Cd Uptake Rate Research Articles

Genetic line effects on parameters influencing cadmium concentration in lettuce(Lactuca sativaL.)

Abstract Cd uptake rates, translocation percentages, and shoot:root ratios were determined for 4 lettuce lines known to concentrate different levels of leaf Cd. Uptake rates were measured for one hr on 14‐day‐old plants exposed to Cd concentrations ranging from 2.5 to 100.00 nM. PI 278080, the high Cd line, had the highest uptake rate; PI 140398 and PI 169493, 2 low‐Cd lines, had intermediate uptake rates; and ‘Ruby’, a low‐to‐intermediate line, had the lowest overall uptake rate. Translocation percentages and shootrroot ratios were measured from one to 7 days on 15‐ to 21‐day‐old seedlings grown at 0.4 μM Cd. PI 278080 and ‘Ruby’ translocated about 40% of absorbed Cd to shoots, whereas PI 140398 and PI 169493 translocated about 30%. The shoot:root ratios of PI 278080, PI 140398 and PI 169493 ranged from 2.5 to 2.7, and these values were significantly lower than the ratio of 3.4 for ‘Ruby’.

Residence times for Cd and PO 4 in Funka Bay, Japan

The fluxes of Cd and PO 4 were measured during the summer using a sediment trap moored in Funka Bay. These fluxes were corrected with a phytoplankton decomposition rate constant obtained by a laboratory experiment because of decomposition of organic matter in the trap. The residence times for Cd and PO 4 in the bay were calculated by dividing their standing stocks in the water column by the corrected fluxes, on the assumption that Cd and PO 4 are at steady-state during the summer. The calculated residence times for Cd and PO 4 in the 0–40 m depth interval were 117 and 58 days in 1985, and 124 and 50 days in 1987, respectively. The residence time for Cd was approximately twice as long as that for PO 4. These values were in good accordance with the results previously obtained from the uptake rate constants of Cd and PO 4 in the bay. These results also indicate that the uptake rates of Cd and PO 4 by phytoplankton in the euphotic zone reflect the residence times for these elements.

The influence of pre-treatment, temperature and calcium ions on trace element uptake by an alga (Scenedesmus pannonicus subsp. Berlin) and fungus (Aureobasidium pullulans)

Experiments were carried out in order to obtain information on the uptake characteristics of metals in the algal and fungal components of lichens. The uptake of (115)Cd, (65)Zn, (64)Cu, (140)La, (187)W and (76)As in the alga Scenedesmus pannonicus, subsp. Berlin and the fungus Aureobasidium pullulans was determined at pH 7 and 5 respectively, in 4 h experiments varying with respect to temperature and Ca(2+) solution concentrations. Furthermore, the effects of pre-rinsing the cell suspensions on metal uptake were investigated.Pre-rinsing resulted in decreased uptake of W and As by algae and in increased uptake of all elements measured by fungi, which may be attributed to combined effects of starvation and changing densities.For algae, the uptake rates of As, W, Zn and Cd were markedly increased at the highest temperature employed. For Cu and La hardly any effects of temperature were observed, indicating the absence of metabolically controlled uptake. For fungi, but for As no relation of uptake with temperature could be determined.The presence of Ca(2+) ions in the solution applied hardly affected the uptake of As but resulted in increased uptake of W by both the algae and the fungi. The effects of Ca(2+) on the uptake of Cu and La were relatively small, probably due to specific binding sites in the cell walls for Cu and to the 'supercalcium' status of the La-ion.The presence of Ca(2+) caused decreased uptake of Cd(2+) and Zn(2+) by algae, but hardly affected the uptake of Zn(2+) by fungi.The results indicate component-specific uptake and accumulation behaviour in intact lichens.

A comparison of metal-binding proteins and cadmium metabolism in the marine molluscs Littorina littorea (gastropoda), Mytilus edulis and Macoma balthica (bivalvia)

Studies on the processes of Cd accumulation, turnover and storage in marine molluscs have revealed important qualitative and quantitative differences between species. In Littorina littorea collected from uncontaminated sites, Cd is predominantly bound to metallothionein (MT)-like proteins. Exposure to Cd, in the laboratory and field, results in an increase in Cd bound to these proteins, together with limited increases in Cd in the high molecular weight (HMW) pool (the latter partly a result of haemocyanin-mediated transport of Cd in the haemolymph). Polarographic determination of heat-stable MT-like compounds in L. littorea indicates there is little overall increase in the amount of protein produced in response to Cd exposure, suggesting that much of the newly incorporated metal may be bound to previously synthesised material. Relatively high levels of MT-like proteins, notably in the digestive gland (the major Cd-storage organ), appear to be an inherent feature of this species even in uncontaminated areas. MT-like proteins also sequester much of the Cd in exposed mussels Mytilus edulis, though, unlike Littorina, protein induction can be quantitatively related to exposure. In contrast, tellinid clams, Macoma balthica, fail to produce MT-like compounds, even in highly contaminated conditions, and Cd is mainly bound to HMW proteins. These variations in metal-binding behaviour probably explain the large interspecific differences in experimentally-determined Cd uptake rates and may account for differences in bioaccumulation potential observed in the field. Despite such variability, all three species studied appear to tolerate an influx of Cd provided the normal partitioning of metal is not irreversibly disturbed. Maintaining intracellular homeostasis, albeit at elevated Cd concentrations, probably compensates for the inability of these animals to regulate Cd uptake and for their extremely slow rates of Cd excretion.

Mechanism controlling Cd and PO 4 concentrations in Funka Bay, Japan

Seawater concentrations of dissolved Cd and PO 4 from the euphotic zone at Funka Bay were determined during March–August 1984. The bay is isolated from the outside sea during this period. The concentrations decrease with time from March to August. Plotting [Cd] vs. [PO 4] results in a convex curve about a straight line through the origin. In addition, the uptake rates for both Cd and PO 4 were measured by culture experiments involving several phytoplankton species. By assuming that the uptake rates are first-order, the following equation was obtained: [Cd] = exp( Kln [PO 4] + const.), where K represents the ratio of the rate constants for the uptake of Cd and PO 4. For K = 1, the points lie on a straight line through the origin, whereas for K < 1, a convex curve above the straight line is obtained. In the culture experiments the K values were all <1. The mechanism controlling the seasonal variations of [Cd] and [PO 4] in the bay can be explained by the uptake rates of Cd and PO 4.

Accumulation of cadmium in the mussel Mytilus edulis: kinetics and importance of uptake via food and sea water

In a short-term (162 h) accumulation experiment with mussels Mytilus edulis exposed to 100 ppb Cd and fed algal cells (Phaeodactylum tricornutum) in 1986, it was found that uptake via food played an insignificant role compared to direct uptake from ambient water (19‰ S). From measurements of the filtration rate and Cd uptake rate, it was estimated that the fraction of Cd taken up per liter of water filtered was about 0.15%. The initial uptake of Cd was linear with time and about three times higher in fed than in starved mussels. From the measured uptake of Cd in starved mussels collected in 1982 and exposed to 10, 100 and 200 ppb in long-term experiments (up to 242 d), it was found that the Cd Accumulation rate was not linear with time, and that the Cd uptake was not directly proportional with the exposure concentration. Values as high as 100 to 1 300 ppm Cd (dry wt of soft parts) were measured. It was found that the Cd elimination rate was not directly proportional with the Cd body burden in long-term exposed mussels, thus indicating that a certain fraction of Cd may have been immobilized to metallothioneins.

Uptake and toxic effects of heavy metal ions: interactions among cadmium, copper and zinc in cultured cells.

Absorption of metal ions by KB, HeLa and L-59 cells has been analyzed by atomic absorption spectrophotometry in the course of culture. Ions of the elements of the fourth period in the periodic chart such as Fe(II), Cu(II), Zn(II), Mn(II) and Ni(II) were not taken up, but those of the higher periods, such as Cd(II), Pb(II), Hg(II) and Ag(I) were were taken up easily. The uptake behavior by the cultured cells was in accordance with the characteristic features of metals, that metals in the fourth period are essential elements, and most of the elements of the fifth and the sixth periods are non-essential or toxic elements. The initial rate of Cd(II) uptake and the Cd(II) concentration has a sigmoidal relationship. Cd(II) was absorbed homotropically through cell membranes. The uptake of Cd(II) was specifically inhibited by Cu(II), but was affected little by Zn(II). The toxicity of Cd(II) to KB cells was greatly enhanced in the presence of Cu(II). On the contrary, the toxicity of Cd(II) was reduced by the addition of Zn(II) at several concentrations of Cd(II). The toxicity of Cd(II) did not depend on the amount of Cd(II) absorbed in the cells, but was determined by cofactors such as Cu(II). The interaction between Cd(II) and Cu(II) may be important for Itai-itai disease.

FACTORS AFFECTING THE KINETICS OF INTRA-AND EXTRACELLULAR CADMIUM UPTAKE BY THE MOSS RHYTIDIADELPHUS SQUARROSUS.

The responses of field-grown and cultured shoots of a moss, Rhytidiadelphus squarrosus (Hedw.) Warnst, to Cd were investigated. Respiration was not affected, but photosynthesis was progressively reduced with increasing Cd uptake. Field-grown shoots of two morphologically distinct populations differed in their photosynthetic responses to Cd. This could be related to different rates of Cd uptake by the two populations. During storage of Cd-treated shoots, movement of extracellular Cd to an intracellular location occurred, and this was reflected in altered photosynthetic rates. The maximum extracellular uptake capacity and affinity for Cd were identical for the two populations of field-grown shoots. Field-grown material from the two populations differed significantly in their intracellular Cd uptake characteristics, cation contents, gas exchange rates and dry weights per unit length. These differences were eliminated by laboratory culture. Cultured shoots had increased affinity for both intra- and extracellular cadmium uptake compared to field-grown shoots. The results indicate that the activity of Cd and other divalent cations at the plasmalemma may control the affinity for and accumulation of Cd by this moss. The results are discussed in terms of the design of experiments in studies of ion uptake and tolerance in bryophytes.

Cadmium uptake by rat red blood cells

Rat red blood cells were employed to study the uptake of cadmium ( 109Cd). Suspensions of red blood cells were exposed to Cd concentrations of 0.005–500 μM, which were representative of whole blood concentrations (both bound and free) observed following in vivo Cd administration. Cd uptake was biphasic with an initial rapid phase (< 1 min) followed by a slower second phase. The rate of Cd uptake at 25°C was one-fourth of that at 37°C. The metabolic inhibitors; sodium fluoride (1 mM), potassium cyanide (1 mM) and carbonyl cyanide- m-chlorophenyl hydrazone (2 μM) and the Na +K +ATPase inhibitor, ouabain (1 mM) did not reduce Cd (50 μM) uptake into red blood cells. This suggests that the uptake of Cd into red blood cells was not an active process. Incubation of Cd (10 μM) with an equimolar concentration of Zn did not alter uptake of Cd into red blood cells, but at 5 and 10 times higher concentrations of Zn, Cd uptake was enhanced 5-fold. Mercury at one-tenth and equimolar concentrations of Cd increased Cd uptake by red blood cells 2-fold. N-Ethylmaleimide (0.5–5 mM), which irreversibly inactivates membrane sulfhydryl groups, decreased Cd uptake. The data indicate that Cd uptake into rat red blood cells occurs by passive transport and that alterations of sulfhydryls of red blood cell membrane may modulate the process.

Uptake and excretion of cadmium, CdEDTA, and zinc by Macoma balthica.

The accumulation of cadmium from sea water by marine invertebrates has been studied. Chelation of Cd with ethylenediaminetetraacetic acid (EDTA) was reported to double the rate of Cd uptake and the final tissue concentration in mussels. The physicochemical properties of Cd and Zn are similar and it has been suggested that the two elements are biologically antagonistic. When both Cd and Zn are present, the level of Cd is reduced in polychaete worms and bivalve molluscs. In contrast, the level of Cd remained fairly constant for most tissues of P. montagui exposed to Cd at a constant level and to Zn at different levels. Because of the contrasting results concerning the effects of Cd and Zn combined, and of chelated Cd, this study was undertaken to determine if exposure to Cd and Zn in combination affects uptake and excretion of either element by the deposit-feeding mollusc, Macoma balthica. In addition, the effects of Cd complexed with EDTA and the chemical form of Cd on uptake of Cd in M. Balthica were examined.

THE RELATIONSHIP BETWEEN CADMIUM UPTAKE AND HEAVY METAL TOLERANCE IN THE LICHEN GENUSPELTIGERA

SummaryIntra‐ and extra‐cellular Cd uptake were investigated in members of the lichen genusPeltigerasampled from sites with contrasting metal status.Peltigera membranacea(Ach.) Nyl. from a disused Zn mine, previously shown to be tolerant to Zn‐induced inhibitions of photosynthesis, displayed a reduced rate of Cd uptake into the cell compared withPeltigeraspp. from unpolluted sites, suggesting metal exclusion was a tolerance mechanism. Although some differences in extracellular Cd uptake were found, these appeared to be a reflection of inter‐specific variation rather than environmentally‐induced alterations in Cd‐binding capacity. Exposure to a mixture of Cd and Mg showed that intracellular Cd uptake was less inhibited by Mg when lichens originated from the Zn mine, also implying that mine‐site plants had modified uptake systems. Although intracellular Cd uptake is normally light‐stimulated inPeltigera, lichens from the Zn mine lacked this response, suggesting that algal uptake was reduced more than fungal uptake. Photosynthetically Zn‐tolerantP. hymenina(Ach.) Delise from a disused Pb mine, more moderately polluted than the Zn mine, had intracellular Cd uptake rates comparable to those found in lichens from background localities. In addition, treatment of lichens for 1 week with low concentrations of Zn, previously shown to induce photosynthetic Zn and Cd tolerance, had no effect on intracellular Cd uptake. Tolerance in these instances must have been achieved by some other means. It is suggested that a severe metal stress may be required before metal tolerance by exclusion occurs.

Sequential Extraction of Soil Heavy Metals Following a Sludge Application

AbstractTwo soils treated with a composted sludge and two liquid sludges annually for 7 consecutive years and cropped to barley (Hordeum vulgare L.) each year were sampled at 4‐week intervals following planting in 1981. The soils were Greenfield sandy loam (coarse‐loamy, mixed, thermic, Typic Haloxeralf) and Domino loam (fine‐loamy, mixed, thermic, Xerollic Calciothid). Barley tissue samples were also obtained at the time of each soil sampling. Soils were fractionated with a sequential extraction procedure to determine the distribution of solid‐phase chemical forms of the sludge‐borne heavy metals. In untreated soils, essentially all of the heavy metals were present in either the sulfide‐residue form (for Cr, Cu, Ni, and Zn) or the carbonate form (for Cd and Pb). With sludge treatment, every extracted fraction showed increases in the amounts of heavy metals. However, the most significant increases occurred in the carbonate fraction and, sometimes, in organically bonded fractions as well. There was little indication that the distribution pattern of the solid‐phase heavy metals in the sludge‐treated soils changed with time from planting to harvesting. The Cd and Zn concentrations in barley grown in the sludge‐treated soil were consistently higher than those in the nonsludged control. The rate of Cd and Zn uptake was rapid during early stages of plant growth. However, the rate of Cd and Zn uptake by barley progressively decreased with plant development. As a result, the part of the plant that developed at the later stages of plant growth (e.g., the barley grain) always contained less Cd and Zn than those that developed earlier. Since the percentage of Cd and Zn in each extracted fraction did not change appreciably throughout the growing season, the differential Cd and Zn uptake by barley with plant development cannot be related to the chemical transformation of solid‐phase heavy metals in the soil during the growing season.

The Control of Cadmium Uptake in the Lichen Genus Peltigera

Intra- and extracellular Cd uptake in the lichen genus Peltigera were investigated, and intracellular uptake found to display Michaelis-Menten kinetics. Compared with values reported for Zn uptake in free-living algae and fungi, Peltigera had low affinities for Cd and low maximum uptake rates. Intra-, and to a lesser extent extracellular uptake rates were temperature dependent. When lichens were incubated concurrently with Cd and equimolar concentrations of a range of other cations, most were found to reduce both extra- and intracellular Cd uptake, implying that the Cd uptake systems had low specificities. Mg, though not a strong competitor for extracellular Cd uptake, inhibited intracellular Cd uptake to a similar extent to borderline elements, and it is postulated that intracellular Cd uptake occurs by a system which normally transports Mg. Although concurrently-supplied cations reduced Cd-induced inhibitions of photosynthesis, the reductions were not proportional to the effect of the cations on intracellular Cd uptake. This indicated that other cations affected the toxicity of Cd to photosynthesis by some means in addition to reducing Cd uptake. Intracellular Cd uptake was light-stimulated, suggesting that a close relationship existed between metal uptake and metabolism. The rate of intracellular Cd uptake in the dark was probably not directly linked to the supply of respirable reserves, as it was unaffected by prolonged storage in the dark, and was not increased by adding glucose. It is hypothesized that light-stimulated Cd uptake represents active entry into algal cells, but with uptake in the dark it is not clear which symbiont is involved, and whether energy is required.

Physiological responses of estuarine animals to cadmium pollution

Toxic effects of cadmium contamination may be observed at all levels of organismic organization. In estuarine areas the sensitivity of euryhaline species to acute Cd toxicity is strongly modified by various abiotic factors, whereas long-term threshold values are less dependent on environmental parameters. Experiments with larval stages of the molluscMytilus edulis reveal that Cd effects on life functions such as development and growth are differentially modified by temperature and salinity. High Cd concentrations can be accumulated by adult bivalves of coastal areas without signs of physiological damage. Mechanisms of heavy-metal detoxication in these molluscs seem to be quite different from those known to exist in vertebrates. Among decapod crustaceans, stenoecous species tend to exhibit higher rates of Cd uptake than euryoecous ones. Rates of Cd uptake and of accumulation depend on external and internal factors. In adultNereis succinea individuals sublethal Cd effects have been recorded on growth and food conversion (in terms of energy content).

Effects of chronic cadmium exposure on crayfish survival, growth, and tolerance to elevated temperatures.

Crayfish Cambarus latimanus were subjected over a 5-month period to 0.02, 5, and 10 microgram Cd/L in a continuous flow system at ambient winter temperatures. Uptake of cadmium, growth, and mortality were measured. One-half of the surviving crayfish were analyzed for Cd after completion of the 5-month experiment, while the remaining half were removed from the contaminated water and subjected in a static laboratory experiment to stepwise, daily increases in temperature. The results indicated that (1) the rate of Cd uptake in crayfish was positively related to external concentration, (2) mortality increased significantly with higher Cd concentrations, and (3) neither growth nor thermal tolerance was significantly related to the Cd concentration in the crayfish tissues. The importance of chronic, low-level studies is discussed.

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 μg/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.

Toxicity of Cadmium in the Freshwater Snail, Physa gyrina Say

AbstractUsing both mature and immature snails and cadmium as the toxicant, 50% tolerance limits (TL50) for various exposure durations were determined graphically. The immature snails 96‐hour TL50 of 0.43 ppm indicates they are three times as sensitive to Cd as mature snails whose 96‐hour TL50 was 1.37 ppm. Survivors of bioassays and their offspring were observed. The rate of Cd uptake by snails exposed to 1.30 ppm Cd solution over a 24‐hour period was 0.550 ppm/hour. Following the 24‐hour exposure, the rate of elimination during the next 24 hours was 0.229 ppm/hour. The rate of uptake was nearly twice the rate of elimination, allowing accumulation of Cd in the snail. The higher the Cd concentration to which snails were exposed, the fewer the survivors, the lower their reproductive potential, and the shorter the period the young survived.

The influence of hardness components (Ca 2+ and Mg 2+) in water on the uptake and concentration of cadmium in a simulated freshwater ecosystem

To determine whether hardness components in water influenced uptake and concentration of Cd in members of a simulated freshwater ecosystem, an alga ( Nitella flexilis), a rooted plant ( Elodea canadensis), infusoria snails ( Ampullaria paludosa), catfish ( Corydoras punctatus), and guppies ( Lebistes reticulatus) were cultured together for 1, 6, and 12 hr; and 1, 2, 3, 7, 11, 14 and 21 days in hard (total Ca 2+ and Mg 2+ approximately 150 ppm) or soft (total Ca 2+ and Mg 2+ 0 ppm) water containing an initial concentration of 0.1 ppm Cd-115. At the end of each of the 10 different exposure periods, specimens of each species were rinsed in distilled water, digested in nitric acid, plated on 2-in. stainless steel planchettes and dried. The amount of radioactivity indicated that the initial rate of Cd uptake by these organisms was faster in hard water than in soft water; however, the total concentration of Cd was greater in those organisms cultured in soft water than those in hard water.