeniae tissues including integument, gizzard, clitellum, and head region were undertaken. Calculated BCF, predicted K _ow, and predicted K _oc showed a significant correlation between heavy metals in different earthworm tissues, in substrate spiked with heavy metals. The regression coefficient (r ²) between heavy metal uptake concentration and exposure time varied between 0.73 and 0.99, indicating significant correlation. The K _oc was a maximum of 13.9016 in case of Cu and integument at an exposure time of 100 days and a minimum of 0.1114 in case of Cr with respect to head at the same exposure time. Earthworms accumulated heavy metals following chronic exposure to municipal solid waste containing heavy metals. BCF and uptake rate kinetics of heavy metals were calculated and showed increased values in head tissue followed by integument.     

Calanoid copepod eggs in sea-bottom muds. IV. Effects of some environmental factors on the hatching of resting eggs

During cadmium uptake by the shore crab Carcinus maenas (L.), cadmium appears in both haemolymph and urine within 1 h, and comes into equilibrium with the haemolymp after some 60 h. The equilibrium concentration for haemolymph cadmium is always considerably less than that of the external medium, whether the latter is close to background level or at the artificially high concentration of 2.2 mg l^-1. Despite earlier evidence that cadmium entering the haemolymph is mainly bound to protein, current results show most of this to be freely labile and quickly displaced by cadmium taken up subsequently. There is some evidence to suggest that cadmium is passed on from the haemolymph to the hepatopancreas. A large proportion of whole-body cadmium is adsorbed onto the exoskeleton and gills. The comparatively rapid efflux of ¹⁰⁹Cd from loaded crabs over a period of 1 week is mainly due to desorption of this cadmium from the outer body surface.